/**
 * Boot-time deploy step for the server component.
 *
 * Two jobs, both idempotent:
 *
 *   1. Apply pending SQL migrations from `migrations/` so the database schema
 *      is up-to-date before the HTTP server starts taking traffic. Migration
 *      failure is FATAL — we'd rather crash than serve traffic against a
 *      half-migrated database.
 *   2. Tell the sync service which tables to replicate to clients. We do this
 *      from inside the app — not from a deploy pipeline — so a new table
 *      becomes syncable the moment its migration lands. There's no separate
 *      "sync config" file to keep in sync with the schema. Sync rules push
 *      failure is NON-FATAL: the app still boots and serves HTTP, sync just
 *      doesn't pick up schema changes from this boot. The platform retries.
 *
 * The whole function is safe to re-run on every process start. Migrations
 * track their own state in `migrations.applied` (created by 001_init); the
 * sync rules deploy replaces the existing rule set atomically.
 */

import postgres from 'postgres';
import { readdirSync, existsSync } from 'fs';
import { join } from 'path';

export async function deploy() {
  // Use the direct (non-pooled) connection string. Migrations may run DDL
  // that PgBouncer's transaction pooling can't handle, and the connection is
  // closed immediately afterwards so we don't need pooling here anyway.
  const sql = postgres(process.env.DIRECT_DATABASE_URL!);

  // ─── 1. Migrations ───────────────────────────────────────────────────────
  // Convention: numbered `.sql` files in `migrations/`, sorted lexically.
  // Each file is one transaction. To add a migration: create
  // `migrations/002_<description>.sql` and ship — it will run on next boot.
  const migrationsDir = join(import.meta.dir, 'migrations');
  if (existsSync(migrationsDir)) {
    const files = readdirSync(migrationsDir).filter(f => f.endsWith('.sql')).sort();
    for (const file of files) {
      const content = await Bun.file(join(migrationsDir, file)).text();
      await sql.unsafe(content);
      console.log(`[deploy] Applied migration: ${file}`);
    }
  }

  // ─── 2. Sync rules ───────────────────────────────────────────────────────
  // Introspect every base table in the `public` schema. The sync service is
  // told to replicate all of them to every authenticated client.
  //
  // If you need fine-grained access control (e.g. each user only sees their
  // own rows), replace the wildcard `SELECT *` below with a query that
  // references `auth.user_id()` — the sync service evaluates that function
  // per-connection using the JWT's `sub` claim. Example:
  //
  //   SELECT * FROM notes WHERE owner_id = auth.user_id()
  const tables = await sql`
    SELECT table_name FROM information_schema.tables
    WHERE table_schema = 'public' AND table_type = 'BASE TABLE'
      AND table_name NOT IN ('powersync', 'pg_stat_statements')
  `;

  if (tables.length === 0) {
    console.log('[deploy] No tables found — skipping sync streams');
    await sql.end();
    return;
  }

  // Sync rules are written in YAML and posted to the sync service's admin
  // API. "edition: 3" is the current rules format. The `auto_subscribe: true`
  // flag means clients receive these tables without having to explicitly
  // subscribe — appropriate for a small app with a single rule group.
  const queries = tables.map(t => `      - SELECT * FROM ${t.table_name}`).join('\n');
  const streamsYaml = `config:\n  edition: 3\nstreams:\n  app_data:\n    auto_subscribe: true\n    queries:\n${queries}`;

  // NON-FATAL: if the sync service is unreachable (DNS, network, dead Fly
  // app, etc.) the app still boots and serves HTTP. Sync just won't pick up
  // schema changes from this particular boot. Holding the entire app hostage
  // on a sync push failure means a single dead PowerSync instance makes the
  // whole product look broken — UI shell included.
  try {
    const res = await fetch(`${process.env.APP_SYNC_URL}/api/sync-rules/v1/deploy`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/yaml',
        // The admin token is a shared secret between this app and its sync
        // service — different from the per-client JWTs minted in routes.ts.
        'Authorization': `Bearer ${process.env.APP_SYNC_API_TOKEN}`,
      },
      body: streamsYaml,
      signal: AbortSignal.timeout(10_000),
    });

    if (!res.ok) {
      const body = await res.text();
      console.warn(`[deploy] Sync streams deploy failed (HTTP ${res.status}): ${body}. Continuing without re-deploying sync rules.`);
    } else {
      console.log('[deploy] Sync streams deployed successfully');
    }
  } catch (err) {
    const message = err instanceof Error ? err.message : String(err);
    console.warn(`[deploy] Sync streams deploy failed: ${message}. Continuing without re-deploying sync rules.`);
  }

  await sql.end();
}