package yuyuecha

import (
	"bytes"
	"context"
	"crypto/md5"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"strconv"
	"strings"
	"time"

	"tyapi-server/internal/shared/external_logger"
)

const (
	defaultRequestTimeout = 30 * time.Second
	maxLogResponseBodyLen = 500

	headerContentType = "Content-Type"
	contentTypeJSON   = "application/json"

	headerBillable         = "X-Billable"
	headerChargeFen        = "X-Charge-Fen"
	headerIdempotentReplay = "X-Idempotent-Replay"

	openAPIPrefix = "/openapi/v1"
	accountPath   = "/openapi/v1/account"
)

// ServiceConfig 愉悦查服务配置
type ServiceConfig struct {
	BaseURL      string
	ClientID     string
	ClientSecret string
	Timeout      time.Duration
	// Debug 开发环境开启时写入单一排查文件（curl + response），不重复打 request/response 日志
	Debug bool
	// DebugLogDir 排查日志目录，文件名为 dev_curl.log
	DebugLogDir string
}

// YuyuechaService 愉悦查 OpenAPI 客户端
type YuyuechaService struct {
	config ServiceConfig
	logger *external_logger.ExternalServiceLogger
}

// NewYuyuechaService 创建愉悦查服务实例
func NewYuyuechaService(cfg ServiceConfig, logger *external_logger.ExternalServiceLogger) *YuyuechaService {
	if cfg.Timeout == 0 {
		cfg.Timeout = defaultRequestTimeout
	}
	return &YuyuechaService{
		config: cfg,
		logger: logger,
	}
}

func (s *YuyuechaService) generateRequestID() string {
	timestamp := time.Now().UnixNano()
	hash := md5.Sum([]byte(fmt.Sprintf("%d_%s", timestamp, s.config.ClientID)))
	return fmt.Sprintf("yuyuecha_%x", hash[:8])
}

func truncateForLog(str string, maxLen int) string {
	if maxLen <= 0 || len(str) <= maxLen {
		return str
	}
	return str[:maxLen] + "...[truncated, total " + strconv.Itoa(len(str)) + " chars]"
}

// CallAPI 调用愉悦查业务 OpenAPI（POST）
// apiPath 为相对路径入参，如 a01/person-company-relations；服务内拼接为 /openapi/v1/{apiPath}
// body 会按紧凑 JSON（无空格、保留 Unicode）序列化后参与签名，务必与上游一致。
func (s *YuyuechaService) CallAPI(ctx context.Context, apiPath string, body map[string]interface{}) (*CallResult, error) {
	path := buildOpenAPIPath(apiPath)
	bodyBytes, err := json.Marshal(body)
	if err != nil {
		return nil, errors.Join(ErrSystem, fmt.Errorf("请求序列化失败: %w", err))
	}
	return s.doRequest(ctx, http.MethodPost, path, bodyBytes, body)
}

// buildOpenAPIPath 将相对 apiPath 拼成签名用完整 path：/openapi/v1/{apiPath}
func buildOpenAPIPath(apiPath string) string {
	apiPath = strings.TrimSpace(apiPath)
	apiPath = strings.TrimPrefix(apiPath, "/")
	if strings.HasPrefix(apiPath, "openapi/v1/") {
		return "/" + apiPath
	}
	return openAPIPrefix + "/" + apiPath
}

// GetAccount 查询账户汇总（GET /openapi/v1/account，请求体为空，签名 bodySha256 对 b""）
func (s *YuyuechaService) GetAccount(ctx context.Context) (*AccountInfo, error) {
	result, err := s.doRequest(ctx, http.MethodGet, accountPath, nil, nil)
	if err != nil {
		return nil, err
	}
	var info AccountInfo
	if err := json.Unmarshal(result.Data, &info); err != nil {
		return nil, errors.Join(ErrSystem, fmt.Errorf("账户响应解析失败: %w", err))
	}
	return &info, nil
}

func (s *YuyuechaService) doRequest(ctx context.Context, method, path string, bodyBytes []byte, logParams interface{}) (*CallResult, error) {
	startTime := time.Now()
	requestID := s.generateRequestID()

