// Copyright (c) Jupyter Development Team.
// Distributed under the terms of the Modified BSD License.

define([
    'jquery',
    'base/js/utils',
    'base/js/i18n',
    'base/js/dialog',
    'underscore'
], function($, utils, i18n, dialog, _) {
    "use strict";

    var platform = utils.platform;

    var QuickHelp = function (options) {
        /**
         * Constructor
         *
         * Parameters:
         *  options: dictionary
         *      Dictionary of keyword arguments.
         *          events: $(Events) instance
         *          keyboard_manager: KeyboardManager instance
         *          notebook: Notebook instance
         */
        this.keyboard_manager = options.keyboard_manager;
        this.notebook = options.notebook;
        this.keyboard_manager.quick_help = this;
        this.events = options.events;
    };

    var cmd_ctrl = 'Ctrl-';
    var platform_specific;

    if (platform === 'MacOS') {
        // Mac OS X specific
        cmd_ctrl = 'Cmd-';
        platform_specific = [
            { shortcut: "Cmd-Up", help:i18n.msg._("go to cell start") },
            { shortcut: "Cmd-Down", help:i18n.msg._("go to cell end") },
            { shortcut: "Alt-Left", help:i18n.msg._("go one word left") },
            { shortcut: "Alt-Right", help:i18n.msg._("go one word right") },
            { shortcut: "Alt-Backspace", help:i18n.msg._("delete word before") },
            { shortcut: "Alt-Delete", help:i18n.msg._("delete word after") },
            { shortcut: "Cmd-Shift-z", help:i18n.msg._("redo") },
            { shortcut: "Cmd-Shift-u", help:i18n.msg._("redo selection") },
            { shortcut: "Ctrl-k", help:i18n.msg._("emacs-style line kill") },
            { shortcut: "Cmd-Backspace", help:i18n.msg._("delete line left of cursor") },
            { shortcut: "Cmd-Delete", help:i18n.msg._("delete line right of cursor") }
        ];
    } else {
        // PC specific
        platform_specific = [
            { shortcut: "Ctrl-Home", help:i18n.msg._("go to cell start") },
            { shortcut: "Ctrl-Up", help:i18n.msg._("go to cell start") },
            { shortcut: "Ctrl-End", help:i18n.msg._("go to cell end") },
            { shortcut: "Ctrl-Down", help:i18n.msg._("go to cell end") },
            { shortcut: "Ctrl-Left", help:i18n.msg._("go one word left") },
            { shortcut: "Ctrl-Right", help:i18n.msg._("go one word right") },
            { shortcut: "Ctrl-Backspace", help:i18n.msg._("delete word before")},
            { shortcut: "Ctrl-Delete", help:i18n.msg._("delete word after")},
            { shortcut: "Ctrl-y", help:i18n.msg._("redo")},
            { shortcut: "Alt-u", help:i18n.msg._("redo selection") }
        ];
    }

    var cm_shortcuts = [
        { shortcut:"Tab", help:i18n.msg._("code completion or indent") },
        { shortcut:"Shift-Tab", help:i18n.msg._("tooltip") },
        { shortcut: cmd_ctrl + "]", help:i18n.msg._("indent") },
        { shortcut: cmd_ctrl + "[", help:i18n.msg._("dedent") },
        { shortcut: cmd_ctrl + "a", help:i18n.msg._("select all") },
        { shortcut: cmd_ctrl + "z", help:i18n.msg._("undo") },
        { shortcut: cmd_ctrl + "/", help:i18n.msg._("comment") },
        { shortcut: cmd_ctrl + "d", help:i18n.msg._("delete whole line") },
        { shortcut: cmd_ctrl + "u", help:i18n.msg._("undo selection") },
        { shortcut: "Insert", help:i18n.msg._("toggle overwrite flag") }
    ].concat( platform_specific );

    var mac_humanize_map = {
        // all these are unicode, will probably display badly on anything except macs.
        // these are the standard symbol that are used in MacOS native menus
        // cf https://apple.stackexchange.com/questions/55727/
        // for htmlentities and/or unicode value
        'cmd':'⌘',
        'shift':'⇧',
        'alt':'⌥',
        'up':'↑',
        'down':'↓',
        'left':'←',
        'right':'→',
        'eject':'⏏',
        'tab':'⇥',
        'backtab':'⇤',
        'capslock':'⇪',
        'esc':'esc',
        'ctrl':'⌃',
        'enter':'↩',
        'pageup':'⇞',
        'pagedown':'⇟',
        'home':'↖',
        'end':'↘',
        'altenter':'⌤',
        'space':'␣',
        'delete':'⌦',
        'backspace':'⌫',
        'apple':'',
    };

