import { randomBytes } from 'node:crypto';
import { existsSync, readFileSync, unlinkSync, writeFileSync } from 'node:fs';
import { join } from 'node:path';
import { homedir, tmpdir } from 'node:os';
import { createInterface } from 'node:readline';
import type { GatewayMeta } from './daemon.js';
import { promptMaskedConfirmed } from '../../prompter/masked-prompt.js';
import {
  ENV_FILE,
  GATEWAY_HOME,
  LOG_FILE,
  ensureDirs,
  getDaemonPid,
  installGatewayPackage,
  readMeta,
  resolveGatewayEntry,
  startDaemon,
  stopDaemon,
  waitForHealth,
  writeMeta,
  getInstalledGatewayVersion,
} from './daemon.js';

const MOSAIC_CONFIG_FILE = join(GATEWAY_HOME, 'mosaic.config.json');

// ─── Wizard session state (transient, CU-07-02) ──────────────────────────────

const INSTALL_STATE_FILE = join(
  process.env['XDG_RUNTIME_DIR'] ?? process.env['TMPDIR'] ?? tmpdir(),
  'mosaic-install-state.json',
);

interface InstallSessionState {
  wizardCompletedAt: string;
  mosaicHome: string;
}

function readInstallState(): InstallSessionState | null {
  if (!existsSync(INSTALL_STATE_FILE)) return null;
  try {
    const raw = JSON.parse(readFileSync(INSTALL_STATE_FILE, 'utf-8')) as InstallSessionState;
    // Only trust state that is < 10 minutes old
    const age = Date.now() - new Date(raw.wizardCompletedAt).getTime();
    if (age > 10 * 60 * 1000) return null;
    return raw;
  } catch {
    return null;
  }
}

function clearInstallState(): void {
  try {
    unlinkSync(INSTALL_STATE_FILE);
  } catch {
    // Ignore — file may already be gone
  }
}

interface InstallOpts {
  host: string;
  port: number;
  skipInstall?: boolean;
}

function prompt(rl: ReturnType<typeof createInterface>, question: string): Promise<string> {
  return new Promise((resolve) => rl.question(question, resolve));
}

/**
 * Returns true when the process should skip interactive prompts.
 * Headless mode is activated by `MOSAIC_ASSUME_YES=1` or when stdin is not a
 * TTY (piped/redirected — typical in CI and Docker).
 */
function isHeadless(): boolean {
  return process.env['MOSAIC_ASSUME_YES'] === '1' || !process.stdin.isTTY;
}

export async function runInstall(opts: InstallOpts): Promise<void> {
  const rl = createInterface({ input: process.stdin, output: process.stdout });
  try {
    await doInstall(rl, opts);
  } finally {
    rl.close();
  }
}

async function doInstall(rl: ReturnType<typeof createInterface>, opts: InstallOpts): Promise<void> {
  // CU-07-02: Check for a fresh wizard session state and apply it.
  const sessionState = readInstallState();
  if (sessionState) {
    const defaultHome = join(homedir(), '.config', 'mosaic');
    const customHome = sessionState.mosaicHome !== defaultHome ? sessionState.mosaicHome : null;

    if (customHome && !process.env['MOSAIC_GATEWAY_HOME']) {
      // The wizard ran with a custom MOSAIC_HOME that differs from the default.
      // GATEWAY_HOME is derived from MOSAIC_GATEWAY_HOME (or defaults to
      // ~/.config/mosaic/gateway). Set the env var so the rest of this install
      // inherits the correct location. This must be set before GATEWAY_HOME is
      // evaluated by any imported helper — helpers that re-evaluate the path at
      // call time will pick it up automatically.
      process.env['MOSAIC_GATEWAY_HOME'] = join(customHome, 'gateway');
      console.log(
        `Resuming from wizard session — gateway home set to ${process.env['MOSAIC_GATEWAY_HOME']}\n`,
      );
    } else {
      console.log(
        `Resuming from wizard session — using ${sessionState.mosaicHome} from earlier.\n`,
      );
    }
  }

