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

#include <raylib.h>
#include <raymath.h>

#define PIPE_COUNT 10
#define PIPE_INTERVAL 300
#define PIPE_WIDTH 100
#define PIPE_GAP 150

#define BIRD_ANIMATION_FRAME_COUNT 4
#define BIRD_ANIMATION_FRAME_TIME 0.1
#define PATH "./"

struct game_state {
	Vector2 bird_position;
	Vector2 bird_velocity;
	Texture2D texture;
	Rectangle bird_texture[BIRD_ANIMATION_FRAME_COUNT];
	struct animation {
		int frame;
		double clock;
	} bird_animation;
	NPatchInfo pipe_texture_top;
	NPatchInfo pipe_texture_bottom;
	struct pipe {
		Vector2 position;
	} pipe[PIPE_COUNT];
	struct death_state {
		double angle;
		Vector2 velocity;
	} death;
	struct background_state {
		Texture2D dune;
		Texture2D cloud[2];
		double scroll;
	} background;
};

void init_game_state(struct game_state *state);

Rectangle dune_destination_to_source(int texture_width, int texture_height, Rectangle destination) {
	float q = 100 / destination.height;
	return (Rectangle) {
		0, q
		,texture_height * destination.width / destination.height
		,texture_height - q * 2
	};
}

void draw_background(struct background_state *state) {
	int window_width = GetRenderWidth();
	int window_height = GetRenderHeight();
	ClearBackground((Color) { 135, 206, 235, 0 });
	double y = window_height / 2;
	double height = window_height * 0.05;
	int offset = 1;
	DrawRectangle(0, window_height / 2, window_width, window_height / 2, (Color) { 243, 202, 35, 255 });
	double scroll_speed = 0.2;
	for (int i = 0; i < 5; i++) {
		Rectangle destination = (Rectangle) { 0, y, window_width, height };
		Rectangle source = dune_destination_to_source(state->dune.width, state->dune.height, destination);
		source.x = state->scroll * scroll_speed + offset;
		scroll_speed *= 2.0;
		offset = offset * 37 % 240;
		DrawTexturePro(state->dune
			,source
			,destination
			,(Vector2) { 0, height }
			,0
			,WHITE
		);
		y += height * 0.8577;
		height *= 1.8;
	}
	double texture_width[3] = { 392, 392, 500 };
	Texture2D texture[3] = { state->cloud[1], state->cloud[1], state->cloud[0] };
	double texture_height[3] = { 280, 220, 265 };
	double texture_y[3] = { 0, 280, 0 };
	height = window_height / 10;
	y = window_height * 0.4;
	scroll_speed = 0.1;
	for (int j = 0; j < 8; j++) {
		int i = j % 3;
		Rectangle destination = (Rectangle) { 0, y, window_width, height };
		Rectangle source = dune_destination_to_source(texture_width[i], texture_height[i], destination);
		source.y = texture_y[i];
		source.x = state->scroll * scroll_speed + offset;
		offset = offset * 37 % 240;
		scroll_speed *= 1.2;
		DrawTexturePro(texture[i]
			,source
			,destination
			,(Vector2) { 0, height }
			,0
			,WHITE
		);
		y -= height * 0.083;
		height *= 1.3;

	}
}

void animation_update(struct animation *animation, double dt, double frame_time, int frame_count) {
	animation->clock += dt;
	if (animation->clock > frame_time) {
		animation->frame = (animation->frame + 1) % frame_count;
		animation->clock = 0;
	}
}

double clamp(double x, double a, double b) {
	return x < a ? a : x > b ? b : x;
}

double rect_distance(Rectangle r, Vector2 p) {
	Vector2 dim = (Vector2) { r.width * 0.5, r.height * 0.5 };
	p = (Vector2) { abs(p.x - r.x - r.width / 2), abs(p.y - r.y - r.height / 2) };
	Vector2 d = Vector2Subtract(p, dim); 
	d = (Vector2) { d.x < 0 ? 0 : d.x, d.y < 0 ? 0 : d.y };
	return Vector2Length(d);
}

double pipe_height(double window_height, double pipe_buffer) {
	return rand() / (RAND_MAX / (window_height - pipe_buffer * 2)) + pipe_buffer;
}

Rectangle pipe_top(struct pipe pipe, double width, double gap, double window_height) {
	return (Rectangle) {
		pipe.position.x - width / 2, 0
		,width, pipe.position.y - gap / 2
	};
}

