// Copyright 2024 RustFS Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#![allow(dead_code)]

//! Statistics collection functions for metrics.
//!
//! This module contains functions that collect statistics from various
//! RustFS internal sources (storage layer, bucket monitor, system info)
//! and convert them to the Stats structs used by collectors.

use crate::metrics::collectors::{
    BucketReplicationBandwidthStats, BucketReplicationStats, BucketReplicationTargetStats, BucketStats, BucketUsageStats,
    ClusterConfigStats, ClusterHealthStats, ClusterStats, ClusterUsageStats, CompressionClusterStats, CpuStats, DiskStats,
    DriveCountStats, DriveDetailedStats, ErasureSetStats, HostNetworkStats, IamStats, IlmStats, MemoryStats, NetworkStats,
    ProcessStats, ProcessStatusType, ReplicationStats, ResourceStats, ScannerStats,
};
use crate::metrics::runtime_sources::{ObsIlmRuntimeSnapshot, bucket_monitor_handle, iam_metrics_snapshot, ilm_runtime_snapshot};
use crate::metrics::{
    BucketOperations, BucketOptions, ObsEcstoreResult, ObsStore, StorageAdminApi, obs_bucket_replication_stats_snapshot,
    obs_get_quota_config, obs_get_total_usable_capacity, obs_get_total_usable_capacity_free,
    obs_load_compression_total_from_memory, obs_load_data_usage_from_backend, obs_replication_site_stats_snapshot,
    obs_resolve_object_store_handle,
};
use chrono::Utc;
use rustfs_common::heal_channel::HealScanMode;
use rustfs_common::metrics::{ScannerMetricsReport, global_metrics};
use rustfs_io_metrics::internode_metrics::global_internode_metrics;
use rustfs_io_metrics::{
    ProcessResourceSnapshot, ProcessSampler, ProcessStatusSnapshot, ProcessSystemSnapshot, snapshot_process_resource_and_system,
    snapshot_process_resource_and_system_with,
};
use std::{collections::HashMap, sync::Arc, time::SystemTime};
use sysinfo::{Networks, System};
use tracing::{instrument, warn};

const LOG_COMPONENT_OBS: &str = "obs";
const LOG_SUBSYSTEM_METRICS_COLLECTOR: &str = "metrics_collector";
const EVENT_METRICS_COLLECTOR_STATE: &str = "metrics_collector_state";

type ObsStorageInfo = <ObsStore as StorageAdminApi>::StorageInfo;
type ObsBackendInfo = <ObsStore as StorageAdminApi>::BackendInfo;

struct ObsDataUsageInfo {
    last_update: Option<SystemTime>,
    buckets_count: u64,
    objects_total_count: u64,
    versions_total_count: u64,
    delete_markers_total_count: u64,
    objects_total_size: u64,
    buckets_usage: HashMap<String, ObsBucketUsageInfo>,
}

struct ObsBucketUsageInfo {
    size: u64,
    objects_count: u64,
    object_size_histogram: HashMap<String, u64>,
    object_versions_histogram: HashMap<String, u64>,
    versions_count: u64,
    delete_markers_count: u64,
}

#[derive(Debug, Clone, PartialEq)]
struct ObsBucketReplicationBandwidthStats {
    bucket: String,
    target_arn: String,
    limit_bytes_per_sec: i64,
    current_bandwidth_bytes_per_sec: f64,
}

fn usize_to_u64_saturating(value: usize) -> u64 {
    u64::try_from(value).unwrap_or(u64::MAX)
}

async fn load_obs_data_usage_from_backend(store: Arc<ObsStore>) -> ObsEcstoreResult<ObsDataUsageInfo> {
    let data_usage = obs_load_data_usage_from_backend(store).await?;

    Ok(ObsDataUsageInfo {
        last_update: data_usage.last_update,
        buckets_count: data_usage.buckets_count,
        objects_total_count: data_usage.objects_total_count,
        versions_total_count: data_usage.versions_total_count,
        delete_markers_total_count: data_usage.delete_markers_total_count,
        objects_total_size: data_usage.objects_total_size,
        buckets_usage: data_usage
            .buckets_usage
            .into_iter()
            .map(|(bucket, usage)| {
                (
                    bucket,
                    ObsBucketUsageInfo {
                        size: usage.size,
                        objects_count: usage.objects_count,
                        object_size_histogram: usage.object_size_histogram,
                        object_versions_histogram: usage.object_versions_histogram,
                        versions_count: usage.versions_count,
                        delete_markers_count: usage.delete_markers_count,
                    },
                )
            })
            .collect(),
    })
}

fn resolve_obs_object_store_handle() -> Option<Arc<ObsStore>> {
    obs_resolve_object_store_handle()
}

fn scanner_lifecycle_checked_versions(metrics: &ScannerMetricsReport) -> u64 {
    metrics
        .source_work
        .iter()
        .find(|source| source.source == "lifecycle")
        .map(|source| source.checked)
        .unwrap_or_default()
}

fn obs_total_usable_capacity_bytes(storage_info: &ObsStorageInfo) -> u64 {
    usize_to_u64_saturating(obs_get_total_usable_capacity(&storage_info.disks, storage_info))
}

fn obs_total_usable_capacity_free_bytes(storage_info: &ObsStorageInfo) -> u64 {
    usize_to_u64_saturating(obs_get_total_usable_capacity_free(&storage_info.disks, storage_info))
}

fn usable_capacity_used_bytes(usable_capacity: u64, free_bytes: u64) -> u64 {
    usable_capacity.saturating_sub(free_bytes)
}

async fn obs_bucket_quota_limit_bytes(bucket: &str) -> u64 {
    obs_get_quota_config(bucket)
        .await
        .ok()
        .and_then(|(quota, _)| quota.get_quota_limit())
        .unwrap_or(0)
}

fn obs_bucket_replication_bandwidth_stats() -> Option<Vec<ObsBucketReplicationBandwidthStats>> {
    let monitor = bucket_monitor_handle()?;
    Some(
        monitor
            .get_report(|_| true)
            .bucket_stats
            .into_iter()
            .map(|(opts, details)| ObsBucketReplicationBandwidthStats {
                bucket: opts.name,
                target_arn: opts.replication_arn,
                limit_bytes_per_sec: details.limit_bytes_per_sec,
                current_bandwidth_bytes_per_sec: details.current_bandwidth_bytes_per_sec,
            })
            .collect(),
    )
}

async fn obs_ilm_runtime_snapshot() -> ObsIlmRuntimeSnapshot {
    ilm_runtime_snapshot().await
}

