var emoji_picker = (function () {

var exports = {};

// The functionalities for reacting to a message with an emoji
// and composing a message with an emoji share a single widget,
// implemented as the emoji_popover.
var current_message_emoji_popover_elem;
var default_emoji_order = {};
// Saves an array of the complete emoji list in default order.
var complete_emoji_list;

function promote_popular(a, b) {
    function rank(name) {
        switch (name) {
            case '+1': return 1;
            case 'tada': return 2;
            case 'simple_smile': return 3;
            case 'laughing': return 4;
            case '100': return 5;
            default: return 999;
        }
    }

    var diff = rank(a.name) - rank(b.name);

    if (diff !== 0) {
        return diff;
    }

    return util.strcmp(a.name, b.name);
}

function compute_placement(elt) {
    var approx_popover_height = 400;
    var approx_popover_width = 400;
    var distance_from_bottom = message_viewport.height() - elt.offset().top;
    var distance_from_right = message_viewport.width() - elt.offset().left;
    var will_extend_beyond_bottom_of_viewport = distance_from_bottom < approx_popover_height;
    var will_extend_beyond_top_of_viewport = elt.offset().top < approx_popover_height;
    var will_extend_beyond_left_of_viewport = elt.offset().left < (approx_popover_width / 2);
    var will_extend_beyond_right_of_viewport = distance_from_right < (approx_popover_width / 2);
    var placement = 'bottom';
    if (will_extend_beyond_bottom_of_viewport && !will_extend_beyond_top_of_viewport) {
        placement = 'top';
    }
    if (will_extend_beyond_right_of_viewport && !will_extend_beyond_left_of_viewport) {
        placement = 'left';
    }
    if (will_extend_beyond_left_of_viewport && !will_extend_beyond_right_of_viewport) {
        placement = 'right';
    }
    return placement;
}

function generate_emoji_picker_content(id) {
    var emojis = _.clone(emoji.emojis_name_to_css_class);

    var realm_emojis = emoji.realm_emojis;
    _.each(realm_emojis, function (realm_emoji, realm_emoji_name) {
        emojis[realm_emoji_name] = {
            name: realm_emoji_name,
            is_realm_emoji: true,
            url: realm_emoji.emoji_url,
        };
    });

    // Reacting to a specific message
    if (id !== undefined) {
        var emojis_used = reactions.get_emojis_used_by_user_for_message_id(id);
        _.each(emojis_used, function (emoji_name) {
            emojis[emoji_name] = {
                name: emoji_name,
                has_reacted: true,
                css_class: emoji.emojis_name_to_css_class[emoji_name],
                is_realm_emoji: emojis[emoji_name].is_realm_emoji,
                url: emojis[emoji_name].url,
            };
        });
    }

    var emoji_recs = _.map(emojis, function (val, emoji_name) {
        if (val.name) {
            return val;
        }

        return {
            name: emoji_name,
            css_class: emoji.emojis_name_to_css_class[emoji_name],
            has_reacted: false,
            is_realm_emoji: false,
        };
    });

    var args = {
        message_id: id,
        emojis: emoji_recs.sort(promote_popular),
    };

    for (var i = 1; i <= emoji_recs.length; i += 1) {
        default_emoji_order[emoji_recs[i-1].name] = i;
    }

    return templates.render('emoji_popover_content', args);
}

exports.toggle_emoji_popover = function (element, id) {
    var last_popover_elem = current_message_emoji_popover_elem;
    popovers.hide_all();
    if (last_popover_elem !== undefined
        && last_popover_elem.get()[0] === element) {
        // We want it to be the case that a user can dismiss a popover
        // by clicking on the same element that caused the popover.
        return;
    }

