Refactor ContentDB integration (#14507)

builtin/mainmenu/content/screenshots.lua

@@ -0,0 +1,78 @@
+--Minetest
+--Copyright (C) 2023-24 rubenwardy
+--
+--This program is free software; you can redistribute it and/or modify
+--it under the terms of the GNU Lesser General Public License as published by
+--the Free Software Foundation; either version 2.1 of the License, or
+--(at your option) any later version.
+--
+--This program is distributed in the hope that it will be useful,
+--but WITHOUT ANY WARRANTY; without even the implied warranty of
+--MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+--GNU Lesser General Public License for more details.
+--
+--You should have received a copy of the GNU Lesser General Public License along
+--with this program; if not, write to the Free Software Foundation, Inc.,
+--51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+
+-- Screenshot
+local screenshot_dir = core.get_cache_path() .. DIR_DELIM .. "cdb"
+assert(core.create_dir(screenshot_dir))
+local screenshot_downloading = {}
+local screenshot_downloaded = {}
+
+
+local function get_file_extension(path)
+	local parts = path:split(".")
+	return parts[#parts]
+end
+
+
+function get_screenshot(package)
+	if not package.thumbnail then
+		return defaulttexturedir .. "no_screenshot.png"
+	elseif screenshot_downloading[package.thumbnail] then
+		return defaulttexturedir .. "loading_screenshot.png"
+	end
+
+	-- Get tmp screenshot path
+	local ext = get_file_extension(package.thumbnail)
+	local filepath = screenshot_dir .. DIR_DELIM ..
+			("%s-%s-%s.%s"):format(package.type, package.author, package.name, ext)
+
+	-- Return if already downloaded
+	local file = io.open(filepath, "r")
+	if file then
+		file:close()
+		return filepath
+	end
+
+	-- Show error if we've failed to download before
+	if screenshot_downloaded[package.thumbnail] then
+		return defaulttexturedir .. "error_screenshot.png"
+	end
+
+	-- Download
+
+	local function download_screenshot(params)
+		return core.download_file(params.url, params.dest)
+	end
+	local function callback(success)
+		screenshot_downloading[package.thumbnail] = nil
+		screenshot_downloaded[package.thumbnail] = true
+		if not success then
+			core.log("warning", "Screenshot download failed for some reason")
+		end
+		ui.update()
+	end
+	if core.handle_async(download_screenshot,
+			{ dest = filepath, url = package.thumbnail }, callback) then
+		screenshot_downloading[package.thumbnail] = true
+	else
+		core.log("error", "ERROR: async event failed")
+		return defaulttexturedir .. "error_screenshot.png"
+	end
+
+	return defaulttexturedir .. "loading_screenshot.png"
+end