  const existing = readMeta();
  const envExists = existsSync(ENV_FILE);
  const mosaicConfigExists = existsSync(MOSAIC_CONFIG_FILE);
  let hasConfig = envExists && mosaicConfigExists;
  let daemonRunning = getDaemonPid() !== null;
  const hasAdminToken = Boolean(existing?.adminToken);
  // `opts.host` already incorporates meta fallback via the parent command
  // in gateway.ts (resolveOpts). Using it directly also lets a user pass
  // `--host X` to recover from a previous install that stored a broken
  // host. We intentionally do not prefer `existing.host` over `opts.host`.
  const host = opts.host;

  // Corrupt partial state: exactly one of the two config files survived.
  // This happens when an earlier install was interrupted between writing
  // .env and mosaic.config.json. Rewriting the missing one would silently
  // rotate BETTER_AUTH_SECRET or clobber saved DB/Valkey URLs. Refuse to
  // guess — tell the user how to recover. Check file presence only; do
  // NOT gate on `existing`, because the installer writes config before
  // meta, so an interrupted first install has no meta yet.
  if ((envExists || mosaicConfigExists) && !hasConfig) {
    console.error('Gateway install is in a corrupt partial state:');
    console.error(`  .env file:            ${envExists ? 'present' : 'MISSING'} (${ENV_FILE})`);
    console.error(
      `  mosaic.config.json:   ${mosaicConfigExists ? 'present' : 'MISSING'} (${MOSAIC_CONFIG_FILE})`,
    );
    console.error('\nRun `mosaic gateway uninstall` to clean up, then re-run install.');
    return;
  }

  // Fully set up already — offer to re-run the config wizard and restart.
  // The wizard allows changing storage tier / DB URLs, so this can move
  // the install onto a different data store. We do NOT wipe persisted
  // local data here — for a true scratch wipe run `mosaic gateway
  // uninstall` first.
  let explicitReinstall = false;
  if (existing && hasConfig && daemonRunning && hasAdminToken) {
    console.log(`Gateway is already installed and running (v${existing.version}).`);
    console.log(`  Endpoint:  http://${existing.host}:${existing.port.toString()}`);
    console.log(`  Status:    mosaic gateway status`);
    console.log();
    console.log('Re-running the config wizard will:');
    console.log('  - regenerate .env and mosaic.config.json');
    console.log('  - restart the daemon');
    console.log('  - preserve BETTER_AUTH_SECRET (sessions stay valid)');
    console.log('  - clear the stored admin token (you will re-bootstrap an admin user)');
    console.log('  - allow changing storage tier / DB URLs (may point at a different data store)');
    console.log('To wipe persisted data, run `mosaic gateway uninstall` first.');
    const answer = await prompt(rl, 'Re-run config wizard? [y/N] ');
    if (answer.trim().toLowerCase() !== 'y') {
      console.log('Nothing to do.');
      return;
    }
    // Fall through. The daemon stop below triggers because hasConfig=false
    // forces the wizard to re-run.
    hasConfig = false;
    explicitReinstall = true;
  } else if (existing && (hasConfig || daemonRunning)) {
    // Partial install detected — resume instead of re-prompting the user.
    console.log('Detected a partial gateway installation — resuming setup.\n');
  }

  // If we are going to (re)write config, the running daemon would end up
  // serving the old config while health checks and meta point at the new
  // one. Always stop the daemon before writing config.
  if (!hasConfig && daemonRunning) {
    console.log('Stopping gateway daemon before writing new config...');
    try {
      await stopDaemon();
    } catch (err) {
      const msg = err instanceof Error ? err.message : String(err);
      if (/not running/i.test(msg)) {
        // Raced with daemon exit — fine, proceed.
      } else {
        console.error(`Failed to stop running daemon: ${msg}`);
        console.error('Refusing to rewrite config while an unknown-state daemon is running.');
        console.error('Stop it manually (mosaic gateway stop) and re-run install.');
        return;
      }
    }
    // Re-check — stop may have succeeded but we want to be sure before
    // writing new config files and starting a fresh process.
    if (getDaemonPid() !== null) {
      console.error('Gateway daemon is still running after stop attempt. Aborting.');
      return;
    }
    daemonRunning = false;
  }

