package logfmt

import (
	
	
	
	
	
	
	
	
)

// MarshalKeyvals returns the logfmt encoding of keyvals, a variadic sequence
// of alternating keys and values.
func ( ...interface{}) ([]byte, error) {
	 := &bytes.Buffer{}
	if  := NewEncoder().EncodeKeyvals(...);  != nil {
		return nil, 
	}
	return .Bytes(), nil
}

// An Encoder writes logfmt data to an output stream.
type Encoder struct {
	w       io.Writer
	scratch bytes.Buffer
	needSep bool
}

// NewEncoder returns a new encoder that writes to w.
func ( io.Writer) *Encoder {
	return &Encoder{
		w: ,
	}
}

var (
	space   = []byte(" ")
	equals  = []byte("=")
	newline = []byte("\n")
	null    = []byte("null")
)

// EncodeKeyval writes the logfmt encoding of key and value to the stream. A
// single space is written before the second and subsequent keys in a record.
// Nothing is written if a non-nil error is returned.
func ( *Encoder) (,  interface{}) error {
	.scratch.Reset()
	if .needSep {
		if ,  := .scratch.Write(space);  != nil {
			return 
		}
	}
	if  := writeKey(&.scratch, );  != nil {
		return 
	}
	if ,  := .scratch.Write(equals);  != nil {
		return 
	}
	if  := writeValue(&.scratch, );  != nil {
		return 
	}
	,  := .w.Write(.scratch.Bytes())
	.needSep = true
	return 
}

// EncodeKeyvals writes the logfmt encoding of keyvals to the stream. Keyvals
// is a variadic sequence of alternating keys and values. Keys of unsupported
// type are skipped along with their corresponding value. Values of
// unsupported type or that cause a MarshalerError are replaced by their error
// but do not cause EncodeKeyvals to return an error. If a non-nil error is
// returned some key/value pairs may not have be written.
func ( *Encoder) ( ...interface{}) error {
	if len() == 0 {
		return nil
	}
	if len()%2 == 1 {
		 = append(, nil)
	}
	for  := 0;  < len();  += 2 {
		,  := [], [+1]
		 := .EncodeKeyval(, )
		if  == ErrUnsupportedKeyType {
			continue
		}
		if ,  := .(*MarshalerError);  ||  == ErrUnsupportedValueType {
			 = 
			 = .EncodeKeyval(, )
		}
		if  != nil {
			return 
		}
	}
	return nil
}

// MarshalerError represents an error encountered while marshaling a value.
type MarshalerError struct {
	Type reflect.Type
	Err  error
}

func ( *MarshalerError) () string {
	return "error marshaling value of type " + .Type.String() + ": " + .Err.Error()
}

// ErrNilKey is returned by Marshal functions and Encoder methods if a key is
// a nil interface or pointer value.
var ErrNilKey = errors.New("nil key")

// ErrInvalidKey is returned by Marshal functions and Encoder methods if, after
// dropping invalid runes, a key is empty.
var ErrInvalidKey = errors.New("invalid key")

// ErrUnsupportedKeyType is returned by Encoder methods if a key has an
// unsupported type.
var ErrUnsupportedKeyType = errors.New("unsupported key type")

// ErrUnsupportedValueType is returned by Encoder methods if a value has an
// unsupported type.
var ErrUnsupportedValueType = errors.New("unsupported value type")

func writeKey( io.Writer,  interface{}) error {
	if  == nil {
		return ErrNilKey
	}

	switch k := .(type) {
	case string:
		return writeStringKey(, )
	case []byte:
		if  == nil {
			return ErrNilKey
		}
		return writeBytesKey(, )
	case encoding.TextMarshaler:
		,  := safeMarshal()
		if  != nil {
			return 
		}
		if  == nil {
			return ErrNilKey
		}
		return writeBytesKey(, )
	case fmt.Stringer:
		,  := safeString()
		if ! {
			return ErrNilKey
		}
		return writeStringKey(, )
	default:
		 := reflect.ValueOf()
		switch .Kind() {
		case reflect.Array, reflect.Chan, reflect.Func, reflect.Map, reflect.Slice, reflect.Struct:
			return ErrUnsupportedKeyType
		case reflect.Ptr:
			if .IsNil() {
				return ErrNilKey
			}
			return (, .Elem().Interface())
		}
		return writeStringKey(, fmt.Sprint())
	}
}