async fn obs_bucket_replication_detail_stats() -> Vec<BucketReplicationStats> {
    obs_bucket_replication_stats_snapshot()
        .await
        .into_iter()
        .map(|stats| BucketReplicationStats {
            bucket: stats.bucket,
            total_failed_bytes: stats.total_failed_bytes,
            total_failed_count: stats.total_failed_count,
            last_min_failed_bytes: stats.last_min_failed_bytes,
            last_min_failed_count: stats.last_min_failed_count,
            last_hour_failed_bytes: stats.last_hour_failed_bytes,
            last_hour_failed_count: stats.last_hour_failed_count,
            sent_bytes: stats.sent_bytes,
            sent_count: stats.sent_count,
            proxied_get_requests_total: stats.proxied_get_requests_total,
            proxied_get_requests_failures: stats.proxied_get_requests_failures,
            proxied_head_requests_total: stats.proxied_head_requests_total,
            proxied_head_requests_failures: stats.proxied_head_requests_failures,
            proxied_put_requests_total: stats.proxied_put_requests_total,
            proxied_put_requests_failures: stats.proxied_put_requests_failures,
            proxied_put_tagging_requests_total: stats.proxied_put_tagging_requests_total,
            proxied_put_tagging_requests_failures: stats.proxied_put_tagging_requests_failures,
            proxied_get_tagging_requests_total: stats.proxied_get_tagging_requests_total,
            proxied_get_tagging_requests_failures: stats.proxied_get_tagging_requests_failures,
            proxied_delete_tagging_requests_total: stats.proxied_delete_tagging_requests_total,
            proxied_delete_tagging_requests_failures: stats.proxied_delete_tagging_requests_failures,
            resync_started_count: stats.resync_started_count,
            resync_completed_count: stats.resync_completed_count,
            resync_failed_count: stats.resync_failed_count,
            resync_canceled_count: stats.resync_canceled_count,
            resync_duration_ms: stats.resync_duration_ms,
            targets: stats
                .targets
                .into_iter()
                .map(|target| BucketReplicationTargetStats {
                    target_arn: target.target_arn,
                    bandwidth_limit_bytes_per_sec: target.bandwidth_limit_bytes_per_sec,
                    current_bandwidth_bytes_per_sec: target.current_bandwidth_bytes_per_sec,
                    latency_ms: target.latency_ms,
                })
                .collect(),
        })
        .collect()
}

async fn obs_site_replication_stats() -> ReplicationStats {
    let current_data_transfer_rate = obs_bucket_replication_bandwidth_stats()
        .into_iter()
        .flatten()
        .map(|stat| stat.current_bandwidth_bytes_per_sec)
        .sum::<f64>();
    let stats = obs_replication_site_stats_snapshot(current_data_transfer_rate).await;

    ReplicationStats {
        average_active_workers: stats.average_active_workers,
        average_queued_bytes: stats.average_queued_bytes,
        average_queued_count: stats.average_queued_count,
        average_data_transfer_rate: stats.average_data_transfer_rate,
        active_workers: stats.active_workers,
        current_data_transfer_rate: stats.current_data_transfer_rate,
        last_minute_queued_bytes: stats.last_minute_queued_bytes,
        last_minute_queued_count: stats.last_minute_queued_count,
        max_active_workers: stats.max_active_workers,
        max_queued_bytes: stats.max_queued_bytes,
        max_queued_count: stats.max_queued_count,
        max_data_transfer_rate: stats.max_data_transfer_rate,
        recent_backlog_count: stats.recent_backlog_count,
    }
}

fn current_scanner_cycle_age_seconds(
    current_cycle: u64,
    current_started: chrono::DateTime<Utc>,
    now: chrono::DateTime<Utc>,
) -> u64 {
    if current_cycle == 0 {
        0
    } else {
        now.signed_duration_since(current_started).num_seconds().max(0) as u64
    }
}

fn scanner_scan_mode_code(scan_mode: &str) -> u64 {
    match scan_mode {
        mode if mode == HealScanMode::Normal.as_str() => HealScanMode::Normal as u8 as u64,
        mode if mode == HealScanMode::Deep.as_str() => HealScanMode::Deep as u8 as u64,
        _ => HealScanMode::Unknown as u8 as u64,
    }
}

fn scanner_work_rate_per_second(count: u64, seconds: f64) -> f64 {
    if seconds > 0.0 && seconds.is_finite() {
        count as f64 / seconds
    } else {
        0.0
    }
}

const DRIVE_STATE_OK: &str = "ok";
const DRIVE_STATE_ONLINE: &str = "online";
const DRIVE_STATE_UNFORMATTED: &str = "unformatted";
const DRIVE_RUNTIME_STATE_RETURNING: &str = "returning";
const CAPACITY_OBSERVATION_LIVE: &str = "live";
const CAPACITY_OBSERVATION_STALE: &str = "stale";
const CAPACITY_OBSERVATION_MISSING: &str = "missing";

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct ErasureSetQuorumShape {
    data_shards: u32,
    read_quorum: u32,
    write_quorum: u32,
    read_tolerance: u32,
    write_tolerance: u32,
}

fn disk_is_online_for_metrics(state: &str, runtime_state: Option<&str>) -> bool {
    let state_is_acceptable = state.eq_ignore_ascii_case(DRIVE_STATE_OK)
        || state.eq_ignore_ascii_case(DRIVE_STATE_ONLINE)
        || state.eq_ignore_ascii_case(DRIVE_STATE_UNFORMATTED);

    if let Some(runtime_state) = runtime_state {
        let runtime_state_is_acceptable = runtime_state.eq_ignore_ascii_case(DRIVE_STATE_ONLINE)
            || runtime_state.eq_ignore_ascii_case(DRIVE_RUNTIME_STATE_RETURNING);
        return runtime_state_is_acceptable && state_is_acceptable;
    }

    state_is_acceptable
}

fn disk_capacity_observation_state(source: Option<&str>, age_seconds: Option<u64>) -> (&'static str, u64) {
    let age_seconds = age_seconds.unwrap_or(0);
    match source {
        Some("live_probe") => (CAPACITY_OBSERVATION_LIVE, age_seconds),
        Some("snapshot") => (CAPACITY_OBSERVATION_STALE, age_seconds),
        _ => (CAPACITY_OBSERVATION_MISSING, age_seconds),
    }
}

fn derive_erasure_set_quorum_shape(set_drive_count: usize, parity: usize) -> ErasureSetQuorumShape {
    let data_shards = set_drive_count.saturating_sub(parity);
    let read_quorum = data_shards.max(1);
    let mut write_quorum = read_quorum;
    if data_shards == parity {
        write_quorum += 1;
    }

    ErasureSetQuorumShape {
        data_shards: data_shards as u32,
        read_quorum: read_quorum as u32,
        write_quorum: write_quorum as u32,
        read_tolerance: parity as u32,
        write_tolerance: set_drive_count.saturating_sub(write_quorum) as u32,
    }
}

fn apply_erasure_set_health(entry: &mut ErasureSetStats) {
    let online = entry.online_drives_count;
    entry.read_health = u8::from(online >= entry.read_quorum);
    entry.write_health = u8::from(online >= entry.write_quorum);
    entry.health = u8::from(entry.write_health == 1);
}

#[derive(Debug, Clone, Default)]
pub struct ProcessMetricBundle {
    pub resource: ResourceStats,
    pub process: ProcessStats,
    pub disk_read_bytes: u64,
    pub disk_write_bytes: u64,
}

/// Collect cluster and cluster-health statistics from a single storage snapshot.
pub async fn collect_cluster_and_health_stats() -> (ClusterStats, ClusterHealthStats) {
    let Some(store) = resolve_obs_object_store_handle() else {
        return (ClusterStats::default(), ClusterHealthStats::default());
    };

    let storage_info = StorageAdminApi::storage_info(store.as_ref()).await;
    let raw_capacity: u64 = storage_info.disks.iter().map(|d| d.total_space).sum();
    let usable_capacity = obs_total_usable_capacity_bytes(&storage_info);
    let free = obs_total_usable_capacity_free_bytes(&storage_info);
    let used = usable_capacity_used_bytes(usable_capacity, free);
    let stale_capacity_drives = storage_info
        .disks
        .iter()
        .filter(|disk| {
            disk_capacity_observation_state(disk.capacity_observation_source.as_deref(), disk.capacity_observation_age_seconds).0
                == CAPACITY_OBSERVATION_STALE
        })
        .count() as u64;
    let missing_capacity_drives = storage_info
        .disks
        .iter()
        .filter(|disk| {
            disk_capacity_observation_state(disk.capacity_observation_source.as_deref(), disk.capacity_observation_age_seconds).0
                == CAPACITY_OBSERVATION_MISSING
        })
        .count() as u64;

