package tokenize

import (
	"unicode/utf8"
)

// Output provides output-related functionality for the tokenize API.
type Output struct {
	api    *API
	tokens []Token // accepted tokens
	data   []byte  // accepted data
}

func (o Output) String() string {
	bytes := o.data[o.api.stackFrame.bytesStart:o.api.stackFrame.bytesEnd]
	return string(bytes)
}

func (o Output) Runes() []rune {
	bytes := o.data[o.api.stackFrame.bytesStart:o.api.stackFrame.bytesEnd]
	return []rune(string(bytes))
}

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

func (o Output) ClearData() {
	o.api.stackFrame.bytesEnd = o.api.stackFrame.bytesStart
}

func (o Output) SetBytes(bytes ...byte) {
	o.ClearData()
	o.AddBytes(bytes...)
}

func (o Output) AddBytes(bytes ...byte) {
	// Grow the runes capacity when needed.
	newBytesEnd := o.api.stackFrame.bytesEnd + len(bytes)
	if cap(o.data) < newBytesEnd {
		newBytes := make([]byte, newBytesEnd*2)
		copy(newBytes, o.data)
		o.data = newBytes
	}

	copy(o.data[o.api.stackFrame.bytesEnd:], bytes)
	o.api.stackFrame.bytesEnd = newBytesEnd
}

func (o Output) SetRunes(runes ...rune) {
	o.ClearData()
	o.AddRunes(runes...)
}

func (o Output) AddRunes(runes ...rune) {
	// Grow the runes capacity when needed.
	runesAsString := string(runes)
	newBytesEnd := o.api.stackFrame.bytesEnd + len(runesAsString)
	if cap(o.data) < newBytesEnd {
		newBytes := make([]byte, newBytesEnd*2)
		copy(newBytes, o.data)
		o.data = newBytes
	}

	copy(o.data[o.api.stackFrame.bytesEnd:], runesAsString)
	o.api.stackFrame.bytesEnd = newBytesEnd
}

func (o Output) AddString(s string) {
	o.AddBytes([]byte(s)...)
}

func (o Output) SetString(s string) {
	o.ClearData()
	o.SetBytes([]byte(s)...)
}

func (o Output) Tokens() []Token {
	return o.tokens[o.api.stackFrame.tokenStart:o.api.stackFrame.tokenEnd]
}

func (o Output) Token(offset int) Token {
	return o.tokens[o.api.stackFrame.tokenStart+offset]
}

func (o Output) TokenValue(offset int) interface{} {
	return o.tokens[o.api.stackFrame.tokenStart+offset].Value
}

func (o Output) ClearTokens() {
	o.api.stackFrame.tokenEnd = o.api.stackFrame.tokenStart
}

func (o Output) SetTokens(tokens ...Token) {
	o.ClearTokens()
	o.AddTokens(tokens...)
}

func (o Output) AddTokens(tokens ...Token) {
	// Grow the tokens capacity when needed.
	newTokenEnd := o.api.stackFrame.tokenEnd + len(tokens)
	if cap(o.tokens) < newTokenEnd {
		newTokens := make([]Token, newTokenEnd*2)
		copy(newTokens, o.tokens)
		o.tokens = newTokens
	}

	for offset, t := range tokens {
		o.tokens[o.api.stackFrame.tokenEnd+offset] = t
	}
	o.api.stackFrame.tokenEnd = newTokenEnd
}