//
//  WatchSyncManager.swift
//  Haru_Danim
//
//  Apple Watch 실시간 연동 (CLAUDE.md §9.1)
//  - 워치의 실행 명령을 받아 DB에 반영하고 최신 스냅숏을 돌려준다
//  - 데이터가 바뀔 때마다 updateApplicationContext로 최신 상태를 밀어 넣는다
//

import Foundation
import SwiftData
import WatchConnectivity
import WidgetKit

@MainActor
final class WatchSyncManager: NSObject {
    static let shared = WatchSyncManager()

    func activate() {
        guard WCSession.isSupported() else { return }
        let session = WCSession.default
        session.delegate = self
        session.activate()
    }

    // MARK: 스냅숏 생성

    /// 현재 DB 상태로 워치용 스냅숏 생성
    func makeSnapshot() -> WatchSnapshot {
        let context = DataStore.shared.mainContext
        let now = Date.now
        let math = DayMath()
        let agg = Aggregator(math: math)

        var snapshot = WatchSnapshot()
        snapshot.isPremium = PremiumGate.isUnlocked(.watchApp)

        let tags = (try? context.fetch(FetchDescriptor<Tag>(
            sortBy: [SortDescriptor(\.sortOrder), SortDescriptor(\.createdAt)]
        ))) ?? []
        snapshot.tags = tags.map { WatchTagInfo(id: $0.uuid, name: $0.name, colorHex: $0.colorHex) }

        let actions = (try? context.fetch(FetchDescriptor<Action>(sortBy: [SortDescriptor(\.sortOrder)]))) ?? []
        snapshot.actions = actions.map { action in
            let todayValue = agg.todayValue(for: action, now: now)
            let isCount = action.trackingType == .count
            return WatchActionInfo(
                id: action.uuid,
                name: action.name,
                symbolName: action.symbolName,
                colorHex: action.sortedTags.first?.colorHex ?? "#2F6B4F",
                isCount: isCount,
                todayValue: todayValue,
                isRunning: action.isRunning,
                tickingBase: action.isRunning && !isCount ? now.addingTimeInterval(-todayValue) : nil,
                tagIDs: action.sortedTags.map(\.uuid)
            )
        }

        let goals = (try? context.fetch(FetchDescriptor<Goal>(
            predicate: #Predicate { $0.statusRaw == "inProgress" },
            sortBy: [SortDescriptor(\.sortOrder), SortDescriptor(\.createdAt)]
        ))) ?? []
        snapshot.goals = goals.map { goal in
            WatchGoalInfo(
                id: goal.uuid,
                title: goal.title,
                symbolName: goal.symbolName,
                colorHex: goal.colorHex,
                dayRatio: goal.combinedSpanRatio(.day, math: math, now: now),
                weekRatio: goal.combinedSpanRatio(.week, math: math, now: now),
                monthRatio: goal.combinedSpanRatio(.month, math: math, now: now),
                quests: goal.sortedQuests.map { quest in
                    let progress = QuestProgress(quest: quest, math: math)
                    let day = progress.spanProgress(.day, now: now)
                    let week = progress.spanProgress(.week, now: now)
                    let month = progress.spanProgress(.month, now: now)
                    return WatchQuestInfo(
                        id: quest.uuid,
                        name: quest.targetName,
                        symbolName: quest.targetSymbol,
                        colorHex: quest.targetAction?.sortedTags.first?.colorHex
                            ?? quest.targetTag?.colorHex ?? "#2F6B4F",
                        dayRatio: day.ratio,
                        weekRatio: week.ratio,
                        monthRatio: month.ratio,
                        isAtMost: quest.direction == .atMost,
                        dayAchieved: day.isAchieved,
                        weekAchieved: week.isAchieved,
                        monthAchieved: month.isAchieved
                    )
                }
            )
        }

        // 현재 측정 중 대표 행동 (다이나믹 아일랜드와 동일 기준)
        let running = (try? context.fetch(FetchDescriptor<TimeSession>(
            predicate: #Predicate { $0.endAt == nil },
            sortBy: [SortDescriptor(\.startAt, order: .forward)]
        ))) ?? []
        let mode = LiveActivityMode(
            rawValue: AppGroup.defaults.string(forKey: SettingsKeys.liveActivityMode)
                ?? UserDefaults.standard.string(forKey: SettingsKeys.liveActivityMode) ?? ""
        ) ?? .latest
        if let representative = mode == .earliest ? running.first : running.last,
           let action = representative.action {
            snapshot.runningName = action.name
            snapshot.runningSymbol = action.symbolName
            snapshot.runningStartAt = representative.startAt
            snapshot.extraRunningCount = max(0, running.count - 1)
        }

        return snapshot
    }

    /// 최신 스냅숏을 워치로 전송 (데이터 변경 시마다 호출)
    func pushSnapshot() {
        guard WCSession.isSupported() else { return }
        let session = WCSession.default
        guard session.activationState == .activated, session.isPaired, session.isWatchAppInstalled else { return }
        guard let data = makeSnapshot().encoded() else { return }
        try? session.updateApplicationContext([WatchSync.snapshotKey: data])
    }

    // MARK: 명령 처리

    /// 워치의 명령을 처리하고 최신 스냅숏 응답을 만든다
    fileprivate func handle(command: String?, actionID: String?) -> [String: Any] {
        let context = DataStore.shared.mainContext
        if command == WatchSync.runCommand,
           let idString = actionID,
           let id = UUID(uuidString: idString),
           PremiumGate.isUnlocked(.watchApp) {
            let actions = (try? context.fetch(FetchDescriptor<Action>())) ?? []
            if let action = actions.first(where: { $0.uuid == id }) {
                ActionRunner.run(action, context: context)
                try? context.save()
                LiveActivityManager.sync(context: context)
                WidgetCenter.shared.reloadAllTimelines()
            }
        }
        guard let data = makeSnapshot().encoded() else { return [:] }
        return [WatchSync.snapshotKey: data]
    }
}

extension WatchSyncManager: WCSessionDelegate {
    nonisolated func session(
        _ session: WCSession,
        activationDidCompleteWith activationState: WCSessionActivationState,
        error: (any Error)?
    ) {
        Task { @MainActor in
            WatchSyncManager.shared.pushSnapshot()
        }
    }

    nonisolated func sessionDidBecomeInactive(_ session: WCSession) {}

    nonisolated func sessionDidDeactivate(_ session: WCSession) {
        session.activate()
    }

    /// 워치의 실행/새로 고침 요청 (응답으로 최신 스냅숏 반환)
    nonisolated func session(
        _ session: WCSession,
        didReceiveMessage message: [String: Any],
        replyHandler: @escaping ([String: Any]) -> Void
    ) {
        let command = message[WatchSync.commandKey] as? String
        let actionID = message[WatchSync.actionIDKey] as? String
        Task { @MainActor in
            let reply = WatchSyncManager.shared.handle(command: command, actionID: actionID)
            replyHandler(reply)
            WatchSyncManager.shared.pushSnapshot()
        }
    }
}