// keyRuneFilter returns r for all valid key runes, and -1 for all invalid key
// runes. When used as the mapping function for strings.Map and bytes.Map
// functions it causes them to remove invalid key runes from strings or byte
// slices respectively.
func keyRuneFilter( rune) rune {
	if  <= ' ' ||  == '=' ||  == '"' ||  == utf8.RuneError {
		return -1
	}
	return 
}

func writeStringKey( io.Writer,  string) error {
	 := strings.Map(keyRuneFilter, )
	if  == "" {
		return ErrInvalidKey
	}
	,  := io.WriteString(, )
	return 
}

func writeBytesKey( io.Writer,  []byte) error {
	 := bytes.Map(keyRuneFilter, )
	if len() == 0 {
		return ErrInvalidKey
	}
	,  := .Write()
	return 
}

func writeValue( io.Writer,  interface{}) error {
	switch v := .(type) {
	case nil:
		return writeBytesValue(, null)
	case string:
		return writeStringValue(, , true)
	case []byte:
		return writeBytesValue(, )
	case encoding.TextMarshaler:
		,  := safeMarshal()
		if  != nil {
			return 
		}
		if  == nil {
			 = null
		}
		return writeBytesValue(, )
	case error:
		,  := safeError()
		return writeStringValue(, , )
	case fmt.Stringer:
		,  := safeString()
		return writeStringValue(, , )
	default:
		 := reflect.ValueOf()
		switch .Kind() {
		case reflect.Array, reflect.Chan, reflect.Func, reflect.Map, reflect.Slice, reflect.Struct:
			return ErrUnsupportedValueType
		case reflect.Ptr:
			if .IsNil() {
				return writeBytesValue(, null)
			}
			return (, .Elem().Interface())
		}
		return writeStringValue(, fmt.Sprint(), true)
	}
}

func needsQuotedValueRune( rune) bool {
	return  <= ' ' ||  == '=' ||  == '"' ||  == utf8.RuneError
}

func writeStringValue( io.Writer,  string,  bool) error {
	var  error
	if  &&  == "null" {
		_,  = io.WriteString(, `"null"`)
	} else if strings.IndexFunc(, needsQuotedValueRune) != -1 {
		_,  = writeQuotedString(, )
	} else {
		_,  = io.WriteString(, )
	}
	return 
}

func writeBytesValue( io.Writer,  []byte) error {
	var  error
	if bytes.IndexFunc(, needsQuotedValueRune) != -1 {
		_,  = writeQuotedBytes(, )
	} else {
		_,  = .Write()
	}
	return 
}

// EndRecord writes a newline character to the stream and resets the encoder
// to the beginning of a new record.
func ( *Encoder) () error {
	,  := .w.Write(newline)
	if  == nil {
		.needSep = false
	}
	return 
}

// Reset resets the encoder to the beginning of a new record.
func ( *Encoder) () {
	.needSep = false
}

func safeError( error) ( string,  bool) {
	defer func() {
		if  := recover();  != nil {
			if  := reflect.ValueOf(); .Kind() == reflect.Ptr && .IsNil() {
				,  = "null", false
			} else {
				,  = fmt.Sprintf("PANIC:%v", ), false
			}
		}
	}()
	,  = .Error(), true
	return
}

func safeString( fmt.Stringer) ( string,  bool) {
	defer func() {
		if  := recover();  != nil {
			if  := reflect.ValueOf(); .Kind() == reflect.Ptr && .IsNil() {
				,  = "null", false
			} else {
				,  = fmt.Sprintf("PANIC:%v", ), true
			}
		}
	}()
	,  = .String(), true
	return
}

func safeMarshal( encoding.TextMarshaler) ( []byte,  error) {
	defer func() {
		if  := recover();  != nil {
			if  := reflect.ValueOf(); .Kind() == reflect.Ptr && .IsNil() {
				,  = nil, nil
			} else {
				,  = nil, fmt.Errorf("panic when marshalling: %s", )
			}
		}
	}()
	,  = .MarshalText()
	if  != nil {
		return nil, &MarshalerError{
			Type: reflect.TypeOf(),
			Err:  ,
		}
	}
	return
}