#!/usr/bin/env node
// install-kb-cron.mjs — Standalone cross-OS install helper for the weekly
// KB-update cron job. Reads the appropriate template from
// scripts/kb-update/templates/, fills {{NODE_BIN}}, {{PLUGIN_ROOT}},
// {{LOG_FILE}}, {{SCHEDULE_HOUR/MINUTE/DAY_OF_WEEK}} placeholders, writes
// to the platform-specific scheduler dir, and registers the job with the
// host scheduler.
//
//   macOS  → ~/Library/LaunchAgents/com.fromaitochitta.ms-ai-architect.kb-update.plist
//            launchctl bootstrap gui/<uid> <path>   (EIO fallback to load -w)
//   Linux  → ~/.config/systemd/user/{ms-ai-architect-kb-update.service, .timer}
//            systemctl --user daemon-reload && enable --now ms-ai-architect-kb-update.timer
//   Windows → invoke ms-ai-architect-kb-update.ps1 via
//             powershell -ExecutionPolicy Bypass -File <path>
//             (template registers via Register-ScheduledTask itself).
//             Marked beta — not validated against a real Windows machine.
//
// Usage:
//   install-kb-cron.mjs [--print-only] [--target macos|linux|windows]
//                       [--uninstall [--purge]]
//                       [--node-bin <path>] [--claude-bin <path>]
//                       [--schedule "M H * * D"]   default: "23 4 * * 3" (Wed 04:23)
//
// --print-only renders the filled template to stdout and exits without
// touching the filesystem (no scheduler dirs, no log dirs, nothing under
// HOME). Use it for inspection or for cross-target rendering on a
// developer machine.

import { spawnSync } from 'node:child_process';
import {
  readFileSync,
  writeFileSync,
  mkdirSync,
  existsSync,
  unlinkSync,
  rmSync,
} from 'node:fs';
import { homedir, platform as osPlatform } from 'node:os';
import { join, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';

const __dirname = dirname(fileURLToPath(import.meta.url));
const PLUGIN_ROOT = join(__dirname, '..');
const TEMPLATES_DIR = join(__dirname, 'kb-update', 'templates');
const APP = 'ms-ai-architect';
const LAUNCHD_LABEL = 'com.fromaitochitta.ms-ai-architect.kb-update';
const SYSTEMD_UNIT = 'ms-ai-architect-kb-update';
const WIN_TASK_NAME = 'ms-ai-architect-kb-update';

// ---------- CLI parsing ----------

function printUsage() {
  console.log(`Usage: install-kb-cron.mjs [options]

Installs (or removes) the weekly Microsoft Learn KB-update job for the
ms-ai-architect plugin on the host scheduler.

Options:
  --print-only          Print filled template to stdout, no file writes
  --target <os>         Target OS: macos|linux|windows (default: auto-detect)
  --uninstall           Reverse the registration (idempotent)
  --purge               With --uninstall: also delete logs/status/.kb-backup
  --node-bin <path>     Path to node binary (default: process.execPath)
  --claude-bin <path>   Path to claude binary (default: 'claude' on PATH)
  --schedule "M H * * D"  Cron expression (default: "23 4 * * 3" = Wed 04:23)
  --help, -h            Show this message and exit
`);
}

