package tokenize

import (
	"fmt"

	"git.makaay.nl/mauricem/go-parsekit/read"
)

// Input provides input-related functionality for the tokenize API,
// which is not specifically bound to a specific read mode (byte, rune).
type Input struct {
	api    *API
	reader *read.Buffer // the buffered input reader
}

// Cursor returns a string that describes the current read cursor position.
func (i Input) Cursor() string {
	column, line := 0, 0
	for _, f := range i.api.stackFrames[:i.api.stackLevel+1] {
		if f.line > 0 {
			column = f.column
			line += f.line
		} else {
			column += f.column
		}
	}
	if line == 0 && column == 0 {
		return fmt.Sprintf("start of file")
	}
	return fmt.Sprintf("line %d, column %d", line+1, column+1)
}

func (i Input) Reset() {
	f := i.api.stackFrame
	if f.offsetLocal > 0 {
		f.column = 0
		f.line = 0
		f.offset -= f.offsetLocal
		f.offsetLocal = 0
	}
}

// Flush flushes input data from the read buffer up to the current
// read cursor position of the tokenizer.
//
// Note: in most cases, you won't have to call this method yourself.
// Parsekit will call this method at points where it knows it is a
// safe thing to do.
func (i Input) Flush() bool {
	f := i.api.stackFrame
	if f.offset > 0 {
		i.reader.Flush(f.offset)
		f.offset = 0
		f.offsetLocal = 0
		return true
	}
	return false
}