notebook.js

//----------------------------------------------------------------------------
//  Copyright (C) 2008-2011  The IPython Development Team
//
//  Distributed under the terms of the BSD License.  The full license is in
//  the file COPYING, distributed as part of this software.
//----------------------------------------------------------------------------

//============================================================================
// Notebook
//============================================================================

var IPython = (function (IPython) {

    var utils = IPython.utils;

    var Notebook = function (selector) {
        this.element = $(selector);
        this.element.scroll();
        this.element.data("notebook", this);
        this.next_prompt_number = 1;
        this.kernel = null;
        this.dirty = false;
        this.msg_cell_map = {};
        this.metadata = {};
        this.control_key_active = false;
        this.style();
        this.create_elements();
        this.bind_events();
    };


    Notebook.prototype.style = function () {
        $('div#notebook').addClass('border-box-sizing');
    };


    Notebook.prototype.create_elements = function () {
        // We add this end_space div to the end of the notebook div to:
        // i) provide a margin between the last cell and the end of the notebook
        // ii) to prevent the div from scrolling up when the last cell is being
        // edited, but is too low on the page, which browsers will do automatically.
        var that = this;
        var end_space = $('<div class="end_space"></div>').height(150);
        end_space.dblclick(function (e) {
            var ncells = that.ncells();
            that.insert_code_cell_below(ncells-1);
        });
        this.element.append(end_space);
        $('div#notebook').addClass('border-box-sizing');
    };


    Notebook.prototype.bind_events = function () {
        var that = this;
        $(document).keydown(function (event) {
            // console.log(event);
            if (event.which === 38) {
                var cell = that.selected_cell();
                if (cell.at_top()) {
                    event.preventDefault();
                    that.select_prev();
                };
            } else if (event.which === 40) {
                var cell = that.selected_cell();
                if (cell.at_bottom()) {
                    event.preventDefault();
                    that.select_next();
                };
            } else if (event.which === 13 && event.shiftKey) {
                that.execute_selected_cell();
                return false;
            } else if (event.which === 13 && event.ctrlKey) {
                that.execute_selected_cell({terminal:true});
                return false;
            } else if (event.which === 77 && event.ctrlKey) {
                that.control_key_active = true;
                return false;
            } else if (event.which === 68 && that.control_key_active) {
                // Delete selected cell = d
                that.delete_cell();
                that.control_key_active = false;
                return false;
            } else if (event.which === 65 && that.control_key_active) {
                // Insert code cell above selected = a
                that.insert_code_cell_above();
                that.control_key_active = false;
                return false;
            } else if (event.which === 66 && that.control_key_active) {
                // Insert code cell below selected = b
                that.insert_code_cell_below();
                that.control_key_active = false;
                return false;
            } else if (event.which === 67 && that.control_key_active) {
                // To code = c
                that.to_code();
                that.control_key_active = false;
                return false;
            } else if (event.which === 77 && that.control_key_active) {
                // To markdown = m
                that.to_markdown();
                that.control_key_active = false;
                return false;
            } else if (event.which === 84 && that.control_key_active) {
                // Toggle output = t
                that.toggle_output();
                that.control_key_active = false;
                return false;
            } else if (event.which === 83 && that.control_key_active) {
                // Save notebook = s
                IPython.save_widget.save_notebook();
                that.control_key_active = false;
                return false;
            } else if (event.which === 74 && that.control_key_active) {
                // Move cell down = j
                that.move_cell_down();
                that.control_key_active = false;
                return false;
            } else if (event.which === 75 && that.control_key_active) {
                // Move cell up = k
                that.move_cell_up();
                that.control_key_active = false;
                return false;
            } else if (event.which === 80 && that.control_key_active) {
                // Select previous = p
                that.select_prev();
                that.control_key_active = false;
                return false;
            } else if (event.which === 78 && that.control_key_active) {
                // Select next = n
                that.select_next();
                that.control_key_active = false;
                return false;
            } else if (event.which === 76 && that.control_key_active) {
                // Toggle line numbers = l
                that.cell_toggle_line_numbers();
                that.control_key_active = false;
                return false;
            } else if (event.which === 73 && that.control_key_active) {
                // Interrupt kernel = i
                IPython.notebook.kernel.interrupt();
                that.control_key_active = false;
                return false;
            } else if (event.which === 190 && that.control_key_active) {
                // Restart kernel = .  # matches qt console
                IPython.notebook.restart_kernel();
                that.control_key_active = false;
                return false;
            } else if (event.which === 72 && that.control_key_active) {
                // Show keyboard shortcuts = h
                that.toggle_keyboard_shortcuts();
                that.control_key_active = false;
                return false;
            } else if (that.control_key_active) {
                that.control_key_active = false;
                return true;
            };
        });

