#ifndef SRENDER_H
#define SRENDER_H

#ifdef __cplusplus
extern "C" {
#endif

#include <stdbool.h>
#include "vectorial/simd4x4f.h"

typedef struct srndr srndr;
typedef struct srview srview;
typedef struct srcmdbuf srcmdbuf;

typedef enum {
  SRndrCmdTypeFrame = 0,
  SRndrCmdTypeGrid,
  SRndrCmdTypeBox,
  SRndrCmdTypeLight,
  SRndrCmdTypeSphere
} SRndrCmdType;

typedef struct srcmd {
  simd4x4f mat;
  simd4f color;
  SRndrCmdType type;
} srcmd;

//
// Renderer
//
srndr* srndr_create();
void srndr_destroy(srndr* sr);

//
// View
//
srview* srview_create();
void srview_destroy(srview* sv);

void srview_set_proj(srview* sv, simd4x4f proj);
void srview_set_view(srview* sv, simd4x4f view);
void srview_set_size(srview* sv, int width, int height);
void srview_get_output_texture(srview* sv, GLuint* texture);

//
// Command Buffer and Commands
//
void srcmd_clear (srcmd *cmd);

srcmdbuf* srcmdbuf_create(unsigned int size_max);
void srcmdbuf_clear(srcmdbuf* cmdbuf);
bool srcmdbuf_add(srcmdbuf* cmdbuf, srcmd *cmd);
srcmd* srcmd_create(srcmdbuf* cmdbuf);

void srndr_render(srndr* srndr, srview* sview, srcmdbuf* scmdbuf);

//
// srender Implementation
//

#ifdef SRENDER_IMPLEMENTATION

#include "utils.h"

#include <string.h>
#include <assert.h>

typedef struct srndr {
} srndr;

typedef struct srview {
  GLuint width;
  GLuint height;

  GLuint mFrameBufferId;
  GLuint mColorTexture;
  GLuint mDepthTexture;

  simd4x4f proj;
  simd4x4f view;
} srview;

typedef struct srcmdbuf {
  int nbufsize;
  int ncmds;
  srcmd* cmds;
} srcmdbuf;

//
// Vertex Data
//
typedef union srvrtxdata {
  struct {
    float x, y, z, w;
    float nx, ny, nz;
    float s, t;
    GLubyte r, g, b, a;
  };
  struct {
    float pos[4];
    float n[4];
    float uv[2];
    GLubyte color[4];
  };
} srvrtxdata;

//
// Vertex Buffer Object for all debug objects (coord frame, grid, cube, ...)
//
const GLint DEBUG_VBO_SIZE = 1024;
GLuint gDebugShapesVBOId = 0;
GLuint gDebugShapesVAId = 0;

//
// Simple Mesh Data
//
typedef struct srmeshdata {
  int nvertices;
  int nindices;

  GLuint vao_id;
  GLuint vb_id;
  GLuint idb_id;

  GLuint count;
  GLenum mode;
} srmeshdata;

static srmeshdata gCoordFrameMesh = {0};
static srmeshdata gGridMesh = {0};

typedef struct srshader {
  const char* vert_fname;
  const char* frag_fname;

  GLuint program_id;
  GLuint vert_shader_id;
  GLuint frag_shader_id;
} srshader;

static srshader gDefaultShader =
    {"default_vert.glsl", "default_frag.glsl", 0, 0, 0};

bool srshader_compile(GLuint shader_id, const char* shader_src) {
  glShaderSource(shader_id, 1, &shader_src, 0);
  glCompileShader(shader_id);

