Add DecSync plugin

.gitmodules

@@ -2,3 +2,6 @@
 	path = data/GrabberConfig
 	url = https://github.com/fivefilters/ftr-site-config
     branch = master
+[submodule "libdecsync"]
+	path = plugins/backend/decsync/libdecsync
+	url = https://github.com/39aldo39/libdecsync-vala

meson_options.txt

@@ -6,7 +6,7 @@ option('share-plugins',
 )
 option('backend-plugins',
         type: 'array',
-        choices: ['bazqux', 'feedbin', 'feedhq', 'feedly', 'fresh', 'inoreader', 'local', 'oldreader', 'owncloud', 'ttrss'],
-        value : ['bazqux', 'feedbin', 'feedhq', 'feedly', 'fresh', 'inoreader', 'local', 'oldreader', 'owncloud', 'ttrss'],
+        choices: ['bazqux', 'decsync', 'feedbin', 'feedhq', 'feedly', 'fresh', 'inoreader', 'local', 'oldreader', 'owncloud', 'ttrss'],
+        value : ['bazqux', 'decsync', 'feedbin', 'feedhq', 'feedly', 'fresh', 'inoreader', 'local', 'oldreader', 'owncloud', 'ttrss'],
         description: 'List of backend plugins to install'
 )

plugins/backend/decsync/Rfc822.vala

@@ -0,0 +1,144 @@
+namespace FeedReader.Rfc822 {
+
+	/**
+	 * Parse a date string in RFC 822 format
+	 * Note that we don't use Time.strptime because it uses the current locale
+	 * to parse month names, but RFC 822 specifically requires months to be
+	 * written in English.
+     * See: https://www.w3.org/Protocols/rfc822/#z28
+	 * And: https://groups.yahoo.com/neo/groups/rss-public/conversations/topics/536
+	 * */
+	public static DateTime? parseDate(string? str)
+	{
+		if (str == null)
+			return null;
+
+		Regex re;
+		try {
+			re = new Regex("""
+				# We don't care about the day of the week
+				\s*(?:(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun),\s*)?
+				(?<day>\d{1,2})\s+
+				(?<month>Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\s+
+				# The standard specifies 2-digit years but 4 digit years are
+				# recommended now.
+				# This pattern will also accept 3-digit years, so we'll have to
+				# check for that separately
+				(?<year>\d{2,4})\s+
+				(?<hour>\d{2})
+				:(?<minute>\d{2})
+				(?::(?<second>\d{2}))?\s+
+				(?<zone>UT|GMT|EST|EDT|MST|MDT|PST|PDT|[A-Z]|(?:[+-]\d{4}))
+				""",
+				RegexCompileFlags.CASELESS | RegexCompileFlags.EXTENDED,
+				RegexMatchFlags.ANCHORED);
+		} catch (RegexError e) {
+			stderr.printf("RFC822 regex failed to parse: %s\n", e.message);
+			assert(false);
+			return null;
+		}
+
+		MatchInfo info;
+		if (!re.match(str, 0, out info))
+			return null;
+
+		var dayStr = info.fetch_named("day");
+		var day = int.parse(dayStr);
+
+		var monthStr = info.fetch_named("month").ascii_down();
+		int month;
+		switch(monthStr) {
+		case "jan":
+			month = 1;
+			break;
+		case "feb":
+			month = 2;
+			break;
+		case "mar":
+			month = 3;
+			break;
+		case "apr":
+			month = 4;
+			break;
+		case "may":
+			month = 5;
+			break;
+		case "jun":
+			month = 6;
+			break;
+		case "jul":
+			month = 7;
+			break;
+		case "aug":
+			month = 8;
+			break;
+		case "sep":
+			month = 9;
+			break;
+		case "oct":
+			month = 10;
+			break;
+		case "nov":
+			month = 11;
+			break;
+		case "dec":
+			month = 12;
+			break;
+		default:
+			// The regex should make this impossible
+			assert(false);
+			return null;
+		}
+
+		var yearStr = info.fetch_named("year");
+		var year = int.parse(yearStr);
+		// Two-digit years from 00 to 49 should be interpreted as 2000 to 2049
+		if (year >= 0 && year <= 49)
+			year += 2000;
+		// Two-digit years from 50 to 99 should be interpreted as 1950 to 1999
+		else if (year >= 50 && year < 100)
+			year += 1900;
+		var hourStr = info.fetch_named("hour");
+		var hour = int.parse(hourStr);
+		var minuteStr = info.fetch_named("minute");
+		var minute = int.parse(minuteStr);
+		var secondStr = info.fetch_named("second");
+		var second = secondStr == null || secondStr == "" ? 0 : int.parse(secondStr);
+
+		var zoneStr = info.fetch_named("zone");
+		TimeZone zone;
+		switch(zoneStr.ascii_up()) {
+			// Note sure if new TimeZone(zoneStr) would always work for these,
+			// so specifically handle the cases the spec requires
+			case "EDT":
+				zone = new TimeZone("-04");
+				break;
+			case "CDT":
+			case "EST":
+				zone = new TimeZone("-05");
+				break;
+			case "CST":
+			case "MDT":
+				zone = new TimeZone("-06");
+				break;
+			case "MST":
+			case "PDT":
+				zone = new TimeZone("-07");
+				break;
+			case "PST":
+				zone = new TimeZone("-08");
+				break;
+
+			case "GMT":
+			case "UT":
+			case "Z":
+				zone = new TimeZone.utc();
+				break;
+			default:
+				zone = new TimeZone(zoneStr);
+				break;
+		}
+
+		return new DateTime(zone, year, month, day, hour, minute, second);
+	}
+}

plugins/backend/decsync/decsync.gresource.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<gresources>
+	<gresource prefix="/org/gnome/FeedReader">
+		<file preprocess="xml-stripblanks">icons/64x64/places/feed-service-decsync.svg</file>
+		<file preprocess="xml-stripblanks">icons/64x64/places/feed-service-decsync-symbolic.svg</file>
+	</gresource>
+</gresources>

plugins/backend/decsync/decsync.plugin

@@ -0,0 +1,9 @@
+[Plugin]
+Module=decsync
+Loader=C
+Name=DecSync Backend
+Version=0.1
+Description=Adds a DecSync back-end to FeedReader. No RSS-service required.
+Authors=Jan Lukas Gernert <jangernert@gmail.com>, Aldo Gunsing <dev@aldogunsing.nl>
+Copyright=Copyright © 2015-16 Jan Lukas Gernert, Copyright © 2018 Aldo Gunsing
+Website=https://github.com/39aldo39/DecSync