/*
  Copyright (c) 2018 Alex Diener
  
  This software is provided 'as-is', without any express or implied
  warranty. In no event will the authors be held liable for any damages
  arising from the use of this software.
  
  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:
  
  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
  
  Alex Diener alex@ludobloom.com
*/

#include "renderer/Renderer.h"
#include "renderer/GLIncludes.h"
#include "renderer/VertexTypes.h"
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef STEM_PLATFORM_android
#include <android/log.h>
#define printf(format, ...) __android_log_print(ANDROID_LOG_INFO, "Renderer", format, ##__VA_ARGS__);
#define fprintf(stderr, format, ...) __android_log_print(ANDROID_LOG_INFO, "Renderer", format, ##__VA_ARGS__);
#endif

#define stemobject_implementation Renderer
stemobject_vtable_begin();
stemobject_vtable_entry(dispose);
stemobject_vtable_end();

Renderer * Renderer_create(void) {
	stemobject_create_implementation(init)
}

bool Renderer_init(Renderer * self) {
	call_super(init, self);
	initGLFunctionPointers();
	
	GLint viewport[4];
	glGetIntegerv(GL_VIEWPORT, viewport);
	self->viewportX = viewport[0];
	self->viewportY = viewport[1];
	self->viewportWidth = viewport[2];
	self->viewportHeight = viewport[3];
	self->activeRenderTarget = NULL;
	self->currentPipelineState = default2DRenderPipelineConfiguration(RENDER_BLEND_NONE);
	applyRenderPipelineConfiguration(&self->currentPipelineState);
	glBlendEquationSeparate(GL_FUNC_ADD, GL_MAX);
	
	self->vertexBufferCount = 0;
	self->vertexBuffers = NULL;
	
	return true;
}

void Renderer_dispose(Renderer * self) {
	for (unsigned int bufferIndex = 0; bufferIndex < self->vertexBufferCount; bufferIndex++) {
		VertexBuffer_dispose(self->vertexBuffers[bufferIndex].buffer);
	}
	free(self->vertexBuffers);
	call_super(dispose, self);
}

void Renderer_clear(Renderer * self, Color4f color) {
	glClearColor(color.red, color.green, color.blue, color.alpha);
	glDepthMask(GL_TRUE);
	self->currentPipelineState.depthWriteEnabled = true;
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

void Renderer_clearDepth(Renderer * self) {
	glDepthMask(GL_TRUE);
	self->currentPipelineState.depthWriteEnabled = true;
	glClear(GL_DEPTH_BUFFER_BIT);
}

void Renderer_setRenderTarget(Renderer * self, RenderTarget * renderTarget) {
	if (renderTarget == NULL) {
		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
		glViewport(self->viewportX, self->viewportY, self->viewportWidth, self->viewportHeight);
	} else {
		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, renderTarget->fboID);
		glViewport(renderTarget->viewportX, renderTarget->viewportY, renderTarget->viewportWidth, renderTarget->viewportHeight);
	}
	self->activeRenderTarget = renderTarget;
}

void Renderer_setViewport(Renderer * self, int x, int y, unsigned int width, unsigned int height, RenderTarget * renderTarget) {
	if (renderTarget == NULL) {
		self->viewportX = x;
		self->viewportY = y;
		self->viewportWidth = width;
		self->viewportHeight = height;
	} else {
		RenderTarget_setViewport(renderTarget, x, y, width, height);
	}
	if (self->activeRenderTarget == renderTarget) {
		glViewport(x, y, width, height);
	}
}

static Rect4i getActiveViewport(Renderer * self) {
	if (self->activeRenderTarget == NULL) {
		return RECT4i(self->viewportX, self->viewportX + self->viewportWidth, self->viewportY, self->viewportY + self->viewportHeight);
	}
	return RECT4i(self->activeRenderTarget->viewportX, self->activeRenderTarget->viewportX + self->activeRenderTarget->viewportWidth, self->activeRenderTarget->viewportY, self->activeRenderTarget->viewportY + self->activeRenderTarget->viewportHeight);
}

static VertexBuffer * vertexBufferForFormat(Renderer * self, VertexFormat * vertexFormat) {
	for (unsigned int bufferIndex = 0; bufferIndex < self->vertexBufferCount; bufferIndex++) {
		if (self->vertexBuffers[bufferIndex].format == vertexFormat) {
			return self->vertexBuffers[bufferIndex].buffer;
		}
	}
	self->vertexBuffers = realloc(self->vertexBuffers, (self->vertexBufferCount + 1) * sizeof(*self->vertexBuffers));
	self->vertexBuffers[self->vertexBufferCount].format = vertexFormat;
	self->vertexBuffers[self->vertexBufferCount].buffer = VertexBuffer_create(vertexFormat, NULL, 0, NULL, 0, BUFFER_USAGE_STREAM);
	return self->vertexBuffers[self->vertexBufferCount++].buffer;
}

static void applyScissor(Rect4i clipBounds, Rect4i viewport) {
	if (Rect4i_isEmpty(clipBounds)) {
		glDisable(GL_SCISSOR_TEST);
	} else {
		glEnable(GL_SCISSOR_TEST);
		glScissor(clipBounds.xMin + viewport.xMin, clipBounds.yMin + viewport.yMin, clipBounds.xMax - clipBounds.xMin, clipBounds.yMax - clipBounds.yMin);
	}
}