        this.element.bind('collapse_pager', function () {
            var app_height = $('div#main_app').height(); // content height
            var splitter_height = $('div#pager_splitter').outerHeight(true);
            var new_height = app_height - splitter_height;
            that.element.animate({height : new_height + 'px'}, 'fast');
        });

        this.element.bind('expand_pager', function () {
            var app_height = $('div#main_app').height(); // content height
            var splitter_height = $('div#pager_splitter').outerHeight(true);
            var pager_height = $('div#pager').outerHeight(true);
            var new_height = app_height - pager_height - splitter_height; 
            that.element.animate({height : new_height + 'px'}, 'fast');
        });

        this.element.bind('collapse_left_panel', function () {
            var splitter_width = $('div#left_panel_splitter').outerWidth(true);
            var new_margin = splitter_width;
            $('div#notebook_panel').animate({marginLeft : new_margin + 'px'}, 'fast');
        });

        this.element.bind('expand_left_panel', function () {
            var splitter_width = $('div#left_panel_splitter').outerWidth(true);
            var left_panel_width = IPython.left_panel.width;
            var new_margin = splitter_width + left_panel_width;
            $('div#notebook_panel').animate({marginLeft : new_margin + 'px'}, 'fast');
        });

        $(window).bind('beforeunload', function () {
            var kill_kernel = $('#kill_kernel').prop('checked');                
            if (kill_kernel) {
                that.kernel.kill();
            }
            if (that.dirty) {
                return "You have unsaved changes that will be lost if you leave this page.";
            };
        });
    };


    Notebook.prototype.toggle_keyboard_shortcuts = function () {
        // toggles display of keyboard shortcut dialog
        var that = this;
        if ( this.shortcut_dialog ){
            // if dialog is already shown, close it
            this.shortcut_dialog.dialog("close");
            this.shortcut_dialog = null;
            return;
        }
        var dialog = $('<div/>');
        this.shortcut_dialog = dialog;
        var shortcuts = [
            {key: 'Shift-Enter', help: 'run cell'},
            {key: 'Ctrl-Enter', help: 'run cell in-place'},
            {key: 'Ctrl-m d', help: 'delete cell'},
            {key: 'Ctrl-m a', help: 'insert cell above'},
            {key: 'Ctrl-m b', help: 'insert cell below'},
            {key: 'Ctrl-m t', help: 'toggle output'},
            {key: 'Ctrl-m l', help: 'toggle line numbers'},
            {key: 'Ctrl-m s', help: 'save notebook'},
            {key: 'Ctrl-m j', help: 'move cell down'},
            {key: 'Ctrl-m k', help: 'move cell up'},
            {key: 'Ctrl-m c', help: 'code cell'},
            {key: 'Ctrl-m m', help: 'markdown cell'},
            {key: 'Ctrl-m p', help: 'select previous'},
            {key: 'Ctrl-m n', help: 'select next'},
            {key: 'Ctrl-m i', help: 'interrupt kernel'},
            {key: 'Ctrl-m .', help: 'restart kernel'},
            {key: 'Ctrl-m h', help: 'show keyboard shortcuts'}
        ];
        for (var i=0; i<shortcuts.length; i++) {
            dialog.append($('<div>').
                append($('<span/>').addClass('shortcut_key').html(shortcuts[i].key)).
                append($('<span/>').addClass('shortcut_descr').html(' : ' + shortcuts[i].help))
            );
        };
        dialog.bind('dialogclose', function(event) {
            // dialog has been closed, allow it to be drawn again.
            that.shortcut_dialog = null;
        });
        dialog.dialog({title: 'Keyboard shortcuts'});
    };


    Notebook.prototype.scroll_to_bottom = function () {
        this.element.animate({scrollTop:this.element.get(0).scrollHeight}, 0);
    };


    Notebook.prototype.scroll_to_top = function () {
        this.element.animate({scrollTop:0}, 0);
    };


    // Cell indexing, retrieval, etc.


