var compose = (function () {

var exports = {};
var is_composing_message = false;
var faded_to;

function show(tabname, focus_area) {
    if (tabname === "stream") {
        $('#private-message').hide();
        $('#stream-message').show();
        $("#stream_toggle").addClass("active");
        $("#private_message_toggle").removeClass("active");
    } else {
        $('#private-message').show();
        $('#stream-message').hide();
        $("#stream_toggle").removeClass("active");
        $("#private_message_toggle").addClass("active");
    }
    $("#send-status").removeClass(status_classes).hide();
    $('#compose').css({visibility: "visible"});
    $("#new_message_content").trigger("autosize");
    $('.message_comp').slideDown(100, function () {
        // If the compose box is obscuring the currently selected message,
        // scroll up until the message is no longer occluded.
        if (current_msg_list.selected_id() === -1) {
            // If there's no selected message, there's no need to
            // scroll the compose box to avoid it.
            return;
        }
        var selected_row = current_msg_list.selected_row();
        var cover = selected_row.offset().top + selected_row.height()
            - $("#compose").offset().top;
        if (cover > 0) {
            disable_pointer_movement = true;
            // We use $('html, body') because you can't animate window.scrollTop
            // on Chrome (http://bugs.jquery.com/ticket/10419).
            $('html, body').animate({
                scrollTop: viewport.scrollTop() + cover + 5
            }, {
                complete: function () {
                    // The complete callback is actually called before the
                    // scrolling has completed, so we try to let scrolling
                    // finish before allowing pointer movements again or the
                    // pointer may still move.
                    setTimeout(function () {
                        disable_pointer_movement = false;
                    }, 50);
                }
            });
        }
    });
    focus_area.focus();
    focus_area.select();
    // Disable the notifications bar if it overlaps with the composebox
    notifications_bar.maybe_disable();
}

// In an attempt to decrease mixing, make the composebox's
// stream bar look like what you're replying to.
// (In particular, if there's a color associated with it,
//  have that color be reflected here too.)
exports.decorate_stream_bar = function (stream_name) {
    var color = subs.get_color(stream_name);
    $("#stream-message .message_header_stream")
        .css('background-color', color)
        .removeClass(subs.color_classes)
        .addClass(subs.get_color_class(color));
};

function neighbors(target_message) {
    var table = narrow.active() ? "zfilt" : "zhome";
    var message_tr = $(rows.get(target_message.id, table));
    var message_neighbors = $();

    // Being simplistic about this, the smallest message is 30 px high. This
    // gives you a screen's worth of fade on either side of the target message
    // message at worst.
    var num_neighbors = Math.floor(viewport.height() / 30);
    var candidates = $.merge(message_tr.prevAll(":not('.bookend_tr'):lt(" + num_neighbors + ")"),
                             message_tr.nextAll(":not('.bookend_tr'):lt(" + num_neighbors + ")"));

    $.each(candidates, function () {
        var row = $(this);
        if (row.hasClass("recipient_row")) {
            message_neighbors = message_neighbors.add(row);
        } else {
            message_neighbors = message_neighbors.add(row.children(".messagebox")[0]);
        }
    });

    return message_neighbors;
}

function neighbors_with_different_recipients(target_message) {
    return neighbors(target_message).filter(function (index) {
        if ($(this).hasClass("recipient_row")) {
            // This is a recipient_row.
            return !same_recipient(target_message, current_msg_list.get(rows.id($(this))));
        } else {
            // This is a messagebox.
            var row = $(this).parent("tr");
            return !same_recipient(target_message, current_msg_list.get(rows.id(row)));
        }
    });
}

function fade_around(reply_message) {
    faded_to = reply_message;
    var fade_class = narrow.active() ? "message_reply_fade_narrowed" : "message_reply_fade";

    neighbors_with_different_recipients(reply_message).addClass(fade_class);
    ui.disable_floating_recipient_bar();
}

exports.unfade_messages = function () {
    if (faded_to === undefined) {
        return;
    }

    var table = narrow.active() ? "zfilt" : "zhome";
    var fade_class = narrow.active() ? "message_reply_fade_narrowed" : "message_reply_fade";

    neighbors_with_different_recipients(faded_to).removeClass(fade_class);
    faded_to = undefined;
    ui.enable_floating_recipient_bar();
};

