<?php
/*
 * Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.com/ 
 * 
 * 
 *  Redistribution and use in source and binary forms, with or without 
 *  modification, are permitted provided that the following conditions 
 *  are met:
 *
 *    Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer.
 *
 *    Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the   
 *    distribution.
 *
 *    Neither the name of Texas Instruments Incorporated nor the names of
 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
 *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
 *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
*/

# 函数规定报告哪个错误,该函数设置当前脚本的错误报告级别
# 该函数返回旧的错误报告级别
error_reporting(E_ALL);

# 加载那些需要的函数
require("helper_functions.php");

$i = 0;
$lock_string = "";
$currently_locked = false;

$var = read_desktop_file();         # 加载json对象

if($var==null)
{
    echo "Json.txt file is empty or doesn't exist.";
    return;
}

$submenu = isset($_GET["submenu"]) == true ? $_GET["submenu"] : "main_menu" ;

# $link =  "run_script.php?&submenu=".urlencode($submenu)."&app=".urlencode($app_title);
# 获取对应的app
$found_app = get_application($var,$submenu,$_GET["app"]);

# 查看当前的json.txt文件，其中的Lock字段的内容都是-1
# 所以这一部分的其中很多内容可以不分析
$lock_list = $found_app["Lock"];

//Verify that there is a lock specified for this application
# 应用有锁
if($lock_list != -1 )
{
    //Convert the string into an array. 
    //This might be backwards*********CHECKOUT********
    # explode(): 把字符串分割为数组
    $lock_list_array = explode($lock_list," ");

    //Check if the lock list only has one lock. If so add to the array
    //Since index 0 will be empty
    if(count($lock_list_array) == 1)
        $lock_list_array[0] = $lock_list;

    //Check to see if any of the locks exist.
    for($x = 0;$x<count($lock_list_array);$x++)
    {
        # 这里貌似是锁文件,是否存在的意思
        if(file_exists ("lock/".$lock_list_array[$x])==true)
        {
            $currently_locked = true;
            break;
        }
    }
}
else
    $lock_list = "";        # 就当前的json.txt文件而言，都是采用这种方式

if($currently_locked==false)
{
    $script_link = $found_app["Exec"];

    # strval(): 用于获取变量对应的字符串值
    # rand(): 返回随机整数
    $random_string = strval(rand());
    $random_string .= strval(rand());

    # addslashes(): 在指定的预定义字符前添加反斜杠
    $script_command = "./execute_command.sh \"".addslashes($script_link). "\" ".$random_string.".txt ".$lock_list;

    # 获取系统执行结果最后一行
    # system()第二个参数：如果提供的return_var参数，则外部命令执行后的
    # 返回状态将会被设置到此变量中
    $last_line = system($script_command." > /dev/null 2>/dev/null & ", $retval);
}

# 菜单标题采用app的名字
$menu_title = $found_app["Name"];
?>

<!-- 这里需要区分web的程序还是gui程序 -->
<!-- 这里是没有锁，并且是程序类型不是web，也就是说gui程序会走接下来的这种方式 -->
<?php if($currently_locked==false && $found_app["ProgramType"]!="web"){ ?>
<!-- 加入菜单 -->
<?php include "menubar.php"; ?>
<div id="container"></div>

<script>
    <?php echo "var uri_link = \"$random_string\";"; ?>     // 仅仅是一个随机数

    var fail_count = 0;

    // 这个函数的主要功能好像是，获取app的输出内容显示到网页上来，
    // 但这个函数是有时间限制的，如果在规定的时间内不能获取到相应的数据，
    // 那么就会提示出错了
    function update()
    {
        //This is a fix for IE browsers. IE likes to cache Ajax results. Therefore, adding a random string will prevent the browser from caching the Ajax request. 
        // 防止浏览器缓存页面导致不访问web服务器
        var uri = "tmp/"+uri_link+".txt?rand="+Math.round((Math.random()*2356))+Math.round((Math.random()*4321))+Math.round((Math.random()*3961));
    
        $.get(uri, function(data) 
        {
            fail_count = 0;
            data = jQuery.trim(data);
   
