using System;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Hosting;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using SteamAuth;
using SteamKit2;
using SteamKit2.Authentication;

var builder = WebApplication.CreateBuilder(args);

// ── 限制每个主机的最大并发连接数，防止连接耗尽 ──
System.Net.ServicePointManager.DefaultConnectionLimit = 200;

var app = builder.Build();

// ── 全局异常处理：防止未捕获的异常导致进程崩溃 ──
app.UseExceptionHandler(errorApp =>
{
    errorApp.Run(async context =>
    {
        context.Response.StatusCode = 500;
        context.Response.ContentType = "application/json; charset=utf-8";
        var errorId = Guid.NewGuid().ToString("N")[..8];
        Console.Error.WriteLine($"[UNHANDLED] error_id={errorId} path={context.Request.Path}");
        await context.Response.WriteAsync($"{{\"error\":\"Internal server error\",\"error_id\":\"{errorId}\"}}");
    });
});

// ── 请求超时中间件：防止慢请求永久占用线程 ──
app.Use(async (context, next) =>
{
    using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(60));
    try
    {
        await next.Invoke();
    }
    catch (OperationCanceledException)
    {
        context.Response.StatusCode = 504;
        context.Response.ContentType = "application/json";
        await context.Response.WriteAsync("{\"error\":\"Request timeout\"}");
    }
});

app.MapPost("/login", async (HttpContext http) =>
{
    var req = await GetRequestBodyAsync(http);
    if (req == null)
    {
        http.Response.StatusCode = 400;
        await http.Response.WriteAsync("invalid request");
        return;
    }

    if (!File.Exists(req.MaFilePath))
    {
        http.Response.StatusCode = 400;
        await http.Response.WriteAsync("maFile not found");
        return;
    }

    SteamGuardAccount? account;
    try
    {
        var contents = await File.ReadAllTextAsync(req.MaFilePath);
        account = JsonConvert.DeserializeObject<SteamGuardAccount>(contents);
    }
    catch (Exception ex)
    {
        http.Response.StatusCode = 500;
        await http.Response.WriteAsync("failed to read maFile: " + ex.Message);
        return;
    }

    try
    {
        // Start SteamClient and authenticate using the maFile-provided SteamGuardAccount
        SteamClient steamClient = CreateSteamClient(req.ProxyUrl, app.Logger, "login");
        steamClient.Connect();

        var timeoutMs = 15000;
        var waited = 0;
        while (!steamClient.IsConnected && waited < timeoutMs)
        {
            await Task.Delay(200);
            waited += 200;
        }
        if (!steamClient.IsConnected)
        {
            http.Response.StatusCode = 500;
            await http.Response.WriteAsync("failed to connect to steam network");
            return;
        }

        CredentialsAuthSession authSession = await steamClient.Authentication.BeginAuthSessionViaCredentialsAsync(new AuthSessionDetails
        {
            Username = req.Username,
            Password = req.Password,
            IsPersistentSession = false,
            // PlatformType and ClientOSType are optional; omit to avoid enum symbol differences across SteamKit2 versions.
            Authenticator = new FileAuthenticator(account),
        });

        var pollResponse = await authSession.PollingWaitForResultAsync();

        var sessionData = new SessionData()
        {
            SteamID = authSession.SteamID.ConvertToUInt64(),
            AccessToken = pollResponse.AccessToken,
            RefreshToken = pollResponse.RefreshToken,
        };

        // Serialize cookies
        var uri = new Uri("https://steamcommunity.com");
        var cookies = sessionData.GetCookies().GetCookies(uri).Cast<Cookie>().Select(c => new
        {
            name = c.Name,
            value = c.Value,
            domain = c.Domain,
            path = c.Path,
            expires = c.Expires == DateTime.MinValue ? null : (DateTime?)c.Expires
        }).ToArray();

        var resp = new
        {
            session = new
            {
                steamId = sessionData.SteamID,
                accessToken = sessionData.AccessToken,
                refreshToken = sessionData.RefreshToken,
                sessionId = sessionData.SessionID
            },
            cookies = cookies
        };

        http.Response.ContentType = "application/json";
        await http.Response.WriteAsync(JsonConvert.SerializeObject(resp, Formatting.Indented));
        return;
    }
    catch (Exception ex)
    {
        http.Response.StatusCode = 500;
        await http.Response.WriteAsync("login failed: " + ex.Message);
        return;
    }
});

