/*

     File: TCallScript.m 

 Abstract: A class for calling through from Objective-C to AppleScript handlers. 

  Version: 1.1 

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 */

#import "TCallScript.h"

#import "AEDescUtils.h"

#import <Carbon/Carbon.h>

#import <stdarg.h>

@implementation TCallScript

    /* initialized a TCallScript loading a pre-compiled script

    containing the handlers we wish to call */

- (id) initWithURLToCompiledScript:(NSURL*)scriptURL {

    self = [super init];

    if (self) {

        NSDictionary* errorInfo;

            /* load the compiled version of our AppleScript from the file AttachedScripts.scpt

            in the resources folder.  This script contains all of the handlers we will

            be using in this application.  */

        self.theScript = [[[NSAppleScript alloc] initWithContentsOfURL:scriptURL error:&errorInfo] autorelease];

    }

    return self;

}

- (void) dealloc {

    self.theScript = nil;

    [super dealloc];

}

    /* the following two routines are accessor methods for getting/setting

    the theScript field in our object.  Note that unlike the canonical

    way of implementing these routines we do not perform a copy when

    setting the theScript filed.  This is because the implementation of

    NSAppleScript does not allow you to do that. */

@synthesize theScript;

    /* callScript is the main workhorse routine we use for calling handlers

    in our AppleScript.  Essentially, this routine creates a 'call subroutine' Apple event

    and then it dispatches the event to the compiled AppleScript we loaded in our awakeFromNib

    routine. */

- (NSAppleEventDescriptor*) callScript:(NSString *)handlerName 

            withArrayOfParameters:(NSAppleEventDescriptor*) parameterList {

    ProcessSerialNumber PSN = {0, kCurrentProcess};

    NSAppleEventDescriptor *theAddress;

    NSAppleEventDescriptor *theEvent;

    NSAppleEventDescriptor* theHandlerName;

    NSDictionary *errorInfo;

    NSAppleEventDescriptor *theResult;

    /* create the target address descriptor specifying our own process as the target */

    theAddress = [NSAppleEventDescriptor descriptorWithDescriptorType:typeProcessSerialNumber 

                                                                bytes:&PSN length:sizeof(PSN)];

    if ( !theAddress )

    {

        NSRunAlertPanel(@"AttachAScript Error", @"Failed to create target address descriptor.", @"ok", nil, nil);

        return nil;

    }

    /* create a new Apple event of type typeAppleScript/kASSubroutineEvent */

    theEvent = [NSAppleEventDescriptor appleEventWithEventClass:typeAppleScript 

                                            eventID:kASSubroutineEvent targetDescriptor:theAddress 

                                            returnID:kAutoGenerateReturnID transactionID:kAnyTransactionID];

    if ( !theEvent )

    {

        NSRunAlertPanel(@"AttachAScript Error", @"Failed to create subroutine descriptor.", @"ok", nil, nil);

        return nil;

    }

    /* create a descriptor containing the handler's name.  AppleScript handler

        names must be converted to lowercase before including them in a call

        subroutine Apple event.  */

    theHandlerName = [NSAppleEventDescriptor descriptorWithString:[handlerName lowercaseString]];

    if ( !theHandlerName )

    {

        NSRunAlertPanel(@"AttachAScript Error", @"Failed to create handler name descriptor.", @"ok", nil, nil);

        return nil;

    }

    /* add the handler's name to the Apple event using the keyASSubroutineName keyword */

    [theEvent setDescriptor:theHandlerName forKeyword:keyASSubroutineName];

    /* add the parameter list.  If none was specified, then create an empty one */

    if ( parameterList != nil ) {

        [theEvent setDescriptor:parameterList forKeyword:keyDirectObject];

    } else {

        NSAppleEventDescriptor* paramList = [NSAppleEventDescriptor listDescriptor];

        [theEvent setDescriptor:paramList forKeyword:keyDirectObject];

    }

    /* send the subroutine event to the script  */

    theResult = [[self theScript] executeAppleEvent:theEvent error:&errorInfo];

    /* if an error happened in the AppleScript, display the error information.  */

    if ( nil == theResult ) {

        NSString* paramStr;

        /* collect the parameters into a string of comma separated values

            so the user can see what they are */

        if ( parameterList != nil ) {

                        NSArray* theParamStrings = [parameterList listOfStringsToArray];

                        paramStr = [theParamStrings componentsJoinedByString:@", "];

        } else {

                        paramStr = @"";

        }

        /* create the error message string */

        NSString *err = [NSString stringWithFormat:

                            @"Error %@ occured the %@(%@) call: %@",

                            [errorInfo objectForKey:NSAppleScriptErrorNumber],

                            handlerName, paramStr,

                            [errorInfo objectForKey:NSAppleScriptErrorBriefMessage]];

        /* display an alert panel showing the error */

        NSRunAlertPanel(@"AttachAScript Error", err, @"ok", nil, nil);

        return nil;

    }

    /* return whatever result the script returned */

    return theResult;

}

    /* callHandler is a convenience routine that calls through to

    callScript:withArrayOfParameters:.  This method received parameters

    as a variable argument list of Objective-C objects and it automatically

    builds the AEDescList parameter for callScript:withArrayOfParameters: based

    on the types of objects provided as parameters.  Parameters may be NSNumbers,

    NSStrings, or NSAppleEventDescriptors.  */

- (NSAppleEventDescriptor*) callHandler:(NSString *)handlerName withParameters: (id) firstParameter, ... {

    va_list args;

    int index = 1;

    id nthID;

    NSAppleEventDescriptor* paramList = [NSAppleEventDescriptor listDescriptor];

    va_start(args, firstParameter);

    for (nthID=firstParameter; nthID != nil; nthID = va_arg(args, id) ) {

        if ( [nthID isKindOfClass: [NSNumber class]] ) {

            [paramList insertDescriptor:

                    [NSAppleEventDescriptor descriptorWithInt32:[nthID longValue]] atIndex:(index++)];

        } else if ( [nthID isKindOfClass: [NSString class]] ) {

            [paramList insertDescriptor:

                    [NSAppleEventDescriptor descriptorWithString:nthID] atIndex:(index++)];

        } else if ( [nthID isKindOfClass: [NSAppleEventDescriptor class]] ) {

            [paramList insertDescriptor: nthID atIndex:(index++)];

        } else {

            NSLog(@"unrecognized parameter type for parameter %d in callHandler:withParameters:", index);

            return nil; /* bad parameter */

        }

    }

    va_end(args);

    return [self callScript: handlerName withArrayOfParameters: paramList];

}

@end