KisaniCal/KisaniCal/Models/TaskItem.swift

import SwiftUI

// MARK: - Task Model
struct TaskItem: Identifiable, Codable, Equatable {
    var id = UUID()
    var title: String
    var dueDate: Date?
    var hasTime: Bool = false
    var isComplete: Bool = false
    var completedAt: Date? = nil
    var quadrant: Quadrant = .urgent
    var category: TaskCategory = .reminder
    var taskColor: TaskColor = .orange
    var isRecurring: Bool = false
    var isPinned: Bool = false
    var endDate: Date? = nil
    var isAllDay: Bool = false
}

enum Quadrant: String, CaseIterable, Identifiable, Codable {
    var id: String { rawValue }
    case urgent    = "Urgent + Important"
    case schedule  = "Schedule It"
    case delegate_ = "Delegate"
    case eliminate = "Eliminate"
}

enum TaskCategory: String, Codable {
    case reminder = "Reminder"
    case birthday = "Birthday"
    case domain   = "Domain"
    case annual   = "Annual"
    case custom   = "Custom"
}

enum TaskColor: String, Codable {
    case orange, green, blue, yellow

    func color() -> Color {
        switch self {
        case .orange: return AppColors.accent
        case .green:  return AppColors.green
        case .blue:   return AppColors.blue
        case .yellow: return AppColors.yellow
        }
    }
    func soft() -> Color {
        switch self {
        case .orange: return AppColors.accentSoft
        case .green:  return AppColors.greenSoft
        case .blue:   return AppColors.blueSoft
        case .yellow: return AppColors.yellowSoft
        }
    }
}

// MARK: - Task View Model
@MainActor
class TaskViewModel: ObservableObject {
    @Published var tasks: [TaskItem]

    private let persistKey: String

    init() {
        let uid = AuthManager.shared.currentUser?.id ?? "shared"
        self.persistKey = "kisani.tasks.v2.\(uid)"
        if let data = UserDefaults.standard.data(forKey: persistKey),
           let saved = try? JSONDecoder().decode([TaskItem].self, from: data), !saved.isEmpty {
            tasks = saved
        } else {
            tasks = []
        }
    }

    func reload() {
        guard let data  = UserDefaults.standard.data(forKey: persistKey),
              let saved = try? JSONDecoder().decode([TaskItem].self, from: data)
        else { return }
        tasks = saved
    }

    private func save() {
        if let data = try? JSONEncoder().encode(tasks) {
            UserDefaults.standard.set(data, forKey: persistKey)
        }
    }

    var overdueTasks: [TaskItem] {
        let startOfDay = Calendar.current.startOfDay(for: Date())
        return tasks.filter { !$0.isComplete && ($0.dueDate ?? .distantFuture) < startOfDay }
    }
    var todayTasks: [TaskItem] {
        let start = Calendar.current.startOfDay(for: Date())
        let end   = Calendar.current.date(byAdding: .day, value: 1, to: start)!
        return tasks
            .filter { !$0.isComplete && ($0.dueDate ?? .distantFuture) >= start && ($0.dueDate ?? .distantFuture) < end }
            .sorted { ($0.dueDate ?? .distantFuture) < ($1.dueDate ?? .distantFuture) }
    }
    var upcomingTasks: [TaskItem] {
        let cal = Calendar.current
        let fourDays = cal.date(byAdding: .day, value: 4, to: cal.startOfDay(for: Date()))!
        return tasks
            .filter { !$0.isComplete && ($0.dueDate ?? .distantFuture) >= fourDays }
            .sorted { ($0.dueDate ?? .distantFuture) < ($1.dueDate ?? .distantFuture) }
    }
    var next3DaysTasks: [(date: Date, tasks: [TaskItem])] {
        let cal = Calendar.current
        let today = cal.startOfDay(for: Date())
        return (1...3).compactMap { offset -> (Date, [TaskItem])? in
            guard let day = cal.date(byAdding: .day, value: offset, to: today),
                  let nextDay = cal.date(byAdding: .day, value: 1, to: day) else { return nil }
            let dayTasks = tasks.filter {
                !$0.isComplete &&
                ($0.dueDate ?? .distantFuture) >= day &&
                ($0.dueDate ?? .distantFuture) < nextDay
            }.sorted { ($0.dueDate ?? .distantFuture) < ($1.dueDate ?? .distantFuture) }
            return dayTasks.isEmpty ? nil : (day, dayTasks)
        }
    }
    var completedTodayTasks: [TaskItem] {
        let startOfDay = Calendar.current.startOfDay(for: Date())
        return tasks
            .filter { $0.isComplete && ($0.completedAt ?? .distantPast) >= startOfDay }
            .sorted { ($0.completedAt ?? .distantPast) > ($1.completedAt ?? .distantPast) }
    }

    func toggle(_ task: TaskItem) {
        guard let idx = tasks.firstIndex(where: { $0.id == task.id }) else { return }
        tasks[idx].isComplete.toggle()
        tasks[idx].completedAt = tasks[idx].isComplete ? Date() : nil
        save()
    }
    func tasks(for quadrant: Quadrant) -> [TaskItem] {
        tasks
            .filter { $0.quadrant == quadrant }
            .sorted { $0.isPinned && !$1.isPinned }
    }

    func pin(_ task: TaskItem) {
        guard let idx = tasks.firstIndex(where: { $0.id == task.id }) else { return }
        tasks[idx].isPinned.toggle()
        save()
    }

    func setDate(_ task: TaskItem, date: Date?) {
        guard let idx = tasks.firstIndex(where: { $0.id == task.id }) else { return }
        tasks[idx].dueDate = date
        save()
    }

    func setCategory(_ task: TaskItem, category: TaskCategory) {
        guard let idx = tasks.firstIndex(where: { $0.id == task.id }) else { return }
        tasks[idx].category = category
        save()
    }
    func moveToQuadrant(taskID: UUID, quadrant: Quadrant) {
        guard let idx = tasks.firstIndex(where: { $0.id == taskID }) else { return }
        tasks[idx].quadrant = quadrant
        save()
    }

    func addTask(title: String, dueDate: Date?, hasTime: Bool = false,
                 quadrant: Quadrant = .urgent, category: TaskCategory = .reminder,
                 taskColor: TaskColor = .orange, isRecurring: Bool = false,
                 endDate: Date? = nil, isAllDay: Bool = false) {
        tasks.append(TaskItem(title: title, dueDate: dueDate, hasTime: hasTime,
                              quadrant: quadrant, category: category,
                              taskColor: taskColor, isRecurring: isRecurring,
                              endDate: endDate, isAllDay: isAllDay))
        save()
    }

    func postpone(_ task: TaskItem, days: Int = 1) {
        guard let idx = tasks.firstIndex(where: { $0.id == task.id }) else { return }
        let base = tasks[idx].dueDate ?? Date()
        tasks[idx].dueDate = Calendar.current.date(byAdding: .day, value: days, to: base)
        save()
    }

    func postponeAllOverdue(days: Int = 1) {
        let ids = overdueTasks.map { $0.id }
        for id in ids {
            guard let idx = tasks.firstIndex(where: { $0.id == id }) else { continue }
            let base = tasks[idx].dueDate ?? Date()
            tasks[idx].dueDate = Calendar.current.date(byAdding: .day, value: days, to: base)
        }
        save()
    }

    func delete(_ task: TaskItem) {
        tasks.removeAll { $0.id == task.id }
        save()
    }
}