/**********************************************************************
*
* Sokol 3d cube multishader demo
*
* Copyright (c) 2021 Dario Deledda. All rights reserved.
* Use of this source code is governed by an MIT license
* that can be found in the LICENSE file.
*
* HOW TO COMPILE SHADERS:
* Run `v shader .` in this directory to compile the shaders.
* For more info and help with shader compilation see `docs.md` and `v help shader`.
*
* TODO:
* - frame counter
**********************************************************************/
import gg
import gg.m4
import gx
// import math
import sokol.sapp
import sokol.gfx
import sokol.sgl
import time

// GLSL Include and functions
#flag -I @VMODROOT/.
#include "rt_glsl_march.h" # Should be generated with `v shader .` (see the instructions at the top of this file)
#include "rt_glsl_puppy.h" # Should be generated with `v shader .` (see the instructions at the top of this file)

fn C.rt_march_shader_desc(gfx.Backend) &gfx.ShaderDesc
fn C.rt_puppy_shader_desc(gfx.Backend) &gfx.ShaderDesc

const (
	win_width  = 800
	win_height = 800
	bg_color   = gx.white
)

struct App {
mut:
	gg          &gg.Context = unsafe { nil }
	texture     gfx.Image
	init_flag   bool
	frame_count int
	mouse_x     int = -1
	mouse_y     int = -1
	mouse_down  bool
	// glsl
	cube_pip_glsl gfx.Pipeline
	cube_bind     gfx.Bindings
	pipe          map[string]gfx.Pipeline
	bind          map[string]gfx.Bindings
	// time
	ticks i64
}

/******************************************************************************
* Texture functions
******************************************************************************/
fn create_texture(w int, h int, buf byteptr) gfx.Image {
	sz := w * h * 4
	mut img_desc := gfx.ImageDesc{
		width: w
		height: h
		num_mipmaps: 0
		min_filter: .linear
		mag_filter: .linear
		// usage: .dynamic
		wrap_u: .clamp_to_edge
		wrap_v: .clamp_to_edge
		label: &u8(0)
		d3d11_texture: 0
	}
	// comment if .dynamic is enabled
	img_desc.data.subimage[0][0] = gfx.Range{
		ptr: buf
		size: usize(sz)
	}

	sg_img := gfx.make_image(&img_desc)
	return sg_img
}

fn destroy_texture(sg_img gfx.Image) {
	gfx.destroy_image(sg_img)
}

// Use only if usage: .dynamic is enabled
fn update_text_texture(sg_img gfx.Image, w int, h int, buf byteptr) {
	sz := w * h * 4
	mut tmp_sbc := gfx.ImageData{}
	tmp_sbc.subimage[0][0] = gfx.Range{
		ptr: buf
		size: usize(sz)
	}
	gfx.update_image(sg_img, &tmp_sbc)
}

/******************************************************************************
* Draw functions
******************************************************************************
Cube vertex buffer with packed vertex formats for color and texture coords.
		Note that a vertex format which must be portable across all
		backends must only use the normalized integer formats
		(BYTE4N, UBYTE4N, SHORT2N, SHORT4N), which can be converted
		to floating point formats in the vertex shader inputs.
		The reason is that D3D11 cannot convert from non-normalized
		formats to floating point inputs (only to integer inputs),
		and WebGL2 / GLES2 don't support integer vertex shader inputs.
*/
struct Vertex_t {
	x     f32
	y     f32
	z     f32
	color u32
	// u u16   // for compatibility with D3D11
	// v u16   // for compatibility with D3D11
	u f32
	v f32
}

// march shader init
fn init_cube_glsl_m(mut app App) {
	// cube vertex buffer
	// d := u16(32767)     // for compatibility with D3D11, 32767 stand for 1
	d := f32(1.0)
	c := u32(0xFFFFFF_FF) // color RGBA8
	// vfmt off
	vertices := [
		// Face 0
		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
		Vertex_t{ 1.0, -1.0, -1.0, c,  d, 0},
		Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
		Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
		// Face 1
		Vertex_t{-1.0, -1.0,  1.0, c,  0, 0},
		Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
		Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
		// Face 2
		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
		Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
		Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
		Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
		// Face 3
		Vertex_t{ 1.0, -1.0, -1.0, c,  0, 0},
		Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
		Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
		// Face 4
		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
		Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
		Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
		Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
		// Face 5
		Vertex_t{-1.0,  1.0, -1.0, c,  0, 0},
		Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
		Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
	]
	// vfmt on

