import Database from 'better-sqlite3';

const SCHEMA = `
CREATE TABLE IF NOT EXISTS users (
  id INTEGER PRIMARY KEY,
  token_hash TEXT UNIQUE NOT NULL,
  display_name TEXT NOT NULL,
  created_at TEXT DEFAULT current_timestamp
);

CREATE TABLE IF NOT EXISTS trips (
  id INTEGER PRIMARY KEY,
  name TEXT NOT NULL,
  start_date TEXT NOT NULL,
  end_date TEXT NOT NULL,
  owner_id INTEGER NOT NULL REFERENCES users(id),
  currency TEXT NOT NULL DEFAULT 'USD',
  join_code TEXT UNIQUE NOT NULL,
  created_at TEXT DEFAULT current_timestamp
);

CREATE TABLE IF NOT EXISTS trip_members (
  trip_id INTEGER NOT NULL REFERENCES trips(id),
  user_id INTEGER NOT NULL REFERENCES users(id),
  role TEXT NOT NULL DEFAULT 'editor',
  sort_order INTEGER NOT NULL DEFAULT 0,
  PRIMARY KEY (trip_id, user_id)
);

CREATE TABLE IF NOT EXISTS entries (
  id INTEGER PRIMARY KEY,
  trip_id INTEGER NOT NULL REFERENCES trips(id),
  date TEXT NOT NULL,
  end_date TEXT,
  type TEXT NOT NULL,
  title TEXT NOT NULL,
  details TEXT DEFAULT '',
  start_time TEXT,
  end_time TEXT,
  location_name TEXT,
  lat REAL,
  lng REAL,
  sort_order INTEGER NOT NULL DEFAULT 0,
  price REAL,
  paid_by INTEGER REFERENCES users(id),
  split_mode TEXT NOT NULL DEFAULT 'equal',
  segments TEXT,
  rental TEXT,
  transport_mode TEXT,
  created_at TEXT DEFAULT current_timestamp
);

CREATE TABLE IF NOT EXISTS entry_participants (
  entry_id INTEGER NOT NULL REFERENCES entries(id),
  user_id INTEGER NOT NULL REFERENCES users(id),
  PRIMARY KEY (entry_id, user_id)
);

CREATE INDEX IF NOT EXISTS idx_entries_trip ON entries(trip_id, date, sort_order, id);
CREATE INDEX IF NOT EXISTS idx_members_user ON trip_members(user_id);
CREATE INDEX IF NOT EXISTS idx_participants_entry ON entry_participants(entry_id);
`;

// Columns added after the initial release: CREATE TABLE IF NOT EXISTS never
// alters existing tables, so databases created by an older version need them
// backfilled with ALTER TABLE.
const MIGRATIONS = [
  { table: 'trips', column: 'currency', ddl: "ALTER TABLE trips ADD COLUMN currency TEXT NOT NULL DEFAULT 'USD'" },
  { table: 'entries', column: 'price', ddl: 'ALTER TABLE entries ADD COLUMN price REAL' },
  { table: 'entries', column: 'paid_by', ddl: 'ALTER TABLE entries ADD COLUMN paid_by INTEGER REFERENCES users(id)' },
  { table: 'entries', column: 'split_mode', ddl: "ALTER TABLE entries ADD COLUMN split_mode TEXT NOT NULL DEFAULT 'equal'" },
  { table: 'entries', column: 'segments', ddl: 'ALTER TABLE entries ADD COLUMN segments TEXT' },
  { table: 'entries', column: 'rental', ddl: 'ALTER TABLE entries ADD COLUMN rental TEXT' },
  { table: 'entries', column: 'end_date', ddl: 'ALTER TABLE entries ADD COLUMN end_date TEXT' },
  { table: 'entries', column: 'transport_mode', ddl: 'ALTER TABLE entries ADD COLUMN transport_mode TEXT' },
  { table: 'trip_members', column: 'sort_order', ddl: 'ALTER TABLE trip_members ADD COLUMN sort_order INTEGER NOT NULL DEFAULT 0' },
];

function applyMigrations(db) {
  for (const { table, column, ddl } of MIGRATIONS) {
    const columns = db.prepare(`PRAGMA table_info(${table})`).all();
    if (!columns.some((c) => c.name === column)) db.exec(ddl);
  }
}

// Data migrations for the 2026-07 entry-type rework (hotel/travel/immigration
// removed in favour of stay/transport/activity). Naturally idempotent: after
// the first run no rows of the legacy types remain, so re-running is a no-op.
export function applyDataMigrations(db) {
  db.exec("UPDATE entries SET type = 'stay' WHERE type = 'hotel'");
  db.exec("UPDATE entries SET type = 'transport' WHERE type = 'travel'");
  db.exec("UPDATE entries SET type = 'activity', title = '🛂 ' || title WHERE type = 'immigration'");
}

// Open (or create) the SQLite database at dbPath and ensure the schema exists.
export function openDb(dbPath) {
  const db = new Database(dbPath);
  db.pragma('journal_mode = WAL');
  db.pragma('foreign_keys = ON');
  db.exec(SCHEMA);
  applyMigrations(db);
  applyDataMigrations(db);
  return db;
}