/*

File: JSheetDelegate.m

Abstract: Implementation file for the native side of the Sheets-in-Java example,

    using JAWT to attach a sheet to a Swing JFrame's NSWindow peer.

    See additional comments below, noting the asynchronous communication between

    AppKit and AWT.

Version: 1.1

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*/ 

#import "JSheetDelegate.h"

static JavaVM *jvm;

static jmethodID saveFinish_mID, openFinish_mID, cancel_mID;

static jclass jDelegateClass;

JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved) {

    jvm = vm;

    return JNI_VERSION_1_4;

}

// Cache all our callbacks at class-load time

// These may be invalidated if the Java class is unloaded, so we globalRef the class

// To get native signatures for Java methods:

//  % cd <build dir>

//  % javap -classpath JavaHeaders.jar -s apple.dts.samplecode.jsheets.JSheetDelegate

JNIEXPORT void JNICALL Java_apple_dts_samplecode_jsheets_JSheetDelegate_initMethodIDs (JNIEnv *env, jclass clazz) {

    jDelegateClass = (*env)->NewGlobalRef(env, clazz);

    saveFinish_mID = (*env)->GetStaticMethodID(env, clazz, "fireSaveSheetFinished", "(Lapple/dts/samplecode/jsheets/event/SaveSheetListener;Ljava/lang/String;)V");

    openFinish_mID = (*env)->GetStaticMethodID(env, clazz, "fireOpenSheetFinished", "(Lapple/dts/samplecode/jsheets/event/OpenSheetListener;[Ljava/lang/String;)V");

    cancel_mID = (*env)->GetStaticMethodID(env, clazz, "fireSheetCancelled", "(Lapple/dts/samplecode/jsheets/event/SheetListener;)V");  

}

// Determines whether the current thread is already attached to the VM,

// and tells the caller if it needs to later DetachCurrentThread 

//

// CALL THIS ONCE WITHIN A FUNCTION SCOPE and use a local boolean

// for mustDetach; if you do not, the first call might attach, setting 

// mustDetach to true, but the second will misleadingly set mustDetach 

// to false, leaving a dangling JNIEnv

jint GetJNIEnv(JNIEnv **env, bool *mustDetach) {

    jint getEnvErr = JNI_OK;

    *mustDetach = false;

    if (jvm) {

        getEnvErr = (*jvm)->GetEnv(jvm, (void **)env, JNI_VERSION_1_4);

        if (getEnvErr == JNI_EDETACHED) {

            getEnvErr = (*jvm)->AttachCurrentThread(jvm, (void **)env, NULL);

            if (getEnvErr == JNI_OK) {

                *mustDetach = true;

            }

        }

    }

    return getEnvErr;

}

/*

 * Class:     apple_dts_samplecode_jsheets_JSheetDelegate

 * Method:    nativeShowSheet

 * Signature: (ILjava/awt/Component;Lapple/dts/samplecode/jsheets/event/SheetListener;)V

 */

JNIEXPORT void JNICALL Java_apple_dts_samplecode_jsheets_JSheetDelegate_nativeShowSheet 

 (JNIEnv *env, jclass caller, jint type, jobject parent, jobject listener) { 

    // Never assume an AutoreleasePool is in place, unless you are on the main AppKit thread

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    JSheetDelegate *jdel;

    // Take the parent component (passed via Java call) and get the parent NSWindow from it

    NSWindow *parentWindow = GetWindowFromComponent(parent, env);

    // It is extremely important to show the sheet from the main AppKit thread WITHOUT BLOCKING using performSelectorOnMainThread with a waitUntilDone value of NO

    switch (type) {

        case apple_dts_samplecode_jsheets_JSheetDelegate_OPEN_PANEL:

            jdel = [JSheetDelegate delegateWithListener:listener env:env];

            // Bump the retain count on the delegate until the sheet goes away (i.e. openPanelDidEnd:)

            [jdel retain];

            [jdel performSelectorOnMainThread:@selector(showOpenPanelForWindow:) withObject:parentWindow waitUntilDone:NO];

