import Declaration from './declaration';
import Processor   from './processor';
import stringify   from './stringify';
import Comment     from './comment';
import AtRule      from './at-rule';
import vendor      from './vendor';
import parse       from './parse';
import list        from './list';
import Rule        from './rule';
import Root        from './root';

/**
 * Create a new {@link Processor} instance that will apply `plugins`
 * as CSS processors.
 *
 * @param {Array.<Plugin|pluginFunction>|Processor} plugins - PostCSS
 *        plugins. See {@link Processor#use} for plugin format.
 *
 * @return {Processor} Processor to process multiple CSS
 *
 * @example
 * import postcss from 'postcss';
 *
 * postcss(plugins).process(css, { from, to }).then(result => {
 *   console.log(result.css);
 * });
 *
 * @namespace postcss
 */
function postcss(...plugins) {
    if ( plugins.length === 1 && Array.isArray(plugins[0]) ) {
        plugins = plugins[0];
    }
    return new Processor(plugins);
}

/**
 * Creates a PostCSS plugin with a standard API.
 *
 * The newly-wrapped function will provide both the name and PostCSS
 * version of the plugin.
 *
 * ```js
 *  const processor = postcss([replace]);
 *  processor.plugins[0].postcssPlugin  //=> 'postcss-replace'
 *  processor.plugins[0].postcssVersion //=> '5.1.0'
 * ```
 *
 * The plugin function receives 2 arguments: {@link Root}
 * and {@link Result} instance. The function should mutate the provided
 * `Root` node. Alternatively, you can create a new `Root` node
 * and override the `result.root` property.
 *
 * ```js
 * const cleaner = postcss.plugin('postcss-cleaner', () => {
 *   return (root, result) => {
 *     result.root = postcss.root();
 *   };
 * });
 * ```
 *
 * As a convenience, plugins also expose a `process` method so that you can use
 * them as standalone tools.
 *
 * ```js
 * cleaner.process(css, options);
 * // This is equivalent to:
 * postcss([ cleaner(options) ]).process(css);
 * ```
 *
 * Asynchronous plugins should return a `Promise` instance.
 *
 * ```js
 * postcss.plugin('postcss-import', () => {
 *   return (root, result) => {
 *     return new Promise( (resolve, reject) => {
 *       fs.readFile('base.css', (base) => {
 *         root.prepend(base);
 *         resolve();
 *       });
 *     });
 *   };
 * });
 * ```
 *
 * Add warnings using the {@link Node#warn} method.
 * Send data to other plugins using the {@link Result#messages} array.
 *
 * ```js
 * postcss.plugin('postcss-caniuse-test', () => {
 *   return (root, result) => {
 *     css.walkDecls(decl => {
 *       if ( !caniuse.support(decl.prop) ) {
 *         decl.warn(result, 'Some browsers do not support ' + decl.prop);
 *       }
 *     });
 *   };
 * });
 * ```
 *
 * @param {string} name          - PostCSS plugin name. Same as in `name`
 *                                 property in `package.json`. It will be saved
 *                                 in `plugin.postcssPlugin` property.
 * @param {function} initializer - will receive plugin options
 *                                 and should return {@link pluginFunction}
 *
 * @return {Plugin} PostCSS plugin
 */
postcss.plugin = function plugin(name, initializer) {
    let creator = function (...args) {
        let transformer = initializer(...args);
        transformer.postcssPlugin  = name;
        transformer.postcssVersion = (new Processor()).version;
        return transformer;
    };

    let cache;
    Object.defineProperty(creator, 'postcss', {
        get() {
            if ( !cache ) cache = creator();
            return cache;
        }
    });

    creator.process = function (root, opts) {
        return postcss([ creator(opts) ]).process(root, opts);
    };

    return creator;
};

/**
 * Default function to convert a node tree into a CSS string.
 *
 * @param {Node} node       - start node for stringifing. Usually {@link Root}.
 * @param {builder} builder - function to concatenate CSS from node’s parts
 *                            or generate string and source map
 *
 * @return {void}
 *
 * @function
 */
postcss.stringify = stringify;

/**
 * Parses source css and returns a new {@link Root} node,
 * which contains the source CSS nodes.
 *
 * @param {string|toString} css   - string with input CSS or any object
 *                                  with toString() method, like a Buffer
 * @param {processOptions} [opts] - options with only `from` and `map` keys
 *
 * @return {Root} PostCSS AST
 *
 * @example
 * // Simple CSS concatenation with source map support
 * const root1 = postcss.parse(css1, { from: file1 });
 * const root2 = postcss.parse(css2, { from: file2 });
 * root1.append(root2).toResult().css;
 *
 * @function
 */
postcss.parse = parse;

/**
 * @member {vendor} - Contains the {@link vendor} module.
 *
 * @example
 * postcss.vendor.unprefixed('-moz-tab') //=> ['tab']
 */
postcss.vendor = vendor;

/**
 * @member {list} - Contains the {@link list} module.
 *
 * @example
 * postcss.list.space('5px calc(10% + 5px)') //=> ['5px', 'calc(10% + 5px)']
 */
postcss.list = list;

/**
 * Creates a new {@link Comment} node.
 *
 * @param {object} [defaults] - properties for the new node.
 *
 * @return {Comment} new Comment node
 *
 * @example
 * postcss.comment({ text: 'test' })
 */
postcss.comment = defaults => new Comment(defaults);

/**
 * Creates a new {@link AtRule} node.
 *
 * @param {object} [defaults] - properties for the new node.
 *
 * @return {AtRule} new AtRule node
 *
 * @example
 * postcss.atRule({ name: 'charset' }).toString() //=> "@charset"
 */
postcss.atRule = defaults => new AtRule(defaults);

/**
 * Creates a new {@link Declaration} node.
 *
 * @param {object} [defaults] - properties for the new node.
 *
 * @return {Declaration} new Declaration node
 *
 * @example
 * postcss.decl({ prop: 'color', value: 'red' }).toString() //=> "color: red"
 */
postcss.decl = defaults => new Declaration(defaults);

/**
 * Creates a new {@link Rule} node.
 *
 * @param {object} [defaults] - properties for the new node.
 *
 * @return {AtRule} new Rule node
 *
 * @example
 * postcss.rule({ selector: 'a' }).toString() //=> "a {\n}"
 */
postcss.rule = defaults => new Rule(defaults);

/**
 * Creates a new {@link Root} node.
 *
 * @param {object} [defaults] - properties for the new node.
 *
 * @return {Root} new Root node
 *
 * @example
 * postcss.root({ after: '\n' }).toString() //=> "\n"
 */
postcss.root = defaults => new Root(defaults);

export default postcss;