#include "font.h"
#include "EGA8x8.h"

#include <stdio.h>
#include <SDL.h>

#define SWAP(a, b) ({ \
    __typeof(a) tmp = (a); \
    (a) = (b); \
    (b) = tmp; \
})

typedef struct {
    int x1;
    int y1;
    int x2;
    int y2;
    int w;
    int h;
    SDL_Surface *surface;
    SDL_Texture *texture;
    uint32_t *pixels;
    uint32_t color;
} Picture;

static void Picture_render(Picture *p, SDL_Renderer *rend);
static Picture *Picture_new(SDL_Renderer *rend,
    int x, int y, int w, int h, uint32_t color) {
    
    Picture *p = calloc(1, sizeof(Picture));

    p->x1 = x;
    p->x2 = x + w;
    p->y1 = y;
    p->y2 = y + h;
    p->w = w;
    p->h = h;
    p->pixels = malloc(w * h * sizeof(uint32_t));
    p->color = color;

    p->surface = SDL_CreateRGBSurfaceWithFormatFrom(
        p->pixels, w, h, 32, w * sizeof(uint32_t),
        SDL_PIXELFORMAT_RGBA32);

    Picture_render(p, rend);
    return p;
}

typedef uint32_t uint32_8 __attribute__ ((vector_size (8 * sizeof(uint32_t))));

static void Picture_render(Picture *p, SDL_Renderer *rend) {
    uint32_8 c = p->color - (uint32_8){};
    uint32_8 y = 0 - (uint32_8){};
    for (int j = p->y1, r = 0; j < p->y2; j++, y+=1) {
        uint32_8 x = {0, 1, 2, 3, 4, 5, 6, 7};
        for (int i = p->x1; i < p->x2; i+=8, r+=8, x+=8) {
            uint32_8 z = (x ^ y) % 9;
            uint32_8 f = (z==0) & c;
            memcpy(&p->pixels[r], (uint32_t*)&f, sizeof(f));
        }
    }
    if (p->texture) SDL_DestroyTexture(p->texture);
    p->texture = SDL_CreateTextureFromSurface(rend, p->surface);
    SDL_SetTextureBlendMode(p->texture, SDL_BLENDMODE_NONE);
}

static void Picture_move(Picture *p, int x, int y) {
    p->x1 += x;
    p->x2 += x;
    p->y1 += y;
    p->y2 += y;
}

struct int2 { int x; int y; };

int main() {

    int w = 1280, h = 720;

    if (SDL_Init(SDL_INIT_VIDEO) != 0) {
        fprintf(stderr, "Can't init: %s\n", SDL_GetError());
        return -1;
    }

    SDL_Window *window = SDL_CreateWindow("xormod",
        SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, w, h,
        SDL_WINDOW_OPENGL /*SDL_WINDOW_FULLSCREEN */);
    if (window == NULL) {
        fprintf(stderr, "Can't open window: %s\n", SDL_GetError());
        return -1;
    }

    SDL_GetWindowSize(window, &w, &h);

    SDL_Renderer *rend = SDL_CreateRenderer(window, -1,
        /*SDL_RENDERER_PRESENTVSYNC | */SDL_RENDERER_ACCELERATED);

    SDL_Texture *font = load_font(rend);

    Picture *pictures[4];
    enum { P_TOPLEFT, P_TOPRGHT, P_BOTLEFT, P_BOTRGHT };

    pictures[P_TOPLEFT] = Picture_new(rend, 0, 0, w, h, 0xff7fffff);
    pictures[P_TOPRGHT] = Picture_new(rend, w, 0, w, h, 0xffff7fff);
    pictures[P_BOTLEFT] = Picture_new(rend, 0, h, w, h, 0xffffff7f);
    pictures[P_BOTRGHT] = Picture_new(rend, w, h, w, h, 0xff7fff7f);

    struct int2 off = { 0,  0 };
    struct int2 mouse_prev = { -1, -1 };
    int running = 1;
    while (running) {
        const uint8_t *keys = SDL_GetKeyboardState(NULL);
        if (keys[SDL_SCANCODE_ESCAPE] || keys[SDL_SCANCODE_Q]) {
            break;
        }
        if (keys[SDL_SCANCODE_LEFT]) {
            off.x -= 5;
        }
        if (keys[SDL_SCANCODE_RIGHT]) {
            off.x += 5;
        }
        if (keys[SDL_SCANCODE_UP]) {
            off.y -= 5;
        }
        if (keys[SDL_SCANCODE_DOWN]) {
            off.y += 5;
        }
        
