package wikilink

import (
	"strings"

	"go.uber.org/zap"
)

func isOpenLink(s string) bool {
	return strings.HasPrefix(s, OpenLink)
}

func isCloseLink(s string) bool {
	return strings.HasPrefix(s, CloseLink)
}

func isAlias(s string) bool {
	return strings.HasPrefix(s, Alias)
}

func isHeading(s string) bool {
	return strings.HasPrefix(s, Heading)
}

func isBlockRef(s string) bool {
	return strings.HasPrefix(s, BlockRef)
}

func lexIdent(l *Lexer) stateFn {
	for {
		r := l.next()
		l.L.Named("lexIdent").Debug("stepping through lexIdent",
			zap.String("r", string(r)),
		)
		s := l.input[l.GetPos():]
		if r == '\\' { // i think this will handle escape characters?
			break
		}
		switch {
		case isBlockRef(s):
			l.emit(ItemIdent)
			return lexBlockRef
		case isAlias(s):
			l.emit(ItemIdent)
			return lexAlias
		case isCloseLink(s):
			l.emit(ItemIdent)
			return lexCloseLink
		case isHeading(s):
			l.emit(ItemIdent)
			return lexHeading

		}
	}
	return l.errorf("malformed link")
}

func lexHeading(l *Lexer) stateFn {
	l.SetPos(l.GetPos() + len(Heading))
	l.emit(ItemHeading)

	return lexIdent
}

func lexBlockRef(l *Lexer) stateFn {
	l.SetPos(l.GetPos() + len(BlockRef))
	l.emit(ItemBlockRef)

	return lexIdent
}

func lexAlias(l *Lexer) stateFn {
	l.SetPos(l.GetPos() + len(Alias))
	l.emit(ItemAlias)

	return lexIdent
}

func lexText(l *Lexer) stateFn {
	for {
		if isOpenLink(l.input[l.GetPos():]) {
			return lexOpenLink
		}
		r := l.next()
		switch {
		case r == EOF || r == '\n':
			l.emit(ItemText)
			return nil
		}
	}
}

func lexOpenLink(l *Lexer) stateFn {
	l.SetPos(l.GetPos() + len(OpenLink))
	l.emit(ItemOpenLink)

	return lexIdent
}

func lexCloseLink(l *Lexer) stateFn {
	l.SetPos(l.GetPos() + len(CloseLink))
	l.emit(ItemCloseLink)

	return lexText
}