#define drawBufferedVertices() \
	glBindVertexArray(vertexBuffer->vaoID); \
	VertexBuffer_bufferData(vertexBuffer, vertexIO->vertices, vertexIO->vertexCount, vertexIO->indexes, vertexIO->indexCount, BUFFER_USAGE_STREAM); \
	applyRenderPipelineConfigurationDelta(lastRenderable->pipelineConfiguration, &self->currentPipelineState); \
	applyScissor(lastClipBounds, viewport); \
	call_virtual(apply, lastRenderable->shaderConfiguration); \
	glDrawElements(lastRenderable->primitiveType, vertexIO->indexCount, GL_UNSIGNED_INT, 0); \
	VertexIO_dispose(vertexIO);

void Renderer_drawLayer(Renderer * self, RenderLayer * layer, double referenceTime, double deltaTime) {
	RenderLayer_prepareRenderables(layer);
	unsigned int renderableCount = layer->renderableIO->renderableCount;
	if (renderableCount == 0) {
		return;
	}
	
	struct RenderableIO_renderableEntry * renderables = layer->renderableIO->renderables;
	Renderable * lastRenderable = NULL;
	VertexBuffer * vertexBuffer = NULL;
	VertexIO * vertexIO = NULL;
	Rect4i lastClipBounds = RECT4i_EMPTY;
	Rect4i viewport = getActiveViewport(self);
	for (unsigned int renderableIndex = 0; renderableIndex < renderableCount; renderableIndex++) {
		Renderable * renderable = renderables[renderableIndex].renderable;
		Rect4i clipBounds = renderables[renderableIndex].clipBounds;
		if (!renderable->visible) {
			continue;
		}
		
		if (renderable->vertexBuffer != NULL) {
			if (vertexBuffer != NULL) {
				drawBufferedVertices();
				vertexBuffer = NULL;
			}
			glBindVertexArray(renderable->vertexBuffer->vaoID);
			if (renderable->prepareCallback != NULL) {
				renderable->prepareCallback(renderable, referenceTime, deltaTime, renderable->callbackContext);
			}
			applyRenderPipelineConfigurationDelta(renderable->pipelineConfiguration, &self->currentPipelineState);
			applyScissor(clipBounds, viewport);
			call_virtual(apply, renderable->shaderConfiguration);
			glDrawElements(renderable->primitiveType, renderable->vertexBuffer->indexCount, GL_UNSIGNED_INT, 0);
			
		} else {
			if (renderable->prepareCallback != NULL) {
				renderable->prepareCallback(renderable, referenceTime, deltaTime, renderable->callbackContext);
			}
			if (vertexBuffer != NULL &&
			    (renderable->primitiveType != lastRenderable->primitiveType ||
			     call_virtual(compare, renderable->shaderConfiguration, lastRenderable->shaderConfiguration) ||
			     compareRenderPipelineConfiguration(renderable->pipelineConfiguration, lastRenderable->pipelineConfiguration) ||
			     !Rect4i_isEqual(clipBounds, lastClipBounds))) {
				drawBufferedVertices();
				vertexBuffer = NULL;
			}
			if (vertexBuffer == NULL) {
				vertexBuffer = vertexBufferForFormat(self, renderable->shaderConfiguration->shader->vertexFormat);
				vertexIO = VertexIO_create(vertexBuffer->vertexFormat, referenceTime, deltaTime);
				for (unsigned int textureIndex = 0; textureIndex < VERTEXIO_TEXTURE_COUNT_MAX; textureIndex++) {
					vertexIO->textureBinds[textureIndex] = Texture_getTextureID(ShaderConfiguration_getTexture(renderable->shaderConfiguration, textureIndex));
				}
			}
			renderable->writeVerticesCallback(renderable, vertexIO, renderable->callbackContext);
		}
		lastRenderable = renderable;
		lastClipBounds = clipBounds;
	}
	if (vertexBuffer != NULL) {
		drawBufferedVertices();
	}
	glBindVertexArray(0);
	glDisable(GL_SCISSOR_TEST);
}

void Renderer_drawVertexBuffer(Renderer * self, RenderPipelineConfiguration * pipelineConfiguration, PrimitiveType primitiveType, compat_type(ShaderConfiguration *) shaderConfigurationUntyped, Rect4i clipBounds, VertexBuffer * vertexBuffer) {
	ShaderConfiguration * shaderConfiguration = shaderConfigurationUntyped;
	applyRenderPipelineConfigurationDelta(pipelineConfiguration, &self->currentPipelineState);
	applyScissor(clipBounds, getActiveViewport(self));
	call_virtual(apply, shaderConfiguration);
	glBindVertexArray(vertexBuffer->vaoID);
	glDrawElements(primitiveType, vertexBuffer->indexCount, GL_UNSIGNED_INT, 0);
	glDisable(GL_SCISSOR_TEST);
}