// SQLite persistence for games (one row per game id; the full GameState as JSON).
import { mkdirSync } from 'node:fs';
import path from 'node:path';
import Database from 'better-sqlite3';
import type { GameState } from '../shared/types';

export interface Db {
  save(state: GameState): void;
  load(id: string): GameState | null;
  listIds(): string[];
  delete(id: string): boolean;
  close(): void;
}

export function openDb(filePath: string): Db {
  const dir = path.dirname(filePath);
  if (dir) mkdirSync(dir, { recursive: true });
  const db = new Database(filePath);
  db.pragma('journal_mode = WAL');
  db.exec(
    `CREATE TABLE IF NOT EXISTS games (
       id TEXT PRIMARY KEY,
       data TEXT NOT NULL,
       updated_at TEXT NOT NULL
     )`,
  );
  const upsert = db.prepare(
    `INSERT INTO games (id, data, updated_at) VALUES (?, ?, ?)
     ON CONFLICT(id) DO UPDATE SET data = excluded.data, updated_at = excluded.updated_at`,
  );
  const byId = db.prepare('SELECT data FROM games WHERE id = ?');
  const all = db.prepare('SELECT id FROM games ORDER BY updated_at DESC');
  const del = db.prepare('DELETE FROM games WHERE id = ?');
  return {
    save(state) {
      upsert.run(state.id, JSON.stringify(state), new Date().toISOString());
    },
    load(id) {
      const row = byId.get(id) as { data: string } | undefined;
      if (!row) return null;
      try {
        const state = JSON.parse(row.data) as GameState;
        // (v0.22, #16 P3) Rows saved before `GameState.unowned` existed load
        // with it defaulted: a legacy game has no no-man's-land regions.
        if (state.unowned === undefined) state.unowned = [];
        // (v0.23, #16 P4a) Same for pending nation-op proposals: a legacy game
        // has none awaiting confirm/reject.
        if (state.pendingNationOps === undefined) state.pendingNationOps = [];
        return state;
      } catch {
        return null;
      }
    },
    listIds() {
      return (all.all() as { id: string }[]).map((r) => r.id);
    },
    delete(id) {
      return del.run(id).changes > 0;
    },
    close() {
      db.close();
    },
  };
}