package wikilink

import (
	"log"
	"strings"
)

func lexFragment(l *Lexer) stateFn {
	log.Println("entering lexFragment")
	for {
		if strings.HasPrefix(l.input[l.pos:], CloseLink) {
			return lexCloseLink
		}

		if l.peek() == '^' {
			l.next()
			l.emit(ItemFragment)
			l.acceptRun("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 -.,")

			return lexInsideLink
		}

		return lexInsideLink
	}
}

func lexAlias(l *Lexer) stateFn {
	// l.accept
	log.Println("entering lexAlias")
	if strings.HasPrefix(l.input[l.pos:], CloseLink) {
		return lexCloseLink
	}
	l.emit(ItemAlias)

	return lexInsideLink
}

func lexInsideLink(l *Lexer) stateFn {
	log.Println("entering lexInsideLink")

	for {
		if strings.HasPrefix(l.input[l.pos:], CloseLink) {
			return lexCloseLink
		}

		r := l.next()
		log.Printf("inspecting %q\n", string(r))

		switch {
		case r == EOF:
		case r == '\n':
			return l.errorf("unclosed link")
		case r == '#':
			l.emit(ItemText)

			return lexFragment
		case r == '|':
			l.emit(ItemText)

			return lexAlias
		}
	}
}

func lexOpenLink(l *Lexer) stateFn {
	log.Println("entering lexOpenLink")
	l.pos += len(OpenLink)
	l.emit(ItemOpenLink)

	return lexInsideLink
}

func lexCloseLink(l *Lexer) stateFn {
	log.Println("entering lexCloseLink")
	l.pos += len(CloseLink)
	l.emit(ItemCloseLink)

	return lexText
}

func lexText(l *Lexer) stateFn {
	log.Println("entering lexText")

	for {
		if strings.HasPrefix(l.input[l.pos:], OpenLink) {
			if l.pos > l.start {
				l.emit(ItemText)
			}

			return lexOpenLink
		}

		if l.next() == EOF {
			break
		}
		if l.pos > l.start {
			l.emit(ItemText)
		}
		l.emit(ItemEOF)
		return nil
	}
	return nil
}