	var transactionID string
	if id, ok := ctx.Value("transaction_id").(string); ok {
		transactionID = id
	}

	if !strings.HasPrefix(path, "/") {
		path = "/" + path
	}
	if bodyBytes == nil {
		bodyBytes = []byte{}
	}

	baseURL := strings.TrimSuffix(s.config.BaseURL, "/")
	reqURL := baseURL + path

	// dev 排查走单一文件，避免 request/response/info 重复打点
	if !s.config.Debug && s.logger != nil {
		s.logger.LogRequest(requestID, transactionID, path, reqURL)
	}

	// nonce 与本地 request_id 保持一致，后续仅凭 request_id 即可对接上游排查
	signHeaders, err := SignHeaders(s.config.ClientID, s.config.ClientSecret, method, path, bodyBytes, requestID)
	if err != nil {
		err = errors.Join(ErrSystem, err)
		s.logError(requestID, transactionID, path, err, map[string]interface{}{"request_params": logParams})
		return nil, err
	}

	var bodyReader io.Reader
	if method != http.MethodGet && method != http.MethodHead {
		bodyReader = bytes.NewReader(bodyBytes)
	}

	req, err := http.NewRequestWithContext(ctx, method, reqURL, bodyReader)
	if err != nil {
		err = errors.Join(ErrSystem, err)
		s.logError(requestID, transactionID, path, err, map[string]interface{}{"request_params": logParams})
		return nil, err
	}
	curlHeaders := make(map[string]string, len(signHeaders)+1)
	if bodyReader != nil {
		req.Header.Set(headerContentType, contentTypeJSON)
		curlHeaders[headerContentType] = contentTypeJSON
	}
	for k, v := range signHeaders {
		req.Header.Set(k, v)
		curlHeaders[k] = v
	}

	var curlCmd string
	if s.config.Debug {
		bodyForCurl := ""
		if method != http.MethodGet && method != http.MethodHead {
			bodyForCurl = string(bodyBytes)
		}
		curlCmd = generateCurlCommand(method, reqURL, curlHeaders, bodyForCurl)
	}

	client := &http.Client{Timeout: s.config.Timeout}
	resp, err := client.Do(req)
	if err != nil {
		err = wrapHTTPError(err)
		s.logDebugExchange(requestID, transactionID, path, curlCmd, 0, time.Since(startTime), nil, err.Error())
		s.logError(requestID, transactionID, path, err, map[string]interface{}{"request_params": logParams})
		return nil, err
	}
	defer resp.Body.Close()

	duration := time.Since(startTime)
	raw, err := io.ReadAll(resp.Body)
	if err != nil {
		err = errors.Join(ErrSystem, err)
		s.logDebugExchange(requestID, transactionID, path, curlCmd, resp.StatusCode, duration, nil, err.Error())
		s.logError(requestID, transactionID, path, err, map[string]interface{}{"request_params": logParams})
		return nil, err
	}

	s.logDebugExchange(requestID, transactionID, path, curlCmd, resp.StatusCode, duration, raw, "")

	if resp.StatusCode != http.StatusOK {
		mapped := mapHTTPStatusError(resp.StatusCode, raw)
		s.logError(requestID, transactionID, path, mapped, map[string]interface{}{
			"request_params": logParams,
			"response_body":  truncateForLog(string(raw), maxLogResponseBodyLen),
			"http_status":    resp.StatusCode,
		})
		return nil, mapped
	}

	if !s.config.Debug && s.logger != nil {
		s.logger.LogResponse(requestID, transactionID, path, resp.StatusCode, duration)
	}

	var outer APIResponse
	if err := json.Unmarshal(raw, &outer); err != nil {
		parseErr := errors.Join(ErrSystem, fmt.Errorf("响应解析失败: %w", err))
		s.logError(requestID, transactionID, path, parseErr, map[string]interface{}{
			"request_params": logParams,
			"response_body":  truncateForLog(string(raw), maxLogResponseBodyLen),
		})
		return nil, parseErr
	}

