process later download requests first

2 files changed, 33 insertions, 2 deletions

diff --git a/iptv-menu-dl.lua b/iptv-menu-dl.lua
index 9ff4650..a207c91 100644
--- a/iptv-menu-dl.lua
+++ b/iptv-menu-dl.lua
@@ -2,7 +2,9 @@
 
 local utils = require('mp.utils')
 
-mp.register_script_message('download-image', function(target, name, url, path)
+local queue = {}
+
+function download(target, name, url, path)
 	if utils.file_info(path) then
 		return
 	end
@@ -14,4 +16,33 @@ mp.register_script_message('download-image', function(target, name, url, path)
 	if ret == 0 then
 		mp.commandv('script-message-to', target, name, url, path)
 	end
+end
+
+function process_next()
+	download(unpack(table.remove(queue)))
+
+	if #queue > 0 then
+		mp.add_timeout(0, process_next)
+	end
+end
+
+mp.register_script_message('download-file', function(...)
+	queue[#queue+1] = {...}
+
+	-- we want the ability for a later request to be downloaded before
+	-- earlier ones, e.g., to prioritise the image for the current menu.
+	--
+	-- using a small timeout between receiving a message and processing it
+	-- allows for multiple pending messages to be received before any are
+	-- processed. however, immediately scheduling a timer for each request
+	-- does not work, as all elapsed timeouts are executed before any new
+	-- messages are received.
+	--
+	-- the workaround is to schedule a timeout only when adding to an empty
+	-- queue and have each callback schedule an additional timeout if the
+	-- queue is not empty after completion. this effectively results in new
+	-- messages being received after each download.
+	if #queue == 1 then
+		mp.add_timeout(0, process_next)
+	end
 end)
diff --git a/main.lua b/main.lua
index 396e300..d50f5f3 100644
--- a/main.lua
+++ b/main.lua
@@ -139,7 +139,7 @@ local function get_image_path(url, dl)
 
 	if dl then
 		mp.commandv('script-message-to',
-			'iptv_menu_dl', 'download-image',
+			'iptv_menu_dl', 'download-file',
 			script_name, 'downloaded-image', -- callback
 			url, path)
 		return path