app.MapPost("/wallet-balance", async (HttpContext http) =>
{
    var req = await GetWalletBalanceRequestBodyAsync(http);
    if (req == null || string.IsNullOrWhiteSpace(req.SteamLoginSecure))
    {
        http.Response.StatusCode = 400;
        await http.Response.WriteAsync("invalid request");
        return;
    }

    try
    {
        var handler = CreateHttpClientHandler(req.ProxyUrl, app.Logger, "wallet-balance");
        using var client = new HttpClient(handler, disposeHandler: true)
        {
            Timeout = TimeSpan.FromSeconds(20)
        };

        var request = new HttpRequestMessage(HttpMethod.Get, "https://store.steampowered.com/api/getfundwalletinfo/?cc=us&l=english");
        request.Headers.Add("Cookie", $"steamLoginSecure={req.SteamLoginSecure}");
        var response = await client.SendAsync(request);
        var body = await response.Content.ReadAsStringAsync();

        if (!response.IsSuccessStatusCode)
        {
            http.Response.StatusCode = 500;
            await http.Response.WriteAsync($"wallet request failed: {(int)response.StatusCode}");
            return;
        }

        var json = JsonConvert.DeserializeObject<JObject>(body);
        if (json == null || json["success"]?.Value<int>() != 1 || json["user_wallet"] is not JObject wallet)
        {
            http.Response.StatusCode = 500;
            await http.Response.WriteAsync("wallet response invalid");
            return;
        }

        var resp = new
        {
            amount = wallet["amount"]?.Value<string>() ?? "0",
            currency = wallet["currency"]?.Value<string>() ?? "USD"
        };

        http.Response.ContentType = "application/json";
        await http.Response.WriteAsync(JsonConvert.SerializeObject(resp));
    }
    catch (Exception ex)
    {
        http.Response.StatusCode = 500;
        await http.Response.WriteAsync("wallet query failed: " + ex.Message);
    }
});

app.MapPost("/trade-confirmations/list", async (HttpContext http) =>
{
    var req = await GetTradeConfirmationsListRequestBodyAsync(http);
    if (req == null || string.IsNullOrWhiteSpace(req.MaFilePath) || req.Session == null)
    {
        http.Response.StatusCode = 400;
        await http.Response.WriteAsync("invalid request");
        return;
    }

    if (!File.Exists(req.MaFilePath))
    {
        http.Response.StatusCode = 400;
        await http.Response.WriteAsync("maFile not found");
        return;
    }

    try
    {
        var (proxyUrl, source) = ResolveProxyUrl(req.ProxyUrl);
        app.Logger.LogInformation(
            "[{Endpoint}] Proxy resolved. source={Source}, value={Proxy}",
            "trade-confirmations/list",
            source,
            MaskProxyUrlForLog(proxyUrl)
        );
        app.Logger.LogInformation(
            "[{Endpoint}] Calling Steam confirmation list. mode={Mode}, proxy={Proxy}",
            "trade-confirmations/list",
            string.IsNullOrWhiteSpace(proxyUrl) ? "direct" : "proxy",
            MaskProxyUrlForLog(proxyUrl)
        );

        var account = await BuildAccountWithSessionAsync(req.MaFilePath, req.Session);
        if (account == null)
        {
            http.Response.StatusCode = 500;
            await http.Response.WriteAsync("failed to build steam account session");
            return;
        }

        if (account.Session.IsRefreshTokenExpired())
        {
            http.Response.StatusCode = 401;
            await http.Response.WriteAsync("session refresh token expired");
            return;
        }

        var accessTokenRefreshed = false;
        if (account.Session.IsAccessTokenExpired())
        {
            await account.Session.RefreshAccessToken();
            accessTokenRefreshed = true;
        }

        var confirmations = await account.FetchConfirmationsAsync(proxyUrl);
        var resp = new
        {
            session = new
            {
                steamId = account.Session.SteamID,
                accessToken = account.Session.AccessToken,
                refreshToken = account.Session.RefreshToken,
                sessionId = account.Session.SessionID,
                accessTokenRefreshed
            },
            confirmations = confirmations.Select(c => new
            {
                id = c.ID,
                key = c.Key,
                creatorId = c.Creator,
                type = c.ConfType.ToString(),
                headline = c.Headline,
                summary = c.Summary,
                accept = c.Accept,
                cancel = c.Cancel,
                icon = c.Icon
            }).ToArray()
        };

