using Fake.Application;
using Microsoft.AspNetCore.Mvc;
using SimpleAdmin.Api.WeChat.Options;
using SimpleAdmin.Api.WeChat.Services;

namespace SimpleAdmin.Api.WeChat;

internal static class WeChatMpCallbackSupport
{
    /// <summary>
    /// 微信 GET 接入验签：从 Query 读取参数，验签通过后原样输出 echostr。
    /// </summary>
    public static bool TryValidateGetRequest(
        WeChatMpOptions options,
        HttpRequest request,
        ILogger? logger,
        out string echostr)
    {
        echostr = string.Empty;

        if (string.IsNullOrWhiteSpace(options.Token))
        {
            logger?.LogWarning("微信 GET 验签失败：未配置 Token");
            return false;
        }

        var signature = request.Query["signature"].ToString();
        var timestamp = request.Query["timestamp"].ToString();
        var nonce = request.Query["nonce"].ToString();
        echostr = request.Query["echostr"].ToString();

        if (string.IsNullOrWhiteSpace(signature)
            || string.IsNullOrWhiteSpace(timestamp)
            || string.IsNullOrWhiteSpace(nonce)
            || string.IsNullOrEmpty(echostr))
        {
            logger?.LogWarning(
                "微信 GET 验签失败：缺少必要参数 signature={HasSig} timestamp={HasTs} nonce={HasNonce} echostr={HasEcho}",
                !string.IsNullOrWhiteSpace(signature),
                !string.IsNullOrWhiteSpace(timestamp),
                !string.IsNullOrWhiteSpace(nonce),
                !string.IsNullOrEmpty(echostr));
            return false;
        }

        if (!WeChatSignatureHelper.Validate(options.Token, timestamp, nonce, signature))
        {
            logger?.LogWarning(
                "微信 GET 验签失败：signature 不匹配 timestamp={Timestamp} nonce={Nonce}",
                timestamp,
                nonce);
            return false;
        }

        return true;
    }

    public static ContentResult Validate(
        WeChatMpOptions options,
        HttpRequest request,
        string? signature,
        string? timestamp,
        string? nonce)
    {
        if (!TryValidateGetRequest(options, request, null, out var echostr))
        {
            return PlainError();
        }

        return EchoStr(echostr);
    }

    /// <summary>微信或探活可能发 HEAD，须返回 200（WMS/Spring 默认支持）。</summary>
    public static ContentResult HeadOk() =>
        new() { Content = string.Empty, ContentType = "text/plain; charset=utf-8", StatusCode = StatusCodes.Status200OK };

    public static ContentResult PlainError() => PlainText("error");

    public static async Task<ContentResult> HandleMessageAsync(
        WeChatMpOptions options,
        IWeChatEventHandler eventHandler,
        HttpRequest request,
        ILogger logger,
        string signature,
        string timestamp,
        string nonce,
        string? encryptType,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(options.Token))
        {
            logger.LogWarning("微信消息回调未配置 Token");
            return PlainText("error");
        }

        // token、timestamp、nonce 字典序排序后拼接，SHA1 与 signature 对比
        if (!WeChatSignatureHelper.Validate(options.Token, timestamp, nonce, signature))
        {
            logger.LogWarning("微信消息验签失败");
            return PlainText("error");
        }

        using var reader = new StreamReader(request.Body);
        var requestBody = await reader.ReadToEndAsync(cancellationToken);
        if (string.IsNullOrWhiteSpace(requestBody))
        {
            return AckSuccess();
        }

        // 明文模式：无 encrypt_type 或 encrypt_type=raw；安全模式 AES 暂不支持
        if (!string.IsNullOrWhiteSpace(encryptType)
            && !string.Equals(encryptType, "raw", StringComparison.OrdinalIgnoreCase))
        {
            logger.LogWarning(
                "收到加密微信消息({EncryptType})，当前仅支持明文模式，请在公众平台切换为明文或后续启用 AES。",
                encryptType);
            return AckSuccess();
        }

        var message = WeChatIncomingMessageParser.Parse(requestBody, request.ContentType);
        if (message == null)
        {
            logger.LogWarning("无法解析微信消息体（支持明文 XML / JSON）");
            return AckSuccess();
        }

        var reply = await eventHandler.HandleAsync(message, cancellationToken);
        return BuildMessageReply(reply);
    }

    public static void EnsureAppId(WeChatMpOptions options, string appId)
    {
        var configured = options.AppId;
        if (string.IsNullOrWhiteSpace(configured))
        {
            throw new BusinessException("未配置微信公众号 AppId");
        }

        if (!string.Equals(configured, appId, StringComparison.OrdinalIgnoreCase))
        {
            throw new BusinessException("公众号 AppId 不匹配");
        }
    }

    private static ContentResult EchoStr(string echostr) =>
        new() { Content = echostr, ContentType = "text/plain", StatusCode = StatusCodes.Status200OK };

    private static ContentResult AckSuccess() => PlainText("success");

    private static ContentResult BuildMessageReply(string? reply)
    {
        if (string.IsNullOrEmpty(reply))
        {
            return AckSuccess();
        }

        return reply.TrimStart().StartsWith('<') ? Xml(reply) : PlainText(reply);
    }

    private static ContentResult PlainText(string content) =>
        new() { Content = content, ContentType = "text/plain; charset=utf-8", StatusCode = StatusCodes.Status200OK };

    private static ContentResult Xml(string content) =>
        new() { Content = content, ContentType = "application/xml; charset=utf-8", StatusCode = StatusCodes.Status200OK };
}