/**
 * Database cleanup functions for removing old data based on retention policies.
 *
 * @module lib/db/cleanup
 */

import { getDbInstance } from "./core";
import { getUserDatabaseSettings } from "./databaseSettings";
import { rollupUsageHistoryBeforeDate } from "@/lib/usage/aggregateHistory";
import { purgeCallLogArtifactDirectory } from "@/lib/usage/callLogArtifacts";

interface CleanupResult {
  deleted: number;
  deletedArtifacts?: number;
  errors: number;
}

function getRetentionSettings() {
  return getUserDatabaseSettings().retention;
}

/**
 * Clean up old quota_snapshots based on retention settings.
 */
export async function cleanupQuotaSnapshots(): Promise<CleanupResult> {
  const db = getDbInstance();
  const retention = getRetentionSettings();

  const retentionDays = retention.quotaSnapshots;
  const cutoffDate = new Date();
  cutoffDate.setDate(cutoffDate.getDate() - retentionDays);
  const cutoffISO = cutoffDate.toISOString();

  const result: CleanupResult = { deleted: 0, errors: 0 };

  try {
    const stmt = db.prepare("DELETE FROM quota_snapshots WHERE created_at < ?");
    const runResult = stmt.run(cutoffISO);
    result.deleted = runResult.changes;

    console.log(
      `[Cleanup] Deleted ${result.deleted} quota_snapshots older than ${retentionDays} days`
    );
  } catch (err: unknown) {
    console.error("[Cleanup] Error cleaning quota_snapshots:", err);
    result.errors++;
  }

  return result;
}

/**
 * Clean up old call_logs based on retention settings.
 */
export async function cleanupCallLogs(): Promise<CleanupResult> {
  const db = getDbInstance();
  const retention = getRetentionSettings();

  const retentionDays = retention.callLogs;
  const cutoffDate = new Date();
  cutoffDate.setDate(cutoffDate.getDate() - retentionDays);
  const cutoffISO = cutoffDate.toISOString();

  const result: CleanupResult = { deleted: 0, errors: 0 };

  try {
    const stmt = db.prepare("DELETE FROM call_logs WHERE timestamp < ?");
    const runResult = stmt.run(cutoffISO);
    result.deleted = runResult.changes;

    console.log(`[Cleanup] Deleted ${result.deleted} call_logs older than ${retentionDays} days`);
  } catch (err: unknown) {
    console.error("[Cleanup] Error cleaning call_logs:", err);
    result.errors++;
  }

  return result;
}

/**
 * Clean up old usage_history based on retention settings.
 */
export async function cleanupUsageHistory(): Promise<CleanupResult> {
  const db = getDbInstance();
  const retention = getRetentionSettings();

  const retentionDays = retention.usageHistory;
  const cutoffDate = new Date();
  cutoffDate.setDate(cutoffDate.getDate() - retentionDays);
  const cutoffISO = cutoffDate.toISOString();
  const cutoffDateStr = cutoffISO.split("T")[0];

  const result: CleanupResult = { deleted: 0, errors: 0 };

  // Roll up rows that are about to be deleted into daily_usage_summary so that the
  // analytics route can still surface historical data via the UNION query. The rollup
  // uses the exact same day boundary as the DELETE below, so every deleted row
  // is guaranteed to have been aggregated first.
  //
  // rollupUsageHistoryBeforeDate catches its own errors and reports them via the
  // returned result, so we inspect that rather than relying on a thrown exception.
  // If the rollup failed, abort the DELETE to avoid permanently losing raw usage data
  // that was never aggregated.
  const rollupResult = await rollupUsageHistoryBeforeDate(cutoffDateStr);
  if (rollupResult.errors > 0) {
    console.error(
      "[Cleanup] Aborting usage_history deletion because the pre-delete rollup failed."
    );
    result.errors += rollupResult.errors;
    return result;
  }

  try {
    const stmt = db.prepare("DELETE FROM usage_history WHERE timestamp < ?");
    const runResult = stmt.run(cutoffDateStr);
    result.deleted = runResult.changes;

