using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using UnityEngine;
using UnityEngine.Networking;

namespace NBF
{
    /// <summary>
    /// UnityWebRequest GET/POST 工具类：
    /// - GET（query 参数）
    /// - POST JSON
    /// - POST 表单（x-www-form-urlencoded / multipart）
    /// - 上传文件（multipart）
    /// - 自定义 Header
    /// - 超时、取消
    /// - 统一返回文本 / 原始字节
    /// </summary>
    public static class HttpUtil
    {
        // ========== 公共返回结构 ==========
        public readonly struct HttpResult
        {
            public readonly bool ok;
            public readonly long statusCode;
            public readonly string text;
            public readonly byte[] data;
            public readonly string error; // 包含网络错误/HTTP错误/取消/超时等信息
            public readonly Dictionary<string, string> responseHeaders;

            public HttpResult(bool ok, long statusCode, string text, byte[] data, string error,
                Dictionary<string, string> responseHeaders)
            {
                this.ok = ok;
                this.statusCode = statusCode;
                this.text = text;
                this.data = data;
                this.error = error;
                this.responseHeaders = responseHeaders;
            }

            public override string ToString() =>
                $"ok={ok}, status={statusCode}, error={error}, textLen={text?.Length ?? 0}";
        }

        /// <summary>
        /// 用于取消请求（调用 Cancel() 会中止 UnityWebRequest）
        /// </summary>
        public sealed class RequestHandle
        {
            internal UnityWebRequest req;
            public bool IsDone => req == null || req.isDone;

            public void Cancel()
            {
                try
                {
                    req?.Abort();
                }
                catch
                {
                    /* ignore */
                }
            }
        }

        // ========== 对外 API（协程） ==========

        public static IEnumerator Get(
            string url,
            Dictionary<string, string> query = null,
            Dictionary<string, string> headers = null,
            int timeoutSeconds = 15,
            Action<HttpResult> callback = null,
            RequestHandle handle = null)
        {
            var finalUrl = BuildUrlWithQuery(url, query);

            using (var req = UnityWebRequest.Get(finalUrl))
            {
                ApplyCommon(req, headers, timeoutSeconds, handle);

                yield return req.SendWebRequest();

                callback?.Invoke(BuildResult(req));
            }
        }

        /// <summary>
        /// POST JSON（Content-Type: application/json）
        /// </summary>
        public static IEnumerator PostJson(
            string url,
            string jsonBody,
            Dictionary<string, string> headers = null,
            int timeoutSeconds = 15,
            Action<HttpResult> callback = null,
            RequestHandle handle = null)
        {
            var bodyBytes = string.IsNullOrEmpty(jsonBody) ? Array.Empty<byte>() : Encoding.UTF8.GetBytes(jsonBody);

            using (var req = new UnityWebRequest(url, UnityWebRequest.kHttpVerbPOST))
            {
                req.uploadHandler = new UploadHandlerRaw(bodyBytes);
                req.downloadHandler = new DownloadHandlerBuffer();
                req.SetRequestHeader("Content-Type", "application/json; charset=utf-8");

                ApplyCommon(req, headers, timeoutSeconds, handle);

                yield return req.SendWebRequest();

                callback?.Invoke(BuildResult(req));
            }
        }

        /// <summary>
        /// POST 表单（application/x-www-form-urlencoded）
        /// </summary>
        public static IEnumerator PostFormUrlEncoded(
            string url,
            Dictionary<string, string> form,
            Dictionary<string, string> headers = null,
            int timeoutSeconds = 15,
            Action<HttpResult> callback = null,
            RequestHandle handle = null)
        {
            // Unity 内部会自动按 x-www-form-urlencoded 处理字段
            var formData = new List<IMultipartFormSection>();
            if (form != null)
            {
                foreach (var kv in form)
                    formData.Add(new MultipartFormDataSection(kv.Key, kv.Value));
            }

            // 这里用 Post + 手动覆盖 content-type
            using (var req = UnityWebRequest.Post(url, formData))
            {
                req.downloadHandler = new DownloadHandlerBuffer();
                req.SetRequestHeader("Content-Type", "application/x-www-form-urlencoded; charset=utf-8");

                ApplyCommon(req, headers, timeoutSeconds, handle);

                yield return req.SendWebRequest();

                callback?.Invoke(BuildResult(req));
            }
        }

        /// <summary>
        /// POST multipart（可用于普通表单 + 文件上传）
        /// files: (fieldName, fileName, bytes, mimeType)
        /// </summary>
        public static IEnumerator PostMultipart(
            string url,
            Dictionary<string, string> fields,
            List<(string fieldName, string fileName, byte[] bytes, string mimeType)> files,
            Dictionary<string, string> headers = null,
            int timeoutSeconds = 30,
            Action<HttpResult> callback = null,
            RequestHandle handle = null)
        {
            var form = new List<IMultipartFormSection>();

            if (fields != null)
            {
                foreach (var kv in fields)
                    form.Add(new MultipartFormDataSection(kv.Key, kv.Value));
            }

