// Voir README.md pour license précise, par Fcalva 2023-2024 et est sous GPLv3

#include <math.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <time.h>

#include <gint/display.h>
#include <gint/display-fx.h>
#include <gint/keyboard.h>
#include <gint/gray.h>
#include <libprof.h>

#include "fixed.h"

#include "moteur.h"
#include "map.h"
#include "game.h"
#include "config.h"

// moteur.c :
// ici se trouvent tout ce qui concerne les graphismes, mouvement et collisions
//

//1D zbuf for sprites
fixed_t zbuf[viewport_w];

void move(RcGame *game) {
  extern int frame_time;
  fixed_t moveSpeed = fmul(fix(frame_time), 0x148); //frame_time * fix(carrés/seconde/1000) là carrés/seconde = 5
  fixed_t rotSpeed = fmul(fix(frame_time), 0x83); //frame_time * fix(radians/seconde/1000) là radians/seconde = 2
  fixed_t c_rotSpeed = fix(cos(f2float(rotSpeed)));
  fixed_t s_rotSpeed = fix(sin(f2float(rotSpeed)));

  uint8_t *map_test = game->current_map->dat;
  V2d *plane = &game->player.plane;
  V2d *dir = &game->player.dir;
  V2d *pos = &game->player.pos;

  fixed_t oldDirX;
  fixed_t oldPlaneX;
  int xtemp1;
  int ytemp1;
  int xtemp2;
  int ytemp2;

  if (keydown(KEY_UP)) {
    xtemp1 = ffloor(pos->x + fmul(dir->x, moveSpeed));
    ytemp1 = ffloor(pos->y);
    xtemp2 = ffloor(pos->x);
    ytemp2 = ffloor(pos->y + fmul(dir->y, moveSpeed));

    if(!map_test[xtemp1*map_w+ytemp1])
      pos->x += fmul(dir->x, moveSpeed);
    if(!map_test[xtemp2*map_w+ytemp2])
      pos->y += fmul(dir->y, moveSpeed);
  }
  //move backwards if no wall behind you
  if (keydown(KEY_DOWN)) {
    xtemp1 = ffloor(pos->x - fmul(dir->x, moveSpeed));
    ytemp1 = ffloor(pos->y);
    xtemp2 = ffloor(pos->x);
    ytemp2 = ffloor(pos->y - fmul(dir->y, moveSpeed));

    if(!map_test[xtemp1*map_w+ytemp1])
      pos->x -= fmul(dir->x, moveSpeed);
    if(!map_test[xtemp2*map_w+ytemp2])
      pos->y -= fmul(dir->y, moveSpeed);
  }
  //rotate to the right
  if (keydown(KEY_RIGHT)) {
    //both camera direction and camera plane must be rotated
    oldDirX = dir->x;
    dir->x = (fmul(dir->x, c_rotSpeed)+1) - (fmul(dir->y, -s_rotSpeed)+1);
    dir->y = (fmul(oldDirX, -s_rotSpeed)+1) + (fmul(dir->y, c_rotSpeed)+1);
    oldPlaneX = plane->x;
    plane->x = (fmul(plane->x, c_rotSpeed)+1) - (fmul(plane->y, -s_rotSpeed)+1);
    plane->y = (fmul(oldPlaneX, -s_rotSpeed)+1) + (fmul(plane->y, c_rotSpeed)+1);
  }
  //rotate to the left
  if (keydown(KEY_LEFT)) {
    //both camera direction and camera plane must be rotated
    oldDirX = dir->x;
    dir->x = (fmul(dir->x, c_rotSpeed)-1) - (fmul(dir->y, s_rotSpeed)-1);
    dir->y = (fmul(oldDirX, s_rotSpeed)+1) + (fmul(dir->y, c_rotSpeed)+1);
    oldPlaneX = plane->x;
    plane->x = (fmul(plane->x, c_rotSpeed)-1) - (fmul(plane->y, s_rotSpeed) - 1);
    plane->y = (fmul(oldPlaneX, s_rotSpeed)+1) + (fmul(plane->y, c_rotSpeed) + 1);
  }

  if (dir->x > 0xFFFF) dir->x = 0xFFFF;
  if (dir->y > 0xFFFF) dir->y = 0xFFFF;
  if (dir->x < -0xFFFF) dir->x = -0xFFFF;
  if (dir->y < -0xFFFF) dir->y = -0xFFFF;
}

void load_map(){

}

//Fonction fournie par le grand Lephé :D
inline int __attribute__((always_inline))
  get_pixel(bopti_image_t const *img, int u, int v)
{
  int layers = image_layer_count(img->profile);
  int columns = (img->width + 31) >> 5;

  uint32_t const *layer_ptr = (void *)img->data;
  layer_ptr += (v * columns + (u >> 5)) * layers;

  uint32_t mask = 0x80000000u >> (u & 31);

  int light = (layer_ptr[0] & mask) != 0;
  int dark  = (layer_ptr[1] & mask) != 0;
  int alpha = 0;
  if(layers > 2){
    alpha = !(layer_ptr[2] & mask);
  }
  return (alpha << 2) + (dark << 1) + light;
}

uint32_t *light, *dark;

