//
//  Account.swift
//  meterios
//
//  (c) 2025 Martin "maride" Dessauer
//

import Foundation
import OSLog

enum AccountState: Int {
    case Unknown // No connection attempt has been made yet; basically the startup state
    case Disconnected // Not connected as per user request
    case Failure // Last connection failed
    case Connected // Last connection succeeded
}

/// **Account** resembles an user account in Mete and provides relevant functions to Meterios, like encoding and decoding, the set-up client for this very account and favourites management
@Observable class Account: Identifiable, Codable {
    public let id: UUID = UUID()
    
    private(set) var state: AccountState = .Unknown
    
    private let client: MeteClient
    public let address: String
    public let userID: Int
    
    private(set) var displayName: String?
    private(set) var displayImageURL: URL?
    private(set) var balance: Float?
    
    private var favourites: [Int]
    
    enum CodingKeys: String, CodingKey { case address, userID, favourites }

    init(address: String, userID: Int, favourites: [Int] = []) {
        self.address = address
        self.userID = userID
        self.favourites = favourites
        self.client = MeteClient(address: address, userID: userID)
    }
    
    required convenience init(from decoder : Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        let address = try container.decode(String.self, forKey: .address)
        let userID = try container.decode(Int.self, forKey: .userID)
        let favourites = try container.decode([Int].self, forKey: .favourites)
        self.init(address: address, userID: userID, favourites: favourites)
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(address, forKey: .address)
        try container.encode(userID, forKey: .userID)
        try container.encode(favourites, forKey: .favourites)
    }

    // Ping updates the state of the account by trying to connect to the backend
    func Ping() async {
        do {
            state = try await client.CanConnect() ? .Connected : .Disconnected
        } catch {
            state = .Failure
        }
    }
    
    // Refresh updates the account metadata; failure to do so changes the account state
    func Refresh() async {
        do {
            let user = try await client.GetUser()
            displayName = user.displayName
            displayImageURL = user.displayImageURL
            balance = user.balance
            state = .Connected
        } catch {
            let _ = Logger().error("Unable to refresh user account: \(error)")
            state = .Failure
        }
    }
    
    // GetDrinks returns all drinks for this account and backend
    func GetDrinks() async throws -> Array<MeteClientDrink> {
        return try await client.GetDrinks()
    }
    
    // BookDrink books the specified drink using this account
    func BookDrink(_ drinkID: Int) async throws {
        try await client.BookDrink(drinkID)
        await Refresh()
    }

    // IsFavourite returns true if the given drink ID is a favourite
    func IsFavourite(_ drinkID: Int) -> Bool {
        return favourites.contains(drinkID)
    }

    // AddFavourite adds the given drink ID to the list of favourites
    func AddFavourite(_ drinkID: Int) {
        if !IsFavourite(drinkID) {
            favourites.append(drinkID)
        }
    }

    // RemoveFavourite removes the given drink ID from the favourites list
    func RemoveFavourite(_ drinkID: Int) {
        let index = favourites.firstIndex(where: { $0 == drinkID })
        if index != nil {
            favourites.remove(at: index!)
        }
    }

    // SetFavourite sets if the given drink ID is a favourite
    func SetFavourite(drinkID: Int, shouldBeFavourite: Bool) {
        if IsFavourite(drinkID) && !shouldBeFavourite {
            RemoveFavourite(drinkID)
        } else if !IsFavourite(drinkID) && shouldBeFavourite {
            AddFavourite(drinkID)
        }
    }
}