  // Check Vertex Shader
  GLint result = GL_FALSE;
  int log_length = 0;
  glGetShaderiv(shader_id, GL_COMPILE_STATUS, &result);
  glGetShaderiv(shader_id, GL_INFO_LOG_LENGTH, &log_length);
  if (log_length > 0) {
    char* err_msg = calloc(log_length, sizeof(char));
    assert(err_msg);
    glGetShaderInfoLog(shader_id, log_length, NULL, err_msg);
    gLog("%s", err_msg);
    free(err_msg);

    return false;
  }

  return true;
}

bool srshader_load(
    srshader* shader,
    const char* vert_src,
    const char* frag_src) {
  shader->vert_shader_id = glCreateShader(GL_VERTEX_SHADER);
  if (!srshader_compile(shader->vert_shader_id, vert_src)) {
    gLog("Error compiling vertex shader!");
    return false;
  }

  shader->frag_shader_id = glCreateShader(GL_FRAGMENT_SHADER);
  if (!srshader_compile(shader->frag_shader_id, frag_src)) {
    gLog("Error compiling fragment shader!");
    return false;
  }

  shader->program_id = glCreateProgram();
  glAttachShader(shader->program_id, shader->vert_shader_id);
  glAttachShader(shader->program_id, shader->frag_shader_id);

  // Bind attribute locations
  glBindAttribLocation(shader->program_id, 0, "inCoord");
  glBindAttribLocation(shader->program_id, 1, "inNormal");
  glBindAttribLocation(shader->program_id, 2, "inUV");
  glBindAttribLocation(shader->program_id, 3, "inColor");

  glLinkProgram(shader->program_id);

  GLint result = GL_FALSE;
  int log_length = 0;
  glGetProgramiv(shader->program_id, GL_LINK_STATUS, &result);
  glGetProgramiv(shader->program_id, GL_INFO_LOG_LENGTH, &log_length);
  if (log_length > 0) {
    char* err_msg = calloc(log_length, sizeof(char));
    assert(err_msg);
    glGetProgramInfoLog(shader->program_id, log_length, NULL, err_msg);
    gLog("%s", err_msg);
    free(err_msg);
    gLog("Error linking shader program!");

    return false;
  }

  return true;
}

bool try_read_file(const char* dir, const char* filename, char** buf) {
  assert(*buf == NULL);

  int path_len = strlen(dir) + strlen(filename) + 1;
  char* path_buffer = calloc(path_len, sizeof(char));
  snprintf(path_buffer, path_len, "%s%s", dir, filename);
  long file_length = 0;

  FILE* file = NULL;
  file = fopen(path_buffer, "rb");
  if (file) {
    fseek(file, 0, SEEK_END);
    file_length = ftell(file);
    fseek(file, 0, SEEK_SET);
    *buf = calloc(file_length, sizeof(char));
    assert(*buf);
    fread(*buf, 1, file_length, file);
    fclose(file);

    return true;
  }

  return false;
}

void init_shaders() {
  static const char* shader_search_paths[] = {
      "./data/shaders/",
      "../data/shaders/",
      NULL};

  bool found = false;
  int search_index = 0;
  char* frag_buffer = NULL;
  char* vert_buffer = NULL;

  while (shader_search_paths[search_index] != NULL) {
    const char* dir = shader_search_paths[search_index];
    static char path_buf[1024];
    long length;

    if (vert_buffer == NULL) {
      try_read_file(dir, gDefaultShader.vert_fname, &vert_buffer);
    }
    if (frag_buffer == NULL) {
      try_read_file(dir, gDefaultShader.frag_fname, &frag_buffer);
    }

    if ((vert_buffer != NULL) && (frag_buffer != NULL)) {
      srshader_load(&gDefaultShader, vert_buffer, frag_buffer);

      free(vert_buffer);
      vert_buffer = NULL;
      free(frag_buffer);
      frag_buffer = NULL;
      break;
    }

    search_index++;
  }

  if (gDefaultShader.program_id == 0) {
    gLog("Error: could not load default shader!");
  }
}

void init_debug_meshes() {
  assert(gCoordFrameMesh.nvertices == 0);

  glGenVertexArrays(1, &gDebugShapesVAId);
  glBindVertexArray(gDebugShapesVAId);

  glGenBuffers(1, &gDebugShapesVBOId);
  glBindBuffer(GL_ARRAY_BUFFER, gDebugShapesVBOId);
  glBufferData(GL_ARRAY_BUFFER, sizeof(union srvrtxdata) * DEBUG_VBO_SIZE, NULL, GL_STATIC_DRAW);

