/* Copyright (c) 1011 Sven Weidauer
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#import "BlackScroller.h"

@implementation BlackScroller

- (void)setFrame:(NSRect)frameRect
{
    [super setFrame:frameRect];
    if (tag != 0)
        [self removeTrackingRect:tag];
    tag = [self addTrackingRect:[self bounds] owner:self userData:NULL assumeInside:NO];
}

- (void)drawRect:(NSRect)dirtyRect
{
    [[NSColor clearColor] set];
    [NSBezierPath fillRect:dirtyRect];

    if (drawTrack)
        [self drawKnobSlotInRect:[self rectForPart:NSScrollerKnobSlot]
                       highlight:NO];
    [self drawKnob];
}

- (void)drawKnobSlotInRect:(NSRect)slotRect highlight:(BOOL)flag
{
    slotRect = NSInsetRect(slotRect, 2, 2);
    slotRect = [self.window convertRectToScreen:slotRect];
    slotRect.origin.x = floor(slotRect.origin.x) + 0.5;
    slotRect.origin.y = floor(slotRect.origin.y) + 0.5;
    slotRect.size.width = floor(slotRect.size.width);
    slotRect.size.height = floor(slotRect.size.height);
    slotRect = [self.window convertRectFromScreen:slotRect];

    NSGradient *gradient = [[NSGradient alloc] initWithColorsAndLocations:
                                                   [NSColor clearColor], 0.0,
                                               [NSColor clearColor], 0.4,
                                               [NSColor whiteColor], 1.0,
                                               nil];
    [[NSColor whiteColor] set];
    const float radius = 0.5 * ([self isHorizontal] ? NSHeight(slotRect) : NSWidth(slotRect));
    NSBezierPath *path = [NSBezierPath bezierPathWithRoundedRect:slotRect
                                                         xRadius:radius
                                                         yRadius:radius];
    [gradient drawInBezierPath:path angle:[self isHorizontal] ? 90 : 0];

    [path stroke];
}

- (NSUsableScrollerParts)usableParts
{
    return NSScrollerKnob | NSScrollerKnobSlot;
}

- (void)drawKnob
{
    NSRect rect = NSInsetRect([self rectForPart:NSScrollerKnob], 2, 2);

    rect = [self.window convertRectToScreen:rect];
    rect.origin.x = floor(rect.origin.x) + 0.5;
    rect.origin.y = floor(rect.origin.y) + 0.5;
    rect.size.width = floor(rect.size.width);
    rect.size.height = floor(rect.size.height);
    rect = [self.window convertRectFromScreen:rect];

    [[NSColor colorWithDeviceWhite:1.0 alpha:drawTrack ? 1.0 : 0.6] set];

    const float radius = 0.5 * ([self isHorizontal] ? NSHeight(rect) : NSWidth(rect));
    NSBezierPath *path = [NSBezierPath bezierPathWithRoundedRect:rect
                                                         xRadius:radius
                                                         yRadius:radius];
    [path fill];
    [path stroke];
}

- (NSRect)rectForPart:(NSScrollerPart)partCode
{
    const bool horizontal = [self isHorizontal];

    NSRect rect = horizontal ? NSInsetRect([self bounds], 4, 0) : NSInsetRect([self bounds], 0, 4);

    switch (partCode) {
    case NSScrollerKnobSlot:
        return rect;

    case NSScrollerKnob: {
        const CGFloat len = horizontal ? NSWidth(rect) : NSHeight(rect);
        CGFloat knobLen = [self knobProportion] * len;
        const CGFloat minKnobLen = horizontal ? NSHeight(rect) : NSWidth(rect);
        if (knobLen < minKnobLen)
            knobLen = minKnobLen;

        const CGFloat start = [self doubleValue] * (len - knobLen);

        if (horizontal) {
            rect.origin.x += start;
            rect.size.width = knobLen;
        } else {
            rect.origin.y += start;
            rect.size.height = knobLen;
        }

        return rect;
    }

    default:
        return [super rectForPart:partCode];
    }
}

- (BOOL)isOpaque
{
    return NO;
}

- (BOOL)isHorizontal
{
    NSRect bounds = [self bounds];
    return NSWidth(bounds) > NSHeight(bounds);
}

- (void)mouseEntered:(NSEvent *)theEvent
{
    drawTrack = YES;
    [self setNeedsDisplay:YES];
}

- (void)mouseExited:(NSEvent *)theEvent
{
    drawTrack = NO;
    [self setNeedsDisplay:YES];
}

@end