//
//  CSCathodeRayView.m
//  CLK
//
//  Created by Thomas Harte on 16/07/2015.
//  Copyright © 2015 Thomas Harte. All rights reserved.
//

#import "CSCathodeRayView.h"
@import CoreVideo;
@import GLKit;
#import <OpenGL/gl3.h>
#import <OpenGL/gl3ext.h>
#import <libkern/OSAtomic.h>


@implementation CSCathodeRayView {
	CVDisplayLinkRef displayLink;

	GLuint _vertexShader, _fragmentShader;
	GLuint _shaderProgram;
	GLuint _arrayBuffer, _vertexArray;
	GLint _positionAttribute;
	GLint _textureCoordinatesAttribute;
	GLint _lateralAttribute;

	GLint _textureSizeUniform, _windowSizeUniform;
	GLint _boundsOriginUniform, _boundsSizeUniform;
	GLint _alphaUniform;

	GLuint _textureName, _shadowMaskTextureName;
	CRTSize _textureSize;

	CRTFrame *_crtFrame;

	NSString *_signalDecoder;
	CSCathodeRayViewSignalType _signalType;
	int32_t _signalDecoderGeneration;
	int32_t _compiledSignalDecoderGeneration;
}

- (GLuint)textureForImageNamed:(NSString *)name
{
	NSImage *const image = [NSImage imageNamed:name];
	NSBitmapImageRep *bitmapRepresentation = [[NSBitmapImageRep alloc] initWithData: [image TIFFRepresentation]];

	GLuint textureName;
	glGenTextures(1, &textureName);
	glBindTexture(GL_TEXTURE_2D, textureName);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, (GLsizei)image.size.width, (GLsizei)image.size.height, 0, GL_RGB, GL_UNSIGNED_BYTE, bitmapRepresentation.bitmapData);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glGenerateMipmap(GL_TEXTURE_2D);

	return textureName;
}

- (void)prepareOpenGL
{
	// Synchronize buffer swaps with vertical refresh rate
	GLint swapInt = 1;
	[[self openGLContext] setValues:&swapInt forParameter:NSOpenGLCPSwapInterval];

	// Create a display link capable of being used with all active displays
	CVDisplayLinkCreateWithActiveCGDisplays(&displayLink);
 
	// Set the renderer output callback function
	CVDisplayLinkSetOutputCallback(displayLink, DisplayLinkCallback, (__bridge void * __nullable)(self));
 
	// Set the display link for the current renderer
	CGLContextObj cglContext = [[self openGLContext] CGLContextObj];
	CGLPixelFormatObj cglPixelFormat = [[self pixelFormat] CGLPixelFormatObj];
	CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(displayLink, cglContext, cglPixelFormat);

	// install the shadow mask texture as the second texture
	glActiveTexture(GL_TEXTURE1);
	_shadowMaskTextureName = [self textureForImageNamed:@"ShadowMask"];

	// otherwise, we'll be working on the first texture
	glActiveTexture(GL_TEXTURE0);

	// get the shader ready, set the clear colour
	[self.openGLContext makeCurrentContext];
	glClearColor(0.0, 0.0, 0.0, 1.0);

	// Activate the display link
	CVDisplayLinkStart(displayLink);

	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE);
}

static CVReturn DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeStamp *now, const CVTimeStamp *outputTime, CVOptionFlags flagsIn, CVOptionFlags *flagsOut, void *displayLinkContext)
{
	CSCathodeRayView *view = (__bridge CSCathodeRayView *)displayLinkContext;
	[view.delegate openGLView:view didUpdateToTime:*now];
	return kCVReturnSuccess;
}

- (void)invalidate
{
	CVDisplayLinkStop(displayLink);
}

- (void)dealloc
{
	// Release the display link
	CVDisplayLinkRelease(displayLink);

	// Release OpenGL buffers
	[self.openGLContext makeCurrentContext];
	glDeleteBuffers(1, &_arrayBuffer);
	glDeleteVertexArrays(1, &_vertexArray);
	glDeleteTextures(1, &_textureName);
	glDeleteTextures(1, &_shadowMaskTextureName);
	glDeleteProgram(_shaderProgram);
}

