package mpeg

// https://wiki.multimedia.cx/index.php/MPEG-4_Audio

import (
	"github.com/wader/fq/format"
	"github.com/wader/fq/format/registry"
	"github.com/wader/fq/pkg/decode"
	"github.com/wader/fq/pkg/scalar"
)

func init() {
	registry.MustRegister(decode.Format{
		Name:        format.MPEG_ASC,
		Description: "MPEG-4 Audio Specific Config",
		DecodeFn:    ascDecoder,
	})
}

var frequencyIndexHz = map[uint64]int{
	0x0: 96000,
	0x1: 88200,
	0x2: 64000,
	0x3: 48000,
	0x4: 44100,
	0x5: 32000,
	0x6: 24000,
	0x7: 22050,
	0x8: 16000,
	0x9: 12000,
	0xa: 11025,
	0xb: 8000,
	0xc: 7350,
	0xd: -1,
	0xe: -1,
	0xf: -1,
}

var channelConfigurationNames = scalar.UToScalar{
	0: {Description: "defined in AOT Specifc Config"},
	1: {Description: "front-center"},
	2: {Description: "front-left, front-right"},
	3: {Description: "front-center, front-left, front-right"},
	4: {Description: "front-center, front-left, front-right, back-center"},
	5: {Description: "front-center, front-left, front-right, back-left, back-right"},
	6: {Description: "front-center, front-left, front-right, back-left, back-right, LFE-channel"},
	7: {Description: "front-center, front-left, front-right, side-left, side-right, back-left, back-right, LFE-channel"},
}

func ascDecoder(d *decode.D, in interface{}) interface{} {
	objectType := d.FieldUFn("object_type", func(d *decode.D) uint64 {
		n := d.U5()
		if n == 31 {
			n = 32 + d.U6()
		}
		return n
	}, format.MPEGAudioObjectTypeNames)
	d.FieldUScalarFn("sampling_frequency", func(d *decode.D) scalar.S {
		v := d.U4()
		if v == 15 {
			return scalar.S{Actual: d.U24()}
		}
		if f, ok := frequencyIndexHz[v]; ok {
			return scalar.S{Actual: v, Sym: f}
		}
		return scalar.S{Description: "invalid"}
	})
	d.FieldU4("channel_configuration", channelConfigurationNames)
	// TODO: GASpecificConfig etc
	d.FieldRawLen("var_aot_or_byte_align", d.BitsLeft())

	return format.MPEGASCOut{ObjectType: int(objectType)}
}