/*
Copyright 2023 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package ini

// Copy from https://github.com/aws/aws-sdk-go
// May have been modified by Beijing Volcanoengine Technology Ltd.

import (
	"bytes"
	"io"
	"io/ioutil"

	"k8s.io/autoscaler/cluster-autoscaler/cloudprovider/volcengine/volcengine-go-sdk/volcengine/volcengineerr"
)

const (
	// ErrCodeUnableToReadFile is used when a file is failed to be
	// opened or read from.
	ErrCodeUnableToReadFile = "FailedRead"
)

// TokenType represents the various different tokens types
type TokenType int

func (t TokenType) String() string {
	switch t {
	case TokenNone:
		return "none"
	case TokenLit:
		return "literal"
	case TokenSep:
		return "sep"
	case TokenOp:
		return "op"
	case TokenWS:
		return "ws"
	case TokenNL:
		return "newline"
	case TokenComment:
		return "comment"
	case TokenComma:
		return "comma"
	default:
		return ""
	}
}

// TokenType enums
const (
	TokenNone = TokenType(iota)
	TokenLit
	TokenSep
	TokenComma
	TokenOp
	TokenWS
	TokenNL
	TokenComment
)

type iniLexer struct{}

// Tokenize will return a list of tokens during lexical analysis of the
// io.Reader.
func (l *iniLexer) Tokenize(r io.Reader) ([]Token, error) {
	b, err := ioutil.ReadAll(r)
	if err != nil {
		return nil, volcengineerr.New(ErrCodeUnableToReadFile, "unable to read file", err)
	}

	return l.tokenize(b)
}

func (l *iniLexer) tokenize(b []byte) ([]Token, error) {
	runes := bytes.Runes(b)
	var err error
	n := 0
	tokenAmount := countTokens(runes)
	tokens := make([]Token, tokenAmount)
	count := 0

	for len(runes) > 0 && count < tokenAmount {
		switch {
		case isWhitespace(runes[0]):
			tokens[count], n, err = newWSToken(runes)
		case isComma(runes[0]):
			tokens[count], n = newCommaToken(), 1
		case isComment(runes):
			tokens[count], n, err = newCommentToken(runes)
		case isNewline(runes):
			tokens[count], n, err = newNewlineToken(runes)
		case isSep(runes):
			tokens[count], n, err = newSepToken(runes)
		case isOp(runes):
			tokens[count], n, err = newOpToken(runes)
		default:
			tokens[count], n, err = newLitToken(runes)
		}

		if err != nil {
			return nil, err
		}

		count++

		runes = runes[n:]
	}

	return tokens[:count], nil
}

func countTokens(runes []rune) int {
	count, n := 0, 0
	var err error

	for len(runes) > 0 {
		switch {
		case isWhitespace(runes[0]):
			_, n, err = newWSToken(runes)
		case isComma(runes[0]):
			_, n = newCommaToken(), 1
		case isComment(runes):
			_, n, err = newCommentToken(runes)
		case isNewline(runes):
			_, n, err = newNewlineToken(runes)
		case isSep(runes):
			_, n, err = newSepToken(runes)
		case isOp(runes):
			_, n, err = newOpToken(runes)
		default:
			_, n, err = newLitToken(runes)
		}

		if err != nil {
			return 0
		}

		count++
		runes = runes[n:]
	}

	return count + 1
}

// Token indicates a metadata about a given value.
type Token struct {
	t         TokenType
	ValueType ValueType
	base      int
	raw       []rune
}

var emptyValue = Value{}

func newToken(t TokenType, raw []rune, v ValueType) Token {
	return Token{
		t:         t,
		raw:       raw,
		ValueType: v,
	}
}

// Raw return the raw runes that were consumed
func (tok Token) Raw() []rune {
	return tok.raw
}

// Type returns the token type
func (tok Token) Type() TokenType {
	return tok.t
}