- (NSPoint)backingViewSize
{
	NSPoint backingSize = {.x = self.bounds.size.width, .y = self.bounds.size.height};
	return [self convertPointToBacking:backingSize];
}

- (void)reshape
{
	[super reshape];

	[self.openGLContext makeCurrentContext];
	CGLLockContext([[self openGLContext] CGLContextObj]);

	NSPoint viewSize = [self backingViewSize];
	glViewport(0, 0, (GLsizei)viewSize.x, (GLsizei)viewSize.y);

	[self pushSizeUniforms];

	CGLUnlockContext([[self openGLContext] CGLContextObj]);
}

- (void)setFrameBounds:(CGRect)frameBounds
{
	_frameBounds = frameBounds;

	[self.openGLContext makeCurrentContext];
	CGLLockContext([[self openGLContext] CGLContextObj]);

	[self pushSizeUniforms];

	CGLUnlockContext([[self openGLContext] CGLContextObj]);
}

- (void)pushSizeUniforms
{
	if(_shaderProgram)
	{
		if(_windowSizeUniform >= 0)
		{
			NSPoint viewSize = [self backingViewSize];
			glUniform2f(_windowSizeUniform, (GLfloat)viewSize.x, (GLfloat)viewSize.y);
		}

		if(_boundsOriginUniform >= 0) glUniform2f(_boundsOriginUniform, (GLfloat)_frameBounds.origin.x, (GLfloat)_frameBounds.origin.y);
		if(_boundsSizeUniform >= 0) glUniform2f(_boundsSizeUniform, (GLfloat)_frameBounds.size.width, (GLfloat)_frameBounds.size.height);
	}
}

- (void)awakeFromNib
{
	NSOpenGLPixelFormatAttribute attributes[] =
	{
		NSOpenGLPFADoubleBuffer,
		NSOpenGLPFAOpenGLProfile,	NSOpenGLProfileVersion3_2Core,
		NSOpenGLPFASampleBuffers,	1,
		NSOpenGLPFASamples,			2,
		0
	};

	NSOpenGLPixelFormat *pixelFormat = [[NSOpenGLPixelFormat alloc] initWithAttributes:attributes];
	NSOpenGLContext *context = [[NSOpenGLContext alloc] initWithFormat:pixelFormat shareContext:nil];

#ifdef DEBUG
	// When we're using a CoreProfile context, crash if we call a legacy OpenGL function
	// This will make it much more obvious where and when such a function call is made so
	// that we can remove such calls.
	// Without this we'd simply get GL_INVALID_OPERATION error for calling legacy functions
	// but it would be more difficult to see where that function was called.
	CGLEnable([context CGLContextObj], kCGLCECrashOnRemovedFunctions);
#endif

	self.pixelFormat = pixelFormat;
	self.openGLContext = context;
	self.wantsBestResolutionOpenGLSurface = YES;

	// establish default instance variable values
	self.frameBounds = CGRectMake(0.0, 0.0, 1.0, 1.0);
}

- (GLint)formatForDepth:(unsigned int)depth
{
	switch(depth)
	{
		default: return -1;
		case 1: return GL_RED;
		case 2: return GL_RG;
		case 3: return GL_RGB;
		case 4: return GL_RGBA;
	}
}

- (BOOL)pushFrame:(nonnull CRTFrame *)crtFrame
{
	[[self openGLContext] makeCurrentContext];
	CGLLockContext([[self openGLContext] CGLContextObj]);

	BOOL hadFrame = _crtFrame ? YES : NO;
	_crtFrame = crtFrame;

	glBufferData(GL_ARRAY_BUFFER, _crtFrame->number_of_runs * kCRTSizeOfVertex * 6, _crtFrame->runs, GL_DYNAMIC_DRAW);

	glBindTexture(GL_TEXTURE_2D, _textureName);
	if(_textureSize.width != _crtFrame->size.width || _textureSize.height != _crtFrame->size.height)
	{
		GLint format = [self formatForDepth:_crtFrame->buffers[0].depth];
		glTexImage2D(GL_TEXTURE_2D, 0, format, _crtFrame->size.width, _crtFrame->size.height, 0, (GLenum)format, GL_UNSIGNED_BYTE, _crtFrame->buffers[0].data);
		_textureSize = _crtFrame->size;
	}
	else
		glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, _crtFrame->size.width, _crtFrame->dirty_size.height, (GLenum)[self formatForDepth:_crtFrame->buffers[0].depth], GL_UNSIGNED_BYTE, _crtFrame->buffers[0].data);