    // Get bucket and object counts from data usage info.
    let (buckets_count, objects_count) = match load_obs_data_usage_from_backend(store.clone()).await {
        Ok(data_usage) => (data_usage.buckets_count, data_usage.objects_total_count),
        Err(e) => {
            warn!(event = EVENT_METRICS_COLLECTOR_STATE, component = LOG_COMPONENT_OBS, subsystem = LOG_SUBSYSTEM_METRICS_COLLECTOR, collector = "cluster_stats", result = "data_usage_load_failed", error = %e, "metrics collector state changed");
            // Fall back to bucket list for buckets_count, objects_count stays 0.
            let buckets = store
                .list_bucket(&BucketOptions {
                    cached: true,
                    ..Default::default()
                })
                .await
                .unwrap_or_else(|err| {
                    warn!(event = EVENT_METRICS_COLLECTOR_STATE, component = LOG_COMPONENT_OBS, subsystem = LOG_SUBSYSTEM_METRICS_COLLECTOR, collector = "cluster_stats", result = "bucket_list_failed", error = %err, "metrics collector state changed");
                    Vec::new()
                });
            (buckets.len() as u64, 0)
        }
    };

    let mut online = 0u64;
    let mut offline = 0u64;
    for disk in &storage_info.disks {
        if disk_is_online_for_metrics(disk.state.as_str(), disk.runtime_state.as_deref()) {
            online += 1;
        } else {
            offline += 1;
        }
    }

    (
        ClusterStats {
            raw_capacity_bytes: raw_capacity,
            usable_capacity_bytes: usable_capacity,
            used_bytes: used,
            free_bytes: free,
            stale_capacity_drives,
            missing_capacity_drives,
            objects_count,
            buckets_count,
        },
        ClusterHealthStats {
            drives_offline_count: offline,
            drives_online_count: online,
            drives_count: storage_info.disks.len() as u64,
        },
    )
}

/// Collect cluster statistics from the storage layer.
#[instrument]
pub async fn collect_cluster_stats() -> ClusterStats {
    let (cluster_stats, _) = collect_cluster_and_health_stats().await;
    cluster_stats
}

/// Collect cluster health statistics from the storage layer.
pub async fn collect_cluster_health_stats() -> ClusterHealthStats {
    let (_, cluster_health_stats) = collect_cluster_and_health_stats().await;
    cluster_health_stats
}

/// Collect bucket statistics from the storage layer.
pub async fn collect_bucket_stats() -> Vec<BucketStats> {
    let Some(store) = resolve_obs_object_store_handle() else {
        return Vec::new();
    };

    // Load data usage info from backend to get bucket sizes and object counts
    let data_usage = match load_obs_data_usage_from_backend(store.clone()).await {
        Ok(info) => Some(info),
        Err(e) => {
            warn!(event = EVENT_METRICS_COLLECTOR_STATE, component = LOG_COMPONENT_OBS, subsystem = LOG_SUBSYSTEM_METRICS_COLLECTOR, collector = "bucket_stats", result = "data_usage_load_failed", error = %e, "metrics collector state changed");
            None
        }
    };

    // List all buckets
    let buckets = match store
        .list_bucket(&BucketOptions {
            cached: true,
            ..Default::default()
        })
        .await
    {
        Ok(buckets) => buckets,
        Err(e) => {
            warn!(event = EVENT_METRICS_COLLECTOR_STATE, component = LOG_COMPONENT_OBS, subsystem = LOG_SUBSYSTEM_METRICS_COLLECTOR, collector = "bucket_stats", result = "bucket_list_failed", error = %e, "metrics collector state changed");
            return Vec::new();
        }
    };

    let mut stats = Vec::with_capacity(buckets.len());

    for bucket in buckets {
        if bucket.name.starts_with('.') {
            continue;
        }

        // Get size and objects_count from data usage info
        let (size_bytes, objects_count) = data_usage
            .as_ref()
            .and_then(|du| du.buckets_usage.get(&bucket.name))
            .map(|bui| (bui.size, bui.objects_count))
            .unwrap_or((0, 0));

        // Get quota from bucket metadata
        let quota_bytes = obs_bucket_quota_limit_bytes(&bucket.name).await;

        stats.push(BucketStats {
            name: bucket.name,
            size_bytes,
            objects_count,
            quota_bytes,
        });
    }

    stats
}

/// Collect bucket replication bandwidth stats from the global monitor.
pub fn collect_bucket_replication_bandwidth_stats() -> Vec<BucketReplicationBandwidthStats> {
    let Some(bandwidth_stats) = obs_bucket_replication_bandwidth_stats() else {
        return Vec::new();
    };

    bandwidth_stats
        .into_iter()
        .map(|stat| {
            let target_arn = stat.target_arn;
            let limit_bytes_per_sec = u64::try_from(stat.limit_bytes_per_sec).unwrap_or_else(|_| {
                warn!(event = EVENT_METRICS_COLLECTOR_STATE, component = LOG_COMPONENT_OBS, subsystem = LOG_SUBSYSTEM_METRICS_COLLECTOR, collector = "bucket_replication_bandwidth", result = "invalid_limit_value", target_arn = ?target_arn, limit_value = stat.limit_bytes_per_sec, "metrics collector state changed");
                0
            });

            BucketReplicationBandwidthStats {
                bucket: stat.bucket,
                target_arn,
                limit_bytes_per_sec,
                current_bandwidth_bytes_per_sec: stat.current_bandwidth_bytes_per_sec,
            }
        })
        .collect()
}

/// Collect bucket and target level replication stats from the global replication runtime.
pub async fn collect_bucket_replication_detail_stats() -> Vec<BucketReplicationStats> {
    obs_bucket_replication_detail_stats().await
}

/// Collect site-level replication stats from the global replication runtime.
pub async fn collect_replication_stats() -> ReplicationStats {
    obs_site_replication_stats().await
}

/// Collect disk statistics from the storage layer.
pub async fn collect_disk_stats() -> Vec<DiskStats> {
    let (disk_stats, _, _) = collect_disk_and_system_drive_stats().await;
    disk_stats
}

fn build_system_cpu_stats(system: &System) -> CpuStats {
    let cpu_usage = system.global_cpu_usage() as f64;
    let cpu_count = system.cpus().len().max(1) as f64;
    let load_avg = System::load_average().one;

    CpuStats {
        avg_idle: (100.0 - cpu_usage).max(0.0),
        load_avg,
        load_avg_perc: (load_avg / cpu_count) * 100.0,
        usage_perc: cpu_usage,
    }
}

fn build_system_memory_stats(system: &System) -> MemoryStats {
    let total = system.total_memory();
    let used = system.used_memory();

    MemoryStats {
        total,
        used,
        used_perc: if total > 0 {
            (used as f64 / total as f64) * 100.0
        } else {
            0.0
        },
        free: system.free_memory(),
        buffers: 0,
        cache: 0,
        shared: 0,
        available: system.available_memory(),
    }
}

/// Collect system CPU and memory statistics from a shared sysinfo snapshot.
pub fn collect_system_cpu_and_memory_stats() -> (CpuStats, MemoryStats) {
    let mut system = System::new_all();
    collect_system_cpu_and_memory_stats_with(&mut system)
}

/// Collect system CPU and memory statistics by refreshing a reusable sysinfo instance.
pub fn collect_system_cpu_and_memory_stats_with(system: &mut System) -> (CpuStats, MemoryStats) {
    system.refresh_cpu_all();
    system.refresh_memory();
    (build_system_cpu_stats(system), build_system_memory_stats(system))
}

