var user = [];
var timelines = [];
var activeTimeline = [];
var entries = [];

var newEntryBar;
var moreEntriesbar;

var currentEntryOffset = 0;
var loadLength = 20;

/* Setup after the document is ready for manipulation. */
$(document).ready(function(){

    // looked up once and remembered
    newEntryBar = $("#new-entry");
    moreEntriesBar = $("#more-entries");

    // wire the login dialog using jQuery UI
    $("#login-dialog").dialog({
        autoOpen: false,
        height: 300,
        width: 300,
        modal: true,
        buttons: { Login: function(){login()} }
    });

    // TODO: add a hook to AJAX requests to check for 401 unauth
    // and re-display the login dialog.

    // try to load user information for an authenticated user
    $.ajax({
        url: "/ts_api/users/",
        type: "GET",

        error: function(jqXHR, textStatus, error) {
            // assume there is no authenticated user, show login dialog
            $("#login-dialog").dialog("open"); },

        success: function(data, textStatus, jqXHR) {
            // load the user information
            loadUser(data.user.username); }});

})

/* Read the user's credentials from the login form and perform
 *  an AJAX request to the API to set the session cookie.  */
function login() {
    // lookup the login dialog elements
    var name = $("#login-name");
    var pwd = $("#login-password");

    // call the API via AJAX
    $.ajax({
        url: "/ts_api/login",
        processData: false,
        data: JSON.stringify({username: name.val(), password: pwd.val()}),
        type: "POST",

        error: function(jqXHR, textStatus, error) {
            // assuming bad credentials (possible server error or bad request,
            // we should check that, FIXME
            var tips = $(".validate-tips");
            tips.text("Incorrect username/password combination.");
            tips.addClass("ui-state-error");
            tips.slideDown();
        },

        success: function(data, textStatus, jqXHR) {
            // load the user information and hide the login dialog
            loadUser(name.val());
            $("#login-dialog").dialog("close");
        }});
}

/* End the current user session and expire any session credentials we
 * have aquired.  */
function logout(event) {
    alert("TODO: log user out via AJAX.");
    // TODO: wipe username, timeline, entry variables and displays
    event.preventDefault();
}

/* Load and display the user's information and timelines.  */
function loadUser(username) {

    // call the user_summary API function
    $.ajax({
        url: "/ts_api/app/user_summary/" + username,
        type: "GET",

        success: function(data, textStatus, jqXHR) {
            // set the user variable
            user = data.user;

            // set the timelines variable
            timelines = data.timelines;

            // update the user id display
            $("#fullname").text(user.name);
            $("#username").text("- " + user.username);

            // pre-populate the editable user-info fields
            $("#fullname-input").val(user.name);
            $("#email-input").val(user.email);

            // set the active timeline to the first in the list
            // TODO: implement a mechanism to remember the last used timeline
            // on the server side and respond to that here.
            activeTimeline = timelines[0];

            // update the timeline display
            $("#timeline-name").text(activeTimeline.timeline_id + " |");
            $("#timeline-desc").text(activeTimeline.description);
            $("#timeline-desc-input").val(activeTimeline.description);

            // TODO: populate the drop-down list for the available timeline
            // choices

            // load the entries for this timeline
            loadEntries(user, activeTimeline, "new")
        },

        error: function(jqXHR, textStatus, error) {
            // TODO
            alert("TODO: handle error for user load.")
            alert(jqXHR.responseText)
        }
    });
}

/* Read entries for a timeline.  */
function loadEntries(user, timeline, order) {

    // call the API list_entries function via AJAX
    $.ajax({
        url: "/ts_api/entries/" + user.username + "/"
            + timeline.timeline_id + "?order=asc&start="
            + currentEntryOffset + "&length=" + loadLength,
        type: "GET",

        success: function(data, textStatus, jqXHR) {
            entries = data.entries;

            if (order == "new") {
                // reverse the list so that the oldest are first
                entries.reverse()
                
                // push the entries onto the page
                displayNewerEntries(entries)
            } else {
                displayOlderEntries(entries)
            }

            // update our current offset
            currentEntryOffset += loadLength;
        },

        error: function(jqXHR, textStatus, error) {
            alert(jqXHR.responseText);
        }
    });
}

/* Push the entries onto the top of the entry display. This function assumes
 * that the entries are sorted by id, ascending (0, 1, 2). Each new entry goes
 * on top, pushing down all existing entries. So the first entry in the
 * argument list ends up at the bottom of the new entries. */
function displayNewerEntries(entries) {

    // for each entry
    _.each(entries, function(entry) {

        // remove the existing top-entry designation
        $(".top-entry").removeClass("top-entry");

        // create the new entry from the entry template (see ICanHas.js)
        var entryElem = ich.entry(entry);

        // mark the new entry as the current top-entry
        entryElem.addClass("top-entry");

        // push the entry on after the new-entry bar (on top of existing
        // entries).
        newEntryBar.after(entryElem);

        // TODO: animate? If so, may need to pause after each to allow
        // some animation to take place. Going for a continuous push-down
        // stack effect.
    });
}