  // Step 1: Install npm package. Always run on first install and on any
  // resume where the daemon is NOT already running — a prior failure may
  // have been caused by a broken package version, and the retry should
  // pick up the latest release. Skip only when resuming while the daemon
  // is already alive (package must be working to have started).
  if (!opts.skipInstall && !daemonRunning) {
    installGatewayPackage();
  }

  ensureDirs();

  // Step 2: Collect configuration (skip if both files already exist).
  // On resume, treat the .env file as authoritative for port — but let a
  // user-supplied non-default `--port` override it so they can recover
  // from a conflicting saved port the same way `--host` lets them
  // recover from a bad saved host. `opts.port === 14242` is commander's
  // default (not explicit user input), so we prefer .env in that case.
  let port: number;
  const regeneratedConfig = !hasConfig;
  if (hasConfig) {
    const envPort = readPortFromEnv();
    port = opts.port !== 14242 ? opts.port : (envPort ?? existing?.port ?? opts.port);
    console.log(`Using existing config at ${ENV_FILE} (port ${port.toString()})`);
  } else {
    port = await runConfigWizard(rl, opts);
  }

  // Step 3: Write meta.json. Prefer host from existing meta when resuming.
  let entryPoint: string;
  try {
    entryPoint = resolveGatewayEntry();
  } catch {
    console.error('Error: Gateway package not found after install.');
    console.error('Check that @mosaicstack/gateway installed correctly.');
    return;
  }

  const version = getInstalledGatewayVersion() ?? 'unknown';
  // Preserve the admin token only on a pure resume (no config regeneration).
  // Any time we regenerated config, the wizard may have pointed at a
  // different storage tier / DB URL, so the old token is unverifiable —
  // drop it and require re-bootstrap.
  const preserveToken = !regeneratedConfig && Boolean(existing?.adminToken);
  const meta: GatewayMeta = {
    version,
    installedAt: explicitReinstall
      ? new Date().toISOString()
      : (existing?.installedAt ?? new Date().toISOString()),
    entryPoint,
    host,
    port,
    ...(preserveToken && existing?.adminToken ? { adminToken: existing.adminToken } : {}),
  };
  writeMeta(meta);

  // Step 4: Start the daemon (idempotent — skip if already running).
  if (!daemonRunning) {
    console.log('\nStarting gateway daemon...');
    try {
      const pid = startDaemon();
      console.log(`Gateway started (PID ${pid.toString()})`);
    } catch (err) {
      console.error(`Failed to start: ${err instanceof Error ? err.message : String(err)}`);
      printLogTail();
      return;
    }
  } else {
    console.log('\nGateway daemon is already running.');
  }

  // Step 5: Wait for health
  console.log('Waiting for gateway to become healthy...');
  const healthy = await waitForHealth(host, port, 30_000);
  if (!healthy) {
    console.error('\nGateway did not become healthy within 30 seconds.');
    printLogTail();
    console.error('\nFix the underlying error above, then re-run `mosaic gateway install`.');
    return;
  }
  console.log('Gateway is healthy.\n');

  // Step 6: Bootstrap — first admin user.
  await bootstrapFirstUser(rl, host, port, meta);

  console.log('\n─── Installation Complete ───');
  console.log(`  Endpoint:  http://${host}:${port.toString()}`);
  console.log(`  Config:    ${GATEWAY_HOME}`);
  console.log(`  Logs:      mosaic gateway logs`);
  console.log(`  Status:    mosaic gateway status`);

  // Step 7: Post-install verification (CU-07-03)
  const { runPostInstallVerification } = await import('./verify.js');
  await runPostInstallVerification(host, port);