    Notebook.prototype.cell_elements = function () {
        return this.element.children("div.cell");
    }


    Notebook.prototype.ncells = function (cell) {
        return this.cell_elements().length;
    }


    // TODO: we are often calling cells as cells()[i], which we should optimize
    // to cells(i) or a new method.
    Notebook.prototype.cells = function () {
        return this.cell_elements().toArray().map(function (e) {
            return $(e).data("cell");
        });
    }


    Notebook.prototype.find_cell_index = function (cell) {
        var result = null;
        this.cell_elements().filter(function (index) {
            if ($(this).data("cell") === cell) {
                result = index;
            };
        });
        return result;
    };


    Notebook.prototype.index_or_selected = function (index) {
        return index || this.selected_index() || 0;
    }


    Notebook.prototype.select = function (index) {
        if (index !== undefined && index >= 0 && index < this.ncells()) {
            if (this.selected_index() !== null) {
                this.selected_cell().unselect();
            };
            this.cells()[index].select();
        };
        return this;
    };


    Notebook.prototype.select_next = function () {
        var index = this.selected_index();
        if (index !== null && index >= 0 && (index+1) < this.ncells()) {
            this.select(index+1);
        };
        return this;
    };


    Notebook.prototype.select_prev = function () {
        var index = this.selected_index();
        if (index !== null && index >= 0 && (index-1) < this.ncells()) {
            this.select(index-1);
        };
        return this;
    };


    Notebook.prototype.selected_index = function () {
        var result = null;
        this.cell_elements().filter(function (index) {
            if ($(this).data("cell").selected === true) {
                result = index;
            };
        });
        return result;
    };


    Notebook.prototype.cell_for_msg = function (msg_id) {
        var cell_id = this.msg_cell_map[msg_id];
        var result = null;
        this.cell_elements().filter(function (index) {
            cell = $(this).data("cell");
            if (cell.cell_id === cell_id) {
                result = cell;
            };
        });
        return result;
    };


    Notebook.prototype.selected_cell = function () {
        return this.cell_elements().eq(this.selected_index()).data("cell");
    }


    // Cell insertion, deletion and moving.


    Notebook.prototype.delete_cell = function (index) {
        var i = index || this.selected_index();
        if (i !== null && i >= 0 && i < this.ncells()) {
            this.cell_elements().eq(i).remove();
            if (i === (this.ncells())) {
                this.select(i-1);
            } else {
                this.select(i);
            };
        };
        this.dirty = true;
        return this;
    };


    Notebook.prototype.append_cell = function (cell) {
        this.element.find('div.end_space').before(cell.element);
        this.dirty = true;
        return this;
    };


    Notebook.prototype.insert_cell_below = function (cell, index) {
        var ncells = this.ncells();
        if (ncells === 0) {
            this.append_cell(cell);
            return this;
        };
        if (index >= 0 && index < ncells) {
            this.cell_elements().eq(index).after(cell.element);
        };
        this.dirty = true;
        return this
    };


    Notebook.prototype.insert_cell_above = function (cell, index) {
        var ncells = this.ncells();
        if (ncells === 0) {
            this.append_cell(cell);
            return this;
        };
        if (index >= 0 && index < ncells) {
            this.cell_elements().eq(index).before(cell.element);
        };
        this.dirty = true;
        return this;
    };


    Notebook.prototype.move_cell_up = function (index) {
        var i = index || this.selected_index();
        if (i !== null && i < this.ncells() && i > 0) {
            var pivot = this.cell_elements().eq(i-1);
            var tomove = this.cell_elements().eq(i);
            if (pivot !== null && tomove !== null) {
                tomove.detach();
                pivot.before(tomove);
                this.select(i-1);
            };
        };
        this.dirty = true;
        return this;
    }


    Notebook.prototype.move_cell_down = function (index) {
        var i = index || this.selected_index();
        if (i !== null && i < (this.ncells()-1) && i >= 0) {
            var pivot = this.cell_elements().eq(i+1)
            var tomove = this.cell_elements().eq(i)
            if (pivot !== null && tomove !== null) {
                tomove.detach();
                pivot.after(tomove);
                this.select(i+1);
            };
        };
        this.dirty = true;
        return this;
    }