    $(element).closest('.message_row').toggleClass('has_popover has_emoji_popover');
    var elt = $(element);
    if (id !== undefined) {
        current_msg_list.select_id(id);
    }

    if (elt.data('popover') === undefined) {
        elt.prop('title', '');
        elt.popover({
            placement: compute_placement(elt),
            title:     "",
            content:   generate_emoji_picker_content(id),
            trigger:   "manual",
        });
        elt.popover("show");
        elt.prop('title', 'Add reaction...');
        $('.emoji-popover-filter').focus();
        $(".emoji-popover-emoji-map").perfectScrollbar({
            suppressScrollX: true,
            useKeyboard: false,
            // Picked so that each mousewheel bump moves 1 emoji down.
            wheelSpeed: 0.68,
        });
        current_message_emoji_popover_elem = elt;
        exports.render_emoji_show_list();
        complete_emoji_list = $('.emoji-popover-emoji').toArray();
    }
};

exports.reactions_popped = function () {
    return current_message_emoji_popover_elem !== undefined;
};

exports.hide_emoji_popover = function () {
    $('.has_popover').removeClass('has_popover has_emoji_popover');
    if (exports.reactions_popped()) {
        $(".emoji-popover-emoji-map").perfectScrollbar("destroy");
        current_message_emoji_popover_elem.popover("destroy");
        current_message_emoji_popover_elem = undefined;
    }
};

function get_selected_emoji() {
    return $(".emoji-popover-emoji").filter(":focus")[0];
}

var emoji_show_list = []; // local emoji_show_list

exports.render_emoji_show_list = function () {
    var emoji_list = $(".emoji-popover-emoji");
    emoji_show_list = emoji_list.filter(function () {
        return $(this).css('display') === "block";
    }).toArray();
};

// This function sets the order_no to each of the emojis visible in
// the emoji_picker.  The emojis are set with either the default
// order_no (case: empty search string) or the order_no as per the
// sorted order obtained w.r.t the search string.
function set_emoji_order(emoji_list, is_set_default) {
    var order_no;
    // To get the order_no as per the sorted order.
    var get_order = function (i) { return i.toString(); };
    if (is_set_default) { // To get default order_no.
        get_order = function (i) {
            return default_emoji_order[$(emoji_list[i-1]).attr('title')];
        };
    }
    for (var i = 1; i <= emoji_list.length; i += 1) {
        order_no = get_order(i); // Gets the respective order_no.
        $(emoji_list[i-1]).css('order', order_no);
    }
}

// This function on top of the default ordering of the emojis, sorts
// and sets the order_no for the emojis based on the query string
// (search string).
function order_emoji_show_list(emoji_list, query) {
    // Sets the default order_no for the emoji.  This is necessary to
    // preserve the default ordering of emoji, which gets changed
    // based on the query string.
    set_emoji_order(emoji_list, true);
    if (query !== '') {
        // Sorts the default emoji order w.r.t the query string.
        var result = util.prefix_sort(query, emoji_list,
            function (x) { return $(x).attr('title'); });
        emoji_list = result.matches.concat(result.rest);
        // Sets the order_no as per the sorted order.
        set_emoji_order(emoji_list, false);
    }
    return emoji_list;
}

function filter_emojis() {
    var elt = $(".emoji-popover-filter").expectOne();
    var search_term = elt.val().trim().toLowerCase();
    var emoji_list = $(".emoji-popover-emoji");
    if (search_term !== '') {
        emoji_show_list = [];
        for (var i = 0; i < emoji_list.length; i += 1) {
            if (emoji_list[i].title.indexOf(search_term) === -1) {
                emoji_list[i].classList.add("hide");
            } else {
                emoji_list[i].classList.remove("hide");
                emoji_show_list.push(emoji_list[i]);
            }
        }
    } else {
        emoji_list.removeClass("hide");
        // Direct assignment to optimize and render the complete list emoji faster.
        emoji_show_list = complete_emoji_list;
    }
    $('.emoji-popover-emoji-map').perfectScrollbar('update');
    emoji_show_list = order_emoji_show_list(emoji_show_list, search_term);
}

function get_emoji_at_index(index) {
    if (index >= 0 && index < emoji_show_list.length) {
        return emoji_show_list[index];
    }
}

function find_index_for_emoji(emoji) {
    return emoji_show_list.findIndex(function (reaction) {
       return emoji === reaction;
    });
}

function maybe_select_emoji(e) {
    if (e.keyCode === 13) { // enter key
        e.preventDefault();
        var first_emoji = get_emoji_at_index(0);
        if (first_emoji) {
            if (emoji_picker.is_composition(first_emoji)) {
                first_emoji.click();
            } else {
                reactions.toggle_emoji_reaction(current_msg_list.selected_id(), first_emoji.title);
            }
        }
    }
}