        http.Response.ContentType = "application/json";
        await http.Response.WriteAsync(JsonConvert.SerializeObject(resp));
    }
    catch (Exception ex)
    {
        http.Response.StatusCode = 500;
        await http.Response.WriteAsync("fetch confirmations failed: " + ex.Message);
    }
});

app.MapPost("/trade-confirmations/operate", async (HttpContext http) =>
{
    var req = await GetTradeConfirmationOperateRequestBodyAsync(http);
    if (req == null
        || string.IsNullOrWhiteSpace(req.MaFilePath)
        || req.Session == null
        || req.ConfirmationId == 0
        || string.IsNullOrWhiteSpace(req.Operation))
    {
        http.Response.StatusCode = 400;
        await http.Response.WriteAsync("invalid request");
        return;
    }

    if (!File.Exists(req.MaFilePath))
    {
        http.Response.StatusCode = 400;
        await http.Response.WriteAsync("maFile not found");
        return;
    }

    var op = req.Operation.Trim().ToLowerInvariant();
    if (op != "accept" && op != "cancel")
    {
        http.Response.StatusCode = 400;
        await http.Response.WriteAsync("invalid operation, expected accept or cancel");
        return;
    }

    try
    {
        var (proxyUrl, source) = ResolveProxyUrl(req.ProxyUrl);
        app.Logger.LogInformation(
            "[{Endpoint}] Proxy resolved. source={Source}, value={Proxy}",
            "trade-confirmations/operate",
            source,
            MaskProxyUrlForLog(proxyUrl)
        );
        app.Logger.LogInformation(
            "[{Endpoint}] Calling Steam confirmation operation. op={Op}, mode={Mode}, proxy={Proxy}",
            "trade-confirmations/operate",
            op,
            string.IsNullOrWhiteSpace(proxyUrl) ? "direct" : "proxy",
            MaskProxyUrlForLog(proxyUrl)
        );

        var account = await BuildAccountWithSessionAsync(req.MaFilePath, req.Session);
        if (account == null)
        {
            http.Response.StatusCode = 500;
            await http.Response.WriteAsync("failed to build steam account session");
            return;
        }

        if (account.Session.IsRefreshTokenExpired())
        {
            http.Response.StatusCode = 401;
            await http.Response.WriteAsync("session refresh token expired");
            return;
        }

        var accessTokenRefreshed = false;
        if (account.Session.IsAccessTokenExpired())
        {
            await account.Session.RefreshAccessToken();
            accessTokenRefreshed = true;
        }

        ulong confirmationKey = req.ConfirmationKey ?? 0;
        ulong effectiveConfirmationId = req.ConfirmationId;
        var keyResolvedFromList = false;
        var idResolvedFromList = false;
        var matchedBy = "request";
        if (confirmationKey == 0)
        {
            var confirmations = await account.FetchConfirmationsAsync(proxyUrl);
            var matched = confirmations.FirstOrDefault(c => c.ID == req.ConfirmationId);
            if (matched != null)
            {
                matchedBy = "id";
            }
            else
            {
                // buylisting 返回的 confirmation_id 在部分场景为 creator_id，
                // 这里回退按 creator_id 匹配，便于调用方仅传一个确认订单号即可完成确认。
                matched = confirmations.FirstOrDefault(c => c.Creator == req.ConfirmationId);
                if (matched != null)
                {
                    matchedBy = "creator_id";
                }
            }
            if (matched == null || matched.Key == 0)
            {
                http.Response.StatusCode = 404;
                await http.Response.WriteAsync("confirmation not found or key unavailable");
                return;
            }

            effectiveConfirmationId = matched.ID;
            confirmationKey = matched.Key;
            keyResolvedFromList = true;
            idResolvedFromList = true;
        }

        var confirmation = new Confirmation
        {
            ID = effectiveConfirmationId,
            Key = confirmationKey
        };

        var success = op == "accept"
            ? await account.AcceptConfirmation(confirmation, proxyUrl)
            : await account.DenyConfirmation(confirmation, proxyUrl);