    console.log(
      `[Cleanup] Deleted ${result.deleted} usage_history older than ${retentionDays} days`
    );
  } catch (err: unknown) {
    console.error("[Cleanup] Error cleaning usage_history:", err);
    result.errors++;
  }

  return result;
}

/**
 * Clean up old compression_analytics based on retention settings.
 */
export async function cleanupCompressionAnalytics(): Promise<CleanupResult> {
  const db = getDbInstance();
  const retention = getRetentionSettings();

  const retentionDays = retention.compressionAnalytics;
  const cutoffDate = new Date();
  cutoffDate.setDate(cutoffDate.getDate() - retentionDays);
  const cutoffISO = cutoffDate.toISOString();

  const result: CleanupResult = { deleted: 0, errors: 0 };

  try {
    const stmt = db.prepare("DELETE FROM compression_analytics WHERE timestamp < ?");
    const runResult = stmt.run(cutoffISO);
    result.deleted = runResult.changes;

    console.log(
      `[Cleanup] Deleted ${result.deleted} compression_analytics older than ${retentionDays} days`
    );
  } catch (err: unknown) {
    console.error("[Cleanup] Error cleaning compression_analytics:", err);
    result.errors++;
  }

  return result;
}

/**
 * Clean up old mcp_audit_log based on retention settings.
 */
export async function cleanupMcpAudit(): Promise<CleanupResult> {
  const db = getDbInstance();
  const retention = getRetentionSettings();

  const retentionDays = retention.mcpAudit;
  const cutoffDate = new Date();
  cutoffDate.setDate(cutoffDate.getDate() - retentionDays);
  const cutoffISO = cutoffDate.toISOString();

  const result: CleanupResult = { deleted: 0, errors: 0 };

  try {
    const stmt = db.prepare("DELETE FROM mcp_tool_audit WHERE timestamp < ?");
    const runResult = stmt.run(cutoffISO);
    result.deleted = runResult.changes;

    console.log(
      `[Cleanup] Deleted ${result.deleted} mcp_audit_log older than ${retentionDays} days`
    );
  } catch (err: unknown) {
    console.error("[Cleanup] Error cleaning mcp_audit_log:", err);
    result.errors++;
  }

  return result;
}

/**
 * Clean up old a2a_events based on retention settings.
 */
export async function cleanupA2aEvents(): Promise<CleanupResult> {
  const db = getDbInstance();
  const retention = getRetentionSettings();

  const retentionDays = retention.a2aEvents;
  const cutoffDate = new Date();
  cutoffDate.setDate(cutoffDate.getDate() - retentionDays);
  const cutoffISO = cutoffDate.toISOString();

  const result: CleanupResult = { deleted: 0, errors: 0 };

  try {
    const stmt = db.prepare("DELETE FROM a2a_task_events WHERE timestamp < ?");
    const runResult = stmt.run(cutoffISO);
    result.deleted = runResult.changes;

    console.log(`[Cleanup] Deleted ${result.deleted} a2a_events older than ${retentionDays} days`);
  } catch (err: unknown) {
    console.error("[Cleanup] Error cleaning a2a_events:", err);
    result.errors++;
  }

  return result;
}

/**
 * Clean up old memory_entries based on retention settings.
 */
export async function cleanupMemoryEntries(): Promise<CleanupResult> {
  const db = getDbInstance();
  const retention = getRetentionSettings();

  const retentionDays = retention.memoryEntries;
  const cutoffDate = new Date();
  cutoffDate.setDate(cutoffDate.getDate() - retentionDays);
  const cutoffISO = cutoffDate.toISOString();

  const result: CleanupResult = { deleted: 0, errors: 0 };

  try {
    const stmt = db.prepare("DELETE FROM memories WHERE created_at < ?");
    const runResult = stmt.run(cutoffISO);
    result.deleted = runResult.changes;