exports.start = function (msg_type, opts) {
    if (reload.is_in_progress()) {
        return;
    }

    compose.clear();

    opts = $.extend({ message_type:     msg_type,
                      stream:           '',
                      subject:          '',
                      private_message_recipient: ''
                    }, opts);

    compose.stream_name(opts.stream);
    compose.subject(opts.subject);
    compose.recipient(opts.private_message_recipient);
    // If the user opens the compose box, types some text, and then clicks on a
    // different stream/subject, we want to keep the text in the compose box
    if (opts.message !== undefined) {
        compose.message_content(opts.message);
    }

    ui.change_tab_to("#home");

    var focus_area;
    if (opts.stream && ! opts.subject) {
        focus_area = 'subject';
    } else if (opts.stream || opts.private_message_recipient) {
        focus_area = 'new_message_content';
    }

    if (msg_type === 'stream') {
        show('stream', $("#" + (focus_area || 'stream')));
    } else {
        show('private', $("#" + (focus_area || 'private_message_recipient')));
    }

    if (opts.replying_to_message !== undefined) {
        if (exports.composing() && (faded_to !== opts.replying_to_message)) {
            // Already faded to another message. First unfade everything.
            exports.unfade_messages();
        }
        fade_around(opts.replying_to_message);
    }

    is_composing_message = msg_type;
    exports.decorate_stream_bar(opts.stream);
    $(document).trigger($.Event('compose_started.zephyr', opts));
};

exports.cancel = function () {
    compose.hide();
    is_composing_message = false;
    $(document).trigger($.Event('compose_canceled.zephyr'));
};

function compose_error(error_text, bad_input) {
    $('#send-status').removeClass(status_classes)
               .addClass('alert-error')
               .stop(true).fadeTo(0, 1);
    $('#error-msg').html(error_text);
    $("#compose-send-button").removeAttr('disabled');
    bad_input.focus().select();
}

var send_options;

function send_message() {
    var send_status = $('#send-status');

    // TODO: this should be collapsed with the code in composebox_typeahead.js
    var recipients = compose.recipient().split(/\s*[,;]\s*/);

    var request = {client: 'website',
                   type:        compose.composing(),
                   subject:     compose.subject(),
                   content:     compose.message_content()};
    if (request.type === "private") {
        request.to = JSON.stringify(recipients);
    } else {
        request.to = JSON.stringify([compose.stream_name()]);
    }

    if (tutorial.is_running()) {
        // We make a new copy of the request object for the tutorial so that we
        // don't mess up the request we're actually sending to the server
        var tutorial_copy_of_message = $.extend({}, request, {to: compose.stream_name()});
        if (request.type === "private") {
            $.extend(tutorial_copy_of_message, {to: recipients});
        }
        tutorial.message_was_sent(tutorial_copy_of_message);
    }

    $.ajax({
        dataType: 'json', // This seems to be ignored. We still get back an xhr.
        url: '/json/send_message',
        type: 'POST',
        data: request,
        success: function (resp, statusText, xhr) {
            compose.clear();
            send_status.hide();
            is_composing_message = false;
            compose.hide();
            $("#compose-send-button").removeAttr('disabled');
        },
        error: function (xhr, error_type) {
            if (error_type !== 'timeout' && reload.is_pending()) {
                // The error might be due to the server changing
                reload.initiate({immediate: true, send_after_reload: true});
                return;
            }
            var response = "Error sending message";
            if (xhr.status.toString().charAt(0) === "4") {
                // Only display the error response for 4XX, where we've crafted
                // a nice response.
                response += ": " + $.parseJSON(xhr.responseText).msg;
            }
            compose_error(response, $('#new_message_content'));
        }
    });

    send_status.hide();
}

exports.finish = function () {
    if (! compose.validate()) {
        return false;
    }
    send_message();
    // TODO: Do we want to fire the event even if the send failed due
    // to a server-side error?
    $(document).trigger($.Event('compose_finished.zephyr'));
    return true;
};

