require 'honey.std'

local glfw = honey.glfw
local gl = honey.gl
local Vec3 = honey.Vec3
local Mat4 = honey.Mat4
local Quaternion = honey.Quaternion
local ecs = honey.ecs
local systems = honey.standardSystems
local ode = honey.ode
local nvg = honey.nvg


-- initialize honey
local window = honey.init()

-- setup vector graphics
local vg = nvg.CreateContext()
local november = nvg.CreateFont(vg, "November", "assets/november.regular.ttf")
local vw, vh = 640, 480


-- create camera matrices
local camera = {
	view=Mat4():identity():translate(Vec3{0, 0, -30}),
	projection=Mat4():perspective(math.rad(45), 640/480, 0.1, 100),
}



-- create shader
local shader = honey.Shader{
	vertexFile = "vertex.glsl",
	fragmentFile = "fragment.glsl",
}

-- load models
local plane = honey.mesh.loadFile("assets/plane.obj")[1]
local tetra = honey.mesh.loadFile("assets/tetrahedron.obj")[1]
local cube = honey.mesh.loadFile("assets/cube.obj")[1]
local octa = honey.mesh.loadFile("assets/octahedron.obj")[1]
local dodeca = honey.mesh.loadFile("assets/dodecahedron.obj")[1]
local icosa  = honey.mesh.loadFile("assets/icosahedron.obj")[1]


-- close window on ESCAPE key
window:setKeyCallback(function(_, key, scancode, action)
	if action == glfw.PRESS then
		if key == glfw.KEY_ESCAPE then
			window:setShouldClose(true)
		end
	end
end)

-- resize window correctly
window:setFramebufferSizeCallback(function(_, width, height)
	gl.Viewport(0, 0, width, height)
	camera.projection:perspectiveResize(width/height)
	vw, vh = width, height
end)

-- averager (for fps)
function averager(memory)
	local buf = {}
	local avg = 0
	for i=1,memory do table.insert(buf, 0) end
	return function(value)
		table.insert(buf, value)
		local val = table.remove(buf, 1)
		avg = avg + value - val
		return avg / memory
	end
end
local fpsAverage = averager(200)


-- setup ecs
local edb = ecs.EntityDb()
local sdb = ecs.SystemDb()

sdb:addSystem{
	update = function(self, dt)
		local entities = self.db:queryComponent("renderMesh")
		for entity, tbl in pairs(entities) do
			tbl.shader:use()
			tbl.shader:configure{matrix={
				view=camera.view,
				projection=camera.projection,
				model=Mat4():identity(),
			}}
			local mesh = honey.mesh.loadMesh(tbl.mesh.filename, tbl.mesh.index)
			mesh:drawElements()
		end
	end,
	db = edb,
	priority = 99,
}


local id = edb:createEntity()
edb:addComponent(id, "renderMesh", {
	shader = shader,
	mesh = { filename="assets/icosahedron.obj", index=1 },
})



-- main loop
honey.loop(window, function(dt)
	gl.ClearColor(0.2, 0.4, 1.0, 1.0)
	gl.Clear(gl.COLOR_BUFFER_BIT + gl.DEPTH_BUFFER_BIT + gl.STENCIL_BUFFER_BIT)

	gl.Enable(gl.DEPTH_TEST)
	gl.Disable(gl.CULL_FACE)

	sdb:update(dt)
	nvg.BeginFrame(vg, vw, vh, 1.0)
	nvg.StrokeColor(vg, nvg.RGBf(1, 1, 1))
	nvg.FontFace(vg, "November")
	nvg.Text(vg, 50, 50, "fps: "..tostring(math.floor(fpsAverage(1/dt))))
	nvg.BeginPath(vg)
	nvg.MoveTo(vg, 50, 50)
	nvg.LineTo(vg, 50, 100)
	nvg.LineTo(vg, 100, 50)
	nvg.Stroke(vg)
	nvg.EndFrame(vg)
end)

-- clean up
honey.terminate()