#include "../include/mgl/gl.h"
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>

typedef struct {
    void **func;
    const char *name;
} dlsym_assign;

static void* dlsym_print_fail(void *handle, const char *name, int required) {
    dlerror();
    void *sym = dlsym(handle, name);
    char *err_str = dlerror();

    if(!sym)
        fprintf(stderr, "mgl %s: dlsym(handle, \"%s\") failed, error: %s\n", required ? "error" : "warning", name, err_str ? err_str : "(null)");

    return sym;
}

int mgl_gl_load(mgl_gl *self) {
    /* Threaded gl optimization doesn't improve performance here, it just increases cpu usage, so force disable it if the user has enabled it */
    setenv("__GL_THREADED_OPTIMIZATIONS", "0", 1);

    const char *glx_path = "libGL.so.1";
    self->handle = dlopen(glx_path, RTLD_LAZY);
    if(!self->handle) {
        fprintf(stderr, "mgl error:dlopen(\"%s\", RTLD_LAZY) failed\n", glx_path);
        return -1;
    }

    const dlsym_assign required_dlsym[] = {
        { &self->glXCreateNewContext, "glXCreateNewContext" },
        { &self->glXMakeContextCurrent, "glXMakeContextCurrent" },
        { &self->glXDestroyContext, "glXDestroyContext" },
        { &self->glXSwapBuffers, "glXSwapBuffers" },
        { &self->glXChooseFBConfig, "glXChooseFBConfig" },
        { &self->glXGetVisualFromFBConfig, "glXGetVisualFromFBConfig" },

        { &self->glViewport, "glViewport" },
        { &self->glScissor, "glScissor" },
        { &self->glClearColor, "glClearColor" },
        { &self->glClear, "glClear" },
        { &self->glEnable, "glEnable" },
        { &self->glBlendFunc, "glBlendFunc" },
        { &self->glGenTextures, "glGenTextures" },
        { &self->glDeleteTextures, "glDeleteTextures" },
        { &self->glTexImage2D, "glTexImage2D" },
        { &self->glTexSubImage2D, "glTexSubImage2D" },
        { &self->glBindTexture, "glBindTexture" },
        { &self->glTexParameteri, "glTexParameteri" },
        { &self->glHint, "glHint" },
        { &self->glBegin, "glBegin" },
        { &self->glEnd, "glEnd" },
        { &self->glVertex3f, "glVertex3f" },
        { &self->glColor4ub, "glColor4ub" },
        { &self->glTexCoord2f, "glTexCoord2f" },
        { &self->glOrtho, "glOrtho" },
        { &self->glMatrixMode, "glMatrixMode" },
        { &self->glPushMatrix, "glPushMatrix" },
        { &self->glPopMatrix, "glPopMatrix" },
        { &self->glLoadIdentity, "glLoadIdentity" },
        { &self->glLoadMatrixf, "glLoadMatrixf" },
        { &self->glTranslatef, "glTranslatef" },
        { &self->glRotatef, "glRotatef" },
        { &self->glGenBuffers, "glGenBuffers" },
        { &self->glBindBuffer, "glBindBuffer" },
        { &self->glDeleteBuffers, "glDeleteBuffers" },
        { &self->glBufferData, "glBufferData" },
        { &self->glBufferSubData, "glBufferSubData" },
        { &self->glDrawArrays, "glDrawArrays" },
        { &self->glEnableClientState, "glEnableClientState" },
        { &self->glVertexPointer, "glVertexPointer" },
        { &self->glColorPointer, "glColorPointer" },
        { &self->glTexCoordPointer, "glTexCoordPointer" },
        { &self->glCompileShader, "glCompileShader" },
        { &self->glCreateProgram, "glCreateProgram" },
        { &self->glCreateShader, "glCreateShader" },
        { &self->glDeleteProgram, "glDeleteProgram" },
        { &self->glDeleteShader, "glDeleteShader" },
        { &self->glGetShaderiv, "glGetShaderiv" },
        { &self->glGetShaderInfoLog, "glGetShaderInfoLog" },
        { &self->glGetProgramiv, "glGetProgramiv" },
        { &self->glGetProgramInfoLog, "glGetProgramInfoLog" },
        { &self->glLinkProgram, "glLinkProgram" },
        { &self->glShaderSource, "glShaderSource" },
        { &self->glUseProgram, "glUseProgram" },
        { &self->glAttachShader, "glAttachShader" },
        { &self->glGetUniformLocation, "glGetUniformLocation" },
        { &self->glUniform1f, "glUniform1f" },
        { &self->glUniform2f, "glUniform2f" },
        { &self->glGetError, "glGetError" },
        { &self->glGetString, "glGetString" },
        { &self->glGetIntegerv, "glGetIntegerv" },
        { &self->glPixelStorei, "glPixelStorei" },

        { NULL, NULL }
    };

    for(int i = 0; required_dlsym[i].func; ++i) {
        *required_dlsym[i].func = dlsym_print_fail(self->handle, required_dlsym[i].name, 1);
        if(!*required_dlsym[i].func) {
            mgl_gl_unload(self);
            return -1;
        }
    }

    const dlsym_assign optional_dlsym[] = {
        { &self->glXSwapIntervalEXT, "glXSwapIntervalEXT" },
        { &self->glXSwapIntervalMESA, "glXGetSwapIntervalMESA" },
        { &self->glXSwapIntervalSGI, "glXSwapIntervalSGI" },

        { NULL, NULL }
    };

    for(int i = 0; optional_dlsym[i].func; ++i) {
        *optional_dlsym[i].func = dlsym_print_fail(self->handle, optional_dlsym[i].name, 0);
    }

    return 0;
}

void mgl_gl_unload(mgl_gl *self) {
    if(self->handle) {
        dlclose(self->handle);
        self->handle = NULL;
    }
}