  GLintptr dbg_vbuf_offset = 0;

  glEnableVertexAttribArray(0);
  glVertexAttribPointer(
      0,
      4,
      GL_FLOAT,
      GL_FALSE,
      (sizeof(srvrtxdata)),
      (void*)0);

  glEnableVertexAttribArray(1);
  glVertexAttribPointer(
      1,
      3,
      GL_FLOAT,
      GL_FALSE,
      (sizeof(srvrtxdata)),
      (void*)(sizeof(float) * 4));

  // Attribute 2: texture coordinates
  glEnableVertexAttribArray(2);
  glVertexAttribPointer(
      2,
      2,
      GL_FLOAT,
      GL_FALSE,
      (sizeof(srvrtxdata)),
      (void*)(sizeof(float) * 7));
  // Attribute 3: color
  glEnableVertexAttribArray(3);
  glVertexAttribPointer(
      3,
      4,
      GL_UNSIGNED_BYTE,
      GL_TRUE,
      (sizeof(srvrtxdata)),
      (void*)(sizeof(float) * 9));

  //
  // Coordinate Frame
  //
  gCoordFrameMesh.vao_id = gDebugShapesVAId;
  gCoordFrameMesh.vb_id = gDebugShapesVBOId;
  gCoordFrameMesh.nvertices = 6;

  srvrtxdata coord_frame_vertices[] = {
      {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 255, 0, 0, 255},
      {1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 255, 0, 0, 255},

      {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 255, 0, 255},
      {0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 255, 0, 255},

      {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 0, 255, 255},
      {0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 0, 255, 255}};
  GLuint coord_frame_indices[] = {0, 1, 2, 3, 4, 5};

  glBufferSubData(
      GL_ARRAY_BUFFER,
      dbg_vbuf_offset,
      sizeof(coord_frame_vertices),
      coord_frame_vertices);
  dbg_vbuf_offset = sizeof (coord_frame_vertices);

  glGenBuffers(1, &gCoordFrameMesh.idb_id);
  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gCoordFrameMesh.idb_id);
  glBufferData(
      GL_ELEMENT_ARRAY_BUFFER,
      sizeof(coord_frame_indices),
      coord_frame_indices,
      GL_STATIC_DRAW);

  gCoordFrameMesh.mode = GL_LINES;
  gCoordFrameMesh.count = 6;

  //
  // Coordinate Frame
  //
  gGridMesh.vao_id = gDebugShapesVAId;
  gGridMesh.vb_id = gDebugShapesVBOId;
  gGridMesh.nvertices = 44;

  srvrtxdata* grid_vertices = calloc(44, sizeof(srvrtxdata));
  srvrtxdata grid_def_vertex = {
      0.f, 0.f, 0.f, 1.f,
      0.f, 1.f, 0.f,
      0.f, 0.f,
      255, 255, 255, 255
  };
  // lines along parallel to x axis
  for (int i = 0; i <= 10; i++) {
    memcpy (&grid_vertices[2*i], &grid_def_vertex, sizeof(srvrtxdata));
    memcpy (&grid_vertices[2*i + 1], &grid_def_vertex, sizeof(srvrtxdata));
    grid_vertices[2 * i].pos[0] = -5.0f + i * 1.0f;
    grid_vertices[2 * i].pos[2] = 5.0f;
    grid_vertices[2 * i + 1].pos[0] = -5.0f + i * 1.0f;
    grid_vertices[2 * i + 1].pos[2] = -5.0f;
  }
  // lines parallel to z axis
  for (int i = 11; i <= 21; i++) {
    memcpy (&grid_vertices[2*i], &grid_def_vertex, sizeof(srvrtxdata));
    memcpy (&grid_vertices[2*i + 1], &grid_def_vertex, sizeof(srvrtxdata));
    grid_vertices[2 * i].pos[0] = -5.0f;
    grid_vertices[2 * i].pos[2] = -5.0f + (i - 11) * 1.0f;
    grid_vertices[2 * i + 1].pos[0] = 5.0f;
    grid_vertices[2 * i + 1].pos[2] = -5.0f + (i - 11) * 1.0f;
  }

  glBindBuffer(GL_ARRAY_BUFFER, gDebugShapesVBOId);
  glBufferSubData(
      GL_ARRAY_BUFFER,
      dbg_vbuf_offset,
      sizeof(srvrtxdata) * 44,
      grid_vertices);
  dbg_vbuf_offset += sizeof (srvrtxdata) * 44;

  free(grid_vertices);

