local path = env().argv[1]
local output_path = string.sub(path,1,string.find(path,".obj$")).."ptm"

local material_lookup = {}

local material = nil

local obj = {
	v = {},
	vt = {},
	vp = {},
	f = {},
}

-- Each element in an obj starts with an identifier.
-- We can use this identifier to determine how to interpret
-- the rest of the line.
local interps = {
	v = function(ln)
		add(obj.v,vec(ln[2],ln[3],ln[4],1))
	end,
	vt = function(ln)
		add(obj.vt,vec(ln[2],ln[3]))
	end,
	vp = function(ln)
		add(obj.vp,vec(ln[2],ln[3],ln[4]))
	end,
	usemtl = function(ln)
		material = ln[2]
	end,
	f = function(ln)
		local f = {}
		if material_lookup[material] then
			f.mat_index = material_lookup[material]
		else
			add(material_lookup,material)
			material_lookup[material] = #material_lookup
			f.mat_index = #material_lookup
		end

		for i = #ln,2,-1 do
			local indices = split(ln[i],"/")
			local v = {}

			v.v = indices[1]
			if indices[2] ~= "" then v.vt = indices[2] end
			v.vn = indices[3]

			add(f,v)
		end

		add(obj.f,f)
	end,
}

for l in all(split(fetch(path),"\n")) do
	local tokens = split(l," ")
	local interpreter = interps[tokens[1] ]
	if interpreter then interpreter(tokens) end
end

local pts = userdata("f64",4,#obj.v)
for i = 1,#obj.v do
	local v = obj.v[i]
	pts:set(0,i-1,v[0],v[1],v[2],v[3])
end

local uvs = userdata("f64",2,#obj.vt)
for i = 1,#obj.vt do
	local vt = obj.vt[i]
	uvs:set(0,i-1,vt[0],1-vt[1]) -- Top to bottom instead of bottom to top.
end

local materials = {}
for i = 1,#material_lookup do
	add(materials,material_lookup[i])
end

local pt_indices = userdata("f64",3,#obj.f)
local uv_indices = userdata("f64",3,#obj.f)
local material_indices = userdata("f64",#obj.f)

for i = 1,#obj.f do
	local face = obj.f[i]
	material_indices[i-1] = face.mat_index
	local v1,v2,v3 = face[1],face[2],face[3]

	-- Subtract 1 from each index to convert to 0-based.
	pt_indices:set(0,i-1,v1.v-1,v2.v-1,v3.v-1)
	uv_indices:set(0,i-1,v1.vt-1,v2.vt-1,v3.vt-1)
end

local output = {
	pts = pts,
	uvs = uvs,
	materials = materials,

	pt_indices = pt_indices,
	uv_indices = uv_indices,
	material_indices = material_indices,
}

local icon = userdata("u8",16,16,"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")

store(output_path,pod(output,0b111),{icon = icon})