    console.log(
      `[Cleanup] Deleted ${result.deleted} memory_entries older than ${retentionDays} days`
    );
  } catch (err: unknown) {
    console.error("[Cleanup] Error cleaning memory_entries:", err);
    result.errors++;
  }

  return result;
}

/**
 * Run all cleanup functions if auto-cleanup is enabled.
 */
export async function runAutoCleanup(): Promise<{
  totalDeleted: number;
  totalErrors: number;
  results: Record<string, CleanupResult>;
}> {
  const retention = getRetentionSettings();
  const autoCleanupEnabled = retention.autoCleanupEnabled;

  if (!autoCleanupEnabled) {
    console.log("[Cleanup] Auto-cleanup is disabled");
    return { totalDeleted: 0, totalErrors: 0, results: {} };
  }

  console.log("[Cleanup] Starting auto-cleanup...");

  const results: Record<string, CleanupResult> = {
    quotaSnapshots: await cleanupQuotaSnapshots(),
    callLogs: await cleanupCallLogs(),
    usageHistory: await cleanupUsageHistory(),
    compressionAnalytics: await cleanupCompressionAnalytics(),
    mcpAudit: await cleanupMcpAudit(),
    a2aEvents: await cleanupA2aEvents(),
    memoryEntries: await cleanupMemoryEntries(),
    proxyLogs: await cleanupProxyLogs(),
  };

  const totalDeleted = Object.values(results).reduce((sum, r) => sum + r.deleted, 0);
  const totalErrors = Object.values(results).reduce((sum, r) => sum + r.errors, 0);

  console.log(`[Cleanup] Auto-cleanup complete: ${totalDeleted} deleted, ${totalErrors} errors`);

  return { totalDeleted, totalErrors, results };
}

/**
 * Purge ALL quota_snapshots immediately (no retention check).
 */
export async function purgeQuotaSnapshots(): Promise<CleanupResult> {
  const db = getDbInstance();
  const result: CleanupResult = { deleted: 0, errors: 0 };

  try {
    const stmt = db.prepare("DELETE FROM quota_snapshots");
    const runResult = stmt.run();
    result.deleted = runResult.changes;

    console.log(`[Cleanup] Purged ${result.deleted} quota_snapshots`);
  } catch (err: unknown) {
    console.error("[Cleanup] Error purging quota_snapshots:", err);
    result.errors++;
  }

  return result;
}

/**
 * Purge ALL call_logs immediately (no retention check).
 */
export async function purgeCallLogs(): Promise<CleanupResult> {
  const db = getDbInstance();
  const result: CleanupResult = { deleted: 0, deletedArtifacts: 0, errors: 0 };

  try {
    const runResult = db.prepare("DELETE FROM call_logs").run();
    result.deleted = runResult.changes;

    console.log(`[Cleanup] Purged ${result.deleted} call_logs`);
  } catch (err: unknown) {
    console.error("[Cleanup] Error purging call_logs:", err);
    result.errors++;
  }

  const artifactResult = purgeCallLogArtifactDirectory();
  result.deletedArtifacts = artifactResult.deletedArtifacts;
  result.errors += artifactResult.errors;

  if (artifactResult.errors === 0) {
    console.log(`[Cleanup] Purged ${result.deletedArtifacts} call log artifact(s)`);
  }

  return result;
}

/**
 * Purge ALL request_detail_logs immediately (no retention check).
 */
export async function purgeDetailedLogs(): Promise<CleanupResult> {
  const db = getDbInstance();
  const result: CleanupResult = { deleted: 0, errors: 0 };

  try {
    const stmt = db.prepare("DELETE FROM request_detail_logs");
    const runResult = stmt.run();
    result.deleted = runResult.changes;

    console.log(`[Cleanup] Purged ${result.deleted} request_detail_logs`);
  } catch (err: unknown) {
    console.error("[Cleanup] Error purging request_detail_logs:", err);
    result.errors++;
  }

