import Foundation
import SwiftData

@Model
final class CelestiaSession {
    var id: UUID
    var title: String
    var startTime: Date
    var endTime: Date?
    var localAudioPath: String?
    var isSynced: Bool
    var cloudSessionId: String?
    var ownerUserID: String?
    // Defaults must live on the persisted properties so SwiftData can backfill
    // existing rows during a lightweight migration. Initializer defaults only
    // apply to newly-created model instances.
    var serverRevision: Int64 = 0
    var syncStateRaw: String = SessionSyncState.localOnly.rawValue
    var lastSyncError: String?
    var lastSyncedAt: Date?
    
    @Relationship(deleteRule: .cascade, inverse: \CelestiaTimelineEvent.session)
    var events: [CelestiaTimelineEvent]
    
    @Relationship(deleteRule: .cascade, inverse: \AudioChunk.session)
    var audioChunks: [AudioChunk]
    
    var durationMs: Int64 {
        guard let end = endTime else { return 0 }
        return Int64(end.timeIntervalSince(startTime) * 1000)
    }
    
    var durationFormatted: String {
        guard let end = endTime else { return "正在记录..." }
        let interval = end.timeIntervalSince(startTime)
        let hours = Int(interval) / 3600
        let minutes = (Int(interval) % 3600) / 60
        let seconds = Int(interval) % 60
        if hours > 0 {
            return String(format: "%d:%02d:%02d", hours, minutes, seconds)
        }
        return String(format: "%02d:%02d", minutes, seconds)
    }
    
    var photoCount: Int {
        events.filter { $0.eventType == "PHOTO" }.count
    }
    
    var noteCount: Int {
        events.filter {
            $0.eventType == "NOTE"
                || ($0.eventType == "MARKER" && !$0.isContinuationMarker)
        }.count
    }
    
    var syncState: SessionSyncState {
        get { SessionSyncState(rawValue: syncStateRaw) ?? .localOnly }
        set { syncStateRaw = newValue.rawValue }
    }

    /// A server-confirmed sync requires both the legacy completion flag and a
    /// remote identifier. This remains compatible with records created before
    /// `syncStateRaw` was added, whose migrated state defaults to `localOnly`.
    var hasConfirmedCloudSync: Bool {
        isSynced && cloudSessionId != nil
    }

    var needsCloudSync: Bool {
        !hasConfirmedCloudSync
    }

    func markContentModified() {
        isSynced = false
        syncState = .pending
        lastSyncError = nil
    }

    /// The revision represented by the current local content.
    /// Unsynced edits form the next revision based on the last known server revision.
    var localRevision: Int64 {
        if hasConfirmedCloudSync {
            return max(serverRevision, 1)
        }
        return max(serverRevision + 1, 1)
    }

    init(id: UUID = UUID(), title: String, localAudioPath: String? = nil, startTime: Date = Date()) {
        self.id = id
        self.title = title
        self.startTime = startTime
        self.endTime = nil
        self.localAudioPath = localAudioPath
        self.isSynced = false
        self.cloudSessionId = nil
        self.ownerUserID = nil
        self.serverRevision = 0
        self.syncStateRaw = SessionSyncState.localOnly.rawValue
        self.lastSyncError = nil
        self.lastSyncedAt = nil
        self.events = []
        self.audioChunks = []
    }
}

enum SessionSyncState: String, Codable {
    case localOnly
    case pending
    case syncing
    case synced
    case failed
    case conflict
}