            // DON'T DO THIS; AppKit operations off the main AppKit thread will likely hang or crash Cocoa

//          [jdel showOpenPanelForWindow:parentWindow];

            break;

        case apple_dts_samplecode_jsheets_JSheetDelegate_SAVE_PANEL:

            jdel = [JSheetDelegate delegateWithListener:listener env:env];

            // Bump the retain count on the delegate until the sheet goes away (i.e. savePanelDidEnd:)

            [jdel retain];

            [jdel performSelectorOnMainThread:@selector(showSavePanelForWindow:) withObject:parentWindow waitUntilDone:NO];

            break;

    }

    [pool release];

}

// Given a Java component, return an NSWindow*

NSWindow * GetWindowFromComponent(jobject parent, JNIEnv *env) {

    JAWT awt;

    JAWT_DrawingSurface* ds;

    JAWT_DrawingSurfaceInfo* dsi;

    JAWT_MacOSXDrawingSurfaceInfo* dsi_mac;

    jboolean result;

    jint lock;

    // Get the AWT

    awt.version = JAWT_VERSION_1_4;

    result = JAWT_GetAWT(env, &awt);

    assert(result != JNI_FALSE);

    // Get the drawing surface

    ds = awt.GetDrawingSurface(env, parent);

    assert(ds != NULL);

    // Lock the drawing surface

    lock = ds->Lock(ds);

    assert((lock & JAWT_LOCK_ERROR) == 0);

    // Get the drawing surface info

    dsi = ds->GetDrawingSurfaceInfo(ds);

    // Get the platform-specific drawing info

    dsi_mac = (JAWT_MacOSXDrawingSurfaceInfo*)dsi->platformInfo;

    // Get the NSView corresponding to the component that was passed

    NSView *view = dsi_mac->cocoaViewRef;

    // Free the drawing surface info

    ds->FreeDrawingSurfaceInfo(dsi);

    // Unlock the drawing surface

    ds->Unlock(ds);

    // Free the drawing surface

    awt.FreeDrawingSurface(ds);

    // Get the view's parent window; this is what we need to show a sheet

    return [view window];

}

@implementation JSheetDelegate

+ (id) delegateWithListener:(jobject)listener env:(JNIEnv *)env {

    return [[[JSheetDelegate alloc] initWithListener:listener env:env] autorelease];

}

- (id) initWithListener:(jobject)listener env:(JNIEnv*)env {    

    self = [super init];

    // Obtain a global ref to the Java listener for this sheet's results.

    // This prevents the listener from being GC'd until we are done with it

    sheetListener = (*env)->NewGlobalRef(env, listener);

    if (sheetListener == NULL) {

        NSLog(@"No memory available for JSheetDelegate GlobalRef");

        return nil;

    }

    return self;

}

// Given a Java-derived NSWindow, show an NSOpenPanel as a sheet

// Register a response selector so Java can be called back with the resulting filename

- (void) showOpenPanelForWindow:(NSWindow *)parentWindow {

    NSOpenPanel *op = [NSOpenPanel openPanel];

    [op setAllowsMultipleSelection:YES];

    [op beginSheetForDirectory:NSHomeDirectory() file:nil types:nil modalForWindow:parentWindow modalDelegate:self didEndSelector:@selector(openPanelDidEnd:returnCode:contextInfo:) contextInfo:nil];

}

// Same as above, only using NSSavePanel

- (void) showSavePanelForWindow:(NSWindow *)parentWindow {

    NSSavePanel *sp;

    // create or get the shared instance of NSSavePanel

    sp = [NSSavePanel savePanel];

    // set up new attributes 

    [sp setRequiredFileType:@"txt"];

    // display the NSSavePanel

    [sp beginSheetForDirectory:NSHomeDirectory() file:nil modalForWindow:parentWindow modalDelegate:self didEndSelector:@selector(savePanelDidEnd:returnCode:contextInfo:) contextInfo:nil];

}

// Delegate selector for openPanel selection

// Calls back to Java with result status: either cancellation or the path for a file to open