	[self drawView];

	CGLUnlockContext([[self openGLContext] CGLContextObj]);

	return hadFrame;
}

#pragma mark - Frame output

#if defined(DEBUG)
- (void)logErrorForObject:(GLuint)object
{
	GLint isCompiled = 0;
	glGetShaderiv(object, GL_COMPILE_STATUS, &isCompiled);
	if(isCompiled == GL_FALSE)
	{
		GLint logLength;
		glGetShaderiv(object, GL_INFO_LOG_LENGTH, &logLength);
		if (logLength > 0) {
			GLchar *log = (GLchar *)malloc((size_t)logLength);
			glGetShaderInfoLog(object, logLength, &logLength, log);
			NSLog(@"Compile log:\n%s", log);
			free(log);
		}
	}
}
#endif

- (GLuint)compileShader:(const char *)source type:(GLenum)type
{
	GLuint shader = glCreateShader(type);
	glShaderSource(shader, 1, &source, NULL);
	glCompileShader(shader);

#ifdef DEBUG
	[self logErrorForObject:shader];
#endif

	return shader;
}

- (void)setSignalDecoder:(nonnull NSString *)signalDecoder type:(CSCathodeRayViewSignalType)type
{
	_signalType	= type;
	_signalDecoder = [signalDecoder copy];
	OSAtomicIncrement32(&_signalDecoderGeneration);
}

- (nonnull NSString *)vertexShaderForType:(CSCathodeRayViewSignalType)type
{
	// the main job of the vertex shader is just to map from an input area of [0,1]x[0,1], with the origin in the
	// top left to OpenGL's [-1,1]x[-1,1] with the origin in the lower left, and to convert input data coordinates
	// from integral to floating point; there's also some setup for NTSC, PAL or whatever.

	NSString *const ntscVertexShaderGlobals =
		@"out vec2 srcCoordinatesVarying[4];\n"
		"out float phase;\n";

	NSString *const ntscVertexShaderBody =
		@"phase = srcCoordinates.x * 6.283185308;\n"
		"\n"
		"srcCoordinatesVarying[0] = vec2(srcCoordinates.x / textureSize.x, (srcCoordinates.y + 0.5) / textureSize.y);\n"
		"srcCoordinatesVarying[3] = srcCoordinatesVarying[0] + vec2(0.375 / textureSize.x, 0.0);\n"
		"srcCoordinatesVarying[2] = srcCoordinatesVarying[0] + vec2(0.125 / textureSize.x, 0.0);\n"
		"srcCoordinatesVarying[1] = srcCoordinatesVarying[0] - vec2(0.125 / textureSize.x, 0.0);\n"
		"srcCoordinatesVarying[0] = srcCoordinatesVarying[0] - vec2(0.325 / textureSize.x, 0.0);\n";

	NSString *const rgbVertexShaderGlobals =
		@"out vec2 srcCoordinatesVarying;\n";

	NSString *const rgbVertexShaderBody =
		@"srcCoordinatesVarying = vec2(srcCoordinates.x / textureSize.x, (srcCoordinates.y + 0.5) / textureSize.y);\n";

	NSString *const vertexShader =
		@"#version 150\n"
		"\n"
		"in vec2 position;\n"
		"in vec2 srcCoordinates;\n"
		"in float lateral;\n"
		"\n"
		"uniform vec2 boundsOrigin;\n"
		"uniform vec2 boundsSize;\n"
		"\n"
		"out float lateralVarying;\n"
		"out vec2 shadowMaskCoordinates;\n"
		"\n"
		"uniform vec2 textureSize;\n"
		"\n"
		"const float shadowMaskMultiple = 600;\n"
		"\n"
		"%@\n"
		"void main (void)\n"
		"{\n"
			"lateralVarying = lateral + 1.0707963267949;\n"
			"\n"
			"shadowMaskCoordinates = position * vec2(shadowMaskMultiple, shadowMaskMultiple * 0.85057471264368);\n"
			"\n"
			"%@\n"
			"\n"
			"vec2 mappedPosition = (position - boundsOrigin) / boundsSize;"
			"gl_Position = vec4(mappedPosition.x * 2.0 - 1.0, 1.0 - mappedPosition.y * 2.0, 0.0, 1.0);\n"
		"}\n";