/// Collect system CPU statistics from the current host.
pub fn collect_system_cpu_stats() -> CpuStats {
    let (cpu_stats, _) = collect_system_cpu_and_memory_stats();
    cpu_stats
}

/// Collect system memory statistics from the current host.
pub fn collect_system_memory_stats() -> MemoryStats {
    let (_, memory_stats) = collect_system_cpu_and_memory_stats();
    memory_stats
}

/// Collect node disk stats and drive stats from a single storage snapshot.
pub async fn collect_disk_and_system_drive_stats() -> (Vec<DiskStats>, Vec<DriveDetailedStats>, DriveCountStats) {
    let Some(store) = resolve_obs_object_store_handle() else {
        return (Vec::new(), Vec::new(), DriveCountStats::default());
    };

    let storage_info = StorageAdminApi::storage_info(store.as_ref()).await;
    let disk_stats = storage_info
        .disks
        .iter()
        .map(|disk| DiskStats {
            server: disk.endpoint.clone(),
            drive: disk.drive_path.clone(),
            total_bytes: disk.total_space,
            used_bytes: disk.used_space,
            free_bytes: disk.available_space,
        })
        .collect();

    let mut online_count = 0u64;
    let mut offline_count = 0u64;
    let drive_stats = storage_info
        .disks
        .iter()
        .map(|disk| {
            let is_online = disk_is_online_for_metrics(disk.state.as_str(), disk.runtime_state.as_deref());
            let (capacity_observation_state, capacity_observation_age_seconds) = disk_capacity_observation_state(
                disk.capacity_observation_source.as_deref(),
                disk.capacity_observation_age_seconds,
            );
            if is_online {
                online_count += 1;
            } else {
                offline_count += 1;
            }

            DriveDetailedStats {
                server: disk.endpoint.clone(),
                drive: disk.drive_path.clone(),
                total_bytes: disk.total_space,
                used_bytes: disk.used_space,
                free_bytes: disk.available_space,
                capacity_observation_state,
                capacity_observation_age_seconds,
                used_inodes: None,
                free_inodes: None,
                total_inodes: None,
                timeout_errors_total: None,
                io_errors_total: None,
                availability_errors_total: None,
                waiting_io: None,
                api_latency_micros: None,
                health: if is_online { 1 } else { 0 },
                reads_per_sec: None,
                reads_kb_per_sec: None,
                reads_await: None,
                writes_per_sec: None,
                writes_kb_per_sec: None,
                writes_await: None,
                perc_util: None,
            }
        })
        .collect();

    let drive_count_stats = DriveCountStats {
        offline_count,
        online_count,
        total_count: online_count + offline_count,
    };
    (disk_stats, drive_stats, drive_count_stats)
}

/// Collect system drive statistics using the storage layer snapshot.
pub async fn collect_system_drive_stats() -> (Vec<DriveDetailedStats>, DriveCountStats) {
    let (_, drive_stats, drive_count_stats) = collect_disk_and_system_drive_stats().await;
    (drive_stats, drive_count_stats)
}

/// Collect resource and process statistics for the current process in one sysinfo refresh.
#[inline]
pub fn collect_process_metric_bundle() -> ProcessMetricBundle {
    let (resource_snapshot, process_snapshot) = snapshot_process_resource_and_system();
    process_metric_bundle_from_snapshots(resource_snapshot, process_snapshot)
}

#[inline]
pub fn collect_process_metric_bundle_with(sampler: &mut ProcessSampler) -> ProcessMetricBundle {
    let (resource_snapshot, process_snapshot) = snapshot_process_resource_and_system_with(sampler);
    process_metric_bundle_from_snapshots(resource_snapshot, process_snapshot)
}

fn process_metric_bundle_from_snapshots(
    resource_snapshot: ProcessResourceSnapshot,
    process_snapshot: ProcessSystemSnapshot,
) -> ProcessMetricBundle {
    let status = match process_snapshot.status {
        ProcessStatusSnapshot::Running => ProcessStatusType::Running,
        ProcessStatusSnapshot::Sleeping => ProcessStatusType::Sleeping,
        ProcessStatusSnapshot::Zombie => ProcessStatusType::Zombie,
        ProcessStatusSnapshot::Other => ProcessStatusType::Other,
    };

    let resource_stats = ResourceStats {
        cpu_percent: resource_snapshot.cpu_percent,
        memory_bytes: resource_snapshot.memory_bytes,
        uptime_seconds: resource_snapshot.uptime_seconds,
    };
    let process_stats = ProcessStats {
        locks_read_total: process_snapshot.locks_read_total,
        locks_write_total: process_snapshot.locks_write_total,
        cpu_total_seconds: process_snapshot.cpu_total_seconds,
        file_descriptor_limit_total: process_snapshot.file_descriptor_limit_total,
        file_descriptor_open_total: process_snapshot.file_descriptor_open_total,
        go_routine_total: process_snapshot.go_routine_total,
        io_rchar_bytes: process_snapshot.io_rchar_bytes,
        io_read_bytes: process_snapshot.io_read_bytes,
        io_wchar_bytes: process_snapshot.io_wchar_bytes,
        io_write_bytes: process_snapshot.io_write_bytes,
        resident_memory_bytes: process_snapshot.resident_memory_bytes,
        start_time_seconds: process_snapshot.start_time_seconds,
        status,
        status_value: process_snapshot.status_value,
        syscall_read_total: process_snapshot.syscall_read_total,
        syscall_write_total: process_snapshot.syscall_write_total,
        uptime_seconds: process_snapshot.uptime_seconds,
        virtual_memory_bytes: process_snapshot.virtual_memory_bytes,
        virtual_memory_max_bytes: process_snapshot.virtual_memory_max_bytes,
    };

    ProcessMetricBundle {
        resource: resource_stats,
        process: process_stats,
        disk_read_bytes: process_snapshot.disk_read_bytes,
        disk_write_bytes: process_snapshot.disk_write_bytes,
    }
}

/// Collect resource and process statistics for the current process in one sysinfo refresh.
#[inline]
pub fn collect_process_resource_and_system_stats() -> (ResourceStats, ProcessStats) {
    let bundle = collect_process_metric_bundle();
    (bundle.resource, bundle.process)
}

/// Collect resource statistics for the current process.
#[inline]
pub fn collect_process_stats() -> ResourceStats {
    collect_process_metric_bundle().resource
}

/// Collect process statistics for the current process.
#[inline]
pub fn collect_process_system_stats() -> ProcessStats {
    collect_process_metric_bundle().process
}

/// Collect host network statistics from a refreshed network interface snapshot.
///
/// These counters come from system interfaces and are host-wide, not process-scoped.
pub fn collect_host_network_stats_with(networks: &Networks) -> HostNetworkStats {
    let mut total_received = 0u64;
    let mut total_transmitted = 0u64;
    let mut per_interface = Vec::with_capacity(networks.len());

    for (interface_name, data) in networks {
        let received = data.received();
        let transmitted = data.transmitted();
        total_received += received;
        total_transmitted += transmitted;
        per_interface.push((interface_name.to_string(), received, transmitted));
    }

    HostNetworkStats {
        total_received,
        total_transmitted,
        per_interface,
    }
}

/// Collect host network statistics using a persistent `sysinfo::Networks` snapshot.
///
/// `sysinfo` reports network I/O as deltas since the previous refresh, so
/// callers must reuse the same `Networks` instance across collection ticks.
pub fn collect_host_network_stats(networks: &mut Networks) -> HostNetworkStats {
    networks.refresh(true);
    collect_host_network_stats_with(networks)
}

