using System.Text;
using EasyCaching.Core;
using Furion.DependencyInjection;
using Furion.FriendlyException;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Newtonsoft.Json;
using YD_Event.Core.Options;

namespace YD_Event.Core.Infrastructure.WeChat;

/// <summary>
/// 微信小程序码服务，与登录服务隔离，避免制码故障影响现有登录链路。
/// </summary>
public class WeChatMiniProgramCodeService : ITransient
{
    private readonly IHttpClientFactory _httpClientFactory;
    private readonly ILogger<WeChatMiniProgramCodeService> _logger;
    private readonly WeChatOptions _options;
    private readonly IEasyCachingProvider _cache;

    private string AccessTokenCacheKey => $"wechat:mini-program:access-token:{_options.AppId}";

    public WeChatMiniProgramCodeService(IHttpClientFactory httpClientFactory,
        ILogger<WeChatMiniProgramCodeService> logger, IOptions<WeChatOptions> options,
        IEasyCachingProvider cache)
    {
        _httpClientFactory = httpClientFactory;
        _logger = logger;
        _options = options.Value;
        _cache = cache;
    }

    public async Task<byte[]> GenerateAsync(string scene, string page, int width = 430)
    {
        if (string.IsNullOrWhiteSpace(scene) || Encoding.UTF8.GetByteCount(scene) > 32)
            throw Oops.Bah("小程序码参数无效");
        if (string.IsNullOrWhiteSpace(page)) throw Oops.Bah("小程序页面路径不能为空");
        if (string.IsNullOrWhiteSpace(_options.AppId) || string.IsNullOrWhiteSpace(_options.Secret))
            throw Oops.Bah("微信小程序配置不完整");

        using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(15));
        try
        {
            return await GenerateAsync(scene, page, width, false, timeout.Token);
        }
        catch (OperationCanceledException) when (timeout.IsCancellationRequested)
        {
            _logger.LogError("WeChat mini program code request timed out after 15 seconds");
            throw Oops.Bah("微信小程序码服务请求超时，请稍后重试");
        }
        catch (HttpRequestException exception)
        {
            _logger.LogError("WeChat mini program code network error: {ErrorType}, {ErrorMessage}",
                exception.GetType().Name, exception.Message);
            throw Oops.Bah("微信小程序码服务网络异常，请稍后重试");
        }
    }

    private async Task<byte[]> GenerateAsync(string scene, string page, int width,
        bool forceRefreshToken, CancellationToken cancellationToken)
    {
        var accessToken = await GetAccessTokenAsync(forceRefreshToken, cancellationToken);
        var client = _httpClientFactory.CreateClient();
        var requestBody = JsonConvert.SerializeObject(new
        {
            scene,
            page,
            width,
            check_path = true,
            env_version = NormalizeEnvVersion(_options.MiniProgramEnvVersion)
        });
        using var requestContent = new StringContent(requestBody, Encoding.UTF8, "application/json");
        using var response = await client.PostAsync(
            $"https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token={Uri.EscapeDataString(accessToken)}",
            requestContent, cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            var errorBody = await response.Content.ReadAsStringAsync(cancellationToken);
            _logger.LogError(
                "WeChat mini program code HTTP error: {StatusCode}, Page: {Page}, EnvVersion: {EnvVersion}, Body: {ErrorBody}",
                response.StatusCode, page, NormalizeEnvVersion(_options.MiniProgramEnvVersion), LimitLogContent(errorBody));

            throw Oops.Bah("微信小程序码服务暂不可用，请稍后重试");
        }

        var bytes = await response.Content.ReadAsByteArrayAsync(cancellationToken);
        var mediaType = response.Content.Headers.ContentType?.MediaType;
        if (mediaType?.StartsWith("image/", StringComparison.OrdinalIgnoreCase) == true || IsJpeg(bytes))
            return bytes;

        var errorJson = Encoding.UTF8.GetString(bytes);
        WeChatApiError? error = null;
        try
        {
            error = JsonConvert.DeserializeObject<WeChatApiError>(errorJson);
        }
        catch (JsonException)
        {
            // 非微信标准错误体，统一按服务异常处理，原文只写入服务端日志。
        }

        if (!forceRefreshToken && error?.ErrCode is 40001 or 40014 or 42001)
        {
            await _cache.RemoveAsync(AccessTokenCacheKey);
            return await GenerateAsync(scene, page, width, true, cancellationToken);
        }

        _logger.LogError("WeChat mini program code error: {Error}", LimitLogContent(errorJson));
        throw Oops.Bah("微信小程序码生成失败，请稍后重试");
    }

    private async Task<string> GetAccessTokenAsync(bool forceRefresh, CancellationToken cancellationToken)
    {
        if (!forceRefresh)
        {
            var cached = await _cache.GetAsync<string>(AccessTokenCacheKey);
            if (cached.HasValue && !string.IsNullOrWhiteSpace(cached.Value)) return cached.Value;
        }

        var client = _httpClientFactory.CreateClient();
        var url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential" +
                  $"&appid={Uri.EscapeDataString(_options.AppId)}&secret={Uri.EscapeDataString(_options.Secret)}";
        using var response = await client.GetAsync(url, cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            var errorBody = await response.Content.ReadAsStringAsync(cancellationToken);
            _logger.LogError("WeChat access token HTTP error: {StatusCode}, Body: {ErrorBody}",
                response.StatusCode, LimitLogContent(errorBody));
            throw Oops.Bah("微信服务暂不可用，请稍后重试");
        }

        var json = await response.Content.ReadAsStringAsync(cancellationToken);
        var token = JsonConvert.DeserializeObject<WeChatAccessTokenResponse>(json);
        if (token == null || string.IsNullOrWhiteSpace(token.AccessToken))
        {
            _logger.LogError("WeChat access token error: {Error}", LimitLogContent(json));
            throw Oops.Bah("微信访问凭证获取失败，请检查小程序配置");
        }

        await _cache.SetAsync(AccessTokenCacheKey, token.AccessToken,
            TimeSpan.FromSeconds(Math.Max(60, token.ExpiresIn - 300)));
        return token.AccessToken;
    }

    private static bool IsJpeg(byte[] bytes) => bytes.Length >= 3
        && bytes[0] == 0xFF && bytes[1] == 0xD8 && bytes[2] == 0xFF;

    private static string NormalizeEnvVersion(string? envVersion) => envVersion?.Trim().ToLowerInvariant() switch
    {
        "develop" => "develop",
        "trial" => "trial",
        null or "" or "release" => "release",
        _ => throw Oops.Bah("微信小程序码版本配置无效，仅支持 develop、trial 或 release")
    };

    private static string LimitLogContent(string content) => content.Length <= 4096
        ? content
        : $"{content[..4096]}...(truncated)";

    private sealed class WeChatAccessTokenResponse : WeChatApiError
    {
        [JsonProperty("access_token")]
        public string? AccessToken { get; set; }

        [JsonProperty("expires_in")]
        public int ExpiresIn { get; set; }
    }

    private class WeChatApiError
    {
        [JsonProperty("errcode")]
        public int ErrCode { get; set; }

        [JsonProperty("errmsg")]
        public string? ErrMsg { get; set; }
    }
}