// + mappedPosition.x / 131.0

	switch(_signalType)
	{
		case CSCathodeRayViewSignalTypeNTSC: return [NSString stringWithFormat:vertexShader, ntscVertexShaderGlobals, ntscVertexShaderBody];
		case CSCathodeRayViewSignalTypeRGB:	 return [NSString stringWithFormat:vertexShader, rgbVertexShaderGlobals, rgbVertexShaderBody];
	}
}

- (nonnull NSString *)fragmentShaderForType:(CSCathodeRayViewSignalType)type
{
	NSString *const fragmentShader =
		@"#version 150\n"
		"\n"
		"in float lateralVarying;\n"
		"in vec2 shadowMaskCoordinates;\n"
		"out vec4 fragColour;\n"
		"\n"
		"uniform sampler2D texID;\n"
		"uniform sampler2D shadowMaskTexID;\n"
		"uniform float alpha;\n"
		"\n"
		"%@\n"
		"%%@\n"
		"\n"
		"void main(void)\n"
		"{\n"
			"%@\n"
		"}\n";

	NSString *const ntscFragmentShaderGlobals =
		@"in vec2 srcCoordinatesVarying[4];\n"
		"in float phase;\n"
		"\n"
		"// for conversion from i and q are in the range [-0.5, 0.5] (so i needs to be multiplied by 1.1914 and q by 1.0452)\n"
		"const mat3 yiqToRGB = mat3(1.0, 1.0, 1.0, 1.1389784, -0.3240608, -1.3176884, 0.6490692, -0.6762444, 1.7799756);\n";

	NSString *const ntscFragmentShaderBody =
		@"vec4 angles = vec4(phase) + vec4(-2.35619449019234, -0.78539816339745, 0.78539816339745, 2.35619449019234);\n"
		"vec4 samples = vec4("
		"   sample(srcCoordinatesVarying[0], angles.x),"
		"	sample(srcCoordinatesVarying[1], angles.y),"
		"	sample(srcCoordinatesVarying[2], angles.z),"
		"	sample(srcCoordinatesVarying[3], angles.w)"
		");\n"
		"\n"
		"float y = dot(vec4(0.25), samples);\n"
		"samples -= vec4(y);\n"
		"\n"
		"float i = dot(cos(angles), samples);\n"
		"float q = dot(sin(angles), samples);\n"
		"\n"
		"fragColour = 5.0 * texture(shadowMaskTexID, shadowMaskCoordinates) * vec4(yiqToRGB * vec3(y, i, q), 1.0);//sin(lateralVarying));\n";

	NSString *const rgbFragmentShaderGlobals =
		@"in vec2 srcCoordinatesVarying;\n"; // texture(shadowMaskTexID, shadowMaskCoordinates) *

	NSString *const rgbFragmentShaderBody =
		@"fragColour = sample(srcCoordinatesVarying);//sin(lateralVarying));\n";

	switch(_signalType)
	{
		case CSCathodeRayViewSignalTypeNTSC: return [NSString stringWithFormat:fragmentShader, ntscFragmentShaderGlobals, ntscFragmentShaderBody];
		case CSCathodeRayViewSignalTypeRGB:	 return [NSString stringWithFormat:fragmentShader, rgbFragmentShaderGlobals, rgbFragmentShaderBody];
	}
}

- (void)prepareShader
{
	if(_shaderProgram)
	{
		glDeleteProgram(_shaderProgram);
		glDeleteShader(_vertexShader);
		glDeleteShader(_fragmentShader);
	}

	if(!_signalDecoder)
		return;

	NSString *const vertexShader = [self vertexShaderForType:_signalType];
	NSString *const fragmentShader = [self fragmentShaderForType:_signalType];

	_shaderProgram = glCreateProgram();
	_vertexShader = [self compileShader:[vertexShader UTF8String] type:GL_VERTEX_SHADER];
	_fragmentShader = [self compileShader:_signalDecoder ?
							[[NSString stringWithFormat:fragmentShader, _signalDecoder] UTF8String] :
							[fragmentShader UTF8String]
						type:GL_FRAGMENT_SHADER];

	glAttachShader(_shaderProgram, _vertexShader);
	glAttachShader(_shaderProgram, _fragmentShader);
	glLinkProgram(_shaderProgram);

