/* Copyright (c) 2025 Quinn
 * Licensed under the MIT Licence. See LICENSE for details */
#include "shader.h"

#include <stddef.h>
#include <stdint.h>
#include <stdio.h>

#include "../util/error.h"


/* NOTE: we are currently just sucking up the memory costs for ease. We can either include the
 * source files themselves. Or use compression, where I'd prefer the latter for ease of
 * installation. */
extern const char sh_vert_glsl[];
extern const char sh_frag_glsl[];
extern const char sh_geom_glsl[];
extern const uint sh_vert_glsl_len;
extern const uint sh_frag_glsl_len;
extern const uint sh_geom_glsl_len;

/* Compiles a shader of `type` from `src` with `len` bytes.
 * Returns the integer for the shader. */
static GLuint shader_compile(GLenum type, const char *src, usize len)
{
	int    ilen   = len;
	GLuint shader = glCreateShader(type);
	glShaderSource(shader, 1, &src, &ilen);
	glCompileShader(shader);

	// repurposing ilen for the max length of the shader log
	glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &ilen);
	if (ilen > 0) {
		char log[ilen];
		glGetShaderInfoLog(shader, ilen, &ilen, log);
		log[ilen - 1] = '\0'; // terminate the string one character sooner since the log
				      // includes a newline
		error("error whilst compiling shader type '0x%X': '%s'", type, log);
	}

	return shader;
}

int shader_init(GLuint pipe)
{
	GLuint vs = shader_compile(GL_VERTEX_SHADER, sh_vert_glsl, sh_vert_glsl_len);
	GLuint fs = shader_compile(GL_FRAGMENT_SHADER, sh_frag_glsl, sh_frag_glsl_len);
	GLuint gs = shader_compile(GL_GEOMETRY_SHADER, sh_geom_glsl, sh_geom_glsl_len);

	glAttachShader(pipe, vs);
	glAttachShader(pipe, fs);
	glAttachShader(pipe, gs);

	// mark shaders off for deletion
	glDeleteShader(vs);
	glDeleteShader(fs);
	glDeleteShader(gs);
	return 1;
}