package h264dec

import (
	"math"

	"bitbucket.org/ausocean/av/codec/h264/h264dec/bits"
	"github.com/pkg/errors"
)

// import "strings"

// Specification Page 46 7.3.2.2

type PPS struct {
	ID, SPSID                         int
	EntropyCodingMode                 int
	BottomFieldPicOrderInFramePresent bool
	NumSliceGroupsMinus1              int
	SliceGroupMapType                 int
	RunLengthMinus1                   []int
	TopLeft                           []int
	BottomRight                       []int
	SliceGroupChangeDirection         bool
	SliceGroupChangeRateMinus1        int
	PicSizeInMapUnitsMinus1           int
	SliceGroupId                      []int
	NumRefIdxL0DefaultActiveMinus1    int
	NumRefIdxL1DefaultActiveMinus1    int
	WeightedPred                      bool
	WeightedBipred                    int
	PicInitQpMinus26                  int
	PicInitQsMinus26                  int
	ChromaQpIndexOffset               int
	DeblockingFilterControlPresent    bool
	ConstrainedIntraPred              bool
	RedundantPicCntPresent            bool
	Transform8x8Mode                  int
	PicScalingMatrixPresent           bool
	PicScalingListPresent             []bool
	SecondChromaQpIndexOffset         int
}

func NewPPS(br *bits.BitReader, chromaFormat int) (*PPS, error) {
	pps := PPS{}
	var err error

	pps.ID, err = readUe(br)
	if err != nil {
		return nil, errors.Wrap(err, "could not parse ID")
	}

	pps.SPSID, err = readUe(br)
	if err != nil {
		return nil, errors.Wrap(err, "could not parse SPS ID")
	}

	b, err := br.ReadBits(1)
	if err != nil {
		return nil, errors.Wrap(err, "could not read EntropyCodingMode")
	}
	pps.EntropyCodingMode = int(b)

	b, err = br.ReadBits(1)
	if err != nil {
		return nil, errors.Wrap(err, "could not read BottomFieldPicOrderInFramePresent")
	}
	pps.BottomFieldPicOrderInFramePresent = b == 1

	pps.NumSliceGroupsMinus1, err = readUe(br)
	if err != nil {
		return nil, errors.Wrap(err, "could not parse NumSliceGroupsMinus1")
	}

	if pps.NumSliceGroupsMinus1 > 0 {
		pps.SliceGroupMapType, err = readUe(br)
		if err != nil {
			return nil, errors.Wrap(err, "could not parse SliceGroupMapType")
		}

		if pps.SliceGroupMapType == 0 {
			for iGroup := 0; iGroup <= pps.NumSliceGroupsMinus1; iGroup++ {
				b, err := readUe(br)
				if err != nil {
					return nil, errors.Wrap(err, "could not parse RunLengthMinus1")
				}
				pps.RunLengthMinus1 = append(pps.RunLengthMinus1, b)
			}
		} else if pps.SliceGroupMapType == 2 {
			for iGroup := 0; iGroup < pps.NumSliceGroupsMinus1; iGroup++ {
				pps.TopLeft[iGroup], err = readUe(br)
				if err != nil {
					return nil, errors.Wrap(err, "could not parse TopLeft[iGroup]")
				}
				if err != nil {
					return nil, errors.Wrap(err, "could not parse TopLeft[iGroup]")
				}

				pps.BottomRight[iGroup], err = readUe(br)
				if err != nil {
					return nil, errors.Wrap(err, "could not parse BottomRight[iGroup]")
				}
			}
		} else if pps.SliceGroupMapType > 2 && pps.SliceGroupMapType < 6 {
			b, err = br.ReadBits(1)
			if err != nil {
				return nil, errors.Wrap(err, "could not read SliceGroupChangeDirection")
			}
			pps.SliceGroupChangeDirection = b == 1

