import { readdirSync, readFileSync } from 'node:fs';
import { DatabaseSync } from 'node:sqlite';

const MIGRATIONS = new URL('../migrations/', import.meta.url);

// enough of d1 over node's sqlite to run the real migration and queries
export class TestD1 {
  sqlite = new DatabaseSync(':memory:');
  writes = 0;

  // `stopAt` leaves the later migrations out, to test one against older data
  constructor(stopAt?: string) {
    for (const name of readdirSync(MIGRATIONS).sort()) {
      if (name === stopAt) break;
      this.migrate(name);
    }
  }

  migrate(name: string): void {
    this.sqlite.exec(readFileSync(new URL(name, MIGRATIONS), 'utf8'));
  }

  prepare(sql: string): TestStatement {
    return new TestStatement(this, sql, []);
  }

  async batch(statements: TestStatement[]): Promise<unknown[]> {
    this.sqlite.exec('BEGIN');
    try {
      const out = statements.map((statement) => statement.execute());
      this.sqlite.exec('COMMIT');
      return out;
    } catch (err) {
      this.sqlite.exec('ROLLBACK');
      throw err;
    }
  }

  query<T>(sql: string, ...params: unknown[]): T[] {
    return this.sqlite.prepare(sql).all(...params) as T[];
  }

  asD1(): D1Database {
    return this as unknown as D1Database;
  }
}

class TestStatement {
  constructor(
    private db: TestD1,
    private sql: string,
    private params: unknown[],
  ) {}

  bind(...params: unknown[]): TestStatement {
    return new TestStatement(this.db, this.sql, params);
  }

  execute(): { results: Record<string, unknown>[] } {
    const statement = this.db.sqlite.prepare(this.sql);
    if (statement.columns().length > 0) return { results: statement.all(...this.params) };
    this.db.writes += Number(statement.run(...this.params).changes);
    return { results: [] };
  }

  async all(): Promise<{ results: Record<string, unknown>[] }> {
    return this.execute();
  }

  async first(): Promise<Record<string, unknown> | null> {
    return this.execute().results[0] ?? null;
  }

  async run(): Promise<{ results: Record<string, unknown>[] }> {
    return this.execute();
  }
}