drawing_gl 0.8.0

use crate::utils::shader::*;

pub struct Program {
    id: gl::types::GLuint,
}

impl Program {
    pub fn from_shaders(shaders: &[Shader]) -> Result<Program, String> {
        let program_id = unsafe { gl::CreateProgram() };

        for shader in shaders {
            unsafe {
                gl::AttachShader(program_id, shader.id());
            }
        }

        unsafe {
            gl::LinkProgram(program_id);
        }

        let mut success: gl::types::GLint = gl::FALSE as gl::types::GLint;
        unsafe {
            gl::GetProgramiv(program_id, gl::LINK_STATUS, &mut success);
        }

        if success != gl::TRUE as gl::types::GLint {
            let mut len: gl::types::GLint = 0;
            unsafe {
                gl::GetProgramiv(program_id, gl::INFO_LOG_LENGTH, &mut len);
            }

            let error = crate::utils::ffi_utils::create_whitespace_cstring_with_len(len as usize);

            unsafe {
                gl::GetProgramInfoLog(
                    program_id,
                    len,
                    std::ptr::null_mut(),
                    error.as_ptr() as *mut gl::types::GLchar,
                );
            }

            return Err(error.to_string_lossy().into_owned());
        }

        for shader in shaders {
            unsafe {
                gl::DetachShader(program_id, shader.id());
            }
        }

        Ok(Program { id: program_id })
    }

    pub fn id(&self) -> gl::types::GLuint {
        self.id
    }

    pub fn set_used(&self) {
        unsafe {
            gl::UseProgram(self.id);
        }
    }
}

impl Drop for Program {
    fn drop(&mut self) {
        unsafe {
            gl::DeleteProgram(self.id);
        }
    }
}