    var default_humanize_map = {
        'shift':i18n.msg._('Shift'),
        'alt':i18n.msg._('Alt'),
        'up':i18n.msg._('Up'),
        'down':i18n.msg._('Down'),
        'left':i18n.msg._('Left'),
        'right':i18n.msg._('Right'),
        'tab':i18n.msg._('Tab'),
        'capslock':i18n.msg._('Caps Lock'),
        'esc':i18n.msg._('Esc'),
        'ctrl':i18n.msg._('Ctrl'),
        'enter':i18n.msg._('Enter'),
        'pageup':i18n.msg._('Page Up'),
        'pagedown':i18n.msg._('Page Down'),
        'home':i18n.msg._('Home'),
        'end':i18n.msg._('End'),
        'space':i18n.msg._('Space'),
        'backspace':i18n.msg._('Backspace'),
        '-':i18n.msg._('Minus')
        };

    var humanize_map;

    if (platform === 'MacOS'){
        humanize_map = mac_humanize_map;
    } else {
        humanize_map = default_humanize_map;
    }

    var special_case = { pageup: i18n.msg._("PageUp"), pagedown: i18n.msg._("Page Down") };

    function humanize_key(key){
        if (key.length === 1){
            return key.toUpperCase();
        }

        key = humanize_map[key.toLowerCase()]||key;

        if (key.indexOf(',') === -1){
            return  ( special_case[key] ? special_case[key] : key.charAt(0).toUpperCase() + key.slice(1) );
        }
    }

    // return an **html** string of the keyboard shortcut
    // for human eyes consumption.
    // the sequence is a string, comma separated linkt of shortcut,
    // where the shortcut is a list of dash-joined keys.
    // Each shortcut will be wrapped in <kbd> tag, and joined by comma is in a
    // sequence.
    //
    // Depending on the platform each shortcut will be normalized, with or without dashes.
    // and replace with the corresponding unicode symbol for modifier if necessary.
    function humanize_sequence(sequence){
        var joinchar = ',';
        var hum = _.map(sequence.replace(/meta/g, 'cmd').split(','), humanize_shortcut).join(joinchar);
        return hum;
    }

    function _humanize_sequence(sequence){
        var joinchar = ',';
        var hum = _.map(sequence.replace(/meta/g, 'cmd').split(','), _humanize_shortcut).join(joinchar);
        return hum;
    }

    function _humanize_shortcut(shortcut){
        var joinchar = '-';
        if (platform === 'MacOS'){
            joinchar = '';
        }
        return _.map(shortcut.split('-'), humanize_key ).join(joinchar);
    }

    function humanize_shortcut(shortcut){
        return '<kbd>'+_humanize_shortcut(shortcut)+'</kbd>';
    }


    QuickHelp.prototype.show_keyboard_shortcuts = function () {
        /**
         * toggles display of keyboard shortcut dialog
         */
        var that = this;
        if ( this.force_rebuild ) {
            this.shortcut_dialog.remove();
            delete(this.shortcut_dialog);
            this.force_rebuild = false;
        }
        if ( this.shortcut_dialog ){
            // if dialog is already shown, close it
            $(this.shortcut_dialog).modal("toggle");
            return;
        }
        var element = $('<div/>');

        // The documentation
        var doc = $('<div/>').addClass('alert alert-info');
        doc.append(i18n.msg._('The Jupyter Notebook has two different keyboard input modes.'))
           .append(' ')
           .append(i18n.msg._('<b>Edit mode</b> allows you to type code or text into a cell and is indicated by a green cell border.'))
           .append(' ')
           .append(i18n.msg._('<b>Command mode</b> binds the keyboard to notebook level commands and is indicated by a grey cell border with a blue left margin.')
        );
        element.append(doc);
        if (platform === 'MacOS') {
            doc = $('<div/>').addClass('alert alert-info');
            var key_div = this.build_key_names();
            doc.append(key_div);
            element.append(doc);
        }

        // Command mode
        var cmd_div = this.build_command_help();
        element.append(cmd_div);

        // Edit mode
        var edit_div = this.build_edit_help(cm_shortcuts);
        element.append(edit_div);

        // This statement is used simply so that message extraction
        // will pick up the strings.  The actual setting of the text
        // for the button is in dialog.js.
        var button_labels = [ i18n.msg._("Close") ];

        this.shortcut_dialog = dialog.modal({
            title : i18n.msg._("Keyboard shortcuts"),
            body : element,
            destroy : false,
            buttons : {
                Close : {}
            },
            notebook: this.notebook,
            keyboard_manager: this.keyboard_manager,
        });
        this.shortcut_dialog.addClass("modal_stretch");

        this.events.on('rebuild.QuickHelp', function() { that.force_rebuild = true;});
    };

