Support weekday variation

Sources/JavaScriptBridge.swift

@@ -118,7 +118,7 @@ internal extension RecurrenceRule {
         }
 
         let byweekdayJSSymbols = byweekday.map({ (weekday) -> String in
-            return weekday.toJSONSymbol()
+          return weekday.1.toJSONSymbol()
         })
         if byweekdayJSSymbols.count > 0 {
             jsonString += "byweekday: [\(byweekdayJSSymbols.joined(separator: ","))],"

Sources/RRule.swift

@@ -44,7 +44,6 @@ public class RRule: NSObject {
 
     let recurrenceRule = RecurrenceRule(frequency: .daily)
     var ruleFrequency: RecurrenceFrequency?
-    var byDayValue = ""
     for rule in rules {
       let ruleComponents = rule.components(separatedBy: "=")
       guard ruleComponents.count == 2 else {
@@ -145,11 +144,15 @@ public class RRule: NSObject {
       if ruleName == "BYDAY" {
         // These variables will define the weekdays where the recurrence will be applied.
         // In the RFC documentation, it is specified as BYDAY, but was renamed to avoid the ambiguity of that argument.
-        let byweekday = ruleValue.components(separatedBy: ",").compactMap({ (string) -> EKWeekday? in
-          byDayValue = string
-          return EKWeekday.weekdayFromSymbol(string)
+        let byweekday = ruleValue.components(separatedBy: ",").compactMap({ (string) -> (Int?, EKWeekday)? in
+          guard let parsedSymbol = EKWeekday.weekdayFromSymbol(String(string.suffix(2))) else { return nil }
+          let specific = Int(string.prefix(string.count - 2))
+          if let position = specific { recurrenceRule.bysetpos = [position] }
+          return (specific, parsedSymbol)
+        })
+        recurrenceRule.byweekday = byweekday.sorted(by: { (a, b) -> Bool in
+          return a.1 < b.1
         })
-        recurrenceRule.byweekday = byweekday.sorted(by: <)
       }
 
       if ruleName == "BYHOUR" {
@@ -179,22 +182,6 @@ public class RRule: NSObject {
       return nil
     }
     recurrenceRule.frequency = frequency
-    guard recurrenceRule.frequency == .monthly &&
-            recurrenceRule.bymonthday.isEmpty &&
-            recurrenceRule.bysetpos.isEmpty &&
-            !byDayValue.isEmpty
-    else { return recurrenceRule }
-
-    let offsetString = byDayValue.components(separatedBy: CharacterSet.decimalDigits.inverted).joined()
-    if offsetString.isEmpty {
-      return recurrenceRule
-    }
-    var offset = Int(offsetString)!
-    if byDayValue.starts(with: "-") {
-      offset = -1 * offset
-    }
-    recurrenceRule.bysetpos = [offset]
-    recurrenceRule.byweekday = [EKWeekday.weekdayFromSymbol(String(byDayValue.suffix(2)))!]
     return recurrenceRule
   }
 
@@ -262,11 +249,12 @@ public class RRule: NSObject {
       rruleString += "BYMONTHDAY=\(bymonthdayStrings.joined(separator: ","));"
     }
 
-    let byweekdaySymbols = rule.byweekday.map({ (weekday) -> String in
-      return weekday.toSymbol()
-    })
-    if byweekdaySymbols.count > 0 {
-      rruleString += "BYDAY=\(byweekdaySymbols.joined(separator: ","));"
+    let byweekdayElements = rule.byweekday.map { weekdayTuple -> String in
+      let position = rule.bysetpos.map { String($0) }
+      return "\(position)\(weekdayTuple.1.toSymbol())"
+    }
+    if byweekdayElements.count > 0 {
+      rruleString += "BYDAY=\(byweekdayElements.joined(separator: ","));"
     }
 
     let byhourStrings = rule.byhour.map({ (hour) -> String in

Sources/RecurrenceRule.swift

@@ -61,7 +61,7 @@ public class RecurrenceRule: NSObject {
     public var bymonthday = [Int]()
 
     /// The days of the week associated with the recurrence rule, as an array of EKWeekday objects.
-    public var byweekday = [EKWeekday]()
+    public var byweekday = [(Int?, EKWeekday)]()
 
     /// The hours of the day associated with the recurrence rule, as an array of integers.
     public var byhour = [Int]()