const express = require('express');
const router = express.Router();
const fs = require('fs');
const path = require('path');
const platformPaths = require('../platform-paths');

// DC-048 — the canonical disk-settings.json path. Shared by GET + POST.
function getSettingsFile() {
  return path.join(platformPaths.dataDir, 'disk-settings.json');
}

// GET current disk settings + actual disk usage
router.get('/', (req, res) => {
  try {
    const settings = {
      healthCheckInterval: parseInt(process.env.HEALTH_CHECK_INTERVAL || '30000'),
      healthMaxEntries: parseInt(process.env.HEALTH_MAX_ENTRIES || '500'),
      // DC-048 — align route default to engine default (health-checker.js:34
      // reads 30 from env when unset; the route previously showed 14 as the
      // "no override" value, which silently disagreed with the engine).
      healthRetentionDays: parseInt(process.env.HEALTH_HISTORY_RETENTION || '30'),
      statsMaxEntries: parseInt(process.env.CONTAINER_STATS_MAX_ENTRIES || '500'),
      auditMaxEntries: parseInt(process.env.AUDIT_MAX_ENTRIES || '1000'),
      backupMaxStorageBytes: parseInt(process.env.BACKUP_MAX_STORAGE_BYTES || '0'),
    };

    // Get actual disk usage
    let diskUsage = { total: 0, used: 0, free: 0, dataDirSize: 0 };
    try {
      const { execSync } = require('child_process');
      const dfOut = execSync("df -B1 /opt/dashcaddy/dashcaddy-api/data 2>/dev/null || df -B1 / 2>/dev/null").toString().trim().split('\n');
      if (dfOut.length > 1) {
        const parts = dfOut[1].split(/\s+/);
        diskUsage.total = parseInt(parts[1]) || 0;
        diskUsage.used = parseInt(parts[2]) || 0;
        diskUsage.free = parseInt(parts[3]) || 0;
      }
      const duOut = execSync("du -sb /opt/dashcaddy/dashcaddy-api/data 2>/dev/null || echo 0").toString().trim().split(/\s+/);
      diskUsage.dataDirSize = parseInt(duOut[0]) || 0;
    } catch {}

    // Load persisted settings
    const settingsFile = getSettingsFile();
    let persisted = {};
    try { persisted = JSON.parse(fs.readFileSync(settingsFile, 'utf8')); } catch {}
    
    res.json({ success: true, current: { ...settings, ...persisted }, diskUsage });
  } catch (e) {
    res.status(500).json({ success: false, error: e.message });
  }
});

// POST update settings
router.post('/', (req, res) => {
  try {
    const { healthInterval, healthMaxEntries, healthRetentionDays, statsMaxEntries, auditMaxEntries } = req.body;

    // DC-048 — coerce + validate EVERY numeric input before persisting.
    // Without this gate, parseInt('abc') === NaN → String(NaN) === 'NaN' →
    // process.env.HEALTH_CHECK_INTERVAL becomes 'NaN' at runtime AND the
    // persisted file gets JSON.stringify({x: NaN}) === {"x": null} which
    // the loader silently drops on next boot. Validation now rejects the
    // request with 400 BEFORE any env mutation or file write.
    const intField = (name, value) => {
      const n = Number(value);
      if (!Number.isFinite(n) || !Number.isInteger(n)) {
        throw new Error(`${name} must be an integer (received ${JSON.stringify(value)})`);
      }
      return n;
    };

    const updates = {};
    if (healthInterval !== undefined)      { const n = intField('healthInterval', healthInterval);      updates.healthCheckInterval = n; process.env.HEALTH_CHECK_INTERVAL = String(n); }
    if (healthMaxEntries !== undefined)    { const n = intField('healthMaxEntries', healthMaxEntries);    updates.healthMaxEntries = n;    process.env.HEALTH_MAX_ENTRIES = String(n); }
    if (healthRetentionDays !== undefined) { const n = intField('healthRetentionDays', healthRetentionDays); updates.healthRetentionDays = n; process.env.HEALTH_HISTORY_RETENTION = String(n); }
    if (statsMaxEntries !== undefined)     { const n = intField('statsMaxEntries', statsMaxEntries);     updates.statsMaxEntries = n;     process.env.CONTAINER_STATS_MAX_ENTRIES = String(n); }
    if (auditMaxEntries !== undefined)     { const n = intField('auditMaxEntries', auditMaxEntries);     updates.auditMaxEntries = n;     process.env.AUDIT_MAX_ENTRIES = String(n); }

    // Persist to file
    const settingsFile = getSettingsFile();
    let existing = {};
    try { existing = JSON.parse(fs.readFileSync(settingsFile, 'utf8')); } catch {}
    fs.writeFileSync(settingsFile, JSON.stringify({ ...existing, ...updates }, null, 2));

    res.json({ success: true, updated: updates, message: 'Settings saved. Some changes apply on next container restart.' });
  } catch (e) {
    res.status(e.statusCode || 400).json({ success: false, error: e.message });
  }
});

// POST trigger immediate cleanup
router.post('/cleanup', async (req, res) => {
  try {
    const results = { cleaned: {} };
    
    // Clean health history
    try {
      const healthChecker = require('../monitoring/health-checker');
      if (healthChecker.instance && healthChecker.instance.cleanupHistory) {
        healthChecker.instance.cleanupHistory();
        results.cleaned.healthHistory = 'Cleaned old entries';
      }
    } catch (e) { results.cleaned.healthHistory = 'Skipped: ' + e.message; }
    
    // Clean container stats
    try {
      const resourceMonitor = require('../managers/resource-monitor');
      if (resourceMonitor.instance && resourceMonitor.instance.cleanupOldStats) {
        resourceMonitor.instance.cleanupOldStats();
        results.cleaned.containerStats = 'Cleaned old entries';
      }
    } catch (e) { results.cleaned.containerStats = 'Skipped: ' + e.message; }
    
    res.json({ success: true, results });
  } catch (e) {
    res.status(500).json({ success: false, error: e.message });
  }
});

module.exports = router;