--- LuaDist URL fetch functions
-- Peter Drahos, LuaDist Project, 2008

module ("dist.fetch", package.seeall)

local config 	= require "dist.config"
local sys 		= require "dist.sys"
local curl 		= require "luacurl"

--- Fetch file from URL.
-- @param src sting: URL to fetch file from.
-- @param dest sting: Destination to save download to or nil for temp directory.
-- @param callback function: Callback function that will provide download progress feedback. function(src, downloaded, total)
-- @return path, err: Path the file was downloaded or nil and error message on failure.
function download(src, dest, callback)
	assert(type(src)=="string", "download argument 'src' is not a string.")
	assert(not dest or type(dest)=="string", "download argument 'dest' is not a string.")
	assert(not callback or type(callback)=="function", "download argument 'callback' is not a function.")
	dest = dest or config.temp
	
	local file = src:match("([^/]+)$")
	if not file then return nil, "Could not determine filename." end
	if not sys.isDir(dest) then return nil, "Destination directory does not exist." end
	dest = dest .. "/" .. file
	
	local c = assert(curl.new(), "Could not initialize Curl.")
	local file = assert(io.open(dest, "wb"))
	assert(c:setopt(curl.OPT_WRITEFUNCTION, function (stream, buffer)
		stream:write(buffer)
		return string.len(buffer)
	end), "Could not initialize Curl write function.")
	assert(c:setopt(curl.OPT_WRITEDATA, file))
	if callback then
		assert(c:setopt(curl.OPT_PROGRESSFUNCTION, function (_, dltotal, dlnow, uptotal, upnow)
			cballback(src, dlnow, dltotoal)
		end), "Could not initialize Curl download progress function.")
	end
	if config.verbose then assert(c:setopt(curl.OPT_VERBOSE, true)) end
	-- assert(c:setopt(curl.OPT_NOPROGRESS, true), "Could not set Curl parameter OPT_NOPROGRESS.")
	assert(c:setopt(curl.OPT_BUFFERSIZE, 2^13), "Could not set Curl parameter OPT_BUFFERSIZE.")
	assert(c:setopt(curl.OPT_HTTPHEADER, "Connection: Keep-Alive", "Accept-Language: en-us"), "Could not set Curl parameter OPT_HTTPHEADER.")
	assert(c:setopt(curl.OPT_URL, src), "Could not set Curl parameter OPT_URL.")
	assert(c:setopt(curl.OPT_CONNECTTIMEOUT, 15), "Could not set Curl parameter OPT_CONNECTTIMEOUT.")
	local ok, err = c:perform()
	file:close()
	if not ok then return false, err end
	return dest
end

--- Directly get file contents from URL.
-- @param src string: URL of the file to load.
-- @return text, err: Contents of the URL file or nil and error message on failure.
function get(src)
	local c = assert(curl.new(), "Could not initialize Curl.")
	local file = ""
	assert(c:setopt(curl.OPT_WRITEFUNCTION, function (stream, buffer)
		file = file .. buffer
		return string.len(buffer)
	end));
	-- assert(c:setopt(curl.OPT_WRITEDATA, nil))
	-- assert(c:setopt(curl.OPT_NOPROGRESS, true))
	assert(c:setopt(curl.OPT_BUFFERSIZE, 2^13), "Could not set Curl parameter OPT_BUFFERSIZE.")
	assert(c:setopt(curl.OPT_HTTPHEADER, "Connection: Keep-Alive", "Accept-Language: en-us"), "Could not set Curl parameter OPT_HTTPHEADER.")
	assert(c:setopt(curl.OPT_URL, src), "Could not set Curl parameter OPT_URL.")
	assert(c:setopt(curl.OPT_CONNECTTIMEOUT, 15), "Could not set Curl parameter OPT_CONNECTTIMEOUT.")
	local ok, err = c:perform()
	if ok then
		return file
	end
	return nil, err
end