$(document).on('click', '.emoji-popover-emoji.reaction', function () {
    // When an emoji is clicked in the popover,
    // if the user has reacted to this message with this emoji
    // the reaction is removed
    // otherwise, the reaction is added
    var emoji_name = this.title;
    var message_id = $(this).parent().attr('data-message-id');

    var message = message_store.get(message_id);
    if (!message) {
        blueslip.error('reactions: Bad message id: ' + message_id);
        return;
    }

    if (reactions.current_user_has_reacted_to_emoji(message, emoji_name)) {
        $(this).removeClass('reacted');
    }
    reactions.toggle_emoji_reaction(message_id, emoji_name);
});

exports.toggle_selected_emoji = function () {
    // Toggle the currently selected emoji.
    var message_id = current_msg_list.selected_id();

    var message = message_store.get(message_id);

    if (!message) {
        blueslip.error('reactions: Bad message id: ' + message_id);
        return;
    }

    var selected_emoji = get_selected_emoji();

    if (selected_emoji === undefined) {
        return;
    }

    var emoji_name = selected_emoji.title;

    reactions.toggle_emoji_reaction(message_id, emoji_name);
};

exports.navigate = function (e, event_name) {
    var first_emoji = get_emoji_at_index(0);
    var selected_emoji = get_selected_emoji();
    var selected_index = find_index_for_emoji(selected_emoji);

    // special cases
    if (event_name === 'down_arrow') {
        if ($('.emoji-popover-filter').is(':focus') && first_emoji) { // move down into emoji map
            $(first_emoji).focus();
        }
    } else if (event_name === 'up_arrow') {
        if (selected_emoji && selected_index < 6) {
            // In this case, we're move up into the reaction filter
            // rows.  Here, we override the default browser behavior,
            // which in Firefox is good (preserving the cursor
            // position) and in Chrome is bad (cursor goes to
            // beginning) with something reasonable and consistent
            // (cursor goes to the end of the filter string).
            $('.emoji-popover-filter').focus().caret(Infinity);
            return true;
        }
    }

    if (selected_emoji === undefined) {
        return false;
    }
    var next_index;
    switch (event_name) {
        case 'down_arrow':
            next_index = selected_index + 6;
            break;
        case 'up_arrow':
            next_index = selected_index - 6;
            break;
        case 'left_arrow':
            next_index = selected_index - 1;
            break;
        case 'right_arrow':
            next_index = selected_index + 1;
            break;
    }
    var next_emoji = get_emoji_at_index(next_index);
    if (next_emoji) {
        $(next_emoji).focus();
        return true;
    }
    return false;
};

exports.register_click_handlers = function () {
    $(document).on('click', '.emoji-popover-emoji.composition', function (e) {
        var emoji_text = ':' + this.title + ':';
        var textarea = $("#new_message_content");
        textarea.caret(emoji_text);
        textarea.focus();
        e.stopPropagation();
        emoji_picker.hide_emoji_popover();
    });

    $("#compose").on("click", "#emoji_map", function (e) {
        e.preventDefault();
        e.stopPropagation();
        emoji_picker.toggle_emoji_popover(this);
    });

    $("#main_div").on("click", ".reactions_hover, .reaction_button", function (e) {
        var row = $(this).closest(".message_row");
        e.stopPropagation();
        emoji_picker.toggle_emoji_popover(this, rows.id(row));
    });

    $("body").on("click", ".actions_popover .reaction_button", function (e) {
        var msgid = $(e.currentTarget).data('message-id');
        e.preventDefault();
        e.stopPropagation();
        // HACK: Because we need the popover to be based off an
        // element that definitely exists in the page even if the
        // message wasn't sent by us and thus the .reaction_hover
        // element is not present, we use the message's
        // .icon-vector-chevron-down element as the base for the popover.
        emoji_picker.toggle_emoji_popover($(".selected_message .icon-vector-chevron-down")[0], msgid);
    });

    $(document).on('input', '.emoji-popover-filter', filter_emojis);
    $(document).on('keydown', '.emoji-popover-filter', maybe_select_emoji);

};

exports.is_composition = function (emoji) {
    return emoji.classList.contains('composition');
};

return exports;

}());

if (typeof module !== 'undefined') {
    module.exports = emoji_picker;
}