        struct int2 mouse;
        if (SDL_GetMouseState(&mouse.x, &mouse.y) & SDL_BUTTON(SDL_BUTTON_LEFT)) {
            if (mouse_prev.x != -1 ) {
                off.x -= mouse.x - mouse_prev.x;
                off.y -= mouse.y - mouse_prev.y;
            }
            mouse_prev = mouse;
        } else if (mouse_prev.x != -1) {
            mouse_prev = (struct int2) { -1, -1 };
        }

        if (off.y < pictures[P_TOPLEFT]->y1) {
            SWAP(pictures[P_TOPLEFT], pictures[P_BOTLEFT]);
            SWAP(pictures[P_TOPRGHT], pictures[P_BOTRGHT]);
            Picture_move(pictures[P_TOPLEFT], 0, -2*h);
            Picture_move(pictures[P_TOPRGHT], 0, -2*h);
            Picture_render(pictures[P_TOPLEFT], rend);
            Picture_render(pictures[P_TOPRGHT], rend);
        }
        if (off.x < pictures[P_TOPLEFT]->x1) {
            SWAP(pictures[P_TOPLEFT], pictures[P_TOPRGHT]);
            SWAP(pictures[P_BOTLEFT], pictures[P_BOTRGHT]);
            Picture_move(pictures[P_TOPLEFT], -2*w, 0);
            Picture_move(pictures[P_BOTLEFT], -2*w, 0);
            Picture_render(pictures[P_TOPLEFT], rend);
            Picture_render(pictures[P_BOTLEFT], rend);
        }
        if (off.y > pictures[P_BOTRGHT]->y1) {
            SWAP(pictures[P_TOPLEFT], pictures[P_BOTLEFT]);
            SWAP(pictures[P_TOPRGHT], pictures[P_BOTRGHT]);
            Picture_move(pictures[P_BOTLEFT], 0, 2*h);
            Picture_move(pictures[P_BOTRGHT], 0, 2*h);
            Picture_render(pictures[P_BOTLEFT], rend);
            Picture_render(pictures[P_BOTRGHT], rend);
        }
        if (off.x > pictures[P_BOTRGHT]->x1) {
            SWAP(pictures[P_TOPLEFT], pictures[P_TOPRGHT]);
            SWAP(pictures[P_BOTLEFT], pictures[P_BOTRGHT]);
            Picture_move(pictures[P_TOPRGHT], 2*w, 0);
            Picture_move(pictures[P_BOTRGHT], 2*w, 0);
            Picture_render(pictures[P_TOPRGHT], rend);
            Picture_render(pictures[P_BOTRGHT], rend);
        }

        //SDL_SetRenderDrawColor(rend, 0, 0, 0, 255);
        //SDL_RenderClear(rend);

        for (int i = 0; i < 4; i++) {
            Picture *p = pictures[i];
            SDL_Rect dst = {
                p->x1 - off.x, p->y1 - off.y, w, h,
            };
            SDL_RenderCopy(rend, p->texture, NULL, &dst);
        }

        //char buf[72];
        //SDL_SetRenderDrawColor(rend, 0, 0, 0, 255);
        //SDL_RenderFillRect(rend, &(SDL_Rect) { 0, 0, sizeof(buf)*font_w, 7*font_h });

        //size_t len = snprintf(buf, sizeof(buf), "off.x: %d, off.y: %d", off.x, off.y);
        //draw_text(rend, font, buf, len, RC(1, 1), 255, 255, 255);

        //char *q[] = {"TL", "TR", "BL", "BR"};
        //for (int i = 0; i < 4; i++) {
        //    Picture *p = pictures[i];
        //    len = snprintf(buf, sizeof(buf), "%s| x1: %05d, x2: %05d, y1: %05d, y2: %05d, p: %p",
        //        q[i], p->x1, p->x2, p->y1, p->y2, p);
        //    draw_text(rend, font, buf, len, RC(2+i, 1), 255, 255, 255);
        //}

        SDL_RenderPresent(rend);

        SDL_Event e;
        while (SDL_PollEvent(&e)) {
            if (e.type == SDL_QUIT) {
                running = 0;
            }
        }
    }

    SDL_DestroyRenderer(rend);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;

}