//
//  History.m
//  RCocoaBundle
//
//  Created by Simon Urbanek on Sat Mar 06 2004.
//  Copyright (c) 2004 R Development Core Team. All rights reserved.
//

#import "History.h"


@implementation History
/** implements a history with one dirt entry (i.e. an entry which is still being edited but not cimmited yet) */

- (id) init {
    hist = [[NSMutableArray alloc] initWithCapacity: 16];
    dirtyEntry=nil;
    pos=0;
    return self;
}

- (void) dealloc {
    [self resetAll];
    [hist release];
    [super dealloc];
}

/** commits an entry to the end of the history, except it equals to the last entry; moves the current position past the last entry and also deletes any dirty entry */
- (void) commit: (NSString*) entry {
    int ac = [hist count];
    if (ac==0 || ![[hist objectAtIndex: ac-1] isEqualToString:entry]) { // only add if it's not equal to the last one
        [hist addObject: entry];
    }
    if (dirtyEntry!=nil) [dirtyEntry release];
    dirtyEntry=nil;
    pos=[hist count];
}

/** moves to the next entry; if out of the history, returns the dirty entry */
- (NSString*) next {
    int ac = [hist count];
    if (pos<ac) {
        pos++;
        if (pos<ac) return (NSString*) [hist objectAtIndex: pos];
    }
    // we're past the history, always return the dirty entry
    return dirtyEntry;
}

/** moves to the previous entry; if past the beginning, returns nil */
- (NSString*) prev {
    if (pos>0) { pos--; return (NSString*) [hist objectAtIndex: pos]; };
    return nil;
}

/** returns the current entry (can be the dirty entry, too) */
- (NSString*) current {
    int ac = [hist count];
    if (pos<ac) return (NSString*) [hist objectAtIndex: pos];
    return dirtyEntry;
}

/** returns YES if the current position is in the dirty entry */
- (BOOL) isDirty {
    return (pos==[hist count])?YES:NO;
}

/** updates the dirty entry with teh passed string, iff we're currently in the dirty position */
- (void) updateDirty: (NSString*) entry {
    if (pos==[hist count]) {
        if (entry==dirtyEntry) return;
        if (dirtyEntry!=nil) [dirtyEntry release];
        dirtyEntry=(entry==nil)?nil:[entry copy];
    }
}

/** resets the entire history, position and ditry entry */
- (void) resetAll {
    [hist removeAllObjects];
    if (dirtyEntry!=nil) [dirtyEntry release];
    pos=0;
}

/** returns a snapshot of the current histroy (w/o the dirty entry). you will need to release the resulting object. */
- (NSArray*) entries {
    return [NSArray arrayWithArray: hist];
}

@end