/*
 * corridor: a small first person level, walls from a tilemap, sprites that face you, and collision on the same map
 *
 * build:  ./build.sh -d -m tile,font obj/corridor
 *         ./build.sh -d -m tile,font,assets,image obj/corridor   (also loads sprites/marker.png from the assets if there is one)
 * run:    obj/corridor
 *
 * click to grab the mouse and look around with it, tab lets go. with the debug module the variable sens sets the mouse speed. w and s walk, a and d strafe, the arrows turn too
 * the walls are quads made from the tilemap every frame, the markers are billboards drawn with depth so walls hide them
 * the markers are plain placeholders, put your own sprite in assets/sprites/marker.png to see it in their place
 */

#include <stdio.h>
#include <math.h>

#include "konprogram.h"
#include "kontile.h"

#if !defined(KON_MODULE_TILE) || !defined(KON_MODULE_FONT)
#error "build with: ./build.sh -d -m tile,font obj/corridor"
#endif

#define COLUMNS 16
#define ROWS 16
#define TILE 32 /* map pixels in one world unit, the collision works in those */
#define WALL_HEIGHT 1.2f
#define MARKERS 5

#define COL_SKY 0xFF1B1826u
#define COL_DIM 0xFF9A93B3u

static const char *level[ROWS] = {
	"################",
	"#..............#",
	"#.####....####.#",
	"#.#..........#.#",
	"#.#..........#.#",
	"#.#...####...#.#",
	"#.....#..#.....#",
	"#.....#..#.....#",
	"#.#...#..#...#.#",
	"#.#...####...#.#",
	"#.#..........#.#",
	"#.#..........#.#",
	"#.####....####.#",
	"#..............#",
	"#..............#",
	"################",
};

typedef struct state {
	kon_tilemap_t map;
	uint16_t tiles[COLUMNS * ROWS];
	uint8_t solid[2];

	kon_image *brick, *floor, *marker;
	int ownsMarker;
	kon_box2_t player; /* map pixels */
	float yaw, pitch;
	float sensitivity; /* radians per pixel */
	int forward, strafe, turn;
	double time;
	kon_vec2_t markers[MARKERS]; /* world units */
} state_t;

/*** images made in code ***/

static kon_image *makeBrick(void)
{
	kon_image *image = kon_createFramebuffer(32, 32);
	int row, i;

	if (!image) return NULL;
	kon_clearFramebuffer(image, 0xFF6B5F92);
	for (row = 0; row < 4; row++) {
		kon_fillRectangle(image, 0, row * 8, 32, 1, 0xFF3A3558);
		for (i = 0; i < 2; i++) kon_fillRectangle(image, (row % 2) * 8 + i * 16, row * 8, 1, 8, 0xFF3A3558);
	}
	return image;
}

static kon_image *makeFloor(void)
{
	kon_image *image = kon_createFramebuffer(32, 32);

	if (!image) return NULL;
	kon_clearFramebuffer(image, 0xFF2A2640);
	kon_fillRectangle(image, 0, 0, 16, 16, 0xFF332E4E);
	kon_fillRectangle(image, 16, 16, 16, 16, 0xFF332E4E);
	return image;
}

static kon_image *makeMarker(void)
{
	kon_image *image = kon_createFramebuffer(32, 40);
	int i;

	if (!image) return NULL;
	kon_clearFramebuffer(image, 0xFF6B5F92);
	kon_fillRectangle(image, 2, 2, 28, 36, 0xFF332E4E);
	for (i = 0; i < 28; i++) {
		kon_fillRectangle(image, 2 + i, 2 + i * 36 / 28, 1, 1, 0xFF6B5F92);
		kon_fillRectangle(image, 2 + i, 37 - i * 36 / 28, 1, 1, 0xFF6B5F92);
	}
	return image;
}

/*** drawing ***/

static void quad(kon_framebuffer_t *fb, kon_mat4_t vp, const kon_material_t *material, const kon_light_t *light,
		kon_vec3_t a, kon_vec3_t b, kon_vec3_t c, kon_vec3_t d, kon_vec3_t normal, kon_vec2_t uvA, kon_vec2_t uvC)
{
	kon_vertex_t va = { a, normal, uvA }, vb = { b, normal, KON_VEC2(uvC.x, uvA.y) };
	kon_vertex_t vc = { c, normal, uvC }, vd = { d, normal, KON_VEC2(uvA.x, uvC.y) };

	kon_drawTriangle3D(fb, vp, va, vb, vc, material, light, KON_RENDER_DEFAULT);
	kon_drawTriangle3D(fb, vp, va, vc, vd, material, light, KON_RENDER_DEFAULT);
}