    Notebook.prototype.sort_cells = function () {
        var ncells = this.ncells();
        var sindex = this.selected_index();
        var swapped;
        do {
            swapped = false
            for (var i=1; i<ncells; i++) {
                current = this.cell_elements().eq(i).data("cell");
                previous = this.cell_elements().eq(i-1).data("cell");
                if (previous.input_prompt_number > current.input_prompt_number) {
                    this.move_cell_up(i);
                    swapped = true;
                };
            };
        } while (swapped);
        this.select(sindex);
        return this;
    };


    Notebook.prototype.insert_code_cell_above = function (index) {
        // TODO: Bounds check for i
        var i = this.index_or_selected(index);
        var cell = new IPython.CodeCell(this);
        cell.set_input_prompt();
        this.insert_cell_above(cell, i);
        this.select(this.find_cell_index(cell));
        return cell;
    }


    Notebook.prototype.insert_code_cell_below = function (index) {
        // TODO: Bounds check for i
        var i = this.index_or_selected(index);
        var cell = new IPython.CodeCell(this);
        cell.set_input_prompt();
        this.insert_cell_below(cell, i);
        this.select(this.find_cell_index(cell));
        return cell;
    }


    Notebook.prototype.insert_html_cell_above = function (index) {
        // TODO: Bounds check for i
        var i = this.index_or_selected(index);
        var cell = new IPython.HTMLCell(this);
        cell.config_mathjax();
        this.insert_cell_above(cell, i);
        this.select(this.find_cell_index(cell));
        return cell;
    }


    Notebook.prototype.insert_html_cell_below = function (index) {
        // TODO: Bounds check for i
        var i = this.index_or_selected(index);
        var cell = new IPython.HTMLCell(this);
        cell.config_mathjax();
        this.insert_cell_below(cell, i);
        this.select(this.find_cell_index(cell));
        return cell;
    }


    Notebook.prototype.insert_markdown_cell_above = function (index) {
        // TODO: Bounds check for i
        var i = this.index_or_selected(index);
        var cell = new IPython.MarkdownCell(this);
        cell.config_mathjax();
        this.insert_cell_above(cell, i);
        this.select(this.find_cell_index(cell));
        return cell;
    }


    Notebook.prototype.insert_markdown_cell_below = function (index) {
        // TODO: Bounds check for i
        var i = this.index_or_selected(index);
        var cell = new IPython.MarkdownCell(this);
        cell.config_mathjax();
        this.insert_cell_below(cell, i);
        this.select(this.find_cell_index(cell));
        return cell;
    }


    Notebook.prototype.to_code = function (index) {
        // TODO: Bounds check for i
        var i = this.index_or_selected(index);
        var source_element = this.cell_elements().eq(i);
        var source_cell = source_element.data("cell");
        if (source_cell instanceof IPython.HTMLCell || 
            source_cell instanceof IPython.MarkdownCell) {
            this.insert_code_cell_below(i);
            var target_cell = this.cells()[i+1];
            target_cell.set_code(source_cell.get_source());
            source_element.remove();
            target_cell.select();
        };
        this.dirty = true;
    };


    Notebook.prototype.to_markdown = function (index) {
        // TODO: Bounds check for i
        var i = this.index_or_selected(index);
        var source_element = this.cell_elements().eq(i);
        var source_cell = source_element.data("cell");
        var target_cell = null;
        if (source_cell instanceof IPython.CodeCell) {
            this.insert_markdown_cell_below(i);
            var target_cell = this.cells()[i+1];
            var text = source_cell.get_code();
        } else if (source_cell instanceof IPython.HTMLCell) {
            this.insert_markdown_cell_below(i);
            var target_cell = this.cells()[i+1];
            var text = source_cell.get_source();
            if (text === source_cell.placeholder) {
                text = target_cell.placeholder;
            }
        }
        if (target_cell !== null) {
            if (text === "") {text = target_cell.placeholder;};
            target_cell.set_source(text);
            source_element.remove();
            target_cell.edit();
        }
        this.dirty = true;
    };


    Notebook.prototype.to_html = function (index) {
        // TODO: Bounds check for i
        var i = this.index_or_selected(index);
        var source_element = this.cell_elements().eq(i);
        var source_cell = source_element.data("cell");
        var target_cell = null;
        if (source_cell instanceof IPython.CodeCell) {
            this.insert_html_cell_below(i);
            var target_cell = this.cells()[i+1];
            var text = source_cell.get_code();
        } else if (source_cell instanceof IPython.MarkdownCell) {
            this.insert_html_cell_below(i);
            var target_cell = this.cells()[i+1];
            var text = source_cell.get_source();
            if (text === source_cell.placeholder) {
                text = target_cell.placeholder;
            }
        }
        if (target_cell !== null) {
            if (text === "") {text = target_cell.placeholder;};
            target_cell.set_source(text);
            source_element.remove();
            target_cell.edit();
        }
        this.dirty = true;
    };


