var gutil = require('gulp-util');
var extend = require('util-extend');
var sort = require('sort-object');
var through = require('through2');
var util = require('util');

var expand = require('expand-hash');
var frontmatter = require('front-matter');
var marked = require('marked');

var NAME = 'gulp-markdown-to-json';
var PluginError = gutil.PluginError;
var streamingErr = new PluginError(NAME, 'Streaming not supported');

function parse(file, flatten) {
    if (file.isNull()) return;
    if (file.isStream()) return this.emit('error', streamingErr);

    if (file.isBuffer()) {
        var path = file.relative.split('.').shift().replace(/[\/\\]/g, '.');
        var parsed = frontmatter(file.contents.toString());

        var body = parsed.body.split(/\n/);
        var markup = marked(parsed.body).split(/\n/);

        var title = markup[0].substr(0, 3) === '<h1' ?
            body[0] :
            false;

        var data = {};
        data[path] = parsed.attributes;

        if (title && !data[path].title) {
            data[path].title = (title.substr(0, 1) === '#') ?
                title.substr(2) :
                title;
            data[path].body = markup.slice(1).join(' ');
        } else {
            data[path].body = marked(parsed.body);
        }

        if (flatten) data = data[path];

        file.path = gutil.replaceExtension(file.path, '.json');
        file.contents = new Buffer(JSON.stringify(data));

        return file;
    }
}

module.exports = function(config, marked_options) {
    var options = config && marked_options ?
        marked_options :
        config;

    marked.setOptions(options);

    var stream = through.obj(function(input, enc, callback) {
        var file;

        if (util.isArray(input)) {
            var data = {};

            input.forEach(function(file) {
                var file_data = JSON.parse(parse(file).contents.toString());

                data = extend(file_data, data);
            });

            var tree = sort(expand(data));
            var json = JSON.stringify(tree);

            var name = config && typeof config === 'string' ?
                config :
                'content.json';

            file = new gutil.File({
                base: '/',
                cwd: '/',
                path: '/' + name,
                contents: new Buffer(json)
            });
        } else {
            file = parse(input, true);
        }

        this.push(file);
        callback();
    });

    return stream;
};