// 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.

use crate::ReplicationTagFilter;
use crate::ReplicationType;
use crate::rule::ReplicationRuleExt as _;
use s3s::dto::DeleteMarkerReplicationStatus;
use s3s::dto::DeleteReplicationStatus;
use s3s::dto::Destination;
use s3s::dto::{ExistingObjectReplicationStatus, ReplicationConfiguration, ReplicationRuleStatus, ReplicationRules};
use serde::{Deserialize, Serialize};
use std::collections::HashSet;
use uuid::Uuid;

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub struct ObjectOpts {
    pub name: String,
    pub user_tags: String,
    pub version_id: Option<Uuid>,
    pub delete_marker: bool,
    pub ssec: bool,
    pub op_type: ReplicationType,
    pub replica: bool,
    pub existing_object: bool,
    pub target_arn: String,
}

pub trait ReplicationConfigurationExt {
    fn replicate(&self, opts: &ObjectOpts) -> bool;
    fn has_existing_object_replication(&self, arn: &str) -> (bool, bool);
    fn filter_actionable_rules(&self, obj: &ObjectOpts) -> ReplicationRules;
    fn get_destination(&self) -> Destination;
    fn has_active_rules(&self, prefix: &str, recursive: bool) -> bool;
    fn filter_target_arns(&self, obj: &ObjectOpts) -> Vec<String>;
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ReplicationTargetValidationError {
    RoleWithMultipleDestinations,
    StaleTarget,
}

pub fn active_replication_rule_destination_arns(config: &ReplicationConfiguration) -> HashSet<String> {
    let mut arns = HashSet::new();

    for rule in &config.rules {
        if rule.status == ReplicationRuleStatus::from_static(ReplicationRuleStatus::DISABLED) {
            continue;
        }

        let arn = rule.destination.bucket.trim();
        if !arn.is_empty() {
            arns.insert(arn.to_string());
        }
    }

    arns
}

pub fn replication_target_arns(config: &ReplicationConfiguration) -> HashSet<String> {
    let role = config.role.trim();
    if !role.is_empty() {
        return HashSet::from([role.to_string()]);
    }

    active_replication_rule_destination_arns(config)
}

pub fn validate_replication_config_target_arns<'a>(
    configured_arns: impl IntoIterator<Item = &'a str>,
    config: &ReplicationConfiguration,
) -> std::result::Result<(), ReplicationTargetValidationError> {
    let configured_arns = configured_arns.into_iter().collect::<HashSet<_>>();

    let role = config.role.trim();
    let destination_arns = active_replication_rule_destination_arns(config);
    if !role.is_empty() && destination_arns.len() > 1 {
        return Err(ReplicationTargetValidationError::RoleWithMultipleDestinations);
    }

    for configured_arn in replication_target_arns(config) {
        if !configured_arns.contains(configured_arn.as_str()) {
            return Err(ReplicationTargetValidationError::StaleTarget);
        }
    }

    Ok(())
}

pub fn should_remove_replication_target(
    target_arn: &str,
    is_replication_target: bool,
    config_target_arns: &HashSet<String>,
) -> bool {
    is_replication_target && config_target_arns.contains(target_arn)
}

impl ReplicationConfigurationExt for ReplicationConfiguration {
    /// Check whether any object-replication rules exist
    fn has_existing_object_replication(&self, arn: &str) -> (bool, bool) {
        let mut has_arn = false;
        let arn = arn.trim();

        for rule in &self.rules {
            if rule.destination.bucket.trim() == arn || self.role.trim() == arn {
                if !has_arn {
                    has_arn = true;
                }
                if let Some(status) = &rule.existing_object_replication
                    && status.status == ExistingObjectReplicationStatus::from_static(ExistingObjectReplicationStatus::ENABLED)
                {
                    return (true, true);
                }
            }
        }
        (has_arn, false)
    }

    fn filter_actionable_rules(&self, obj: &ObjectOpts) -> ReplicationRules {
        if obj.name.is_empty() && obj.op_type != ReplicationType::Resync && obj.op_type != ReplicationType::All {
            return vec![];
        }

        let mut rules = ReplicationRules::default();

        for rule in &self.rules {
            if rule.status == ReplicationRuleStatus::from_static(ReplicationRuleStatus::DISABLED) {
                continue;
            }

            if !obj.target_arn.is_empty()
                && rule.destination.bucket.trim() != obj.target_arn.trim()
                && self.role.trim() != obj.target_arn.trim()
            {
                continue;
            }

