/*************************************************************
 *
 *  Copyright (c) 2017 The MathJax Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

/**
 * @fileoverview  Implements the CssStyles class for handling stylesheets
 *
 * @author dpvc@mathjax.org (Davide Cervone)
 */

/**
 * The data for a selector
 */
export type StyleData = {
    [property: string]: string | number;
};

/**
 * A list of selectors and their data (basically a stylesheet)
 */
export type StyleList = {
    [selector: string]: StyleData;
};

/******************************************************************************/
/**
 * The CssStyles class (for managing a collection of CSS style definitions)
 */

export class CssStyles {
    /**
     * The styles as they currently stand
     */
    protected styles: StyleList = {};

    /**
     * @return {string}  The styles as a CSS string
     */
    get cssText() {
        return this.getStyleString();
    }

    /**
     * @param {StyleList} styles  The initial styles to use, if any
     * @constructor
     */
    constructor(styles: StyleList = null) {
        this.addStyles(styles);
    }

    /**
     * @param {StyleList} styles  The styles to combine with the existing ones
     */
    public addStyles(styles: StyleList) {
        if (!styles) return;
        for (const style of Object.keys(styles)) {
            if (!this.styles[style]) {
                this.styles[style] = {};
            }
            Object.assign(this.styles[style], styles[style]);
        }
    }

    /**
     * @param {string[]} selectors  The selectors for the styles to remove
     */
    public removeStyles(...selectors: string[]) {
        for (const selector of selectors) {
            delete this.styles[selector];
        }
    }

    /**
     * Clear all the styles
     */
    clear() {
        this.styles = {};
    }

    /**
     * @return {string} The CSS string for the style list
     */
    public getStyleString() {
        const selectors = Object.keys(this.styles);
        const defs: string[] = new Array(selectors.length);
        let i = 0;
        for (const selector of selectors) {
            defs[i++] = selector + ' {\n' + this.getStyleDefString(this.styles[selector]) + '\n}';
        }
        return defs.join('\n\n');
    }

    /**
     * @param {StyleData} styles  The style data to be stringified
     * @return {string}           The CSS string for the given data
     */
    public getStyleDefString(styles: StyleData) {
        const properties = Object.keys(styles);
        const values: string[] = new Array(properties.length);
        let i = 0;
        for (const property of properties) {
            values[i++] = '  ' + property + ': ' + styles[property] + ';';
        }
        return values.join('\n');
    }

}