/**
 * @fileoverview Config initialization wizard.
 * @author Ilya Volodin
 * @copyright 2015 Ilya Volodin. All rights reserved.
 */

"use strict";

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

var exec = require("child_process").exec,
    inquirer = require("inquirer"),
    ConfigFile = require("./config-file");

//------------------------------------------------------------------------------
// Private
//------------------------------------------------------------------------------

/* istanbul ignore next: hard to test fs function */
/**
 * Create .eslintrc file in the current working directory
 * @param {object} config object that contains user's answers
 * @param {string} format The file format to write to.
 * @param {function} callback function to call once the file is written.
 * @returns {void}
 */
function writeFile(config, format, callback) {

    // default is .js
    var extname = ".js";
    if (format === "YAML") {
        extname = ".yml";
    } else if (format === "JSON") {
        extname = ".json";
    }


    try {
        ConfigFile.write(config, "./.eslintrc" + extname);
        console.log("Successfully created .eslintrc" + extname + " file in " + process.cwd());
    } catch (e) {
        callback(e);
        return;
    }

    // install any external configs as well as any included plugins
    if (config.extends && config.extends.indexOf("eslint") === -1) {
        console.log("Installing additional dependencies");
        exec("npm i eslint-config-" + config.extends + " --save-dev", function(err) {

            if (err) {
                return callback(err);
            }

            // TODO: consider supporting more than 1 plugin though it's required yet.
            exec("npm i eslint-plugin-" + config.plugins[0] + " --save-dev", callback);
        });
        return;
    }

    // install the react plugin if it was explictly chosen
    if (config.plugins && config.plugins.indexOf("react") >= 0) {
        console.log("Installing React plugin");
        exec("npm i eslint-plugin-react --save-dev", callback);
        return;
    }
    callback();
}

/**
 * process user's answers and create config object
 * @param {object} answers answers received from inquirer
 * @returns {object} config object
 */
function processAnswers(answers) {
    var config = {rules: {}, env: {}, extends: "eslint:recommended"};
    config.rules.indent = [2, answers.indent];
    config.rules.quotes = [2, answers.quotes];
    config.rules["linebreak-style"] = [2, answers.linebreak];
    config.rules.semi = [2, answers.semi ? "always" : "never"];
    if (answers.es6) {
        config.env.es6 = true;
    }
    answers.env.forEach(function(env) {
        config.env[env] = true;
    });
    if (answers.jsx) {
        config.ecmaFeatures = {jsx: true};
        if (answers.react) {
            config.plugins = ["react"];
            config.ecmaFeatures.experimentalObjectRestSpread = true;
        }
    }
    return config;
}

/**
 * process user's style guide of choice and return an appropriate config object.
 * @param {string} guide name of the chosen style guide
 * @returns {object} config object
 */
function getConfigForStyleGuide(guide) {
    var guides = {
        google: {extends: "google"},
        airbnb: {extends: "airbnb", plugins: ["react"]},
        standard: {extends: "standard", plugins: ["standard"]}
    };
    if (!guides[guide]) {
        throw new Error("You referenced an unsupported guide.");
    }
    return guides[guide];
}

/* istanbul ignore next: no need to test inquirer*/
/**
 * Ask use a few questions on command prompt
 * @param {function} callback callback function when file has been written
 * @returns {void}
 */
function promptUser(callback) {
    inquirer.prompt([
        {
            type: "list",
            name: "source",
            message: "How would you like to configure ESLint?",
            default: "prompt",
            choices: [{name: "Answer questions about your style", value: "prompt"}, {name: "Use a popular style guide", value: "guide"}]
        },
        {
            type: "list",
            name: "styleguide",
            message: "Which style guide do you want to follow?",
            choices: [{name: "Google", value: "google"}, {name: "AirBnB", value: "airbnb"}, {name: "Standard", value: "standard"}],
            when: function(answers) {
                return answers.source === "guide";
            }
        },
        {
            type: "list",
            name: "format",
            message: "What format do you want your config file to be in?",
            default: "JavaScript",
            choices: ["JavaScript", "YAML", "JSON"],
            when: function(answers) {
                return answers.source === "guide";
            }
        }
    ], function(earlyAnswers) {

        // early exit if you are using a style guide
        if (earlyAnswers.source === "guide") {
            writeFile(getConfigForStyleGuide(earlyAnswers.styleguide), earlyAnswers.format, callback);
            return;
        }

        // continue with the style questions otherwise...
        inquirer.prompt([
            {
                type: "list",
                name: "indent",
                message: "What style of indentation do you use?",
                default: "tabs",
                choices: [{name: "Tabs", value: "tab"}, {name: "Spaces", value: 4}]
            },
            {
                type: "list",
                name: "quotes",
                message: "What quotes do you use for strings?",
                default: "double",
                choices: [{name: "Double", value: "double"}, {name: "Single", value: "single"}]
            },
            {
                type: "list",
                name: "linebreak",
                message: "What line endings do you use?",
                default: "unix",
                choices: [{name: "Unix", value: "unix"}, {name: "Windows", value: "windows"}]
            },
            {
                type: "confirm",
                name: "semi",
                message: "Do you require semicolons?",
                default: true
            },
            {
                type: "confirm",
                name: "es6",
                message: "Are you using ECMAScript 6 features?",
                default: false
            },
            {
                type: "checkbox",
                name: "env",
                message: "Where will your code run?",
                default: ["browser"],
                choices: [{name: "Node", value: "node"}, {name: "Browser", value: "browser"}]
            },
            {
                type: "confirm",
                name: "jsx",
                message: "Do you use JSX?",
                default: false
            },
            {
                type: "confirm",
                name: "react",
                message: "Do you use React",
                default: false,
                when: function(answers) {
                    return answers.jsx;
                }
            },
            {
                type: "list",
                name: "format",
                message: "What format do you want your config file to be in?",
                default: "JavaScript",
                choices: ["JavaScript", "YAML", "JSON"]
            }
        ], function(answers) {
            var config = processAnswers(answers);
            writeFile(config, answers.format, callback);
        });
    });
}

//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------

var init = {
    getConfigForStyleGuide: getConfigForStyleGuide,
    processAnswers: processAnswers,
    initializeConfig: /* istanbul ignore next */ function(callback) {
        promptUser(callback);
    }
};

module.exports = init;