import Foundation
import Testing
@testable import LocalData

private struct LegacyStringKey: StorageKey {
    typealias Value = String
    let name: String
    let domain: StorageDomain
    let security: SecurityPolicy = .none
    let serializer: Serializer<String> = .json
    let owner: String = "Legacy"
    let description: String = "Legacy key"
    let availability: PlatformAvailability = .all
    let syncPolicy: SyncPolicy = .never
}

private struct DestinationStringKey: StorageKey {
    typealias Value = String
    let name: String
    let domain: StorageDomain
    let security: SecurityPolicy = .keychain(accessibility: .afterFirstUnlock, accessControl: .none)
    let serializer: Serializer<String> = .json
    let owner: String = "Destination"
    let description: String = "Destination key"
    let availability: PlatformAvailability = .all
    let syncPolicy: SyncPolicy = .never
}

private struct SourceStringKey: StorageKey {
    typealias Value = String
    let name: String
    let domain: StorageDomain
    let security: SecurityPolicy = .none
    let serializer: Serializer<String> = .json
    let owner: String = "Source"
    let description: String = "Source key"
    let availability: PlatformAvailability = .all
    let syncPolicy: SyncPolicy = .never
}

private struct DestinationIntKey: StorageKey {
    typealias Value = Int
    let name: String
    let domain: StorageDomain
    let security: SecurityPolicy = .none
    let serializer: Serializer<Int> = .json
    let owner: String = "Destination"
    let description: String = "Destination int key"
    let availability: PlatformAvailability = .all
    let syncPolicy: SyncPolicy = .never
}

@Suite(.serialized)
struct MigrationProtocolTests {
    private let router: StorageRouter

    init() {
        let testBaseURL = FileManager.default.temporaryDirectory.appending(path: "MigrationProtocolTests-\(UUID().uuidString)")
        router = StorageRouter(
            keychain: MockKeychainHelper(),
            encryption: EncryptionHelper(keychain: MockKeychainHelper()),
            file: FileStorageHelper(configuration: FileStorageConfiguration(baseURL: testBaseURL)),
            defaults: UserDefaultsHelper(defaults: UserDefaults(suiteName: "MigrationProtocolTests.\(UUID().uuidString)")!)
        )
    }

    @Test func simpleLegacyMigrationTest() async throws {
        let legacyKey = LegacyStringKey(name: "legacy.simple", domain: .userDefaults(suite: nil))
        let destinationKey = DestinationStringKey(name: "modern.simple", domain: .keychain(service: "test.migration"))
        try await router.set("value", for: legacyKey)

        let migration = SimpleLegacyMigration(destinationKey: destinationKey, sourceKey: .key(legacyKey))
        let context = MigrationContext(appVersion: "1.0")

        let shouldMigrate = try await migration.shouldMigrate(using: router, context: context)
        #expect(shouldMigrate == true)

        let result = try await migration.migrate(using: router, context: context)
        #expect(result.success == true)

        let migratedValue = try await router.get(destinationKey)
        #expect(migratedValue == "value")
    }

    @Test func conditionalMigrationTest() async throws {
        let legacyKey = LegacyStringKey(name: "legacy.conditional", domain: .userDefaults(suite: nil))
        let destinationKey = DestinationStringKey(name: "modern.conditional", domain: .keychain(service: "test.migration"))
        try await router.set("value", for: legacyKey)

        let fallback = AnyStorageMigration(
            SimpleLegacyMigration(destinationKey: destinationKey, sourceKey: .key(legacyKey))
        )
        let migration = AppVersionConditionalMigration(
            destinationKey: destinationKey,
            minAppVersion: "2.0",
            fallbackMigration: fallback
        )

        let context = MigrationContext(appVersion: "1.0")
        let shouldMigrate = try await migration.shouldMigrate(using: router, context: context)
        #expect(shouldMigrate == true)

        let result = try await migration.migrate(using: router, context: context)
        #expect(result.success == true)
    }

    @Test func transformingMigrationTest() async throws {
        let sourceKey = SourceStringKey(name: "legacy.transform", domain: .userDefaults(suite: nil))
        let destinationKey = DestinationIntKey(name: "modern.transform", domain: .userDefaults(suite: nil))
        try await router.set("42", for: sourceKey)

        let migration = DefaultTransformingMigration(
            destinationKey: destinationKey,
            sourceKey: sourceKey
        ) { value in
            guard let intValue = Int(value) else {
                throw MigrationError.transformationFailed("Invalid integer")
            }
            return intValue
        }

        let result = try await migration.migrate(using: router, context: MigrationContext())
        #expect(result.success == true)

        let migratedValue = try await router.get(destinationKey)
        #expect(migratedValue == 42)
    }

    @Test func aggregatingMigrationTest() async throws {
        let sourceKeyA = SourceStringKey(name: "legacy.aggregate.a", domain: .userDefaults(suite: nil))
        let sourceKeyB = SourceStringKey(name: "legacy.aggregate.b", domain: .userDefaults(suite: nil))
        let destinationKey = DestinationStringKey(name: "modern.aggregate", domain: .userDefaults(suite: nil))

        try await router.set("alpha", for: sourceKeyA)
        try await router.set("beta", for: sourceKeyB)

        let migration = DefaultAggregatingMigration(
            destinationKey: destinationKey,
            sourceKeys: [.key(sourceKeyA), .key(sourceKeyB)]
        ) { sources in
            let values = sources.compactMap { $0.value as? String }
            return values.joined(separator: ",")
        }

        let result = try await migration.migrate(using: router, context: MigrationContext())
        #expect(result.success == true)

        let migratedValue = try await router.get(destinationKey)
        #expect(migratedValue.contains("alpha"))
        #expect(migratedValue.contains("beta"))
    }

    @Test func migrationErrorHandlingTest() async throws {
        let destinationKey = DestinationStringKey(name: "modern.error", domain: .userDefaults(suite: nil))
        let migration = FailingMigration(destinationKey: destinationKey, error: .transformationFailed("Failed"))
        let result = try await migration.migrate(using: router, context: MigrationContext())

        #expect(result.success == false)
        #expect(result.errors.first == .transformationFailed("Failed"))
    }
}