Internet API

-- Variables --
pageCache = {}
-- File sizes.
kilobytes = 1024
megabytes = 1024*1024
gigabytes = 1024*1024*1024
terabytes = 1024*1024*1024*1024
KB = kilobytes
MB = megabytes
GB = gigabytes
TB = terabytes

-- Configuration --
defaultBrowserLocation = "browser"
cacheLocation = "internetCache"
cacheEnabled = fs.getFreeSpace("") > 1*MB
maxPageCacheSize = 20*MB

local oget, opost, orequest

if http then
	if not http.Modified then
		oget = http.get
		opost = http.post
		orequest = http.request
	end
end

function serializeCacheLocation(url, postData, headers)
	return cacheLocation.."/"..tostring(string.sub(url or "none", 6, -1).."/"..(string.sub(postData or "none", 1, 20) or "none").."/"..(string.sub(textutils.serialize(headers or {}) or "none", 1, 20) or "none"))
end

-- This function adds a page to the page cache.
function addToCache(url, postData, headers, handle)
	local findStr = serializeCacheLocation(url, postData, headers)
	fs.makeDir(cacheLocation)
	fs.makeDir(cacheLocation.."/"..string.sub(url or "none", 6, -1))
	fs.makeDir(cacheLocation.."/"..string.sub(url or "none", 6, -1).."/"..(string.sub(postData or "none", 1, 20) or "none"))
	local file = fs.open(findStr, "w")
	if file then
		file.writeLine(handle.getResponseCode() or "100")
		file.write(handle.readAll())
		file.close()
		return true
	end
end


function pullFromCache(url, postData, headers)
	local findStr = serializeCacheLocation(url, postData, headers)
	local file = fs.open(findStr, "r")
	if file then
		--os.queueEvent( "http_success", url, file )
		file.responseCode = tonumber(file.readLine())
		file.getResponseCode = function()
			return file.responseCode
		end
		return file
	end
	return false
end

-- Override the final http functions with ones that pull files from the cache.
if http then
	if oget and cacheEnabled then
		function request(url, postData, headers)
			local url, file = pullFromCache(url, postData, headers)
			if file then
				os.queueEvent( "http_success", url, file )
			end
			orequest(url or "", postData, headers)
		end
		function get(url, headers)
			if not string.find(url, "pastebin.com") then
				local url1, file = pullFromCache(url, nil, headers)
				if file then
					return file
				end
			end
			local handle, err = oget(url, headers)
			if handle then
				addToCache(url, nil, headers, handle)
			end
			return pullFromCache(url, nil, headers)
		end
		function post(url, postData, headers)
			local url1, file = pullFromCache(url, postData, headers)
			if file then
				return file
			end
			local handle, err = opost(url, postData, headers)
			if handle then
				pcall(addToCache, url, postData, headers, handle)
			end
			return handle, err
		end
		http.get = get
		http.post = post
		http.request = request
	end
end

function resetCache()
	for k, v in ipairs(fs.list(cacheLocation)) do
		fs.delete(cacheLocation.."/"..v)
	end
end

function overwriteFileRaw(contents, destination)
	local file, err = fs.open(destination, "w")
	if file then
		file.write(contents)
		file.close()
		return true
	end
	return false, err
end

-- Overwrites a file with the contents you give as the first argument.
function overwriteFile(contents, destination)
	local pcallSuccess, returnCondition, errorString = pcall(overwriteFileRaw, contents, destination)
	if pcallSuccess then
		return returnCondition, errorString
	end
	return false, returnCondition
end

function pullFileRaw(url, header, post)
	if http then
		local handle, str
		if not post then
			handle, str = http.get(url, header), ""
		else
			handle, str = http.post(url, post, header), ""
		end
		if handle then
			str = handle.readAll()
			handle.close()
		end
		return str
	end
	return false, "Http API is not enabled"
end

-- Downloads a file from the internet.
-- The url is the file to download.
function pullFile(url, header, post)
	local pcallSuccess, returnCondition, errorString = pcall(pullFileRaw, url, header, post)
	if pcallSuccess then
		return returnCondition, errorString
	end
	return false, returnCondition
end


-- Downloads a file from the internet.
-- The url is the file to download, and the destination is what file will be overwritten.
function downloadFileRaw(url, destination, header, post)
	if http then
		local handle, str
		if not post then
			handle, str = http.get(url, header), ""
		else
			handle, str = http.post(url, post, header), ""
		end
		if handle then
			str = handle.readAll()
			handle.close()
			return overwriteFile(str, destination)
		end
		return str
	end
	return false, "Http API is not enabled"
end

-- Downloads a file from the internet.
-- The url is the file to download, and the destination is what file will be overwritten.
function downloadFile(url, destination, header, post)
	local pcallSuccess, returnCondition, errorString = pcall(downloadFileRaw, url, destination, header, post)
	if pcallSuccess then
		return returnCondition, errorString
	end
	return false, returnCondition
end

-- Opens the default web browser.
function openInternetBrowser(url)
	if not fs.exists(defaultBrowserLocation) then
		shell.run("pastebin get VDUGPdiA "..defaultBrowserLocation)
	end
	shell.run(defaultBrowserLocation, url)
end