    // Cell collapsing and output clearing

    Notebook.prototype.collapse = function (index) {
        var i = this.index_or_selected(index);
        this.cells()[i].collapse();
        this.dirty = true;
    };


    Notebook.prototype.expand = function (index) {
        var i = this.index_or_selected(index);
        this.cells()[i].expand();
        this.dirty = true;
    };


    Notebook.prototype.toggle_output = function (index) {
        var i = this.index_or_selected(index);
        this.cells()[i].toggle_output();
        this.dirty = true;
    };


    Notebook.prototype.set_autoindent = function (state) {
        var cells = this.cells();
        len = cells.length;
        for (var i=0; i<len; i++) {
            cells[i].set_autoindent(state)
        };
    };


    Notebook.prototype.clear_all_output = function () {
        var ncells = this.ncells();
        var cells = this.cells();
        for (var i=0; i<ncells; i++) {
            if (cells[i] instanceof IPython.CodeCell) {
                cells[i].clear_output(true,true,true);
            }
        };
        this.dirty = true;
    };

    // Other cell functions: line numbers, ...

    Notebook.prototype.cell_toggle_line_numbers = function() {
        this.selected_cell().toggle_line_numbers()
    };

    // Kernel related things

    Notebook.prototype.start_kernel = function () {
        this.kernel = new IPython.Kernel();
        var notebook_id = IPython.save_widget.get_notebook_id();
        this.kernel.start(notebook_id, $.proxy(this.kernel_started, this));
    };


    Notebook.prototype.restart_kernel = function () {
        var that = this;
        var notebook_id = IPython.save_widget.get_notebook_id();

        var dialog = $('<div/>');
        dialog.html('Do you want to restart the current kernel?  You will lose all variables defined in it.');
        $(document).append(dialog);
        dialog.dialog({
            resizable: false,
            modal: true,
            title: "Restart kernel or continue running?",
            buttons : {
                "Restart": function () {
                    that.kernel.restart($.proxy(that.kernel_started, that));
                    $(this).dialog('close');
                },
                "Continue running": function () {
                    $(this).dialog('close');
                }
            }
        });
    };


    Notebook.prototype.kernel_started = function () {
        console.log("Kernel started: ", this.kernel.kernel_id);
        this.kernel.shell_channel.onmessage = $.proxy(this.handle_shell_reply,this);
        this.kernel.iopub_channel.onmessage = $.proxy(this.handle_iopub_reply,this);
    };


    Notebook.prototype.handle_shell_reply = function (e) {
        reply = $.parseJSON(e.data);
        var header = reply.header;
        var content = reply.content;
        var msg_type = header.msg_type;
        // console.log(reply);
        var cell = this.cell_for_msg(reply.parent_header.msg_id);
        if (msg_type === "execute_reply") {
            cell.set_input_prompt(content.execution_count);
            this.dirty = true;
        } else if (msg_type === "complete_reply") {
            cell.finish_completing(content.matched_text, content.matches);
        };
        var payload = content.payload || [];
        this.handle_payload(cell, payload);
    };


    Notebook.prototype.handle_payload = function (cell, payload) {
        var l = payload.length;
        for (var i=0; i<l; i++) {
            if (payload[i].source === 'IPython.zmq.page.page') {
                if (payload[i].text.trim() !== '') {
                    IPython.pager.clear();
                    IPython.pager.expand();
                    IPython.pager.append_text(payload[i].text);
                }
            } else if (payload[i].source === 'IPython.zmq.zmqshell.ZMQInteractiveShell.set_next_input') {
                var index = this.find_cell_index(cell);
                var new_cell = this.insert_code_cell_below(index);
                new_cell.set_code(payload[i].text);
                this.dirty = true;
            }
        };
    };