  // CU-07-02: Clear transient wizard session state on successful install.
  clearInstallState();
}

async function runConfigWizard(
  rl: ReturnType<typeof createInterface>,
  opts: InstallOpts,
): Promise<number> {
  console.log('\n─── Gateway Configuration ───\n');

  // If a previous .env exists on disk, reuse its BETTER_AUTH_SECRET so
  // regenerating config does not silently log out existing users.
  const preservedAuthSecret = readEnvVarFromFile('BETTER_AUTH_SECRET');
  if (preservedAuthSecret) {
    console.log('(Preserving existing BETTER_AUTH_SECRET — auth sessions will remain valid.)\n');
  }

  let tier: 'local' | 'team';
  let port: number;
  let databaseUrl: string | undefined;
  let valkeyUrl: string | undefined;
  let anthropicKey: string;
  let corsOrigin: string;

  if (isHeadless()) {
    // ── Headless / non-interactive path ────────────────────────────────────
    console.log('Headless mode detected — reading configuration from environment variables.\n');

    const storageTierEnv = process.env['MOSAIC_STORAGE_TIER'] ?? 'local';
    tier = storageTierEnv === 'team' ? 'team' : 'local';

    const portEnv = process.env['MOSAIC_GATEWAY_PORT'];
    port = portEnv ? parseInt(portEnv, 10) : opts.port;

    databaseUrl = process.env['MOSAIC_DATABASE_URL'];
    valkeyUrl = process.env['MOSAIC_VALKEY_URL'];
    anthropicKey = process.env['MOSAIC_ANTHROPIC_API_KEY'] ?? '';
    corsOrigin = process.env['MOSAIC_CORS_ORIGIN'] ?? 'http://localhost:3000';

    // Validate required vars for team tier
    if (tier === 'team') {
      const missing: string[] = [];
      if (!databaseUrl) missing.push('MOSAIC_DATABASE_URL');
      if (!valkeyUrl) missing.push('MOSAIC_VALKEY_URL');
      if (missing.length > 0) {
        console.error(
          `Error: headless install with tier=team requires the following env vars:\n` +
            missing.map((v) => `  ${v}`).join('\n'),
        );
        process.exit(1);
      }
    }

    console.log(`  Storage tier:  ${tier}`);
    console.log(`  Gateway port:  ${port.toString()}`);
    if (tier === 'team') {
      console.log(`  DATABASE_URL:  ${databaseUrl ?? ''}`);
      console.log(`  VALKEY_URL:    ${valkeyUrl ?? ''}`);
    }
    console.log(`  CORS origin:   ${corsOrigin}`);
    console.log();
  } else {
    // ── Interactive path ────────────────────────────────────────────────────
    console.log('Storage tier:');
    console.log('  1. Local (embedded database, no dependencies)');
    console.log('  2. Team (PostgreSQL + Valkey required)');
    const tierAnswer = (await prompt(rl, 'Select [1]: ')).trim() || '1';
    tier = tierAnswer === '2' ? 'team' : 'local';

    port =
      opts.port !== 14242
        ? opts.port
        : parseInt(
            (await prompt(rl, `Gateway port [${opts.port.toString()}]: `)) || opts.port.toString(),
            10,
          );

    if (tier === 'team') {
      databaseUrl =
        (await prompt(rl, 'DATABASE_URL [postgresql://mosaic:mosaic@localhost:5433/mosaic]: ')) ||
        'postgresql://mosaic:mosaic@localhost:5433/mosaic';

      valkeyUrl =
        (await prompt(rl, 'VALKEY_URL [redis://localhost:6380]: ')) || 'redis://localhost:6380';
    }

    anthropicKey = await prompt(rl, 'ANTHROPIC_API_KEY (optional, press Enter to skip): ');

    corsOrigin =
      (await prompt(rl, 'CORS origin [http://localhost:3000]: ')) || 'http://localhost:3000';
  }

  const authSecret = preservedAuthSecret ?? randomBytes(32).toString('hex');

