import type Database from 'better-sqlite3';

export function tuneConnection(handle: Database.Database, reader = false): void {
    handle.pragma(`cache_size = -${reader ? 32768 : 131072}`);
    // MEMORY also puts VACUUM's transient database in RAM. Disk-backed temps
    // keep migrations and large sorts from growing with the entire database.
    handle.pragma('temp_store = FILE');
    // mmap is opt-in because the controller data directory can be a network mount.
    const mmapMiB = Number(process.env.EC_SQLITE_MMAP_MB ?? 0);
    if (Number.isSafeInteger(mmapMiB) && mmapMiB >= 0 && mmapMiB <= 32768) {
        handle.pragma(`mmap_size = ${mmapMiB * 1024 * 1024}`);
    }
    if (!reader) handle.pragma('journal_size_limit = 67108864');
}

/** Startup needs two page caches during VACUUM, plus buffers for legacy files. */
export function tuneMigrationConnection(handle: Database.Database): void {
    handle.pragma('cache_size = -16384');
    handle.pragma('temp_store = FILE');
    handle.pragma('mmap_size = 0');
    handle.pragma('journal_size_limit = 67108864');
}

export function migrationStep<T>(name: string, work: () => T): T {
    const started = Date.now();
    console.info(`[database] migration starting: ${name}`);
    try {
        const result = work();
        console.info(`[database] migration finished: ${name}`, {
            elapsedMs: Date.now() - started,
            rssMiB: Math.round(process.memoryUsage().rss / 1048576)
        });
        return result;
    } catch (error) {
        console.error(`[database] migration failed: ${name}`, error);
        throw error;
    }
}