using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using GLenum     = System.UInt32;
using GLboolean  = System.Byte  ;
using GLbitfield = System.UInt32;
using GLvoid     = System.Void  ;
using GLbyte     = System.SByte ;
using GLshort    = System.Int16 ;
using GLint      = System.Int32 ;
using GLubyte    = System.Byte  ;
using GLushort   = System.UInt16;
using GLuint     = System.UInt32;
using GLsizei    = System.Int32 ;
using GLfloat    = System.Single;
using GLclampf   = System.Single;
using GLdouble   = System.Double;
using GLclampd   = System.Double;
using GLchar     = System.SByte ;

namespace PoroCYon.FNAGLSL {
	public static unsafe partial class GL {
		static void InitProcs() {
			_GetError      = GetProcAddress<GetError_T>("GetError");
			_CreateProgram = GetProcAddress<CreateProgram_T>("CreateProgram");
			_CreateShader  = GetProcAddress<CreateShader_T>("CreateShader");
			_ShaderSource  = GetProcAddress<ShaderSource_T>("ShaderSource");
			_CompileShader = GetProcAddress<CompileShader_T>("CompileShader");
			_GetShaderiv   = GetProcAddress<GetShaderiv_T>("GetShaderiv");
			_GetShaderInfoLog = GetProcAddress<GetShaderInfoLog_T>("GetShaderInfoLog");
			_AttachShader  = GetProcAddress<AttachShader_T>("AttachShader");
			_LinkProgram   = GetProcAddress<LinkProgram_T>("LinkProgram");
			_GetProgramiv  = GetProcAddress<GetProgramiv_T>("GetProgramiv");
			_GetProgramInfoLog = GetProcAddress<GetProgramInfoLog_T>("GetProgramInfoLog");
			_DeleteShader  = GetProcAddress<DeleteShader_T>("DeleteShader");
			_DeleteProgram = GetProcAddress<DeleteProgram_T>("DeleteProgram");
			_UseProgram    = GetProcAddress<UseProgram_T>("UseProgram");
			_GetIntegerv   = GetProcAddress<GetIntegerv_T>("GetIntegerv");
			_GetActiveAttrib    = GetProcAddress<GetActiveAttrib_T>("GetActiveAttrib");
			_GetAttribLocation  = GetProcAddress<GetAttribLocation_T>("GetAttribLocation");
			_GetUniformIndices  = GetProcAddress<GetUniformIndices_T>("GetUniformIndices");
			_GetUniformLocation = GetProcAddress<GetUniformLocation_T>("GetUniformLocation");
			_GetActiveUniformName = GetProcAddress<GetActiveUniformName_T>("GetActiveUniformName");
			_GetActiveUniformsiv  = GetProcAddress<GetActiveUniformsiv_T>("GetActiveUniformsiv");
			_GetActiveUniform     = GetProcAddress<GetActiveUniform_T>("GetActiveUniform");
		}
		static void DeinitProcs() {
			_GetError      = null;
			_CreateProgram = null;
			_CreateShader  = null;
			_ShaderSource  = null;
			_CompileShader = null;
			_GetShaderiv   = null;
			_GetShaderInfoLog = null;
			_AttachShader  = null;
			_LinkProgram   = null;
			_GetProgramiv  = null;
			_GetProgramInfoLog = null;
			_DeleteShader  = null;
			_DeleteProgram = null;
			_UseProgram    = null;
			_GetIntegerv   = null;
			_GetActiveAttrib    = null;
			_GetAttribLocation  = null;
			_GetUniformIndices  = null;
			_GetUniformLocation = null;
			_GetActiveUniformName = null;
			_GetActiveUniformsiv  = null;
			_GetActiveUniform     = null;
		}

		delegate GLenum GetError_T();
		static GetError_T _GetError;
		public static GLError GetError() => (GLError)_GetError();

		delegate GLuint CreateProgram_T();
		static CreateProgram_T _CreateProgram;
		public static GLuint CreateProgram() => _CreateProgram();

		delegate GLuint CreateShader_T(GLenum shtyp);
		static CreateShader_T _CreateShader;
		public static GLuint CreateShader(GLSLPurpose shtyp)
			=> _CreateShader((GLenum)shtyp);

		delegate void ShaderSource_T(GLuint sh, GLsizei count,
				GLchar** str, GLint* len);
		static ShaderSource_T _ShaderSource;
		public static void ShaderSource(GLuint sh, GLsizei count,
				GLchar** str, GLint* len) {
			_ShaderSource(sh, count, str, len);
		}

		delegate void CompileShader_T(GLuint sh);
		static CompileShader_T _CompileShader;
		public static void CompileShader(GLuint sh) { _CompileShader(sh); }