Rectangle pipe_bottom(struct pipe pipe, double width, double gap, double window_height) {
	return (Rectangle) {
		pipe.position.x - width / 2, pipe.position.y + gap / 2
		,width, window_height - pipe.position.y - gap / 2
	};
}

double pipe_last(struct pipe *pipe, int count) {
	if (count < 1) {
		return 0;
	}
	double last = pipe[0].position.x;
	for (int i = 1; i < count; i++) {
		last = pipe[i].position.x > last ? pipe[i].position.x : last;
	}
	return last;
}

double pipe_distance(struct pipe *pipe, int count, double width, double gap, double window_height, Vector2 p) {
	double d = INFINITY;
	for (int i = 0; i < count; i++) {
		double top_distance = rect_distance(pipe_top(pipe[i], width, gap, window_height), p)
			,bottom_distance = rect_distance(pipe_bottom(pipe[i], width, gap, window_height), p);
		d = top_distance < d ? top_distance : d;
		d = bottom_distance < d ? bottom_distance : d;
	}
	return d;
}

enum game_screen {
	PLAY_SCREEN
	,TAP_SPACE_SCREEN
	,DEATH_SCREEN
	,TEST_SCREEN
};

#define BIRD_WIDTH 80
#define BIRD_HEIGHT (BIRD_WIDTH * 0.6)
#define HIT_RADIUS (BIRD_HEIGHT * 0.4)

void draw_game(struct game_state *state) {
	int window_width = GetRenderWidth();
	int window_height = GetRenderHeight();
	float angle = atan(state->bird_velocity.y / state->bird_velocity.x) * 180 / M_PI;
	if (state->bird_velocity.x < 0) {
		angle += 180;
	}
	draw_background(&state->background);
	DrawTexturePro(
		state->texture
		,state->bird_texture[state->bird_animation.frame]
		,(Rectangle) {
			state->bird_position.x, state->bird_position.y
			,BIRD_WIDTH, BIRD_HEIGHT
		}
		,(Vector2) { BIRD_WIDTH / 2, BIRD_HEIGHT / 2 }
		,angle
		,WHITE
	);
	//DrawCircleLinesV(state->bird_position, HIT_RADIUS, PURPLE);
	for (int i = 0; i < PIPE_COUNT; i++) {
		DrawTextureNPatch(
			state->texture
			,state->pipe_texture_top
			,pipe_top(state->pipe[i], PIPE_WIDTH, PIPE_GAP, window_height)
			,(Vector2) { 0, 0 }
			,0
			,WHITE
		);
		DrawTextureNPatch(
			state->texture
			,state->pipe_texture_bottom
			,pipe_bottom(state->pipe[i], PIPE_WIDTH, PIPE_GAP, window_height)
			,(Vector2) { 0, 0 }
			,0
			,WHITE
		);
	}
	return;
}

enum game_screen play_game(struct game_state *state) {
	int window_width = GetRenderWidth();
	int window_height = GetRenderHeight();
	BeginDrawing();
		ClearBackground(BLACK);
		draw_game(state);
	EndDrawing();
	if (pipe_distance(state->pipe, PIPE_COUNT, PIPE_WIDTH, PIPE_GAP, window_height, state->bird_position) < HIT_RADIUS
		|| state->bird_position.y >= window_height - BIRD_HEIGHT / 2 - 1
	) {
		state->death.angle = atan(state->bird_velocity.y / state->bird_velocity.x);
		state->death.velocity = (Vector2) { state->bird_velocity.x, -state->bird_velocity.x };
		return DEATH_SCREEN;
	}
	double dt = GetFrameTime();
	state->bird_position.y += state->bird_velocity.y * dt * 10;
	state->bird_velocity.y += 100 * dt;
	state->bird_position.y = clamp(state->bird_position.y, BIRD_HEIGHT / 2, window_height - BIRD_HEIGHT / 2);
	state->bird_velocity.y = clamp(state->bird_velocity.y, -100, 100);
	if (IsKeyPressed(KEY_SPACE)) {
		state->bird_velocity.y = -40;
	}
	for (int i = 0; i < PIPE_COUNT; i++) {
		state->pipe[i].position.x -= state->bird_velocity.x * dt * 2;
		if (state->pipe[i].position.x < -PIPE_WIDTH) {
			state->pipe[i].position.x = pipe_last(state->pipe, PIPE_COUNT) + PIPE_INTERVAL;
			state->pipe[i].position.y = pipe_height(window_height, 100);
		}
	}
	state->background.scroll += state->bird_velocity.x * dt * 0.4;
	animation_update(&state->bird_animation, dt, BIRD_ANIMATION_FRAME_TIME, BIRD_ANIMATION_FRAME_COUNT);
	return PLAY_SCREEN;
}

enum game_screen tap_space_screen(struct game_state *state) {
	state->bird_velocity.y = 0;
	int window_width = GetRenderWidth();
	int window_height = GetRenderHeight();
	BeginDrawing();
	{
		draw_game(state);
		char *text = "SPACE";
		int text_height = window_width / 20;
		int text_width = MeasureText(text, text_height);
		DrawText(text, (window_width - text_width) / 2, window_height * 2 / 3, text_height, WHITE);
	}
	EndDrawing();
	double dt = GetFrameTime();
	state->background.scroll += state->bird_velocity.x * dt * 0.4;
	if (IsKeyPressed(KEY_SPACE)) {
		state->bird_velocity.y = -40;
		return PLAY_SCREEN;
	}
	animation_update(&state->bird_animation, dt, BIRD_ANIMATION_FRAME_TIME, BIRD_ANIMATION_FRAME_COUNT);
	return TAP_SPACE_SCREEN;
}

