feat: Update checker (#16)

* When there is a new version available, the update checker will alert the user that a new version is available

_meta.lua

@@ -3,5 +3,5 @@ return {
     name = "askgpt",
     fullname = _("AskGPT"),
     description = _([[Allows the user to query the ChatGPT API for answers to questions about highlighted text.]]),
-    version = 0.9,
+    version = 1.0,
 }

main.lua

@@ -4,6 +4,7 @@ local NetworkMgr = require("ui/network/manager")
 local _ = require("gettext")
 
 local showChatGPTDialog = require("dialogs")
+local UpdateChecker = require("update_checker")
 
 local AskGPT = InputContainer:new {
   name = "askgpt",
@@ -16,7 +17,10 @@ function AskGPT:init()
       text = _("Ask ChatGPT"),
       enabled = Device:hasClipboard(),
       callback = function()
-        NetworkMgr:runWhenOnline(function() showChatGPTDialog(self.ui, _reader_highlight_instance.selected_text.text) end)
+        NetworkMgr:runWhenOnline(function()
+          UpdateChecker.checkForUpdates()
+          showChatGPTDialog(self.ui, _reader_highlight_instance.selected_text.text)
+        end)
       end,
     }
   end)

update_checker.lua

@@ -0,0 +1,40 @@
+local http = require("socket.http")
+local ltn12 = require("ltn12")
+local json = require("json")
+local meta = require("_meta")
+local InfoMessage = require("ui/widget/infomessage")
+local UIManager = require("ui/uimanager")
+
+local function checkForUpdates()
+  local response_body = {}
+  local _, code = http.request {
+    url = "https://api.github.com/repos/drewbaumann/AskGPT/releases/latest",
+    headers = {
+        ["Accept"] = "application/vnd.github.v3+json"
+    },
+    sink = ltn12.sink.table(response_body)
+  }
+
+  if code == 200 then
+    local data = table.concat(response_body)
+    local parsed_data = json.decode(data)
+    local latest_version = parsed_data.tag_name -- e.g., "v0.9"
+    local stripped_latest_version = latest_version:match("^v(.+)$")
+    -- Compare with current version
+    if meta.version < tonumber(stripped_latest_version) then
+      -- Show notification to the user if a new version is available
+      local message = "A new version of the app (" .. latest_version .. ") is available. Please update!"
+      local info_message = InfoMessage:new{
+          text = message,
+          timeout = 5 -- Display message for 5 seconds
+      }
+      UIManager:show(info_message)
+    end
+  else
+    print("Failed to check for updates. HTTP code:", code)
+  end
+end
+
+return {
+  checkForUpdates = checkForUpdates
+}