package filesystem

import (
	"fmt"
	"runtime"
)

// ErrorCode 错误码类型
type ErrorCode string

const (
	// 通用错误
	ErrCodeGeneral     ErrorCode = "GENERAL_ERROR"
	ErrCodeInvalid     ErrorCode = "INVALID_ARGUMENT"
	ErrCodeNotFound    ErrorCode = "NOT_FOUND"
	ErrCodePermission  ErrorCode = "PERMISSION_DENIED"
	ErrCodeIO          ErrorCode = "IO_ERROR"

	// 路径相关错误
	ErrCodePathTraversal  ErrorCode = "PATH_TRAVERSAL"
	ErrCodeInvalidPath    ErrorCode = "INVALID_PATH"
	ErrCodeSensitivePath  ErrorCode = "SENSITIVE_PATH"

	// 文件操作错误
	ErrCodeFileNotFound    ErrorCode = "FILE_NOT_FOUND"
	ErrCodeFileExists      ErrorCode = "FILE_EXISTS"
	ErrCodeDirectoryNotEmpty ErrorCode = "DIRECTORY_NOT_EMPTY"

	// 安全相关错误
	ErrCodeSecurityViolation ErrorCode = "SECURITY_VIOLATION"
	ErrCodeSizeLimit        ErrorCode = "SIZE_LIMIT_EXCEEDED"
	ErrCodeFileLocked      ErrorCode = "FILE_LOCKED"

	// ZIP相关错误
	ErrCodeZipInvalid    ErrorCode = "ZIP_INVALID"
	ErrCodeZipBomb       ErrorCode = "ZIP_BOMB"
	ErrCodeZipExtract    ErrorCode = "ZIP_EXTRACT_FAILED"
)

// FileError 文件系统专用错误类型
// 包含详细的错误上下文信息，便于调试和用户提示
type FileNotFoundError struct {
	Path string
	Err  error
}

func (e *FileNotFoundError) Error() string {
	return fmt.Sprintf("文件不存在: %s", e.Path)
}

func (e *FileNotFoundError) Unwrap() error {
	return e.Err
}

// PathValidationError 路径验证错误
type PathValidationError struct {
	Path        string
	Reason      string
	IsSensitive bool
}

func (e *PathValidationError) Error() string {
	return fmt.Sprintf("路径验证失败: %s - %s", e.Path, e.Reason)
}

// SecurityViolationError 安全违规错误
type SecurityViolationError struct {
	Path       string
	Violation  string
	Suggestion string
}

func (e *SecurityViolationError) Error() string {
	msg := fmt.Sprintf("安全违规: %s - %s", e.Path, e.Violation)
	if e.Suggestion != "" {
		msg += fmt.Sprintf("\n建议: %s", e.Suggestion)
	}
	return msg
}

// SizeLimitError 大小限制错误
type SizeLimitError struct {
	Path        string
	ActualSize  int64
	MaxSize     int64
	SizeType    string // "file" or "directory"
}

func (e *SizeLimitError) Error() string {
	return fmt.Sprintf("%s大小超限: %s (实际: %.2f GB, 限制: %.2f GB)",
		e.SizeType, e.Path,
		float64(e.ActualSize)/(1024*1024*1024),
		float64(e.MaxSize)/(1024*1024*1024),
	)
}

// FileLockedError 文件锁定错误
type FileLockedError struct {
	Path        string
	ProcessInfo string
}

func (e *FileLockedError) Error() string {
	msg := fmt.Sprintf("文件被占用: %s", e.Path)
	if e.ProcessInfo != "" {
		msg += fmt.Sprintf("\n占用程序: %s", e.ProcessInfo)
	}
	return msg
}

// WrapError 错误包装函数
// 添加上下文信息到错误中
func WrapError(operation string, path string, err error) error {
	return fmt.Errorf("%s 失败: %s - %w", operation, path, err)
}

// WrapErrorf 格式化错误包装
func WrapErrorf(format string, args ...interface{}) error {
	return fmt.Errorf(format, args...)
}

// GetStackTrace 获取堆栈跟踪（用于调试）
func GetStackTrace(skip int) string {
	buf := make([]byte, 4096)
	n := runtime.Stack(buf, false)
	if n > 0 {
		return string(buf[:n])
	}
	return ""
}