import { config } from 'dotenv';
import { existsSync } from 'node:fs';
import { homedir } from 'node:os';
import { dirname, join, resolve } from 'node:path';
import { fileURLToPath } from 'node:url';
import { detectFromEnv, loadConfig } from '@mosaicstack/config';

type TierSource =
  | 'process environment'
  | 'daemon .env'
  | 'monorepo-root .env'
  | 'gateway-local .env'
  | 'default';

type BootSource = TierSource | 'mosaic.config.json';

const here = dirname(fileURLToPath(import.meta.url));
const daemonEnv = join(homedir(), '.config', 'mosaic', 'gateway', '.env');
const monorepoRootEnv = resolve(here, '../../..', '.env');
const gatewayLocalEnv = resolve(here, '..', '.env');

const inheritedTier = process.env['MOSAIC_STORAGE_TIER'];
let tierSource: TierSource = inheritedTier === undefined ? 'default' : 'process environment';
const inheritedDatabaseUrl = process.env['DATABASE_URL'];
let databaseUrlSource: TierSource =
  inheritedDatabaseUrl === undefined ? 'default' : 'process environment';

function loadAnchoredDotenv(
  path: string,
  sourceLabel: Exclude<TierSource, 'process environment' | 'default'>,
): void {
  if (!existsSync(path)) {
    return;
  }

  const beforeTier = process.env['MOSAIC_STORAGE_TIER'];
  const beforeDatabaseUrl = process.env['DATABASE_URL'];
  config({ path, quiet: true });

  if (
    beforeTier === undefined &&
    process.env['MOSAIC_STORAGE_TIER'] !== undefined &&
    tierSource === 'default'
  ) {
    tierSource = sourceLabel;
  }

  if (
    beforeDatabaseUrl === undefined &&
    process.env['DATABASE_URL'] !== undefined &&
    databaseUrlSource === 'default'
  ) {
    databaseUrlSource = sourceLabel;
  }
}

// Load .env from daemon config dir (global install / daemon mode) first.
// It takes precedence over file-based local-dev configuration.
loadAnchoredDotenv(daemonEnv, 'daemon .env');

// Load .env from the anchored monorepo root, then fill any remaining values
// from apps/gateway/.env when present.
loadAnchoredDotenv(monorepoRootEnv, 'monorepo-root .env');
loadAnchoredDotenv(gatewayLocalEnv, 'gateway-local .env');

const envOnlyTier = detectFromEnv().tier;
const resolvedTier = loadConfig().tier;

let source: BootSource;
if (resolvedTier !== envOnlyTier) {
  source = 'mosaic.config.json';
} else if (tierSource !== 'default') {
  source = tierSource;
} else if (envOnlyTier === 'standalone' && databaseUrlSource !== 'default') {
  source = databaseUrlSource;
} else {
  source = 'default';
}

console.info(`[gateway env] storage tier=${resolvedTier} source=${source}`);