using System.Security.Claims;
using System.Text.Json;
using Microsoft.AspNetCore.Components.Authorization;
using NexusReader.Application.Abstractions.Services;
using NexusReader.UI.Shared.Constants;

namespace NexusReader.UI.Shared.Services;

public class NexusAuthenticationStateProvider : AuthenticationStateProvider
{
    private readonly INativeStorageService _storageService;
    private const string TokenKey = StorageKeys.AuthToken;

    public NexusAuthenticationStateProvider(INativeStorageService storageService)
    {
        _storageService = storageService;
    }

    public void ClearCache()
    {
        _cachedState = null;
        NotifyAuthenticationStateChanged(GetAuthenticationStateAsync());
    }

    private AuthenticationState? _cachedState;

    public override async Task<AuthenticationState> GetAuthenticationStateAsync()
    {
        try
        {
            if (_cachedState != null) return _cachedState;

            var tokenResult = await _storageService.GetSecureString(TokenKey);
            var token = tokenResult.IsSuccess ? tokenResult.Value : null;

            // 1. Try Token-based auth
            if (!string.IsNullOrWhiteSpace(token))
            {
                var emailResult = await _storageService.GetSecureString(StorageKeys.UserEmail);
                var tenantIdResult = await _storageService.GetSecureString(StorageKeys.UserTenant);

                if (emailResult.IsSuccess && !string.IsNullOrEmpty(emailResult.Value))
                {
                    _cachedState = CreateState(emailResult.Value, tenantIdResult.IsSuccess ? tenantIdResult.Value! : "unknown", "OpaqueBearer");
                    return _cachedState;
                }
            }

            // 2. Try Cookie-based auth indicators
            var storedEmailResult = await _storageService.GetSecureString(StorageKeys.UserEmail);
            if (storedEmailResult.IsSuccess && !string.IsNullOrEmpty(storedEmailResult.Value))
            {
                var tenantIdResult = await _storageService.GetSecureString(StorageKeys.UserTenant);
                _cachedState = CreateState(storedEmailResult.Value, tenantIdResult.IsSuccess ? tenantIdResult.Value! : "unknown", "CookieAuth");
                return _cachedState;
            }

            // 3. Fallback: If we have no local info, we might still have a cookie (e.g. after refresh or Google login).
            // We should return anonymous for now but trigger a background check if we're in WASM.
            // Wait! In WASM, the first GetAuthenticationStateAsync is awaited. 
            // We can do a quick check here if it's the first time.
            return new AuthenticationState(new ClaimsPrincipal(new ClaimsIdentity()));
        }
        catch (Exception)
        {
            return new AuthenticationState(new ClaimsPrincipal(new ClaimsIdentity()));
        }
    }

    private AuthenticationState CreateState(string email, string tenantId, string authType)
    {
        var claims = new List<Claim>
        {
            new Claim(ClaimTypes.Name, email),
            new Claim(ClaimTypes.Email, email),
            new Claim("TenantId", tenantId)
        };
        var identity = new ClaimsIdentity(claims, authType);
        return new AuthenticationState(new ClaimsPrincipal(identity));
    }

    public void NotifyUserAuthentication(string email, string tenantId)
    {
        _cachedState = CreateState(email, tenantId, "OpaqueBearer");
        NotifyAuthenticationStateChanged(Task.FromResult(_cachedState));
    }

    public void NotifyUserLogout()
    {
        _cachedState = null;
        var guest = new ClaimsPrincipal(new ClaimsIdentity());
        NotifyAuthenticationStateChanged(Task.FromResult(new AuthenticationState(guest)));
    }
}