KisaniCal/KisaniCalWidgets/EventCountdownWidget.swift

import WidgetKit
import SwiftUI
import AppIntents

// MARK: - Configuration Intent
//
// Each widget instance stores its own event. The user sets a name, the day the
// countdown starts ("Counting from" — defaults to the day they add the widget,
// which acts as the creation anchor) and the event date. Because these values are
// persisted per-instance by WidgetKit, the widget is fully self-contained and does
// not depend on App Group data sharing.

struct EventConfigIntent: WidgetConfigurationIntent {
    static var title: LocalizedStringResource = "Event Countdown"
    static var description = IntentDescription("Count down to any upcoming event with a dot grid.")

    // Pick one of your existing events (tasks with a due date). When set, it
    // overrides the manual name/date fields below.
    @Parameter(title: "Track event")
    var event: EventEntity?

    @Parameter(title: "Or event name", default: "My Event")
    var eventName: String

    @Parameter(title: "Event date", default: Date.now)
    var targetDate: Date

    @Parameter(title: "Counting from", default: Date.now)
    var startDate: Date
}

// MARK: - Event picker (reads your tasks from the App Group)

struct EventEntity: AppEntity {
    let id: String          // task UUID string
    let title: String
    let dueDate: Date?

    static var typeDisplayRepresentation: TypeDisplayRepresentation = "Event"
    static var defaultQuery = EventQuery()

    var displayRepresentation: DisplayRepresentation {
        if let d = dueDate {
            let f = DateFormatter(); f.dateStyle = .medium
            return DisplayRepresentation(title: "\(title)", subtitle: "\(f.string(from: d))")
        }
        return DisplayRepresentation(title: "\(title)")
    }
}

struct EventQuery: EntityQuery {
    func entities(for identifiers: [String]) async throws -> [EventEntity] {
        allEvents().filter { identifiers.contains($0.id) }
    }

    func suggestedEntities() async throws -> [EventEntity] {
        allEvents()
    }

    private func allEvents() -> [EventEntity] {
        loadWidgetTasks()
            .filter { !$0.isComplete && $0.dueDate != nil }
            .sorted { ($0.dueDate ?? .distantFuture) < ($1.dueDate ?? .distantFuture) }
            .map { EventEntity(id: $0.id.uuidString, title: $0.title, dueDate: $0.dueDate) }
    }
}

// MARK: - Entry

struct EventEntry: TimelineEntry {
    let date: Date
    let eventName: String
    let start: Date
    let target: Date

    /// Fraction of the countdown window that has elapsed (0…1).
    var progress: Double {
        let span = target.timeIntervalSince(start)
        guard span > 0 else { return target <= date ? 1 : 0 }
        return min(1, max(0, date.timeIntervalSince(start) / span))
    }

    /// Whole days from start to target (the number of dots in the grid).
    var totalDays: Int {
        let cal = Calendar.current
        let d = cal.dateComponents([.day],
                                   from: cal.startOfDay(for: start),
                                   to: cal.startOfDay(for: target)).day ?? 0
        return max(1, d)
    }

    /// Days remaining until the event (never negative).
    var daysLeft: Int {
        let cal = Calendar.current
        let d = cal.dateComponents([.day],
                                   from: cal.startOfDay(for: date),
                                   to: cal.startOfDay(for: target)).day ?? 0
        return max(0, d)
    }
}

// MARK: - Provider

struct EventProvider: AppIntentTimelineProvider {
    func placeholder(in context: Context) -> EventEntry {
        EventEntry(date: .now,
                   eventName: "Mum's Birthday",
                   start: Date().addingTimeInterval(-86400 * 320),
                   target: Date().addingTimeInterval(86400 * 60))
    }

    func snapshot(for configuration: EventConfigIntent, in context: Context) async -> EventEntry {
        entry(for: configuration)
    }

    func timeline(for configuration: EventConfigIntent, in context: Context) async -> Timeline<EventEntry> {
        let entry = entry(for: configuration)
        // Recompute at the next midnight so the grid advances one dot per day.
        let nextMidnight = Calendar.current.startOfDay(for: Date().addingTimeInterval(86400))
        return Timeline(entries: [entry], policy: .after(nextMidnight))
    }

    private func entry(for config: EventConfigIntent) -> EventEntry {
        let name: String
        let target: Date
        if let ev = config.event, let due = ev.dueDate {
            // A picked event supplies its own name + date.
            name = ev.title
            target = due
        } else {
            name = config.eventName.isEmpty ? "My Event" : config.eventName
            target = config.targetDate
        }
        // Never let the start sit after the target.
        let start = min(config.startDate, target)
        return EventEntry(date: .now, eventName: name, start: start, target: target)
    }
}

// MARK: - Widget

struct EventCountdownWidget: Widget {
    let kind = "KisaniEventCountdown"

    var body: some WidgetConfiguration {
        AppIntentConfiguration(kind: kind, intent: EventConfigIntent.self, provider: EventProvider()) { entry in
            EventCountdownView(entry: entry)
        }
        .configurationDisplayName("Event Countdown")
        .description("Track the days until any upcoming event with a dot grid.")
        .supportedFamilies([.systemMedium, .systemSmall])
    }
}