import fs from "node:fs/promises";
import path from "node:path";
import type { SqlDependency } from "../core/types.ts";

import {
	loadMigration,
	Migrator,
	type MigratorOptions,
} from "../core/migrator.ts";
import {
	executePostgresMigration,
	getPostgresMigrations,
	postgresBootstrapMigration,
} from "../postgres/mod.ts";

const migrationExtensions = new Set([".ts", ".js"]);

export interface PostgresMigratorOptions {
	sql: unknown;
	directory: URL;
}

/**
 * Create a standardish Postgres Migrator based on the filesystem and an sql connection from [postgres.js](https://github.com/porsager/postgres)
 *
 * ```js
 * const sql = postgres(…)
 *
 * const migrator = getPostgresMigratorOptions({
 * 	sql,
 * 	directory: new URL("./migrations/", import.meta.url)
 * })
 *
 * ```
 */
export function getPostgresMigratorOptions({
	sql,
	directory,
}: PostgresMigratorOptions): MigratorOptions<SqlDependency> {
	return {
		getRecords() {
			return getPostgresMigrations(sql as SqlDependency);
		},

		execute(def, direction) {
			return executePostgresMigration(def, direction, sql as SqlDependency);
		},

		async getDefinitions() {
			const migrations = [
				{ name: "000-bootstrap.js", ...postgresBootstrapMigration },
			];

			const files = await fs.readdir(directory, {
				withFileTypes: true,
			});

			for (const stat of files) {
				if (!stat.isFile()) continue;
				if (!migrationExtensions.has(path.extname(stat.name))) continue;

				migrations.push(await loadMigration(stat.name, directory));
			}

			return migrations.sort((a, b) => a.name.localeCompare(b.name));
		},
	};
}

/** @deprecated use {@link getPostgresMigratorOptions} */
export const getNodePostgresMigratorOptions = getPostgresMigratorOptions;

/**
 * This is a syntax sugar for `new Migrator(getPostgresMigratorOptions(...))`
 *
 * @param {PostgresMigratorOptions} options
 */
export function getPostgresMigrator(options: PostgresMigratorOptions) {
	if (!options.directory.pathname.endsWith("/")) {
		throw new Error("Postgres migration directory must end with a '/'");
	}
	return new Migrator(getPostgresMigratorOptions(options));
}

/** @deprecated use {@link getPostgresMigrator} */
export const getNodePostgresMigrator = getPostgresMigrator;