import Foundation

@Observable
@MainActor
final class AccountStore {
    private(set) var accounts: [Account] = []

    private static let storageKey = "qstatus.accounts"

    init() {
        loadAccounts()
    }

    func addAccount(_ account: Account, token: String) throws {
        if accounts.contains(where: {
            $0.serviceType == account.serviceType
                && $0.instanceURL.caseInsensitiveCompare(account.instanceURL) == .orderedSame
                && $0.username.caseInsensitiveCompare(account.username) == .orderedSame
        }) {
            throw PostingError(message: "This account is already added.")
        }

        try KeychainManager.saveToken(token, forAccount: account.keychainKey)
        accounts.append(account)
        saveAccounts()
    }

    func removeAccount(_ account: Account) {
        try? KeychainManager.delete(account: account.keychainKey)
        accounts.removeAll { $0.id == account.id }
        saveAccounts()
    }

    func token(for account: Account) -> String? {
        try? KeychainManager.loadToken(forAccount: account.keychainKey)
    }

    func updateAccount(_ account: Account) {
        if let index = accounts.firstIndex(where: { $0.id == account.id }) {
            accounts[index] = account
            saveAccounts()
        }
    }

    private func saveAccounts() {
        if let data = try? JSONEncoder().encode(accounts) {
            UserDefaults.standard.set(data, forKey: Self.storageKey)
        }
    }

    private func loadAccounts() {
        guard let data = UserDefaults.standard.data(forKey: Self.storageKey),
              let decoded = try? JSONDecoder().decode([Account].self, from: data)
        else { return }
        accounts = decoded
    }
}