package tokenize

import (
	"unicode/utf8"
)

// Output provides output-related functionality for the tokenize API.
type Output struct {
	api       *API
	suspended int // whether or not the output has been suspended (i.e. value > 0)
}

func (o *Output) Suspend() {
	o.suspended++
}

func (o *Output) Resume() {
	o.suspended--
}

func (o Output) Bytes() []byte {
	a := o.api
	return a.outputBytes[a.pointers.bytesStart:a.pointers.bytesEnd]
}

func (o Output) String() string {
	return string(o.Bytes())
}

func (o Output) Runes() []rune {
	return []rune(o.String())
}

func (o Output) Rune(offset int) rune {
	a := o.api
	r, _ := utf8.DecodeRune(a.outputBytes[a.pointers.bytesStart+offset:])
	return r
}

func (o Output) Flush() {
	a := o.api
	a.pointers.bytesStart = a.pointers.bytesEnd
	a.pointers.tokenStart = a.pointers.tokenEnd
}

func (o Output) ClearData() {
	if o.suspended > 0 {
		return
	}
	a := o.api
	a.pointers.bytesEnd = a.pointers.bytesStart
}

func (o Output) SetBytes(bytes ...byte) {
	if o.suspended > 0 {
		return
	}
	o.ClearData()
	o.AddBytes(bytes...)
}

func (o Output) AddByte(b byte) {
	if o.suspended > 0 {
		return
	}
	a := o.api
	curBytesEnd := a.pointers.bytesEnd
	a.growOutputData(curBytesEnd + 1)
	a.outputBytes[curBytesEnd] = b
	a.pointers.bytesEnd++
}

func (o Output) SetRunes(runes ...rune) {
	if o.suspended > 0 {
		return
	}
	o.ClearData()
	o.AddRunes(runes...)
}

func (o Output) AddBytes(bytes ...byte) {
	if o.suspended > 0 {
		return
	}
	a := o.api
	curBytesEnd := a.pointers.bytesEnd
	newBytesEnd := curBytesEnd + len(bytes)
	a.growOutputData(newBytesEnd)
	copy(a.outputBytes[curBytesEnd:], bytes)
	a.pointers.bytesEnd = newBytesEnd
}

func (o Output) AddRunes(runes ...rune) {
	if o.suspended > 0 {
		return
	}
	a := o.api
	runesAsString := string(runes)
	newBytesEnd := a.pointers.bytesEnd + len(runesAsString)
	a.growOutputData(newBytesEnd)
	copy(a.outputBytes[a.pointers.bytesEnd:], runesAsString)
	a.pointers.bytesEnd = newBytesEnd
}

func (o Output) AddString(s string) {
	if o.suspended > 0 {
		return
	}
	o.AddBytes([]byte(s)...)
}

func (o Output) SetString(s string) {
	if o.suspended > 0 {
		return
	}
	o.ClearData()
	o.AddBytes([]byte(s)...)
}

func (o Output) Tokens() []Token {
	a := o.api
	return a.outputTokens[a.pointers.tokenStart:a.pointers.tokenEnd]
}

func (o Output) Token(offset int) Token {
	a := o.api
	return a.outputTokens[a.pointers.tokenStart+offset]
}

func (o Output) TokenValue(offset int) interface{} {
	a := o.api
	return a.outputTokens[a.pointers.tokenStart+offset].Value
}

func (o Output) ClearTokens() {
	if o.suspended > 0 {
		return
	}
	a := o.api
	a.pointers.tokenEnd = a.pointers.tokenStart
}

func (o Output) SetTokens(tokens ...Token) {
	if o.suspended > 0 {
		return
	}
	o.ClearTokens()
	o.AddTokens(tokens...)
}

func (o Output) AddToken(token Token) {
	if o.suspended > 0 {
		return
	}
	a := o.api
	tokenEnd := a.pointers.tokenEnd
	a.growOutputTokens(tokenEnd + 1)
	a.outputTokens[tokenEnd] = token
	a.pointers.tokenEnd++
}

func (o Output) InsertTokenAtStart(token Token) {
	if o.suspended > 0 {
		return
	}
	a := o.api
	tokenEnd := a.pointers.tokenEnd
	tokenStart := a.pointers.tokenStart
	a.growOutputTokens(tokenEnd + 1)
	if tokenStart == tokenEnd {
		a.outputTokens[tokenEnd] = token
	} else {
		copy(a.outputTokens[tokenStart+1:], a.outputTokens[tokenStart:tokenEnd])
		a.outputTokens[tokenStart] = token
	}
	a.pointers.tokenEnd++
}

func (o Output) AddTokens(tokens ...Token) {
	if o.suspended > 0 {
		return
	}
	a := o.api
	a.growOutputTokens(a.pointers.tokenEnd + len(tokens))
	for _, t := range tokens {
		a.outputTokens[a.pointers.tokenEnd] = t
		a.pointers.tokenEnd++
	}
}

func (api *API) growOutputTokens(requiredTokens int) {
	if cap(api.outputTokens) < requiredTokens {
		newTokens := make([]Token, requiredTokens*2)
		copy(newTokens, api.outputTokens)
		api.outputTokens = newTokens
	}
}

func (api *API) growOutputData(requiredBytes int) {
	if cap(api.outputBytes) < requiredBytes {
		newBytes := make([]byte, requiredBytes*2)
		copy(newBytes, api.outputBytes)
		api.outputBytes = newBytes
	}
}