Add support for NIP-52 date-based and time-based calendar events

Sources/NostrSDK/EventCreating.swift

@@ -225,4 +225,110 @@ public extension EventCreating {
         ]
         return try ReportEvent(content: additionalInformation, tags: tags, signedBy: keypair)
     }
+
+    func dateBasedCalendarEvent(withName name: String, description: String = "", start: DateComponents, end: DateComponents? = nil, location: String? = nil, geohash: String? = nil, participants: [CalendarEventParticipant]? = nil, hashtags: [String]? = nil, references: [URL]? = nil, signedBy keypair: Keypair) throws -> DateBasedCalendarEventNostrEvent {
+
+        guard start.isValidDate(in: Calendar(identifier: .iso8601)) else {
+            throw EventCreatingError.invalidInput
+        }
+
+        guard end?.isValidDate(in: Calendar(identifier: .iso8601)) == true else {
+            throw EventCreatingError.invalidInput
+        }
+
+        guard let startDate = start.date else {
+            throw EventCreatingError.invalidInput
+        }
+
+        let endDate = end?.date
+        if endDate != nil {
+            guard let endDate, startDate < endDate else {
+                throw EventCreatingError.invalidInput
+            }
+        }
+
+        let iso8601DateFormatter = ISO8601DateFormatter()
+        iso8601DateFormatter.formatOptions = .withFullDate
+
+        var tags: [Tag] = [
+            Tag(name: .unknown("d"), value: UUID().uuidString),
+            Tag(name: .unknown("name"), value: name),
+            Tag(name: .unknown("start"), value: iso8601DateFormatter.string(from: startDate))
+        ]
+
+        if let endDate {
+            tags.append(Tag(name: .unknown("end"), value: iso8601DateFormatter.string(from: endDate)))
+        }
+
+        if let location {
+            tags.append(Tag(name: .unknown("location"), value: location))
+        }
+
+        if let geohash {
+            tags.append(Tag(name: .unknown("g"), value: geohash))
+        }
+
+        if let participants, !participants.isEmpty {
+            tags += participants.map { $0.tag }
+        }
+
+        if let hashtags, !hashtags.isEmpty {
+            tags += hashtags.map { Tag(name: .hashtag, value: $0) }
+        }
+
+        if let references, !references.isEmpty {
+            tags += references.map { Tag(name: .unknown("r"), value: $0.absoluteString) }
+        }
+
+        return try DateBasedCalendarEventNostrEvent(content: description, tags: tags, signedBy: keypair)
+    }
+
+    func timeBasedCalendarEvent(withName name: String, description: String = "", start: Date, end: Date? = nil, startTimeZone: TimeZone? = nil, endTimeZone: TimeZone? = nil, location: String? = nil, geohash: String? = nil, participants: [CalendarEventParticipant]? = nil, hashtags: [String]? = nil, references: [URL]? = nil, signedBy keypair: Keypair) throws -> TimeBasedCalendarEventNostrEvent {
+
+        if let end {
+            guard start < end else {
+                throw EventCreatingError.invalidInput
+            }
+        }
+
+        var tags: [Tag] = [
+            Tag(name: .unknown("d"), value: UUID().uuidString),
+            Tag(name: .unknown("name"), value: name),
+            Tag(name: .unknown("start"), value: String(Int64(start.timeIntervalSince1970)))
+        ]
+
+        if let end {
+            tags.append(Tag(name: .unknown("end"), value: String(Int64(end.timeIntervalSince1970))))
+        }
+
+        if let startTimeZone {
+            tags.append(Tag(name: .unknown("start_tzid"), value: startTimeZone.identifier))
+        }
+
+        if let endTimeZone {
+            tags.append(Tag(name: .unknown("end_tzid"), value: endTimeZone.identifier))
+        }
+
+        if let location {
+            tags.append(Tag(name: .unknown("location"), value: location))
+        }
+
+        if let geohash {
+            tags.append(Tag(name: .unknown("g"), value: geohash))
+        }
+
+        if let participants {
+            tags += participants.map { $0.tag }
+        }
+
+        if let hashtags {
+            tags += hashtags.map { Tag(name: .hashtag, value: $0) }
+        }
+
+        if let references {
+            tags += references.map { Tag(name: .unknown("r"), value: $0.absoluteString) }
+        }
+
+        return try TimeBasedCalendarEventNostrEvent(content: description, tags: tags, signedBy: keypair)
+    }
 }

Sources/NostrSDK/EventKind.swift

@@ -67,7 +67,11 @@ public enum EventKind: RawRepresentable, CaseIterable, Codable, Equatable {
     ///
     /// See [NIP-56](https://github.com/nostr-protocol/nips/blob/b4cdc1a73d415c79c35655fa02f5e55cd1f2a60c/56.md#nip-56).
     case report
-
+
+    case dateBasedCalendarEvent
+
+    case timeBasedCalendarEvent
+
     /// Any other event kind number that isn't supported by this enum yet will be represented by `unknown` so that `NostrEvent`s of those event kinds can still be encoded and decoded.
     case unknown(RawValue)
 
