package wav

import (
    "bytes"
    "encoding/binary"
    "fmt"

    "rtp-app/pkg/riff"
)

func DecodeSamplerChunk(d *Decoder, ch *riff.Chunk) error {
    if ch == nil {
        return fmt.Errorf("can't decode a nil chunk")
    }
    if d == nil {
        return fmt.Errorf("nil decoder")
    }
    if ch.ID == CIDSmpl {
        buf := make([]byte, ch.Size)
        var err error
        if _, err = ch.Read(buf); err != nil {
            return fmt.Errorf("failed to read the smpl chunk - %v", err)
        }
        if d.Metadata == nil {
            d.Metadata = &Metadata{}
        }
        d.Metadata.SamplerInfo = &SamplerInfo{}
        r := bytes.NewReader(buf)
        scratch := make([]byte, 4)
        if _, err = r.Read(scratch); err != nil {
            return fmt.Errorf("failed to read the smpl Manufacturer")
        }
        copy(d.Metadata.SamplerInfo.Manufacturer[:], scratch[:4])
        if _, err = r.Read(scratch); err != nil {
            return fmt.Errorf("failed to read the smpl Product")
        }
        copy(d.Metadata.SamplerInfo.Product[:], scratch[:4])

        if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.SamplePeriod); err != nil {
            return err
        }
        if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.MIDIUnityNote); err != nil {
            return err
        }
        if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.MIDIPitchFraction); err != nil {
            return err
        }
        if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.SMPTEFormat); err != nil {
            return err
        }
        if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.SMPTEOffset); err != nil {
            return err
        }
        if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.NumSampleLoops); err != nil {
            return err
        }
        var remaining uint32
        if err := binary.Read(r, binary.BigEndian, &remaining); err != nil {
            return err
        }
        if d.Metadata.SamplerInfo.NumSampleLoops > 0 {
            d.Metadata.SamplerInfo.Loops = []*SampleLoop{}
            for i := uint32(0); i < d.Metadata.SamplerInfo.NumSampleLoops; i++ {
                sl := &SampleLoop{}
                if _, err = r.Read(scratch); err != nil {
                    return fmt.Errorf("failed to read the sample loop cue point id")
                }
                copy(sl.CuePointID[:], scratch[:4])
                if err := binary.Read(r, binary.LittleEndian, &sl.Type); err != nil {
                    return err
                }
                if err := binary.Read(r, binary.LittleEndian, &sl.Start); err != nil {
                    return err
                }
                if err := binary.Read(r, binary.LittleEndian, &sl.End); err != nil {
                    return err
                }
                if err := binary.Read(r, binary.LittleEndian, &sl.Fraction); err != nil {
                    return err
                }
                if err := binary.Read(r, binary.LittleEndian, &sl.PlayCount); err != nil {
                    return err
                }
                d.Metadata.SamplerInfo.Loops = append(d.Metadata.SamplerInfo.Loops, sl)
            }
        }
    }
    ch.Drain()
    return nil
}