/// Collect internode network metrics from the global internode metrics snapshot.
///
/// The returned values come directly from `global_internode_metrics().snapshot()`
/// and currently include only the counters and dial timing data tracked by the
/// internode metrics runtime.
pub fn collect_internode_network_stats() -> Option<NetworkStats> {
    let snapshot = global_internode_metrics().snapshot();

    Some(NetworkStats {
        internode_errors_total: snapshot.errors_total,
        internode_dial_errors_total: snapshot.dial_errors_total,
        internode_dial_avg_time_nanos: snapshot.dial_avg_time_nanos,
        internode_sent_bytes_total: snapshot.sent_bytes_total,
        internode_recv_bytes_total: snapshot.recv_bytes_total,
    })
}

/// Collect cluster config metrics from backend parity configuration.
fn cluster_config_stats_from_backend_parities(
    rr_sc_parity: Option<usize>,
    standard_sc_parity: Option<usize>,
) -> Option<ClusterConfigStats> {
    Some(ClusterConfigStats {
        rrs_parity: u32::try_from(rr_sc_parity?).ok()?,
        standard_parity: u32::try_from(standard_sc_parity?).ok()?,
    })
}

pub async fn collect_cluster_config_stats() -> Option<ClusterConfigStats> {
    let store = resolve_obs_object_store_handle()?;
    let backend = StorageAdminApi::backend_info(store.as_ref()).await;

    cluster_config_stats_from_backend_parities(backend.rr_sc_parity, backend.standard_sc_parity)
}

fn standard_erasure_layout_from_backend(backend: &ObsBackendInfo, pool_idx: usize) -> Option<(usize, usize)> {
    let drives_per_set = backend.drives_per_set.get(pool_idx).copied()?;
    if drives_per_set == 0
        || (!backend.standard_sc_data.is_empty() && backend.standard_sc_data.len() != backend.drives_per_set.len())
        || (!backend.standard_sc_parities.is_empty() && backend.standard_sc_parities.len() != backend.drives_per_set.len())
    {
        return None;
    }

    let has_data = !backend.standard_sc_data.is_empty();
    let has_parities = !backend.standard_sc_parities.is_empty();
    let (data, parity) = match (has_data, has_parities) {
        (true, true) => (
            backend.standard_sc_data.get(pool_idx).copied()?,
            backend.standard_sc_parities.get(pool_idx).copied()?,
        ),
        (true, false) => {
            let data = backend.standard_sc_data.get(pool_idx).copied()?;
            (data, drives_per_set.checked_sub(data)?)
        }
        (false, true) => {
            let parity = backend.standard_sc_parities.get(pool_idx).copied()?;
            (drives_per_set.checked_sub(parity)?, parity)
        }
        (false, false) => {
            let parity = backend.standard_sc_parity?;
            (drives_per_set.checked_sub(parity)?, parity)
        }
    };

    if data == 0 || parity > data || data.checked_add(parity) != Some(drives_per_set) {
        return None;
    }

    Some((data, parity))
}

fn erasure_set_stats_from_backend(storage_info: &ObsStorageInfo, backend: &ObsBackendInfo) -> Vec<ErasureSetStats> {
    let mut grouped: HashMap<(usize, usize), ErasureSetStats> = HashMap::new();

    for disk in &storage_info.disks {
        let (Ok(pool_idx), Ok(set_idx)) = (usize::try_from(disk.pool_index), usize::try_from(disk.set_index)) else {
            continue;
        };
        let Some((_, parity)) = standard_erasure_layout_from_backend(backend, pool_idx) else {
            continue;
        };
        let set_drive_count = backend.drives_per_set[pool_idx];
        let (Ok(pool_id), Ok(set_id), Ok(size), Ok(parity_metric)) = (
            u32::try_from(pool_idx),
            u32::try_from(set_idx),
            u32::try_from(set_drive_count),
            u32::try_from(parity),
        ) else {
            continue;
        };
        let quorum_shape = derive_erasure_set_quorum_shape(set_drive_count, parity);

        let entry = grouped.entry((pool_idx, set_idx)).or_insert_with(|| ErasureSetStats {
            pool_id,
            set_id,
            size,
            parity: parity_metric,
            data_shards: quorum_shape.data_shards,
            read_quorum: quorum_shape.read_quorum,
            write_quorum: quorum_shape.write_quorum,
            online_drives_count: 0,
            healing_drives_count: 0,
            health: 0,
            read_tolerance: quorum_shape.read_tolerance,
            write_tolerance: quorum_shape.write_tolerance,
            read_health: 0,
            write_health: 0,
        });

        if disk_is_online_for_metrics(disk.state.as_str(), disk.runtime_state.as_deref()) {
            entry.online_drives_count += 1;
        }
        if disk.healing {
            entry.healing_drives_count += 1;
        }
    }

    for entry in grouped.values_mut() {
        apply_erasure_set_health(entry);
    }

    let mut stats = grouped.into_values().collect::<Vec<_>>();
    stats.sort_by_key(|stat| (stat.pool_id, stat.set_id));
    stats
}

/// Collect cluster erasure set metrics from storage and backend topology info.
pub async fn collect_erasure_set_stats() -> Vec<ErasureSetStats> {
    let Some(store) = resolve_obs_object_store_handle() else {
        return Vec::new();
    };

    let storage_info = StorageAdminApi::storage_info(store.as_ref()).await;
    let backend = StorageAdminApi::backend_info(store.as_ref()).await;
    erasure_set_stats_from_backend(&storage_info, &backend)
}

pub async fn collect_iam_stats() -> Option<IamStats> {
    let snapshot = iam_metrics_snapshot()?;

    Some(IamStats {
        last_sync_duration_millis: snapshot.last_sync_duration_millis,
        plugin_authn_service_failed_requests_minute: snapshot.plugin_authn_service_failed_requests_minute,
        plugin_authn_service_last_fail_seconds: snapshot.plugin_authn_service_last_fail_seconds,
        plugin_authn_service_last_succ_seconds: snapshot.plugin_authn_service_last_succ_seconds,
        plugin_authn_service_succ_avg_rtt_ms_minute: snapshot.plugin_authn_service_succ_avg_rtt_ms_minute,
        plugin_authn_service_succ_max_rtt_ms_minute: snapshot.plugin_authn_service_succ_max_rtt_ms_minute,
        plugin_authn_service_total_requests_minute: snapshot.plugin_authn_service_total_requests_minute,
        since_last_sync_millis: snapshot.since_last_sync_millis,
        sync_failures: snapshot.sync_failures,
        sync_successes: snapshot.sync_successes,
    })
}

/// Collect cluster and per-bucket usage metrics from backend usage snapshots.
///
/// This reads persisted usage data via `load_data_usage_from_backend()` and
/// builds cluster totals plus per-bucket distributions from the returned
/// histograms. It does not trigger an inline object-data rescan.
pub async fn collect_cluster_usage_metric_stats() -> Option<(ClusterUsageStats, Vec<BucketUsageStats>)> {
    let store = resolve_obs_object_store_handle()?;
    let data_usage = load_obs_data_usage_from_backend(store.clone()).await.ok()?;
    let mut buckets = Vec::with_capacity(data_usage.buckets_usage.len());

    for (bucket_name, usage) in &data_usage.buckets_usage {
        if bucket_name.starts_with('.') {
            continue;
        }

        let quota_bytes = obs_bucket_quota_limit_bytes(bucket_name).await;

        buckets.push(BucketUsageStats {
            bucket: bucket_name.clone(),
            total_bytes: usage.size,
            objects_count: usage.objects_count,
            versions_count: usage.versions_count,
            delete_markers_count: usage.delete_markers_count,
            quota_bytes,
            object_size_distribution: usage
                .object_size_histogram
                .iter()
                .map(|(range, count)| (range.clone(), *count))
                .collect(),
            version_count_distribution: usage
                .object_versions_histogram
                .iter()
                .map(|(range, count)| (range.clone(), *count))
                .collect(),
        });
    }

    buckets.sort_by(|a, b| a.bucket.cmp(&b.bucket));

