use std::{
	fs::File,
	io::Write,
};

fn main () {
	let vertexes = [
		[-1.0, -1.0, -1.0],
		[ 1.0, -1.0, -1.0],
		[ 1.0,  1.0, -1.0],
		[-1.0,  1.0, -1.0],
		
		[-1.0, -1.0,  1.0],
		[ 1.0, -1.0,  1.0],
		[ 1.0,  1.0,  1.0],
		[-1.0,  1.0,  1.0],
	];
	
	let triangles = [
		[0, 2, 1],
		[0, 3, 2],
		
		[0, 5, 1],
		[1, 6, 2],
		[2, 7, 3],
		[3, 4, 0],
		
		[0, 4, 5],
		[1, 5, 6],
		[2, 6, 7],
		[3, 7, 4],
		
		[4, 6, 5],
		[4, 7, 6],
	];
	
	let num_vertexes = u32::try_from (vertexes.len ()).unwrap ();
	let num_triangles = u32::try_from (triangles.len ()).unwrap ();
	
	let mut texts = Vec::default ();
	
	let mesh = iqm::Mesh {
		name: u32::try_from (texts.len ()).unwrap (),
		material: 0,
		first_vertex: 0,
		num_vertexes,
		first_triangle: 0,
		num_triangles,
	};
	texts.push ("Cube");
	
	let meshes = vec! [
		mesh,
	];
	
	let num_text: usize = texts.iter ()
	.map (|s| s.len () + 1)
	.sum ();
	let num_text = u32::try_from (num_text).unwrap ();
	
	let num_meshes = u32::try_from (meshes.len ()).unwrap ();
	let num_vertexarrays = 1u32;
	
	let header_len = 124u32;
	let ofs_meshes = header_len;
	let ofs_vertexarrays = ofs_meshes + num_meshes * 6 * 4;
	let ofs_triangles = ofs_vertexarrays + num_vertexarrays * 5 * 4 + num_vertexes * 3 * 4;
	let ofs_text = ofs_triangles + num_triangles * 3 * 4;
	
	let filesize = ofs_text + num_text;
	
	let mut f = File::create ("cube.iqm").unwrap ();
	
	f.write_all (b"INTERQUAKEMODEL\0").unwrap ();
	
	f.write_all (&(2u32.to_le_bytes ())).unwrap ();
	
	// filesize
	f.write_all (&(filesize.to_le_bytes ())).unwrap ();
	
	// flags
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	
	// num_text, ofs_text
	f.write_all (&(num_text.to_le_bytes ())).unwrap ();
	f.write_all (&(ofs_text.to_le_bytes ())).unwrap ();
	
	// num_meshes, ofs_meshes
	f.write_all (&(num_meshes.to_le_bytes ())).unwrap ();
	f.write_all (&(ofs_meshes.to_le_bytes ())).unwrap ();
	
	// num_vertexarrays, num_vertexes, ofs_vertexarrays
	f.write_all (&(num_vertexarrays.to_le_bytes ())).unwrap ();
	f.write_all (&(num_vertexes.to_le_bytes ())).unwrap ();
	f.write_all (&(ofs_vertexarrays.to_le_bytes ())).unwrap ();
	
	// num_triangles, ofs_triangles, ofs_adjacency
	f.write_all (&(num_triangles.to_le_bytes ())).unwrap ();
	f.write_all (&(ofs_triangles.to_le_bytes ())).unwrap ();
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	
	// num_joints, ofs_joints
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	
	// num_poses, ofs_poses
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	
	// num_anims, ofs_anims
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	
	// num_frames, num_framechannels, ofs_frames, ofs_bounds
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	
	// num_comment, ofs_comment
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	
	// num_extensions, ofs_extensions
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	
	// Meshes
	
	for mesh in meshes {
		f.write_all (&(mesh.name.to_le_bytes ())).unwrap ();
		f.write_all (&(mesh.material.to_le_bytes ())).unwrap ();
		f.write_all (&(mesh.first_vertex.to_le_bytes ())).unwrap ();
		f.write_all (&(mesh.num_vertexes.to_le_bytes ())).unwrap ();
		f.write_all (&(mesh.first_triangle.to_le_bytes ())).unwrap ();
		f.write_all (&(mesh.num_triangles.to_le_bytes ())).unwrap ();
	}
	
	// Vertex arrays
	
	// type
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	
	// flags
	f.write_all (&(0u32.to_le_bytes ())).unwrap ();
	
	// format
	f.write_all (&(7u32.to_le_bytes ())).unwrap ();
	
	// size
	f.write_all (&(3u32.to_le_bytes ())).unwrap ();
	
	// offset
	f.write_all (&(0xA8u32.to_le_bytes ())).unwrap ();
	
	// Vertexes
	
	for t in vertexes {
		for x in t {
			f.write_all (&(f32::to_le_bytes (x))).unwrap ();
		}
	}
	
	// Triangles
	
	for t in triangles {
		for x in t {
			f.write_all (&(u32::to_le_bytes (x))).unwrap ();
		}
	}
	
	// Text
	for s in texts {
		f.write_all (s.as_bytes ()).unwrap ();
		f.write_all (b"\0").unwrap ();
	}
}

/// IQM structures as written to disk

mod iqm {
	pub struct Mesh {
		pub name: u32,
		pub material: u32,
		pub first_vertex: u32,
		pub num_vertexes: u32,
		pub first_triangle: u32,
		pub num_triangles: u32,
	}
	
	struct VertexArray {
		r#type: u32,
		flags: u32,
		format: u32,
		size: u32,
		offset: u32,
	}
	
	struct Triangle {
		vertex: [u32; 3],
	}
	
	struct Vertex {
		position: [f32; 3],
	}
}