/* a wall face seen from its open side: bottom left and bottom right are as the viewer sees them */
static void wall(kon_framebuffer_t *fb, kon_mat4_t vp, const kon_material_t *material, const kon_light_t *light,
		kon_vec3_t left, kon_vec3_t right, kon_vec3_t normal)
{
	kon_vec3_t topRight = KON_VEC3(right.x, WALL_HEIGHT, right.z), topLeft = KON_VEC3(left.x, WALL_HEIGHT, left.z);

	quad(fb, vp, material, light, left, right, topRight, topLeft, normal, KON_VEC2(0, WALL_HEIGHT), KON_VEC2(1, 0));
}

static int open(const state_t *state, int column, int row)
{
	return !state->solid[kon_tilemapAt(&state->map, column, row)];
}

static void draw(kon_program_t *program, kon_framebuffer_t *game, void *user)
{
	state_t *state = user;
	kon_camera_t camera = kon_cameraDefault();
	kon_light_t light = kon_lightDefault();
	kon_material_t brick = kon_materialTexture(state->brick), floor = kon_materialTexture(state->floor);
	kon_vec3_t eye = KON_VEC3((state->player.x + state->player.w * 0.5f) / TILE, 0.6f, (state->player.y + state->player.h * 0.5f) / TILE);
	kon_mat4_t vp;
	int row, column, i;
	float size = (float)COLUMNS;

	camera.position = eye;
	camera.target = KON_VEC3(eye.x + sinf(state->yaw) * cosf(state->pitch), eye.y + sinf(state->pitch), eye.z - cosf(state->yaw) * cosf(state->pitch));
	camera.nearZ = 0.05f;
	camera.farZ = 40.0f;
	vp = kon_cameraViewProjection(&camera, game->width, game->height);

	kon_clearFramebuffer(game, COL_SKY);
	light.direction = KON_VEC3(-0.3f, -1.0f, -0.5f);
	light.ambient = 0.55f;

	for (row = 0; row < ROWS; row++) {
		for (column = 0; column < COLUMNS; column++) {
			float x = (float)column, z = (float)row;

			if (open(state, column, row)) continue;
			if (open(state, column, row - 1)) wall(game, vp, &brick, &light, KON_VEC3(x + 1, 0, z), KON_VEC3(x, 0, z), KON_VEC3(0, 0, -1));
			if (open(state, column, row + 1)) wall(game, vp, &brick, &light, KON_VEC3(x, 0, z + 1), KON_VEC3(x + 1, 0, z + 1), KON_VEC3(0, 0, 1));
			if (open(state, column - 1, row)) wall(game, vp, &brick, &light, KON_VEC3(x, 0, z), KON_VEC3(x, 0, z + 1), KON_VEC3(-1, 0, 0));
			if (open(state, column + 1, row)) wall(game, vp, &brick, &light, KON_VEC3(x + 1, 0, z + 1), KON_VEC3(x + 1, 0, z), KON_VEC3(1, 0, 0));
		}
	}

	/* the big flat quads go after the walls, what a wall already covers gets thrown out by the depth test early */
	quad(game, vp, &floor, &light, KON_VEC3(0, 0, 0), KON_VEC3(0, 0, size), KON_VEC3(size, 0, size), KON_VEC3(size, 0, 0),
		KON_VEC3(0, 1, 0), KON_VEC2(0, 0), KON_VEC2(size, size));
	quad(game, vp, &floor, &light, KON_VEC3(0, WALL_HEIGHT, 0), KON_VEC3(size, WALL_HEIGHT, 0), KON_VEC3(size, WALL_HEIGHT, size), KON_VEC3(0, WALL_HEIGHT, size),
		KON_VEC3(0, -1, 0), KON_VEC2(0, 0), KON_VEC2(size, size));

	for (i = 0; i < MARKERS; i++) {
		float dx = state->markers[i].x - eye.x, dz = state->markers[i].y - eye.z;
		float bob = 0.08f * sinf((float)state->time * 2.0f + (float)i);
		float brightness = 1.0f / (1.0f + sqrtf(dx * dx + dz * dz) * 0.18f);

		kon_drawBillboard(game, vp, KON_VEC3(state->markers[i].x, 0.1f + bob, state->markers[i].y), 0.6f, 0.75f, state->marker, KON_RECT(0, 0, 0, 0), brightness, KON_RENDER_DEPTH);
	}

	if (program->font) kon_drawText(game, program->font, 8, 16, "click to look with the mouse, tab lets go", COL_DIM);
}

