package lexer

import "fmt"

// Position indicates a line and column pair on a file.
// Counting starts at 1.
type Position struct {
	Line   int
	Column int
}

// String generates a pretty "(Line, Column)"" representation of the Position
func (p Position) String() string {
	if p.Line == 0 {
		p.Reset()
	}

	return fmt.Sprintf("(%v, %v)", p.Line, p.Column)
}

// GoString generates a string representation of the Position for %#v usage
func (p Position) GoString() string {
	if p.Line == 0 {
		p.Reset()
	}

	return fmt.Sprintf("lexer.Position{%v, %v}", p.Line, p.Column)
}

// Reset places a position at (1,1)
func (p *Position) Reset() {
	p.Line, p.Column = 1, 1
}

// Step moves the column one place
func (p *Position) Step() {
	if p.Line == 0 {
		p.Reset()
	}

	p.Column++
}

// Next returns a new Position one rune forward
// on the line
func (p Position) Next() Position {
	if p.Line == 0 {
		p.Reset()
	}

	return Position{
		Line:   p.Line,
		Column: p.Column + 1,
	}
}

// NextLine returns a new Position at the begining of the next
// line.
func (p Position) NextLine() Position {
	if p.Line == 0 {
		p.Reset()
	}

	return Position{
		Line:   p.Line + 1,
		Column: 1,
	}
}