            if obj.op_type == ReplicationType::Resync || obj.op_type == ReplicationType::All {
                rules.push(rule.clone());
                continue;
            }

            if let Some(status) = &rule.existing_object_replication
                && obj.existing_object
                && status.status == ExistingObjectReplicationStatus::from_static(ExistingObjectReplicationStatus::DISABLED)
            {
                continue;
            }

            if !obj.name.starts_with(rule.prefix()) {
                continue;
            }

            if let Some(filter) = &rule.filter {
                let object_tags = ReplicationTagFilter::decode_tags_to_map(&obj.user_tags);
                if filter.test_tags(&object_tags) {
                    rules.push(rule.clone());
                }
            } else {
                rules.push(rule.clone());
            }
        }

        rules.sort_by(|a, b| {
            if a.destination == b.destination {
                a.priority.cmp(&b.priority)
            } else {
                std::cmp::Ordering::Equal
            }
        });

        rules
    }

    /// Retrieve the destination configuration
    fn get_destination(&self) -> Destination {
        if !self.rules.is_empty() {
            self.rules[0].destination.clone()
        } else {
            Destination {
                bucket: String::new(),
                ..Default::default()
            }
        }
    }

    /// Determine whether an object should be replicated
    fn replicate(&self, obj: &ObjectOpts) -> bool {
        let rules = self.filter_actionable_rules(obj);

        for rule in rules.iter() {
            if rule.status == ReplicationRuleStatus::from_static(ReplicationRuleStatus::DISABLED) {
                continue;
            }

            if let Some(status) = &rule.existing_object_replication
                && obj.existing_object
                && status.status == ExistingObjectReplicationStatus::from_static(ExistingObjectReplicationStatus::DISABLED)
            {
                return false;
            }

            if obj.op_type == ReplicationType::Delete {
                if !rule.metadata_replicate(obj) {
                    return false;
                }

                if obj.version_id.is_some() {
                    if obj.delete_marker {
                        return rule.delete_marker_replication.clone().is_some_and(|d| {
                            d.status == Some(DeleteMarkerReplicationStatus::from_static(DeleteMarkerReplicationStatus::ENABLED))
                        });
                    }
                    return rule
                        .delete_replication
                        .clone()
                        .is_some_and(|d| d.status == DeleteReplicationStatus::from_static(DeleteReplicationStatus::ENABLED));
                } else {
                    return rule.delete_marker_replication.clone().is_some_and(|d| {
                        d.status == Some(DeleteMarkerReplicationStatus::from_static(DeleteMarkerReplicationStatus::ENABLED))
                    });
                }
            }

            // Regular object/metadata replication
            return rule.metadata_replicate(obj);
        }
        false
    }

    /// Check for an active rule
    /// Optionally accept a prefix
    /// When recursive is true, return true if any level under the prefix has an active rule
    /// Without a prefix, recursive behaves as true
    fn has_active_rules(&self, prefix: &str, recursive: bool) -> bool {
        if self.rules.is_empty() {
            return false;
        }

        for rule in &self.rules {
            if rule.status == ReplicationRuleStatus::from_static(ReplicationRuleStatus::DISABLED) {
                continue;
            }

            if let Some(filter) = &rule.filter
                && let Some(filter_prefix) = &filter.prefix
            {
                if !prefix.is_empty() && !filter_prefix.is_empty() {
                    // The provided prefix must fall within the rule prefix
                    if !recursive && !prefix.starts_with(filter_prefix) {
                        continue;
                    }
                }

                // When recursive, skip this rule if it does not match the test prefix or hierarchy
                if recursive && !rule.prefix().starts_with(prefix) && !prefix.starts_with(rule.prefix()) {
                    continue;
                }
            }
            return true;
        }
        false
    }

    /// Filter target ARNs and return a slice of the distinct values in the config
    fn filter_target_arns(&self, obj: &ObjectOpts) -> Vec<String> {
        let role = self.role.trim();
        if !role.is_empty() {
            return vec![role.to_string()];
        }

        let mut arns = Vec::new();
        let mut targets_map: HashSet<String> = HashSet::new();
        let rules = self.filter_actionable_rules(obj);

        for rule in rules {
            if rule.status == ReplicationRuleStatus::from_static(ReplicationRuleStatus::DISABLED) {
                continue;
            }

            let arn = rule.destination.bucket.trim();
            if !arn.is_empty() && !targets_map.contains(arn) {
                targets_map.insert(arn.to_string());
            }
        }