#ifdef DEBUG
//	[self logErrorForObject:_shaderProgram];
#endif

	glGenVertexArrays(1, &_vertexArray);
	glBindVertexArray(_vertexArray);
	glGenBuffers(1, &_arrayBuffer);
	glBindBuffer(GL_ARRAY_BUFFER, _arrayBuffer);

	glUseProgram(_shaderProgram);

	_positionAttribute				= glGetAttribLocation(_shaderProgram, "position");
	_textureCoordinatesAttribute	= glGetAttribLocation(_shaderProgram, "srcCoordinates");
	_lateralAttribute				= glGetAttribLocation(_shaderProgram, "lateral");
	_alphaUniform					= glGetUniformLocation(_shaderProgram, "alpha");
	_textureSizeUniform				= glGetUniformLocation(_shaderProgram, "textureSize");
	_windowSizeUniform				= glGetUniformLocation(_shaderProgram, "windowSize");
	_boundsSizeUniform				= glGetUniformLocation(_shaderProgram, "boundsSize");
	_boundsOriginUniform			= glGetUniformLocation(_shaderProgram, "boundsOrigin");

	GLint texIDUniform				= glGetUniformLocation(_shaderProgram, "texID");
	GLint shadowMaskTexIDUniform	= glGetUniformLocation(_shaderProgram, "shadowMaskTexID");

	[self pushSizeUniforms];

	glUniform1i(texIDUniform, 0);
	glUniform1i(shadowMaskTexIDUniform, 1);

	glEnableVertexAttribArray((GLuint)_positionAttribute);
	glEnableVertexAttribArray((GLuint)_textureCoordinatesAttribute);
	glEnableVertexAttribArray((GLuint)_lateralAttribute);

	const GLsizei vertexStride = kCRTSizeOfVertex;
	glVertexAttribPointer((GLuint)_positionAttribute,			2, GL_UNSIGNED_SHORT,	GL_TRUE,	vertexStride, (void *)kCRTVertexOffsetOfPosition);
	glVertexAttribPointer((GLuint)_textureCoordinatesAttribute, 2, GL_UNSIGNED_SHORT,	GL_FALSE,	vertexStride, (void *)kCRTVertexOffsetOfTexCoord);
	glVertexAttribPointer((GLuint)_lateralAttribute,			1, GL_UNSIGNED_BYTE,	GL_FALSE,	vertexStride, (void *)kCRTVertexOffsetOfLateral);

	glGenTextures(1, &_textureName);
	glBindTexture(GL_TEXTURE_2D, _textureName);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
}

- (void)drawRect:(NSRect)dirtyRect
{
	[self drawView];
}

- (void)drawView
{
	[self.openGLContext makeCurrentContext];
	CGLLockContext([[self openGLContext] CGLContextObj]);

	while((!_shaderProgram || (_signalDecoderGeneration != _compiledSignalDecoderGeneration)) && _signalDecoder) {
		_compiledSignalDecoderGeneration = _signalDecoderGeneration;
		[self prepareShader];
	}

	glClear(GL_COLOR_BUFFER_BIT);

	if (_crtFrame)
	{
		if(_textureSizeUniform >= 0) glUniform2f(_textureSizeUniform, _crtFrame->size.width, _crtFrame->size.height);
		glDrawArrays(GL_TRIANGLES, 0, (GLsizei)(_crtFrame->number_of_runs*6));
	}

	CGLFlushDrawable([[self openGLContext] CGLContextObj]);
	CGLUnlockContext([[self openGLContext] CGLContextObj]);
}

#pragma mark - NSResponder

- (BOOL)acceptsFirstResponder
{
	return YES;
}

- (void)keyDown:(NSEvent *)theEvent
{
	[self.responderDelegate keyDown:theEvent];
}

- (void)keyUp:(NSEvent *)theEvent
{
	[self.responderDelegate keyUp:theEvent];
}

- (void)flagsChanged:(NSEvent *)theEvent
{
	[self.responderDelegate flagsChanged:theEvent];
}

@end