function parseArgs(argv) {
  const args = {
    printOnly: false,
    target: null,
    uninstall: false,
    purge: false,
    nodeBin: null,
    claudeBin: null,
    schedule: '23 4 * * 3',
  };
  for (let i = 0; i < argv.length; i++) {
    const a = argv[i];
    const eq = (name) => a.startsWith(`${name}=`) ? a.slice(name.length + 1) : null;
    if (a === '--print-only') args.printOnly = true;
    else if (a === '--uninstall') args.uninstall = true;
    else if (a === '--purge') args.purge = true;
    else if (a === '--help' || a === '-h') { printUsage(); process.exit(0); }
    else if (a === '--target') args.target = argv[++i];
    else if (eq('--target') !== null) args.target = eq('--target');
    else if (a === '--node-bin') args.nodeBin = argv[++i];
    else if (eq('--node-bin') !== null) args.nodeBin = eq('--node-bin');
    else if (a === '--claude-bin') args.claudeBin = argv[++i];
    else if (eq('--claude-bin') !== null) args.claudeBin = eq('--claude-bin');
    else if (a === '--schedule') args.schedule = argv[++i];
    else if (eq('--schedule') !== null) args.schedule = eq('--schedule');
    else {
      console.error(`Unknown argument: ${a}`);
      console.error('Run with --help to see usage.');
      process.exit(2);
    }
  }
  return args;
}

// ---------- Target detection ----------

function detectHostTarget() {
  switch (process.platform) {
    case 'darwin': return 'macos';
    case 'linux':  return 'linux';
    case 'win32':  return 'windows';
    default:       return null;
  }
}

const VALID_TARGETS = new Set(['macos', 'linux', 'windows']);

// ---------- Schedule parsing ----------

function parseSchedule(expr) {
  if (typeof expr !== 'string') {
    throw new Error(`invalid schedule: not a string`);
  }
  const parts = expr.trim().split(/\s+/);
  if (parts.length !== 5) {
    throw new Error(
      `invalid schedule "${expr}" — expected 5 cron fields "M H * * D"`,
    );
  }
  const [m, h, dom, mon, dow] = parts;
  if (dom !== '*' || mon !== '*') {
    throw new Error(
      `invalid schedule "${expr}" — day-of-month and month must be "*"`,
    );
  }
  const minute = Number(m);
  const hour = Number(h);
  const dayOfWeek = Number(dow);
  if (!Number.isInteger(minute) || minute < 0 || minute > 59) {
    throw new Error(`invalid schedule minute "${m}" (expected 0-59)`);
  }
  if (!Number.isInteger(hour) || hour < 0 || hour > 23) {
    throw new Error(`invalid schedule hour "${h}" (expected 0-23)`);
  }
  if (!Number.isInteger(dayOfWeek) || dayOfWeek < 0 || dayOfWeek > 6) {
    throw new Error(`invalid schedule day-of-week "${dow}" (expected 0-6)`);
  }
  return { minute, hour, dayOfWeek };
}

// ---------- Path resolution (no side effects) ----------

function resolveAppPaths(target) {
  const h = homedir();
  if (target === 'macos') {
    return {
      logFile: join(h, 'Library', 'Logs', APP, 'kb-update.log'),
      logDir:  join(h, 'Library', 'Logs', APP),
      cacheDir: join(h, 'Library', 'Caches', APP),
    };
  }
  if (target === 'windows') {
    const lad = process.env.LOCALAPPDATA || join(h, 'AppData', 'Local');
    return {
      logFile: join(lad, APP, 'Logs', 'kb-update.log'),
      logDir:  join(lad, APP, 'Logs'),
      cacheDir: join(lad, APP, 'Cache'),
    };
  }
  // linux
  const xdgState = process.env.XDG_STATE_HOME || join(h, '.local', 'state');
  const xdgCache = process.env.XDG_CACHE_HOME || join(h, '.cache');
  return {
    logFile: join(xdgState, APP, 'logs', 'kb-update.log'),
    logDir:  join(xdgState, APP, 'logs'),
    cacheDir: join(xdgCache, APP),
  };
}

// ---------- Template substitution ----------

function fillTemplate(content, vars) {
  return content
    .replace(/\{\{NODE_BIN\}\}/g, vars.nodeBin)
    .replace(/\{\{PLUGIN_ROOT\}\}/g, vars.pluginRoot)
    .replace(/\{\{LOG_FILE\}\}/g, vars.logFile)
    .replace(/\{\{SCHEDULE_HOUR\}\}/g, String(vars.hour))
    .replace(/\{\{SCHEDULE_MINUTE\}\}/g, String(vars.minute))
    .replace(/\{\{SCHEDULE_DAY_OF_WEEK\}\}/g, String(vars.dayOfWeek));
}

function readTemplate(name) {
  return readFileSync(join(TEMPLATES_DIR, name), 'utf8');
}

