using System.Text;
using System.Text.Json;
using System.Text.Json.Serialization;
using LittleShop.Enums;

namespace LittleShop.Services;

public class SilverPayService : ISilverPayService
{
    private readonly HttpClient _httpClient;
    private readonly IConfiguration _configuration;
    private readonly ILogger<SilverPayService> _logger;
    private readonly string _baseUrl;
    private readonly string _apiKey;
    private readonly string _webhookSecret;

    public SilverPayService(
        HttpClient httpClient,
        IConfiguration configuration,
        ILogger<SilverPayService> logger)
    {
        _httpClient = httpClient;
        _configuration = configuration;
        _logger = logger;

        _baseUrl = _configuration["SilverPay:BaseUrl"] ?? throw new ArgumentException("SilverPay:BaseUrl not configured");
        _apiKey = _configuration["SilverPay:ApiKey"] ?? "";
        _webhookSecret = _configuration["SilverPay:WebhookSecret"] ?? "";

        // Configure HTTP client
        _httpClient.BaseAddress = new Uri(_baseUrl);
        _httpClient.DefaultRequestHeaders.Add("Accept", "application/json");

        if (!string.IsNullOrEmpty(_apiKey))
        {
            _httpClient.DefaultRequestHeaders.Add("X-API-Key", _apiKey);
        }

        _logger.LogInformation("Initialized SilverPAY connection to {BaseUrl}", _baseUrl);
    }

    public async Task<SilverPayOrderResponse> CreateOrderAsync(
        string externalId,
        decimal amount,
        CryptoCurrency currency,
        string? description = null,
        string? webhookUrl = null)
    {
        try
        {
            var currencyCode = GetSilverPayCurrency(currency);

            // Prepare request body for SilverPAY
            var request = new
            {
                external_id = externalId,
                fiat_amount = amount,  // Amount in GBP
                fiat_currency = "GBP",
                currency = currencyCode,
                webhook_url = webhookUrl ?? _configuration["SilverPay:DefaultWebhookUrl"],
                expires_in_hours = 24
            };

            var json = JsonSerializer.Serialize(request, new JsonSerializerOptions
            {
                PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
                DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
            });

            var content = new StringContent(json, Encoding.UTF8, "application/json");

            _logger.LogDebug("Creating SilverPAY order - External ID: {ExternalId}, Amount: {Amount} GBP, Currency: {Currency}",
                externalId, amount, currencyCode);

            // Add timeout to prevent hanging
            using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
            var response = await _httpClient.PostAsync("/api/v1/orders", content, cts.Token);

            if (!response.IsSuccessStatusCode)
            {
                var errorContent = await response.Content.ReadAsStringAsync();
                _logger.LogError("Failed to create SilverPAY order. Status: {Status}, Error: {Error}",
                    response.StatusCode, errorContent);

                // Check if it's a server error that might warrant fallback
                if ((int)response.StatusCode >= 500)
                {
                    throw new HttpRequestException($"SilverPAY server error: {response.StatusCode}", null, response.StatusCode);
                }

                throw new InvalidOperationException($"Failed to create SilverPAY order: {response.StatusCode}");
            }

            var responseJson = await response.Content.ReadAsStringAsync();
            var orderResponse = JsonSerializer.Deserialize<SilverPayApiResponse>(responseJson, new JsonSerializerOptions
            {
                PropertyNameCaseInsensitive = true,
                PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower
            });

            if (orderResponse == null)
            {
                throw new InvalidOperationException("Invalid response from SilverPAY");
            }

            _logger.LogInformation("✅ Created SilverPAY order {OrderId} for External ID {ExternalId} - Amount: {Amount} GBP, Currency: {Currency}, Address: {Address}",
                orderResponse.Id, externalId, amount, currencyCode, orderResponse.PaymentAddress);

            return MapToOrderResponse(orderResponse);
        }
        catch (HttpRequestException ex)
        {
            _logger.LogError(ex, "Network error creating SilverPAY order");
            throw new InvalidOperationException("Network error contacting SilverPAY", ex);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "❌ Failed to create SilverPAY order - External ID: {ExternalId}, Amount: {Amount} GBP",
                externalId, amount);
            throw;
        }
    }

    public async Task<SilverPayOrderResponse?> GetOrderStatusAsync(string orderId)
    {
        try
        {
            var response = await _httpClient.GetAsync($"/api/v1/orders/{orderId}");

            if (response.StatusCode == System.Net.HttpStatusCode.NotFound)
            {
                return null;
            }

            if (!response.IsSuccessStatusCode)
            {
                _logger.LogWarning("Failed to get SilverPAY order status. Status: {Status}", response.StatusCode);
                return null;
            }

            var json = await response.Content.ReadAsStringAsync();
            var orderResponse = JsonSerializer.Deserialize<SilverPayApiResponse>(json, new JsonSerializerOptions
            {
                PropertyNameCaseInsensitive = true,
                PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower
            });

            return orderResponse != null ? MapToOrderResponse(orderResponse) : null;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error getting SilverPAY order status for {OrderId}", orderId);
            return null;
        }
    }

    public Task<bool> ValidateWebhookAsync(string payload, string signature)
    {
        try
        {
            // SilverPAY webhook validation
            // The exact format depends on SilverPAY's implementation
            // This is a common HMAC-SHA256 validation pattern

            if (string.IsNullOrEmpty(_webhookSecret))
            {
                _logger.LogWarning("Webhook secret not configured, skipping validation");
                return Task.FromResult(true); // Allow in development
            }

            var secretBytes = Encoding.UTF8.GetBytes(_webhookSecret);
            var payloadBytes = Encoding.UTF8.GetBytes(payload);

            using var hmac = new System.Security.Cryptography.HMACSHA256(secretBytes);
            var computedHash = hmac.ComputeHash(payloadBytes);
            var computedHashHex = Convert.ToHexString(computedHash).ToLowerInvariant();

