using System.Text.Json;

namespace AgriculturalPlatform.Api.Services;

/// <summary>
/// 阿里云市场身份证 OCR 识别服务。
/// 接口：POST https://swcardpack.market.alicloudapi.com/ocr/idcard
/// 认证：请求头 Authorization: APPCODE &lt;AppCode&gt;（无需 AppKey/AppSecret）
/// 传输：优先 image_url（OSS 私有桶 10 分钟签名 URL，实测兼容性最好）；
///       本地存储或签名失败时回退 image_base64。
/// 返回：result 容器（兼容 data），成功码 0000/1000/0/200 等；
///       正面字段 name/number/sex/address，反面 authority/valid_date，字段名做多别名兼容。
/// 配置：appsettings.json 的 Ocr 节点（Provider=aliyun、AppCode、Url、MaxBytes）。
/// </summary>
public sealed class AliyunOcrService(IConfiguration cfg, IHttpClientFactory httpFactory, IFileStorage storage) : IOcrService
{
    public async Task<IdCardOcrResult> RecognizeAsync(Stream image, string side, string fileName = "idcard.jpg", string? storageKey = null)
    {
        var appCode = cfg["Ocr:AppCode"];
        var url = cfg["Ocr:Url"] ?? "https://swcardpack.market.alicloudapi.com/ocr/idcard";
        if (string.IsNullOrWhiteSpace(appCode))
            return new IdCardOcrResult(Success: false,
                Message: "未配置阿里云 OCR AppCode（appsettings.json 的 Ocr:AppCode）");

        var client = httpFactory.CreateClient("ocr");

        // 方式一：image_url（OSS 签名 URL），可绕过接口对 base64 的兼容问题
        if (!string.IsNullOrWhiteSpace(storageKey))
        {
            var presigned = storage.GeneratePresignedUrl(storageKey);
            if (!string.IsNullOrWhiteSpace(presigned))
            {
                using var req = new HttpRequestMessage(HttpMethod.Post, url)
                {
                    Content = new FormUrlEncodedContent(new Dictionary<string, string> { ["image_url"] = presigned })
                };
                req.Headers.TryAddWithoutValidation("Authorization", $"APPCODE {appCode}");
                try
                {
                    using var resp = await client.SendAsync(req);
                    var body = await resp.Content.ReadAsStringAsync();
                    if (resp.IsSuccessStatusCode) return ParseResult(body, side);
                    if (!TryParseResult(body, out var r)) // 业务层报错（8888 等）也透传给用户
                        return r;
                }
                catch (Exception ex)
                {
                    return new IdCardOcrResult(Success: false, Message: $"OCR 调用异常（image_url）：{ex.Message}");
                }
            }
        }

        // 方式二：image_base64 回退
        if (image.CanSeek) image.Position = 0;
        await using var buffer = new MemoryStream();
        await image.CopyToAsync(buffer);

        var maxBytes = cfg.GetValue("Ocr:MaxBytes", 4L * 1024 * 1024);
        if (buffer.Length > maxBytes)
            return new IdCardOcrResult(Success: false, Message: "图片过大（超过 4MB），请压缩后重试");

        var base64 = Convert.ToBase64String(buffer.ToArray());
        using var req2 = new HttpRequestMessage(HttpMethod.Post, url)
        {
            Content = new FormUrlEncodedContent(new Dictionary<string, string> { ["image_base64"] = base64 })
        };
        req2.Headers.TryAddWithoutValidation("Authorization", $"APPCODE {appCode}");

        try
        {
            using var resp2 = await client.SendAsync(req2);
            var body2 = await resp2.Content.ReadAsStringAsync();
            if (!resp2.IsSuccessStatusCode)
                return new IdCardOcrResult(Success: false,
                    Message: $"OCR 接口返回 HTTP {(int)resp2.StatusCode}：{Truncate(body2, 200)}");
            return ParseResult(body2, side);
        }
        catch (Exception ex)
        {
            return new IdCardOcrResult(Success: false, Message: $"OCR 调用异常：{ex.Message}");
        }
    }

    /// <summary>尝试解析接口返回；无法解析出 JSON 时返回 false</summary>
    private static bool TryParseResult(string json, out IdCardOcrResult result)
    {
        try
        {
            using var doc = JsonDocument.Parse(json);
            result = ParseDoc(doc.RootElement, "");
            return true;
        }
        catch (JsonException)
        {
            result = new IdCardOcrResult(Success: false, Message: "OCR 返回数据无法解析");
            return false;
        }
    }