    Notebook.prototype.handle_iopub_reply = function (e) {
        reply = $.parseJSON(e.data);
        var content = reply.content;
        // console.log(reply);
        var msg_type = reply.header.msg_type;
        var cell = this.cell_for_msg(reply.parent_header.msg_id);
        var output_types = ['stream','display_data','pyout','pyerr'];
        if (output_types.indexOf(msg_type) >= 0) {
            this.handle_output(cell, msg_type, content);
        } else if (msg_type === 'status') {
            if (content.execution_state === 'busy') {
                IPython.kernel_status_widget.status_busy();
            } else if (content.execution_state === 'idle') {
                IPython.kernel_status_widget.status_idle();
            } else if (content.execution_state === 'dead') {
                this.handle_status_dead();
            };
        } else if (msg_type === 'clear_output') {
            cell.clear_output(content.stdout, content.stderr, content.other);
        };
    };


    Notebook.prototype.handle_status_dead = function () {
        var that = this;
        this.kernel.stop_channels();
        var dialog = $('<div/>');
        dialog.html('The kernel has died, would you like to restart it? If you do not restart the kernel, you will be able to save the notebook, but running code will not work until the notebook is reopened.');
        $(document).append(dialog);
        dialog.dialog({
            resizable: false,
            modal: true,
            title: "Dead kernel",
            buttons : {
                "Restart": function () {
                    that.start_kernel();
                    $(this).dialog('close');
                },
                "Continue running": function () {
                    $(this).dialog('close');
                }
            }
        });
    };


    Notebook.prototype.handle_output = function (cell, msg_type, content) {
        var json = {};
        json.output_type = msg_type;
        if (msg_type === "stream") {
            json.text = utils.fixConsole(content.data);
            json.stream = content.name;
        } else if (msg_type === "display_data") {
            json = this.convert_mime_types(json, content.data);
        } else if (msg_type === "pyout") {
            json.prompt_number = content.execution_count;
            json = this.convert_mime_types(json, content.data);
        } else if (msg_type === "pyerr") {
            json.ename = content.ename;
            json.evalue = content.evalue;
            var traceback = [];
            for (var i=0; i<content.traceback.length; i++) {
                traceback.push(utils.fixConsole(content.traceback[i]));
            }
            json.traceback = traceback;
        };
        cell.append_output(json);
        this.dirty = true;
    };


    Notebook.prototype.convert_mime_types = function (json, data) {
        if (data['text/plain'] !== undefined) {
            json.text = utils.fixConsole(data['text/plain']);
        };
        if (data['text/html'] !== undefined) {
            json.html = data['text/html'];
        };
        if (data['image/svg+xml'] !== undefined) {
            json.svg = data['image/svg+xml'];
        };
        if (data['image/png'] !== undefined) {
            json.png = data['image/png'];
        };
        if (data['image/jpeg'] !== undefined) {
            json.jpeg = data['image/jpeg'];
        };
        if (data['text/latex'] !== undefined) {
            json.latex = data['text/latex'];
        };
        if (data['application/json'] !== undefined) {
            json.json = data['application/json'];
        };
        if (data['application/javascript'] !== undefined) {
            json.javascript = data['application/javascript'];
        }
        return json;    
    };


    Notebook.prototype.execute_selected_cell = function (options) {
        // add_new: should a new cell be added if we are at the end of the nb
        // terminal: execute in terminal mode, which stays in the current cell
        default_options = {terminal: false, add_new: true}
        $.extend(default_options, options)
        var that = this;
        var cell = that.selected_cell();
        var cell_index = that.find_cell_index(cell);
        if (cell instanceof IPython.CodeCell) {
            cell.clear_output(true, true, true);
            var code = cell.get_code();
            var msg_id = that.kernel.execute(cell.get_code());
            that.msg_cell_map[msg_id] = cell.cell_id;
        } else if (cell instanceof IPython.HTMLCell) {
            cell.render();
        }
        if (default_options.terminal) {
            cell.select_all();
        } else {
            if ((cell_index === (that.ncells()-1)) && default_options.add_new) {
                that.insert_code_cell_below();
                // If we are adding a new cell at the end, scroll down to show it.
                that.scroll_to_bottom();
            } else {
                that.select(cell_index+1);
            };
        };
        this.dirty = true;
    };


    Notebook.prototype.execute_all_cells = function () {
        var ncells = this.ncells();
        for (var i=0; i<ncells; i++) {
            this.select(i);
            this.execute_selected_cell({add_new:false});
        };
        this.scroll_to_bottom();
    };


