[plugin] NewsDownloader: fix XML, better error messages, change default feed, and more (#8145)

* Fix XML, introduce some better error messages, etc.

See roygbyte/newsdownloader.koplugin for more info

* Fix feed attribute saving snafu; Change menu labels; etc.

Also:
- Change default feed
- Change "remove" label to "delete"
- Hide menu after feed sync

plugins/newsdownloader.koplugin/feed_config.lua

@@ -33,10 +33,7 @@ return {--do NOT change this line
 
  -- LIST YOUR FEEDS HERE:
 
- { "http://feeds.reuters.com/Reuters/worldNews?format=xml", limit = 2, download_full_article=true, include_images=true, enable_filter=true},
-
- { "https://www.pcworld.com/index.rss", limit = 7 , download_full_article=false},
-
--- { "http://www.football.co.uk/international/rss.xml", limit = 2},
+ { "https://github.com/koreader/koreader/releases.atom", limit = 3, download_full_article=true, include_images=false, enable_filter=true, filter_element = "div.release-main-section"},
+ { "https://ourworldindata.org/atom.xml", limit = 5 , download_full_article=true, include_images=true, enable_filter=false, filter_element = ""},
 
 }--do NOT change this line

plugins/newsdownloader.koplugin/feed_view.lua

@@ -0,0 +1,210 @@
+local logger = require("logger")
+local _ = require("gettext")
+
+local FeedView = {
+    URL = "url",
+    LIMIT = "limit",
+    DOWNLOAD_FULL_ARTICLE = "download_full_article",
+    INCLUDE_IMAGES = "include_images",
+    ENABLE_FILTER = "enable_filter",
+    FILTER_ELEMENT = "filter_element"
+}
+
+function FeedView:getList(feed_config, callback, edit_feed_attribute_callback, delete_feed_callback)
+    local view_content = {}
+    -- Loop through the feed.
+    for idx, feed in ipairs(feed_config) do
+        local feed_item_content = {}
+        local feed_list_content = {}
+
+        local vc_feed_item = FeedView:getItem(
+            idx,
+            feed,
+            edit_feed_attribute_callback,
+            delete_feed_callback
+        )
+
+        if not vc_feed_item then
+            logger.warn('NewsDownloader: invalid feed config entry', feed)
+        else
+            feed_item_content = FeedView:flattenArray(feed_item_content, vc_feed_item)
+            local url = feed[1]
+            table.insert(
+                view_content,
+                {
+                    url,
+                    "",
+                    callback = function()
+                        -- Here is where we trigger the single feed item display
+                        callback(feed_item_content)
+                    end
+                }
+            )
+            -- Insert a divider.
+            table.insert(
+                view_content,
+                "---"
+            )
+        end
+    end
+    return view_content
+end
+
+function FeedView:getItem(id, feed, edit_feed_callback, delete_feed_callback)
+
+    logger.dbg("NewsDownloader:", feed)
+
+    local url = feed[1]
+    local limit = feed.limit
+
+    -- If there's no URL or limit we don't care about this
+    -- because we can't use it.
+    if not url and limit then
+        return nil
+    end
+
+    -- Collect this stuff for later, with the single view.
+    local download_full_article = feed.download_full_article == nil
+        or feed.download_full_article
+    local include_images = not never_download_images
+        and feed.include_images
+    local enable_filter = feed.enable_filter
+        or feed.enable_filter == nil
+    local filter_element = feed.filter_element
+        or feed.filter_element == nil
+
+    --- @todo: Strip the http:// or https:// from the URL
+    local sPre, sLink, sPost = url:match( "(.+)%s+(https?%S+)%s+(.*)$" )
+    local pretty_url = sLink
+
+    local view_content = {}
+    local vc = {
+        {
+            _("URL"),
+            url,
+            callback = function()
+                edit_feed_callback(
+                    id,
+                    FeedView.URL,
+                    url
+                )
+            end
+        },
+        {
+            _("Limit"),
+            limit,
+            callback = function()
+                edit_feed_callback(
+                    id,
+                    FeedView.LIMIT,
+                    limit
+                )
+            end
+        },
+        {
+            _("Download full article"),
+            download_full_article,
+            callback = function()
+                edit_feed_callback(
+                    id,
+                    FeedView.DOWNLOAD_FULL_ARTICLE,
+                    download_full_article
+                )
+            end
+        },
+        {
+            _("Include images"),
+            include_images,
+            callback = function()
+                edit_feed_callback(
+                    id,
+                    FeedView.INCLUDE_IMAGES,
+                    include_images
+                )
+            end
+        },
+        {
+            _("Enable filter"),
+            enable_filter,
+            callback = function()
+                edit_feed_callback(
+                    id,
+                    FeedView.ENABLE_FILTER,
+                    enable_filter
+                )
+            end
+
+        },
+        {
+            _("Filter element"),
+            filter_element,
+            callback = function()
+                edit_feed_callback(
+                    id,
+                    FeedView.FILTER_ELEMENT,
+                    filter_element
+                )
+            end
+        },
+    }
+
+    -- We don't always display this. For instance: if a feed
+    -- is being created, this button is not necessary.
+    if delete_feed_callback then
+        table.insert(
+            vc,
+            "---"
+        )
+        table.insert(
+            vc,
+            {
+                _("Delete feed"),
+                "",
+                callback = function()
+                    delete_feed_callback(
+                        id
+                    )
+                end
+            }
+        )
+    end
+
+    return vc
+end
+
+--
+-- KeyValuePage doesn't like to get a table with sub tables.
+-- This function flattens an array, moving all nested tables
+-- up the food chain, so to speak
+--
+function FeedView:flattenArray(base_array, source_array)
+    for key, value in pairs(source_array) do
+        if value[2] == nil then
+            -- If the value is empty, then it's probably supposed to be a line
+            table.insert(
+                base_array,
+                "---"
+            )
+        else
+            if value["callback"] then
+                table.insert(
+                    base_array,
+                    {
+                        value[1], value[2], callback = value["callback"]
+                    }
+                )
+            else
+                table.insert(
+                    base_array,
+                    {
+                        value[1], value[2]
+                    }
+                )
+            end
+        end
+    end
+    return base_array
+end
+
+
+return FeedView