		delegate void GetShaderiv_T(GLuint sh, GLenum pname, GLint* parm);
		static GetShaderiv_T _GetShaderiv;
		public static GLint GetShaderiv(GLuint sh, GLenum pname) {
			GLint* parm = stackalloc GLint[1];
			*parm = 0;
			_GetShaderiv(sh, pname, parm);
			return *parm;
		}

		delegate void GetShaderInfoLog_T(GLuint sh, GLsizei maxl, GLsizei* len,
				GLchar* infolog);
		static GetShaderInfoLog_T _GetShaderInfoLog;
		public static string GetShaderInfoLog(GLuint sh, GLsizei maxl) {
			GLchar[] logbuf = new GLchar[maxl];
			GLsizei len = 0;
			fixed (GLchar* logp = logbuf) {
				_GetShaderInfoLog(sh, maxl, &len, logp);
				return new String(logp, 0, len, Encoding.UTF8);
			}
		}

		delegate void AttachShader_T(GLuint pr, GLuint sh);
		static AttachShader_T _AttachShader;
		public static void AttachShader(GLuint prgm, GLuint sh) {
			_AttachShader(prgm, sh);
		}

		delegate void LinkProgram_T(GLuint pr);
		static LinkProgram_T _LinkProgram;
		public static void LinkProgram(GLuint prgm) { _LinkProgram(prgm); }

		delegate void GetProgramiv_T(GLuint pr, GLuint pnam, GLint* parm);
		static GetProgramiv_T _GetProgramiv;
		// FIXME: won't work with GL_COMPUTE_WORK_GROUP_SIZE
		public static GLint GetProgramiv(GLuint prgm, GLenum pname) {
			GLint* parm = stackalloc GLint[3];
			parm[2] = parm[1] = parm[0] = 0;
			_GetProgramiv(prgm, pname, parm);
			return parm[0];
		}

		delegate void GetProgramInfoLog_T(GLuint pr, GLsizei maxl,
				GLsizei* len, GLchar* infolog);
		static GetProgramInfoLog_T _GetProgramInfoLog;
		public static string GetProgramInfoLog(GLuint prgm, GLsizei maxl) {
			GLchar[] logbuf = new GLchar[maxl];
			GLsizei len = 0;
			fixed (GLchar* logp = logbuf) {
				_GetProgramInfoLog(prgm, maxl, &len, logp);
				return new String(logp, 0, len, Encoding.UTF8);
			}
		}

		delegate void DeleteShader_T(GLuint sh);
		static DeleteShader_T _DeleteShader;
		public static void DeleteShader(GLuint sh) { _DeleteShader(sh); }

		delegate void DeleteProgram_T(GLuint pr);
		static DeleteProgram_T _DeleteProgram;
		public static void DeleteProgram(GLuint prgm) { _DeleteProgram(prgm); }

		delegate void UseProgram_T(GLuint pr);
		static UseProgram_T _UseProgram;
		public static void UseProgram(GLuint prgm) { _UseProgram(prgm); }

		delegate void GetIntegerv_T(GLenum n, GLint* parm);
		static GetIntegerv_T _GetIntegerv;
		public static GLint GetIntegerv(GLenum name) {
			GLint* parm = stackalloc GLint[4]; // let's hope 4 is good enough
			parm[3] = parm[2] = parm[1] = parm[0] = 0;
			_GetIntegerv(name, parm);
			return parm[0];
		}

		// TODO:

		const int NAMEBUF_MAX_LEN = 64;

		delegate void GetActiveAttrib_T(GLuint prgm, GLuint idx, GLsizei bufSize,
			GLsizei* len, GLint* size, GLenum* type, GLchar* name);
		static GetActiveAttrib_T _GetActiveAttrib;
		public static void GetActiveAttrib(GLuint prgm, GLuint index,
				out GLint size, out GLSLType type, out string name) {
			GLchar* namebuf = stackalloc GLchar[NAMEBUF_MAX_LEN];
			GLsizei namelen = 0;

			size = 0;
			GLenum _typ = 0;
			fixed (GLint* psize = &size) {
				_GetActiveAttrib(prgm, index,
					(GLsizei)(NAMEBUF_MAX_LEN*sizeof(GLchar)),
					&namelen, psize, &_typ, namebuf);
			}
			name = new String(namebuf, 0, namelen, Encoding.UTF8);
			type = (GLSLType)_typ;
		}

		delegate GLint GetAttribLocation_T(GLuint prgm, GLchar* name);
		static GetAttribLocation_T _GetAttribLocation;
		public static GLint GetAttribLocation(GLuint prgm, string name) {
			byte[] blargh = Encoding.UTF8.GetBytes(name);

			fixed (byte* bb = blargh) {
				return _GetAttribLocation(prgm, (GLchar*)bb);
			}
		}

		delegate void GetUniformIndices_T(GLuint prgm, GLsizei unifCnt,
				GLchar** unifNames, GLuint* unifIdxs);
		static GetUniformIndices_T _GetUniformIndices;
		public static void GetUniformIndices(GLuint prgm,
				string[] names, GLuint[] idxs) {
			if (names == null) throw new ArgumentNullException("names");
			if (idxs  == null) throw new ArgumentNullException("idxs" );
			if (names.Length != idxs.Length) throw new ArgumentException("#names != #idxs");

			// marshal the string array...