// ---------- MCP / WSL detection ----------

function checkMcpServer() {
  const claudeJson = join(homedir(), '.claude.json');
  if (!existsSync(claudeJson)) return null;
  try {
    const data = JSON.parse(readFileSync(claudeJson, 'utf8'));
    const mcp = data && data.mcpServers ? data.mcpServers : {};
    return Boolean(mcp['microsoft-learn']);
  } catch {
    return null;
  }
}

function isWsl() {
  if (process.platform !== 'linux') return false;
  try {
    const v = readFileSync('/proc/version', 'utf8');
    return /Microsoft|WSL/i.test(v);
  } catch {
    return false;
  }
}

// ---------- Per-target install ----------

function installMacos(args, vars) {
  const filled = fillTemplate(
    readTemplate(`${LAUNCHD_LABEL}.plist`),
    vars,
  );
  if (args.printOnly) {
    process.stdout.write(filled);
    return;
  }
  const dest = join(homedir(), 'Library', 'LaunchAgents', `${LAUNCHD_LABEL}.plist`);
  mkdirSync(dirname(dest), { recursive: true });
  mkdirSync(vars.logDir, { recursive: true });
  writeFileSync(dest, filled, 'utf8');

  // launchctl bootstrap gui/<uid> <path> (with load -w fallback on error).
  if (typeof process.getuid === 'function') {
    const uid = process.getuid();
    const r = spawnSync('launchctl', ['bootstrap', `gui/${uid}`, dest], {
      encoding: 'utf8',
    });
    if (r.status !== 0) {
      console.error(`launchctl bootstrap returned ${r.status}: ${r.stderr.trim()}`);
      console.error('Falling back to: launchctl load -w');
      const r2 = spawnSync('launchctl', ['load', '-w', dest], { encoding: 'utf8' });
      if (r2.status !== 0) {
        throw new Error(`launchctl load -w failed: ${r2.stderr.trim()}`);
      }
    }
  }

  console.log(`✓ Installed ${dest}`);
  console.log('Next steps:');
  console.log(`  - Verify: launchctl list | grep ${LAUNCHD_LABEL}`);
  console.log(`  - Logs:   ${vars.logFile}`);
}

function installLinux(args, vars) {
  const serviceFilled = fillTemplate(readTemplate(`${SYSTEMD_UNIT}.service`), vars);
  const timerFilled   = fillTemplate(readTemplate(`${SYSTEMD_UNIT}.timer`), vars);

  if (args.printOnly) {
    process.stdout.write(`# === ${SYSTEMD_UNIT}.service ===\n`);
    process.stdout.write(serviceFilled);
    process.stdout.write(`\n# === ${SYSTEMD_UNIT}.timer ===\n`);
    process.stdout.write(timerFilled);
    return;
  }

  // Pre-check: is systemd present? (skip if --target linux on non-linux host —
  // user is likely cross-rendering by mistake; refuse to actually install.)
  if (process.platform !== 'linux') {
    throw new Error(
      `cannot install systemd units on host platform "${process.platform}" — ` +
      `use --print-only to render templates for cross-OS inspection`,
    );
  }
  const sys = spawnSync('systemctl', ['is-system-running'], { encoding: 'utf8' });
  if (sys.status === null || sys.error) {
    throw new Error('systemctl not available — systemd is not running on this system');
  }

  if (isWsl()) {
    console.warn('WARNING: detected WSL — systemd --user may need manual setup.');
  }