			pps.SliceGroupChangeRateMinus1, err = readUe(br)
			if err != nil {
				return nil, errors.Wrap(err, "could not parse SliceGroupChangeRateMinus1")
			}
		} else if pps.SliceGroupMapType == 6 {
			pps.PicSizeInMapUnitsMinus1, err = readUe(br)
			if err != nil {
				return nil, errors.Wrap(err, "could not parse PicSizeInMapUnitsMinus1")
			}

			for i := 0; i <= pps.PicSizeInMapUnitsMinus1; i++ {
				b, err = br.ReadBits(int(math.Ceil(math.Log2(float64(pps.NumSliceGroupsMinus1 + 1)))))
				if err != nil {
					return nil, errors.Wrap(err, "coult not read SliceGroupId")
				}
				pps.SliceGroupId[i] = int(b)
			}
		}

	}
	pps.NumRefIdxL0DefaultActiveMinus1, err = readUe(br)
	if err != nil {
		return nil, errors.New("could not parse NumRefIdxL0DefaultActiveMinus1")
	}

	pps.NumRefIdxL1DefaultActiveMinus1, err = readUe(br)
	if err != nil {
		return nil, errors.New("could not parse NumRefIdxL1DefaultActiveMinus1")
	}

	b, err = br.ReadBits(1)
	if err != nil {
		return nil, errors.Wrap(err, "could not read WeightedPred")
	}
	pps.WeightedPred = b == 1

	b, err = br.ReadBits(2)
	if err != nil {
		return nil, errors.Wrap(err, "could not read WeightedBipred")
	}
	pps.WeightedBipred = int(b)

	pps.PicInitQpMinus26, err = readSe(br)
	if err != nil {
		return nil, errors.New("could not parse PicInitQpMinus26")
	}

	pps.PicInitQsMinus26, err = readSe(br)
	if err != nil {
		return nil, errors.New("could not parse PicInitQsMinus26")
	}

	pps.ChromaQpIndexOffset, err = readSe(br)
	if err != nil {
		return nil, errors.New("could not parse ChromaQpIndexOffset")
	}

	err = readFlags(br, []flag{
		{&pps.DeblockingFilterControlPresent, "DeblockingFilterControlPresent"},
		{&pps.ConstrainedIntraPred, "ConstrainedIntraPred"},
		{&pps.RedundantPicCntPresent, "RedundantPicCntPresent"},
	})
	if err != nil {
		return nil, err
	}

	logger.Printf("debug: \tChecking for more PPS data")
	if moreRBSPData(br) {
		logger.Printf("debug: \tProcessing additional PPS data")

		b, err = br.ReadBits(1)
		if err != nil {
			return nil, errors.Wrap(err, "could not read Transform8x8Mode")
		}
		pps.Transform8x8Mode = int(b)

		b, err = br.ReadBits(1)
		if err != nil {
			return nil, errors.Wrap(err, "could not read PicScalingMatrixPresent")
		}
		pps.PicScalingMatrixPresent = b == 1

		if pps.PicScalingMatrixPresent {
			v := 6
			if chromaFormat != chroma444 {
				v = 2
			}
			for i := 0; i < 6+(v*pps.Transform8x8Mode); i++ {
				b, err = br.ReadBits(1)
				if err != nil {
					return nil, errors.Wrap(err, "could not read PicScalingListPresent")
				}
				pps.PicScalingListPresent[i] = b == 1
				if pps.PicScalingListPresent[i] {
					if i < 6 {
						scalingList(
							br,
							ScalingList4x4[i],
							16,
							DefaultScalingMatrix4x4[i])

					} else {
						scalingList(
							br,
							ScalingList8x8[i],
							64,
							DefaultScalingMatrix8x8[i-6])

					}
				}
			}
		}
		pps.SecondChromaQpIndexOffset, err = readSe(br)
		if err != nil {
			return nil, errors.New("could not parse SecondChromaQpIndexOffset")
		}
	}
	moreRBSPData(br)
	return &pps, nil
}