//Version simplifiée de gpixel dans gint/src/gray/gpixel.c
//Tout le crédit revient à Lephé
inline void __attribute__((always_inline))
  cust_dpixel(int x, int y, color_t color){

  if(y >= viewport_h || y < 0)
    return;
  int offset = (y << 2) + (x >> 5);
  uint32_t mask = 1 << (~x & 31);

  switch(color){
    case C_WHITE:
      light[offset] &= ~mask;
      dark [offset] &= ~mask;
      break;

    case C_LIGHT:
      light[offset] |= mask;
      dark [offset] &= ~mask;
      break;

    case C_DARK:
      light[offset] &= ~mask;
      dark [offset] |= mask;
      break;

    case C_BLACK:
      light[offset] |= mask;
      dark [offset] |= mask;
      break;
    case C_NONE:
      break;

    default: break;
  }
}

void dscale_bopti(bopti_image_t *tex, fixed_t scale_x, fixed_t scale_y, int x, int y){
  dgray_getvram(&light,&dark);

  fixed_t screen_y = fix(y);
  fixed_t tex_y = 0;
  do{
    fixed_t oldy = screen_y;
    if(screen_y < 0 || screen_y+scale_x > viewport_h)
      return;
    do{
      fixed_t screen_x = fix(x);
      fixed_t tex_x = 0;
      do{
        fixed_t oldx = screen_x;
        int tpix = get_pixel(tex, tex_x, tex_y);
        if(screen_x < 0 || screen_x+scale_x > viewport_w)
          return;
        do{
          cust_dpixel(ffloor(oldx), ffloor(oldy), tpix);
          oldx += 0xFFFF;
        } while(oldx < screen_x+scale_x);
        screen_x += scale_x;
        tex_x++;
      } while(tex_x < tex->width);
      oldy += 0xFFFF;
    } while(oldy < screen_y+scale_y);
    screen_y += scale_y;
    tex_y++;
  } while(tex_y < tex->height);
}

inline void __attribute__((always_inline))
  draw_stripe(bopti_image_t *tex, int texSampleY, int linePos, fixed_t texSize,
                int texX, int x){

    fixed_t screenPos = fix(linePos);
    for(int texPos = texSampleY; texPos < TSIZE; ++texPos){
      if(screenPos >= 0){
        fixed_t oldPos = screenPos;
        int tpix = get_pixel(tex, texX, texPos);
        do{
          oldPos += 0xFFFF;
          cust_dpixel(x, fround(oldPos), tpix);
        } while(oldPos < screenPos+texSize);
      }
      screenPos += texSize;
    }
}

void draw_walls(
#if debug
  EngineTimers *timers,
#endif
  RcGame *game
){
    fixed_t posX = game->player.pos.x;
    fixed_t posY = game->player.pos.y;
    fixed_t dirX = game->player.dir.x;
    fixed_t dirY = game->player.dir.y;
    fixed_t planeX = game->player.plane.x;
    fixed_t planeY = game->player.plane.y;
    extern bopti_image_t *tex_index[TINDEX_S];
    uint8_t *map_test = game->current_map->dat;

    fixed_t cameraX;
    fixed_t rayDirX;
    fixed_t rayDirY;
    fixed_t sideDistX;//length of ray from current position to next x or y-side
    fixed_t sideDistY;
    fixed_t deltaDistX;
    fixed_t deltaDistY;
    fixed_t perpWallDist;
    int x;
    int mapX;
    int mapY;
    int stepX; //what direction to step in x or y-direction (either +1 or -1)
    int stepY;
    int side = 0; //was a NS or a EW wall hit?
    int lineHeight;
    int texX;
    int texSample;
    int texSampleY;

    dgray_getvram(&light,&dark);

    //int v_offset = 0;
    fixed_t h_offset = 0;

    //struct image_linear_map temp;

    for(x = 0; x < viewport_w; x++) {
      #if debug
      prof_enter(timers->raycast_time);
      #endif

      //calculate ray position and direction
      cameraX = fdiv(fix(x*2), fix(viewport_w)) - 0xFFFF + h_offset; //x-coordinate in camera space
      
      rayDirX = dirX + fmul(planeX, cameraX);
      rayDirY = dirY + fmul(planeY, cameraX);
      
      //which box of the map we're in
      mapX = ffloor(posX);
      mapY = ffloor(posY);

