/*
 * platform: a box that runs and jumps around a tilemap, and a ray that follows the mouse
 *
 * build:  ./build.sh -d -m tile,font obj/platform
 * run:    obj/platform
 *
 * left and right or a and d run, space or up jumps. the line from the box to the mouse stops at the first solid tile
 * the console is not needed, but with the debug module the grave key opens it and the variables gravity and jump are there
 */

#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/platform"
#endif

#define TILE 16
#define COLUMNS 40
#define ROWS 22
#define STEP (1.0 / 120.0)

#define COL_BACKGROUND 0xFF1B1826u
#define COL_TILE       0xFF4A4468u
#define COL_TILE_TOP   0xFF6B5F92u
#define COL_PLAYER     0xFFF2A7C3u
#define COL_RAY        0xFF8FD3C8u
#define COL_HIT        0xFFF3DDA0u
#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_box2_t player;
	kon_vec2_t velocity;
	int onGround;
	double leftover, coyote;
	int left, right, jumpHeld;
	float gravity, jump;

	int mouseX, mouseY;
	int rayHit;
	kon_hit2_t hit;
} state_t;

/*** program ***/

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

	if (ev->type == KON_EVENT_MOUSE_MOVE) {
		kon_windowToGame(program->display, ev->mouseX, ev->mouseY, &state->mouseX, &state->mouseY);
	} else if (ev->type == KON_EVENT_KEY_DOWN || ev->type == KON_EVENT_KEY_UP) {
		int down = ev->type == KON_EVENT_KEY_DOWN;

		if (ev->key == KON_KEY_LEFT || ev->key == KON_KEY_A) state->left = down;
		else if (ev->key == KON_KEY_RIGHT || ev->key == KON_KEY_D) state->right = down;
		else if (ev->key == KON_KEY_SPACE || ev->key == KON_KEY_UP) state->jumpHeld = down;
		else return 0;
	} else {
		return 0;
	}
	return 1;
}

static void step(state_t *state, float dt)
{
	float run = (float)(state->right - state->left) * 120.0f;
	int flags;

	state->velocity.x += (run - state->velocity.x) * (state->onGround ? 18.0f : 8.0f) * dt;
	state->velocity.y += state->gravity * dt;

	if (state->coyote > 0.0) state->coyote -= dt;
	if (state->jumpHeld && state->coyote > 0.0) {
		state->velocity.y = -state->jump;
		state->coyote = 0.0;
	}
	/* letting go early cuts the jump short */
	if (!state->jumpHeld && state->velocity.y < -60.0f) state->velocity.y = -60.0f;

	flags = kon_tilemapMove(&state->map, &state->player, state->velocity.x * dt, state->velocity.y * dt, state->solid, 2);

	if (flags & (KON_HIT_LEFT | KON_HIT_RIGHT)) state->velocity.x = 0.0f;
	if (flags & (KON_HIT_UP | KON_HIT_DOWN)) state->velocity.y = 0.0f;
	state->onGround = (flags & KON_HIT_DOWN) != 0;
	if (state->onGround) state->coyote = 0.08;
}

static void update(kon_program_t *program, double dt, void *user)
{
	state_t *state = user;
	kon_vec2_t from = KON_VEC2(state->player.x + state->player.w * 0.5f, state->player.y + state->player.h * 0.5f);
	kon_vec2_t dir = KON_VEC2((float)state->mouseX - from.x, (float)state->mouseY - from.y);
	float length = kon_vec2Length(dir);
	int row, column;

	(void)program;
	state->leftover += dt;
	while (state->leftover >= STEP) {
		step(state, (float)STEP);
		state->leftover -= STEP;
	}

	/* the ray against every solid tile, nothing clever, the nearest one wins */
	state->rayHit = 0;
	if (length < 1.0f) return;
	dir = kon_vec2Scale(dir, 1.0f / length);
	for (row = 0; row < ROWS; row++) {
		for (column = 0; column < COLUMNS; column++) {
			kon_hit2_t hit;

			if (!state->solid[kon_tilemapAt(&state->map, column, row)]) continue;
			if (!kon_rayBox(from, dir, length, KON_BOX2(column * TILE, row * TILE, TILE, TILE), &hit)) continue;
			if (!state->rayHit || hit.time < state->hit.time) {
				state->hit = hit;
				state->rayHit = 1;
			}
		}
	}
}

static void draw(kon_program_t *program, kon_framebuffer_t *game, void *user)
{
	state_t *state = user;
	int row, column, ex, ey;
	int fromX = (int)(state->player.x + state->player.w * 0.5f), fromY = (int)(state->player.y + state->player.h * 0.5f);

	kon_clearFramebuffer(game, COL_BACKGROUND);

	for (row = 0; row < ROWS; row++) {
		for (column = 0; column < COLUMNS; column++) {
			if (!state->solid[kon_tilemapAt(&state->map, column, row)]) continue;
			kon_fillRectangle(game, column * TILE, row * TILE, TILE, TILE, COL_TILE);
			if (!state->solid[kon_tilemapAt(&state->map, column, row - 1)]) kon_fillRectangle(game, column * TILE, row * TILE, TILE, 2, COL_TILE_TOP);
		}
	}

	ex = state->rayHit ? (int)state->hit.point.x : state->mouseX;
	ey = state->rayHit ? (int)state->hit.point.y : state->mouseY;
	kon_drawLine(game, fromX, fromY, ex, ey, COL_RAY);
	if (state->rayHit) kon_fillCircle(game, ex, ey, 2, COL_HIT);

	kon_fillRectangle(game, (int)state->player.x, (int)state->player.y, (int)state->player.w, (int)state->player.h, COL_PLAYER);

	if (program->font) kon_drawText(game, program->font, 24, 40, "arrows or a d to run, space to jump", COL_DIM);
}

static int init(kon_program_t *program, void *user)
{
	state_t *state = user;
	int row, column;

	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->player = KON_BOX2(40, 280, 10, 14);
	state->gravity = 700.0f;
	state->jump = 260.0f;

	kon_debugVar(program->debug, "gravity", KON_VAR_FLOAT, &state->gravity);
	kon_debugVar(program->debug, "jump", KON_VAR_FLOAT, &state->jump);
	return 1;
}

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

	config.title = "platform";
	config.gameWidth = 640;
	config.gameHeight = 352;
	config.windowWidth = 1280;
	config.windowHeight = 704;
	config.user = &state;
	config.init = init;
	config.event = event;
	config.update = update;
	config.draw = draw;
	return kon_programRun(&config);
}