import { Compiler, Plugin } from "webpack";
import ts from "typescript";

const fs = require("fs");
const path = require("path");

const findPackageData = require("@babel/core/lib/config/files/package")
    .findPackageData;
const findRelativeConfig = require("@babel/core/lib/config/files/configuration")
    .findRelativeConfig;
const findRootConfig = require("@babel/core/lib/config/files/configuration")
    .findRootConfig;

export interface FrontlineJsConfigWebpackPluginOptions {
    mode: "production" | "development" | "none";
    browserslistEnv: string;
    babelConfigFile?: string;
    tsConfigFile?: string;
}

const defaultConfig = {
    browserslistEnv: "legacy"
};

export class FrontlineJsConfigWebpackPlugin implements Plugin {
    options: Partial<FrontlineJsConfigWebpackPluginOptions>;

    constructor(options?: Partial<FrontlineJsConfigWebpackPluginOptions>) {
        this.options = Object.assign({}, defaultConfig, options);
    }

    resolveBabelConfigFilePath(
        contextPath: string,
        environmentName: "production" | "development" | "none" | undefined
    ) {
        // From https://github.com/babel/babel/blob/52a569056c6008c453bf26219461655c7d0322c4/packages/babel-core/src/config/files/package.js#L15
        const packageData = findPackageData(contextPath);
        // needed because babels `findRelativeConfig` search just in parent directories
        packageData.directories.push(packageData.filepath);
        // From https://github.com/babel/babel/blob/52a569056c6008c453bf26219461655c7d0322c4/packages/babel-core/src/config/files/configuration.js#L26
        const resolvedRelativeConfig = findRelativeConfig(
            packageData,
            environmentName
        );
        const resolvedRootConfig = findRootConfig(
            packageData.filepath,
            environmentName
        );

        // babel.config.js
        if (resolvedRootConfig && resolvedRootConfig.filepath) {
            return resolvedRootConfig.filepath;
        }

        // .babelrc.js and .babelrc
        if (resolvedRelativeConfig && resolvedRelativeConfig.config) {
            return resolvedRelativeConfig.config.filepath;
        }

        return path.resolve(__dirname, "./babel.config.js");
    }

    userHasTsConfigFile(
        contextPath: string = path.resolve(process.cwd(), "tsconfig.json")
    ) {
        const { config, error } = ts.readConfigFile(
            contextPath,
            ts.sys.readFile
        );

        if (error) {
            return false;
        }

        return !!config;
    }

    apply(compiler: Compiler): void {
        const defaultOptions = {
            babelConfigFile:
                this.options.babelConfigFile ||
                this.resolveBabelConfigFilePath(
                    compiler.context,
                    compiler.options.mode || this.options.mode
                ),
            tsConfigFile: this.userHasTsConfigFile(this.options.tsConfigFile)
        };

        const options = Object.assign(this.options, defaultOptions);

        // From https://github.com/webpack/webpack/blob/3366421f1784c449f415cda5930a8e445086f688/lib/WebpackOptionsDefaulter.js#L12-L14
        const isProductionLikeMode =
            this.options.mode !== undefined
                ? this.options.mode === "production"
                : compiler.options.mode === "production" ||
                  !compiler.options.mode;

        const config = isProductionLikeMode
            ? require("./production.config")(
                  Object.assign({ mode: "production" }, options)
              )
            : require("./development.config")(
                  Object.assign({ mode: "development" }, options)
              );

        config.plugins.forEach((plugin: any) => plugin.apply(compiler));

        compiler.hooks.afterEnvironment.tap(
            "FrontlineJsConfigWebpackPlugin",
            () => {
                compiler.options.module!.rules.push(...config.module.rules);
            }
        );

        const javascriptExtensions = [
            ".ts",
            ".tsx",
            ".js",
            ".jsx",
            ".mjs"
        ].filter(ext => !compiler.options.resolve!.extensions!.includes(ext));

        compiler.options.resolve!.extensions!.unshift(...javascriptExtensions);
    }
}