            if (files != null)
            {
                foreach (var f in files)
                {
                    var mime = string.IsNullOrEmpty(f.mimeType) ? "application/octet-stream" : f.mimeType;
                    form.Add(new MultipartFormFileSection(f.fieldName, f.bytes, f.fileName, mime));
                }
            }

            using (var req = UnityWebRequest.Post(url, form))
            {
                req.downloadHandler = new DownloadHandlerBuffer();
                ApplyCommon(req, headers, timeoutSeconds, handle);

                yield return req.SendWebRequest();

                callback?.Invoke(BuildResult(req));
            }
        }

        /// <summary>
        /// 下载二进制（比如图片、ab、配置包等）
        /// </summary>
        public static IEnumerator GetBytes(
            string url,
            Dictionary<string, string> query = null,
            Dictionary<string, string> headers = null,
            int timeoutSeconds = 30,
            Action<HttpResult> callback = null,
            RequestHandle handle = null)
        {
            var finalUrl = BuildUrlWithQuery(url, query);

            using (var req = UnityWebRequest.Get(finalUrl))
            {
                req.downloadHandler = new DownloadHandlerBuffer();
                ApplyCommon(req, headers, timeoutSeconds, handle);

                yield return req.SendWebRequest();

                callback?.Invoke(BuildResult(req, preferBytes: true));
            }
        }

        // ========== 便捷：返回 JSON 反序列化（JsonUtility） ==========
        // 注意：JsonUtility 不支持 Dictionary / 顶层数组等，你若需要更强建议用 Newtonsoft.Json
        public static IEnumerator GetJson<T>(
            string url,
            Dictionary<string, string> query = null,
            Dictionary<string, string> headers = null,
            int timeoutSeconds = 15,
            Action<bool, T, HttpResult> callback = null,
            RequestHandle handle = null)
        {
            yield return Get(url, query, headers, timeoutSeconds, r =>
            {
                if (!r.ok)
                {
                    callback?.Invoke(false, default, r);
                    return;
                }

                try
                {
                    var obj = JsonUtility.FromJson<T>(r.text);
                    callback?.Invoke(true, obj, r);
                }
                catch (Exception e)
                {
                    callback?.Invoke(false, default, new HttpResult(false, r.statusCode, r.text, r.data,
                        "JSON parse error: " + e.Message, r.responseHeaders));
                }
            }, handle);
        }

        // ========== 内部工具 ==========
        static void ApplyCommon(UnityWebRequest req, Dictionary<string, string> headers, int timeoutSeconds,
            RequestHandle handle)
        {
            req.timeout = Mathf.Max(1, timeoutSeconds);
            req.downloadHandler ??= new DownloadHandlerBuffer();

            if (headers != null)
            {
                foreach (var kv in headers)
                {
                    if (!string.IsNullOrEmpty(kv.Key))
                        req.SetRequestHeader(kv.Key, kv.Value);
                }
            }

            if (handle != null) handle.req = req;
        }

        static HttpResult BuildResult(UnityWebRequest req, bool preferBytes = false)
        {
            // Unity 2020+ : result enum
            bool isNetworkOrHttpError =
                req.result == UnityWebRequest.Result.ConnectionError ||
                req.result == UnityWebRequest.Result.ProtocolError ||
                req.result == UnityWebRequest.Result.DataProcessingError;

            var code = req.responseCode;
            var headers = req.GetResponseHeaders();

            // 下载内容
            byte[] data = null;
            string text = null;

            if (req.downloadHandler != null)
            {
                data = req.downloadHandler.data;

                // preferBytes==false 时优先给 text
                if (!preferBytes)
                {
                    try
                    {
                        text = req.downloadHandler.text;
                    }
                    catch
                    {
                        text = data != null ? Encoding.UTF8.GetString(data) : null;
                    }
                }
                else
                {
                    // preferBytes==true 时 text 也尽量给一份（方便日志）
                    try
                    {
                        text = req.downloadHandler.text;
                    }
                    catch
                    {
                        /* ignore */
                    }
                }
            }

            // 错误信息（包含 HTTP 错误）
            string err = null;
            if (isNetworkOrHttpError)
            {
                err = req.error;
                // 有些后端会把错误细节放在 body
                if (!string.IsNullOrEmpty(text))
                    err = $"{err}\nBody: {TrimForLog(text, 1200)}";
            }

            bool ok = !isNetworkOrHttpError && code >= 200 && code < 300;

            return new HttpResult(ok, code, text, data, err, headers);
        }

        static string BuildUrlWithQuery(string url, Dictionary<string, string> query)
        {
            if (query == null || query.Count == 0) return url;

            var sb = new StringBuilder(url);
            sb.Append(url.Contains("?") ? "&" : "?");

            bool first = true;
            foreach (var kv in query)
            {
                if (!first) sb.Append('&');
                first = false;

                sb.Append(UnityWebRequest.EscapeURL(kv.Key));
                sb.Append('=');
                sb.Append(UnityWebRequest.EscapeURL(kv.Value ?? ""));
            }

            return sb.ToString();
        }

        static string TrimForLog(string s, int maxLen)
        {
            if (string.IsNullOrEmpty(s)) return s;
            if (s.Length <= maxLen) return s;
            return s.Substring(0, maxLen) + "...(truncated)";
        }
    }
}