/*** program ***/

static int event(kon_program_t *program, const kon_event_t *ev, void *user)
{
	state_t *state = user;
	int down;

	if (ev->type == KON_EVENT_MOUSE_MOVE && kon_isMouseCaptured(program->window)) {
		state->yaw += (float)ev->mouseDX * state->sensitivity;
		state->pitch -= (float)ev->mouseDY * state->sensitivity;
		if (state->pitch > 1.2f) state->pitch = 1.2f;
		if (state->pitch < -1.2f) state->pitch = -1.2f;
		return 1;
	}
	if (ev->type == KON_EVENT_MOUSE_DOWN && !kon_isMouseCaptured(program->window)) {
		kon_setMouseCapture(program->window, true);
		return 1;
	}
	if (ev->type == KON_EVENT_KEY_DOWN && ev->key == KON_KEY_TAB) {
		kon_setMouseCapture(program->window, !kon_isMouseCaptured(program->window));
		return 1;
	}
	if (ev->type != KON_EVENT_KEY_DOWN && ev->type != KON_EVENT_KEY_UP) return 0;
	down = ev->type == KON_EVENT_KEY_DOWN;

	switch (ev->key) {
	case KON_KEY_W: case KON_KEY_UP: state->forward = down ? 1 : (state->forward > 0 ? 0 : state->forward); break;
	case KON_KEY_S: case KON_KEY_DOWN: state->forward = down ? -1 : (state->forward < 0 ? 0 : state->forward); break;
	case KON_KEY_D: state->strafe = down ? 1 : (state->strafe > 0 ? 0 : state->strafe); break;
	case KON_KEY_A: state->strafe = down ? -1 : (state->strafe < 0 ? 0 : state->strafe); break;
	case KON_KEY_RIGHT: state->turn = down ? 1 : (state->turn > 0 ? 0 : state->turn); break;
	case KON_KEY_LEFT: state->turn = down ? -1 : (state->turn < 0 ? 0 : state->turn); break;
	default: return 0;
	}
	return 1;
}

static void update(kon_program_t *program, double dt, void *user)
{
	state_t *state = user;
	float speed = 2.5f * (float)dt * TILE;
	float fx = sinf(state->yaw), fz = -cosf(state->yaw);
	float dx = (fx * (float)state->forward - fz * (float)state->strafe) * speed;
	float dz = (fz * (float)state->forward + fx * (float)state->strafe) * speed;

	/* the console needs the cursor back */
	if (kon_debugConsoleOpen(program->debug) && kon_isMouseCaptured(program->window)) kon_setMouseCapture(program->window, false);

	state->time += dt;
	state->yaw += (float)state->turn * 2.0f * (float)dt;
	kon_tilemapMove(&state->map, &state->player, dx, dz, state->solid, 2);
}

static int init(kon_program_t *program, void *user)
{
	state_t *state = user;
	static const kon_vec2_t spots[MARKERS] = { { 3.5f, 6.5f }, { 12.5f, 3.5f }, { 8.0f, 13.0f }, { 5.5f, 11.5f }, { 11.5f, 7.5f } };
	int row, column, i;

	(void)program;
	state->sensitivity = 0.0015f;
	kon_debugVar(program->debug, "sens", KON_VAR_FLOAT, &state->sensitivity);
	state->map.columns = COLUMNS;
	state->map.rows = ROWS;
	state->map.tileWidth = TILE;
	state->map.tileHeight = TILE;
	state->map.tiles = state->tiles;
	state->solid[1] = 1;
	for (row = 0; row < ROWS; row++) {
		for (column = 0; column < COLUMNS; column++) state->tiles[row * COLUMNS + column] = level[row][column] == '#';
	}

	state->brick = makeBrick();
	state->floor = makeFloor();
#if defined(KON_MODULE_ASSETS) && defined(KON_MODULE_IMAGE)
	if (program->assets) state->marker = kon_assetImage(program->assets, "sprites/marker.png");
#endif
	if (!state->marker) {
		state->marker = makeMarker();
		state->ownsMarker = 1;
	}
	if (!state->brick || !state->floor || !state->marker) return 0;

	state->player = KON_BOX2(1.5f * TILE, 13.5f * TILE, 12, 12);
	for (i = 0; i < MARKERS; i++) state->markers[i] = spots[i];
	return 1;
}

static void shutdown(kon_program_t *program, void *user)
{
	state_t *state = user;

	(void)program;
	kon_freeFramebuffer(state->brick);
	kon_freeFramebuffer(state->floor);
	if (state->ownsMarker) kon_freeFramebuffer(state->marker);
}

int main(void)
{
	state_t state = {0};
	kon_programConfig_t config = {0};

	config.title = "corridor";
	config.gameWidth = 480;
	config.gameHeight = 270;
	config.windowWidth = 960;
	config.windowHeight = 540;
	config.user = &state;
	config.init = init;
	config.event = event;
	config.update = update;
	config.draw = draw;
	config.shutdown = shutdown;
	return kon_programRun(&config);
}