    Some((
        ClusterUsageStats {
            since_last_update_seconds: crate::metrics::collectors::cluster_usage::usage_since_last_update_seconds(
                data_usage.last_update,
                SystemTime::now(),
            ),
            total_bytes: data_usage.objects_total_size,
            objects_count: data_usage.objects_total_count,
            versions_count: data_usage.versions_total_count,
            delete_markers_count: data_usage.delete_markers_total_count,
            buckets_count: data_usage.buckets_count,
            object_size_distribution: data_usage
                .buckets_usage
                .values()
                .flat_map(|usage| usage.object_size_histogram.iter())
                .fold(HashMap::<String, u64>::new(), |mut acc, (range, count)| {
                    *acc.entry(range.clone()).or_default() += *count;
                    acc
                })
                .into_iter()
                .collect(),
            versions_distribution: data_usage
                .buckets_usage
                .values()
                .flat_map(|usage| usage.object_versions_histogram.iter())
                .fold(HashMap::<String, u64>::new(), |mut acc, (range, count)| {
                    *acc.entry(range.clone()).or_default() += *count;
                    acc
                })
                .into_iter()
                .collect(),
        },
        buckets,
    ))
}

/// Collect ILM metrics from the current lifecycle runtime state.
pub async fn collect_ilm_metric_stats() -> Option<IlmStats> {
    let ilm = obs_ilm_runtime_snapshot().await;
    let metrics = global_metrics().report().await;
    let versions_scanned = scanner_lifecycle_checked_versions(&metrics);

    Some(IlmStats {
        expiry_pending_tasks: ilm.expiry_pending_tasks,
        transition_active_tasks: ilm.transition_active_tasks,
        transition_pending_tasks: ilm.transition_pending_tasks,
        transition_missed_immediate_tasks: ilm.transition_missed_immediate_tasks,
        transition_queue_full_tasks: ilm.transition_queue_full_tasks,
        transition_queue_send_timeout_tasks: ilm.transition_queue_send_timeout_tasks,
        transition_compensation_scheduled_tasks: ilm.transition_compensation_scheduled_tasks,
        transition_compensation_running_tasks: ilm.transition_compensation_running_tasks,
        versions_scanned,
    })
}

/// Collect scanner metrics from a runtime source.
///
/// Task 5 maps scanner runtime snapshots from `global_metrics()` into the
/// rustfs-obs scanner collector shape.
fn scanner_bucket_scans_started(life_time_ops: &HashMap<String, u64>, bucket_scans_finished: u64) -> u64 {
    life_time_ops
        .get("scan_bucket_drive_start")
        .copied()
        .unwrap_or(bucket_scans_finished)
}

pub async fn collect_scanner_metric_stats() -> Option<ScannerStats> {
    let metrics = global_metrics().report().await;
    let now = Utc::now();
    let bucket_scans_finished = metrics.life_time_ops.get("scan_bucket_drive").copied().unwrap_or_default();
    let bucket_scans_started = scanner_bucket_scans_started(&metrics.life_time_ops, bucket_scans_finished);
    let bucket_scans_failed = metrics
        .life_time_ops
        .get("scan_bucket_drive_failure")
        .copied()
        .unwrap_or_default();
    let completed_cycles = metrics.life_time_ops.get("scan_cycle").copied().unwrap_or_default();
    let directories_scanned = metrics.life_time_ops.get("scan_folder").copied().unwrap_or_default();
    let objects_scanned = metrics.life_time_ops.get("scan_object").copied().unwrap_or_default();
    // Real scan coverage: every version the scanner walked, independent of ILM
    // rules. The ILM-checked subset (`scanner_lifecycle_checked_versions`) still
    // feeds the ILM collector's versions_scanned, but the scanner collector must
    // report the total scanned versions — otherwise clusters without lifecycle
    // rules report zero here while objects_scanned keeps climbing.
    let versions_scanned = metrics.versions_scanned;
    let reference_time = metrics.cycles_completed_at.last().copied().unwrap_or(metrics.current_started);
    let last_activity_seconds = now.signed_duration_since(reference_time).num_seconds().max(0) as u64;
    let active_paths = metrics.active_scan_paths as u64;
    let current_cycle_age_seconds = current_scanner_cycle_age_seconds(metrics.current_cycle, metrics.current_started, now);
    let current_scan_mode = scanner_scan_mode_code(&metrics.current_scan_mode);
    let current_cycle_age = current_cycle_age_seconds as f64;
    let last_cycle_duration = metrics.last_cycle_duration_seconds;

