memer/backend/src/db.ts

import Database from 'better-sqlite3';
import path from 'path';
import fs from 'fs';

const DATA_DIR = process.env.DATA_DIR ?? '/data';
const DB_DIR = path.join(DATA_DIR, 'db');
const DB_PATH = path.join(DB_DIR, 'memer.db');

fs.mkdirSync(DB_DIR, { recursive: true });

const db = new Database(DB_PATH);

db.pragma('journal_mode = WAL');
db.pragma('foreign_keys = ON');

// Core tables
db.exec(`
  CREATE TABLE IF NOT EXISTS collections (
    id         INTEGER PRIMARY KEY AUTOINCREMENT,
    name       TEXT UNIQUE NOT NULL,
    is_default INTEGER NOT NULL DEFAULT 0,
    created_at TEXT NOT NULL DEFAULT (datetime('now'))
  );

  CREATE TABLE IF NOT EXISTS memes (
    id            TEXT PRIMARY KEY,
    title         TEXT NOT NULL,
    description   TEXT,
    file_path     TEXT NOT NULL,
    file_name     TEXT NOT NULL,
    file_size     INTEGER NOT NULL,
    mime_type     TEXT NOT NULL,
    width         INTEGER NOT NULL,
    height        INTEGER NOT NULL,
    parent_id     TEXT REFERENCES memes(id) ON DELETE CASCADE,
    collection_id INTEGER REFERENCES collections(id) ON DELETE SET NULL,
    created_at    TEXT NOT NULL DEFAULT (datetime('now'))
  );

  CREATE TABLE IF NOT EXISTS tags (
    id   INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT UNIQUE NOT NULL COLLATE NOCASE
  );

  CREATE TABLE IF NOT EXISTS meme_tags (
    meme_id TEXT NOT NULL REFERENCES memes(id) ON DELETE CASCADE,
    tag_id  INTEGER NOT NULL REFERENCES tags(id) ON DELETE CASCADE,
    PRIMARY KEY (meme_id, tag_id)
  );

  CREATE INDEX IF NOT EXISTS idx_memes_parent_id ON memes(parent_id);
  CREATE INDEX IF NOT EXISTS idx_memes_created_at ON memes(created_at DESC);
  CREATE INDEX IF NOT EXISTS idx_meme_tags_meme_id ON meme_tags(meme_id);
  CREATE INDEX IF NOT EXISTS idx_meme_tags_tag_id ON meme_tags(tag_id);
`);

// Migration: add collection_id column if upgrading from earlier schema
// Must run BEFORE creating the index on that column
const memesCols = db.prepare('PRAGMA table_info(memes)').all() as { name: string }[];
if (!memesCols.find((c) => c.name === 'collection_id')) {
  db.exec('ALTER TABLE memes ADD COLUMN collection_id INTEGER REFERENCES collections(id) ON DELETE SET NULL');
}

// Create index after the column is guaranteed to exist (handles both fresh and migrated DBs)
db.exec('CREATE INDEX IF NOT EXISTS idx_memes_collection_id ON memes(collection_id)');

// Seed the default UNSORTED collection
const defaultCollection = db
  .prepare('SELECT id FROM collections WHERE is_default = 1')
  .get() as { id: number } | undefined;

if (!defaultCollection) {
  db.prepare("INSERT INTO collections (name, is_default) VALUES ('Unsorted', 1)").run();
}

const unsorted = db
  .prepare('SELECT id FROM collections WHERE is_default = 1')
  .get() as { id: number };

// Assign any existing memes with no collection to UNSORTED
db.prepare('UPDATE memes SET collection_id = ? WHERE collection_id IS NULL').run(unsorted.id);

export const UNSORTED_ID = unsorted.id;

export default db;