/**
 * User device scope — folder ACL sync, peer grants, effective visibility.
 */

const config = require('../config/config');
const deviceGroupService = require('./deviceGroupService');

function folderGroupGuid(folderId) {
    return `folder_${folderId}`;
}

function normalizeFolderIds(value) {
    const raw = Array.isArray(value) ? value : [];
    return Array.from(new Set(raw.map(v => Number.parseInt(v, 10)).filter(Number.isFinite))).slice(0, 200);
}

function normalizePeerIds(value) {
    const raw = Array.isArray(value) ? value : String(value || '').split(',');
    return Array.from(new Set(raw.map(v => String(v || '').trim()).filter(Boolean))).slice(0, 500);
}

async function ensureFolderMirrorGroup(db, folder) {
    const guid = folderGroupGuid(folder.id);
    const payload = {
        guid,
        name: folder.name,
        note: 'BetterDesk folder access scope',
        source_type: 'manual',
        tag_filter: ''
    };
    let group = await db.getDeviceGroupByGuid(guid);
    if (group) {
        await db.updateDeviceGroup(guid, payload);
        group = await db.getDeviceGroupByGuid(guid);
    } else if (typeof db.createDeviceGroup === 'function') {
        group = await db.createDeviceGroup(payload);
    }
    return group;
}

async function getUserFolderIds(db, username) {
    if (!username || typeof db.getAllFolders !== 'function') return [];
    const folders = await db.getAllFolders();
    const result = [];
    for (const folder of folders || []) {
        const group = await db.getDeviceGroupByGuid(folderGroupGuid(folder.id));
        if (!group) continue;
        const users = deviceGroupService.normalizeUsernames(group.allowed_users);
        if (users.includes(username)) result.push(Number(folder.id));
    }
    return result;
}

async function syncUserFolderAccess(db, username, folderIds) {
    if (!username || typeof db.getAllFolders !== 'function') return [];
    const selected = new Set(normalizeFolderIds(folderIds));
    const folders = await db.getAllFolders();
    for (const folder of folders || []) {
        const group = await ensureFolderMirrorGroup(db, folder);
        if (!group) continue;
        const currentUsers = deviceGroupService.normalizeUsernames(group.allowed_users);
        const wantAccess = selected.has(Number(folder.id));
        const hasAccess = currentUsers.includes(username);
        if (wantAccess && !hasAccess) {
            await db.setDeviceGroupUserAccess(group.guid, [...currentUsers, username]);
        } else if (!wantAccess && hasAccess) {
            await db.setDeviceGroupUserAccess(
                group.guid,
                currentUsers.filter(name => name !== username)
            );
        }
    }
    return Array.from(selected);
}

function peerGrantsUnavailableError(action) {
    const error = new Error(
        `Per-user device grants are unavailable (database.${action} missing). Refusing to silently no-op.`
    );
    error.status = 500;
    error.code = 'PEER_GRANTS_UNAVAILABLE';
    return error;
}

/**
 * Best-effort unknown-device warnings only — never blocks grant persistence.
 * Caps log noise so a large peerIds payload cannot flood the console.
 */
async function warnUnknownPeerIds(db, peerIds) {
    const ids = Array.isArray(peerIds) ? peerIds : [];
    if (!ids.length) return;
    const lookup = typeof db.getPeerById === 'function'
        ? (id) => db.getPeerById(id)
        : typeof db.getDeviceById === 'function'
            ? (id) => db.getDeviceById(id)
            : null;
    if (!lookup) return;

    const maxWarnings = 20;
    let warned = 0;
    for (const peerId of ids) {
        if (warned >= maxWarnings) {
            console.warn(
                `[userScope] peer grant lookup capped after ${maxWarnings} warnings ` +
                `(${ids.length - maxWarnings} remaining unchecked)`
            );
            break;
        }
        try {
            const row = await lookup(peerId);
            if (!row) {
                console.warn('[userScope] peer grant references unknown device id:', peerId);
                warned += 1;
            }
        } catch (err) {
            console.warn('[userScope] peer id lookup failed for', peerId, err.message);
            warned += 1;
        }
    }
}

async function getUserPeerGrantIds(db, userId) {
    if (!userId) return [];
    // Read path stays soft: Users list / enrichment must not 500 if a method is missing.
    if (typeof db.getUserPeerGrants !== 'function') {
        console.error('[userScope] getUserPeerGrants missing on database facade — returning []');
        return [];
    }
    return db.getUserPeerGrants(userId);
}

async function syncUserPeerGrants(db, userId, peerIds) {
    if (!userId) return [];
    // Write path fails closed: never report success while dropping peerIds (#380).
    if (typeof db.setUserPeerGrants !== 'function') {
        throw peerGrantsUnavailableError('setUserPeerGrants');
    }
    const normalized = normalizePeerIds(peerIds);
    await db.setUserPeerGrants(userId, normalized);
    await warnUnknownPeerIds(db, normalized);
    return normalized;
}

async function countEffectiveScope(db, user, devices) {
    const scope = await deviceGroupService.getDeviceScopeForUser(db, user, devices);
    if (scope === null) return { count: (devices || []).length, restricted: false };
    return { count: scope.size, restricted: true };
}

function isDeviceScopeRestrictedDefault() {
    return String(config.deviceScopeDefault || 'open').toLowerCase() === 'restricted';
}

module.exports = {
    folderGroupGuid,
    normalizeFolderIds,
    normalizePeerIds,
    getUserFolderIds,
    syncUserFolderAccess,
    getUserPeerGrantIds,
    syncUserPeerGrants,
    warnUnknownPeerIds,
    countEffectiveScope,
    isDeviceScopeRestrictedDefault
};