// twister_timeline.js
// 2013 Miguel Freitas
//
// Provides objects to keep track of timeline display state to request new posts efficiently.
//
// Currently is being used only for "home" timeline, but the list of users can be an arbitrary
// subset of users we follow. In other words: this objects may be used for displaying profiles
// of those users more efficiently than iterating through dht posts.


var _idTrackerMap = {};
var _idTrackerSpam = new idTrackerObj();
var _lastHaveMap = {};
var _refreshInProgress = false;
var _newPostsPending = [];
var _sendedPostIDs = [];
var timelineLoaded = false;

/* object to keep tracking of post ids for a given user, that is, which
 * posts have already been received, processed, shown + which ones to request.
 * modes of operation:
 * "latestFirstTime" this is the first time the timeline is obtained, we known
 *                   nothing about the last post ids. there will be no gap since
 *                   timeline is empty on screen.
 * "latest" this is used when we have a timeline on screen but we want to update
 *          it with the latest posts. since getposts rpc may limit the number of
 *          posts to receive, a gap may be created. that is, between the most
 *          recent post of the previous update and the lower id received by getposts.
 * "fillgap" this is used to fill the gap after "latest" was used.
 * "older"  this is used to scroll down the timeline, to older posts than are
 *          currently being shown on screen.
 */
function idTrackerObj()
{
    this.latest = -1;
    this.oldest = -1;
    this.gapHigh = -1;
    this.gapLow = -1;

    // getRequest method creates a single user item of getposts rpc list parameter
    this.getRequest = function (mode) {
        if( mode == 'latest' || mode == 'latestFirstTime' ) {
            this.gapHigh = -1;
            this.gapLow = this.latest;
            return { since_id: this.latest };
        } else if( mode == 'fillgap') {
            return { max_id: this.gapHigh-1, since_id: this.gapLow };
        } else if( mode == 'older') {
            return ( this.oldest >= 0 ) ? { max_id: this.oldest-1 } : {};
        } else {
           console.log("getRequest: unknown mode");
        }
    }

    // receiveId method notifies that a post was received (and possibly shown)
    this.receivedId = function (mode, id, shown){
        if( id > this.latest ) this.latest = id;
        if( shown ) {
            if( this.oldest < 0 || id < this.oldest ) this.oldest = id;
        }
        if( mode == 'latest' ||
            mode == 'latestFirstTime' ||
            mode == 'fillgap') {
            if( this.gapHigh < 0 || id < this.gapHigh )
                this.gapHigh = id;
        } else if( mode == 'older') {
            // no gaps: posts are already received in descending order
        } else {
           console.log("receivedId: unknown mode");
        }
    }
}

/* object to maintain a request state for several users.
 * each user is tracked by idTrackerObj in global _idTrackerMap.
 */
function requestObj(users, mode, count, getspam)
{
    this.users = users;
    this.mode = mode; // 'latest', 'latestFirstTime' or 'older'
    this.count = count;
    this.getspam = getspam;

    // getRequest method returns the list parameter expected by getposts rpc
    this.getRequest = function() {
        var req = [];
        if( this.mode == 'done')
            return req;
        if( this.getspam ) {
            return _idTrackerSpam.getRequest(this.mode);
        }
        for( var i = 0; i < this.users.length; i++ ) {
            var user = this.users[i];
            if( !(user in _idTrackerMap) )
                _idTrackerMap[user] = new idTrackerObj();
            var r = _idTrackerMap[user].getRequest(this.mode);
            r.username = user;
            req.push(r);
        }
        return req;
    }

    // receiveId method notifies that a post was received (and possibly shown)
    this.reportProcessedPost = function(user, id, shown) {
        if( this.getspam ) {
            _idTrackerSpam.receivedId(this.mode, id, shown);
        } else if( this.users.indexOf(user) >= 0 ) {
            _idTrackerMap[user].receivedId(this.mode, id, shown);
        }
    }

    // doneReportProcessing is called after an getposts response is processed
    // mode changing may require a new request (to fill gaps)
    this.doneReportProcessing = function(receivedCount) {
        if (receivedCount === this.count) {
            this.mode = 'done';
        } else {
            if (this.mode === 'latest' || this.mode === 'latestFirstTime') {
                this.mode = 'fillgap';
            } else if (this.mode === 'fillgap') {
                this.mode = 'older';
            } else if (this.mode === 'older')
                this.mode = 'done';
        }
        //console.log('we got '+receivedCount+' posts from requested '+this.count+', status of processing is "'+this.mode+'"');
    }
}