  return result;
}

/**
 * Clean up old proxy_logs based on retention settings.
 * Uses the same retention period as call_logs (30 days default).
 */
export async function cleanupProxyLogs(): Promise<CleanupResult> {
  const db = getDbInstance();
  const retention = getRetentionSettings();

  const retentionDays = retention.callLogs;
  const cutoffDate = new Date();
  cutoffDate.setDate(cutoffDate.getDate() - retentionDays);
  const cutoffISO = cutoffDate.toISOString();

  const result: CleanupResult = { deleted: 0, errors: 0 };

  try {
    const stmt = db.prepare("DELETE FROM proxy_logs WHERE timestamp < ?");
    const runResult = stmt.run(cutoffISO);
    result.deleted = runResult.changes;

    console.log(
      `[Cleanup] Deleted ${result.deleted} proxy_logs older than ${retentionDays} days`
    );
  } catch (err: unknown) {
    console.error("[Cleanup] Error cleaning proxy_logs:", err);
    result.errors++;
  }

  return result;
}

// ──────────────── Background Cleanup Scheduler ────────────────

const CLEANUP_INTERVAL_MS = 6 * 60 * 60 * 1000; // 6 hours
let _cleanupSchedulerTimer: ReturnType<typeof setInterval> | null = null;

/**
 * Start the background cleanup scheduler. Runs cleanup on startup
 * and then every 6 hours. Runs VACUUM after deletes to reclaim disk space.
 *
 * Without this, tables grow unboundedly (compression_analytics 600K+ rows,
 * usage_history 250K+ rows) causing 1.4GB+ SQLite files and 3-8GB RSS
 * from better-sqlite3 memory mapping.
 */
export function startCleanupScheduler(): void {
  if (_cleanupSchedulerTimer) return;

  // Run cleanup 30s after startup (let the server initialize first).
  setTimeout(async () => {
    try {
      const result = await runAutoCleanup();
      const proxyResult = await cleanupProxyLogs();
      const totalDeleted = result.totalDeleted + proxyResult.deleted;
      if (totalDeleted > 0) {
        console.log(
          `[Cleanup] Startup cleanup freed ${totalDeleted} rows. Running VACUUM...`
        );
        try {
          const db = getDbInstance();
          db.exec("VACUUM");
          console.log("[Cleanup] VACUUM completed after startup cleanup.");
        } catch (vacErr) {
          console.error("[Cleanup] VACUUM after cleanup failed:", vacErr);
        }
      }
    } catch (err) {
      console.error("[Cleanup] Startup cleanup failed:", err);
    }
  }, 30_000);

  // Schedule periodic cleanup every 6 hours.
  _cleanupSchedulerTimer = setInterval(async () => {
    try {
      const result = await runAutoCleanup();
      const proxyResult = await cleanupProxyLogs();
      const totalDeleted = result.totalDeleted + proxyResult.deleted;
      if (totalDeleted > 0) {
        console.log(
          `[Cleanup] Periodic cleanup freed ${totalDeleted} rows. Running VACUUM...`
        );
        try {
          const db = getDbInstance();
          db.exec("VACUUM");
          console.log("[Cleanup] VACUUM completed after periodic cleanup.");
        } catch (vacErr) {
          console.error("[Cleanup] VACUUM after cleanup failed:", vacErr);
        }
      }
    } catch (err) {
      console.error("[Cleanup] Periodic cleanup failed:", err);
    }
  }, CLEANUP_INTERVAL_MS);

  // Don't keep the process alive solely for cleanup.
  if (_cleanupSchedulerTimer && typeof _cleanupSchedulerTimer.unref === "function") {
    _cleanupSchedulerTimer.unref();
  }

  console.log("[Cleanup] Background cleanup scheduler started (every 6 hours).");
}

/**
 * Stop the background cleanup scheduler (for tests).
 */
export function stopCleanupScheduler(): void {
  if (_cleanupSchedulerTimer) {
    clearInterval(_cleanupSchedulerTimer);
    _cleanupSchedulerTimer = null;
  }
}