        var resp = new
        {
            success,
            operation = op,
            requestedConfirmationId = req.ConfirmationId,
            confirmationId = effectiveConfirmationId,
            confirmationKey,
            keyResolvedFromList,
            idResolvedFromList,
            matchedBy,
            session = new
            {
                steamId = account.Session.SteamID,
                accessToken = account.Session.AccessToken,
                refreshToken = account.Session.RefreshToken,
                sessionId = account.Session.SessionID,
                accessTokenRefreshed
            }
        };

        http.Response.ContentType = "application/json";
        await http.Response.WriteAsync(JsonConvert.SerializeObject(resp));
    }
    catch (Exception ex)
    {
        http.Response.StatusCode = 500;
        await http.Response.WriteAsync("operate confirmation failed: " + ex.Message);
    }
});

app.Run();

async Task<LoginRequest?> GetRequestBodyAsync(HttpContext http)
{
    try
    {
        using var sr = new StreamReader(http.Request.Body);
        var body = await sr.ReadToEndAsync();
        if (string.IsNullOrWhiteSpace(body)) return null;
        return JsonConvert.DeserializeObject<LoginRequest>(body);
    }
    catch
    {
        return null;
    }
}

async Task<WalletBalanceRequest?> GetWalletBalanceRequestBodyAsync(HttpContext http)
{
    try
    {
        using var sr = new StreamReader(http.Request.Body);
        var body = await sr.ReadToEndAsync();
        if (string.IsNullOrWhiteSpace(body)) return null;
        return JsonConvert.DeserializeObject<WalletBalanceRequest>(body);
    }
    catch
    {
        return null;
    }
}

async Task<TradeConfirmationsListRequest?> GetTradeConfirmationsListRequestBodyAsync(HttpContext http)
{
    try
    {
        using var sr = new StreamReader(http.Request.Body);
        var body = await sr.ReadToEndAsync();
        if (string.IsNullOrWhiteSpace(body)) return null;
        return JsonConvert.DeserializeObject<TradeConfirmationsListRequest>(body);
    }
    catch
    {
        return null;
    }
}

async Task<TradeConfirmationOperateRequest?> GetTradeConfirmationOperateRequestBodyAsync(HttpContext http)
{
    try
    {
        using var sr = new StreamReader(http.Request.Body);
        var body = await sr.ReadToEndAsync();
        if (string.IsNullOrWhiteSpace(body)) return null;
        return JsonConvert.DeserializeObject<TradeConfirmationOperateRequest>(body);
    }
    catch
    {
        return null;
    }
}

async Task<SteamGuardAccount?> BuildAccountWithSessionAsync(string maFilePath, SessionPayload sessionPayload)
{
    var contents = await File.ReadAllTextAsync(maFilePath);
    var account = JsonConvert.DeserializeObject<SteamGuardAccount>(contents);
    if (account == null)
    {
        return null;
    }

    if (string.IsNullOrWhiteSpace(account.DeviceID))
    {
        throw new Exception("maFile missing device_id");
    }

    account.Session = new SessionData
    {
        SteamID = sessionPayload.SteamId,
        AccessToken = sessionPayload.AccessToken,
        RefreshToken = sessionPayload.RefreshToken,
        SessionID = sessionPayload.SessionId
    };
    return account;
}

SteamClient CreateSteamClient(string? requestProxyUrl, ILogger logger, string endpointName)
{
    var (proxyUrl, source) = ResolveProxyUrl(requestProxyUrl);
    logger.LogInformation(
        "[{Endpoint}] Proxy resolved. source={Source}, value={Proxy}",
        endpointName,
        source,
        MaskProxyUrlForLog(proxyUrl)
    );

    if (string.IsNullOrWhiteSpace(proxyUrl))
    {
        logger.LogInformation("[{Endpoint}] Proxy disabled for this request.", endpointName);
        return new SteamClient();
    }

    if (!Uri.TryCreate(proxyUrl, UriKind.Absolute, out var proxyUri))
    {
        logger.LogWarning(
            "[{Endpoint}] Proxy url invalid. raw={RawProxy}",
            endpointName,
            MaskProxyUrlForLog(proxyUrl)
        );
        throw new ArgumentException("invalid proxy url, expected format like http://127.0.0.1:7890");
    }

