/**
 * @fileoverview Responsible for loading ignore config files and managing ignore patterns
 * @author Jonathan Rajavuori
 */

"use strict";

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

const fs = require("fs"),
    path = require("path"),
    ignore = require("ignore"),
    shell = require("shelljs"),
    pathUtil = require("./util/path-util");

const debug = require("debug")("eslint:ignored-paths");


//------------------------------------------------------------------------------
// Constants
//------------------------------------------------------------------------------

const ESLINT_IGNORE_FILENAME = ".eslintignore";

/**
 * Adds `"*"` at the end of `"node_modules/"`,
 * so that subtle directories could be re-included by .gitignore patterns
 * such as `"!node_modules/should_not_ignored"`
 */
const DEFAULT_IGNORE_DIRS = [
    "/node_modules/*",
    "/bower_components/*"
];
const DEFAULT_OPTIONS = {
    dotfiles: false,
    cwd: process.cwd()
};


//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------


/**
 * Find an ignore file in the current directory.
 * @param {string} cwd Current working directory
 * @returns {string} Path of ignore file or an empty string.
 */
function findIgnoreFile(cwd) {
    cwd = cwd || DEFAULT_OPTIONS.cwd;

    const ignoreFilePath = path.resolve(cwd, ESLINT_IGNORE_FILENAME);

    return shell.test("-f", ignoreFilePath) ? ignoreFilePath : "";
}

/**
 * Merge options with defaults
 * @param {Object} options Options to merge with DEFAULT_OPTIONS constant
 * @returns {Object} Merged options
 */
function mergeDefaultOptions(options) {
    options = (options || {});
    return Object.assign({}, DEFAULT_OPTIONS, options);
}

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

/**
 * IgnoredPaths
 * @constructor
 * @class IgnoredPaths
 * @param {Object} options object containing 'ignore', 'ignorePath' and 'patterns' properties
 */
function IgnoredPaths(options) {

    options = mergeDefaultOptions(options);

    /**
     * add pattern to node-ignore instance
     * @param {Object} ig, instance of node-ignore
     * @param {string} pattern, pattern do add to ig
     * @returns {array} raw ignore rules
     */
    function addPattern(ig, pattern) {
        return ig.addPattern(pattern);
    }

    /**
     * add ignore file to node-ignore instance
     * @param {Object} ig, instance of node-ignore
     * @param {string} filepath, file to add to ig
     * @returns {array} raw ignore rules
     */
    function addIgnoreFile(ig, filepath) {
        ig.ignoreFiles.push(filepath);
        return ig.add(fs.readFileSync(filepath, "utf8"));
    }

    this.defaultPatterns = [].concat(DEFAULT_IGNORE_DIRS, options.patterns || []);
    this.baseDir = options.cwd;

    this.ig = {
        custom: ignore(),
        default: ignore()
    };

    // Add a way to keep track of ignored files.  This was present in node-ignore
    // 2.x, but dropped for now as of 3.0.10.
    this.ig.custom.ignoreFiles = [];
    this.ig.default.ignoreFiles = [];

    if (options.dotfiles !== true) {

        /*
         * ignore files beginning with a dot, but not files in a parent or
         * ancestor directory (which in relative format will begin with `../`).
         */
        addPattern(this.ig.default, [".*", "!../"]);
    }

    addPattern(this.ig.default, this.defaultPatterns);

    if (options.ignore !== false) {
        let ignorePath;

        if (options.ignorePath) {
            debug("Using specific ignore file");

            try {
                fs.statSync(options.ignorePath);
                ignorePath = options.ignorePath;
            } catch (e) {
                e.message = "Cannot read ignore file: " + options.ignorePath + "\nError: " + e.message;
                throw e;
            }
        } else {
            debug("Looking for ignore file in " + options.cwd);
            ignorePath = findIgnoreFile(options.cwd);

            try {
                fs.statSync(ignorePath);
                debug("Loaded ignore file " + ignorePath);
            } catch (e) {
                debug("Could not find ignore file in cwd");
                this.options = options;
            }
        }

        if (ignorePath) {
            debug("Adding " + ignorePath);
            this.baseDir = path.dirname(path.resolve(options.cwd, ignorePath));
            addIgnoreFile(this.ig.custom, ignorePath);
            addIgnoreFile(this.ig.default, ignorePath);
        }

        if (options.ignorePattern) {
            addPattern(this.ig.custom, options.ignorePattern);
            addPattern(this.ig.default, options.ignorePattern);
        }
    }

    this.options = options;

}

/**
 * Determine whether a file path is included in the default or custom ignore patterns
 * @param {string} filepath Path to check
 * @param {string} [category=null] check 'default', 'custom' or both (null)
 * @returns {boolean} true if the file path matches one or more patterns, false otherwise
 */
IgnoredPaths.prototype.contains = function(filepath, category) {

    let result = false;
    const absolutePath = path.resolve(this.options.cwd, filepath);
    const relativePath = pathUtil.getRelativePath(absolutePath, this.options.cwd);

    if ((typeof category === "undefined") || (category === "default")) {
        result = result || (this.ig.default.filter([relativePath]).length === 0);
    }

    if ((typeof category === "undefined") || (category === "custom")) {
        result = result || (this.ig.custom.filter([relativePath]).length === 0);
    }

    return result;

};

/**
 * Returns a list of dir patterns for glob to ignore
 * @returns {function()} method to check whether a folder should be ignored by glob.
 */
IgnoredPaths.prototype.getIgnoredFoldersGlobChecker = function() {

    const ig = ignore().add(DEFAULT_IGNORE_DIRS);

    if (this.options.ignore) {
        ig.add(this.ig.custom);
    }

    const filter = ig.createFilter();

    /**
     * TODO
     * 1.
     * Actually, it should be `this.options.baseDir`, which is the base dir of `ignore-path`,
     * as well as Line 177.
     * But doing this leads to a breaking change and fails tests.
     * Related to #6759
     */
    const base = this.options.cwd;

    return function(absolutePath) {
        const relative = pathUtil.getRelativePath(absolutePath, base);

        if (!relative) {
            return false;
        }

        return !filter(relative);
    };
};

module.exports = IgnoredPaths;