// json rpc with requestObj as parameter
function requestGetposts(req)
{
    var r = req.getRequest();
    if( !req.getspam ) {
        if( r.length ) {
            twisterRpc("getposts", [req.count,r],
                       function(req, posts) {processReceivedPosts(req, posts);}, req,
                       function(req, ret) {console.log("ajax error:" + ret);}, req);
        }
    } else {
        twisterRpc("getspamposts", [req.count,r.max_id?r.max_id:-1,r.since_id?r.since_id:-1],
                   function(req, posts) {processReceivedPosts(req, posts);}, req,
                   function(req, ret) {console.log("ajax error:" + ret);}, req);
    }
}

// callback to getposts rpc when updating the timeline
// process the received posts (adding them to screen) and do another
// request if needed
function processReceivedPosts(req, posts)
{
    //hiding posts can cause empty postboard, so we have to track the count...
    for( var i = 0; i < posts.length; i++ ) {
        if (willBeHidden(posts[i])) {
            posts.splice(i, 1);
            i--;
        }
    }
    showPosts(req, posts);
    req.doneReportProcessing(posts.length);

    //if the count of recieved posts less or equals to requested then...
    if (req.mode === 'done') {
        timelineLoaded = true;
        $.MAL.postboardLoaded();
        _refreshInProgress = false;
    } else {
        //we will request more older post...
        req.count -= posts.length;
        if (req.count > 0) {
            //console.log('we are requesting '+req.count+' more posts...');
            requestGetposts(req);
        } else {
            timelineLoaded = true;
            $.MAL.postboardLoaded();
            _refreshInProgress = false;
        }
    }
}

function showPosts(req, posts)
{
    var streamItemsParent = $.MAL.getStreamPostsParent();

    for( var i = 0; i < posts.length; i++ ) {
        if ( req.users.indexOf(posts[i]['userpost']['n']) > -1 ) {
            var post = posts[i];

            var streamPost = postToElem(post, "original", req.getspam);
            var timePost = post["userpost"]["time"];
            streamPost.attr("data-time",timePost);

            // post will only be shown if appended to the stream list
            var streamPostAppended = false;

            // insert the post in timeline ordered by (you guessed) time
            // FIXME: lame! searching everything everytime. please optimize!
            var streamItems = streamItemsParent.children();
            if( streamItems.length == 0) {
                // timeline is empty
                streamItemsParent.append( streamPost );
                streamPostAppended = true;
            } else {
                var j = 0;
                for( j = 0; j < streamItems.length; j++) {
                    var streamItem = streamItems.eq(j);
                    var timeItem = streamItem.attr("data-time");
                    if( timeItem == undefined ||
                        timePost > parseInt(timeItem) ) {
                        // this post in stream is older, so post must be inserted above
                        streamItem.before(streamPost);
                        streamPostAppended = true;
                        break;
                    }
                }
                if( j == streamItems.length ) {
                    // no older posts in stream, so post is to be inserted below
                    if( req.mode == "older" || req.mode == "latestFirstTime" ) {
                        // note: when filling gaps, the post must be discarded (not
                        // shown) since it can never be older than what we already
                        // have on timeline. this is a problem due to requesting from
                        // several users at the same time, as some older posts might
                        // be included to complete the <count> in getposts because
                        // other users may have already been excluded by since_id.
                        streamItemsParent.append( streamPost );
                        streamPostAppended = true;
                    }
                }
            }

            if( streamPostAppended ) {
                streamPost.show();
            }
            req.reportProcessedPost(post["userpost"]["n"],post["userpost"]["k"], streamPostAppended);
        }
    }
}

// request timeline update for a given list of users
function requestTimelineUpdate(mode, count, timelineUsers, getspam)
{
    //console.log(mode+' timeline update request: '+count+' posts for following users - '+timelineUsers);
    if( _refreshInProgress || !defaultScreenName)
        return;
    $.MAL.postboardLoading();
    _refreshInProgress = true;
    if( timelineUsers.length ) {
        var req = new requestObj(timelineUsers, mode, count, getspam);
        if (mode === 'pending') {
            req.mode = 'latest';
            showPosts(req, _newPostsPending);
            _newPostsPending = [];
            $.MAL.reportNewPosts(_newPostsPending.length);
            $.MAL.postboardLoaded();
            _refreshInProgress = false;
        } else {
            requestGetposts(req);
        }
    } else {
        console.log("requestTimelineUpdate: not following any users");
    }
}