    Some(ScannerStats {
        bucket_scans_finished,
        bucket_scans_started,
        bucket_scans_failed,
        directories_scanned,
        objects_scanned,
        versions_scanned,
        last_activity_seconds,
        active_paths,
        oldest_active_path_age_seconds: metrics.oldest_active_path_age_seconds,
        current_set_scan_concurrency_limit: metrics.current_set_scan_concurrency_limit,
        current_set_scans_queued: metrics.current_set_scans_queued,
        current_set_scans_active: metrics.current_set_scans_active,
        current_disk_scan_concurrency_limit: metrics.current_disk_scan_concurrency_limit,
        current_disk_bucket_scans_queued: metrics.current_disk_bucket_scans_queued,
        current_disk_bucket_scans_active: metrics.current_disk_bucket_scans_active,
        throttle_idle_mode_enabled: metrics.throttle_idle_mode_enabled,
        throttle_sleep_factor: metrics.throttle_sleep_factor,
        throttle_max_sleep_seconds: metrics.throttle_max_sleep_seconds,
        yield_every_n_objects: metrics.yield_every_n_objects,
        cycle_interval_seconds: metrics.cycle_interval_seconds,
        cycle_max_duration_seconds: metrics.cycle_max_duration_seconds,
        cycle_max_objects: metrics.cycle_max_objects,
        cycle_max_directories: metrics.cycle_max_directories,
        bitrot_cycle_enabled: metrics.bitrot_cycle_enabled,
        bitrot_cycle_seconds: metrics.bitrot_cycle_seconds,
        current_cycle: metrics.current_cycle,
        completed_cycles,
        current_cycle_age_seconds,
        current_cycle_objects_scanned: metrics.current_cycle_objects_scanned,
        current_cycle_directories_scanned: metrics.current_cycle_directories_scanned,
        current_cycle_bucket_drive_scans: metrics.current_cycle_bucket_drive_scans,
        current_cycle_bucket_drive_failures: metrics.current_cycle_bucket_drive_failures,
        current_cycle_objects_per_second: scanner_work_rate_per_second(metrics.current_cycle_objects_scanned, current_cycle_age),
        current_cycle_directories_per_second: scanner_work_rate_per_second(
            metrics.current_cycle_directories_scanned,
            current_cycle_age,
        ),
        current_cycle_bucket_drive_scans_per_second: scanner_work_rate_per_second(
            metrics.current_cycle_bucket_drive_scans,
            current_cycle_age,
        ),
        current_cycle_yield_events: metrics.current_cycle_yield_events,
        current_cycle_yield_duration_seconds: metrics.current_cycle_yield_duration_seconds,
        current_cycle_throttle_sleep_events: metrics.current_cycle_throttle_sleep_events,
        current_cycle_throttle_sleep_duration_seconds: metrics.current_cycle_throttle_sleep_duration_seconds,
        current_cycle_ilm_actions: metrics.current_cycle_ilm_actions,
        current_cycle_heal_objects: metrics.current_cycle_heal_objects,
        current_cycle_replication_checks: metrics.current_cycle_replication_checks,
        current_cycle_usage_saves: metrics.current_cycle_usage_saves,
        current_scan_mode,
        last_cycle_result: metrics.last_cycle_result_code,
        last_cycle_partial_reason: metrics.last_cycle_partial_reason_code,
        last_cycle_duration_seconds: metrics.last_cycle_duration_seconds,
        last_cycle_objects_scanned: metrics.last_cycle_objects_scanned,
        last_cycle_directories_scanned: metrics.last_cycle_directories_scanned,
        last_cycle_bucket_drive_scans: metrics.last_cycle_bucket_drive_scans,
        last_cycle_bucket_drive_failures: metrics.last_cycle_bucket_drive_failures,
        last_cycle_objects_per_second: scanner_work_rate_per_second(metrics.last_cycle_objects_scanned, last_cycle_duration),
        last_cycle_directories_per_second: scanner_work_rate_per_second(
            metrics.last_cycle_directories_scanned,
            last_cycle_duration,
        ),
        last_cycle_bucket_drive_scans_per_second: scanner_work_rate_per_second(
            metrics.last_cycle_bucket_drive_scans,
            last_cycle_duration,
        ),
        last_cycle_yield_events: metrics.last_cycle_yield_events,
        last_cycle_yield_duration_seconds: metrics.last_cycle_yield_duration_seconds,
        last_cycle_throttle_sleep_events: metrics.last_cycle_throttle_sleep_events,
        last_cycle_throttle_sleep_duration_seconds: metrics.last_cycle_throttle_sleep_duration_seconds,
        last_cycle_ilm_actions: metrics.last_cycle_ilm_actions,
        last_cycle_heal_objects: metrics.last_cycle_heal_objects,
        last_cycle_replication_checks: metrics.last_cycle_replication_checks,
        last_cycle_usage_saves: metrics.last_cycle_usage_saves,
        failed_cycles: metrics.failed_cycles,
        superseded_cycles: metrics.superseded_cycles,
        partial_cycles: metrics.partial_cycles,
        partial_cycles_unknown: metrics.partial_cycles_unknown,
        partial_cycles_runtime: metrics.partial_cycles_runtime,
        partial_cycles_objects: metrics.partial_cycles_objects,
        partial_cycles_directories: metrics.partial_cycles_directories,
    })
}

/// Collect cluster-level compression statistics.
pub async fn collect_compression_cluster_stats() -> Option<CompressionClusterStats> {
    let compression_data_usage = obs_load_compression_total_from_memory().await?;

    let original_bytes_total = compression_data_usage.original_bytes_total;
    let compressed_bytes_total = compression_data_usage.compressed_bytes_total;
    let bytes_saved_total = original_bytes_total.saturating_sub(compressed_bytes_total);
    let compression_ratio = if original_bytes_total > 0 {
        compressed_bytes_total as f64 / original_bytes_total as f64
    } else {
        0.0
    };
    let compression_operations_total = compression_data_usage.compression_operations_total;

    Some(CompressionClusterStats {
        original_bytes_total,
        compressed_bytes_total,
        bytes_saved_total,
        compression_ratio,
        compression_operations_total,
    })
}
#[cfg(test)]
mod tests {
    use super::*;
    use rustfs_common::metrics::ScannerSourceWorkSnapshot;
    use std::io::{Read, Write};
    use std::net::{Shutdown, TcpListener, TcpStream};
    use std::thread;
    use std::time::Duration;

    fn storage_info_with_one_online_disk() -> ObsStorageInfo {
        let mut info = ObsStorageInfo::default();
        info.disks.push(Default::default());
        let disk = info.disks.last_mut().expect("inserted disk should exist");
        disk.pool_index = 0;
        disk.set_index = 0;
        disk.disk_index = 0;
        disk.state = DRIVE_STATE_OK.to_string();
        disk.runtime_state = Some(DRIVE_STATE_ONLINE.to_string());
        info
    }

    #[test]
    fn cluster_config_stats_accept_homogeneous_backend_parities() {
        let stats = cluster_config_stats_from_backend_parities(Some(1), Some(2))
            .expect("homogeneous scalar parities should produce cluster config metrics");

        assert_eq!(stats.rrs_parity, 1);
        assert_eq!(stats.standard_parity, 2);
    }

    #[test]
    fn cluster_config_stats_skip_heterogeneous_backend_parities() {
        assert!(cluster_config_stats_from_backend_parities(Some(1), None).is_none());
        assert!(cluster_config_stats_from_backend_parities(None, Some(2)).is_none());
    }

    #[test]
    fn cluster_config_stats_reject_parity_larger_than_u32() {
        let Ok(overflow) = usize::try_from(u64::from(u32::MAX) + 1) else {
            return;
        };

        assert!(cluster_config_stats_from_backend_parities(Some(overflow), Some(2)).is_none());
        assert!(cluster_config_stats_from_backend_parities(Some(1), Some(overflow)).is_none());
    }

    #[test]
    fn erasure_set_stats_skip_unknown_backend_layout() {
        let storage_info = storage_info_with_one_online_disk();
        let backend = ObsBackendInfo {
            drives_per_set: vec![8],
            ..Default::default()
        };

        assert!(erasure_set_stats_from_backend(&storage_info, &backend).is_empty());
    }

    #[test]
    fn erasure_set_stats_skip_inconsistent_exact_layout_without_scalar_fallback() {
        let storage_info = storage_info_with_one_online_disk();
        let backend = ObsBackendInfo {
            standard_sc_data: vec![6],
            standard_sc_parities: vec![4],
            standard_sc_parity: Some(2),
            drives_per_set: vec![8],
            ..Default::default()
        };

        assert!(erasure_set_stats_from_backend(&storage_info, &backend).is_empty());
    }

    #[test]
    fn erasure_set_stats_accept_truthful_legacy_scalar_layout() {
        let storage_info = storage_info_with_one_online_disk();
        let backend = ObsBackendInfo {
            standard_sc_parity: Some(2),
            drives_per_set: vec![8],
            ..Default::default()
        };

        let stats = erasure_set_stats_from_backend(&storage_info, &backend);
        assert_eq!(stats.len(), 1);
        assert_eq!(stats[0].size, 8);
        assert_eq!(stats[0].parity, 2);
        assert_eq!(stats[0].data_shards, 6);
    }

    #[test]
    fn erasure_set_stats_exact_data_ignores_stale_scalar() {
        let storage_info = storage_info_with_one_online_disk();
        let backend = ObsBackendInfo {
            standard_sc_data: vec![6],
            standard_sc_parity: Some(4),
            drives_per_set: vec![8],
            ..Default::default()
        };

        let stats = erasure_set_stats_from_backend(&storage_info, &backend);
        assert_eq!(stats.len(), 1);
        assert_eq!(stats[0].parity, 2);
        assert_eq!(stats[0].data_shards, 6);
    }

    fn generate_loopback_traffic() -> std::io::Result<()> {
        let listener = TcpListener::bind(("127.0.0.1", 0))?;
        let addr = listener.local_addr()?;
        let payload = vec![0x5Au8; 64 * 1024];
        let expected_len = payload.len();

        let server = thread::spawn(move || -> std::io::Result<()> {
            let (mut stream, _) = listener.accept()?;
            let mut received = 0usize;
            let mut buf = [0u8; 8192];

            while received < expected_len {
                let read = stream.read(&mut buf)?;
                if read == 0 {
                    break;
                }
                received += read;
            }