            // SilverPAY might use different signature formats
            // Adjust based on actual implementation
            var expectedHash = signature.Replace("sha256=", "").ToLowerInvariant();

            return Task.FromResult(computedHashHex.Equals(expectedHash, StringComparison.OrdinalIgnoreCase));
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error validating webhook signature");
            return Task.FromResult(false);
        }
    }

    public async Task<decimal?> GetExchangeRateAsync(string cryptoCurrency, string fiatCurrency = "GBP")
    {
        try
        {
            var response = await _httpClient.GetAsync($"/api/v1/exchange-rates?crypto={cryptoCurrency}&fiat={fiatCurrency}");

            if (!response.IsSuccessStatusCode)
            {
                return null;
            }

            var json = await response.Content.ReadAsStringAsync();
            var rateResponse = JsonSerializer.Deserialize<ExchangeRateResponse>(json, new JsonSerializerOptions
            {
                PropertyNameCaseInsensitive = true
            });

            return rateResponse?.Rate;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error getting exchange rate for {Crypto}/{Fiat}", cryptoCurrency, fiatCurrency);
            return null;
        }
    }

    private static string GetSilverPayCurrency(CryptoCurrency currency)
    {
        return currency switch
        {
            CryptoCurrency.BTC => "BTC",
            CryptoCurrency.XMR => "XMR",  // Monero not directly supported, might need mapping
            CryptoCurrency.USDT => "USDT", // Might map to ETH for USDT on Ethereum
            CryptoCurrency.LTC => "LTC",
            CryptoCurrency.ETH => "ETH",
            CryptoCurrency.ZEC => "ZEC",   // Zcash might not be supported
            CryptoCurrency.DASH => "DASH", // Dash might not be supported
            CryptoCurrency.DOGE => "DOGE", // Dogecoin might not be supported
            _ => "BTC"
        };
    }

    private static SilverPayOrderResponse MapToOrderResponse(SilverPayApiResponse apiResponse)
    {
        return new SilverPayOrderResponse
        {
            Id = apiResponse.Id,
            ExternalId = apiResponse.ExternalId,
            Amount = apiResponse.Amount,
            Currency = apiResponse.Currency,
            PaymentAddress = apiResponse.PaymentAddress,
            Status = apiResponse.Status,
            CreatedAt = apiResponse.CreatedAt,
            ExpiresAt = apiResponse.ExpiresAt,
            PaidAt = apiResponse.PaidAt,
            PaymentDetails = apiResponse.PaymentDetails,
            CryptoAmount = apiResponse.CryptoAmount,
            TransactionHash = apiResponse.TransactionHash,
            Confirmations = apiResponse.Confirmations
        };
    }

    // Internal classes for JSON deserialization
    private class SilverPayApiResponse
    {
        [JsonPropertyName("id")]
        public string Id { get; set; } = string.Empty;

        [JsonPropertyName("external_id")]
        public string ExternalId { get; set; } = string.Empty;

        [JsonPropertyName("amount")]
        public decimal Amount { get; set; }

        [JsonPropertyName("currency")]
        public string Currency { get; set; } = string.Empty;

        [JsonPropertyName("payment_address")]
        public string PaymentAddress { get; set; } = string.Empty;

        [JsonPropertyName("status")]
        public string Status { get; set; } = string.Empty;

        [JsonPropertyName("created_at")]
        public DateTime CreatedAt { get; set; }

        [JsonPropertyName("expires_at")]
        public DateTime ExpiresAt { get; set; }

        [JsonPropertyName("paid_at")]
        public DateTime? PaidAt { get; set; }

        [JsonPropertyName("payment_details")]
        public Dictionary<string, object>? PaymentDetails { get; set; }

        [JsonPropertyName("crypto_amount")]
        public decimal? CryptoAmount { get; set; }

        [JsonPropertyName("tx_hash")]
        public string? TransactionHash { get; set; }

        [JsonPropertyName("confirmations")]
        public int? Confirmations { get; set; }
    }

    private class ExchangeRateResponse
    {
        [JsonPropertyName("crypto")]
        public string Crypto { get; set; } = string.Empty;

        [JsonPropertyName("fiat")]
        public string Fiat { get; set; } = string.Empty;

        [JsonPropertyName("rate")]
        public decimal Rate { get; set; }

        [JsonPropertyName("timestamp")]
        public DateTime Timestamp { get; set; }
    }
}