// getlasthave is called every second to check if followed users have posted anything new
function requestLastHave() {
    twisterRpc("getlasthave", [defaultScreenName],
           function(req, ret) {processLastHave(ret);}, null,
           function(req, ret) {console.log("ajax error:" + ret);}, null);
}

// handle getlasthave response. the increase in lasthave cannot be assumed to
// produce new items for timeline since some posts might be directmessages (which
// won't be returned by getposts, normally).
function processLastHave(userHaves)
{
    var reqConfirmNewPosts = [];
    var newPostsLocal = 0;
    for( var user in userHaves ) {
        if( userHaves.hasOwnProperty(user) ) {
            // checks for _idTrackerMap as well. the reason is that getlasthave
            // returns all users we follow, but the current timeline might be
            // for just a single user.
            if( user in _lastHaveMap && user in _idTrackerMap) {
                if( userHaves[user] > _lastHaveMap[user] ) {
                    newPostsLocal += userHaves[user] - _lastHaveMap[user];
                    reqConfirmNewPosts.push( {username:user, since_id:_lastHaveMap[user]} );
                }
            }
            _lastHaveMap[user] = userHaves[user];

            if( user == defaultScreenName ) {
                if( lastPostId == undefined || userHaves[user] > lastPostId ) {
                    incLastPostId(userHaves[user]);
                }
            }
        }
    }

    // now do a getposts to confirm the number of new haves with are effectively new public posts
    if( newPostsLocal ) {
        twisterRpc("getposts", [newPostsLocal, reqConfirmNewPosts],
               function(expected, posts) {processNewPostsConfirmation(expected, posts);}, newPostsLocal,
               function(req, ret) {console.log("ajax error:" + ret);}, null);
    }
}

// callback for getposts to update the number of new pending posts not shown in timeline
function processNewPostsConfirmation(expected, posts)
{
    //console.log('we got '+posts.length+' posts from expected '+expected+' for confirmation');
    //console.log(posts);
    // we want to report about new posts that would be displayed
    var rnp = 0;
    // we want to display sended posts immediately
    var sendedPostsPending = [];
    for( var i = posts.length-1; i >= 0; i-- ) {
        if ( !willBeHidden(posts[i]) ) {
            if ( _sendedPostIDs.indexOf(posts[i]['userpost']['k']) > -1 ) {
                sendedPostsPending.push(posts[i]);
            } else {
                _newPostsPending.push(posts[i]);
                rnp++;
            }
        }
    }
    if ( rnp > 0 ) {
        $.MAL.reportNewPosts(_newPostsPending.length);
    }
    if ( sendedPostsPending.length > 0 ) {
        var req = new requestObj([defaultScreenName],'latest',sendedPostsPending.length,promotedPostsOnly);
        showPosts(req, sendedPostsPending);
    }

    if( posts.length < expected ) {
        // new DMs have probably been produced by users we follow.
        // check with getdirectmsgs
        requestDMsCount();
    }
}

function timelineChangedUser()
{
    _idTrackerMap = {};
    _idTrackerSpam = new idTrackerObj();
    _lastHaveMap = {};
    _refreshInProgress = false;
    _newPostsPending = [];
    _sendedPostIDs = [];
    timelineLoaded = false;
}

function willBeHidden(post){
    var msg = post['userpost']['msg'];
    var hidden = false;

    if (post['userpost']['n'] === defaultScreenName)
        return false;

    if ($.Options.getHideRepliesOpt() !== 'disable' &&
        /^\@/.test(msg) &&
        !(new RegExp('@' + defaultScreenName + '( |,|;|\\.|:|\\/|\\?|\\!|\\\\|\'|"|\\n|\\t|$)').test(msg)))
    {
            if ($.Options.getHideRepliesOpt() === 'only-me' ||
                ($.Options.getHideRepliesOpt() === 'following' &&
                 followingUsers.indexOf(msg.substring(1, msg.search(/ |,|;|\.|:|\/|\?|\!|\\|'|"|\n|\t|$/))) === -1 ))
            {
                hidden = true;
            }
    }

    if (typeof(post['userpost']['rt']) !== 'undefined' &&
        $.Options.getHideCloseRTsOpt() != 'disable' &&
        followingUsers.indexOf(post['userpost']['rt']['n']) > -1 &&
        parseInt(post['userpost']['time']) - parseInt(post['userpost']['rt']['time']) < $.Options.getHideCloseRTsHourOpt() * 3600)
    {
        if (hidden)
            return false;
        else
            return true;
    }

    return hidden;
}