using System;
using System.Threading.Tasks;
using UnityEngine;

public sealed class BriskPlayerPrefsTokenStore : IBriskTokenStore
{
    private const string KeyPrefix = "BriskSdk.Session.";

    public Task SaveAsync(BriskStoredSession session)
    {
        if (session == null)
        {
            ClearStoredKeys();
            return Task.CompletedTask;
        }

        SetString("access_token", session.AccessToken);
        SetString("expires_at", session.ExpiresAt.HasValue ? session.ExpiresAt.Value.ToUnixTimeSeconds().ToString() : null);
        SetString("player_id", session.PlayerId);
        SetString("project_account_id", session.ProjectAccountId);
        SetString("login_provider", session.LoginProvider);
        SetString("login_user_id", session.LoginUserId);
        PlayerPrefs.Save();
        return Task.CompletedTask;
    }

    public Task<BriskStoredSession> LoadAsync()
    {
        var accessToken = GetString("access_token");
        if (string.IsNullOrWhiteSpace(accessToken))
        {
            return Task.FromResult<BriskStoredSession>(null);
        }

        DateTimeOffset? expiresAt = null;
        var expiresAtText = GetString("expires_at");
        if (long.TryParse(expiresAtText, out var unixSeconds))
        {
            expiresAt = DateTimeOffset.FromUnixTimeSeconds(unixSeconds);
        }

        var session = new BriskStoredSession
        {
            AccessToken = accessToken,
            ExpiresAt = expiresAt,
            PlayerId = GetString("player_id"),
            ProjectAccountId = GetString("project_account_id"),
            LoginProvider = GetString("login_provider"),
            LoginUserId = GetString("login_user_id")
        };
        return Task.FromResult(session);
    }

    public Task ClearAsync()
    {
        ClearStoredKeys();
        PlayerPrefs.Save();
        return Task.CompletedTask;
    }

    private static void ClearStoredKeys()
    {
        PlayerPrefs.DeleteKey(KeyPrefix + "access_token");
        PlayerPrefs.DeleteKey(KeyPrefix + "expires_at");
        PlayerPrefs.DeleteKey(KeyPrefix + "player_id");
        PlayerPrefs.DeleteKey(KeyPrefix + "project_account_id");
        PlayerPrefs.DeleteKey(KeyPrefix + "login_provider");
        PlayerPrefs.DeleteKey(KeyPrefix + "login_user_id");
    }

    private static string GetString(string name)
    {
        var key = KeyPrefix + name;
        return PlayerPrefs.HasKey(key) ? PlayerPrefs.GetString(key) : null;
    }

    private static void SetString(string name, string value)
    {
        var key = KeyPrefix + name;
        if (string.IsNullOrEmpty(value))
        {
            PlayerPrefs.DeleteKey(key);
            return;
        }

        PlayerPrefs.SetString(key, value);
    }
}