#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>

inline int
OK(int x) {
	return x == 0;
}

typedef uint8_t bool;
#define false 0
#define true 1

typedef uint32_t u32;

////RGBImage////

typedef uint8_t  byte;
typedef uint16_t byte2;
typedef uint32_t byte4;

typedef struct ARGB {
	byte a;
	byte r;
	byte g;
	byte b;
} ARGB;

void
ARGB_set(ARGB* rgb, byte4 color) {
	rgb->a = (0xFF000000 & color) >> 24;
	rgb->r = (0x00FF0000 & color) >> 16;
	rgb->g = (0x0000FF00 & color) >> 8;
	rgb->b = (0x000000FF & color);
}

void
ARGB_merge(ARGB* bottom, ARGB top) {
	bottom->a = 255;
	double perc = top.a / 255.0;

	bottom->r = (bottom->r * (1.0 - perc)) + (top.r * perc);
	bottom->g = (bottom->g * (1.0 - perc)) + (top.g * perc);
	bottom->b = (bottom->b * (1.0 - perc)) + (top.b * perc);
}

typedef struct RGBImage {
	u32 width;
	u32 height;
	ARGB* img;
} RGBImage;

RGBImage
RGBImage_new(u32 width, u32 height) {
	return (RGBImage){
		.width  = width,
		.height = height,
		.img    = malloc(sizeof(ARGB) * width * height)
	};
}

void
RGBImage_free(RGBImage img) {
	free(img.img);
}

void
RGBImage_delete(RGBImage* img) {
	RGBImage_free(*img);
	img->width = img->height = 0;
	img->img = NULL;
}

ARGB*
RGBImage_at(RGBImage img, int row, int col) {
	return img.img + (row % img.height) * img.width + col % img.width;
}

int
ppm6_write(FILE* f, RGBImage img) {
	fprintf(f, "P6\n%d %d\n255\n", img.width, img.height);
	size_t size = img.width * img.height;
	for (size_t i = 0; i < size; ++i) {
		fputc(img.img[i].r, f);
		fputc(img.img[i].g, f);
		fputc(img.img[i].b, f);
	}
	return fflush(f);
}

////Animation////

struct AnimationEventNode;
typedef struct AnimationEventNode AnimationEventNode;

typedef struct Animation {
	u32 width;
	u32 height;
	u32 frameCount;

	RGBImage frameBuffer;
	AnimationEventNode* events;
} Animation;

typedef ARGB (*PixelRenderer)(const Animation* anim, u32 currentFrame, const ARGB* pixel, u32 row, u32 col, void* priv);

struct AnimationEventNode {
	AnimationEventNode* next;

	u32 startFrame;
	u32 endFrame;
	PixelRenderer renderCallback;
	void* privateData;
};

AnimationEventNode*
AnimationEventNode_new(u32 startFrame, u32 endFrame, PixelRenderer renderCallback, void* privateData) {
	AnimationEventNode* aen = (AnimationEventNode*)malloc(sizeof(AnimationEventNode));
	aen->next = NULL;
	aen->startFrame = startFrame;
	aen->endFrame = endFrame;
	aen->renderCallback = renderCallback;
	aen->privateData = privateData;

	return aen;
}

Animation
Animation_new(u32 width, u32 height, u32 frameCount) {
	return (Animation){
		.width       = width,
		.height      = height,
		.frameCount  = frameCount,
		.frameBuffer = RGBImage_new(width, height),
		.events      = NULL,
	};
}

void
Animation_free(Animation anim) {
	RGBImage_free(anim.frameBuffer);
	while (anim.events != NULL) {
		AnimationEventNode* toFree = anim.events;
		anim.events = anim.events->next;
		free(toFree);
	}
}

void
Animation_delete(Animation* anim) {
	Animation_free(*anim);
	anim->width = anim->height = anim->frameCount = 0;
	RGBImage_delete(&anim->frameBuffer);
}

void
Animation_pushEvent(Animation* anim, u32 startFrame, u32 endFrame, PixelRenderer renderer, void* privateData) {
	if (anim->events == NULL) {
		anim->events = AnimationEventNode_new(startFrame, endFrame, renderer, privateData);
		return;
	}

	AnimationEventNode* prevNode = NULL, *currNode = anim->events;
	while (currNode != NULL) {
		if (startFrame < currNode->startFrame) {
			prevNode->next = AnimationEventNode_new(startFrame, endFrame, renderer, privateData);
			prevNode->next->next = currNode;
			return;
		}

		prevNode = currNode;
		currNode = currNode->next;
	}

	prevNode->next = AnimationEventNode_new(startFrame, endFrame, renderer, privateData);
}

void
Animation_render(Animation* anim) {
	for (int currFrame = 0; currFrame < anim->frameCount; ++currFrame) {

		if (anim->events != NULL)
			for (int r = 0; r < anim->frameBuffer.width; ++r)
			for (int c = 0; c < anim->frameBuffer.height; ++c) {
				for (AnimationEventNode* aen = anim->events; aen != NULL && aen->startFrame <= currFrame; aen = aen->next) {
					ARGB* pixel = RGBImage_at(anim->frameBuffer, r, c);
					ARGB newPixel = aen->renderCallback(anim, currFrame, pixel, r, c, aen->privateData);
					ARGB_merge(pixel, newPixel);
				}

				AnimationEventNode* prevNode = NULL, *currNode = anim->events;
				while (currNode != NULL && currNode->startFrame <= currFrame) {
					if (currNode->endFrame <= currFrame) {
						if (prevNode != NULL)
							prevNode->next = currNode->next;
						else
							anim->events = NULL;
						free(currNode);
					}
					else {
						prevNode = currNode;
						currNode = currNode->next;
					}
				}
			}

		ppm6_write(stdout, anim->frameBuffer);
	}
}

////main////

ARGB
MovingBackground(const Animation* anim, u32 frameIndex, const ARGB* currentPixel, u32 r, u32 c, void* priv) {
	ARGB pixel;

	r = (r + frameIndex) / 32;
	c = (c + frameIndex) / 32;

	if ((r + c) % 2 == 0) {
		ARGB_set(&pixel, 0xFF000000);
	}
	else {
		ARGB_set(&pixel, 0xFFFF00FF);
	}

	return pixel;
}

struct SquareSettings {
	u32 width;
	u32 height;
	byte4 color;
};

ARGB
Square(const Animation* anim, u32 frameIndex, const ARGB* currentPixel, u32 r, u32 c, void* priv) {
	ARGB pixel;
	memcpy(&pixel, currentPixel, sizeof(ARGB));

	struct SquareSettings* set = (struct SquareSettings*)priv;

	r = (r - frameIndex * 8) % anim->width;
	c = (c - frameIndex * 8) % anim->height;

	if (0 <= r && r <= set->width && 0 <= c && c <= set->height) {
		ARGB_set(&pixel, set->color);
	}

	return pixel;
}

int
main() {
	Animation anim = Animation_new(512, 512, 120);

	Animation_pushEvent(&anim, 0, 120, MovingBackground, NULL);

	struct SquareSettings s1 = {
		.width = 20, .height = 20, .color = 0xFFFFFF00,
	};
	Animation_pushEvent(&anim, 0, 30, Square, &s1);

	struct SquareSettings s2 = {
		.width = 10, .height = 25, .color = 0x5009FAA5,
	};
	Animation_pushEvent(&anim, 60, 100, Square, &s2);

	Animation_render(&anim);

	Animation_delete(&anim);

	return 0;
}