/*
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 (
	"fmt"
)

// getStringValue will return a quoted string and the amount
// of bytes read
//
// an error will be returned if the string is not properly formatted
func getStringValue(b []rune) (int, error) {
	if b[0] != '"' {
		return 0, NewParseError("strings must start with '\"'")
	}

	endQuote := false
	i := 1

	for ; i < len(b) && !endQuote; i++ {
		if escaped := isEscaped(b[:i], b[i]); b[i] == '"' && !escaped {
			endQuote = true
			break
		} else if escaped {
			/*c, err := getEscapedByte(b[i])
			if err != nil {
				return 0, err
			}

			b[i-1] = c
			b = append(b[:i], b[i+1:]...)
			i--*/

			continue
		}
	}

	if !endQuote {
		return 0, NewParseError("missing '\"' in string value")
	}

	return i + 1, nil
}

// getBoolValue will return a boolean and the amount
// of bytes read
//
// an error will be returned if the boolean is not of a correct
// value
func getBoolValue(b []rune) (int, error) {
	if len(b) < 4 {
		return 0, NewParseError("invalid boolean value")
	}

	n := 0
	for _, lv := range literalValues {
		if len(lv) > len(b) {
			continue
		}

		if isLitValue(lv, b) {
			n = len(lv)
		}
	}

	if n == 0 {
		return 0, NewParseError("invalid boolean value")
	}

	return n, nil
}

// getNumericalValue will return a numerical string, the amount
// of bytes read, and the base of the number
//
// an error will be returned if the number is not of a correct
// value
func getNumericalValue(b []rune) (int, int, error) {
	if !isDigit(b[0]) {
		return 0, 0, NewParseError("invalid digit value")
	}

	i := 0
	helper := numberHelper{}

loop:
	for negativeIndex := 0; i < len(b); i++ {
		negativeIndex++

		if !isDigit(b[i]) {
			switch b[i] {
			case '-':
				if helper.IsNegative() || negativeIndex != 1 {
					return 0, 0, NewParseError("parse error '-'")
				}

				n := getNegativeNumber(b[i:])
				i += (n - 1)
				helper.Determine(b[i])
				continue
			case '.':
				if err := helper.Determine(b[i]); err != nil {
					return 0, 0, err
				}
			case 'e', 'E':
				if err := helper.Determine(b[i]); err != nil {
					return 0, 0, err
				}

				negativeIndex = 0
			case 'b':
				if helper.numberFormat == hex {
					break
				}
				fallthrough
			case 'o', 'x':
				if i == 0 && b[i] != '0' {
					return 0, 0, NewParseError("incorrect base format, expected leading '0'")
				}

				if i != 1 {
					return 0, 0, NewParseError(fmt.Sprintf("incorrect base format found %s at %d index", string(b[i]), i))
				}

				if err := helper.Determine(b[i]); err != nil {
					return 0, 0, err
				}
			default:
				if isWhitespace(b[i]) {
					break loop
				}

				if isNewline(b[i:]) {
					break loop
				}

				if !(helper.numberFormat == hex && isHexByte(b[i])) {
					if i+2 < len(b) && !isNewline(b[i:i+2]) {
						return 0, 0, NewParseError("invalid numerical character")
					} else if !isNewline([]rune{b[i]}) {
						return 0, 0, NewParseError("invalid numerical character")
					}

					break loop
				}
			}
		}
	}

	return helper.Base(), i, nil
}

// isDigit will return whether or not something is an integer
func isDigit(b rune) bool {
	return b >= '0' && b <= '9'
}

func hasExponent(v []rune) bool {
	return contains(v, 'e') || contains(v, 'E')
}

func isBinaryByte(b rune) bool {
	switch b {
	case '0', '1':
		return true
	default:
		return false
	}
}

func isOctalByte(b rune) bool {
	switch b {
	case '0', '1', '2', '3', '4', '5', '6', '7':
		return true
	default:
		return false
	}
}

func isHexByte(b rune) bool {
	if isDigit(b) {
		return true
	}
	return (b >= 'A' && b <= 'F') ||
		(b >= 'a' && b <= 'f')
}

func getValue(b []rune) (int, error) {
	i := 0

	for i < len(b) {
		if isNewline(b[i:]) {
			break
		}

		if isOp(b[i:]) {
			break
		}

		valid, n, err := isValid(b[i:])
		if err != nil {
			return 0, err
		}

		if !valid {
			break
		}

		i += n
	}

	return i, nil
}

// getNegativeNumber will return a negative number from a
// byte slice. This will iterate through all characters until
// a non-digit has been found.
func getNegativeNumber(b []rune) int {
	if b[0] != '-' {
		return 0
	}

	i := 1
	for ; i < len(b); i++ {
		if !isDigit(b[i]) {
			return i
		}
	}

	return i
}

// isEscaped will return whether or not the character is an escaped
// character.
func isEscaped(value []rune, b rune) bool {
	if len(value) == 0 {
		return false
	}

	switch b {
	case '\'': // single quote
	case '"': // quote
	case 'n': // newline
	case 't': // tab
	case '\\': // backslash
	default:
		return false
	}

	return value[len(value)-1] == '\\'
}

func getEscapedByte(b rune) (rune, error) {
	switch b {
	case '\'': // single quote
		return '\'', nil
	case '"': // quote
		return '"', nil
	case 'n': // newline
		return '\n', nil
	case 't': // table
		return '\t', nil
	case '\\': // backslash
		return '\\', nil
	default:
		return b, NewParseError(fmt.Sprintf("invalid escaped character %c", b))
	}
}

func removeEscapedCharacters(b []rune) []rune {
	for i := 0; i < len(b); i++ {
		if isEscaped(b[:i], b[i]) {
			c, err := getEscapedByte(b[i])
			if err != nil {
				return b
			}

			b[i-1] = c
			b = append(b[:i], b[i+1:]...)
			i--
		}
	}

	return b
}