  GLuint grid_indices[44];
  for (int i = 0; i < 22; i++) {
    grid_indices[2 * i] = 2*i + 6;
    grid_indices[2 * i + 1] = (2*i+1) + 6;
  }

  glGenBuffers(1, &gGridMesh.idb_id);
  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gGridMesh.idb_id);
  glBufferData(
      GL_ELEMENT_ARRAY_BUFFER,
      sizeof(grid_indices),
      grid_indices,
      GL_STATIC_DRAW);

  gGridMesh.mode = GL_LINES;
  gGridMesh.count = 44;

  glBindVertexArray(0);
};

//
// Renderer
//
srndr* srndr_create() {
  srndr* result = calloc(1, sizeof(srndr));

  init_shaders();
  init_debug_meshes();

  return result;
}

void srndr_destroy(srndr* sr) { free(sr); }

//
// View
//
void srview_get_output_texture(srview* sv, GLuint* texture) {
  *texture = sv->mColorTexture;
}

void srview_set_proj(srview* sv, simd4x4f proj) { sv->proj = proj; }

void srview_set_view(srview* sv, simd4x4f view) { sv->view = view; }

void srview_update_framebuffer(srview* sv) {
  glGenFramebuffers(1, &sv->mFrameBufferId);
  glBindFramebuffer(GL_FRAMEBUFFER, sv->mFrameBufferId);

  // Color Texture
  glGenTextures(1, &sv->mColorTexture);
  glBindTexture(GL_TEXTURE_2D, sv->mColorTexture);

  glTexImage2D(
      GL_TEXTURE_2D,
      0,
      GL_RGB,
      sv->width,
      sv->height,
      0,
      GL_RGB,
      GL_UNSIGNED_BYTE,
      0);

  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

  glFramebufferTexture2D(
      GL_FRAMEBUFFER,
      GL_COLOR_ATTACHMENT0,
      GL_TEXTURE_2D,
      sv->mColorTexture,
      0);

  // Depth Texture
  glGenTextures(1, &sv->mDepthTexture);
  glBindTexture(GL_TEXTURE_2D, sv->mDepthTexture);

  glTexImage2D(
      GL_TEXTURE_2D,
      0,
      GL_DEPTH_COMPONENT,
      sv->width,
      sv->height,
      0,
      GL_DEPTH_COMPONENT,
      GL_FLOAT,
      0);

  // Set parameters so that we can set a shadow2DSampler
  glTexParameteri(
      GL_TEXTURE_2D,
      GL_TEXTURE_COMPARE_MODE,
      GL_COMPARE_REF_TO_TEXTURE);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
  float border_color[] = {1.0f, 1.0f, 1.0f, 1.0f};
  glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, border_color);

  glFramebufferTexture2D(
      GL_FRAMEBUFFER,
      GL_DEPTH_ATTACHMENT,
      GL_TEXTURE_2D,
      sv->mDepthTexture,
      0);
}

void srview_cleanup_framebuffer(srview* sv) {
  if (glIsFramebuffer(sv->mFrameBufferId)) {
    glDeleteFramebuffers(1, &sv->mFrameBufferId);
  }

  if (sv->mColorTexture != -1) {
    glDeleteTextures(1, &sv->mColorTexture);
    sv->mColorTexture = -1;
  }

  if (sv->mDepthTexture != -1) {
    glDeleteTextures(1, &sv->mDepthTexture);
    sv->mDepthTexture = -1;
  }
}

void srview_set_size(srview* sv, int width, int height) {
  if (sv->width == width && sv->height == height) {
    return;
  }

  sv->width = width;
  sv->height = height;

  srview_cleanup_framebuffer(sv);
  srview_update_framebuffer(sv);
}

srview* srview_create() {
  srview* result = calloc(1, sizeof(srview));

  return result;
}

void srview_destroy(srview* sv) {
  srview_cleanup_framebuffer(sv);

  free(sv);
}

void srndr_run_frame_command(const srcmd* cmd) {
  glBindVertexArray(gCoordFrameMesh.vao_id);