enum game_screen death_screen(struct game_state *state) {
	int window_width = GetRenderWidth()
		,window_height = GetRenderHeight();
	BeginDrawing();
	{
		ClearBackground((Color) { 135, 206, 235, 0 });
		draw_game(state);
		double fade = clamp((state->bird_position.y - window_height) / window_height, 0, 1);
		DrawRectangle(0, 0, window_width, window_height, (Color) { 0, 0, 0, (fade) * 255 });
		int text_height = window_height / 4;
		char *text = "YOU DIED";
		int text_width = MeasureText(text, text_height);
		DrawText(text, window_width / 2 - text_width / 2, window_height / 2 - text_height / 2, text_height, (Color) { 255, 0, 0, clamp((fade - 0.5) * 2, 0, 1) * 255 });
	}
	EndDrawing();
	double dt = GetFrameTime();
	state->death.angle += dt * 20;
	state->bird_velocity = (Vector2) { cos(state->death.angle), sin(state->death.angle) };
	state->bird_position = Vector2Add(state->bird_position, Vector2Scale(state->death.velocity, dt * 8));
	state->death.velocity.y += 200 * dt;
	if (state->bird_position.y > window_height * 10) {
		init_game_state(state);
		return TAP_SPACE_SCREEN;
	}
	return DEATH_SCREEN;
}

enum game_screen test_screen(struct game_state *state) {
	BeginDrawing();
		draw_background(&state->background);
	EndDrawing();
	double dt = GetFrameTime();
	state->background.scroll += dt * 100;
	return TEST_SCREEN;
}

void init_game_state(struct game_state *state) {
	int window_width = GetRenderWidth();
	int window_height = GetRenderHeight();
	state->bird_position = (Vector2) { window_width / 2, window_height / 2 };
	state->bird_velocity = (Vector2) { 40, -40 };
	state->background.scroll = 0;
	for (int i = 0; i < PIPE_COUNT; i++) {
		state->pipe[i].position = (Vector2) {
			i * PIPE_INTERVAL + window_width + PIPE_WIDTH
			,pipe_height(window_height, PIPE_GAP * 0.5)
		};
	}
}

int main(int argc, char **argv) {
	const int window_width = 800;
	const int window_height = 450;

	InitWindow(window_width, window_height, "flappybird");

	SetTargetFPS(60);
	struct game_state state;
	state.texture = LoadTexture(PATH "bird2.png");
	GenTextureMipmaps(&state.texture);
	SetTextureFilter(state.texture, TEXTURE_FILTER_BILINEAR);
	for (int i = 0; i < BIRD_ANIMATION_FRAME_COUNT; i++) {
		state.bird_texture[i] = (Rectangle) { 2, 128 * (i == 3 ? 1 : i) + 9, -196, 110 };
	}
	state.bird_animation.frame = 0;
	state.bird_animation.clock = 0;
	state.pipe_texture_bottom = (NPatchInfo) {
		(Rectangle) { 202, 2, 104, 124 }
		,0, 47, 0, 0
		,NPATCH_NINE_PATCH
	};
	state.pipe_texture_top = (NPatchInfo) {
		(Rectangle) { 315, 0, 104, 124 }
		,0, 0, 0, 47
		,NPATCH_NINE_PATCH
	};
	srand(666);
	state.background.dune = LoadTexture(PATH "dune.png");
	state.background.cloud[0] = LoadTexture(PATH "cloud_1.png");
	state.background.cloud[1] = LoadTexture(PATH "cloud_2.png");
	
	GenTextureMipmaps(&state.background.dune);
	GenTextureMipmaps(&state.background.cloud[0]);
	GenTextureMipmaps(&state.background.cloud[1]);
	SetTextureFilter(state.background.dune, TEXTURE_FILTER_BILINEAR);
	SetTextureWrap(state.background.dune, TEXTURE_WRAP_REPEAT);
	SetTextureFilter(state.background.cloud[0], TEXTURE_FILTER_BILINEAR);
	SetTextureFilter(state.background.cloud[1], TEXTURE_FILTER_BILINEAR);
	init_game_state(&state);

	enum game_screen screen = TAP_SPACE_SCREEN;
	while (!WindowShouldClose()) {
		switch (screen) {
		case PLAY_SCREEN:
			screen = play_game(&state);
			break;
		case DEATH_SCREEN:
			screen = death_screen(&state);
			break;
		case TEST_SCREEN:
			screen = test_screen(&state);
			break;
		case TAP_SPACE_SCREEN:
			screen = tap_space_screen(&state);
			break;
		default:
			BeginDrawing();
				ClearBackground(RED);
			EndDrawing();
			break;
		}

	}
	CloseWindow();
	UnloadTexture(state.texture);
	UnloadTexture(state.background.dune);
	UnloadTexture(state.background.cloud[0]);
	UnloadTexture(state.background.cloud[1]);
	return 0;
}