@@ -82,7 +86,9 @@ public enum EventKind: RawRepresentable, CaseIterable, Codable, Equatable {
         .repost,
         .reaction,
         .genericRepost,
-        .report
+        .report,
+        .dateBasedCalendarEvent,
+        .timeBasedCalendarEvent
     ]
 
     public init(rawValue: Int) {
@@ -102,6 +108,8 @@ public enum EventKind: RawRepresentable, CaseIterable, Codable, Equatable {
         case .reaction: return 7
         case .genericRepost: return 16
         case .report: return 1984
+        case .dateBasedCalendarEvent: return 31922
+        case .timeBasedCalendarEvent: return 31923
         case let .unknown(value): return value
         }
     }

Sources/NostrSDK/Events/Calendars/CalendarEventParticipant.swift

@@ -0,0 +1,69 @@
+//
+//  CalendarEventParticipant.swift
+//
+//
+//  Created by Terry Yiu on 11/15/23.
+//
+
+import Foundation
+
+public struct CalendarEventParticipant: PubkeyTag, RelayTagParameter, Equatable {
+    public static func == (lhs: Self, rhs: Self) -> Bool {
+        lhs.tag == rhs.tag
+    }
+
+    public let tag: Tag
+
+    public var pubkey: PublicKey? {
+        PublicKey(hex: tag.value)
+    }
+
+    public var relay: URL? {
+        guard !tag.otherParameters.isEmpty else {
+            return nil
+        }
+
+        let relayString = tag.otherParameters[0]
+        guard !relayString.isEmpty else {
+            return nil
+        }
+
+        let components = URLComponents(string: relayString)
+        guard components?.scheme == "wss" || components?.scheme == "ws" else {
+            return nil
+        }
+        return components?.url
+    }
+
+    public var role: String? {
+        guard tag.otherParameters.count >= 2 else {
+            return nil
+        }
+
+        return tag.otherParameters[1]
+    }
+
+    public init?(tag: Tag) {
+        guard tag.name == .pubkey else {
+            return nil
+        }
+
+        self.tag = tag
+    }
+
+    public init(pubkey: PublicKey, relay: URL? = nil, role: String? = nil) {
+        var otherParameters: [String] = [relay?.absoluteString ?? ""]
+        if let role, !role.isEmpty {
+            otherParameters.append(role)
+        }
+
+        tag = Tag(name: .pubkey, value: pubkey.hex, otherParameters: otherParameters)
+    }
+}
+
+public protocol CalendarEventParticipantInterpreting: NostrEvent {}
+public extension CalendarEventParticipantInterpreting {
+    var participants: [CalendarEventParticipant] {
+        tags.filter { $0.name == .pubkey }.compactMap { CalendarEventParticipant(tag: $0) }
+    }
+}

Sources/NostrSDK/Events/Calendars/DateBasedCalendarEventNostrEvent.swift

@@ -0,0 +1,62 @@
+//
+//  DateBasedCalendarEventNostrEvent.swift
+//
+//
+//  Created by Terry Yiu on 11/13/23.
+//
+
+import Foundation
+
+/// Date-based calendar event starts on a date and ends before a different date in the future.
+/// Its use is appropriate for all-day or multi-day events where time and time zone hold no significance. e.g., anniversary, public holidays, vacation days.
+/// See [NIP-52](https://github.com/nostr-protocol/nips/blob/master/52.md).
+public final class DateBasedCalendarEventNostrEvent: NostrEvent, CalendarEventParticipantInterpreting, HashtagInterpreting, ReferenceTagInterpreting {
+    public required init(from decoder: Decoder) throws {
+        try super.init(from: decoder)
+    }
+
+    @available(*, unavailable, message: "This initializer is unavailable for this class.")
+    override init(kind: EventKind, content: String, tags: [Tag] = [], createdAt: Int64 = Int64(Date.now.timeIntervalSince1970), signedBy keypair: Keypair) throws {
+        try super.init(kind: kind, content: content, tags: tags, createdAt: createdAt, signedBy: keypair)
+    }
+
+    public init(content: String, tags: [Tag] = [], createdAt: Int64 = Int64(Date.now.timeIntervalSince1970), signedBy keypair: Keypair) throws {
+        try super.init(kind: .dateBasedCalendarEvent, content: content, tags: tags, createdAt: createdAt, signedBy: keypair)
+    }
+
+    public var uuid: String? {
+        tags.first { $0.name.rawValue == "d" }?.value
+    }
+
+    public var name: String? {
+        tags.first { $0.name.rawValue == "name" }?.value
+    }
+
+    /// Start date represented by ``DateComponents`` in the calendar context of ``Calendar.Identifier.iso8601``, with `year`, `month`, and `day` populated.
+    /// `nil` is returned if the backing `start` tag is malformed.
+    public var start: DateComponents? {
+        guard let startString = tags.first(where: { $0.name.rawValue == "start" })?.value else {
+            return nil
+        }
+
+        return startString.dateStringAsDateComponents
+    }
+
+    /// End date represented by ``DateComponents`` in the calendar context of ``Calendar.Identifier.iso8601``, with `year`, `month`, and `day` populated.
+    /// `nil` is returned if the backing `end` tag is malformed.
+    public var end: DateComponents? {
+        guard let startString = tags.first(where: { $0.name.rawValue == "end" })?.value else {
+            return nil
+        }
+
+        return startString.dateStringAsDateComponents
+    }
+
+    public var location: String? {
+        tags.first { $0.name.rawValue == "location" }?.value
+    }
+
+    public var geohash: String? {
+        tags.first { $0.name.rawValue == "g" }?.value
+    }
+}