- (void) openPanelDidEnd:(NSOpenPanel *)sheet returnCode:(int)returnCode contextInfo:(void *)contextInfo {

    JNIEnv *env = NULL;

    bool shouldDetach = false;

    // Find out if we actually need to attach the current thread to obtain a JNIEnv, 

    // or if one is already in place

    // This will determine whether DetachCurrentThread should be called later

    if (GetJNIEnv(&env, &shouldDetach) != JNI_OK) {

        NSLog(@"savePanelDidEnd: could not attach to JVM");

        return;

    }

    // If we have file results, translate them to Java strings and tell the Java JSheetDelegate 

    // class to notify our listener

    if (returnCode == NSOKButton) {             

        NSEnumerator *files = [[sheet filenames] objectEnumerator];

        // init a jobjectArray with [[sheet filenames] count]

        jclass stringClass = (*env)->FindClass(env, "java/lang/String");

        jobjectArray jpaths = (*env)->NewObjectArray(env, [[sheet filenames] count], stringClass, NULL);

        NSString *nextFile;

        int javaIndex = 0;

        while (nextFile = (NSString *)[files nextObject]) {

            jsize buflen = [nextFile length];

            jchar buffer[buflen];

            [nextFile getCharacters:(unichar *)buffer];

            // fill the jobjectArray

            jstring js = (*env)->NewString(env, buffer, buflen);

            if (js == NULL) {

                NSLog(@"openPanelDidEnd: could not create jstring");

                return;

            }

            (*env)->SetObjectArrayElement(env, jpaths, javaIndex++, js);

            (*env)->DeleteLocalRef(env, js);

        }

        // Tell Java to notify the SheetListener

        if (openFinish_mID != NULL) {

            (*env)->CallStaticVoidMethod(env, jDelegateClass, openFinish_mID, sheetListener, jpaths);

        } else NSLog(@"openPanelDidEnd: bad mID");

        (*env)->DeleteLocalRef(env, jpaths);

        (*env)->DeleteLocalRef(env, stringClass);

    } else if (cancel_mID != NULL) {

        // Cancellation callback; Java will invoke sheetCancelled on our listener

        (*env)->CallStaticVoidMethod(env, jDelegateClass, cancel_mID, sheetListener);

    }

    // We're done with the listener; release the global ref

    (*env)->DeleteGlobalRef(env, sheetListener);

    // IMPORTANT: if GetJNIEnv attached for us, we need to detach when done

    if (shouldDetach) {

        (*jvm)->DetachCurrentThread(jvm);

    }

    // This delegate was was retained in nativeShowSheet; since this callback occurs on the AppKit thread,

    // which always has a pool in place, it can be autoreleased rather than released

    [self autorelease];

}

// Nearly identical to openPanelDidEnd, except savePanels only ever have a single filename 

- (void)savePanelDidEnd:(NSSavePanel *)sheet returnCode:(int)returnCode contextInfo:(void *)contextInfo {

    JNIEnv *env;

    bool shouldDetach = false;

    if (GetJNIEnv(&env, &shouldDetach) != JNI_OK) {

        NSLog(@"savePanelDidEnd: could not attach to JVM");

        return;

    }

    // Call back to Java if the user clicked Save

    if (returnCode == NSOKButton) {

        if (saveFinish_mID != NULL) {

            jsize buflength = [[sheet filename] length];

            jchar buffer[buflength];

            [[sheet filename] getCharacters:(unichar *)buffer];

            jstring str = (*env)->NewString(env, buffer, buflength);

            (*env)->CallStaticVoidMethod(env, jDelegateClass, saveFinish_mID, sheetListener, str);

            (*env)->DeleteLocalRef(env, str);

        } else NSLog(@"savePanelDidEnd: null Java methodID");

    } else if (cancel_mID != NULL) {

        (*env)->CallStaticVoidMethod(env, jDelegateClass, cancel_mID, sheetListener);

    }

    (*env)->DeleteGlobalRef(env, sheetListener);

    if (shouldDetach) {

        (*jvm)->DetachCurrentThread(jvm);

    }

    [self autorelease];

}

@end