var irc = require('irc');
var express = require('express');
var bodyParser = require('body-parser');
var request = require('request');
var cheerio = require('cheerio');

var config = require('./config');

// Bind recipients to notifications.
var channels = [];
var hookToChannel = {};
for (var who in config.reports) {
    if (who.indexOf('#') === 0)
        channels.push(who);

    var hooks = config.reports[who];
    for (var i = 0; i < hooks.length; i++) {
        var hook = hooks[i];
        (hookToChannel[hook] = hookToChannel[hook] || []).push(who);
    }
}

// Sanitize projectUrl
if (typeof config.projectUrl !== 'undefined') {
    var url = '' + config.projectUrl;
    if (url[url.length - 1] !== '/') {
        url += '/';
    }
    config.projectUrl = url;
}

var client = new irc.Client(config.server, config.nick, {
    debug: config.debug || false,
    channels: channels,
    userName: config.userName,
    realName: config.realName,
    retryDelay: 120000
});

var mergeRequests = {};

var app = express();

app.use(bodyParser.json()); // for parsing application/json
app.use(bodyParser.urlencoded({ extended: true })); // for parsing application/x-www-form-urlencoded

var shortenURL = function(url, callback) { callback(url); };

if (config.lstu) {
    if (config.lstu[config.lstu.length - 1] !== '/') {
        config.lstu += '/';
    }

    shortenURL = function shortenURL(url, callback) {
        request(config.lstu + 'a', { method: 'POST', form: { lsturl: url, format: 'json' } }, function (err, res, body) {
            try {
                body = JSON.parse(body);
            } catch(err) {
                body = {err: 'cant parse JSON'};
            }
            if (err || !body.success) {
                console.error("Error when shortening link: ",
                              res ? "(status: " + res.statusCode + ")" : "(no response)",
                              '\nerror:', err,
                              '\nfailure reason:', body.msg);
                callback(url);
            } else {
                callback(body.short);
            }
        });
    };
}

var handlers = {

    push: function(body, say) {
        var user = body.user_name;
        var projectName = body.project.name;

        var commits = body.commits;
        var numCommits = body.total_commits_count;

        var branchName = body.ref.replace('refs/heads/', '');

        var msg = null;
        if (!numCommits) {
            // Special case: a branch was created or deleted.
            var action = 'created';
            if (body.after === '0000000000000000000000000000000000000000')
                action = 'deleted';
            msg = projectName + ': ' + user + ' ' + action + ' branch ' + branchName;
            say(msg);
        } else {
            var maybeS = numCommits === 1 ? '' : 's';
            var lastCommit = commits[0];
            var lastCommitMessage = lastCommit.message.trim().split('\n')[0].trim();
            shortenURL(lastCommit.url, function(shortUrl) {
                msg = 'push on ' + projectName + '@' + branchName + ' (by ' + user + '): ' +
                      commits.length + ' commit' + maybeS + ' (last: ' + lastCommitMessage + ') ' + shortUrl;
                say(msg);
            });
        }
    },

    issue: function(body, say) {
        var user = body.user.name;
        var projectName = body.project.name;

        var issue = body.object_attributes;
        var issueNumber = issue.iid;
        var issueTitle = issue.title.trim();
        var issueState = issue.state;
        var url = issue.url;

        // Don't trigger the hook on issue's update;
        if (issue.action === 'update')
            return;

        shortenURL(url, function(shortUrl) {
            var msg = projectName + ': issue #' + issueNumber + ' ("' + issueTitle + '") changed state ("' + issueState + '") ' + shortUrl;
            say(msg);
        });
    },

    merge_request: function(body, say) {
        var user = body.user.name;

        var request = body.object_attributes;

        var projectName = request.target.name;

        var from = request.source_branch;
        var to = request.target_branch;

        var id = request.iid;
        var title = request.title.trim();
        var url = request.url;
        var state = request.state;

        if (typeof mergeRequests[id] === 'undefined') {
            mergeRequests[id] = {
                state: state
            };

            // Stay silent if the merge request state is open and we didn't
            // know it before.
            if (state === "opened") {
                return;
            }
        } else {
            var formerState = mergeRequests[id].state;
            mergeRequests[id].state = state;

            // Abort if the state hasn't changed.
            if (state === formerState) {
                return;
            }
        }

        shortenURL(url, function(shortUrl) {
            var msg = projectName + ': MR# ' + id + ' (' + from + '->' + to + ': ' + title + ') ' +
                      ' has been ' + state + '; ' + shortUrl;
            say(msg);
        });
    },

    build: function(body, say) {

        var id = body.build_id;
        var status = body.build_status;

        var isFinished = body.build_finished_at !== null;
        var duration = body.build_duration;

        var projectName = body.project_name;
        var stage = body.build_stage;

        var msg = projectName + ': build #' + id + ' (' + stage + ') changed status: ' + status;
        if (isFinished)
            msg += ' (finished in ' + duration + ' seconds.)';

        say(msg);
    }

};

function makeSay(body) {
    var whom = hookToChannel[body.object_kind] || [];
    return function say(msgs) {
        if (!whom.length) {
            return;
        }
        if (msgs) {
            if (msgs instanceof Array) {
                for (var i = 0; i < msgs.length; i++)
                    client.say(whom, msgs[i]);
            } else {
                client.say(whom, msgs);
            }
        }
    };
}

app.post('/', function(req, res) {
    var body = req.body || {};

    var msgs = null;
    if (body.object_kind && handlers[body.object_kind])
        handlers[body.object_kind](body, makeSay(body));
    else
        console.log("Unexpected object_kind:", body.object_kind);

    res.sendStatus(200);
});

app.listen(config.port, config.hostname, function() {
    console.log('gitlab-to-irc running.');

    var issueRegexp = /#(\d+)/g;
    var mergeRequestRegexp = /!(\d+)/g;
    client.on('message', function(from, chan, message) {
        var matches = null;
        while ((matches = issueRegexp.exec(message)) !== null) {
            var issueId = matches[1];
            var url = config.projectUrl + 'issues/' + issueId;
            request(url, function(err, res, body) {
                if (res && res.statusCode === '200') {
                    var title = cheerio.load(body)('head title').text();
                    if (title.length) {
                        client.say(chan, title);
                    } else {
                        client.say(chan, "Issue #" + issueId + ": " + url);
                    }
                }
            });
        }

        while ((matches = mergeRequestRegexp.exec(message)) !== null) {
            var mrId = matches[1];
            var url = config.projectUrl + 'merge_requests/' + mrId;
            request(url, function(err, res, body) {
                if (res && res.statusCode === '200') {
                    var title = cheerio.load(body)('head title').text();
                    if (title.length) {
                        client.say(chan, title);
                    } else {
                        client.say(chan, "Merge request !" + mrId + ": " + url);
                    }
                }
            });
        }
    });
});