/**
 * @fileoverview Config file operations. This file must be usable in the browser,
 * so no Node-specific code can be here.
 * @author Nicholas C. Zakas
 */
"use strict";

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

const minimatch = require("minimatch"),
    path = require("path");

const debug = require("debug")("eslint:config-ops");

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

const RULE_SEVERITY_STRINGS = ["off", "warn", "error"],
    RULE_SEVERITY = RULE_SEVERITY_STRINGS.reduce((map, value, index) => {
        map[value] = index;
        return map;
    }, {}),
    VALID_SEVERITIES = [0, 1, 2, "off", "warn", "error"];

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

module.exports = {

    /**
     * Creates an empty configuration object suitable for merging as a base.
     * @returns {Object} A configuration object.
     */
    createEmptyConfig() {
        return {
            globals: {},
            env: {},
            rules: {},
            parserOptions: {}
        };
    },

    /**
     * Creates an environment config based on the specified environments.
     * @param {Object<string,boolean>} env The environment settings.
     * @param {Environments} envContext The environment context.
     * @returns {Object} A configuration object with the appropriate rules and globals
     *      set.
     */
    createEnvironmentConfig(env, envContext) {

        const envConfig = this.createEmptyConfig();

        if (env) {

            envConfig.env = env;

            Object.keys(env).filter(name => env[name]).forEach(name => {
                const environment = envContext.get(name);

                if (environment) {
                    debug(`Creating config for environment ${name}`);
                    if (environment.globals) {
                        Object.assign(envConfig.globals, environment.globals);
                    }

                    if (environment.parserOptions) {
                        Object.assign(envConfig.parserOptions, environment.parserOptions);
                    }
                }
            });
        }

        return envConfig;
    },

    /**
     * Given a config with environment settings, applies the globals and
     * ecmaFeatures to the configuration and returns the result.
     * @param {Object} config The configuration information.
     * @param {Environments} envContent env context.
     * @returns {Object} The updated configuration information.
     */
    applyEnvironments(config, envContent) {
        if (config.env && typeof config.env === "object") {
            debug("Apply environment settings to config");
            return this.merge(this.createEnvironmentConfig(config.env, envContent), config);
        }

        return config;
    },

    /**
     * Merges two config objects. This will not only add missing keys, but will also modify values to match.
     * @param {Object} target config object
     * @param {Object} src config object. Overrides in this config object will take priority over base.
     * @param {boolean} [combine] Whether to combine arrays or not
     * @param {boolean} [isRule] Whether its a rule
     * @returns {Object} merged config object.
     */
    merge: function deepmerge(target, src, combine, isRule) {

        /*
         The MIT License (MIT)

         Copyright (c) 2012 Nicholas Fisher

         Permission is hereby granted, free of charge, to any person obtaining a copy
         of this software and associated documentation files (the "Software"), to deal
         in the Software without restriction, including without limitation the rights
         to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
         copies of the Software, and to permit persons to whom the Software is
         furnished to do so, subject to the following conditions:

         The above copyright notice and this permission notice shall be included in
         all copies or substantial portions of the Software.

         THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
         IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
         FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
         AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
         LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
         OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
         THE SOFTWARE.
         */

        /*
         * This code is taken from deepmerge repo
         * (https://github.com/KyleAMathews/deepmerge)
         * and modified to meet our needs.
         */
        const array = Array.isArray(src) || Array.isArray(target);
        let dst = array && [] || {};

        combine = !!combine;
        isRule = !!isRule;
        if (array) {
            target = target || [];

