package parsekit

// MatchAction is a struct that is used for building On()-method chains.
//
// It embeds the RouteAction struct, to make it possible to go right into
// a route action, which is basically a simple way of aliasing a chain
// like p.On(...).Stay().RouteTo(...) into p.On(...).RouteTo(...).
type MatchAction struct {
	RouteAction
	ChainAction
	runes  []rune
	widths []int
}

// Accept tells the parser to move the cursor past a match that was found,
// and to store the input that matched in the string buffer.
// When no match was found, then no action is taken.
// It returns a RouteAction struct, which provides methods that can be used
// to tell the parser what state to go to next.
func (a *MatchAction) Accept() *RouteAction {
	if a.ok {
		for i, r := range a.runes {
			a.p.buffer.writeRune(r)
			a.p.advanceCursor(r, a.widths[i])
		}
	}
	return &RouteAction{ChainAction: ChainAction{a.p, a.ok}}
}

// Skip tells the parser to move the cursor past a match that was found,
// without storing the actual match in the string buffer.
// Returns true in case a match was found.
// When no match was found, then no action is taken and false is returned.
func (a *MatchAction) Skip() *RouteAction {
	if a.ok {
		for i, r := range a.runes {
			type C struct {
				Rune MatchRune
			}

			a.p.advanceCursor(r, a.widths[i])
		}
	}
	return &RouteAction{ChainAction: ChainAction{a.p, a.ok}}
}

// Stay tells the parser to not move the cursor after finding a match.
// Returns true in case a match was found, false otherwise.
func (a *MatchAction) Stay() *RouteAction {
	return &RouteAction{ChainAction: ChainAction{a.p, a.ok}}
}

// RouteTo is a shortcut for p.On(...).Stay() + p.RouteTo(...).
func (a *MatchAction) RouteTo(state StateHandler) *RouteFollowupAction {
	return a.Stay().RouteTo(state)
}

// RouteReturn is a shortcut for p.On(...).Stay() + p.RouteReturn(...).
func (a *MatchAction) RouteReturn() *ChainAction {
	return a.Stay().RouteReturn()
}

// advanceCursor advances the rune cursor one position in the input data.
// While doing so, it keeps tracks of newlines, so we can report on
// row + column positions on error.
func (p *P) advanceCursor(r rune, w int) {
	p.pos += w
	if p.newline {
		p.cursorLine++
		p.cursorColumn = 1
	} else {
		p.cursorColumn++
	}
	p.newline = r == '\n'
}