using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;
using Socialize.Api.Infrastructure.Emailer.Configuration;
using Socialize.Api.Infrastructure.Emailer.Contracts;
using Microsoft.Extensions.Options;

namespace Socialize.Api.Infrastructure.Emailer.Services;

public class ResendEmailSender : IEmailSender
{
    private static readonly Uri EndpointUri = new("https://api.resend.com/emails");
    private readonly HttpClient _httpClient;
    private readonly EmailerOptions _options;

    public ResendEmailSender(
        IHttpClientFactory httpClientFactory,
        IOptions<EmailerOptions> options)
    {
        _httpClient = httpClientFactory.CreateClient();
        _options = options.Value;

        string apiKey = NormalizeApiKey(_options.ApiKey);
        string fromEmail = _options.FromEmail?.Trim() ?? string.Empty;

        if (string.IsNullOrWhiteSpace(apiKey))
        {
            throw new InvalidOperationException("Emailer:ApiKey is required when using Resend email delivery.");
        }

        if (string.IsNullOrWhiteSpace(fromEmail))
        {
            throw new InvalidOperationException("Emailer:FromEmail is required when using Resend email delivery.");
        }

        _options.ApiKey = apiKey;
        _options.FromEmail = fromEmail;

        _httpClient.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("Bearer", apiKey);

        _httpClient.DefaultRequestHeaders.Accept.Add(
            new MediaTypeWithQualityHeaderValue("application/json"));
    }

    public async Task SendEmailAsync(string toEmail, string subject, string htmlMessage)
    {
        var payload = new { from = _options.FromEmail, to = toEmail, subject, html = htmlMessage };

        string json = JsonSerializer.Serialize(payload);
        StringContent content = new(json, Encoding.UTF8, "application/json");

        HttpResponseMessage response = await _httpClient.PostAsync(EndpointUri, content);

        if (!response.IsSuccessStatusCode)
        {
            string body = await response.Content.ReadAsStringAsync();
            throw new InvalidOperationException(
                $"Resend email failed: {response.StatusCode} - {body}");
        }
    }

    private static string NormalizeApiKey(string? apiKey)
    {
        string normalized = apiKey?.Trim().Trim('"', '\'') ?? string.Empty;
        const string bearerPrefix = "Bearer ";
        if (normalized.StartsWith(bearerPrefix, StringComparison.OrdinalIgnoreCase))
        {
            normalized = normalized[bearerPrefix.Length..].Trim();
        }

        return normalized;
    }
}