      // length of ray from one x or y-side to next x or y-side
      // these are derived as:
      // deltaDistX = sqrt(1 + (rayDirY * rayDirY) / (rayDirX * rayDirX))
      // deltaDistY = sqrt(1 + (rayDirX * rayDirX) / (rayDirY * rayDirY))
      // which can be simplified to abs(|rayDir| / rayDirX) and abs(|rayDir| / rayDirY)
      // where |rayDir| is the length of the vector (rayDirX, rayDirY). Its length,
      // unlike (dirX, dirY) is not 1, however this does not matter, only the
      // ratio between deltaDistX and deltaDistY matters, due to the way the DDA
      // stepping further below works. So the values can be computed as below.
      // Division through zero is prevented, even though technically that's not
      // needed in C++ with IEEE 754 floating point values. 
      //Fcalva : It is with fp32s !

      rayDirX = rayDirX == 0 ? 1 : rayDirX;
      rayDirY = rayDirY == 0 ? 1 : rayDirY;

      deltaDistX = abs(fdiv(0xFFFF, rayDirX));
      deltaDistY = abs(fdiv(0xFFFF, rayDirY));
      if(deltaDistX > max_dist) deltaDistX = max_dist;
      if(deltaDistY > max_dist) deltaDistY = max_dist;

      //calculate step and initial sideDist
      if (rayDirX < 0) {
        stepX = -1;
        sideDistX = fmul(posX - fix(mapX), deltaDistX);
      }
      else {
        stepX = 1;
        sideDistX = fmul( fix(mapX + 1) - posX, deltaDistX);
      }

      if (rayDirY == 0) {
        stepY = 0;
        sideDistY = 0;
      }
      else if (rayDirY < 0) {
        stepY = -1;
        sideDistY = fmul(posY - fix(mapY), deltaDistY);
      }
      else {
        stepY = 1;
        sideDistY = fmul( fix(mapY + 1) - posY, deltaDistY);
      }
      //perform DDA
      while(true) {
        //Check if the ray is out of range/bounds
        if (sideDistX >= max_dist || sideDistY >= max_dist || mapX < 0 || mapY < 0 || mapY >= map_w || mapX >= map_h) {
          break;
        }
        //Otherwise check if ray has hit a wall
        if (map_test[mapX*map_w+mapY] > 0) {
          break;
        }
        //jump to next map square, either in x-direction, or in y-direction
        if (sideDistX < sideDistY) {
          sideDistX += deltaDistX; 
          mapX += stepX; 
          side = 0;
        }
        else {
          sideDistY += deltaDistY;
          mapY += stepY; 
          side = 1;
        }
      }
      //Calculate distance projected on camera direction. This is the shortest distance from the point where the wall is
      //hit to the camera plane. Euclidean to center camera point would give fisheye effect!
      //This can be computed as (mapX - posX + (1 - stepX) / 2) / rayDirX for side == 0, or same formula with Y
      //for size == 1, but can be simplified to the code below thanks to how sideDist and deltaDist are computed:
      //because they were left scaled to |rayDir|. sideDist is the entire length of the ray above after the multiple
      //steps, but we subtract deltaDist once because one step more into the wall was taken above.

      if (side == 0) perpWallDist = (sideDistX - deltaDistX);
      else perpWallDist = (sideDistY - deltaDistY);

      zbuf[x] = perpWallDist;

      #if debug
      prof_leave(timers->raycast_time);
      prof_enter(timers->draw_time);
      #endif

      //texturing calculations

      //calculate value of wallX
      fixed_t wallX; //where exactly the wall was hit
      if (side == 0) wallX = posY + fmul(perpWallDist, rayDirY); 
      else  wallX = posX + fmul(perpWallDist, rayDirX);     
      wallX -= fix(ffloor(wallX));

      //x coordinate on the texture
      texX = fmul(wallX, TSIZE);
      texX %= TSIZE;

      if(side == 0 && rayDirX > 0) texX = 64 - texX - 1;
      if(side == 1 && rayDirY < 0) texX = 64 - texX - 1;

      lineHeight = ffloor(fdiv(fix(viewport_h), perpWallDist)); //Taille en px de la ligne
      if (lineHeight < 1) lineHeight = 1;
      //if (lineHeight > viewport_h) lineHeight = viewport_h - 1;

      fixed_t texSize = fix(lineHeight) / TSIZE; //taille proportionelle de la ligne a la tex
      if (texSize < fix(1.0/(float)TSIZE)) texSize = fix(1.0/(float)TSIZE);
      if (texSize > fix((float)viewport_h/(float)TSIZE)) {
        texSample = fceil(fdiv(fix(viewport_h), texSize));
        texSampleY  = TSIZE/2 - texSample/2;
      }
      else {
        texSample = TSIZE;
        texSampleY = 0; 
      }

      int linePos = viewport_h/2 - lineHeight/2;

      bopti_image_t *tex = tex_index[map_test[mapX*map_w+mapY]];

      //dline(x, linePos, x, linePos + lineHeight, 1);

      draw_stripe(tex, texSampleY, linePos,
                    texSize, texX, x);

      #if debug
      prof_leave(timers->draw_time);
      #endif
  }
}