            Ok(())
        });

        let mut client = TcpStream::connect(addr)?;
        client.write_all(&payload)?;
        client.flush()?;
        client.shutdown(Shutdown::Write)?;

        server
            .join()
            .expect("loopback traffic server thread should complete successfully")?;
        Ok(())
    }

    #[test]
    fn disk_is_online_for_metrics_accepts_online_state_case_insensitive() {
        assert!(disk_is_online_for_metrics("OnLiNe", Some("online")));
    }

    #[test]
    fn disk_is_online_for_metrics_rejects_offline_runtime_state() {
        assert!(!disk_is_online_for_metrics(DRIVE_STATE_OK, Some("offline")));
    }

    #[test]
    fn derive_erasure_set_quorum_shape_handles_standard_layout() {
        let shape = derive_erasure_set_quorum_shape(16, 4);

        assert_eq!(
            shape,
            ErasureSetQuorumShape {
                data_shards: 12,
                read_quorum: 12,
                write_quorum: 12,
                read_tolerance: 4,
                write_tolerance: 4,
            }
        );
    }

    #[test]
    fn derive_erasure_set_quorum_shape_handles_equal_data_and_parity() {
        let shape = derive_erasure_set_quorum_shape(4, 2);

        assert_eq!(
            shape,
            ErasureSetQuorumShape {
                data_shards: 2,
                read_quorum: 2,
                write_quorum: 3,
                read_tolerance: 2,
                write_tolerance: 1,
            }
        );
    }

    #[test]
    fn apply_erasure_set_health_marks_read_and_write_health_from_online_count() {
        let mut stats = ErasureSetStats {
            read_quorum: 3,
            write_quorum: 4,
            online_drives_count: 3,
            ..Default::default()
        };

        apply_erasure_set_health(&mut stats);
        assert_eq!(stats.read_health, 1);
        assert_eq!(stats.write_health, 0);
        assert_eq!(stats.health, 0);

        stats.online_drives_count = 4;
        apply_erasure_set_health(&mut stats);
        assert_eq!(stats.read_health, 1);
        assert_eq!(stats.write_health, 1);
        assert_eq!(stats.health, 1);
    }

    #[test]
    fn current_scanner_cycle_age_seconds_returns_zero_when_idle() {
        let now = Utc::now();

        assert_eq!(current_scanner_cycle_age_seconds(0, now - chrono::Duration::seconds(30), now), 0);
    }

    #[test]
    fn current_scanner_cycle_age_seconds_clamps_future_start() {
        let now = Utc::now();

        assert_eq!(current_scanner_cycle_age_seconds(4, now + chrono::Duration::seconds(30), now), 0);
    }

    #[test]
    fn current_scanner_cycle_age_seconds_reports_active_elapsed_time() {
        let now = Utc::now();

        assert_eq!(current_scanner_cycle_age_seconds(4, now - chrono::Duration::seconds(45), now), 45);
    }

    #[test]
    fn scanner_scan_mode_code_maps_known_modes() {
        assert_eq!(scanner_scan_mode_code(HealScanMode::Normal.as_str()), HealScanMode::Normal as u8 as u64);
        assert_eq!(scanner_scan_mode_code(HealScanMode::Deep.as_str()), HealScanMode::Deep as u8 as u64);
    }

    #[test]
    fn scanner_scan_mode_code_maps_unknown_mode() {
        assert_eq!(scanner_scan_mode_code(""), HealScanMode::Unknown as u8 as u64);
    }

    #[test]
    fn scanner_bucket_scans_started_uses_explicit_started_count() {
        let mut life_time_ops = HashMap::new();
        life_time_ops.insert("scan_bucket_drive_start".to_string(), 7);

        assert_eq!(scanner_bucket_scans_started(&life_time_ops, 5), 7);
    }

    #[test]
    fn scanner_bucket_scans_started_falls_back_to_finished_count() {
        let life_time_ops = HashMap::new();

        assert_eq!(scanner_bucket_scans_started(&life_time_ops, 5), 5);
    }

    #[test]
    fn scanner_lifecycle_checked_versions_uses_lifecycle_checked_source_work() {
        let report = ScannerMetricsReport {
            source_work: vec![
                ScannerSourceWorkSnapshot {
                    source: "usage".to_string(),
                    checked: 11,
                    ..Default::default()
                },
                ScannerSourceWorkSnapshot {
                    source: "lifecycle".to_string(),
                    checked: 37,
                    ..Default::default()
                },
            ],
            life_time_ilm: HashMap::from([("TransitionAction".to_string(), 5), ("DeleteAction".to_string(), 7)]),
            ..Default::default()
        };

        assert_eq!(scanner_lifecycle_checked_versions(&report), 37);
    }

    #[test]
    fn scanner_lifecycle_checked_versions_defaults_to_zero_when_lifecycle_missing() {
        let report = ScannerMetricsReport {
            source_work: vec![ScannerSourceWorkSnapshot {
                source: "usage".to_string(),
                checked: 11,
                ..Default::default()
            }],
            ..Default::default()
        };

        assert_eq!(scanner_lifecycle_checked_versions(&report), 0);
    }

    #[test]
    fn host_network_stats_require_a_persistent_networks_snapshot() -> std::io::Result<()> {
        if !sysinfo::IS_SUPPORTED_SYSTEM {
            return Ok(());
        }

        let mut persistent_networks = Networks::new();
        persistent_networks.refresh(true);
        let initial_stats = collect_host_network_stats_with(&persistent_networks);
        assert_eq!(
            initial_stats.total_received + initial_stats.total_transmitted,
            0,
            "the first refresh only seeds sysinfo's baseline snapshot"
        );

        match generate_loopback_traffic() {
            Ok(()) => {}
            Err(err) if err.kind() == std::io::ErrorKind::PermissionDenied => {
                return Ok(());
            }
            Err(err) => return Err(err),
        }
        thread::sleep(Duration::from_millis(100));

        let refreshed_stats = collect_host_network_stats(&mut persistent_networks);
        assert!(
            refreshed_stats.total_received > 0 || refreshed_stats.total_transmitted > 0,
            "a persistent Networks instance should report non-zero loopback deltas after traffic"
        );

        let recreated_stats = collect_host_network_stats_with(&Networks::new_with_refreshed_list());
        assert_eq!(
            recreated_stats.total_received + recreated_stats.total_transmitted,
            0,
            "recreating Networks loses the prior refresh baseline and yields zero deltas"
        );
        Ok(())
    }

    #[test]
    fn scanner_work_rate_per_second_reports_rate() {
        assert_eq!(scanner_work_rate_per_second(90, 45.0), 2.0);
    }

    #[test]
    fn scanner_work_rate_per_second_returns_zero_for_invalid_seconds() {
        assert_eq!(scanner_work_rate_per_second(90, 0.0), 0.0);
        assert_eq!(scanner_work_rate_per_second(90, f64::INFINITY), 0.0);
        assert_eq!(scanner_work_rate_per_second(90, f64::NAN), 0.0);
    }

    #[test]
    fn usable_capacity_used_bytes_matches_usable_total_minus_free() {
        assert_eq!(usable_capacity_used_bytes(240, 90), 150);
    }

    #[test]
    fn usable_capacity_used_bytes_saturates_when_free_exceeds_total() {
        assert_eq!(usable_capacity_used_bytes(90, 240), 0);
    }
}