	mut vert_buffer_desc := gfx.BufferDesc{
		label: c'cube-vertices'
	}
	unsafe { vmemset(&vert_buffer_desc, 0, int(sizeof(vert_buffer_desc))) }
	vert_buffer_desc.size = usize(vertices.len * int(sizeof(Vertex_t)))
	vert_buffer_desc.data = gfx.Range{
		ptr: vertices.data
		size: usize(vertices.len * int(sizeof(Vertex_t)))
	}
	vert_buffer_desc.@type = .vertexbuffer
	vbuf := gfx.make_buffer(&vert_buffer_desc)

	// create an index buffer for the cube
	// vfmt off
	indices := [
		u16(0), 1,  2,   0,  2,  3,
		    6 , 5,  4,   7,  6,  4,
		    8 , 9, 10,   8, 10, 11,
/*
		u16(14), 13, 12,    15, 14, 12,
		     16, 17, 18,    16, 18, 19,
		     22, 21, 20,    23, 22, 20,
*/
	]
	// vfmt on

	mut index_buffer_desc := gfx.BufferDesc{
		label: c'cube-indices'
	}
	unsafe { vmemset(&index_buffer_desc, 0, int(sizeof(index_buffer_desc))) }
	index_buffer_desc.size = usize(indices.len * int(sizeof(u16)))
	index_buffer_desc.data = gfx.Range{
		ptr: indices.data
		size: usize(indices.len * int(sizeof(u16)))
	}
	index_buffer_desc.@type = .indexbuffer
	ibuf := gfx.make_buffer(&index_buffer_desc)

	// create shader
	shader := gfx.make_shader(C.rt_march_shader_desc(C.sg_query_backend()))

	mut pipdesc := gfx.PipelineDesc{}
	unsafe { vmemset(&pipdesc, 0, int(sizeof(pipdesc))) }
	pipdesc.layout.buffers[0].stride = int(sizeof(Vertex_t))

	// vfmt off
	// the constants [C.ATTR_vs_m_pos, C.ATTR_vs_m_color0, C.ATTR_vs_m_texcoord0] are generated by sokol-shdc
	pipdesc.layout.attrs[C.ATTR_vs_m_pos      ].format = .float3 // x,y,z as f32
	pipdesc.layout.attrs[C.ATTR_vs_m_color0   ].format = .ubyte4n // color as u32
	pipdesc.layout.attrs[C.ATTR_vs_m_texcoord0].format = .float2 // u,v as f32
	// pipdesc.layout.attrs[C.ATTR_vs_m_texcoord0].format  = .short2n  // u,v as u16
	// vfmt on

	pipdesc.shader = shader
	pipdesc.index_type = .uint16

	pipdesc.depth = gfx.DepthState{
		write_enabled: true
		compare: .less_equal
	}
	pipdesc.cull_mode = .back
	pipdesc.label = 'glsl_shader pipeline'.str

	mut bind := gfx.Bindings{}
	unsafe { vmemset(&bind, 0, int(sizeof(bind))) }
	bind.vertex_buffers[0] = vbuf
	bind.index_buffer = ibuf
	bind.fs_images[C.SLOT_tex] = app.texture
	app.bind['march'] = bind

	app.pipe['march'] = gfx.make_pipeline(&pipdesc)

	println('GLSL March init DONE!')
}

// putty shader init
fn init_cube_glsl_p(mut app App) {
	// cube vertex buffer
	// d := u16(32767)     // for compatibility with D3D11, 32767 stand for 1
	d := f32(1.0)
	c := u32(0xFFFFFF_FF) // color RGBA8
	// vfmt off
	vertices := [
		// Face 0
		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
		Vertex_t{ 1.0, -1.0, -1.0, c,  d, 0},
		Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
		Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
		// Face 1
		Vertex_t{-1.0, -1.0,  1.0, c,  0, 0},
		Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
		Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
		// Face 2
		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
		Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
		Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
		Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
		// Face 3
		Vertex_t{ 1.0, -1.0, -1.0, c,  0, 0},
		Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
		Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
		// Face 4
		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
		Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
		Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
		Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
		// Face 5
		Vertex_t{-1.0,  1.0, -1.0, c,  0, 0},
		Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
		Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
	]
	// vfmt off

