//
//  rhlibrary
//
//  The Radio Helsinki Rivendell Library
//
//
//  Copyright (C) 2016 Christian Pointner <equinox@helsinki.at>
//
//  This file is part of rhlibrary.
//
//  rhlibrary 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.
//
//  rhlibrary 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 rhlibrary. If not, see <http://www.gnu.org/licenses/>.
//

package main

import (
	"time"

	"code.helsinki.at/rhrd-go/player"
	"github.com/gotk3/gotk3/glib"
	"github.com/gotk3/gotk3/gtk"
)

const (
	meterDBFloor  float64 = 72 // -72 db is the lowest VU value
	meterSegments float64 = 30 // meter has 30 elements

	meterOffsetGreen  float64 = meterSegments - 4
	meterOffsetOrange float64 = meterSegments - 2
	meterOffsetRed    float64 = meterSegments - 1
)

var (
	levelBarCss *gtk.CssProvider
)

func init() {
	var err error
	if levelBarCss, err = gtk.CssProviderNew(); err != nil {
		panic(err.Error())
	}
	err = levelBarCss.LoadFromData(`
.level-bar {
  -GtkLevelBar-min-block-width: 13;
  -GtkLevelBar-min-block-height: 8;
}
.level-bar.fill-block.level-green {
  border-color: #00AE00;
  background-image: linear-gradient(to bottom, #36FF36, #00AE00);
}
.level-bar.fill-block.level-orange {
  border-color: #AE6600;
  background-image: linear-gradient(to bottom, #FFAC36, #AE6600);
}
.level-bar.fill-block.level-red {
  border-color: #AE0000;
  background-image: linear-gradient(to bottom, #FF3636, #AE0000);
}`)
	if err != nil {
		panic(err.Error())
	}
}

func addPlayButton(grid *gtk.Grid, p *player.PlayerChan) (err error) {
	var btn *gtk.Button
	if btn, err = gtk.ButtonNewFromIconName("media-playback-start", gtk.ICON_SIZE_DIALOG); err != nil {
		return
	}
	btn.Connect("clicked", func(_ *gtk.Button) {
		if err := p.Play(); err != nil {
			rhdl.Println(err) // TODO: feedback at GUI?
		}
	})
	grid.Add(btn)
	return
}

func addPauseButton(grid *gtk.Grid, p *player.PlayerChan) (err error) {
	var btn *gtk.Button
	if btn, err = gtk.ButtonNewFromIconName("media-playback-pause", gtk.ICON_SIZE_DIALOG); err != nil {
		return
	}
	btn.Connect("clicked", func(_ *gtk.Button) {
		if err := p.Pause(); err != nil {
			rhdl.Println(err) // TODO: feedback at GUI?
		}
	})
	grid.Add(btn)
	return
}

func addStopButton(grid *gtk.Grid, p *player.PlayerChan) (err error) {
	var btn *gtk.Button
	if btn, err = gtk.ButtonNewFromIconName("media-playback-stop", gtk.ICON_SIZE_DIALOG); err != nil {
		return
	}
	btn.Connect("clicked", func(_ *gtk.Button) {
		if err := p.Stop(); err != nil {
			rhdl.Println(err) // TODO: feedback at GUI?
		}
	})
	grid.Add(btn)
	return
}

func calcMeterLevel(valdb float64) (val float64) {
	val = valdb + meterDBFloor
	if val < 0 {
		val = 0
	} else {
		val = (val / meterDBFloor) * meterSegments
	}
	return
}

func createMeterBar() (bar *gtk.LevelBar, err error) {
	if bar, err = gtk.LevelBarNewForInterval(0, meterSegments); err != nil {
		return
	}
	bar.SetMode(gtk.LEVEL_BAR_MODE_DISCRETE)
	bar.RemoveOffsetValue(gtk.LEVEL_BAR_OFFSET_LOW)
	bar.RemoveOffsetValue(gtk.LEVEL_BAR_OFFSET_HIGH)

	var sc *gtk.StyleContext
	if sc, err = bar.GetStyleContext(); err != nil {
		return
	}
	sc.AddProvider(levelBarCss, 600) // TOOD: hardcoded value

	bar.AddOffsetValue("green", meterOffsetGreen)
	bar.AddOffsetValue("orange", meterOffsetOrange)
	bar.AddOffsetValue("red", meterOffsetRed)

	return
}

func addMeter(grid *gtk.Grid, p *player.PlayerChan) (err error) {
	var mgrid *gtk.Grid
	if mgrid, err = gtk.GridNew(); err != nil {
		return
	}
	mgrid.SetOrientation(gtk.ORIENTATION_VERTICAL)
	mgrid.SetColumnSpacing(3)

	var left, right *gtk.LevelBar
	if left, err = createMeterBar(); err != nil {
		return
	}
	if right, err = createMeterBar(); err != nil {
		return
	}

	p.AddUpdateHandler(func(length time.Duration, pos time.Duration, meter player.Meter, userdata interface{}) bool {
		glib.IdleAdd(func() {
			ch := len(meter)
			lval := float64(0)
			rval := float64(0)
			if ch >= 2 {
				lval = calcMeterLevel(meter[0].Peak)
				rval = calcMeterLevel(meter[1].Peak)
			} else if ch == 1 {
				lval = calcMeterLevel(meter[0].Peak)
				rval = lval
			}
			left.SetValue(lval)
			right.SetValue(rval)
		})
		return true
	}, nil)

	mgrid.Add(left)
	mgrid.Add(right)

	grid.Add(mgrid)
	return
}

func getPlayerWidget(p *player.PlayerChan) (gtk.IWidget, error) {
	var err error
	var grid *gtk.Grid
	if grid, err = gtk.GridNew(); err != nil {
		return nil, err
	}
	grid.SetOrientation(gtk.ORIENTATION_HORIZONTAL)
	grid.SetColumnSpacing(3)

	if err = addPlayButton(grid, p); err != nil {
		return nil, err
	}
	if err = addPauseButton(grid, p); err != nil {
		return nil, err
	}
	if err = addStopButton(grid, p); err != nil {
		return nil, err
	}
	if err = addMeter(grid, p); err != nil {
		return nil, err
	}

	var frame *gtk.Frame
	if frame, err = gtk.FrameNew("player"); err != nil {
		return nil, err
	}
	frame.Add(grid)
	return frame, nil
}