  const envLines = [
    `GATEWAY_PORT=${port.toString()}`,
    `BETTER_AUTH_SECRET=${authSecret}`,
    `BETTER_AUTH_URL=http://${opts.host}:${port.toString()}`,
    `GATEWAY_CORS_ORIGIN=${corsOrigin}`,
    `OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318`,
    `OTEL_SERVICE_NAME=mosaic-gateway`,
  ];

  if (tier === 'team' && databaseUrl && valkeyUrl) {
    envLines.push(`DATABASE_URL=${databaseUrl}`);
    envLines.push(`VALKEY_URL=${valkeyUrl}`);
  }

  if (anthropicKey) {
    envLines.push(`ANTHROPIC_API_KEY=${anthropicKey}`);
  }

  writeFileSync(ENV_FILE, envLines.join('\n') + '\n', { mode: 0o600 });
  console.log(`\nConfig written to ${ENV_FILE}`);

  const mosaicConfig =
    tier === 'local'
      ? {
          tier: 'local',
          storage: { type: 'pglite', dataDir: join(GATEWAY_HOME, 'storage-pglite') },
          queue: { type: 'local', dataDir: join(GATEWAY_HOME, 'queue') },
          memory: { type: 'keyword' },
        }
      : {
          tier: 'team',
          storage: { type: 'postgres', url: databaseUrl },
          queue: { type: 'bullmq', url: valkeyUrl },
          memory: { type: 'pgvector' },
        };

  writeFileSync(MOSAIC_CONFIG_FILE, JSON.stringify(mosaicConfig, null, 2) + '\n', { mode: 0o600 });
  console.log(`Config written to ${MOSAIC_CONFIG_FILE}`);

  return port;
}

function readEnvVarFromFile(key: string): string | null {
  if (!existsSync(ENV_FILE)) return null;
  try {
    for (const line of readFileSync(ENV_FILE, 'utf-8').split('\n')) {
      const trimmed = line.trim();
      if (!trimmed || trimmed.startsWith('#')) continue;
      const eqIdx = trimmed.indexOf('=');
      if (eqIdx <= 0) continue;
      if (trimmed.slice(0, eqIdx) !== key) continue;
      return trimmed.slice(eqIdx + 1);
    }
  } catch {
    return null;
  }
  return null;
}

function readPortFromEnv(): number | null {
  const raw = readEnvVarFromFile('GATEWAY_PORT');
  if (raw === null) return null;
  const parsed = parseInt(raw, 10);
  return Number.isNaN(parsed) ? null : parsed;
}

function printLogTail(maxLines = 30): void {
  if (!existsSync(LOG_FILE)) {
    console.error(`(no log file at ${LOG_FILE})`);
    return;
  }
  try {
    const lines = readFileSync(LOG_FILE, 'utf-8')
      .split('\n')
      .filter((l) => l.trim().length > 0);
    const tail = lines.slice(-maxLines);
    if (tail.length === 0) {
      console.error('(log file is empty)');
      return;
    }
    console.error(`\n─── Last ${tail.length.toString()} log lines (${LOG_FILE}) ───`);
    for (const line of tail) console.error(line);
    console.error('─────────────────────────────────────────────');
  } catch (err) {
    console.error(`Could not read log file: ${err instanceof Error ? err.message : String(err)}`);
  }
}

function printAdminTokenBanner(token: string): void {
  const border = '═'.repeat(68);
  console.log();
  console.log(border);
  console.log('  Admin API Token');
  console.log(border);
  console.log();
  console.log(`    ${token}`);
  console.log();
  console.log('  Save this token now — it will not be shown again in full.');
  console.log('  It is stored (read-only) at:');
  console.log(`    ${join(GATEWAY_HOME, 'meta.json')}`);
  console.log();
  console.log('  Use it with admin endpoints, e.g.:');
  console.log(`    mosaic gateway --token <token> status`);
  console.log(border);
}

async function bootstrapFirstUser(
  rl: ReturnType<typeof createInterface>,
  host: string,
  port: number,
  meta: GatewayMeta,
): Promise<void> {
  const baseUrl = `http://${host}:${port.toString()}`;

  try {
    const statusRes = await fetch(`${baseUrl}/api/bootstrap/status`);
    if (!statusRes.ok) return;

    const status = (await statusRes.json()) as { needsSetup: boolean };
    if (!status.needsSetup) {
      if (meta.adminToken) {
        console.log('Admin user already exists (token on file).');
        return;
      }