Sources/NostrSDK/Events/Calendars/TimeBasedCalendarEventNostrEvent.swift

@@ -0,0 +1,80 @@
+//
+//  TimeBasedCalendarEventEvent.swift
+//
+//
+//  Created by Terry Yiu on 11/16/23.
+//
+
+import Foundation
+
+/// Time-based calendar event spans between a start time and end time.
+///
+/// Unlike the term `calendar event` specific to NIP-52, the term `event` is used broadly in all the NIPs to describe any Nostr event.
+/// That is the reason why the word `event` appears twice. It is not a typo.
+public final class TimeBasedCalendarEventNostrEvent: NostrEvent, CalendarEventParticipantInterpreting, HashtagInterpreting, ReferenceTagInterpreting {
+    public required init(from decoder: Decoder) throws {
+        try super.init(from: decoder)
+    }
+
+    @available(*, unavailable, message: "This initializer is unavailable for this class.")
+    override init(kind: EventKind, content: String, tags: [Tag] = [], createdAt: Int64 = Int64(Date.now.timeIntervalSince1970), signedBy keypair: Keypair) throws {
+        try super.init(kind: kind, content: content, tags: tags, createdAt: createdAt, signedBy: keypair)
+    }
+
+    public init(content: String, tags: [Tag] = [], createdAt: Int64 = Int64(Date.now.timeIntervalSince1970), signedBy keypair: Keypair) throws {
+        try super.init(kind: .timeBasedCalendarEvent, content: content, tags: tags, createdAt: createdAt, signedBy: keypair)
+    }
+
+    public var uuid: String? {
+        tags.first { $0.name.rawValue == "d" }?.value
+    }
+
+    public var name: String? {
+        tags.first { $0.name.rawValue == "name" }?.value
+    }
+
+    /// Start timestamp of calendar event represented by ``Date``.
+    /// `nil` is returned if the backing `start` tag is malformed.
+    public var start: Date? {
+        guard let startString = tags.first(where: { $0.name.rawValue == "start" })?.value, let startSeconds = Int(startString) else {
+            return nil
+        }
+
+        return Date(timeIntervalSince1970: TimeInterval(startSeconds))
+    }
+
+    /// End timestamp represented by ``Date``.
+    /// `nil` is returned if the backing `end` tag is malformed.
+    public var end: Date? {
+        guard let endString = tags.first(where: { $0.name.rawValue == "end" })?.value, let endSeconds = Int(endString) else {
+            return nil
+        }
+
+        return Date(timeIntervalSince1970: TimeInterval(endSeconds))
+    }
+
+    public var startTimeZone: TimeZone? {
+        guard let timeZoneIdentifier = tags.first(where: { $0.name.rawValue == "start_tzid" })?.value else {
+            return nil
+        }
+
+        return TimeZone(identifier: timeZoneIdentifier)
+    }
+
+    public var endTimeZone: TimeZone? {
+        guard let timeZoneIdentifier = tags.first(where: { $0.name.rawValue == "end_tzid" })?.value else {
+            return nil
+        }
+
+        return TimeZone(identifier: timeZoneIdentifier)
+    }
+
+    public var location: String? {
+        tags.first { $0.name.rawValue == "location" }?.value
+    }
+
+    public var geohash: String? {
+        tags.first { $0.name.rawValue == "g" }?.value
+    }
+}
+

Sources/NostrSDK/Events/Tags/HashtagInterpreting.swift

@@ -0,0 +1,16 @@
+//
+//  HashtagInterpreting.swift
+//
+//
+//  Created by Terry Yiu on 11/15/23.
+//
+
+import Foundation
+
+public protocol HashtagInterpreting: NostrEvent {}
+public extension HashtagInterpreting {
+    var hashtags: [String] {
+        tags.filter { $0.name == .hashtag }
+            .map { $0.value }
+    }
+}

Sources/NostrSDK/Events/Tags/PubkeyTag.swift

@@ -0,0 +1,12 @@
+//
+//  PubkeyTag.swift
+//  
+//
+//  Created by Terry Yiu on 11/15/23.
+//
+
+import Foundation
+
+public protocol PubkeyTag {
+    var pubkey: PublicKey? { get }
+}