/*
	MIT License http://www.opensource.org/licenses/mit-license.php
*/

"use strict";

const RuntimeGlobals = require("../RuntimeGlobals");
const RuntimeModule = require("../RuntimeModule");
const { entryModuleIdExpression } = require("../javascript/StartupHelpers");

/** @import Chunk from "../Chunk" */
/** @import Compilation from "../Compilation" */

class StartupEntrypointRuntimeModule extends RuntimeModule {
	/**
	 * Returns true, if the runtime module should get it's own scope.
	 * When false, `generate()` must emit complete statements ending with `;`
	 * so a following runtime IIFE is not parsed as a call (ASI).
	 * @returns {boolean} true, if the runtime module should get it's own scope
	 */
	shouldIsolate() {
		return false;
	}

	/**
	 * @param {boolean} asyncChunkLoading use async chunk loading
	 */
	constructor(asyncChunkLoading) {
		super("startup entrypoint");
		/** @type {boolean} */
		this.asyncChunkLoading = asyncChunkLoading;
	}

	/**
	 * Generates runtime code for this runtime module.
	 * @returns {string | null} runtime code
	 */
	generate() {
		const compilation = /** @type {Compilation} */ (this.compilation);
		const { runtimeTemplate, chunkGraph } = compilation;
		const chunk = /** @type {Chunk} */ (this.chunk);
		const cst = runtimeTemplate.renderConst();
		return `${
			RuntimeGlobals.startupEntrypoint
		} = ${runtimeTemplate.basicFunction("result, chunkIds, fn", [
			"// arguments: chunkIds, moduleId are deprecated",
			`${cst} moduleId = chunkIds;`,
			`if(!fn) chunkIds = result, fn = ${runtimeTemplate.returningFunction(
				`${RuntimeGlobals.require}(${entryModuleIdExpression(
					chunkGraph,
					chunk,
					"moduleId"
				)})`
			)};`,
			...(this.asyncChunkLoading
				? [
						`return Promise.all(chunkIds.map(${RuntimeGlobals.ensureChunk}, ${
							RuntimeGlobals.require
						})).then(${runtimeTemplate.basicFunction("", [
							`${cst} r = fn();`,
							"return r === undefined ? result : r;"
						])})`
					]
				: [
						`chunkIds.map(${RuntimeGlobals.ensureChunk}, ${RuntimeGlobals.require})`,
						`${cst} r = fn();`,
						"return r === undefined ? result : r;"
					])
		])};`;
	}
}

module.exports = StartupEntrypointRuntimeModule;