#define _WIN32_WINNT 0x400

#include <assert.h>
#include <windows.h>

// stb.h
#define STB_DEFINE
#include "stb.h"

// stb_gl.h
#define STB_GL_IMPLEMENTATION
#define STB_GLEXT_DEFINE "glext_list.h"
#include "stb_gl.h"

// SDL
#include "sdl.h"
#include "SDL_opengl.h"

// stb_glprog.h
#define STB_GLPROG_IMPLEMENTATION
#define STB_GLPROG_ARB_DEFINE_EXTENSIONS
#include "stb_glprog.h"

// stb_image.h
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

// stb_easy_font.h
#include "stb_easy_font.h" // doesn't require an IMPLEMENTATION

#include "caveview.h"

char *game_name = "caveview";


#define REVERSE_DEPTH


static void print_string(float x, float y, char *text, float r, float g, float b)
{
   static char buffer[99999];
   int num_quads;
   
   num_quads = stb_easy_font_print(x, y, text, NULL, buffer, sizeof(buffer));

   glColor3f(r,g,b);
   glEnableClientState(GL_VERTEX_ARRAY);
   glVertexPointer(2, GL_FLOAT, 16, buffer);
   glDrawArrays(GL_QUADS, 0, num_quads*4);
   glDisableClientState(GL_VERTEX_ARRAY);
}

static float text_color[3];
static float pos_x = 10;
static float pos_y = 10;

static void print(char *text, ...)
{
   char buffer[999];
   va_list va;
   va_start(va, text);
   vsprintf(buffer, text, va);
   va_end(va);
   print_string(pos_x, pos_y, buffer, text_color[0], text_color[1], text_color[2]);
   pos_y += 10;
}

float camang[3], camloc[3] = { 60,22,77 };
float player_zoom = 1.0;
float rotate_view = 0.0;


void camera_to_worldspace(float world[3], float cam_x, float cam_y, float cam_z)
{
   float vec[3] = { cam_x, cam_y, cam_z };
   float t[3];
   float s,c;
   s = (float) sin(camang[0]*3.141592/180);
   c = (float) cos(camang[0]*3.141592/180);

   t[0] = vec[0];
   t[1] = c*vec[1] - s*vec[2];
   t[2] = s*vec[1] + c*vec[2];

   s = (float) sin(camang[2]*3.141592/180);
   c = (float) cos(camang[2]*3.141592/180);
   world[0] = c*t[0] - s*t[1];
   world[1] = s*t[0] + c*t[1];
   world[2] = t[2];
}

// camera worldspace velocity
float cam_vel[3];

int controls;

#define MAX_VEL  150.0f      // blocks per second
#define ACCEL      6.0f
#define DECEL      3.0f

#define STATIC_FRICTION   DECEL
#define EFFECTIVE_ACCEL   (ACCEL+DECEL)

// dynamic friction:
//
//    if going at MAX_VEL, ACCEL and friction must cancel
//    EFFECTIVE_ACCEL = DECEL + DYNAMIC_FRIC*MAX_VEL
#define DYNAMIC_FRICTION  (ACCEL/(float)MAX_VEL)

float view_x_vel = 0;
float view_z_vel = 0;
float pending_view_x;
float pending_view_z;
float pending_view_x;
float pending_view_z;

void process_tick_raw(float dt)
{
   int i;
   float thrust[3] = { 0,0,0 };
   float world_thrust[3];

   // choose direction to apply thrust

   thrust[0] = (controls &  3)== 1 ? EFFECTIVE_ACCEL : (controls &  3)== 2 ? -EFFECTIVE_ACCEL : 0;
   thrust[1] = (controls & 12)== 4 ? EFFECTIVE_ACCEL : (controls & 12)== 8 ? -EFFECTIVE_ACCEL : 0;
   thrust[2] = (controls & 48)==16 ? EFFECTIVE_ACCEL : (controls & 48)==32 ? -EFFECTIVE_ACCEL : 0;

   // @TODO clamp thrust[0] & thrust[1] vector length to EFFECTIVE_ACCEL

   camera_to_worldspace(world_thrust, thrust[0], thrust[1], 0);
   world_thrust[2] += thrust[2];

   for (i=0; i < 3; ++i) {
      float acc = world_thrust[i];
      cam_vel[i] += acc*dt;
   }

   if (cam_vel[0] || cam_vel[1] || cam_vel[2])
   {
      float vel = (float) sqrt(cam_vel[0]*cam_vel[0] + cam_vel[1]*cam_vel[1] + cam_vel[2]*cam_vel[2]);
      float newvel = vel;
      float dec = STATIC_FRICTION + DYNAMIC_FRICTION*vel;
      newvel = vel - dec*dt;
      if (newvel < 0)
         newvel = 0;
      cam_vel[0] *= newvel/vel;
      cam_vel[1] *= newvel/vel;
      cam_vel[2] *= newvel/vel;
   }