	if !outer.Success {
		msg := "上游返回 success=false"
		if outer.ErrMessage != nil && *outer.ErrMessage != "" {
			msg = *outer.ErrMessage
		} else if outer.ErrCode != nil && *outer.ErrCode != "" {
			msg = *outer.ErrCode
		}
		mapped := errors.Join(ErrDatasource, errors.New(msg))
		s.logError(requestID, transactionID, path, mapped, map[string]interface{}{
			"request_params": logParams,
			"response_body":  truncateForLog(string(raw), maxLogResponseBodyLen),
		})
		return nil, mapped
	}

	billable, chargeFen := resolveBilling(resp.Header, outer.Billing)
	data := outer.Data
	if len(data) == 0 || string(data) == "null" {
		data = []byte("[]")
	}

	return &CallResult{
		Data:      data,
		Billable:  billable,
		ChargeFen: chargeFen,
		RequestID: outer.RequestID,
		Sandbox:   outer.Sandbox,
	}, nil
}

func resolveBilling(header http.Header, billing *BillingInfo) (billable bool, chargeFen int) {
	// 优先响应头（文档 9.2）
	if v := strings.TrimSpace(header.Get(headerBillable)); v != "" {
		billable = strings.EqualFold(v, "true")
	} else if billing != nil {
		billable = billing.Billable
	}

	if v := strings.TrimSpace(header.Get(headerChargeFen)); v != "" {
		if n, err := strconv.Atoi(v); err == nil {
			chargeFen = n
		}
	} else if billing != nil {
		chargeFen = billing.ChargeFen
	}

	// 幂等重放：上游不重复扣费
	if strings.EqualFold(strings.TrimSpace(header.Get(headerIdempotentReplay)), "true") {
		billable = false
		chargeFen = 0
	}
	return billable, chargeFen
}

func mapHTTPStatusError(status int, raw []byte) error {
	msg := strings.TrimSpace(string(raw))
	if len(msg) > 200 {
		msg = msg[:200]
	}
	detail := fmt.Sprintf("HTTP %d", status)
	if msg != "" {
		detail = detail + ": " + msg
	}

	switch status {
	case HTTPBadRequest:
		return errors.Join(ErrSystem, errors.New(detail))
	case HTTPUnauthorized, HTTPPaymentRequired, HTTPForbidden,
		HTTPConflict, HTTPTooManyRequests, HTTPBadGateway:
		return errors.Join(ErrDatasource, errors.New(detail))
	default:
		if status >= 500 {
			return errors.Join(ErrDatasource, errors.New(detail))
		}
		return errors.Join(ErrDatasource, errors.New(detail))
	}
}

func wrapHTTPError(err error) error {
	if err == context.DeadlineExceeded {
		return errors.Join(ErrDatasource, err)
	}
	if netErr, ok := err.(interface{ Timeout() bool }); ok && netErr.Timeout() {
		return errors.Join(ErrDatasource, err)
	}
	es := err.Error()
	if strings.Contains(es, "deadline exceeded") || strings.Contains(es, "timeout") || strings.Contains(es, "canceled") {
		return errors.Join(ErrDatasource, err)
	}
	return errors.Join(ErrSystem, err)
}

func (s *YuyuechaService) logError(requestID, transactionID, apiCode string, err error, params interface{}) {
	if s.logger != nil {
		s.logger.LogError(requestID, transactionID, apiCode, err, params)
	}
}

func (s *YuyuechaService) logDebugExchange(requestID, transactionID, apiCode, curlCmd string, statusCode int, duration time.Duration, raw []byte, errMsg string) {
	if !s.config.Debug {
		return
	}
	writeDebugExchange(s.config.DebugLogDir, debugExchangeRecord{
		RequestID:     requestID,
		TransactionID: transactionID,
		API:           apiCode,
		Status:        statusCode,
		Duration:      duration,
		Curl:          curlCmd,
		ResponseBody:  raw,
		Error:         errMsg,
	})
}