ts-file-migration-provider.mts

import { consola } from 'consola'
import type { Migration, MigrationProvider } from 'kysely'
import { join } from 'pathe'
import { filename } from 'pathe/utils'
import { getFileType } from '../utils/get-file-type.mjs'
import { importTSFile } from '../utils/import-ts-file.mjs'
import { safeReaddir } from '../utils/safe-readdir.mjs'

/**
 * An opinionated migration provider that reads migrations from TypeScript files.
 * Same as `FileMigrationProvider` but works in ESM/CJS without loader flag/s,
 * and on Windows too.
 */
export class TSFileMigrationProvider implements MigrationProvider {
	readonly #props: TSFileMigrationProviderProps

	constructor(props: TSFileMigrationProviderProps) {
		this.#props = props
	}

	async getMigrations(): Promise<Record<string, Migration>> {
		const migrations: Record<string, Migration> = {}

		const files = await safeReaddir(this.#props.migrationFolder)

		for (const fileName of files) {
			const fileType = getFileType(fileName)

			const isTS = fileType === 'TS'

			if (!isTS) {
				if (!this.#props.allowJS) {
					consola.warn(`Ignoring \`${fileName}\` - not a TS file.`)
					continue
				}

				if (fileType !== 'JS') {
					consola.warn(`Ignoring \`${fileName}\` - not a TS/JS file.`)
					continue
				}
			}

			const filePath = join(this.#props.migrationFolder, fileName)

			const migration = await (isTS ? importTSFile(filePath) : import(filePath))

			const migrationKey = filename(fileName)

			if (isMigration(migration?.default)) {
				migrations[migrationKey] = migration.default
			} else if (isMigration(migration)) {
				migrations[migrationKey] = migration
			} else {
				consola.warn(`Ignoring \`${fileName}\` - not a migration.`)
			}
		}

		return migrations
	}
}

function isMigration(obj: unknown): obj is Migration {
	return (
		typeof obj === 'object' &&
		obj !== null &&
		!Array.isArray(obj) &&
		'up' in obj &&
		typeof obj.up === 'function'
	)
}

export interface TSFileMigrationProviderProps {
	allowJS?: boolean
	migrationFolder: string
}