Various export enhancements and fixes, including:

- A new SPExportFile class, providing an abstract interface to the handling and creation of export files.
- Enables the centralisation of all file/file handle creation logic as well as better support for handling situations where files fail to be created, including files that already exist at the export location.
- New SPExportFileHandleStatus constants to support the reporting of file handle creation.
- Update SPExporter to use the new file class instead of directly using an instance of SPFileHandle.
- Add the necessary logic to deal with files that already exist on disk, by providing the user with 3 options: cancel the export, ignore the files in question or overwrite them. We might want to enhance this to make new files sequential in name to prevent overwriting. Fixes issue #742.
- New SPExportFileUtilities category, which centralises all the logic relating to writing export type headers as well as dealing with problems occurred during file/file handle creation.
- Improve feedback given on the export progress sheet during export initialisation.
- Tidy up and improve comments.

1 files changed, 210 insertions, 0 deletions

diff --git a/Source/SPExportFile.m b/Source/SPExportFile.m
new file mode 100644
index 00000000..e102b28e
--- /dev/null
+++ b/Source/SPExportFile.m
@@ -0,0 +1,210 @@
+//
+//  $Id$
+//
+//  SPExportFile.m
+//  sequel-pro
+//
+//  Created by Stuart Connolly (stuconnolly.com) on July 31, 2010
+//  Copyright (c) 2010 Stuart Connolly. All rights reserved.
+//
+//  This program is free software; you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation; either version 2 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU General Public License for more details.
+//
+//  You should have received a copy of the GNU General Public License
+//  along with this program; if not, write to the Free Software
+//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//
+//  More info at <http://code.google.com/p/sequel-pro/>
+
+#import "SPExportFile.h"
+
+@interface SPExportFile (PrivateAPI)
+
+- (SPExportFileHandleStatus)_createFileHandle;
+
+@end
+
+@implementation SPExportFile
+
+@synthesize exportFilePath;
+@synthesize exportFileHandle;
+@synthesize exportFileNeedsCSVHeader;
+@synthesize exportFileNeedsXMLHeader;
+@synthesize exportFileHandleStatus;
+
+#pragma mark -
+#pragma mark Initialization
+
+/**
+ * Initialise an autoreleased instance of SPExport using the supplied path.
+ *
+ * @param path The path of the export file
+ *
+ * @return The initialised instance
+ */
++ (SPExportFile *)exportFileAtPath:(NSString *)path
+{
+	return [[[SPExportFile alloc] initWithFilePath:path] autorelease];
+}
+
+/**
+ * Initialise an instance of SPExportFile using the supplied path.
+ *
+ * @param path The path of the export file
+ *
+ * @return The initialised instance
+ */
+- (id)initWithFilePath:(NSString *)path
+{
+	if ((self = [super init])) {
+		
+		[self setExportFilePath:path];
+		
+		exportFileHandleStatus = -1;
+		
+		[self setExportFileNeedsCSVHeader:NO];
+		[self setExportFileNeedsXMLHeader:NO];
+	}
+	
+	return self;
+}
+
+#pragma mark -
+#pragma mark General Methods
+
+/**
+ * Closes the export file to writing.
+ */
+- (void)close
+{
+	if (![self exportFileHandle]) return;
+	
+	[[self exportFileHandle] closeFile];
+}
+
+/**
+ * Deletes the export file on disk.
+ *
+ * @return A BOOL indicating the success of attempting to delete the file
+ */
+- (BOOL)delete
+{
+	if ((![self exportFilePath]) || (![self exportFileHandle]) || ([[self exportFilePath] length] == 0)) return NO;
+	
+	NSFileManager *fileManager = [NSFileManager defaultManager];
+	
+	if ([fileManager fileExistsAtPath:[self exportFilePath]]) {
+		return [[NSFileManager defaultManager] removeItemAtPath:[self exportFilePath] error:nil];
+	}
+}
+
+/**
+ * This is a convenience method provided in order to write the supplied data to the underlying filehandle
+ * without having to directly access it. Throws an exception if attempting to write data when no file 
+ * handle exists.
+ *
+ * @param data The data to be written
+ */
+- (void)writeData:(NSData *)data
+{
+	if (![self exportFileHandle]) {
+		[NSException raise:NSInternalInconsistencyException format:@"Attempting to write to an uninitialized file handle."];
+		
+		return;
+	}
+			
+	[[self exportFileHandle] writeData:data];
+}
+
+/**
+ * Creates the underlying export file handle and thus the actual file on disk.
+ *
+ * @param overwrite If true and a file already exists at this file's location, then it'll be overwritten.
+ * 
+ * @return One of SPExportFileHandleStatus indicating the status of its creation.
+ */
+- (SPExportFileHandleStatus)createExportFileHandle:(BOOL)overwrite
+{
+	// The file path must be set before attempting to create the file handle
+	if ((![self exportFilePath]) || ([[self exportFilePath] length] == 0)) {
+		[NSException raise:NSInternalInconsistencyException 
+					format:@"Attempting to create an export filehandle for a path that is either not set or has zero length: %@." 
+				 arguments:[self exportFilePath]];
+		
+		return;
+	}
+	
+	NSFileManager *fileManager = [NSFileManager defaultManager];
+		
+	if ([fileManager fileExistsAtPath:[self exportFilePath]]) {
+		
+		// If specified attempt to overwrite the file
+		if (overwrite) {
+			// Check that it's writable first
+			if ([fileManager isWritableFileAtPath:[self exportFilePath]]) {
+				exportFileHandleStatus = [self _createFileHandle];
+			}
+			// The file is not writable, so return that we failed.
+			else {
+				exportFileHandleStatus = SPExportFileHandleFailed;
+			}
+		}
+		else {
+			exportFileHandleStatus = SPExportFileHandleExists;
+		}
+	} 
+	// Otherwise attempt to create a file
+	else {
+		exportFileHandleStatus = [self _createFileHandle];
+	}
+	
+	return exportFileHandleStatus;
+}
+
+#pragma mark -
+#pragma mark Private API
+
+/**
+ * Creates the actual empty file handle and establishes a file handle to it.
+ *
+ * @return The status of the file handle's creation. See SPExportFileHandleStatus constants.
+ */
+- (SPExportFileHandleStatus)_createFileHandle
+{
+	NSFileManager *fileManager = [NSFileManager defaultManager];
+	
+	if (![fileManager createFileAtPath:[self exportFilePath] contents:[NSData data] attributes:nil]) {
+		return SPExportFileHandleFailed;
+	}
+	
+	// Retrieve a filehandle for the file, attempting to delete it on failure.
+	exportFileHandle = [[SPFileHandle fileHandleForWritingAtPath:[self exportFilePath]] retain];
+	
+	if (!exportFileHandle) {
+		[[NSFileManager defaultManager] removeFileAtPath:[self exportFilePath] handler:nil];
+		
+		return SPExportFileHandleFailed;
+	}
+	
+	return SPExportFileHandleCreated;
+}
+
+#pragma mark -
+#pragma mark Other
+
+/**
+ * Dealloc.
+ */
+- (void)dealloc
+{
+	if (exportFileHandle) [exportFileHandle release], exportFileHandle = nil; 
+}
+
+@end