   camloc[0] += cam_vel[0] * dt;
   camloc[1] += cam_vel[1] * dt;
   camloc[2] += cam_vel[2] * dt;

   view_x_vel *= (float) pow(0.75, dt);
   view_z_vel *= (float) pow(0.75, dt);

   view_x_vel += (pending_view_x - view_x_vel)*dt*60;
   view_z_vel += (pending_view_z - view_z_vel)*dt*60;

   pending_view_x -= view_x_vel * dt;
   pending_view_z -= view_z_vel * dt;
   camang[0] += view_x_vel * dt;
   camang[2] += view_z_vel * dt;
   camang[0] = stb_clamp(camang[0], -90, 90);
   camang[2] = (float) fmod(camang[2], 360);
}

void process_tick(float dt)
{
   while (dt > 1.0f/60) {
      process_tick_raw(1.0f/60);
      dt -= 1.0f/60;
   }
   process_tick_raw(dt);
}

void update_view(float dx, float dy)
{
   // hard-coded mouse sensitivity, not resolution independent?
   pending_view_z -= dx*300;
   pending_view_x -= dy*700;
}

extern int screen_x, screen_y;
extern int is_synchronous_debug;
float render_time;

extern int chunk_locations, chunks_considered, chunks_in_frustum;
extern int quads_considered, quads_rendered;
extern int chunk_storage_rendered, chunk_storage_considered, chunk_storage_total;
extern int view_dist_in_chunks;
extern int num_threads_active, num_meshes_started, num_meshes_uploaded;
extern float chunk_server_activity;

static Uint64 start_time, end_time; // render time

float chunk_server_status[32];
int chunk_server_pos;

void draw_stats(void)
{
   int i;

   static Uint64 last_frame_time;
   Uint64 cur_time = SDL_GetPerformanceCounter();
   float chunk_server=0;
   float frame_time = (cur_time - last_frame_time) / (float) SDL_GetPerformanceFrequency();
   last_frame_time = cur_time;

   chunk_server_status[chunk_server_pos] = chunk_server_activity;
   chunk_server_pos = (chunk_server_pos+1) %32;

   for (i=0; i < 32; ++i)
      chunk_server += chunk_server_status[i] / 32.0f;

   stb_easy_font_spacing(-0.75);
   pos_y = 10;
   text_color[0] = text_color[1] = text_color[2] = 1.0f;
   print("Frame time: %6.2fms, CPU frame render time: %5.2fms", frame_time*1000, render_time*1000);
   print("Tris: %4.1fM drawn of %4.1fM in range", 2*quads_rendered/1000000.0f, 2*quads_considered/1000000.0f);
   print("Vbuf storage: %dMB in frustum of %dMB in range of %dMB in cache", chunk_storage_rendered>>20, chunk_storage_considered>>20, chunk_storage_total>>20);
   print("Num mesh builds started this frame: %d; num uploaded this frame: %d\n", num_meshes_started, num_meshes_uploaded);
   print("QChunks: %3d in frustum of %3d valid of %3d in range", chunks_in_frustum, chunks_considered, chunk_locations);
   print("Mesh worker threads active: %d", num_threads_active);
   print("View distance: %d blocks", view_dist_in_chunks*16);
   print("%s", glGetString(GL_RENDERER));

   if (is_synchronous_debug) {
      text_color[0] = 1.0;
      text_color[1] = 0.5;
      text_color[2] = 0.5;
      print("SLOWNESS: Synchronous debug output is enabled!");
   }
}

void draw_main(void)
{
   glEnable(GL_CULL_FACE);
   glDisable(GL_TEXTURE_2D);
   glDisable(GL_LIGHTING);
   glEnable(GL_DEPTH_TEST);
   #ifdef REVERSE_DEPTH
   glDepthFunc(GL_GREATER);
   glClearDepth(0);
   #else
   glDepthFunc(GL_LESS);
   glClearDepth(1);
   #endif
   glDepthMask(GL_TRUE);
   glDisable(GL_SCISSOR_TEST);
   glClearColor(0.6f,0.7f,0.9f,0.0f);
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
   glColor3f(1,1,1);
   glFrontFace(GL_CW);
   glEnable(GL_TEXTURE_2D);
   glDisable(GL_BLEND);


   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();

   #ifdef REVERSE_DEPTH
   stbgl_Perspective(player_zoom, 90, 70, 3000, 1.0/16);
   #else
   stbgl_Perspective(player_zoom, 90, 70, 1.0/16, 3000);
   #endif

