import Contacts
import Foundation

/// Reads the system address book into `IPodContact` values.
///
/// An actor rather than a plain type so the non-`Sendable` `CNContactStore`
/// stays isolated, and so enumerating a large address book happens off the main
/// thread.
public actor ContactsReader {
    private let store = CNContactStore()

    public init() {}

    public nonisolated static var authorizationStatus: CNAuthorizationStatus {
        CNContactStore.authorizationStatus(for: .contacts)
    }

    /// Prompts for Contacts access, returning whether it was granted.
    public func requestAccess() async -> Bool {
        (try? await store.requestAccess(for: .contacts)) ?? false
    }

    /// The keys fetched for every contact.
    ///
    /// `CNContactNoteKey` is absent on purpose: since macOS 11 it requires the
    /// restricted `com.apple.developer.contacts.notes` entitlement, and asking
    /// for it without one makes the whole fetch throw.
    ///
    /// Computed rather than stored because `CNKeyDescriptor` is not `Sendable`,
    /// so a static constant would count as shared mutable state.
    private static var keysToFetch: [CNKeyDescriptor] {
        [
            CNContactIdentifierKey,
            CNContactNamePrefixKey,
            CNContactGivenNameKey,
            CNContactMiddleNameKey,
            CNContactFamilyNameKey,
            CNContactNameSuffixKey,
            CNContactOrganizationNameKey,
            CNContactJobTitleKey,
            CNContactPhoneNumbersKey,
            CNContactEmailAddressesKey,
            CNContactPostalAddressesKey,
            CNContactBirthdayKey,
        ] as [CNKeyDescriptor]
    }

    /// Every contact in every account, in the user's preferred sort order.
    public func fetchContacts() throws -> [IPodContact] {
        let request = CNContactFetchRequest(keysToFetch: Self.keysToFetch)
        request.sortOrder = .userDefault
        request.unifyResults = true

        var contacts: [IPodContact] = []
        try store.enumerateContacts(with: request) { contact, _ in
            contacts.append(Self.convert(contact))
        }
        return contacts
    }

    static func convert(_ contact: CNContact) -> IPodContact {
        IPodContact(
            id: contact.identifier,
            namePrefix: contact.namePrefix,
            givenName: contact.givenName,
            middleName: contact.middleName,
            familyName: contact.familyName,
            nameSuffix: contact.nameSuffix,
            organization: contact.organizationName,
            jobTitle: contact.jobTitle,
            phoneNumbers: contact.phoneNumbers.map {
                LabeledValue(
                    label: phoneType(for: $0.label),
                    value: $0.value.stringValue
                )
            },
            emailAddresses: contact.emailAddresses.map {
                LabeledValue(
                    label: emailType(for: $0.label),
                    value: $0.value as String
                )
            },
            postalAddresses: contact.postalAddresses.map {
                PostalAddress(
                    label: postalType(for: $0.label),
                    street: $0.value.street,
                    city: $0.value.city,
                    state: $0.value.state,
                    postalCode: $0.value.postalCode,
                    country: $0.value.country
                )
            },
            birthday: contact.birthday
        )
    }

    /// Maps a Contacts label to vCard 3.0 `TYPE` tokens.
    ///
    /// Only tokens vCard 3.0 actually defines are emitted — Contacts labels
    /// such as "Other" or a user's custom label have no equivalent, and an
    /// invented `TYPE` is another thing for the device's parser to trip on, so
    /// those fall back to a bare `VOICE`.
    static func phoneType(for label: String?) -> String {
        switch label {
        case CNLabelPhoneNumberMobile, CNLabelPhoneNumberiPhone: "CELL"
        case CNLabelHome: "HOME,VOICE"
        case CNLabelWork: "WORK,VOICE"
        case CNLabelPhoneNumberMain: "PREF,VOICE"
        case CNLabelPhoneNumberHomeFax: "HOME,FAX"
        case CNLabelPhoneNumberWorkFax, CNLabelPhoneNumberOtherFax: "WORK,FAX"
        case CNLabelPhoneNumberPager: "PAGER"
        default: "VOICE"
        }
    }

    /// Returns an empty label when there is no standard equivalent; the writer
    /// then emits `TYPE=INTERNET` alone.
    static func emailType(for label: String?) -> String {
        switch label {
        case CNLabelHome: "HOME"
        case CNLabelWork: "WORK"
        default: ""
        }
    }

    static func postalType(for label: String?) -> String {
        switch label {
        case CNLabelHome: "HOME"
        case CNLabelWork: "WORK"
        default: ""
        }
    }
}