	mut vert_buffer_desc := gfx.BufferDesc{label: c'cube-vertices'}
	unsafe { vmemset(&vert_buffer_desc, 0, int(sizeof(vert_buffer_desc))) }
	vert_buffer_desc.size = usize(vertices.len * int(sizeof(Vertex_t)))
	vert_buffer_desc.data = gfx.Range{
		ptr: vertices.data
		size: usize(vertices.len * int(sizeof(Vertex_t)))
	}
	vert_buffer_desc.@type = .vertexbuffer
	vbuf := gfx.make_buffer(&vert_buffer_desc)

	/* create an index buffer for the cube */
	// vfmt off
	indices := [
/*
		u16(0), 1,  2,    0,  2,  3,
		     6, 5,  4,    7,  6,  4,
		     8, 9, 10,    8, 10, 11,
*/
		u16(14), 13, 12,    15, 14, 12,
		    16 , 17, 18,    16, 18, 19,
		    22 , 21, 20,    23, 22, 20,
	]
	// vfmt on

	mut index_buffer_desc := gfx.BufferDesc{
		label: c'cube-indices'
	}
	unsafe { vmemset(&index_buffer_desc, 0, int(sizeof(index_buffer_desc))) }
	index_buffer_desc.size = usize(indices.len * int(sizeof(u16)))
	index_buffer_desc.data = gfx.Range{
		ptr: indices.data
		size: usize(indices.len * int(sizeof(u16)))
	}
	index_buffer_desc.@type = .indexbuffer
	ibuf := gfx.make_buffer(&index_buffer_desc)

	// create shader
	shader := gfx.make_shader(C.rt_puppy_shader_desc(C.sg_query_backend()))

	mut pipdesc := gfx.PipelineDesc{}
	unsafe { vmemset(&pipdesc, 0, int(sizeof(pipdesc))) }
	pipdesc.layout.buffers[0].stride = int(sizeof(Vertex_t))

	// vfmt off
	// the constants [C.ATTR_vs_p_pos, C.ATTR_vs_p_color0, C.ATTR_vs_p_texcoord0] are generated by sokol-shdc
	pipdesc.layout.attrs[C.ATTR_vs_p_pos      ].format = .float3  // x,y,z as f32
	pipdesc.layout.attrs[C.ATTR_vs_p_color0   ].format = .ubyte4n // color as u32
	pipdesc.layout.attrs[C.ATTR_vs_p_texcoord0].format = .float2  // u,v as f32
	// pipdesc.layout.attrs[C.ATTR_vs_p_texcoord0].format  = .short2n  // u,v as u16
	// vfmt on

	pipdesc.shader = shader
	pipdesc.index_type = .uint16

	pipdesc.depth = gfx.DepthState{
		write_enabled: true
		compare: .less_equal
	}
	pipdesc.cull_mode = .back

	pipdesc.label = 'glsl_shader pipeline'.str

	mut bind := gfx.Bindings{}
	unsafe { vmemset(&bind, 0, int(sizeof(bind))) }
	bind.vertex_buffers[0] = vbuf
	bind.index_buffer = ibuf
	bind.fs_images[C.SLOT_tex] = app.texture
	app.bind['puppy'] = bind

	app.pipe['puppy'] = gfx.make_pipeline(&pipdesc)

	println('GLSL Puppy init DONE!')
}

[inline]
fn vec4(x f32, y f32, z f32, w f32) m4.Vec4 {
	return m4.Vec4{
		e: [x, y, z, w]!
	}
}

fn calc_tr_matrices(w f32, h f32, rx f32, ry f32, in_scale f32) m4.Mat4 {
	proj := m4.perspective(60, w / h, 0.01, 10.0)
	view := m4.look_at(vec4(f32(0.0), 0, 6, 0), vec4(f32(0), 0, 0, 0), vec4(f32(0), 1,
		0, 0))
	view_proj := view * proj

	rxm := m4.rotate(m4.rad(rx), vec4(f32(1), 0, 0, 0))
	rym := m4.rotate(m4.rad(ry), vec4(f32(0), 1, 0, 0))

