#include "../util/typedef.h"
#include "../util/string.h"
#include "../util/vector.h"
#include "../util/file.h"

#include <assert.h>

struct MODEL {

};

namespace OBJ {
  enum LINE_TYPES : U16 {
    comment = ( '#' | ( ' ' << 8 ) ),
    f       = ( 'f' | ( ' ' << 8 ) ),
    mtllib  = ( 'm' | ( 't' << 8 ) ),
    o       = ( 'o' | ( ' ' << 8 ) ),
    s       = ( 's' | ( ' ' << 8 ) ),
    v       = ( 'v' | ( ' ' << 8 ) ),
    vn      = ( 'v' | ( 'n' << 8 ) ),
    vt      = ( 'v' | ( 't' << 8 ) ),
    usemtl  = ( 'u' | ( 's' << 8 ) )
  };

  enum FACE_TYPES : U8 {
    V     = 0,
    VVT   = 1,
    VVN   = 2,
    VVTVN = 3
  };

  static inline U32 face_stride( FACE_TYPES t ) {
    switch( t ) {
    case FACE_TYPES::V:     return 1;
    case FACE_TYPES::VVT:   return 2;
    case FACE_TYPES::VVN:   return 2;
    case FACE_TYPES::VVTVN: return 3;
    }
    return 0;
  }

  constexpr U32 STR_LEN = 0x40;

  static inline char* skip_space( char* s ) {
    while( *s == ' ' || *s == '\t' ) ++s;
    return s;
  }

  static inline char* read_f32( char* s, F32* out ) {
    *out = strtof( s, &s );
    return s;
  }

  static inline char* read_u32( char* s, U32* out ) {
    *out = strtoul( s, &s, 10 );
    return s;
  }

  struct MTLDATA {
    STR name;
  };

  struct OBJDATA {
    LIST<VEC2> uvs;
    LIST<VEC3> normals;
    LIST<VEC3> vertices;

    LIST<MTLDATA> mtllib;

    struct UseMtl {
      LIST<U32> indices;
      LIST<STR> data;
    } usemtl;

    struct Indices {
      LIST<U32> data;
      LIST<U32> counts;
      LIST<FACE_TYPES> types;
    } indices;
  };

  inline OBJDATA obj_from_file( const char* path, const char* name ) {
    char* f_obj = nullptr;
    STR obj_path( path );
    U64 obj_size = 0;
    obj_path += name;
    obj_path += ".obj";

    f_obj = (char*)file_read( obj_path.data, &obj_size );
    if( !f_obj ) {
      dlog( "obj_from_file() : failed to read obj file %s\n", obj_path.data );
      return {};
    }
    dlog( "___modelfile___\n%s\n", f_obj );

    OBJDATA obj;
    for( U64 i = 0; i < obj_size - 1 && f_obj[i]; ++i ) {
      if( f_obj[i] == (I32)'#' ) {
        while( f_obj[i] && f_obj[i] != '\n' ) ++i;
        continue;
      }

      I32 c0 = f_obj[i];
      U16 c1 = f_obj[i + 1];
      I32 first_two = c0 | c1 << 8;

      switch( first_two ) {
      case LINE_TYPES::f: {
        FACE_TYPES type = FACE_TYPES::V;
        char* s = f_obj + i + 2;
        bool type_set = 0;
        U32 count = 0;

        s = skip_space( s );

        while( *s && *s != '\n' ) {
          bool has_vt = 0, has_vn = 0;
          U32 v = 0, vt = 0, vn = 0;
          s = read_u32( s, &v );
          obj.indices.data.push( --v );

          if( *s == '/' ) {
            ++s;

            if( *s != '/' ) {
              s = read_u32( s, &vt );
              obj.indices.data.push( --vt );
              has_vt = 1;
            }

            if( *s == '/' ) {
              s = read_u32( ++s, &vn );
              obj.indices.data.push( --vn );
              has_vn = 1;
            }
          }

          if( !type_set ) {
            if( has_vt && has_vn )
              type = FACE_TYPES::VVTVN;
            else if( has_vt )
              type = FACE_TYPES::VVT;
            else if( has_vn )
              type = FACE_TYPES::VVN;
            else
              type = FACE_TYPES::V;
            type_set = 1;
          }

          ++count;

          while( *s && *s != ' ' && *s != '\n' )
            ++s;
          s = skip_space( s );
        }
        obj.indices.counts.push( count );
        obj.indices.types.push( type );
      } break;
      case LINE_TYPES::v:
      case LINE_TYPES::vn: {
        bool is_v = first_two == LINE_TYPES::v;
        U32 start = i + ( is_v ? 2 : 3 );
        char* s = f_obj + start;
        VEC3 temp{};
        s = skip_space( s );
        s = read_f32( s, &temp.x );
        s = skip_space( s );
        s = read_f32( s, &temp.y );
        s = skip_space( s );
        s = read_f32( s, &temp.z );
        if( is_v )
          obj.vertices.push( temp );
        else
          obj.normals.push( temp );
      } break;
      case LINE_TYPES::vt: {
        char* s = f_obj + i + 3;
        VEC2 temp{};
        s = skip_space( s );
        s = read_f32( s, &temp.x );
        s = skip_space( s );
        s = read_f32( s, &temp.y );
        obj.uvs.push( temp );
      } break;
      case LINE_TYPES::mtllib:
      case LINE_TYPES::usemtl: {
        bool is_mtllib = first_two == LINE_TYPES::mtllib;
        char* start = f_obj + i + 7;
        char* end = start;
        while( *end && *end != '\n' ) ++end;
        U32 len = end - start;
        STR temp;
        temp.reserve( len + 1 );
        memcpy( temp, start, len );
        temp.data[len] = 0;
        if( !is_mtllib ) {
          obj.usemtl.data.push( temp );
          obj.usemtl.indices.push( obj.indices.data.size );
        }
        else {
          U64 mtl_size = 0;
          STR mtl_path( path );
          mtl_path += temp.data;
          char* f_mtl = (char*)file_read( mtl_path.data, &mtl_size );
          if( !f_mtl ) {
            dlog( "obj_from_file() : failed to read mtl file %s\n", mtl_path.data );
            return {};
          }
          dlog( "___mtlfile___\n%s\n", f_mtl );

          // TODO: finish mtl parsing here into obj.mtllib

          obj.mtllib.push({ temp });
          free( (void*)f_mtl );
        }
      } break;
      case LINE_TYPES::comment:
      case LINE_TYPES::o:
      case LINE_TYPES::s: break;
      default: dlog( "unhandled char combo %c%c\n", c0, c1 ); break;
      }

      while( f_obj[i] && f_obj[i] != '\n' ) ++i;
    }
    free( (void*)f_obj );
    return obj;
  }

  inline MODEL obj_to_model( OBJDATA obj ) {
    MODEL model;

    return model;
  }
};

inline MODEL model_from_obj( const I8* path, const I8* name ) {
  OBJ::OBJDATA obj = OBJ::obj_from_file( path, name );
  return OBJ::obj_to_model( obj );
}