   // now compute where the camera should be
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   stbgl_initCamera_zup_facing_y();

   glRotatef(-camang[0],1,0,0);
   glRotatef(-camang[2],0,0,1);
   glTranslatef(-camloc[0], -camloc[1], -camloc[2]);

   start_time = SDL_GetPerformanceCounter();
   render_caves(camloc);
   end_time = SDL_GetPerformanceCounter();

   render_time = (end_time - start_time) / (float) SDL_GetPerformanceFrequency();

   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   gluOrtho2D(0,screen_x/2,screen_y/2,0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   glDisable(GL_TEXTURE_2D);
   glDisable(GL_BLEND);
   glDisable(GL_CULL_FACE);
   draw_stats();
}


#pragma warning(disable:4244; disable:4305; disable:4018)

#define SCALE   2

void error(char *s)
{
   SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Error", s, NULL);
   exit(0);
}

void ods(char *fmt, ...)
{
   char buffer[1000];
   va_list va;
   va_start(va, fmt);
   vsprintf(buffer, fmt, va);
   va_end(va);
   SDL_Log("%s", buffer);
}

#define TICKS_PER_SECOND  60

static SDL_Window *window;

extern void draw_main(void);
extern void process_tick(float dt);
extern void editor_init(void);

void draw(void)
{
   draw_main();
   SDL_GL_SwapWindow(window);
}


static int initialized=0;
static float last_dt;

int screen_x,screen_y;

float carried_dt = 0;
#define TICKRATE 60

float tex2_alpha = 1.0;

int raw_level_time;

float global_timer;
int global_hack;

int loopmode(float dt, int real, int in_client)
{
   if (!initialized) return 0;

   if (!real)
      return 0;

   // don't allow more than 6 frames to update at a time
   if (dt > 0.075) dt = 0.075;

   global_timer += dt;

   carried_dt += dt;
   while (carried_dt > 1.0/TICKRATE) {
      if (global_hack) {
         tex2_alpha += global_hack / 60.0f;
         if (tex2_alpha < 0) tex2_alpha = 0;
         if (tex2_alpha > 1) tex2_alpha = 1;
      }
      //update_input();
      // if the player is dead, stop the sim
      carried_dt -= 1.0/TICKRATE;
   }

   process_tick(dt);
   draw();

   return 0;
}

static int quit;

extern int controls;

void active_control_set(int key)
{
   controls |= 1 << key;
}

void active_control_clear(int key)
{
   controls &= ~(1 << key);
}

extern void update_view(float dx, float dy);

void  process_sdl_mouse(SDL_Event *e)
{
   update_view((float) e->motion.xrel / screen_x, (float) e->motion.yrel / screen_y);
}

void process_event(SDL_Event *e)
{
   switch (e->type) {
      case SDL_MOUSEMOTION:
         process_sdl_mouse(e);
         break;
      case SDL_MOUSEBUTTONDOWN:
      case SDL_MOUSEBUTTONUP:
         break;

      case SDL_QUIT:
         quit = 1;
         break;

      case SDL_WINDOWEVENT:
         switch (e->window.event) {
            case SDL_WINDOWEVENT_SIZE_CHANGED:
               screen_x = e->window.data1;
               screen_y = e->window.data2;
               loopmode(0,1,0);
               break;
         }
         break;

      case SDL_KEYDOWN: {
         int k = e->key.keysym.sym;
         int s = e->key.keysym.scancode;
         SDL_Keymod mod;
         mod = SDL_GetModState();
         if (k == SDLK_ESCAPE)
            quit = 1;

         if (s == SDL_SCANCODE_D)   active_control_set(0);
         if (s == SDL_SCANCODE_A)   active_control_set(1);
         if (s == SDL_SCANCODE_W)   active_control_set(2);
         if (s == SDL_SCANCODE_S)   active_control_set(3);
         if (k == SDLK_SPACE)       active_control_set(4); 
         if (s == SDL_SCANCODE_LCTRL)   active_control_set(5);
         if (s == SDL_SCANCODE_S)   active_control_set(6);
         if (s == SDL_SCANCODE_D)   active_control_set(7);
         if (k == '1') global_hack = !global_hack;
         if (k == '2') global_hack = -1;

