//
//  dolmetschctl
//
//
//  Copyright (C) 2019 Christian Pointner <equinox@spreadspace.org>
//
//  This file is part of dolmetschctl.
//
//  dolmetschctl is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  any later version.
//
//  dolmetschctl 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 General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with dolmetschctl. If not, see <http://www.gnu.org/licenses/>.
//

package controller

import (
	"errors"
	"fmt"
	"strings"

	"github.com/scgolang/midi"
)

const (
	NOTE_OFFSET_BUTTON = byte(0x00)
	NUM_BUTTONS        = 4

	CC_LED          = byte(0xB0)
	NOTE_OFFSET_LED = byte(0x00)
	NUM_LEDS        = 4
	LED_OFF         = byte(0x00)
	LED_ON          = byte(0x01)
	LED_TOGGLE      = byte(0x02)
	LED_BLINK_MIN   = byte(0x03)
	LED_BLINK_MAX   = byte(0x7f)
)

type Controller struct {
	Dev *midi.Device
}

func openDevice(devices []*midi.Device, prefix string) (d *midi.Device, err error) {
	for _, device := range devices {
		if strings.HasPrefix(device.Name, prefix) {
			d = device
		}
	}
	if d == nil {
		return nil, errors.New("could not find device with prefix: " + prefix)
	}
	return d, d.Open()
}

func NewController(c Config) (*Controller, error) {
	devices, err := midi.Devices()
	if err != nil {
		return nil, err
	}

	ctrl := &Controller{}
	if ctrl.Dev, err = openDevice(devices, c.Dev); err != nil {
		return nil, err
	}
	ctrl.Dev.QueueSize = 100

	return ctrl, nil
}

func (c *Controller) Init() error {
	return nil
}

func (c *Controller) Shutdown() error {
	if c.Dev != nil {
		c.Dev.Close()
	}
	// TODO: also close all subscribed channels
	//       terminate go-routine started by Init()
	return nil
}

func (c *Controller) setLed(num byte, value byte) error {
	if num >= NUM_LEDS {
		return fmt.Errorf("this controller has only %d leds.", NUM_LEDS)
	}

	n, err := c.Dev.Write([]byte{CC_LED, NOTE_OFFSET_LED + num, value})
	if err != nil {
		// reopen device?
		return err
	}
	if n != 3 {
		return errors.New("sending LED command failed.")
	}
	return nil
}

func (c *Controller) LedOff(num byte) error {
	return c.setLed(num, LED_OFF)
}

func (c *Controller) LedOn(num byte) error {
	return c.setLed(num, LED_ON)
}

func (c *Controller) LedToggle(num byte) error {
	return c.setLed(num, LED_TOGGLE)
}

func (c *Controller) LedBlink(num, wait byte) error {
	if (wait + LED_BLINK_MIN) > LED_BLINK_MAX {
		return fmt.Errorf("blink wait must be between 0 and %d.", LED_BLINK_MAX-LED_BLINK_MIN)
	}
	return c.setLed(num, wait+LED_BLINK_MIN)
}