#include "hitomezashi.h"
#include "SDL.h"
#include <assert.h>

SDL_Color HITOMEZASHI_FG_COLOUR = { .r = 0,	.g = 0,		.b = 0		};
SDL_Color HITOMEZASHI_BG_COLOUR = { .r = 255,	.g = 255,	.b = 255	};

enum Hitomezashi_State_Init_Result
hitomezashi_state_init(
			struct Hitomezashi_State *state,
			int x_pattern_len, int y_pattern_len,
			char *x_pattern, char *y_pattern,
			int gap, int line_thickness) {
	assert(x_pattern_len >= 0);
	assert(y_pattern_len >= 0);
	assert(gap >= 0);
	assert(line_thickness > 0);

	state->y_pattern_len = y_pattern_len;
	state->x_pattern_len = x_pattern_len;
	state->x_pattern = x_pattern;
	state->y_pattern = y_pattern;
	state->gap = gap;
	state->line_thickness = line_thickness;
	state->output_width = x_pattern_len * gap;
	state->output_height = y_pattern_len * gap;

	state->surface = SDL_CreateRGBSurface(0, state->output_width, state->output_height, 32, 0, 0, 0, 0);
	if (!state->surface) {
		return Hitomezashi_State_Init_Result_Err_Create_Surface;
	}
	return Hitomezashi_State_Init_Result_Success;
}

enum Hitomezashi_Draw_Result
hitomezashi_draw(struct Hitomezashi_State *state) {
	if (SDL_LockSurface(state->surface) != 0) {
		return Hitomezashi_Draw_Result_Err_Lock_Surface;
	}

	Uint32 bg_colour = SDL_MapRGB(state->surface->format, HITOMEZASHI_BG_COLOUR.r, HITOMEZASHI_BG_COLOUR.g, HITOMEZASHI_BG_COLOUR.b);
	Uint32 fg_colour = SDL_MapRGB(state->surface->format, HITOMEZASHI_FG_COLOUR.r, HITOMEZASHI_FG_COLOUR.g, HITOMEZASHI_FG_COLOUR.b);

	SDL_FillRect(state->surface, NULL, bg_colour);

	SDL_Rect rect;
	// Draw y pattern (horizontal) lines
	for (int i = 0; i < state->y_pattern_len; ++i) {
		for (int j = 0; j < state->x_pattern_len; ++j) {
			if (j % 2 == state->y_pattern[i]) {
				rect.x = j * state->gap;
				rect.y = i * state->gap;
				rect.w = state->gap;
				rect.h = state->line_thickness;
				SDL_FillRect(state->surface, &rect, fg_colour);
			}
		}
	}
	// Draw x pattern (vertical) lines
	for (int i = 0; i < state->x_pattern_len; ++i) {
		for (int j = 0; j < state->y_pattern_len; ++j) {
			if (j % 2 == state->x_pattern[i]) {
				rect.x = i * state->gap;
				rect.y = j * state->gap;
				rect.w = state->line_thickness;
				rect.h = state->gap;
				SDL_FillRect(state->surface, &rect, fg_colour);
			}
		}
	}
	// Join up the lines to avoid leaving holes at the intersections
	for (int x = state->gap; x < state->output_width; x += state->gap) {
		for (int y = state->gap; y < state->output_height; y += state->gap) {
				rect.x = x;
				rect.y = y;
				rect.w = state->line_thickness;
				rect.h = state->line_thickness;
				SDL_FillRect(state->surface, &rect, fg_colour);

		}
	}

	SDL_UnlockSurface(state->surface);
	return Hitomezashi_Draw_Result_Success;
}