            // src could be a string, so check for array
            if (isRule && Array.isArray(src) && src.length > 1) {
                dst = dst.concat(src);
            } else {
                dst = dst.concat(target);
            }
            if (typeof src !== "object" && !Array.isArray(src)) {
                src = [src];
            }
            Object.keys(src).forEach((e, i) => {
                e = src[i];
                if (typeof dst[i] === "undefined") {
                    dst[i] = e;
                } else if (typeof e === "object") {
                    if (isRule) {
                        dst[i] = e;
                    } else {
                        dst[i] = deepmerge(target[i], e, combine, isRule);
                    }
                } else {
                    if (!combine) {
                        dst[i] = e;
                    } else {
                        if (dst.indexOf(e) === -1) {
                            dst.push(e);
                        }
                    }
                }
            });
        } else {
            if (target && typeof target === "object") {
                Object.keys(target).forEach(key => {
                    dst[key] = target[key];
                });
            }
            Object.keys(src).forEach(key => {
                if (key === "overrides") {
                    dst[key] = (target[key] || []).concat(src[key] || []);
                } else if (Array.isArray(src[key]) || Array.isArray(target[key])) {
                    dst[key] = deepmerge(target[key], src[key], key === "plugins" || key === "extends", isRule);
                } else if (typeof src[key] !== "object" || !src[key] || key === "exported" || key === "astGlobals") {
                    dst[key] = src[key];
                } else {
                    dst[key] = deepmerge(target[key] || {}, src[key], combine, key === "rules");
                }
            });
        }

        return dst;
    },

    /**
     * Normalizes the severity value of a rule's configuration to a number
     * @param {(number|string|[number, ...*]|[string, ...*])} ruleConfig A rule's configuration value, generally
     * received from the user. A valid config value is either 0, 1, 2, the string "off" (treated the same as 0),
     * the string "warn" (treated the same as 1), the string "error" (treated the same as 2), or an array
     * whose first element is one of the above values. Strings are matched case-insensitively.
     * @returns {(0|1|2)} The numeric severity value if the config value was valid, otherwise 0.
     */
    getRuleSeverity(ruleConfig) {
        const severityValue = Array.isArray(ruleConfig) ? ruleConfig[0] : ruleConfig;

        if (severityValue === 0 || severityValue === 1 || severityValue === 2) {
            return severityValue;
        }

        if (typeof severityValue === "string") {
            return RULE_SEVERITY[severityValue.toLowerCase()] || 0;
        }

        return 0;
    },

    /**
     * Converts old-style severity settings (0, 1, 2) into new-style
     * severity settings (off, warn, error) for all rules. Assumption is that severity
     * values have already been validated as correct.
     * @param {Object} config The config object to normalize.
     * @returns {void}
     */
    normalizeToStrings(config) {

        if (config.rules) {
            Object.keys(config.rules).forEach(ruleId => {
                const ruleConfig = config.rules[ruleId];

                if (typeof ruleConfig === "number") {
                    config.rules[ruleId] = RULE_SEVERITY_STRINGS[ruleConfig] || RULE_SEVERITY_STRINGS[0];
                } else if (Array.isArray(ruleConfig) && typeof ruleConfig[0] === "number") {
                    ruleConfig[0] = RULE_SEVERITY_STRINGS[ruleConfig[0]] || RULE_SEVERITY_STRINGS[0];
                }
            });
        }
    },

    /**
     * Determines if the severity for the given rule configuration represents an error.
     * @param {int|string|Array} ruleConfig The configuration for an individual rule.
     * @returns {boolean} True if the rule represents an error, false if not.
     */
    isErrorSeverity(ruleConfig) {

        let severity = Array.isArray(ruleConfig) ? ruleConfig[0] : ruleConfig;

        if (typeof severity === "string") {
            severity = RULE_SEVERITY[severity.toLowerCase()] || 0;
        }

        return (typeof severity === "number" && severity === 2);
    },

    /**
     * Checks whether a given config has valid severity or not.
     * @param {number|string|Array} ruleConfig - The configuration for an individual rule.
     * @returns {boolean} `true` if the configuration has valid severity.
     */
    isValidSeverity(ruleConfig) {
        let severity = Array.isArray(ruleConfig) ? ruleConfig[0] : ruleConfig;

        if (typeof severity === "string") {
            severity = severity.toLowerCase();
        }
        return VALID_SEVERITIES.indexOf(severity) !== -1;
    },

