--CCPT - ComputerCraft Packaging Tool

if not http then
error("HTTP API MUST be enabled to use this program")
end

--Pseudo enums

local validator = {ok = 0, installed = 1, file_conflict = 2}

---UTILITIES

local function CGetS(file,name)
	local _cfg = fs.open(file,"r")
	
	if not _cfg then
		error("Could not open configuration file: "..file)
	end
	
	local x = true;
	 
	while x do
		local line = _cfg.readLine()
		if line == nil then
			x = false;
		else
		 
			local side = false
			local prop = ""
			local val = ""
			for a=1,#line do
				if line:sub(a,a) == '=' then
					side = true
				elseif side then
					val =  val .. line:sub(a,a)
				else
					prop = prop .. line:sub(a,a)
				end
			end
			
			if prop == name then
				_cfg.close()
				return val
			end			
		end	 
	end
	_cfg.close()	
end
 
local function CGetN(file,name)
	return tonumber(CGetS(file,name))
end

local function download(file, url)
	local res = http.get(url)
	if res then
		if file ~= nil then
			local fhnd = fs.open(file, "w");
			if fhnd then
				fhnd.write(res.readAll())
				fhnd.close()
				return res.readAll()
			else
				res.close()
				error("Could not open "..file.." for writing")
			end
		else
			return res.readAll()
		end
	else
		error("Download failed for: "..url)
	end
	res.close()
end

function split(text,splitter)
	local rt = {}
	local act = ""
	for x=1,#text do
		if text:sub(x,x+#splitter-1) == splitter then
			rt[#rt+1]=act
			act=""
		else
			act = act .. text:sub(x,x)
		end
	end
	if act ~= "" then
		rt[#rt+1] = act
	end
	return rt;
end

---Intarnal functions

local function update_list()
	local sync = CGetS("/etc/ccpt/config","master")
	if sync then 
		download("/etc/ccpt/list",sync)
	else
		error("Update failed: master server not set!")
	end
end

local function base_find(name)
	local base = fs.open("/etc/ccpt/list","r")
	
	if not base then
		error("Could not open base file: /etc/ccpt/list")
	end
	
	local x = true;
	while x do 
		local line = base.readLine()
		if line == nil then
			x = false;
		else
			local entry = split(line,";")
			if entry[1] == "p" then
				if entry[2] == name then
					local ret = {name=entry[2],url=entry[4],version=tonumber(entry[3])}
					return ret
				end
			end
		end
	end
end

local function validate(pname,header)
	local instbase = fs.open("/etc/ccpt/installed","r")
	if instbase then
		local x = true
		while x do
			local tline = instbase.readLine()
			if tline == nil then
				x = false
			else
				if pname == split(tline,";")[1] then
					return validator.installed
				end
			end
		end
	end
	--local filebase = fs.open("/etc/ccpt/files","r")
	lhead = split(header,"\n")
	local x = 1
	for x = 1, #lhead do
		if split(lhead[x],";")[1] == "f" then
			if fs.exists(split(lhead[x],";")[2]) then
				return validator.file_conflict
			end
		end
	end
	
	return validator.ok
end

local function download_files(url,header)
lhead = split(header,"\n")
	local x = 1
	for x = 1, #lhead do
		if split(lhead[x],";")[1] == "f" then
			download(split(lhead[x],";")[2],url..split(lhead[x],";")[2])
		end
	end
end
---MAIN CODE

local argv = {...}
if     argv[1] == "init"   then
	print("Installing directories")
	fs.makeDir("/etc/")
	fs.makeDir("/etc/ccpt")
	fs.makeDir("/bin/")
	fs.makeDir("/usr/")
	fs.makeDir("/usr/bin")
	fs.makeDir("/usr/lib")
	fs.makeDir("/usr/share")
	print("Downloading default config")
	download("/etc/ccpt/config","http://cc.nativehttp.org/fresh/config")
	print("Updating package list")
	update_list()
elseif argv[1] == "update" then
	print("Updating package list")
	update_list()
elseif argv[1] == "install" then
	if argv[2] == nil then
		print("Usage: ccpk install [name]")
	else
		print("Reading Database")
		local entry = base_find(argv[2])
		if entry then
			print("Downloading package header")
			local header = download(nil, entry.url..entry.name.."/index")
			print("Checking for conflicts")
			local vres = validate(entry.name,header)
			if vres == validator.ok then
				print("Downloading files")
				download_files(entry.url,header)
			elseif vres == validator.installed then
				print("Package already installed")
			else
				print("File conflict detected!")
			end
		else
			print("Package not found!")
		end
	end
end