//
//  TravelOverrideService.swift
//  SportsTime
//
//  CloudKit service for travel day position overrides
//

import Foundation
import CloudKit

actor TravelOverrideService {
    static let shared = TravelOverrideService()

    private let container: CKContainer
    private let publicDatabase: CKDatabase

    private init() {
        self.container = CKContainer(identifier: "iCloud.com.sportstime.app")
        self.publicDatabase = container.publicCloudDatabase
    }

    // MARK: - CRUD Operations

    /// Create or update a travel day override (upserts by tripId + travelAnchorId)
    func saveOverride(_ override: TravelDayOverride) async throws -> TravelDayOverride {
        print("☁️ [CloudKit] Saving travel override for: \(override.travelAnchorId)")

        // Look up existing override by travelAnchorId (not by UUID)
        let existingOverrides = try await fetchOverrides(forTripId: override.tripId)
        let existingOverride = existingOverrides.first { $0.travelAnchorId == override.travelAnchorId }

        let record: CKRecord
        let now = Date()

        if let existing = existingOverride {
            // Fetch the actual CKRecord to update it
            let recordID = CKRecord.ID(recordName: existing.id.uuidString)
            do {
                let existingRecord = try await publicDatabase.record(for: recordID)
                existingRecord[CKTravelDayOverride.displayDayKey] = override.displayDay
                existingRecord[CKTravelDayOverride.modifiedAtKey] = now
                record = existingRecord
                print("☁️ [CloudKit] Updating existing override record: \(existing.id)")
            } catch {
                // Record doesn't exist anymore, create new
                let ckOverride = CKTravelDayOverride(override: override)
                record = ckOverride.record
            }
        } else {
            // Create new record
            let ckOverride = CKTravelDayOverride(override: override)
            record = ckOverride.record
            print("☁️ [CloudKit] Creating new override record")
        }

        do {
            try await publicDatabase.save(record)
            print("☁️ [CloudKit] Travel override saved: \(record.recordID.recordName)")
            var savedOverride = override
            savedOverride.modifiedAt = now
            return savedOverride
        } catch let error as CKError {
            print("☁️ [CloudKit] CKError on save: \(error.code.rawValue) - \(error.localizedDescription)")
            throw mapCloudKitError(error)
        } catch {
            print("☁️ [CloudKit] Unknown error on save: \(error)")
            throw TravelOverrideError.unknown(error)
        }
    }

    /// Delete a travel day override
    func deleteOverride(_ overrideId: UUID) async throws {
        let recordID = CKRecord.ID(recordName: overrideId.uuidString)

        do {
            try await publicDatabase.deleteRecord(withID: recordID)
            print("☁️ [CloudKit] Travel override deleted: \(overrideId)")
        } catch let error as CKError {
            if error.code != .unknownItem {
                throw mapCloudKitError(error)
            }
            // Already deleted - ignore
        } catch {
            throw TravelOverrideError.unknown(error)
        }
    }

    /// Delete override by travel anchor ID (useful when removing by travel segment)
    func deleteOverride(forTripId tripId: UUID, travelAnchorId: String) async throws {
        // First fetch to find the record
        let overrides = try await fetchOverrides(forTripId: tripId)
        if let existing = overrides.first(where: { $0.travelAnchorId == travelAnchorId }) {
            try await deleteOverride(existing.id)
        }
    }

    /// Fetch all travel day overrides for a trip
    func fetchOverrides(forTripId tripId: UUID) async throws -> [TravelDayOverride] {
        print("☁️ [CloudKit] Fetching travel overrides for tripId: \(tripId.uuidString)")
        let predicate = NSPredicate(
            format: "%K == %@",
            CKTravelDayOverride.tripIdKey,
            tripId.uuidString
        )
        let query = CKQuery(recordType: CKRecordType.travelDayOverride, predicate: predicate)

        do {
            let (results, _) = try await publicDatabase.records(matching: query)
            print("☁️ [CloudKit] Query returned \(results.count) travel override records")

            let overrides = results.compactMap { result -> TravelDayOverride? in
                guard case .success(let record) = result.1 else {
                    print("☁️ [CloudKit] Record fetch failed for: \(result.0.recordName)")
                    return nil
                }
                let override = CKTravelDayOverride(record: record).toOverride()
                if override == nil {
                    print("☁️ [CloudKit] Failed to parse travel override record: \(record.recordID.recordName)")
                }
                return override
            }

            print("☁️ [CloudKit] Parsed \(overrides.count) valid travel overrides")
            return overrides
        } catch let error as CKError {
            print("☁️ [CloudKit] CKError on fetch: \(error.code.rawValue) - \(error.localizedDescription)")
            throw mapCloudKitError(error)
        } catch {
            print("☁️ [CloudKit] Unknown error on fetch: \(error)")
            throw TravelOverrideError.unknown(error)
        }
    }

    /// Convert array of overrides to dictionary keyed by travelAnchorId
    /// If duplicate travelAnchorIds exist (legacy data), takes the most recently modified one
    func fetchOverridesAsDictionary(forTripId tripId: UUID) async throws -> [String: Int] {
        let overrides = try await fetchOverrides(forTripId: tripId)
        // Sort by modifiedAt descending so most recent comes first
        let sorted = overrides.sorted { $0.modifiedAt > $1.modifiedAt }
        // Use uniquingKeysWith to keep the first (most recent) value for duplicates
        return Dictionary(sorted.map { ($0.travelAnchorId, $0.displayDay) }) { first, _ in first }
    }

    // MARK: - Error Mapping

    private func mapCloudKitError(_ error: CKError) -> TravelOverrideError {
        switch error.code {
        case .notAuthenticated:
            return .notSignedIn
        case .networkUnavailable, .networkFailure:
            return .networkUnavailable
        case .unknownItem:
            return .overrideNotFound
        default:
            return .unknown(error)
        }
    }
}

// MARK: - Errors

enum TravelOverrideError: Error, LocalizedError {
    case notSignedIn
    case overrideNotFound
    case networkUnavailable
    case unknown(Error)

    var errorDescription: String? {
        switch self {
        case .notSignedIn:
            return "Please sign in to iCloud to customize travel days."
        case .overrideNotFound:
            return "Travel day setting not found."
        case .networkUnavailable:
            return "Unable to connect. Please check your internet connection."
        case .unknown(let error):
            return "An error occurred: \(error.localizedDescription)"
        }
    }
}