  const userDir = join(homedir(), '.config', 'systemd', 'user');
  mkdirSync(userDir, { recursive: true });
  mkdirSync(vars.logDir, { recursive: true });
  const servicePath = join(userDir, `${SYSTEMD_UNIT}.service`);
  const timerPath   = join(userDir, `${SYSTEMD_UNIT}.timer`);
  writeFileSync(servicePath, serviceFilled, 'utf8');
  writeFileSync(timerPath, timerFilled, 'utf8');

  spawnSync('systemctl', ['--user', 'daemon-reload'], { stdio: 'inherit' });
  const en = spawnSync(
    'systemctl',
    ['--user', 'enable', '--now', `${SYSTEMD_UNIT}.timer`],
    { stdio: 'inherit' },
  );
  if (en.status !== 0) {
    throw new Error(`systemctl --user enable --now ${SYSTEMD_UNIT}.timer failed`);
  }

  console.log(`✓ Installed ${servicePath}`);
  console.log(`✓ Installed ${timerPath}`);
  console.log('Next steps:');
  console.log(`  - Verify: systemctl --user list-timers | grep ${SYSTEMD_UNIT}`);
  console.log(`  - Optional: sudo loginctl enable-linger $USER (autostart without login)`);
  console.log(`  - Logs:   ${vars.logFile}`);
}

function installWindows(args, vars) {
  const filled = fillTemplate(readTemplate(`${SYSTEMD_UNIT}.ps1`), vars);
  if (args.printOnly) {
    process.stdout.write(filled);
    return;
  }

  if (process.platform !== 'win32') {
    throw new Error(
      `cannot register Windows scheduled task on host platform "${process.platform}" — ` +
      `use --print-only to render the .ps1 for cross-OS inspection`,
    );
  }
  console.warn(
    'NOTE: Windows install path is BETA — not validated against a real Windows machine.',
  );

  // Materialize the .ps1 in the cache dir, then invoke it.
  mkdirSync(vars.cacheDir, { recursive: true });
  mkdirSync(vars.logDir, { recursive: true });
  const ps1Path = join(vars.cacheDir, 'install-kb-cron.ps1');
  writeFileSync(ps1Path, filled, 'utf8');
  const r = spawnSync(
    'powershell',
    ['-ExecutionPolicy', 'Bypass', '-File', ps1Path],
    { stdio: 'inherit' },
  );
  if (r.status !== 0) {
    throw new Error(`powershell install failed (status=${r.status})`);
  }
  console.log(`✓ Registered Windows task '${WIN_TASK_NAME}'`);
  console.log('Next steps:');
  console.log(`  - Verify: schtasks /Query /TN ${WIN_TASK_NAME}`);
  console.log(`  - Logs:   ${vars.logFile}`);
}

// ---------- Per-target uninstall ----------

function uninstallMacos(host) {
  const dest = join(homedir(), 'Library', 'LaunchAgents', `${LAUNCHD_LABEL}.plist`);
  if (!existsSync(dest)) {
    console.log(`(nothing to remove at ${dest})`);
    return;
  }
  if (host === 'macos' && typeof process.getuid === 'function') {
    const uid = process.getuid();
    spawnSync('launchctl', ['bootout', `gui/${uid}`, dest], { encoding: 'utf8' });
    spawnSync('launchctl', ['unload', '-w', dest], { encoding: 'utf8' });
  }
  unlinkSync(dest);
  console.log(`✓ Removed ${dest}`);
}

function uninstallLinux(host) {
  const userDir = join(homedir(), '.config', 'systemd', 'user');
  const servicePath = join(userDir, `${SYSTEMD_UNIT}.service`);
  const timerPath   = join(userDir, `${SYSTEMD_UNIT}.timer`);
  const anyExists = existsSync(servicePath) || existsSync(timerPath);