            //The execute_command script adds the text "_?!!MATRIX_SCRIPT_COMPLETED!!?_" to the end of the file to mark that the command is done executing
            // 获取系统返回的数据,并查找字符串
            var script_complete = data.indexOf("_?!!MATRIX_SCRIPT_COMPLETED!!?_");
            if(script_complete != -1)
            {
                //Just replace the end of file text to Script Complete which 
                data = data.replace("_?!!MATRIX_SCRIPT_COMPLETED!!?_", "Script Complete");
            }

            <?php 
                //GUI applications shouldn't have any output that needs to be displayed. Therefore, don't include the code that will update the HTML container
                //with the program's output. This prevents some flickering problems that occur in some GUI applications even if the HTML container is being passed no information.
                // GUI程序没有任何输出需要显示，所以不需要将程序输出显示出来，
                // 这里主要是为了防止一些无输出的问题
                if($found_app["ProgramType"]!="gui"){ ?>
                $('#container').html("<pre>"+data+"</pre>");
                $('#container').scrollTop(document.getElementById("container").scrollHeight);        
            <?php } ?>

            if(script_complete != -1)
            {
                //Display the exit and back button.
                $('#main_menu_link').removeClass("hide_link");
                $('#back_link').removeClass("hide_link");

                <?php if($found_app["ProgramType"]=="gui"){ ?>
                    $('#back_link').click();            // 这里为什么会需要自动点击返回？
                <?php } ?>
            }
            else
                setTimeout("update()",1000);

        })
        //If a file cant be read or some other error related to trying to retrieve this file then JQuery executes the error function.
        //This sometimes occurs when the browser tries to read the output file before output file is even created. 
        .error(function() 
        { 
            //This function will attempt to read the file 3 times with an increase delay for each attempt. If the file still hasn't 
            //been able to be read then an error is displayed and the Exit and Back Link is enabled.

            fail_count++;
            if(fail_count==3)
            {
                $('#container').html("Failed to read output file");
                $('#main_menu_link').removeClass("hide_link");
                $('#back_link').removeClass("hide_link");
            }
            else
            {
                //Every time it fails wait a signifcantly longer amount of time
                setTimeout("update()",fail_count*1500);
            }
        });

    
    }
    
    //Wait 500ms before trying to read the application output
    // 从这里开始开始调用前面的update()函数
    setTimeout("update()",500);     
</script>
<?php }if($currently_locked==false && $found_app["ProgramType"]=="web"){ ?>
<?php include "menubar.php"; ?>

<script>
$('#main_menu_link').removeClass("hide_link");
$('#back_link').removeClass("hide_link");

$("#menubar").outerHeight(true)
$("#menubar").outerWidth(true)

// 在后面给调用
function scrollbarWidth() {
    var $inner = jQuery('<div style="width: 100%; height:200px;">test</div>'),
        $outer = jQuery('<div style="width:200px;height:150px; position: absolute; top: 0; left: 0; visibility: hidden; overflow:hidden;"></div>').append($inner),
        inner = $inner[0],
        outer = $outer[0];

    jQuery('body').append(outer);
    var width1 = inner.offsetWidth;
    $outer.css('overflow', 'scroll');
    var width2 = outer.clientWidth;
    $outer.remove();

    return (width1 - width2);
}

$("#html5-frame").width($("#menubar").width()-scrollbarWidth());
$("#html5-frame").height($(window).height() - $("#menubar").outerHeight(true)-scrollbarWidth())

</script>
<!-- 用一个框架来显示一些东西 -->
<iframe id = "html5-frame" src = "<?php echo $found_app["Exec"]; ?>"scrolling = "auto" style = "padding:5px;">

<!-- 就目前的json.txt文本内容而言，currently_locked一直都是等于false -->
<?php }if($currently_locked==true){?>
<?php include "menubar.php"; ?>
This program can't run since a program is already running that contains a lock that this program is trying to use
<script>
    //Display the back and exit button since the application couldn't run
    $('#main_menu_link').removeClass("hide_link");
    $('#back_link').removeClass("hide_link");
</script>

<?php } ?>