	model := rym * rxm
	scale_m := m4.scale(vec4(in_scale, in_scale, in_scale, 1))

	res := (scale_m * model) * view_proj
	return res
}

// march triangles draw
fn draw_cube_glsl_m(app App) {
	if app.init_flag == false {
		return
	}

	ws := gg.window_size_real_pixels()
	ratio := f32(ws.width) / ws.height
	dw := f32(ws.width / 2)
	dh := f32(ws.height / 2)

	rot := [f32(app.mouse_y), f32(app.mouse_x)]
	tr_matrix := calc_tr_matrices(dw, dh, rot[0], rot[1], 2.3)

	gfx.apply_pipeline(app.pipe['march'])
	gfx.apply_bindings(app.bind['march'])

	// Uniforms
	// *** vertex shadeer uniforms ***
	// passing the view matrix as uniform
	// res is a 4x4 matrix of f32 thus: 4*16 byte of size
	vs_uniforms_range := gfx.Range{
		ptr: &tr_matrix
		size: usize(4 * 16)
	}
	gfx.apply_uniforms(.vs, C.SLOT_vs_params_m, &vs_uniforms_range)

	// *** fragment shader uniforms ***
	time_ticks := f32(time.ticks() - app.ticks) / 1000
	// vfmt off
	mut tmp_fs_params := [
		f32(ws.width),
		ws.height * ratio, // x,y resolution to pass to FS
		0,
		0, // dont send mouse position
		/* app.mouse_x,               // mouse x */
		/* ws.height - app.mouse_y*2, // mouse y scaled */
		time_ticks,      // time as f32
		app.frame_count, // frame count
		0,
		0 // padding bytes , see "fs_params" struct paddings in rt_glsl.h
	]!
	// vfmt on
	fs_uniforms_range := gfx.Range{
		ptr: unsafe { &tmp_fs_params }
		size: usize(sizeof(tmp_fs_params))
	}
	gfx.apply_uniforms(.fs, C.SLOT_fs_params_p, &fs_uniforms_range)

	// 3 vertices for triangle * 2 triangles per face * 6 faces = 36 vertices to draw
	gfx.draw(0, (3 * 2) * 3, 1)
}

// puppy triangles draw
fn draw_cube_glsl_p(app App) {
	if app.init_flag == false {
		return
	}

	ws := gg.window_size_real_pixels()
	ratio := f32(ws.width) / ws.height
	dw := f32(ws.width / 2)
	dh := f32(ws.height / 2)

	rot := [f32(app.mouse_y), f32(app.mouse_x)]
	tr_matrix := calc_tr_matrices(dw, dh, rot[0], rot[1], 2.3)

	// apply the pipeline and bindings
	gfx.apply_pipeline(app.pipe['puppy'])
	gfx.apply_bindings(app.bind['puppy'])

	// Uniforms
	// *** vertex shadeer uniforms ***
	// passing the view matrix as uniform
	// res is a 4x4 matrix of f32 thus: 4*16 byte of size
	vs_uniforms_range := gfx.Range{
		ptr: &tr_matrix
		size: usize(4 * 16)
	}
	gfx.apply_uniforms(.vs, C.SLOT_vs_params_p, &vs_uniforms_range)

	// *** fragment shader uniforms ***
	time_ticks := f32(time.ticks() - app.ticks) / 1000
	mut tmp_fs_params := [
		f32(ws.width),
		ws.height * ratio, // x,y resolution to pass to FS
		0,
		0, // dont send mouse position
		// app.mouse_x,               // mouse x
		// ws.height - app.mouse_y*2, // mouse y scaled
		time_ticks, // time as f32
		app.frame_count, // frame count
		0,
		0, // padding bytes , see "fs_params" struct paddings in rt_glsl.h
	]!
	fs_uniforms_range := gfx.Range{
		ptr: unsafe { &tmp_fs_params }
		size: usize(sizeof(tmp_fs_params))
	}
	gfx.apply_uniforms(.fs, C.SLOT_fs_params_p, &fs_uniforms_range)