      // Admin user exists but no token — offer inline recovery when interactive.
      console.log('Admin user already exists but no admin token is on file.');

      if (process.stdin.isTTY) {
        const answer = (await prompt(rl, 'Run token recovery now? [Y/n] ')).trim().toLowerCase();
        if (answer === '' || answer === 'y' || answer === 'yes') {
          console.log();
          try {
            const { ensureSession, mintAdminToken, persistToken } = await import('./token-ops.js');
            const cookie = await ensureSession(baseUrl);
            const label = `CLI recovery token (${new Date().toISOString().slice(0, 16).replace('T', ' ')})`;
            const minted = await mintAdminToken(baseUrl, cookie, label);
            persistToken(baseUrl, minted);
          } catch (err) {
            console.error(
              `Token recovery failed: ${err instanceof Error ? err.message : String(err)}`,
            );
          }
          return;
        }
      }

      console.log('No admin token on file. Run: mosaic gateway config recover-token');
      return;
    }
  } catch {
    console.warn('Could not check bootstrap status — skipping first user setup.');
    return;
  }

  console.log('─── Admin User Setup ───\n');

  let name: string;
  let email: string;
  let password: string;

  if (isHeadless()) {
    // ── Headless path ──────────────────────────────────────────────────────
    const nameEnv = process.env['MOSAIC_ADMIN_NAME']?.trim() ?? '';
    const emailEnv = process.env['MOSAIC_ADMIN_EMAIL']?.trim() ?? '';
    const passwordEnv = process.env['MOSAIC_ADMIN_PASSWORD'] ?? '';

    const missing: string[] = [];
    if (!nameEnv) missing.push('MOSAIC_ADMIN_NAME');
    if (!emailEnv) missing.push('MOSAIC_ADMIN_EMAIL');
    if (!passwordEnv) missing.push('MOSAIC_ADMIN_PASSWORD');

    if (missing.length > 0) {
      console.error(
        `Error: headless admin bootstrap requires the following env vars:\n` +
          missing.map((v) => `  ${v}`).join('\n'),
      );
      process.exit(1);
    }

    if (passwordEnv.length < 8) {
      console.error('Error: MOSAIC_ADMIN_PASSWORD must be at least 8 characters.');
      process.exit(1);
    }

    name = nameEnv;
    email = emailEnv;
    password = passwordEnv;
  } else {
    // ── Interactive path ────────────────────────────────────────────────────
    name = (await prompt(rl, 'Admin name: ')).trim();
    if (!name) {
      console.error('Name is required.');
      return;
    }

    email = (await prompt(rl, 'Admin email: ')).trim();
    if (!email) {
      console.error('Email is required.');
      return;
    }

    password = await promptMaskedConfirmed(
      'Admin password (min 8 chars): ',
      'Confirm password:            ',
      (v) => (v.length < 8 ? 'Password must be at least 8 characters' : undefined),
    );
  }

  try {
    const res = await fetch(`${baseUrl}/api/bootstrap/setup`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ name, email, password }),
    });

    if (!res.ok) {
      const body = await res.text().catch(() => '');
      console.error(`Bootstrap failed (${res.status.toString()}): ${body}`);
      return;
    }

    const result = (await res.json()) as {
      user: { id: string; email: string };
      token: { plaintext: string };
    };

    // Persist the token so future CLI calls can authenticate automatically.
    meta.adminToken = result.token.plaintext;
    writeMeta(meta);

    console.log(`\nAdmin user created: ${result.user.email}`);
    printAdminTokenBanner(result.token.plaintext);
  } catch (err) {
    console.error(`Bootstrap error: ${err instanceof Error ? err.message : String(err)}`);
  }
}