			// convert all the string to utf8
			int totallen = 0;
			byte[][] bytes = new byte[names.Length][];
			for (int i = 0; i < names.Length; ++i) {
				bytes[i] = Encoding.UTF8.GetBytes(names[i]);
				totallen += bytes[i].Length;
			}
			// rearrange pointer crap to that glGetUniformIndices can read it
			byte[] bytesbytes = new byte[totallen];
			GLchar*[] ptrs = new GLchar*[names.Length];
			fixed (byte* bbp = bytesbytes) {
				int totalidx = 0;
				for (int i = 0; i < names.Length; ++i) {
					Array.Copy(bytes[i], 0, bytesbytes, totalidx, bytes[i].Length);
					ptrs[i] = (GLchar*)&bbp[totalidx];
					totalidx += bytes[i].Length;
				}

				// now we can actually call the function
				fixed (GLchar** strp = ptrs) {
					fixed (GLuint* idxp = idxs) {
						_GetUniformIndices(prgm, names.Length, strp, idxp);
					}
				}
			}
		}

		delegate void GetActiveUniformName_T(GLuint prgm, GLuint unifIdx,
				GLsizei bufSize, GLsizei* length, GLchar* unifName);
		static GetActiveUniformName_T _GetActiveUniformName;
		public static string GetActiveUniformName(GLuint prgm, GLuint unifIdx) {
			GLchar* namebuf = stackalloc GLchar[NAMEBUF_MAX_LEN];
			GLsizei namelen = 0;

			_GetActiveUniformName(prgm, unifIdx,
				(GLsizei)(NAMEBUF_MAX_LEN*sizeof(GLchar)),
				&namelen, namebuf);
			return new String(namebuf, 0, namelen, Encoding.UTF8);
		}

		delegate void GetActiveUniformsiv_T(GLuint prgm, GLsizei unifCnt,
				GLuint* unifIdxs, GLenum pname, GLint* parms);
		static GetActiveUniformsiv_T _GetActiveUniformsiv;
		public static void GetActiveUniformsiv(GLuint prgm,
				GLuint[] unifIdxs, GLenum pname, GLint[] parms) {
			if (unifIdxs == null) throw new ArgumentNullException("unifIdxs");
			if (parms    == null) throw new ArgumentNullException("parms"   );
			if (unifIdxs.Length != parms.Length) throw new ArgumentException("#unifIdxs != #parms");

			fixed (GLuint* idxs = unifIdxs) {
				fixed (GLint* ps = parms) {
					_GetActiveUniformsiv(prgm, parms.Length, idxs, pname, ps);
				}
			}
		}

		delegate void GetActiveUniform_T(GLuint prgm, GLuint idx, GLsizei bufSize,
				GLsizei* length, GLint* size, GLenum* type, GLchar* name);
		static GetActiveUniform_T _GetActiveUniform;
		public static void GetActiveUniform(GLuint prgm, GLuint idx,
				out GLint size, out GLSLType type, out string name) {
			GLchar* namebuf = stackalloc GLchar[NAMEBUF_MAX_LEN];
			GLsizei namelen = 0;

			size = 0;
			GLenum _typ = 0;
			fixed (GLint* psize = &size) {
				_GetActiveUniform(prgm, idx,
					(GLsizei)(NAMEBUF_MAX_LEN*sizeof(GLchar)),
					&namelen, psize, &_typ, namebuf);
			}
			name = new String(namebuf, 0, namelen, Encoding.UTF8);
			type = (GLSLType)_typ;
		}

		delegate GLint GetUniformLocation_T(GLuint prgm, GLchar* name);
		static GetUniformLocation_T _GetUniformLocation;
		public static GLint GetUniformLocation(GLuint prgm, string name) {
			if (name == null) throw new ArgumentNullException("name");

			byte[] bytes = Encoding.UTF8.GetBytes(name);
			fixed (byte* bp = bytes) {
				return _GetUniformLocation(prgm, (GLchar*)bp);
			}
		}

		// TODO: glUniform functions
	}
}