  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gCoordFrameMesh.idb_id);
  glDrawElements(gCoordFrameMesh.mode, gCoordFrameMesh.count, GL_UNSIGNED_INT, (void*)0);

  glBindBuffer(GL_ARRAY_BUFFER, 0);
  glBindVertexArray(0);
}

void srndr_run_grid_command(const srcmd* cmd) {
  glBindVertexArray(gGridMesh.vao_id);

  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gGridMesh.idb_id);
  glDrawElements(gGridMesh.mode, gGridMesh.count, GL_UNSIGNED_INT, (void*)0);

  glBindBuffer(GL_ARRAY_BUFFER, 0);
  glBindVertexArray(0);
}

void srndr_render(srndr* srndr, srview* sview, srcmdbuf* scmdbuf) {
  glBindFramebuffer(GL_DRAW_FRAMEBUFFER, sview->mFrameBufferId);

  glViewport(0, 0, sview->width, sview->height);
  glClearColor(0.1f, 0.1f, 0.1f, 0.1f);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  glUseProgram(gDefaultShader.program_id);
  GLint view_mat_loc =
      glGetUniformLocation(gDefaultShader.program_id, "uViewMatrix");
  assert(view_mat_loc != -1);
  glUniformMatrix4fv(view_mat_loc, 1, GL_FALSE, &sview->view);

  GLint proj_mat_loc =
      glGetUniformLocation(gDefaultShader.program_id, "uProjectionMatrix");
  assert(proj_mat_loc != -1);
  glUniformMatrix4fv(proj_mat_loc, 1, GL_FALSE, &sview->proj);

  GLint model_mat_loc =
      glGetUniformLocation(gDefaultShader.program_id, "uModelMatrix");
  assert(model_mat_loc != -1);

  for (int i = 0; i < scmdbuf->ncmds; i++) {
    const srcmd* cmd = &scmdbuf->cmds[i];
    glUniformMatrix4fv(model_mat_loc, 1, GL_FALSE, &cmd->mat);

    switch (cmd->type) {
      case SRndrCmdTypeFrame:
        srndr_run_frame_command(cmd);
        break;
      case SRndrCmdTypeGrid:
        srndr_run_grid_command(cmd);
        break;
      default:
        gLog("Invalid command type %d at index %d", cmd->type, i);
        break;
    }
  }

  glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
}

//
// Render Commands
//
void srcmd_clear (srcmd *cmd) {
  cmd->color = simd4f_create(1.f, 1.f, 1.f, 1.f);
  cmd->type = SRndrCmdTypeFrame;
  simd4x4f_identity(&cmd->mat);
}

srcmdbuf* srcmdbuf_create(unsigned int size_max) {
  srcmdbuf* result = malloc(sizeof(srcmdbuf));
  result->nbufsize = size_max;
  result->ncmds = 0;
  result->cmds = calloc(sizeof(srcmd), size_max);

  return result;
}

void srcmdbuf_clear(srcmdbuf* cmdbuf) { cmdbuf->ncmds = 0; }

bool srcmdbuf_add(srcmdbuf* cmdbuf, srcmd *cmd) {
  srcmd *buf_cmd = srcmd_create(cmdbuf);

  if (!buf_cmd) {
    return false;
  }

  *buf_cmd = *cmd;
}

srcmd* srcmd_create(srcmdbuf* cmdbuf) {
  if (cmdbuf->ncmds == cmdbuf->nbufsize) {
    gLog("Warning: number of render commands maxed out!");
    return NULL;
  }
  return &(cmdbuf->cmds[cmdbuf->ncmds++]);
}

#endif // SRENDER_IMPLEMENTATION

#ifdef __cplusplus
}
#endif

#endif // SRENDER_H