package response

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"runtime"
	"strings"
	"time"

	"github.com/gogf/gf/v2/errors/gerror"
	"github.com/gogf/gf/v2/net/ghttp"

	"github.com/qianfree/team-api/internal/logic/common"
)

// ErrorLogRecord is a lightweight struct for async error log persistence.
type ErrorLogRecord struct {
	RequestId    string
	ErrorCode    int
	ErrorMessage string
	StackTrace   string
	HttpMethod   string
	RequestPath  string
	RequestBody  string
	Source       string
}

// errorLogWriter is the global async writer for sys_error_logs.
var errorLogWriter *common.UsageLogWriter

// InitErrorLogWriter initializes the global error log writer.
func InitErrorLogWriter() {
	errorLogWriter = common.NewUsageLogWriter(common.UsageLogWriterConfig{
		Table:         "sys_error_logs",
		QueueSize:     2048,
		BatchSize:     16,
		FlushInterval: 2 * time.Second,
		Workers:       2,
		Overflow:      common.OverflowDrop,
	})
	errorLogWriter.Start()
}

// CloseErrorLogWriter flushes and closes the global error log writer.
func CloseErrorLogWriter() {
	if errorLogWriter != nil {
		errorLogWriter.Close()
	}
}

// captureStackTrace captures the current goroutine's stack trace.
func captureStackTrace(skip int) string {
	pcs := make([]uintptr, 32)
	n := runtime.Callers(skip+2, pcs)
	if n == 0 {
		return ""
	}
	frames := runtime.CallersFrames(pcs[:n])
	var b strings.Builder
	for {
		frame, more := frames.Next()
		fmt.Fprintf(&b, "%s\n\t%s:%d\n", frame.Function, frame.File, frame.Line)
		if !more {
			break
		}
	}
	return b.String()
}

// truncateString truncates a string to maxLen bytes.
func truncateString(s string, maxLen int) string {
	if len(s) <= maxLen {
		return s
	}
	return s[:maxLen] + "..."
}

// sensitiveBodyKeys 命中这些子串（大小写不敏感）的 JSON 字段值会被脱敏，
// 防止明文密码/密钥/令牌/验证码等随请求体写入 sys_error_logs。
var sensitiveBodyKeys = []string{
	"password", "passwd", "pwd", "secret", "token",
	"api_key", "apikey", "access_key", "private_key",
	"credential", "authorization", "otp", "totp", "code",
}

// isSensitiveKey 判断字段名是否命中敏感词。
func isSensitiveKey(key string) bool {
	lower := strings.ToLower(key)
	for _, s := range sensitiveBodyKeys {
		if strings.Contains(lower, s) {
			return true
		}
	}
	return false
}

// redactValue 递归脱敏 map/slice 中命中敏感词的字段。
func redactValue(v interface{}) interface{} {
	switch val := v.(type) {
	case map[string]interface{}:
		for k, item := range val {
			if isSensitiveKey(k) {
				val[k] = "[REDACTED]"
			} else {
				val[k] = redactValue(item)
			}
		}
		return val
	case []interface{}:
		for i, item := range val {
			val[i] = redactValue(item)
		}
		return val
	default:
		return v
	}
}

// sanitizeRequestBody 对 JSON 请求体做敏感字段脱敏后返回。
// 非 JSON 或解析失败时无法可靠定位敏感字段，直接返回占位符而不落原文，
// 确保任何情况下都不会把明文密码/密钥写入错误日志表。
func sanitizeRequestBody(body string) string {
	if body == "" {
		return ""
	}
	var parsed interface{}
	if err := json.Unmarshal([]byte(body), &parsed); err != nil {
		return "[non-json body omitted]"
	}
	out, err := json.Marshal(redactValue(parsed))
	if err != nil {
		return "[redaction failed]"
	}
	return string(out)
}

// safeRequestBodyForLog 按 Content-Type 决定是否读取并记录请求体：
//   - multipart/二进制：跳过 r.GetBodyString()（避免把整段 base64 图片/二进制读入
//     内存并落库），直接返回占位符；
//   - 其它：脱敏 + 截断后返回。
//
// 调用方原本无条件 r.GetBodyString()，对大体积 multipart 上传会把整个文件读进内存，
// 即便后续 sanitize 会丢弃也无法省去这次拷贝。
func safeRequestBodyForLog(r *ghttp.Request) string {
	contentType := r.Header.Get("Content-Type")
	// multipart/form-data、image/*、audio/*、video/*、application/octet-stream 等均视为二进制
	if isBinaryContentType(contentType) {
		return "[binary body omitted]"
	}
	return truncateString(sanitizeRequestBody(r.GetBodyString()), 2000)
}

// isBinaryContentType 判断 Content-Type 是否为不应落库的二进制/大体积类型。
func isBinaryContentType(contentType string) bool {
	lower := strings.ToLower(contentType)
	if lower == "" {
		return false
	}
	// 取分号前的主类型，如 "multipart/form-data; boundary=..." → "multipart/form-data"
	if i := strings.IndexByte(lower, ';'); i >= 0 {
		lower = strings.TrimSpace(lower[:i])
	}
	switch {
	case strings.HasPrefix(lower, "multipart/"):
		return true
	case strings.HasPrefix(lower, "image/"):
		return true
	case strings.HasPrefix(lower, "audio/"):
		return true
	case strings.HasPrefix(lower, "video/"):
		return true
	case lower == "application/octet-stream":
		return true
	}
	return false
}

// writeErrorLog submits an error record to the async writer.
func writeErrorLog(r *ErrorLogRecord) {
	if errorLogWriter == nil {
		return
	}
	errorLogWriter.Submit(r)
}

// WriteErrorLogFromCtx writes an error log from non-HTTP context (cron/background).
func WriteErrorLogFromCtx(ctx context.Context, err error, source string) {
	if errorLogWriter == nil {
		return
	}
	code := 500
	var gerr *gerror.Error
	if errors.As(err, &gerr) {
		code = gerr.Code().Code()
		if code == 0 {
			code = 500
		}
	}
	errorLogWriter.Submit(&ErrorLogRecord{
		ErrorCode:    code,
		ErrorMessage: err.Error(),
		StackTrace:   captureStackTrace(2),
		Source:       source,
		RequestId:    getRequestIDFromCtx(ctx),
	})
}

// WritePanicLog writes a panic record to sys_error_logs (called from Recovery middleware).
func WritePanicLog(requestID, httpMethod, requestPath, errMsg, stack string) {
	if errorLogWriter == nil {
		return
	}
	errorLogWriter.Submit(&ErrorLogRecord{
		RequestId:    requestID,
		ErrorCode:    500,
		ErrorMessage: errMsg,
		StackTrace:   stack,
		HttpMethod:   httpMethod,
		RequestPath:  requestPath,
		Source:       "panic",
	})
}

// getRequestIDFromCtx extracts request ID from GoFrame context.
func getRequestIDFromCtx(ctx context.Context) string {
	if ctx != nil {
		if v := ctx.Value("RequestId"); v != nil {
			if s, ok := v.(string); ok {
				return s
			}
		}
	}
	return ""
}