using SharpChat.Config;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

namespace SharpChat.Misuzu {
    public class MisuzuClient {
        private const string DEFAULT_BASE_URL = "https://flashii.net/_sockchat";
        private const string DEFAULT_SECRET_KEY = "woomy";

        private const string BUMP_ONLINE_URL = "{0}/bump";
        private const string AUTH_VERIFY_URL = "{0}/verify";

        private const string BANS_CHECK_URL = "{0}/bans/check?u={1}&a={2}&x={3}&n={4}";
        private const string BANS_CREATE_URL = "{0}/bans/create";
        private const string BANS_REVOKE_URL = "{0}/bans/revoke?t={1}&s={2}&x={3}";
        private const string BANS_LIST_URL = "{0}/bans/list?x={1}";

        private const string VERIFY_SIG = "verify#{0}#{1}#{2}";
        private const string BANS_CHECK_SIG = "check#{0}#{1}#{2}#{3}";
        private const string BANS_REVOKE_SIG = "revoke#{0}#{1}#{2}";
        private const string BANS_CREATE_SIG = "create#{0}#{1}#{2}#{3}#{4}#{5}#{6}#{7}";
        private const string BANS_LIST_SIG = "list#{0}";

        private readonly HttpClient HttpClient;

        private CachedValue<string> BaseURL { get; }
        private CachedValue<string> SecretKey { get; }

        public MisuzuClient(HttpClient httpClient, IConfig config) {
            if(config == null)
                throw new ArgumentNullException(nameof(config));
            HttpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));

            BaseURL = config.ReadCached("url", DEFAULT_BASE_URL);
            SecretKey = config.ReadCached("secret", DEFAULT_SECRET_KEY);
        }

        public string CreateStringSignature(string str) {
            return CreateBufferSignature(Encoding.UTF8.GetBytes(str));
        }

        public string CreateBufferSignature(byte[] bytes) {
            using HMACSHA256 algo = new(Encoding.UTF8.GetBytes(SecretKey.Value ?? string.Empty));
            return string.Concat(algo.ComputeHash(bytes).Select(c => c.ToString("x2")));
        }

        public async Task<MisuzuAuthInfo?> AuthVerifyAsync(string method, string token, string ipAddr) {
            method ??= string.Empty;
            token ??= string.Empty;
            ipAddr ??= string.Empty;

            string sig = string.Format(VERIFY_SIG, method, token, ipAddr);

            HttpRequestMessage req = new(HttpMethod.Post, string.Format(AUTH_VERIFY_URL, BaseURL)) {
                Content = new FormUrlEncodedContent(new Dictionary<string, string> {
                    { "method", method },
                    { "token", token },
                    { "ipaddr", ipAddr },
                }),
                Headers = {
                    { "X-SharpChat-Signature", CreateStringSignature(sig) },
                },
            };

            using HttpResponseMessage res = await HttpClient.SendAsync(req);

            return JsonSerializer.Deserialize<MisuzuAuthInfo>(
                await res.Content.ReadAsByteArrayAsync()
            );
        }

        public async Task BumpUsersOnlineAsync(IEnumerable<(string userId, string ipAddr)> list) {
            if(list == null)
                throw new ArgumentNullException(nameof(list));
            if(!list.Any())
                return;

            string now = DateTimeOffset.UtcNow.ToUnixTimeSeconds().ToString();
            StringBuilder sb = new();
            sb.AppendFormat("bump#{0}", now);

            Dictionary<string, string> formData = new() {
                { "t", now }
            };

            foreach(var (userId, ipAddr) in list) {
                sb.AppendFormat("#{0}:{1}", userId, ipAddr);
                formData.Add(string.Format("u[{0}]", userId), ipAddr);
            }

            HttpRequestMessage req = new(HttpMethod.Post, string.Format(BUMP_ONLINE_URL, BaseURL)) {
                Headers = {
                    { "X-SharpChat-Signature", CreateStringSignature(sb.ToString()) }
                },
                Content = new FormUrlEncodedContent(formData),
            };

            using HttpResponseMessage res = await HttpClient.SendAsync(req);

            try {
                res.EnsureSuccessStatusCode();
            } catch(HttpRequestException) {
                Logger.Debug(await res.Content.ReadAsStringAsync());
#if DEBUG
                throw;
#endif
            }
        }

        public async Task<MisuzuBanInfo?> CheckBanAsync(
            string? userId = null,
            string? ipAddr = null,
            bool userIdIsName = false
        ) {
            userId ??= string.Empty;
            ipAddr ??= string.Empty;

            string userIdIsNameStr = userIdIsName ? "1" : "0";
            string now = DateTimeOffset.Now.ToUnixTimeSeconds().ToString();
            string url = string.Format(BANS_CHECK_URL, BaseURL, Uri.EscapeDataString(userId), Uri.EscapeDataString(ipAddr), Uri.EscapeDataString(now), Uri.EscapeDataString(userIdIsNameStr));
            string sig = string.Format(BANS_CHECK_SIG, now, userId, ipAddr, userIdIsNameStr);

