// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * @fileoverview Helper functions and objects for the JS debugger UI.
 * @see debugger.html
 */

/**
 * Document load listener.
 */
function onLoad() {
    var debuggerConsole = new DebuggerConsole();
    DebuggerIPC.init(debuggerConsole);
    DebugShell.initDebugShell(debuggerConsole);
    debuggerConsole.focusOnCommandLine();
}

/**
 * @constructor
 */
function DebuggerConsole()
{
    this._output = document.getElementById("output");
    
    var input = document.getElementById("command-line-text");
    var self = this;
    input.addEventListener(
        'keydown',
        function(e) {
          return self._onInputKeyDown(e);
        },
        true);
    input.addEventListener(
        'keypress',
        function(e) {
          return self._onInputKeyPress(e);
        },
        true);
    this._commandLineInput = input;
    
    // command object stores command-line history state.
    this._command = {
        history: [],
        history_index: 0,
        pending: null
    };
};

DebuggerConsole.prototype = {
    /**
     * Sets focus to command-line-text element.
     */
    focusOnCommandLine: function() {
        this._commandLineInput.focus();
    },

    /**
     * Called by chrome code when there's output to display.
     * @param {string} txt
     */
    appendText: function(txt) 
    {
        this._output.appendChild(document.createTextNode(txt));
        this._output.appendChild(document.createElement('br'));
        document.body.scrollTop = document.body.scrollHeight;
    },

    /**
     * Called by chrome code to set the current state as to whether the debugger
     * is stopped at a breakpoint or is running.
     * @param {boolean} isBroken
     */
    setDebuggerBreak: function(isBroken) 
    {
        var out = this._output;
        if (isBroken) {
            out.style.color = "black";
            this.focusOnCommandLine();
        } else {
            out.style.color = "gray";
        }
    },

    /**
     * Execute a debugger command, add it to the command history and display it in
     * the output window.
     * @param {string} str
     */
    executeCommand: function(str) {
        this.appendText("$ " + str);
        // Sends message to DebuggerContents.HandleCommand.
        if (DebugShell.singleton) {
            DebugShell.singleton.command(str);
        } else {
            this.appendText("FAILED to send the command as DebugShell is null");
        }
        
        this._command.history.push(str);
        this._command.history_index = this._command.history.length;
        this._command.pending = null;
    },
        

    /**
     * Display the previous history item in the given text field.
     * @param {HTMLInputElement} field
     */
    selectPreviousCommand_: function(field) {
        var command = this._command;
        if (command.history_index > 0) {
            // Remember the current field value as a pending command if we're at the
            // end (it's something the user typed in).
            if (command.history_index == command.history.length)
                command.pending = field.value;
            command.history_index--;
            field.value = command.history[command.history_index];
            field.select();
        }
    },

    /**
     * Display the next history item in the given text field.
     * @param {HTMLInputElement} field
     */
    selectNextCommand_: function(field) {
        var command = this._command;
        if (command.history_index < command.history.length) {
            command.history_index++;
            if (command.history_index == command.history.length) {
                field.value = command.pending || "";
            } else {
                field.value = command.history[command.history_index];
            }
            field.select();
        }
    },
    
    /**
     * command-line-text's onkeydown handler.
     * @param {KeyboardEvent} e
     * @return {boolean}
     */
    _onInputKeyDown: function (e) {
        var field = e.target;
        var key = e.keyCode;
        if (key == 38) { // up arrow
            this.selectPreviousCommand_(field);
            return false;
        } else if (key == 40) { // down arrow
            this.selectNextCommand_(field);
            return false;
        }
        return true;
    },

    /**
     * command-line-text's onkeypress handler.
     * @param {KeyboardEvent} e
     * @return {boolean}
     */
    _onInputKeyPress: function (e) {
        var field = e.target;
        var key = e.keyCode;
        if (key == 13) { // enter
            this.executeCommand(field.value);
            field.value = "";
            return false;
        }
        return true;
    }
};