//
//  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
	meterSegmentsGreen  float64 = 30
	meterSegmentsOrange float64 = 5
	meterSegmentsRed    float64 = 1
	meterSegmentsTotal  float64 = meterSegmentsGreen + meterSegmentsOrange + meterSegmentsRed
)

var (
	meterBarCSS *gtk.CssProvider = nil
)

func getMeterBarCSS() (*gtk.CssProvider, error) {
	if meterBarCSS != nil {
		return meterBarCSS, nil
	}

	var err error
	if meterBarCSS, err = gtk.CssProviderNew(); err != nil {
		return nil, err
	}
	err = meterBarCSS.LoadFromData(`
.level-bar {
  -GtkLevelBar-min-block-width: 13;
  -GtkLevelBar-min-block-height: 8;
}
.level-bar.trough {
  border: 0;
  padding: 0;
  border-radius: 0;
  background-image: unset;
}
.level-bar.fill-block {
  border-color: #323232
}
.level-bar.fill-block.level-green {
  border-color: #006600;
  background-image: linear-gradient(to bottom, #36B736, #006600);
}
.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 {
		return nil, err
	}
	return meterBarCSS, nil
}

type vuMeterLevel struct {
	green  float64
	orange float64
	red    float64
}

func (lvl *vuMeterLevel) setLevel(valdb float64) {
	if valdb < -1*meterDBFloor {
		valdb = -1 * meterDBFloor
	}

	val := valdb + meterDBFloor
	if val < 0 {
		val = 0
	} else {
		val = (val / meterDBFloor) * meterSegmentsTotal
	}

	lvl.green = val
	lvl.orange = val - meterSegmentsGreen
	lvl.red = lvl.orange - meterSegmentsOrange
	if lvl.orange < 0 {
		lvl.orange = 0
	}
	if lvl.red < 0 {
		lvl.red = 0
	}
	return
}

type vuMeter struct {
	label  *gtk.Label
	green  *gtk.LevelBar
	orange *gtk.LevelBar
	red    *gtk.LevelBar
}

func createMeterBar(segments float64) (bar *gtk.LevelBar, err error) {
	if bar, err = gtk.LevelBarNewForInterval(0, segments); err != nil {
		return
	}
	bar.SetMode(gtk.LEVEL_BAR_MODE_DISCRETE)
	bar.RemoveOffsetValue(gtk.LEVEL_BAR_OFFSET_LOW)
	bar.RemoveOffsetValue(gtk.LEVEL_BAR_OFFSET_HIGH)
	bar.SetHExpand(false)
	bar.SetVExpand(false)

	var sc *gtk.StyleContext
	if sc, err = bar.GetStyleContext(); err != nil {
		return
	}

	var cp *gtk.CssProvider
	if cp, err = getMeterBarCSS(); err != nil {
		return
	}
	sc.AddProvider(cp, 600) // TOOD: hardcoded value
	return
}

func newVUMeter(ch string) (meter *vuMeter, err error) {
	meter = &vuMeter{}
	if meter.label, err = gtk.LabelNew(ch); err != nil {
		return
	}
	if err = setCssStyle(&meter.label.Widget, ".label { color: #a2a2a2; padding: 0px 2px 0px 0px; font-size: 4.5px; font-variant: small-caps; font-weight: bold; }"); err != nil {
		return nil, err
	}

	if meter.green, err = createMeterBar(meterSegmentsGreen); err != nil {
		return
	}
	if meter.orange, err = createMeterBar(meterSegmentsOrange); err != nil {
		return
	}
	if meter.red, err = createMeterBar(meterSegmentsRed); err != nil {
		return
	}

	meter.green.AddOffsetValue("green", 0)
	meter.orange.AddOffsetValue("orange", 0)
	meter.red.AddOffsetValue("red", 0)

	return
}

func (m *vuMeter) SetValue(lvl *vuMeterLevel) {
	m.green.SetValue(lvl.green)
	m.orange.SetValue(lvl.orange)
	m.red.SetValue(lvl.red)
}

func updateVUMeterLevels(left, right *vuMeter, data player.Meter) {
	ch := len(data)
	lval := &vuMeterLevel{0, 0, 0}
	rval := &vuMeterLevel{0, 0, 0}
	if ch >= 2 {
		lval.setLevel(data[0].Peak)
		rval.setLevel(data[1].Peak)
	} else if ch == 1 {
		lval.setLevel(data[0].Peak)
		rval = lval
	}
	left.SetValue(lval)
	right.SetValue(rval)
}

func addVUMeterGrid(frame *gtk.Frame, p *player.PlayerChan) (err error) {
	var grid *gtk.Grid
	if grid, err = gtk.GridNew(); err != nil {
		return
	}
	grid.SetRowSpacing(2)

	var left, right *vuMeter
	if left, err = newVUMeter("L"); err != nil {
		return
	}
	if right, err = newVUMeter("R"); err != nil {
		return
	}

	p.AddUpdateHandler(func(_ time.Duration, _ time.Duration, meter player.Meter, _ interface{}) bool {
		glib.IdleAdd(func() { updateVUMeterLevels(left, right, meter) })
		return true
	}, nil)

	grid.Attach(left.label, 1, 1, 1, 1)
	grid.Attach(left.green, 2, 1, 1, 1)
	grid.Attach(left.orange, 3, 1, 1, 1)
	grid.Attach(left.red, 4, 1, 1, 1)

	grid.Attach(right.label, 1, 2, 1, 1)
	grid.Attach(right.green, 2, 2, 1, 1)
	grid.Attach(right.orange, 3, 2, 1, 1)
	grid.Attach(right.red, 4, 2, 1, 1)

	grid.SetRowHomogeneous(true)

	frame.Add(grid)
	return
}

func getVUMeterWidget(p *player.PlayerChan) (gtk.IWidget, error) {
	frame, err := gtk.FrameNew("")
	if err != nil {
		return nil, err
	}

	if err = setCssStyle(&frame.Widget, ".frame { background-color: #2a2a2a; border: 1px solid; border-color: #a1a1a1; border-radius: 5px; padding: 11px; }"); err != nil {
		return nil, err
	}

	if err = addVUMeterGrid(frame, p); err != nil {
		return nil, err
	}

	return frame, nil
}