    var config = SteamConfiguration.Create(builder =>
    {
        // Force WebSocket so proxy can be applied through HttpClient.
        builder.WithProtocolTypes(ProtocolTypes.WebSocket);
        builder.WithHttpClientFactory(() =>
        {
            var handler = new HttpClientHandler
            {
                Proxy = new WebProxy(proxyUri),
                UseProxy = true
            };
            return new HttpClient(handler, disposeHandler: true);
        });
    });

    return new SteamClient(config);
}

HttpClientHandler CreateHttpClientHandler(string? requestProxyUrl, ILogger logger, string endpointName)
{
    var (proxyUrl, source) = ResolveProxyUrl(requestProxyUrl);
    logger.LogInformation(
        "[{Endpoint}] Proxy resolved. source={Source}, value={Proxy}",
        endpointName,
        source,
        MaskProxyUrlForLog(proxyUrl)
    );

    var handler = new HttpClientHandler();
    if (string.IsNullOrWhiteSpace(proxyUrl))
    {
        logger.LogInformation("[{Endpoint}] Proxy disabled for this request.", endpointName);
        return handler;
    }

    if (!Uri.TryCreate(proxyUrl, UriKind.Absolute, out var proxyUri))
    {
        logger.LogWarning(
            "[{Endpoint}] Proxy url invalid. raw={RawProxy}",
            endpointName,
            MaskProxyUrlForLog(proxyUrl)
        );
        throw new ArgumentException("invalid proxy url, expected format like http://127.0.0.1:7890");
    }

    handler.Proxy = new WebProxy(proxyUri);
    handler.UseProxy = true;
    return handler;
}

(string? ProxyUrl, string Source) ResolveProxyUrl(string? requestProxyUrl)
{
    if (!string.IsNullOrWhiteSpace(requestProxyUrl))
    {
        return (requestProxyUrl, "request.ProxyUrl");
    }

    var envProxy = Environment.GetEnvironmentVariable("STEAM_PROXY_URL");
    if (!string.IsNullOrWhiteSpace(envProxy))
    {
        return (envProxy, "env.STEAM_PROXY_URL");
    }

    return (null, "none");
}

string MaskProxyUrlForLog(string? proxyUrl)
{
    if (string.IsNullOrWhiteSpace(proxyUrl))
    {
        return "<none>";
    }

    if (!Uri.TryCreate(proxyUrl, UriKind.Absolute, out var uri))
    {
        var trimmed = proxyUrl.Trim();
        if (trimmed.Length > 64)
        {
            trimmed = trimmed.Substring(0, 64) + "...";
        }
        return $"<invalid:{trimmed}>";
    }

    var hostPort = uri.IsDefaultPort ? uri.Host : $"{uri.Host}:{uri.Port}";
    return $"{uri.Scheme}://{hostPort}";
}

record LoginRequest(string Username, string Password, string MaFilePath, string? ProxyUrl = null);
record WalletBalanceRequest(string SteamLoginSecure, string? ProxyUrl = null);
record TradeConfirmationsListRequest(string MaFilePath, SessionPayload Session, string? ProxyUrl = null);
record TradeConfirmationOperateRequest(
    string MaFilePath,
    SessionPayload Session,
    ulong ConfirmationId,
    ulong? ConfirmationKey,
    string Operation,
    string? ProxyUrl = null
);
record SessionPayload(ulong SteamId, string AccessToken, string RefreshToken, string? SessionId = null);

internal class FileAuthenticator : IAuthenticator
{
    private readonly SteamGuardAccount? account;
    private int deviceCodesGenerated = 0;

    public FileAuthenticator(SteamGuardAccount? account)
    {
        this.account = account;
    }

    public Task<bool> AcceptDeviceConfirmationAsync()
    {
        return Task.FromResult(false);
    }

    public async Task<string> GetDeviceCodeAsync(bool previousCodeWasIncorrect)
    {
        if (previousCodeWasIncorrect)
        {
            if (deviceCodesGenerated > 2)
                throw new Exception("failed to generate device code from maFile");
            await Task.Delay(30000);
        }

        if (account == null) return null;
        deviceCodesGenerated++;
        var code = await account.GenerateSteamGuardCodeAsync();
        return code ?? "";
    }

    public Task<string> GetEmailCodeAsync(string email, bool previousCodeWasIncorrect)
    {
        // This implementation does not support interactive email codes.
        return Task.FromResult(string.Empty);
    }
}