use crate::collision::Collider;
use crate::shader::Shader;
use nalgebra::{Matrix4, Vector3};
use gl;

/// Renders wireframe AABBs for debugging.
pub struct DebugRenderer {
    vao: u32,
    vbo: u32,
    shader: Shader,
}

impl DebugRenderer {
    /// Initialize the debug line VAO/VBO and load the debug shader.
    pub fn new() -> Self {
        // 12 edges × 2 verts × 3 coords = 72 floats
        let lines: [f32; 72] = [
            // bottom square
            0.0,0.0,0.0, 1.0,0.0,0.0,
            1.0,0.0,0.0, 1.0,0.0,1.0,
            1.0,0.0,1.0, 0.0,0.0,1.0,
            0.0,0.0,1.0, 0.0,0.0,0.0,
            // top square
            0.0,1.0,0.0, 1.0,1.0,0.0,
            1.0,1.0,0.0, 1.0,1.0,1.0,
            1.0,1.0,1.0, 0.0,1.0,1.0,
            0.0,1.0,1.0, 0.0,1.0,0.0,
            // verticals
            0.0,0.0,0.0, 0.0,1.0,0.0,
            1.0,0.0,0.0, 1.0,1.0,0.0,
            1.0,0.0,1.0, 1.0,1.0,1.0,
            0.0,0.0,1.0, 0.0,1.0,1.0,
        ];

        let mut vao = 0;
        let mut vbo = 0;
        unsafe {
            gl::GenVertexArrays(1, &mut vao);
            gl::GenBuffers(1, &mut vbo);
            gl::BindVertexArray(vao);
            gl::BindBuffer(gl::ARRAY_BUFFER, vbo);
            gl::BufferData(
                gl::ARRAY_BUFFER,
                (lines.len() * std::mem::size_of::<f32>()) as isize,
                lines.as_ptr() as *const _,
                gl::STATIC_DRAW,
            );
            gl::VertexAttribPointer(
                0,
                3,
                gl::FLOAT,
                gl::FALSE,
                3 * std::mem::size_of::<f32>() as i32,
                std::ptr::null(),
            );
            gl::EnableVertexAttribArray(0);
            gl::BindVertexArray(0);
        }

        // Load the simple debug shader
        let shader = Shader::new(
            "src/shaders/debug_vertex.glsl",
            "src/shaders/debug_fragment.glsl",
        );

        println!("DEBUG SHADER ID = {}", shader.id);

        DebugRenderer { vao, vbo, shader }
    }

    /// Draws the AABB collider in bright green lines, disabling depth test so it always shows.
    pub fn draw_collider(
        &self,
        view: &Matrix4<f32>,
        proj: &Matrix4<f32>,
        collider: &Collider,
    ) {
        // Compute model matrix to scale/translate unit cube into the collider AABB
        let scale = collider.max - collider.min;
        let translate = collider.min;
        let model = Matrix4::new_translation(&translate)
            * Matrix4::new_nonuniform_scaling(&scale);

        // Disable depth test so wireframe always draws on top
        unsafe { gl::Disable(gl::DEPTH_TEST); }

        // Use debug shader
        self.shader.use_program();
        self.shader.set_mat4("model", &model);
        self.shader.set_mat4("view", &view);
        self.shader.set_mat4("projection", &proj);
        self.shader.set_vec3("objectColor", &Vector3::new(0.5, 1.0, 0.5));

        // Render lines
        unsafe {
            gl::BindVertexArray(self.vao);
            gl::DrawArrays(gl::LINES, 0, 24);
            gl::BindVertexArray(0);
        }

        // Re-enable depth test for subsequent draws
        unsafe { gl::Enable(gl::DEPTH_TEST); }
    }
}