use std::fmt::{self, Display};

// Shared
pub const COMMA_CHAR: u8 = b',';

// Newline
pub const NEWLINE_LF_CHAR: u8 = b'\n';
pub const NEWLINE_CR_CHAR: u8 = b'\r';

// Whitespace
pub const WHITESPACE_TAB_CHAR: u8 = b'\t';
pub const WHITESPACE_SPACE_CHAR: u8 = b' ';

// Real
pub const REAL_ZERO_CHAR: u8 = b'0';
pub const REAL_NEG_CHAR: u8 = b'-';
pub const REAL_SIGEXP_SEPARATOR_CHAR: u8 = b'e';

// Text
pub const TEXT_CHAR: u8 = b'"';
pub const MULTI_TEXT_CHAR: u8 = b'`';

// Kind
pub const KIND_NS_SEPARATOR_CHAR: u8 = b'/';

// Tag
pub const TAG_START_CHAR: u8 = b'(';
pub const TAG_END_CHAR: u8 = b')';

// Dict
pub const DICT_START_CHAR: u8 = b'{';
pub const DICT_END_CHAR: u8 = b'}';
pub const DICT_KV_SEPARATOR_CHAR: u8 = b':';
pub const DICT_PAIR_SEPARATOR_CHAR: u8 = COMMA_CHAR;

// List
pub const LIST_START_CHAR: u8 = b'[';
pub const LIST_END_CHAR: u8 = b']';
pub const LIST_SEPARATOR_CHAR: u8 = COMMA_CHAR;

// Comment
pub const COMMENT_CHAR: u8 = b'#';

// Boolean
pub const BOOLEAN_TRUE_KEYWORD: &[u8] = b"true";
pub const BOOLEAN_FALSE_KEYWORD: &[u8] = b"false";

#[derive(Clone, Debug, PartialEq)]
pub enum Token {
	// Non-value types
	Newline,
	Whitespace,
	Comment,
	AlphaLower,
	AlphaUpper,
	// Kinds
	KindNsSep,
	// Real
	RealMinus,
	RealZero,
	RealNumeric,
	RealSigExpSep,
	// Text
	TextStart,
	TextEnd,
	MultiTextStart,
	MultiTextEnd,
	// Structures
	TagStart,
	TagEnd,
	DictStart,
	DictEnd,
	DictKvSep,
	DictPairSep,
	ListStart,
	ListEnd,
	ListSep
}


impl Token {
	pub fn description(&self) -> &'static str {
		match self {
			Token::Newline => "newline '<lf/<crlf>'",
			Token::Whitespace => "whitespace '<tab/space>'",
			Token::Comment => "comment '#'",
			Token::AlphaLower => "alpha-lower '<a-z>'",
			Token::AlphaUpper => "alpha-upper '<A-Z>'",
			Token::KindNsSep => "kind ns separator '/'",
			Token::RealMinus => "minus '-'",
			Token::RealZero => "zero '0'",
			Token::RealNumeric => "number '<0-9>'",
			Token::RealSigExpSep => "sig-exp separator 'e'",
			Token::TextStart => "text '\"'",
			Token::TextEnd => "text end '\"'",
			Token::MultiTextStart => "multi text '`'",
			Token::MultiTextEnd => "multi text end '`'",
			Token::TagStart => "tag '('",
			Token::TagEnd => "tag end ')'",
			Token::DictStart => "dict '{'",
			Token::DictEnd => "dict end '}'",
			Token::DictKvSep => "dict kv separator ':'",
			Token::DictPairSep => "dict pair separator ','",
			Token::ListStart => "list '['",
			Token::ListEnd => "list end ']'",
			Token::ListSep => "list separator ','",
		}
	}
}

impl Display for Token {
	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
		write!(fmt, "{}", self.description())
	}
}