package parser

import (
	"strings"

	"asciigoat.org/core/lexer"
)

const (
	RuneComment      = ';'  // RuneComment is the standard INI comment character
	RuneCommentExtra = '#'  // RuneCommentExtra is UNIX shell's comment character
	RuneSectionStart = '['  // RuneSectionStart indicates the start of a section declaration
	RuneSectionEnd   = ']'  // RuneSectionEnd indicates the end of a section declaration
	RuneFieldEqual   = '='  // RuneFieldEqual separates field keys from their values
	RuneQuotes       = '"'  // RuneQuotes indicates the start and end of a quoted value
	RuneEscape       = '\\' // RuneEscape indicates the next rune is escaped
)

var (
	// RunesComment is a string containing all runes acceptable to start comments
	RunesComment = string([]rune{
		RuneComment,
		RuneCommentExtra,
	})
	// RunesSpecial is a string containing all the runes with special meaning
	RunesSpecial = string([]rune{
		RuneComment,
		RuneCommentExtra,
		RuneSectionStart,
		RuneSectionEnd,
		RuneFieldEqual,
		RuneQuotes,
		RuneEscape,
	})
)

var (
	// IsNewLine tells if the rune indicates a line break or the start of one
	IsNewLine = lexer.NewIsIn("\r\n")
	// IsNotNewLine tells if the rune is not a line break nor the start of one
	IsNotNewLine = lexer.NewIsNot(IsNewLine)
	// IsSpace tells if the rune is considered whitespace by Unicode
	IsSpace = lexer.IsSpace
	// IsNotSpace tells if the rune is not considered whitespace by Unicode
	IsNotSpace = lexer.NewIsNot(IsSpace)
	// IsCommentStart ...
	IsCommentStart = lexer.NewIsIn(RunesComment)
)

// IsAny accepts any rune
func IsAny(_ rune) bool {
	return true
}

// IsSpaceNotNewLine indicates a rune is whitespace but not a new line
func IsSpaceNotNewLine(r rune) bool {
	return IsSpace(r) && !IsNewLine(r)
}

// IsSectionStart indicates the rune starts the section declaration
func IsSectionStart(r rune) bool { return r == RuneSectionStart }

// IsSectionEnd indicates the rune ends the section declaration
func IsSectionEnd(r rune) bool { return r == RuneSectionEnd }

// IsName indicates a rune is acceptable for section or field names
func IsName(r rune) bool {
	switch {
	case IsSpace(r):
		return false
	case strings.ContainsRune(RunesSpecial, r):
		return false
	default:
		return true
	}
}