    /// <summary>解析接口返回 JSON（兼容 result/data 容器、多字段别名）</summary>
    private static IdCardOcrResult ParseResult(string json, string side)
    {
        try
        {
            using var doc = JsonDocument.Parse(json);
            return ParseDoc(doc.RootElement, side);
        }
        catch (JsonException)
        {
            return new IdCardOcrResult(Success: false, Message: "OCR 返回数据无法解析");
        }
    }

    private static IdCardOcrResult ParseDoc(JsonElement root, string side)
    {
        var data = root;
        if (root.ValueKind == JsonValueKind.Object)
        {
            if (root.TryGetProperty("result", out var r) && r.ValueKind == JsonValueKind.Object)
                data = r;
            else if (root.TryGetProperty("data", out var d) && d.ValueKind == JsonValueKind.Object)
                data = d;
        }

        // 接口级失败判定（success=false 或 result_code/code 非成功码）
        var ok = GetBool(root, "success") ?? GetBool(root, "ok") ?? true;
        var code = GetStr(root, "result_code") ?? GetStr(root, "code") ?? GetStr(root, "status") ?? "";
        var msg = GetStr(root, "result_msg") ?? GetStr(root, "msg")
            ?? GetStr(root, "message") ?? GetStr(root, "errmsg") ?? "";
        if (!ok && !IsSuccessCode(code))
            return new IdCardOcrResult(Success: false,
                Message: string.IsNullOrWhiteSpace(msg) ? $"OCR 识别失败（code={code}）" : $"{msg}（code={code}）");

        var name = GetFirst(data, "name", "realName", "trueName", "姓名");
        var idCard = GetFirst(data, "number", "id", "idCard", "idNumber", "cardNo", "num", "身份证号");
        var gender = NormalizeGender(GetFirst(data, "sex", "gender", "性别"));
        var address = GetFirst(data, "address", "addr", "住址");
        var authority = GetFirst(data, "authority", "issuingAuthority", "issueOrg", "signOrg", "签发机关");
        var validDate = GetFirst(data, "valid_date", "validDate", "validity", "expiry", "有效期");

        // 正面看姓名/证件号，反面看签发机关/有效期；任一命中即视为识别成功
        var success = side == "back"
            ? !string.IsNullOrWhiteSpace(authority) || !string.IsNullOrWhiteSpace(validDate)
            : !string.IsNullOrWhiteSpace(name) || !string.IsNullOrWhiteSpace(idCard);

        return new IdCardOcrResult(
            name, idCard, gender, address, "", "",
            success, success ? "识别完成" : "未识别到有效信息，请确保图片清晰、证件完整");
    }

    private static bool IsSuccessCode(string code) =>
        code is "0000" or "0" or "200" or "1000" or "000000" or "1";

    private static bool? GetBool(JsonElement e, string key) =>
        e.ValueKind == JsonValueKind.Object && e.TryGetProperty(key, out var v)
            ? v.ValueKind switch
            {
                JsonValueKind.True => true,
                JsonValueKind.False => false,
                JsonValueKind.String when bool.TryParse(v.GetString(), out var b) => b,
                _ => null
            }
            : null;

    private static string? GetStr(JsonElement e, string key) =>
        e.ValueKind == JsonValueKind.Object && e.TryGetProperty(key, out var v) && v.ValueKind == JsonValueKind.String
            ? v.GetString()
            : null;

    private static string GetFirst(JsonElement e, params string[] keys)
    {
        if (e.ValueKind != JsonValueKind.Object) return "";
        foreach (var k in keys)
            if (e.TryGetProperty(k, out var v) && v.ValueKind is JsonValueKind.String)
            {
                var s = v.GetString()?.Trim();
                if (!string.IsNullOrWhiteSpace(s)) return s!;
            }
        return "";
    }

    private static string NormalizeGender(string? v) => v switch
    {
        null or "" => "",
        "1" or "M" or "male" or "Male" or "男" => "男",
        "2" or "F" or "female" or "Female" or "女" => "女",
        _ => v
    };

    private static string Truncate(string s, int max) =>
        s.Length <= max ? s : s[..max] + "...";
}