package main

type PrintValueCommand struct {}
func (cmd PrintValueCommand) exec(state *ProgramState) {
	for _, item := range state.space {
		state.out <- item
	}
}

type ToggleTerminalCommand struct {}
func (cmd ToggleTerminalCommand) exec(state *ProgramState) {
	toggled := map[TerminalValue]TerminalValue {
		ArrayBegin: MapBegin,
		ArrayEnd: MapEnd,
		MapBegin: ArrayBegin,
		MapEnd: ArrayEnd,
	}

	for i := range state.space {
		terminal, isTerminal := state.space[i].value.(TerminalValue)
		if !isTerminal {
			continue
		}
		state.space[i].value = toggled[terminal]
	}
}

type FilteredCommand struct {
	filter Filter
	command Command
}
func (cmd FilteredCommand) exec(state *ProgramState) {
	for _, item := range state.space {
		if cmd.filter.exec(item) {
			cmd.command.exec(state)
			return
		}
	}
}

type SequenceCommand struct {
	commands []Command
}
func (cmd SequenceCommand) exec(state *ProgramState) {
	for _, command := range cmd.commands {
		command.exec(state)
	}
}

type AppendLiteralCommand struct {
	values []WalkValue
}
func (cmd AppendLiteralCommand) exec(state *ProgramState) {
	for _, value := range cmd.values {
		state.space = append(state.space, WalkItem {
			path: nil,
			value: value,
		})
	}
}

type PrependLiteralCommand struct {
	values []WalkValue
}
func (cmd PrependLiteralCommand) exec(state *ProgramState) {
	var newItems []WalkItem
	for _, value := range cmd.values {
		newItems = append(newItems, WalkItem {
			path: nil,
			value: value,
		})
	}
	state.space = append(newItems, state.space...)
}

type NextCommand struct {}
func (cmd NextCommand) exec(state *ProgramState) {
	nextItem := <- state.in
	state.space = []WalkItem{nextItem}
}

type AppendNextCommand struct {}
func (cmd AppendNextCommand) exec(state *ProgramState) {
	nextItem := <- state.in
	state.space = append(state.space, nextItem)
}

type PrintLiteralsCommand struct {
	items []WalkItem
}
func (cmd PrintLiteralsCommand) exec(state *ProgramState) {
	for _, item := range cmd.items {
		state.out <- item
	}
}

type DeleteAllCommand struct {}
func (cmd DeleteAllCommand) exec(state *ProgramState) {
	state.space = nil
}

type Command interface {
	exec(*ProgramState)
}