var systemDB;
 
/*! Initialize the systemDB global variable. */
function initDB()
{
 
 
try {
    if (!window.openDatabase) {
        alert('not supported');
    } else {
        var shortName = 'mydatabase';
        var version = '1.0';
        var displayName = 'My Important Database';
        var maxSize = 65536; // in bytes
        var myDB = openDatabase(shortName, version, displayName, maxSize);
 
        // You should have a database instance in myDB.
 
    }
} catch(e) {
    // Error handling code goes here.
    if (e == INVALID_STATE_ERR) {
        // Version number mismatch.
    alert("Invalid database version.");
    } else {
    alert("Unknown error "+e+".");
    }
    return;
}
 
// alert("Database is: "+myDB);
 
createTables(myDB);
systemDB = myDB;
 
}
 
 
/*! Format a link to a document for display in the "Choose a file" pane. */
function docLink(row)
{
    var name = row['name'];
    var files_id = row['id'];
 
    return "<tr class='filerow'><td class='filenamecell'>"+name+"</td><td class='filelinkcell'>(<a href='#' onClick=loadFile("+files_id+")>edit</a>)&nbsp;(<a href='#' onClick=deleteFile("+files_id+")>delete</a>)</td></tr>\n";
}
 
/*! If a deletion resulted in a change in the list of files, redraw the "Choose a file" pane. */
function deleteUpdateResults(transaction, results)
{
    if (results.rowsAffected) {
        chooseDialog();
    }
}
 
/*! Mark a file as "deleted". */
function reallyDelete(id)
{
    // alert('delete ID: '+id);
    var myDB = systemDB;
 
    myDB.transaction(
        new Function("transaction", "transaction.executeSql('UPDATE files set deleted=1 where id=?;', [ "+id+" ], /* array of values for the ? placeholders */"+
            "deleteUpdateResults, errorHandler);")
    );
 
}
 
/*! Ask for user confirmation before deleting a file. */
function deleteFile(id)
{
    var myDB = systemDB;
 
    myDB.transaction(
        new Function("transaction", "transaction.executeSql('SELECT id,name from files where id=?;', [ "+id+" ], /* array of values for the ? placeholders */"+
            "function (transaction, results) {"+
                "if (confirm('Really delete '+results.rows.item(0)['name']+'?')) {"+
                    "reallyDelete(results.rows.item(0)['id']);"+
                "}"+
            "}, errorHandler);")
    );
}
 
/*! This prints a list of "files" to edit. */
function chooseDialog()
{
    var myDB = systemDB;
 
    myDB.transaction(
        function (transaction) {
        transaction.executeSql("SELECT * from files where deleted=0;",
            [ ], // array of values for the ? placeholders
            function (transaction, results) {
                var string = '';
                var controldiv = document.getElementById('controldiv');
                for (var i=0; i<results.rows.length; i++) {
                    var row = results.rows.item(i);
                    string = string + docLink(row);
                }
                if (string == "") {
                    string = "No files.<br />\n";
                } else {
                    string = "<table class='filetable'>"+string+"</table>";
                }
                controldiv.innerHTML="<H1>Choose a file to edit</H1>"+string+linkToCreateNewFile();
            }, errorHandler);
        }
    );
 
}
 
/*! This prints a link to the "Create file" pane. */
function linkToCreateNewFile()
{
    return "<p><button onClick='createNewFile()'>Create New File</button>";
}
 
 
/*! This creates a new "file" in the database. */
function createNewFileAction()
{
    var myDB = systemDB;
    var name = document.getElementById('createFilename').value
 
    // alert('Name is "'+name+'"');
 
    myDB.transaction(
        function (transaction) {
            var myfunc = new Function("transaction", "results", "/* alert('insert ID is'+results.insertId); */ transaction.executeSql('INSERT INTO files (name, filedata_id) VALUES (?, ?);', [ '"+name+"', results.insertId], nullDataHandler, killTransaction);");
 
                transaction.executeSql('INSERT INTO filedata (datablob) VALUES ("");', [],
                myfunc, errorHandler);
        }
    );
 
    chooseDialog();
}
 
/*! This saves the contents of the file. */
function saveFile()
{
    var myDB = systemDB;
    // alert("Save not implemented.\n");
 
    var contentdiv = document.getElementById('contentdiv');
    var contents = contentdiv.contentDocument.body.innerHTML;
 