    Notebook.prototype.complete_cell = function (cell, line, cursor_pos) {
        var msg_id = this.kernel.complete(line, cursor_pos);
        this.msg_cell_map[msg_id] = cell.cell_id;
    };

    // Persistance and loading


    Notebook.prototype.fromJSON = function (data) {
        var ncells = this.ncells();
        for (var i=0; i<ncells; i++) {
            // Always delete cell 0 as they get renumbered as they are deleted.
            this.delete_cell(0);
        };
        // Save the metadata
        this.metadata = data.metadata;
        // Only handle 1 worksheet for now.
        var worksheet = data.worksheets[0];
        if (worksheet !== undefined) {
            var new_cells = worksheet.cells;
            ncells = new_cells.length;
            var cell_data = null;
            var new_cell = null;
            for (var i=0; i<ncells; i++) {
                cell_data = new_cells[i];
                if (cell_data.cell_type == 'code') {
                    new_cell = this.insert_code_cell_below();
                    new_cell.fromJSON(cell_data);
                } else if (cell_data.cell_type === 'html') {
                    new_cell = this.insert_html_cell_below();
                    new_cell.fromJSON(cell_data);
                } else if (cell_data.cell_type === 'markdown') {
                    new_cell = this.insert_markdown_cell_below();
                    new_cell.fromJSON(cell_data);
                };
            };          
        };
    };


    Notebook.prototype.toJSON = function () {
        var cells = this.cells();
        var ncells = cells.length;
        cell_array = new Array(ncells);
        for (var i=0; i<ncells; i++) {
            cell_array[i] = cells[i].toJSON();
        };
        data = {
            // Only handle 1 worksheet for now.
            worksheets : [{cells:cell_array}],
            metadata : this.metadata
        }
        return data
    };

    Notebook.prototype.save_notebook = function () {
        if (IPython.save_widget.test_notebook_name()) {
            var notebook_id = IPython.save_widget.get_notebook_id();
            var nbname = IPython.save_widget.get_notebook_name();
            // We may want to move the name/id/nbformat logic inside toJSON?
            var data = this.toJSON();
            data.metadata.name = nbname;
            data.nbformat = 2;
            // We do the call with settings so we can set cache to false.
            var settings = {
                processData : false,
                cache : false,
                type : "PUT",
                data : JSON.stringify(data),
                headers : {'Content-Type': 'application/json'},
                success : $.proxy(this.notebook_saved,this),
                error : $.proxy(this.notebook_save_failed,this)
            };
            IPython.save_widget.status_saving();
            $.ajax("/notebooks/" + notebook_id, settings);
        };
    };


    Notebook.prototype.notebook_saved = function (data, status, xhr) {
        this.dirty = false;
        IPython.save_widget.notebook_saved();
        setTimeout($.proxy(IPython.save_widget.status_save,IPython.save_widget),500);
    }


    Notebook.prototype.notebook_save_failed = function (xhr, status, error_msg) {
        // Notify the user and reset the save button
        // TODO: Handle different types of errors (timeout etc.)
        alert('An unexpected error occured while saving the notebook.');
        setTimeout($.proxy(IPython.save_widget.reset_status,IPython.save_widget),500);                                                                               
    }


    Notebook.prototype.load_notebook = function (callback) {
        var that = this;
        var notebook_id = IPython.save_widget.get_notebook_id();
        // We do the call with settings so we can set cache to false.
        var settings = {
            processData : false,
            cache : false,
            type : "GET",
            dataType : "json",
            success : function (data, status, xhr) {
                that.notebook_loaded(data, status, xhr);
                if (callback !== undefined) {
                    callback();
                };
            }
        };
        IPython.save_widget.status_loading();
        $.ajax("/notebooks/" + notebook_id, settings);
    }


    Notebook.prototype.notebook_loaded = function (data, status, xhr) {
        this.fromJSON(data);
        if (this.ncells() === 0) {
            this.insert_code_cell_below();
        };
        IPython.save_widget.status_save();
        IPython.save_widget.set_notebook_name(data.metadata.name);
        this.start_kernel();
        this.dirty = false;
        // fromJSON always selects the last cell inserted. We need to wait
        // until that is done before scrolling to the top.
        setTimeout(function () {
            IPython.notebook.select(0);
            IPython.notebook.scroll_to_top();
        }, 50);
    };

    IPython.Notebook = Notebook;

    return IPython;

}(IPython));