    QuickHelp.prototype.build_key_names = function () {
       var key_names_mac =  [{ shortcut:"⌘", help:i18n.msg._("Command") },
                    { shortcut:"⌃", help:i18n.msg._("Control") },
                    { shortcut:"⌥", help:i18n.msg._("Option") },
                    { shortcut:"⇧", help:i18n.msg._("Shift") },
                    { shortcut:"↩", help:i18n.msg._("Return") },
                    { shortcut:"␣", help:i18n.msg._("Space") },
                    { shortcut:"⇥", help:i18n.msg._("Tab") }];
        var i, half, n;
        var div = $('<div/>').append('Mac OS X modifier keys:');
        var sub_div = $('<div/>').addClass('container-fluid');
        var col1 = $('<div/>').addClass('col-md-6');
        var col2 = $('<div/>').addClass('col-md-6');
        n = key_names_mac.length;
        half = ~~(n/2);
        for (i=0; i<half; i++) { col1.append(
                build_one(key_names_mac[i])
                ); }
        for (i=half; i<n; i++) { col2.append(
                build_one(key_names_mac[i])
                ); }
        sub_div.append(col1).append(col2);
        div.append(sub_div);
        return div;
    };


    QuickHelp.prototype.build_command_help = function () {
        var that = this;
        var command_shortcuts = this.keyboard_manager.command_shortcuts.help();
        var cmdkey = '<kbd>'+i18n.msg._('Esc')+'</kbd>';
        var div = build_div('<h4>'+i18n.msg.sprintf(i18n.msg._('Command Mode (press %s to enable)'),cmdkey)+'</h4>', command_shortcuts);
        var edit_button = $('<button/>')
            .text(i18n.msg._("Edit Shortcuts"))
            .addClass('btn btn-xs btn-default pull-right')
            .attr('href', '#')
            .attr('title', i18n.msg._('edit command-mode keyboard shortcuts'))
            .click(function () {
                // close this dialog
                $(that.shortcut_dialog).modal("toggle");
                // and open the next one
                $(that.shortcut_dialog).on('hidden.bs.modal', function (e) {
                    that.keyboard_manager.actions.call(
                        'jupyter-notebook:edit-command-mode-keyboard-shortcuts'
                    );
                });
            });
        div.find('h4').append(edit_button);
        return div;
    };


    QuickHelp.prototype.build_edit_help = function (cm_shortcuts) {
        var edit_shortcuts = this.keyboard_manager.edit_shortcuts.help();
        var enterkey = '<kbd>'+i18n.msg._('Enter')+'</kbd>';
        edit_shortcuts = $.merge($.merge([], cm_shortcuts), edit_shortcuts);
        return build_div('<h4>'+i18n.msg.sprintf(i18n.msg._('Edit Mode (press %s to enable)'),enterkey)+'</h4>', edit_shortcuts);
    };

    var build_one = function (s) {
        var help = s.help;
        var shortcut = '';
        if(s.shortcut){
            shortcut = humanize_sequence(s.shortcut);
        }
        return $('<div>').addClass('quickhelp').
            append($('<span/>').addClass('shortcut_key').append($(shortcut))).
            append($('<span/>').addClass('shortcut_descr').text(' : ' + help));

    };

    var build_div = function (title, shortcuts) {

        // Remove jupyter-notebook:ignore shortcuts.
        shortcuts = shortcuts.filter(function(shortcut) {
            if (shortcut.help === 'ignore') {
                return false;
            } else {
                return true;
            }
        });

        var i, half, n;
        var div = $('<div/>').append($(title));
        var sub_div = $('<div/>').addClass('container-fluid');
        var col1 = $('<div/>').addClass('col-md-6');
        var col2 = $('<div/>').addClass('col-md-6');
        n = shortcuts.length;
        half = ~~(n/2);  // Truncate :)
        for (i=0; i<half; i++) { col1.append( build_one(shortcuts[i]) ); }
        for (i=half; i<n; i++) { col2.append( build_one(shortcuts[i]) ); }
        sub_div.append(col1).append(col2);
        div.append(sub_div);
        return div;
    };

    return {'QuickHelp': QuickHelp,
      humanize_shortcut: humanize_shortcut,
      humanize_sequence: humanize_sequence,
      _humanize_sequence: _humanize_sequence,
  };
});