        for arn in targets_map {
            arns.push(arn);
        }
        arns
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use s3s::dto::{DeleteMarkerReplication, Destination, ExistingObjectReplication, ReplicationRule};

    fn replication_rule(id: &str, arn: &str) -> ReplicationRule {
        ReplicationRule {
            delete_marker_replication: Some(DeleteMarkerReplication::default()),
            delete_replication: None,
            destination: Destination {
                bucket: arn.to_string(),
                ..Default::default()
            },
            existing_object_replication: Some(ExistingObjectReplication {
                status: ExistingObjectReplicationStatus::from_static(ExistingObjectReplicationStatus::ENABLED),
            }),
            filter: None,
            id: Some(id.to_string()),
            prefix: Some(String::new()),
            priority: Some(1),
            source_selection_criteria: None,
            status: ReplicationRuleStatus::from_static(ReplicationRuleStatus::ENABLED),
        }
    }

    #[test]
    fn filter_target_arns_uses_role_when_role_is_present() {
        let config = ReplicationConfiguration {
            role: " arn:legacy:target ".to_string(),
            rules: vec![
                replication_rule("rule-1", "arn:target:a"),
                replication_rule("rule-2", "arn:target:b"),
            ],
        };

        let arns = config.filter_target_arns(&ObjectOpts {
            name: "object".to_string(),
            op_type: ReplicationType::Object,
            ..Default::default()
        });

        assert_eq!(arns, vec!["arn:legacy:target".to_string()]);
    }

    #[test]
    fn filter_target_arns_falls_back_to_role_when_destination_is_empty() {
        let config = ReplicationConfiguration {
            role: "arn:legacy:target".to_string(),
            rules: vec![ReplicationRule {
                delete_marker_replication: Some(DeleteMarkerReplication::default()),
                delete_replication: None,
                destination: Destination {
                    bucket: String::new(),
                    ..Default::default()
                },
                existing_object_replication: Some(ExistingObjectReplication {
                    status: ExistingObjectReplicationStatus::from_static(ExistingObjectReplicationStatus::ENABLED),
                }),
                filter: None,
                id: Some("rule-1".to_string()),
                prefix: Some(String::new()),
                priority: Some(1),
                source_selection_criteria: None,
                status: ReplicationRuleStatus::from_static(ReplicationRuleStatus::ENABLED),
            }],
        };

        let arns = config.filter_target_arns(&ObjectOpts {
            name: "object".to_string(),
            op_type: ReplicationType::Object,
            ..Default::default()
        });

        assert_eq!(arns, vec!["arn:legacy:target".to_string()]);
    }

    fn replication_rule_existing_object_disabled(id: &str, arn: &str) -> ReplicationRule {
        ReplicationRule {
            delete_marker_replication: Some(DeleteMarkerReplication::default()),
            delete_replication: None,
            destination: Destination {
                bucket: arn.to_string(),
                ..Default::default()
            },
            existing_object_replication: Some(ExistingObjectReplication {
                status: ExistingObjectReplicationStatus::from_static(ExistingObjectReplicationStatus::DISABLED),
            }),
            filter: None,
            id: Some(id.to_string()),
            prefix: Some(String::new()),
            priority: Some(1),
            source_selection_criteria: None,
            status: ReplicationRuleStatus::from_static(ReplicationRuleStatus::ENABLED),
        }
    }

    // Regression test for BUG-3: replicate_object was calling filter_target_arns with
    // existing_object:false regardless of op_type, letting ExistingObject resync operations
    // fan out to targets whose rule has ExistingObjectReplicationStatus::DISABLED.
    #[test]
    fn filter_target_arns_excludes_disabled_existing_object_target_for_existing_object_op() {
        let config = ReplicationConfiguration {
            role: String::new(),
            rules: vec![
                replication_rule("rule-enabled", "arn:target:enabled"),
                replication_rule_existing_object_disabled("rule-disabled", "arn:target:disabled"),
            ],
        };

        let arns = config.filter_target_arns(&ObjectOpts {
            name: "object".to_string(),
            op_type: ReplicationType::ExistingObject,
            existing_object: true,
            ..Default::default()
        });

        assert_eq!(arns.len(), 1, "only the ENABLED target should be returned for ExistingObject ops");
        assert!(arns.contains(&"arn:target:enabled".to_string()));
        assert!(!arns.contains(&"arn:target:disabled".to_string()));
    }