         #if 0
         if (game_mode == GAME_editor) {
            switch (k) {
               case SDLK_RIGHT: editor_key(STBTE_scroll_right); break;
               case SDLK_LEFT : editor_key(STBTE_scroll_left ); break;
               case SDLK_UP   : editor_key(STBTE_scroll_up   ); break;
               case SDLK_DOWN : editor_key(STBTE_scroll_down ); break;
            }
            switch (s) {
               case SDL_SCANCODE_S: editor_key(STBTE_tool_select); break;
               case SDL_SCANCODE_B: editor_key(STBTE_tool_brush ); break;
               case SDL_SCANCODE_E: editor_key(STBTE_tool_erase ); break;
               case SDL_SCANCODE_R: editor_key(STBTE_tool_rectangle ); break;
               case SDL_SCANCODE_I: editor_key(STBTE_tool_eyedropper); break;
               case SDL_SCANCODE_L: editor_key(STBTE_tool_link); break;
               case SDL_SCANCODE_G: editor_key(STBTE_act_toggle_grid); break;
            }
            if ((e->key.keysym.mod & KMOD_CTRL) && !(e->key.keysym.mod & ~KMOD_CTRL)) {
               switch (s) {
                  case SDL_SCANCODE_X: editor_key(STBTE_act_cut  ); break;
                  case SDL_SCANCODE_C: editor_key(STBTE_act_copy ); break;
                  case SDL_SCANCODE_V: editor_key(STBTE_act_paste); break;
                  case SDL_SCANCODE_Z: editor_key(STBTE_act_undo ); break;
                  case SDL_SCANCODE_Y: editor_key(STBTE_act_redo ); break;
               }
            }
         }
         #endif
         break;
      }
      case SDL_KEYUP: {
         int k = e->key.keysym.sym;
         int s = e->key.keysym.scancode;
         if (s == SDL_SCANCODE_D)   active_control_clear(0);
         if (s == SDL_SCANCODE_A)   active_control_clear(1);
         if (s == SDL_SCANCODE_W)   active_control_clear(2);
         if (s == SDL_SCANCODE_S)   active_control_clear(3);
         if (k == SDLK_SPACE)       active_control_clear(4); 
         if (s == SDL_SCANCODE_LCTRL)   active_control_clear(5);
         if (s == SDL_SCANCODE_S)   active_control_clear(6);
         if (s == SDL_SCANCODE_D)   active_control_clear(7);
         break;
      }
   }
}

static SDL_GLContext *context;

static float getTimestep(float minimum_time)
{
   float elapsedTime;
   double thisTime;
   static double lastTime = -1;
   
   if (lastTime == -1)
      lastTime = SDL_GetTicks() / 1000.0 - minimum_time;

   for(;;) {
      thisTime = SDL_GetTicks() / 1000.0;
      elapsedTime = (float) (thisTime - lastTime);
      if (elapsedTime >= minimum_time) {
         lastTime = thisTime;         
         return elapsedTime;
      }
      // @TODO: compute correct delay
      SDL_Delay(1);
   }
}

void APIENTRY gl_debug(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar *message, const void *param)
{
   ods("%s\n", message);
}

int is_synchronous_debug;
void enable_synchronous(void)
{
   glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS_ARB);
   is_synchronous_debug = 1;
}

void prepare_threads(void);

//void stbwingraph_main(void)
int SDL_main(int argc, char **argv)
{
   SDL_Init(SDL_INIT_VIDEO);

   prepare_threads();

   SDL_GL_SetAttribute(SDL_GL_RED_SIZE  , 8);
   SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
   SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE , 8);
   SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);

   SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_COMPATIBILITY);
   SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
   SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1);

   #ifdef GL_DEBUG
   SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_DEBUG_FLAG);
   #endif

   SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 4);

   screen_x = 1920;
   screen_y = 1080;

   window = SDL_CreateWindow("caveview", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
                                   screen_x, screen_y,
                                   SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE
                             );
   if (!window) error("Couldn't create window");

   context = SDL_GL_CreateContext(window);
   if (!context) error("Couldn't create context");

   SDL_GL_MakeCurrent(window, context); // is this true by default?

   SDL_SetRelativeMouseMode(SDL_TRUE);
   #if defined(_MSC_VER) && _MSC_VER < 1300
   // work around broken behavior in VC6 debugging
   if (IsDebuggerPresent())
      SDL_SetHint(SDL_HINT_MOUSE_RELATIVE_MODE_WARP, "1");
   #endif

   stbgl_initExtensions();

   #ifdef GL_DEBUG
   if (glDebugMessageCallbackARB) {
      glDebugMessageCallbackARB(gl_debug, NULL);

      enable_synchronous();
   }
   #endif

   SDL_GL_SetSwapInterval(1);

   render_init();
   mesh_init();
   world_init();

   initialized = 1;

   while (!quit) {
      SDL_Event e;
      while (SDL_PollEvent(&e))
         process_event(&e);

      loopmode(getTimestep(0.0166f/8), 1, 1);
   }

   return 0;
}