$(function () {
    $("#compose form").on("submit", function (e) {
       e.preventDefault();
       compose.finish();
    });
});

exports.hide = function () {
    $('input, textarea, button').blur();
    $('.message_comp').slideUp(100,
                              function() { $('#compose').css({visibility: "hidden"});});
    notifications_bar.enable();
    exports.unfade_messages();
};

exports.clear = function () {
    $("#compose").find('input[type=text], textarea').val('');
};

// Set the mode of a compose already in progress.
// Does not clear the input fields.
exports.set_mode = function (mode) {
    ui.change_tab_to('#home');
    if (!is_composing_message) {
        exports.start(mode);
    }
    if (mode === 'private') {
        show('private', $("#private_message_recipient"));
        is_composing_message = "private";
    } else {
        show('stream', $("#stream"));
        is_composing_message = "stream";
    }
};

exports.composing = function () {
    return is_composing_message;
};

function get_or_set(fieldname, keep_outside_whitespace) {
    // We can't hoist the assignment of 'elem' out of this lambda,
    // because the DOM element might not exist yet when get_or_set
    // is called.
    return function (newval) {
        var elem = $('#'+fieldname);
        var oldval = elem.val();
        if (newval !== undefined) {
            elem.val(newval);
        }
        return keep_outside_whitespace ? oldval : $.trim(oldval);
    };
}

exports.stream_name     = get_or_set('stream');
exports.subject         = get_or_set('subject');
exports.message_content = get_or_set('new_message_content', true);
exports.recipient       = get_or_set('private_message_recipient');

// *Synchronously* check if a stream exists.
exports.check_stream_existence = function (stream_name) {
    var result = "error";
    var error_xhr = "";
    $.ajax({
        type: "POST",
        url: "/json/subscriptions/exists",
        data: {'stream': stream_name},
        async: false,
        success: function (data) {
            if (!data.exists) {
                result = "does-not-exist";
            } else if (data.subscribed) {
                result = "subscribed";
            } else {
                result = "not-subscribed";
            }
        },
        error: function (xhr) {
            result = "error";
            error_xhr = xhr;
        }
    });
    return [result, error_xhr];
};


// Checks if a stream exists. If not, displays an error and returns
// false.
function check_stream_for_send(stream_name) {
    var stream_check = exports.check_stream_existence(stream_name);
    var result = stream_check[0];
    var xhr = stream_check[1];

    if (result === "error") {
        ui.report_error("Error checking subscription", xhr, $("#home-error"));
        $("#stream").focus();
        $("#compose-send-button").removeAttr('disabled');
    }

    return result;
}

function validate_stream_message() {
    var stream_name = exports.stream_name();
    if (stream_name === "") {
        compose_error("Please specify a stream", $("#stream"));
        return false;
    }

    if (exports.subject() === "") {
        compose_error("Please specify a subject", $("#subject"));
        return false;
    }

    var response;

    if (!subs.have(stream_name)) {
        switch(check_stream_for_send(stream_name)) {
        case "does-not-exist":
            response = "<p>The stream <b>" +
                Handlebars.Utils.escapeExpression(stream_name) + "</b> does not exist.</p>" +
                "<p>Manage your subscriptions <a href='#subscriptions'>on your Streams page</a>.</p>";
            compose_error(response, $('#stream'));
            return false;
        case "error":
            return false;
        case "subscribed":
            // You're actually subscribed to the stream, but this
            // browser window doesn't know it.
            return true;
        case "not-subscribed":
            response = "<p>You're not subscribed to the stream <b>" +
                Handlebars.Utils.escapeExpression(stream_name) + "</b>.</p>" +
                "<p>Manage your subscriptions <a href='#subscriptions'>on your Streams page</a>.</p>";
            compose_error(response, $('#stream'));
            return false;
        }
    }

    return true;
}

function validate_private_message() {
    if (exports.recipient() === "") {
        compose_error("Please specify at least one recipient", $("#private_message_recipient"));
        return false;
    }

    return true;
}

exports.validate = function () {
    $("#compose-send-button").attr('disabled', 'disabled').blur();

    if (exports.message_content() === "") {
        compose_error("You have nothing to send!", $("#new_message_content"));
        return false;
    }

    if (exports.composing() === 'private') {
        return validate_private_message();
    } else {
        return validate_stream_message();
    }
};

$(function () {
    $("#new_message_content").autosize();
});

return exports;

}());