  if (!anyExists) {
    console.log(`(nothing to remove at ${userDir})`);
    return;
  }
  if (host === 'linux') {
    spawnSync(
      'systemctl',
      ['--user', 'disable', '--now', `${SYSTEMD_UNIT}.timer`],
      { encoding: 'utf8' },
    );
  }
  for (const p of [servicePath, timerPath]) {
    if (existsSync(p)) {
      unlinkSync(p);
      console.log(`✓ Removed ${p}`);
    }
  }
  if (host === 'linux') {
    spawnSync('systemctl', ['--user', 'daemon-reload'], { encoding: 'utf8' });
  }
}

function uninstallWindows(host) {
  if (host === 'windows') {
    const r = spawnSync(
      'schtasks',
      ['/Delete', '/TN', WIN_TASK_NAME, '/F'],
      { encoding: 'utf8' },
    );
    if (r.status === 0) {
      console.log(`✓ Removed Windows task '${WIN_TASK_NAME}'`);
    } else {
      console.log(`(nothing to remove — task '${WIN_TASK_NAME}' not registered)`);
    }
  } else {
    console.log(`(nothing to remove — schtasks unavailable on host '${host}')`);
  }
}

function purgeAppFiles(target) {
  const paths = resolveAppPaths(target);
  const backupDir = join(PLUGIN_ROOT, '.kb-backup');
  let removed = 0;
  for (const d of [paths.logDir, paths.cacheDir, backupDir]) {
    if (existsSync(d)) {
      rmSync(d, { recursive: true, force: true });
      console.log(`✓ Purged ${d}`);
      removed++;
    }
  }
  if (removed === 0) {
    console.log('(nothing to purge)');
  }
}

// ---------- Main ----------

function main() {
  const args = parseArgs(process.argv.slice(2));

  if (!args.target) args.target = detectHostTarget();
  if (!args.target || !VALID_TARGETS.has(args.target)) {
    console.error(
      `unsupported or invalid --target "${args.target}" — must be one of: macos, linux, windows`,
    );
    process.exit(2);
  }

  // Resolve binaries.
  const nodeBin = args.nodeBin || process.execPath;
  // claudeBin is only consumed by the templates that reference it; current
  // template set assumes 'claude' is on PATH inside the cron environment, so
  // the override is currently a no-op pass-through. Accept the flag so future
  // template revisions can pick it up without a CLI break.
  void args.claudeBin;

  // Schedule parsing.
  let sched;
  try {
    sched = parseSchedule(args.schedule);
  } catch (err) {
    console.error(`ERROR: ${err.message}`);
    process.exit(2);
  }

  const paths = resolveAppPaths(args.target);
  const vars = {
    nodeBin,
    pluginRoot: PLUGIN_ROOT,
    logFile: paths.logFile,
    logDir: paths.logDir,
    cacheDir: paths.cacheDir,
    minute: sched.minute,
    hour: sched.hour,
    dayOfWeek: sched.dayOfWeek,
  };

  // Uninstall path.
  if (args.uninstall) {
    const host = detectHostTarget();
    if (args.target === 'macos')   uninstallMacos(host);
    if (args.target === 'linux')   uninstallLinux(host);
    if (args.target === 'windows') uninstallWindows(host);
    if (args.purge) purgeAppFiles(args.target);
    return;
  }

  // MCP soft-warn (install path only).
  if (!args.printOnly) {
    const mcp = checkMcpServer();
    if (mcp === false) {
      console.warn(
        'WARNING: ~/.claude.json has no `microsoft-learn` MCP server entry. ' +
        'KB-updates will run but the agent will lack live Microsoft Learn access.',
      );
    } else if (mcp === null) {
      console.warn('WARNING: could not read ~/.claude.json — skipping MCP server check.');
    }
  }

  if (args.target === 'macos')   installMacos(args, vars);
  if (args.target === 'linux')   installLinux(args, vars);
  if (args.target === 'windows') installWindows(args, vars);
}

try {
  main();
} catch (err) {
  console.error(`ERROR: ${err.message}`);
  process.exit(1);
}