            HttpRequestMessage req = new(HttpMethod.Get, url) {
                Headers = {
                    { "X-SharpChat-Signature", CreateStringSignature(sig) },
                },
            };

            using HttpResponseMessage res = await HttpClient.SendAsync(req);

            return JsonSerializer.Deserialize<MisuzuBanInfo>(
                await res.Content.ReadAsByteArrayAsync()
            );
        }

        public async Task<MisuzuBanInfo[]?> GetBanListAsync() {
            string now = DateTimeOffset.Now.ToUnixTimeSeconds().ToString();
            string url = string.Format(BANS_LIST_URL, BaseURL, Uri.EscapeDataString(now));
            string sig = string.Format(BANS_LIST_SIG, now);

            HttpRequestMessage req = new(HttpMethod.Get, url) {
                Headers = {
                    { "X-SharpChat-Signature", CreateStringSignature(sig) },
                },
            };

            using HttpResponseMessage res = await HttpClient.SendAsync(req);

            return JsonSerializer.Deserialize<MisuzuBanInfo[]>(
                await res.Content.ReadAsByteArrayAsync()
            );
        }

        public enum BanRevokeKind {
            UserId,
            RemoteAddress,
        }

        public async Task<bool> RevokeBanAsync(MisuzuBanInfo banInfo, BanRevokeKind kind) {
            if(banInfo == null)
                throw new ArgumentNullException(nameof(banInfo));

            string type = kind switch {
                BanRevokeKind.UserId => "user",
                BanRevokeKind.RemoteAddress => "addr",
                _ => throw new ArgumentException("Invalid kind specified.", nameof(kind)),
            };

            string target = kind switch {
                BanRevokeKind.UserId => banInfo?.UserId ?? string.Empty,
                BanRevokeKind.RemoteAddress => banInfo?.RemoteAddress ?? string.Empty,
                _ => string.Empty,
            };

            string now = DateTimeOffset.Now.ToUnixTimeSeconds().ToString();
            string url = string.Format(BANS_REVOKE_URL, BaseURL, Uri.EscapeDataString(type), Uri.EscapeDataString(target), Uri.EscapeDataString(now));
            string sig = string.Format(BANS_REVOKE_SIG, now, type, target);

            HttpRequestMessage req = new(HttpMethod.Delete, url) {
                Headers = {
                    { "X-SharpChat-Signature", CreateStringSignature(sig) },
                },
            };

            using HttpResponseMessage res = await HttpClient.SendAsync(req);

            if(res.StatusCode == HttpStatusCode.NotFound)
                return false;

            res.EnsureSuccessStatusCode();

            return res.StatusCode == HttpStatusCode.NoContent;
        }

        public async Task CreateBanAsync(
            string targetId,
            string targetAddr,
            string modId,
            string modAddr,
            TimeSpan duration,
            string reason
        ) {
            if(string.IsNullOrWhiteSpace(targetAddr))
                throw new ArgumentNullException(nameof(targetAddr));
            if(string.IsNullOrWhiteSpace(modAddr))
                throw new ArgumentNullException(nameof(modAddr));
            if(duration <= TimeSpan.Zero)
                return;

            modId ??= string.Empty;
            targetId ??= string.Empty;
            reason ??= string.Empty;

            string isPerma = duration == TimeSpan.MaxValue ? "1" : "0";
            string durationStr = duration == TimeSpan.MaxValue ? "-1" : duration.TotalSeconds.ToString();

            string now = DateTimeOffset.Now.ToUnixTimeSeconds().ToString();
            string sig = string.Format(
                BANS_CREATE_SIG,
                now, targetId, targetAddr,
                modId, modAddr,
                durationStr, isPerma, reason
            );

            HttpRequestMessage req = new(HttpMethod.Post, string.Format(BANS_CREATE_URL, BaseURL)) {
                Headers = {
                    { "X-SharpChat-Signature", CreateStringSignature(sig) },
                },
                Content = new FormUrlEncodedContent(new Dictionary<string, string> {
                    { "t", now },
                    { "ui", targetId },
                    { "ua", targetAddr },
                    { "mi", modId },
                    { "ma", modAddr },
                    { "d", durationStr },
                    { "p", isPerma },
                    { "r", reason },
                }),
            };

            using HttpResponseMessage res = await HttpClient.SendAsync(req);

            res.EnsureSuccessStatusCode();
        }
    }
}