import Foundation
import Contacts
import ExpoModulesCore

class ContactRepository {
  private let store: CNContactStore
  private var cachedNotesAccess: Bool?

  init(store: CNContactStore) {
    self.store = store
  }

  func delete(id: String) throws {
    let mutableContact = try getMutableById(id: id, keysToFetch: [])
    let saveRequest = CNSaveRequest()
    saveRequest.delete(mutableContact)
    try store.execute(saveRequest)
  }

  func insert(contact: CNMutableContact) throws {
    let saveRequest = CNSaveRequest()
    saveRequest.add(contact, toContainerWithIdentifier: nil)
    try store.execute(saveRequest)
  }

  func update(contact: CNMutableContact) throws {
    let saveRequest = CNSaveRequest()
    saveRequest.update(contact)
    try store.execute(saveRequest)
  }

  func getById(id: String, keysToFetch: [CNKeyDescriptor]) -> CNContact? {
    let safeKeys = getSafeKeys(keysToFetch: keysToFetch)
    return try? store.unifiedContact(withIdentifier: id, keysToFetch: safeKeys)
  }

  func getMutableById(id: String, keysToFetch: [CNKeyDescriptor]) throws -> CNMutableContact {
    let contact = getById(id: id, keysToFetch: getSafeKeys(keysToFetch: keysToFetch))
    guard let mutableContact = contact?.mutableCopy() as? CNMutableContact else {
      throw FailedToGetMutableContact()
    }
    return mutableContact
  }

  func getPaginated(
    keysToFetch: [CNKeyDescriptor],
    predicate: NSPredicate?,
    limit: Int?,
    offset: Int?,
    filter: ((CNContact) -> Bool) = { _ in return true },
    sortOrder: CNContactSortOrder? = CNContactSortOrder.userDefault,
    unifyResults: Bool? = false
  ) throws -> [CNContact] {
    let request = CNContactFetchRequest(keysToFetch: getSafeKeys(keysToFetch: keysToFetch))
    request.unifyResults = unifyResults ?? false
    request.predicate = predicate
    request.sortOrder = sortOrder ?? CNContactSortOrder.userDefault

    var contacts: [CNContact] = []
    var currentIndex = 0
    try store.enumerateContacts(with: request) { contact, stop in
      if !filter(contact) {
        return
      }
      if let offset = offset, currentIndex < offset {
        currentIndex += 1
        return
      }
      contacts.append(contact)
      currentIndex += 1
      if let limit = limit, contacts.count >= limit {
        stop.pointee = true
      }
    }

    return contacts
  }

  func getAll(keysToFetch: [CNKeyDescriptor]) throws -> [CNContact] {
    let request = CNContactFetchRequest(keysToFetch: getSafeKeys(keysToFetch: keysToFetch))
    var contacts: [CNContact] = []

    try store.enumerateContacts(with: request) { contact, _ in
      contacts.append(contact)
    }

    return contacts
  }

  func getCount() throws -> Int {
    let request = CNContactFetchRequest(keysToFetch: [])
    var count = 0
    try store.enumerateContacts(with: request) { _, _ in
      count += 1
    }
    return count
  }

  func hasAny() throws -> Bool {
    let request = CNContactFetchRequest(keysToFetch: [])
    var result = false
    try store.enumerateContacts(with: request) { _, stop in
      result = true
      stop.pointee = true
    }
    return result
  }

  private func getSafeKeys(keysToFetch: [CNKeyDescriptor]) -> [CNKeyDescriptor] {
    return keysToFetch.filter { key in
      if let keyString = key as? String, keyString == CNContactNoteKey {
        return canAccessNotesField()
      }
      return true
    }
  }

  private func canAccessNotesField() -> Bool {
    if let cached = cachedNotesAccess {
      return cached
    }
    let fetchRequest = CNContactFetchRequest(keysToFetch: [CNContactNoteKey as CNKeyDescriptor])
    do {
      try store.enumerateContacts(with: fetchRequest) { (contact, stop) in
        stop.pointee = true
      }
    } catch {
      return false
    }
    return true
  }
}