using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;
using Fitness_core_BE.DTOs.PaymentGateways;
using Fitness_core_BE.Exceptions;
using Fitness_core_BE.Interfaces.Services;

namespace Fitness_core_BE.Services
{
    public class PaymentServiceClient : IPaymentServiceClient
    {
        private readonly HttpClient _httpClient;
        private readonly string _baseUrl;
        private readonly string _internalKey;
        private static readonly JsonSerializerOptions JsonOptions = new() { PropertyNameCaseInsensitive = true };

        public PaymentServiceClient(IHttpClientFactory httpClientFactory, IConfiguration configuration)
        {
            _httpClient = httpClientFactory.CreateClient();
            _baseUrl = (configuration["PaymentService:BaseUrl"] ?? "http://127.0.0.1:5120").TrimEnd('/');
            _internalKey = configuration["PaymentService:InternalApiKey"] ?? string.Empty;
        }

        public async Task<List<GatewayDefinitionDto>> ListGatewaysAsync(CancellationToken cancellationToken = default)
        {
            var response = await SendAsync(HttpMethod.Get, "/api/v1/gateways", null, cancellationToken);
            var body = await response.Content.ReadAsStringAsync(cancellationToken);
            return JsonSerializer.Deserialize<List<GatewayDefinitionDto>>(body, JsonOptions) ?? new List<GatewayDefinitionDto>();
        }

        public async Task<GatewayDefinitionDto> UpsertGatewayAsync(UpsertGatewayDefinitionRequest request, CancellationToken cancellationToken = default)
        {
            var response = await SendAsync(HttpMethod.Post, "/api/v1/gateways", request, cancellationToken);
            var body = await response.Content.ReadAsStringAsync(cancellationToken);
            return JsonSerializer.Deserialize<GatewayDefinitionDto>(body, JsonOptions)
                ?? throw new ServiceUnavailableException("Payment-Service returned an empty gateway response.");
        }

        public async Task<GatewayDefinitionDto> SetGatewayEnabledAsync(Guid id, bool isEnabled, CancellationToken cancellationToken = default)
        {
            var response = await SendAsync(HttpMethod.Put, $"/api/v1/gateways/{id}/enabled", new { isEnabled }, cancellationToken);
            var body = await response.Content.ReadAsStringAsync(cancellationToken);
            return JsonSerializer.Deserialize<GatewayDefinitionDto>(body, JsonOptions)
                ?? throw new ServiceUnavailableException("Payment-Service returned an empty gateway response.");
        }

        public async Task UpsertPlatformCredentialAsync(UpsertPlatformGatewayCredentialRequest request, CancellationToken cancellationToken = default)
        {
            await SendAsync(
                HttpMethod.Put,
                $"/api/v1/gateways/platforms/{request.PlatformId}/credentials/{request.GatewayName}",
                new { credentialsJson = request.CredentialsJson },
                cancellationToken);
        }

        public async Task<(Guid PlatformId, string ApiKey, string HmacSecret)> ProvisionPlatformAsync(
            Guid clientId, string displayName, CancellationToken cancellationToken = default)
        {
            var response = await SendAsync(
                HttpMethod.Post,
                "/api/v1/platforms",
                new { externalClientId = clientId, displayName },
                cancellationToken);

            var body = await response.Content.ReadAsStringAsync(cancellationToken);
            using var doc = JsonDocument.Parse(body);
            var platformId = doc.RootElement.GetProperty("platformId").GetGuid();
            var apiKey = doc.RootElement.GetProperty("apiKey").GetString() ?? string.Empty;
            var hmacSecret = doc.RootElement.GetProperty("hmacSecret").GetString() ?? string.Empty;

            return (platformId, apiKey, hmacSecret);
        }

        private async Task<HttpResponseMessage> SendAsync(HttpMethod method, string path, object? body, CancellationToken cancellationToken)
        {
            using var request = new HttpRequestMessage(method, $"{_baseUrl}{path}");
            request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            request.Headers.Add("X-Internal-Key", _internalKey);

            if (body is not null)
            {
                request.Content = new StringContent(JsonSerializer.Serialize(body), Encoding.UTF8, "application/json");
            }

            HttpResponseMessage response;
            try
            {
                response = await _httpClient.SendAsync(request, cancellationToken);
            }
            catch (HttpRequestException ex)
            {
                throw new ServiceUnavailableException("Could not reach Payment-Service.", ex);
            }

            if (!response.IsSuccessStatusCode)
            {
                var errorBody = await response.Content.ReadAsStringAsync(cancellationToken);
                throw new ServiceUnavailableException($"Payment-Service call failed ({(int)response.StatusCode}): {errorBody}");
            }

            return response;
        }
    }
}