/* Push the entries onto the bottom of the entry display. The function assumes
 * that the entries are sorted by id, descending (2, 1, 0). Each new entry goes
 * at the bottom of the stack of entries, extending the stack downwards. So the
 * last entry in the list is at the very bottom of the stack. */
function displayOlderEntries(entries) {

    // for each entry
    _.each(entries, function(entry) {

        // create the new entry from the template (ICanHas.js)
        var entryElem = ich.entry(entry);

        // place the entry on top of the bottom of the page
        moreEntriesBar.before(entryElem);

        // perhaps animate, see comments at the end of displayNewerEntries()
    });
}

/* Update the user information based on the editable user-info panel. */
function updateUser(event) {
    alert("TODO: update user via AJAX.");
    event.preventDefault();
}

/* Show the change timeline menu. */
function showTimelineMenu(event) {
    alert("TODO: show other timelines via a popup menu");
    event.preventDefault();
}

/* Update the timeline details based on the editable timeline-info panel. */
function updateTimeline(event) {
    var desc = $("#timeline-desc-input").val();

    $.ajax({url: "/ts_api/timelines/" + user.username
                                + "/" + activeTimeline.timeline_id,
        type: "POST",
        data: JSON.stringify({desc: desc, created: activeTimeline.created}),

        error: function(jqXHR, textStatus, error) {
            // TODO: better error handling
            alert("Error updating timeline: \n" + jqXHR.responseText); },

        success: function(data, testStatus, jqXHR) {
            // TODO: check for appropriate data.status value

            // update display
            $("#timeline-desc").text(data.timeline.description);
        }});

    event.preventDefault();
}

/* Create a new entry based on the user's input in the new-entry panel. */
function newEntry(event) {
    
    var mark = $("#new-entry-input").val();
    var notes = $("#new-notes-input").val();
    var timestamp = getUTCTimestamp();  // timestamp is handled on client.
    // This is important. It means that the timestamps are completely in the
    // hands of the user. Timestamps from this service can not be considered
    // secure. This service is not a punch-card, but a time-tracker, voluntary
    // and editable by the user.

    var payload = JSON.stringify(
        { mark: mark, notes: notes, timestamp: timestamp });

    $.ajax({url: "/ts_api/entries/" + user.username
                              + "/" + activeTimeline.timeline_id,
        type: "PUT",
        data: payload,

        error: function(jqXHR, textStatus, error) {
            // TODO: better error handling.
            alert("Error creating entry: \n" + jqXHR.responseText); },

        success: function(data, textStatus, jqXHR) {
            // TODO: check that data.status == "ok"

            // grab the entry data
            var newEntry = data.entry;

            // push the entry on top of the stack
            displayNewerEntries([newEntry]);

            // clear the input
            $("#new-entry-input").val("");
            $("#new-notes-input").val("");
        }});

    event.preventDefault();
}

function toggleEditEntry(event, entryId) {
    $("#entry-" + entryId + " .entry-display").toggle();
    $("#entry-" + entryId + " .entry-edit").toggle();
    event.preventDefault();
}

function updateEntry(event, entryId) {

    var mark = $("#entry-" + entryId + "-mark-input").val();
    var notes = $("#entry-" + entryId + "-notes-input").val();
    var timestamp = getUTCTimestamp(); // TODO: define and read from input element

    var payload = JSON.stringify(
        { mark: mark, notes: notes, timestamp: timestamp });

    $.ajax({url: "/ts_api/entries/" + user.username
                              + "/" + activeTimeline.timeline_id
                              + "/" + entryId,
        type: "POST",
        data: payload,

        error: function(jqXHR, textStatus, error) {
            // TODO: error handling
            alert("Error updating entry: \n" + jqXHR.responseText); },

        success: function(data, textStatus, jqXHR) {
            // TODO: check that data.status is appropriate

            // update the entry display
            $("#entry-" + entryId + " .entry-mark").text(data.entry.mark);
            $("#entry-" + entryId + " .entry-notes").text(data.entry.notes);
        }});

    toggleEditEntry(event, entryId);
}

/* Delete an entry. */
function deleteEntry(event, entryId) {
    $.ajax({url: "/ts_api/entries/" + user.username
                              + "/" + activeTimeline.timeline_id
                              + "/" + entryId,
        type: "DELETE",
        
        error: function(jqXHR, textStatus, error) {
            // TODO: error handling
            alert("Error updating entry: \n" + jqXHR.responseText); },

        success: function(data, textStatus, jqXHR) {
            $("#entry-" + entryId).slideUp('slow',
                function()  {$("#entry-" + entryId).remove(); });
        }});

    event.preventDefault();
}

/* Generate a UTC timestamp string in ISO format.
 * Javascript 1.8.5 has Date.toJSON(), which is equivalent to this function,
 * but is only supported in Firefox 4. */
function getUTCTimestamp() {
    var d = new Date();

    function pad(n){return n<10 ? '0'+n : n}

    return d.getUTCFullYear()+'-'
        + pad(d.getUTCMonth()+1)+'-'
        + pad(d.getUTCDate())+'T'
        + pad(d.getUTCHours())+':'
        + pad(d.getUTCMinutes())+':'
        + pad(d.getUTCSeconds())+'Z';
}