    // alert('file text is '+contents);
 
    myDB.transaction(
        function (transaction) {
            var contentdiv = document.getElementById('contentdiv');
            var datadiv = document.getElementById('tempdata');
 
            var filedata_id = datadiv.getAttribute('lfdataid');
            var contents = contentdiv.contentDocument.body.innerHTML;
 
            transaction.executeSql("UPDATE filedata set datablob=? where id=?;",
                [ contents, filedata_id ], // array of values for the ? placeholders
                nullDataHandler, errorHandler);
            // alert('Saved contents to '+filedata_id+': '+contents);
            var origcontentdiv = document.getElementById('origcontentdiv');
            origcontentdiv.innerHTML = contents;
 
            alert('Saved.');
            }
    );
}
 
/*! This displays the "Create file" pane. */
function createNewFile()
{
    var myDB = systemDB;
    var controldiv = document.getElementById('controldiv');
    var string = "";
 
    string += "<H1>Create New File</H1>\n";
    string += "<form action='javascript:createNewFileAction()'>\n";
    string += "<input id='createFilename' name='name'>Filename</input>\n";
    string += "<input type='submit' value='submit' />\n";
    string += "</form>\n";
 
    controldiv.innerHTML=string;
 
}
 
/*! This processes the data read from the database by loadFile and sets up the editing environment. */
function loadFileData(transaction, results)
{
    var controldiv = document.getElementById('controldiv');
    var contentdiv = document.getElementById('contentdiv');
    var origcontentdiv = document.getElementById('origcontentdiv');
    var datadiv = document.getElementById('tempdata');
 
    // alert('loadFileData called.');
 
    var data = results.rows.item(0);
    var filename = data['name'];
    var filedata = data['datablob'];
    datadiv.setAttribute('lfdataid', parseInt(data['filedata_id']));
 
    document.title="Editing "+filename;
    controldiv.innerHTML="";
    contentdiv.contentDocument.body.innerHTML=filedata;
    origcontentdiv.innerHTML=filedata;
    contentdiv.style.border="1px solid #000000";
    contentdiv.style['min-height']='20px';
    contentdiv.style.display='block';
    contentdiv.contentDocument.contentEditable=true;
}
 
/*! This loads a "file" from the database and calls loadFileData with the results. */
function loadFile(id)
{
    // alert('Loading file with id '+id);
    var datadiv = document.getElementById('tempdata');
    datadiv.setAttribute('lfid', parseInt(id));
 
    myDB = systemDB;
    myDB.transaction(
        function (transaction) {
            var datadiv = document.getElementById('tempdata');
            var id = datadiv.getAttribute('lfid');
            // alert('loading id' +id);
            transaction.executeSql('SELECT * from files, filedata where files.id=? and files.filedata_id = filedata.id;', [id ], loadFileData, errorHandler);
        }
    );
 
}
 
/*! This creates the database tables. */
function createTables(db)
{
 
/* To wipe out the table (if you are still experimenting with schemas,
   for example), enable this block. */
if (0) {
    db.transaction(
        function (transaction) {
        transaction.executeSql('DROP TABLE files;');
        transaction.executeSql('DROP TABLE filedata;');
        }
    );
}
 
db.transaction(
    function (transaction) {
        transaction.executeSql('CREATE TABLE IF NOT EXISTS files(id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, filedata_id INTEGER NOT NULL, deleted INTEGER NOT NULL DEFAULT 0);', [], nullDataHandler, killTransaction);
        transaction.executeSql('CREATE TABLE IF NOT EXISTS filedata(id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, datablob BLOB NOT NULL DEFAULT "");', [], nullDataHandler, errorHandler);
    }
);
 
}
 
/*! When passed as the error handler, this silently causes a transaction to fail. */
function killTransaction(transaction, error)
{
    return true; // fatal transaction error
}
 
/*! When passed as the error handler, this causes a transaction to fail with a warning message. */
function errorHandler(transaction, error)
{
    // Error is a human-readable string.
    alert('Oops.  Error was '+error.message+' (Code '+error.code+')');
 
    // Handle errors here
    var we_think_this_error_is_fatal = true;
    if (we_think_this_error_is_fatal) return true;
    return false;
}
 
/*! This is used as a data handler for a request that should return no data. */
function nullDataHandler(transaction, results)
{
}
 
/*! This returns a string if you have not yet saved changes.  This is used by the onbeforeunload
    handler to warn you if you are about to leave the page with unsaved changes. */
function saveChangesDialog(event)
{
    var contentdiv = document.getElementById('contentdiv');
    var contents = contentdiv.contentDocument.body.innerHTML;
    var origcontentdiv = document.getElementById('origcontentdiv');
    var origcontents = origcontentdiv.innerHTML;
 
    // alert('close dialog');
 
    if (contents == origcontents) {
    return NULL;
    }
 
    return "You have unsaved changes."; //   CMP "+contents+" TO "+origcontents;
}
 
/*! This sets up an onbeforeunload handler to avoid accidentally navigating away from the
    page without saving changes. */
function setupEventListeners()
{
    window.onbeforeunload = function () {
    return saveChangesDialog();
    };
}