using System;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Authorization;
using System.Net.Http;
using System.Security.Cryptography;
using Bit.Core.Services;
using Bit.Core;
using System.Net;
using Bit.Core.Exceptions;
using System.Linq;
using Bit.Core.Utilities;

namespace Bit.Api.Controllers
{
    [Route("hibp")]
    [Authorize("Application")]
    public class HibpController : Controller
    {
        private const string HibpBreachApi = "https://haveibeenpwned.com/api/v3/breachedaccount/{0}" +
            "?truncateResponse=false&includeUnverified=false";
        private static HttpClient _httpClient;

        private readonly IUserService _userService;
        private readonly CurrentContext _currentContext;
        private readonly GlobalSettings _globalSettings;
        private readonly string _userAgent;

        static HibpController()
        {
            _httpClient = new HttpClient();
        }

        public HibpController(
            IUserService userService,
            CurrentContext currentContext,
            GlobalSettings globalSettings)
        {
            _userService = userService;
            _currentContext = currentContext;
            _globalSettings = globalSettings;
            _userAgent = _globalSettings.SelfHosted ? "Bitwarden Self-Hosted" : "Bitwarden";
        }

        [HttpGet("breach")]
        public async Task<IActionResult> Get(string username)
        {
            return await SendAsync(WebUtility.UrlEncode(username), true);
        }

        private async Task<IActionResult> SendAsync(string username, bool retry)
        {
            if (!CoreHelpers.SettingHasValue(_globalSettings.HibpApiKey))
            {
                throw new BadRequestException("HaveIBeenPwned API key not set.");
            }
            var request = new HttpRequestMessage(HttpMethod.Get, string.Format(HibpBreachApi, username));
            request.Headers.Add("hibp-api-key", _globalSettings.HibpApiKey);
            request.Headers.Add("hibp-client-id", GetClientId());
            request.Headers.Add("User-Agent", _userAgent);
            var response = await _httpClient.SendAsync(request);
            if (response.IsSuccessStatusCode)
            {
                var data = await response.Content.ReadAsStringAsync();
                return Content(data, "application/json");
            }
            else if (response.StatusCode == HttpStatusCode.NotFound)
            {
                return new NotFoundResult();
            }
            else if (response.StatusCode == HttpStatusCode.TooManyRequests && retry)
            {
                var delay = 2000;
                if (response.Headers.Contains("retry-after"))
                {
                    var vals = response.Headers.GetValues("retry-after");
                    if (vals.Any() && int.TryParse(vals.FirstOrDefault(), out var secDelay))
                    {
                        delay = (secDelay * 1000) + 200;
                    }
                }
                await Task.Delay(delay);
                return await SendAsync(username, false);
            }
            else
            {
                throw new BadRequestException("Request failed. Status code: " + response.StatusCode);
            }
        }

        private string GetClientId()
        {
            var userId = _userService.GetProperUserId(User).Value;
            using (var sha256 = SHA256.Create())
            {
                var hash = sha256.ComputeHash(userId.ToByteArray());
                return Convert.ToBase64String(hash);
            }
        }
    }
}