    // Heal operations intentionally bypass ExistingObjectReplicationStatus — healing a past
    // failure is not subject to the existing-object opt-out.
    #[test]
    fn filter_target_arns_includes_disabled_existing_object_target_for_heal_op() {
        let config = ReplicationConfiguration {
            role: String::new(),
            rules: vec![
                replication_rule("rule-enabled", "arn:target:enabled"),
                replication_rule_existing_object_disabled("rule-disabled", "arn:target:disabled"),
            ],
        };

        let arns = config.filter_target_arns(&ObjectOpts {
            name: "object".to_string(),
            op_type: ReplicationType::Heal,
            existing_object: false,
            ..Default::default()
        });

        assert_eq!(
            arns.len(),
            2,
            "Heal ops must reach all targets regardless of existing_object_replication setting"
        );
        assert!(arns.contains(&"arn:target:enabled".to_string()));
        assert!(arns.contains(&"arn:target:disabled".to_string()));
    }

    #[test]
    fn replication_target_arns_use_role_when_present() {
        let role = "arn:rustfs:replication:us-east-1:source:bucket";
        let destination = "arn:rustfs:replication:us-east-1:target:bucket";
        let config = ReplicationConfiguration {
            role: format!(" {role} "),
            rules: vec![replication_rule("rule-1", destination)],
        };

        let arns = replication_target_arns(&config);

        assert!(arns.contains(role));
        assert!(!arns.contains(destination));
    }

    #[test]
    fn replication_target_arns_use_rule_destinations_without_role() {
        let destination = "arn:rustfs:replication:us-east-1:target:bucket";
        let config = ReplicationConfiguration {
            role: String::new(),
            rules: vec![replication_rule("rule-1", destination)],
        };

        let arns = replication_target_arns(&config);

        assert!(arns.contains(destination));
    }

    #[test]
    fn validate_replication_config_target_arns_accepts_matching_destination_arns() {
        let arn = "arn:rustfs:replication:us-east-1:target:bucket";
        let config = ReplicationConfiguration {
            role: String::new(),
            rules: vec![replication_rule("rule-1", arn)],
        };

        validate_replication_config_target_arns([arn], &config).expect("matching target should pass validation");
    }

    #[test]
    fn validate_replication_config_target_arns_rejects_stale_destination_arns() {
        let config = ReplicationConfiguration {
            role: String::new(),
            rules: vec![replication_rule("rule-1", "arn:rustfs:replication:us-east-1:target-b:bucket")],
        };

        let err = validate_replication_config_target_arns(["arn:rustfs:replication:us-east-1:target-a:bucket"], &config)
            .expect_err("stale target should fail validation");
        assert_eq!(err, ReplicationTargetValidationError::StaleTarget);
    }

    #[test]
    fn validate_replication_config_target_arns_rejects_role_with_multiple_destinations() {
        let role = "arn:rustfs:replication:us-east-1:role-target:bucket";
        let config = ReplicationConfiguration {
            role: role.to_string(),
            rules: vec![
                replication_rule("rule-a", "arn:rustfs:replication:us-east-1:target-a:bucket"),
                replication_rule("rule-b", "arn:rustfs:replication:us-east-1:target-b:bucket"),
            ],
        };

        let err = validate_replication_config_target_arns([role], &config)
            .expect_err("role plus multiple destinations should be rejected");
        assert_eq!(err, ReplicationTargetValidationError::RoleWithMultipleDestinations);
    }

    #[test]
    fn validate_replication_config_target_arns_ignores_disabled_rules() {
        let mut rule = replication_rule("rule-1", "arn:rustfs:replication:us-east-1:stale:bucket");
        rule.status = ReplicationRuleStatus::from_static(ReplicationRuleStatus::DISABLED);
        let config = ReplicationConfiguration {
            role: String::new(),
            rules: vec![rule],
        };

        validate_replication_config_target_arns(std::iter::empty::<&str>(), &config)
            .expect("disabled rules should not require live targets");
    }

    #[test]
    fn should_remove_replication_target_only_matches_replication_target_arns() {
        let target_arns = HashSet::from(["arn:rustfs:replication:us-east-1:removed:bucket".to_string()]);

        assert!(should_remove_replication_target(
            "arn:rustfs:replication:us-east-1:removed:bucket",
            true,
            &target_arns
        ));
        assert!(!should_remove_replication_target(
            "arn:rustfs:replication:us-east-1:kept:bucket",
            true,
            &target_arns
        ));
        assert!(!should_remove_replication_target(
            "arn:rustfs:replication:us-east-1:removed:bucket",
            false,
            &target_arns
        ));
    }
}