    /**
     * Checks whether every rule of a given config has valid severity or not.
     * @param {Object} config - The configuration for rules.
     * @returns {boolean} `true` if the configuration has valid severity.
     */
    isEverySeverityValid(config) {
        return Object.keys(config).every(ruleId => this.isValidSeverity(config[ruleId]));
    },

    /**
     * Merges all configurations in a given config vector. A vector is an array of objects, each containing a config
     * file path and a list of subconfig indices that match the current file path. All config data is assumed to be
     * cached.
     * @param {Array<Object>} vector list of config files and their subconfig indices that match the current file path
     * @param {Object} configCache the config cache
     * @returns {Object} config object
     */
    getConfigFromVector(vector, configCache) {

        const cachedConfig = configCache.getMergedVectorConfig(vector);

        if (cachedConfig) {
            return cachedConfig;
        }

        debug("Using config from partial cache");

        const subvector = Array.from(vector);
        let nearestCacheIndex = subvector.length - 1,
            partialCachedConfig;

        while (nearestCacheIndex >= 0) {
            partialCachedConfig = configCache.getMergedVectorConfig(subvector);
            if (partialCachedConfig) {
                break;
            }
            subvector.pop();
            nearestCacheIndex--;
        }

        if (!partialCachedConfig) {
            partialCachedConfig = {};
        }

        let finalConfig = partialCachedConfig;

        // Start from entry immediately following nearest cached config (first uncached entry)
        for (let i = nearestCacheIndex + 1; i < vector.length; i++) {
            finalConfig = this.mergeVectorEntry(finalConfig, vector[i], configCache);
            configCache.setMergedVectorConfig(vector.slice(0, i + 1), finalConfig);
        }

        return finalConfig;
    },

    /**
     * Merges the config options from a single vector entry into the supplied config.
     * @param {Object} config the base config to merge the vector entry's options into
     * @param {Object} vectorEntry a single entry from a vector, consisting of a config file path and an array of
     * matching override indices
     * @param {Object} configCache the config cache
     * @returns {Object} merged config object
     */
    mergeVectorEntry(config, vectorEntry, configCache) {
        const vectorEntryConfig = Object.assign({}, configCache.getConfig(vectorEntry.filePath));
        let mergedConfig = Object.assign({}, config),
            overrides;

        if (vectorEntryConfig.overrides) {
            overrides = vectorEntryConfig.overrides.filter(
                (override, overrideIndex) => vectorEntry.matchingOverrides.indexOf(overrideIndex) !== -1
            );
        } else {
            overrides = [];
        }

        mergedConfig = this.merge(mergedConfig, vectorEntryConfig);

        delete mergedConfig.overrides;

        mergedConfig = overrides.reduce((lastConfig, override) => this.merge(lastConfig, override), mergedConfig);

        if (mergedConfig.filePath) {
            delete mergedConfig.filePath;
            delete mergedConfig.baseDirectory;
        } else if (mergedConfig.files) {
            delete mergedConfig.files;
        }

        return mergedConfig;
    },

    /**
     * Checks that the specified file path matches all of the supplied glob patterns.
     * @param {string} filePath The file path to test patterns against
     * @param {string|string[]} patterns One or more glob patterns, of which at least one should match the file path
     * @param {string|string[]} [excludedPatterns] One or more glob patterns, of which none should match the file path
     * @returns {boolean} True if all the supplied patterns match the file path, false otherwise
     */
    pathMatchesGlobs(filePath, patterns, excludedPatterns) {
        const patternList = [].concat(patterns);
        const excludedPatternList = [].concat(excludedPatterns || []);

        patternList.concat(excludedPatternList).forEach(pattern => {
            if (path.isAbsolute(pattern) || pattern.includes("..")) {
                throw new Error(`Invalid override pattern (expected relative path not containing '..'): ${pattern}`);
            }
        });

        const opts = { matchBase: true };

        return patternList.some(pattern => minimatch(filePath, pattern, opts)) &&
            !excludedPatternList.some(excludedPattern => minimatch(filePath, excludedPattern, opts));
    }
};
