1 files changed, 93 insertions, 0 deletions
diff --git a/channel.lua b/channel.lua
new file mode 100644
index 0000000..2885e68
--- /dev/null
+++ b/channel.lua
@@ -0,0 +1,93 @@
+-- bi-directional http-channel
+-- with long-poll GET and POST on the same URL
+
+local debug = true
+
+local function Channel(http, url, cfg)
+	cfg = cfg or {}
+	local extra_headers = cfg.extra_headers or {}
+	local timeout = cfg.timeout or 1
+	local long_poll_timeout = cfg.long_poll_timeout or 30
+	local error_retry = cfg.error_retry or 10
+
+	-- assemble post-header with json content
+	local post_headers = { "Content-Type: application/json" }
+	for _,header in pairs(cfg.extra_headers) do
+		table.insert(post_headers, header)
+	end
+
+	local recv_listeners = {}
+	local run = true
+
+	local recv_loop
+
+	recv_loop = function()
+		assert(run)
+
+		-- long-poll GET
+		http.fetch({
+			url = url,
+			extra_headers = extra_headers,
+			timeout = long_poll_timeout
+		}, function(res)
+			if res.succeeded and res.code == 200 then
+				local data = minetest.parse_json(res.data)
+
+				if debug then
+					minetest.log("action", "[webmail-rx] " .. dump(data))
+				end
+
+				if data then
+					for _,listener in pairs(recv_listeners) do
+						listener(data)
+					end
+				end
+				-- reschedule immediately
+				minetest.after(0, recv_loop)
+			else
+				-- error, retry after some time
+				minetest.after(error_retry, recv_loop)
+			end
+		end)
+	end
+
+
+	local send = function(data)
+		assert(run)
+		-- POST
+
+		if debug then
+			minetest.log("action", "[webmail-tx] " .. dump(data))
+		end
+
+		http.fetch({
+			url = url,
+			extra_headers = post_headers,
+			timeout = timeout,
+			post_data = minetest.write_json(data)
+		}, function(res)
+			-- TODO: error-handling
+		end)
+	end
+
+	local receive = function(listener)
+		table.insert(recv_listeners, listener)
+	end
+
+	local close = function()
+		run = false
+	end
+
+	recv_loop();
+
+	return {
+		send = send,
+		receive = receive,
+		close = close
+	}
+
+end
+
+
+
+return Channel