commands.go

// Sshwifty - A Web SSH client
//
// Copyright (C) 2019-2022 Ni Rui <ranqus@gmail.com>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package command

import (
	"errors"
	"fmt"

	"github.com/nirui/sshwifty/application/configuration"
	"github.com/nirui/sshwifty/application/log"
)

// Consts
const (
	MaxCommandID = 0x0f
)

// Errors
var (
	ErrCommandRunUndefinedCommand = errors.New(
		"undefined Command")
)

// Command represents a command handler machine builder
type Command func(
	l log.Logger,
	w StreamResponder,
	cfg Configuration,
) FSMMachine

// Builder builds a command
type Builder struct {
	name         string
	command      Command
	configurator configuration.PresetReloader
}

// Register builds a Builder for registration
func Register(name string, c Command, p configuration.PresetReloader) Builder {
	return Builder{
		name:         name,
		command:      c,
		configurator: p,
	}
}

// Commands contains data of all commands
type Commands [MaxCommandID + 1]Builder

// Register registers a new command
func (c *Commands) Register(
	id byte,
	name string,
	cb Command,
	ps configuration.PresetReloader,
) {
	if id > MaxCommandID {
		panic("Command ID must be not greater than MaxCommandID")
	}

	if (*c)[id].command != nil {
		panic(fmt.Sprintf("Command %d already been registered", id))
	}

	(*c)[id] = Register(name, cb, ps)
}

// Run creates command executer
func (c Commands) Run(
	id byte,
	l log.Logger,
	w StreamResponder,
	cfg Configuration,
) (FSM, error) {
	if id > MaxCommandID {
		return FSM{}, ErrCommandRunUndefinedCommand
	}

	cc := c[id]

	if cc.command == nil {
		return FSM{}, ErrCommandRunUndefinedCommand
	}

	return newFSM(cc.command(l, w, cfg)), nil
}

// Reconfigure lets commands reset configuration
func (c Commands) Reconfigure(
	p []configuration.Preset,
) ([]configuration.Preset, error) {
	newP := make([]configuration.Preset, 0, len(p))

	for i := range c {
		for pp := range p {
			if c[i].name != p[pp].Type {
				continue
			}

			newPP, pErr := c[i].configurator(p[pp])

			if pErr == nil {
				newP = append(newP, newPP)

				continue
			}

			return nil, pErr
		}
	}

	return newP, nil
}