package stt

import "fmt"

// ReadNil reads a json object as nil and
// returns whether it's a nil or not
func (iter *Iterator) ReadNil() (ret bool) {
	c := iter.nextToken()
	if c == 'n' {
		iter.skipBytes('u', 'l', 'l') // null
		return true
	}
	iter.unreadByte()
	return false
}

// ReadBool reads t/true/f/false/1/0 as BoolValue
func (iter *Iterator) ReadBool() (ret bool) {
	c := iter.nextToken()
	if c == 't' {
		iter.skipBytes('r', 'u', 'e')
		return true
	}
	if c == 'f' {
		iter.skipBytes('a', 'l', 's', 'e')
		return false
	}
	if c == '0' {
		return false
	}
	if c == '1' {
		return true
	}
	iter.ReportError("ReadBool", "expect t/true/1 or f/false/0, but found "+string([]byte{c}))
	return
}

// Skip skips an object and positions to relatively the next object
func (iter *Iterator) Skip() {
	iter.skipString()
}

func (iter *Iterator) skipString() {
	if !iter.trySkipString() {
		iter.unreadByte()
		iter.ReadString()
	}
}

func (iter *Iterator) trySkipString() bool {
	for i := iter.head; i < iter.tail; i++ {
		c := iter.buf[i]
		if c == '/' {
			iter.head = i
			return true // valid
		}
	}
	return false
}

func (iter *Iterator) skipBytes(bytes ...byte) {
	for _, b := range bytes {
		if iter.readByte() != b {
			iter.ReportError("skipBytes", fmt.Sprintf("expect %s", string(bytes)))
			return
		}
	}
}