package logger

import (
	"context"
	"strings"

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
)

// LogLevel 日志级别
type LogLevel string

const (
	DebugLevel LogLevel = "debug"
	InfoLevel  LogLevel = "info"
	WarnLevel  LogLevel = "warn"
	ErrorLevel LogLevel = "error"
)

// LogContext 日志上下文
type LogContext struct {
	RequestID     string
	UserID        string
	TraceID       string
	OperationName string
	Layer         string // repository/service/handler
	Component     string
}

// ContextualLogger 上下文感知的日志器
type ContextualLogger struct {
	logger *zap.Logger
	ctx    LogContext
}

// NewContextualLogger 创建上下文日志器
func NewContextualLogger(logger *zap.Logger) *ContextualLogger {
	return &ContextualLogger{
		logger: logger,
	}
}

// WithContext 添加上下文信息
func (l *ContextualLogger) WithContext(ctx context.Context) *ContextualLogger {
	logCtx := LogContext{}

	// 从context中提取常用字段
	if requestID := getStringFromContext(ctx, "request_id"); requestID != "" {
		logCtx.RequestID = requestID
	}
	if userID := getStringFromContext(ctx, "user_id"); userID != "" {
		logCtx.UserID = userID
	}
	if traceID := getStringFromContext(ctx, "trace_id"); traceID != "" {
		logCtx.TraceID = traceID
	}

	return &ContextualLogger{
		logger: l.logger,
		ctx:    logCtx,
	}
}

// WithLayer 设置层级信息
func (l *ContextualLogger) WithLayer(layer string) *ContextualLogger {
	newCtx := l.ctx
	newCtx.Layer = layer
	return &ContextualLogger{
		logger: l.logger,
		ctx:    newCtx,
	}
}

// WithComponent 设置组件信息
func (l *ContextualLogger) WithComponent(component string) *ContextualLogger {
	newCtx := l.ctx
	newCtx.Component = component
	return &ContextualLogger{
		logger: l.logger,
		ctx:    newCtx,
	}
}

// WithOperation 设置操作名称
func (l *ContextualLogger) WithOperation(operation string) *ContextualLogger {
	newCtx := l.ctx
	newCtx.OperationName = operation
	return &ContextualLogger{
		logger: l.logger,
		ctx:    newCtx,
	}
}

// 构建基础字段
func (l *ContextualLogger) buildBaseFields() []zapcore.Field {
	fields := []zapcore.Field{}

	if l.ctx.RequestID != "" {
		fields = append(fields, zap.String("request_id", l.ctx.RequestID))
	}
	if l.ctx.UserID != "" {
		fields = append(fields, zap.String("user_id", l.ctx.UserID))
	}
	if l.ctx.TraceID != "" {
		fields = append(fields, zap.String("trace_id", l.ctx.TraceID))
	}
	if l.ctx.Layer != "" {
		fields = append(fields, zap.String("layer", l.ctx.Layer))
	}
	if l.ctx.Component != "" {
		fields = append(fields, zap.String("component", l.ctx.Component))
	}
	if l.ctx.OperationName != "" {
		fields = append(fields, zap.String("operation", l.ctx.OperationName))
	}

	return fields
}

// LogTechnicalError 记录技术性错误（Repository层）
func (l *ContextualLogger) LogTechnicalError(msg string, err error, fields ...zapcore.Field) {
	allFields := l.buildBaseFields()
	allFields = append(allFields, zap.Error(err))
	allFields = append(allFields, zap.String("error_type", "technical"))
	allFields = append(allFields, fields...)

	l.logger.Error(msg, allFields...)
}

// LogBusinessWarn 记录业务警告（Service层）
func (l *ContextualLogger) LogBusinessWarn(msg string, fields ...zapcore.Field) {
	allFields := l.buildBaseFields()
	allFields = append(allFields, zap.String("log_type", "business"))
	allFields = append(allFields, fields...)

	l.logger.Warn(msg, allFields...)
}

// LogBusinessInfo 记录业务信息（Service层）
func (l *ContextualLogger) LogBusinessInfo(msg string, fields ...zapcore.Field) {
	allFields := l.buildBaseFields()
	allFields = append(allFields, zap.String("log_type", "business"))
	allFields = append(allFields, fields...)

	l.logger.Info(msg, allFields...)
}

// LogUserAction 记录用户行为（Handler层）
func (l *ContextualLogger) LogUserAction(msg string, fields ...zapcore.Field) {
	allFields := l.buildBaseFields()
	allFields = append(allFields, zap.String("log_type", "user_action"))
	allFields = append(allFields, fields...)

	l.logger.Info(msg, allFields...)
}

// LogRequestFailed 记录请求失败（Handler层）
func (l *ContextualLogger) LogRequestFailed(msg string, errorType string, fields ...zapcore.Field) {
	allFields := l.buildBaseFields()
	allFields = append(allFields, zap.String("log_type", "request_failed"))
	allFields = append(allFields, zap.String("error_category", errorType))
	allFields = append(allFields, fields...)

	l.logger.Info(msg, allFields...)
}

// getStringFromContext 从上下文获取字符串值
func getStringFromContext(ctx context.Context, key string) string {
	if value := ctx.Value(key); value != nil {
		if str, ok := value.(string); ok {
			return str
		}
	}
	return ""
}

// ErrorCategory 错误分类
type ErrorCategory string

const (
	DatabaseError    ErrorCategory = "database"
	NetworkError     ErrorCategory = "network"
	ValidationError  ErrorCategory = "validation"
	BusinessError    ErrorCategory = "business"
	AuthError        ErrorCategory = "auth"
	ExternalAPIError ErrorCategory = "external_api"
)

// CategorizeError 错误分类
func CategorizeError(err error) ErrorCategory {
	errMsg := strings.ToLower(err.Error())

	switch {
	case strings.Contains(errMsg, "database") ||
		strings.Contains(errMsg, "sql") ||
		strings.Contains(errMsg, "gorm"):
		return DatabaseError
	case strings.Contains(errMsg, "network") ||
		strings.Contains(errMsg, "connection") ||
		strings.Contains(errMsg, "timeout"):
		return NetworkError
	case strings.Contains(errMsg, "validation") ||
		strings.Contains(errMsg, "invalid") ||
		strings.Contains(errMsg, "format"):
		return ValidationError
	case strings.Contains(errMsg, "unauthorized") ||
		strings.Contains(errMsg, "forbidden") ||
		strings.Contains(errMsg, "token"):
		return AuthError
	default:
		return BusinessError
	}
}