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

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

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

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

/**
 * 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.
 */
function 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}
 */
function 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.
 */
function isErrorSeverity(ruleConfig) {
    return getRuleSeverity(ruleConfig) === 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.
 */
function isValidSeverity(ruleConfig) {
    let severity = Array.isArray(ruleConfig) ? ruleConfig[0] : ruleConfig;

    if (typeof severity === "string") {
        severity = severity.toLowerCase();
    }
    return VALID_SEVERITIES.has(severity);
}

/**
 * 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.
 */
function isEverySeverityValid(config) {
    return Object.keys(config).every(ruleId => isValidSeverity(config[ruleId]));
}

/**
 * Normalizes a value for a global in a config
 * @param {(boolean|string|null)} configuredValue The value given for a global in configuration or in
 * a global directive comment
 * @returns {("readable"|"writeable"|"off")} The value normalized as a string
 * @throws Error if global value is invalid
 */
function normalizeConfigGlobal(configuredValue) {
    switch (configuredValue) {
        case "off":
            return "off";

        case true:
        case "true":
        case "writeable":
        case "writable":
            return "writable";

        case null:
        case false:
        case "false":
        case "readable":
        case "readonly":
            return "readonly";

        default:
            throw new Error(`'${configuredValue}' is not a valid configuration for a global (use 'readonly', 'writable', or 'off')`);
    }
}

export {
    getRuleSeverity,
    normalizeToStrings,
    isErrorSeverity,
    isValidSeverity,
    isEverySeverityValid,
    normalizeConfigGlobal
};