	// 3 vertices for triangle * 2 triangles per face * 6 faces = 36 vertices to draw
	gfx.draw(0, (3 * 2) * 3, 1)
}

fn draw_start_glsl(app App) {
	if app.init_flag == false {
		return
	}

	ws := gg.window_size_real_pixels()
	// ratio := f32(ws.width) / ws.height
	// dw := f32(ws.width  / 2)
	// dh := f32(ws.height / 2)

	gfx.apply_viewport(0, 0, ws.width, ws.height, true)
}

fn draw_end_glsl(app App) {
	gfx.end_pass()
	gfx.commit()
}

fn frame(mut app App) {
	ws := gg.window_size_real_pixels()

	// clear
	mut color_action := gfx.ColorAttachmentAction{
		action: .clear
		value: gfx.Color{
			r: 0.0
			g: 0.0
			b: 0.0
			a: 1.0
		}
	}
	mut pass_action := gfx.PassAction{}
	pass_action.colors[0] = color_action
	gfx.begin_default_pass(&pass_action, ws.width, ws.height)

	/*
	// glsl cube
	if app.frame_count % 1 == 1{
		draw_cube_glsl_m(app)
	} else {
		draw_cube_glsl_p(app)
	}
	*/
	draw_start_glsl(app)
	draw_cube_glsl_m(app)
	draw_cube_glsl_p(app)
	draw_end_glsl(app)
	app.frame_count++
}

/******************************************************************************
* Init / Cleanup
******************************************************************************/
fn my_init(mut app App) {
	// set max vertices,
	// for a large number of the same type of object it is better use the instances!!
	desc := sapp.create_desc()
	gfx.setup(&desc)
	sgl_desc := sgl.Desc{
		max_vertices: 50 * 65536
	}
	sgl.setup(&sgl_desc)

	// create chessboard texture 256*256 RGBA
	w := 256
	h := 256
	sz := w * h * 4
	tmp_txt := unsafe { malloc(sz) }
	mut i := 0
	for i < sz {
		unsafe {
			y := (i >> 0x8) >> 5 // 8 cell
			x := (i & 0xFF) >> 5 // 8 cell
			// upper left corner
			if x == 0 && y == 0 {
				tmp_txt[i + 0] = u8(0xFF)
				tmp_txt[i + 1] = u8(0)
				tmp_txt[i + 2] = u8(0)
				tmp_txt[i + 3] = u8(0xFF)
			}
			// low right corner
			else if x == 7 && y == 7 {
				tmp_txt[i + 0] = u8(0)
				tmp_txt[i + 1] = u8(0xFF)
				tmp_txt[i + 2] = u8(0)
				tmp_txt[i + 3] = u8(0xFF)
			} else {
				col := if ((x + y) & 1) == 1 { 0xFF } else { 128 }
				tmp_txt[i + 0] = u8(col) // red
				tmp_txt[i + 1] = u8(col) // green
				tmp_txt[i + 2] = u8(col) // blue
				tmp_txt[i + 3] = u8(0xFF) // alpha
			}
			i += 4
		}
	}
	app.texture = create_texture(w, h, tmp_txt)
	unsafe { free(tmp_txt) }

	// glsl
	init_cube_glsl_m(mut app)
	init_cube_glsl_p(mut app)
	app.init_flag = true
}

/******************************************************************************
* events handling
******************************************************************************/
fn my_event_manager(mut ev gg.Event, mut app App) {
	if ev.typ == .mouse_down {
		app.mouse_down = true
	}
	if ev.typ == .mouse_up {
		app.mouse_down = false
	}
	if app.mouse_down == true && ev.typ == .mouse_move {
		app.mouse_x = int(ev.mouse_x)
		app.mouse_y = int(ev.mouse_y)
	}
	if ev.typ == .touches_began || ev.typ == .touches_moved {
		if ev.num_touches > 0 {
			touch_point := ev.touches[0]
			app.mouse_x = int(touch_point.pos_x)
			app.mouse_y = int(touch_point.pos_y)
		}
	}
}

/******************************************************************************
* Main
******************************************************************************/
fn main() {
	// App init
	mut app := &App{
		gg: 0
	}

	app.gg = gg.new_context(
		width: win_width
		height: win_height
		create_window: true
		window_title: '3D Dual shader Cube - click and rotate with the mouse'
		user_data: app
		bg_color: bg_color
		frame_fn: frame
		init_fn: my_init
		event_fn: my_event_manager
	)

	app.ticks = time.ticks()
	app.gg.run()
}