package meta

import (
	"bytes"
	"io"

	"github.com/pkg/errors"
	"github.com/vmihailenco/msgpack/v5"
	"github.com/vmihailenco/msgpack/v5/msgpcode"
)

type msgpackAssocReader struct {
	dec   *msgpack.Decoder
	stack []assocReadContainer
	curr  assocReadContainer
}

type assocReadContainer struct {
	started bool
	length  int
	assoc   bool
	values  map[string]msgpack.RawMessage
	reader  io.Reader
	readCnt int
}

func NewMsgpackAssocReader(r io.Reader) Reader {
	return &msgpackAssocReader{
		dec:   msgpack.NewDecoder(r),
		stack: make([]assocReadContainer, 0, 2),
		curr: assocReadContainer{
			reader: r,
		},
	}
}

func (rd *msgpackAssocReader) readField() (string, error) {
	field, err := rd.dec.DecodeString()
	if err != nil {
		return "", errors.WithStack(err)
	}
	return field, nil
}

func (rd *msgpackAssocReader) ReadInt8(v *int8, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeInt8(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeInt8(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeInt8(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadInt16(v *int16, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeInt16(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeInt16(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeInt16(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadInt32(v *int32, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeInt32(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeInt32(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeInt32(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadInt64(v *int64, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeInt64(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeInt64(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeInt64(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadUint8(v *uint8, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeUint8(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeUint8(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeUint8(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadUint16(v *uint16, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeUint16(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeUint16(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeUint16(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadUint32(v *uint32, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeUint32(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeUint32(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeUint32(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadUint64(v *uint64, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeUint64(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeUint64(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeUint64(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadBool(v *bool, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeBool(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeBool(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeBool(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadFloat32(v *float32, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeFloat32(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeFloat32(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeFloat32(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadFloat64(v *float64, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeFloat64(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeFloat64(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeFloat64(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadString(v *string, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeString(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeString(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeString(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) ReadBytes(v *[]byte, targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return decodeBytes(rd.dec, v)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		dec := msgpack.NewDecoder(bytes.NewReader(b))
		return decodeBytes(dec, v)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return decodeBytes(rd.dec, v)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) BeginContainer(targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return rd.beginContainer(targetField)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		rd.dec.Reset(bytes.NewReader(b))
		return rd.beginContainer(targetField)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return rd.beginContainer(targetField)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) EndContainer() error {
	return rd.endContainer()
}

func (rd *msgpackAssocReader) BeginCollection(targetField string) error {
	if !rd.curr.started || !rd.curr.assoc {
		return rd.beginCollection(targetField)
	}

	if b, ok := rd.curr.values[targetField]; ok {
		rd.dec.Reset(bytes.NewReader(b))
		return rd.beginCollection(targetField)
	}

	for i := rd.curr.readCnt; i < rd.curr.length; i++ {
		field, err := rd.readField()
		if err != nil {
			return err
		}
		if field == targetField {
			rd.curr.readCnt = i + 1
			return rd.beginCollection(targetField)
		}

		raw, err := rd.dec.DecodeRaw()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.curr.values[field] = raw
		rd.curr.readCnt = i + 1
	}

	return FieldNotFound
}

func (rd *msgpackAssocReader) EndCollection() error {
	return rd.endContainer()
}

func (rd *msgpackAssocReader) ContainerSize() (int, error) {
	return rd.curr.length, nil
}

func (rd *msgpackAssocReader) IsContainerAssoc() (bool, error) {
	return rd.curr.assoc, nil
}

func (rd *msgpackAssocReader) Skip() error {
	return errors.WithStack(rd.dec.Skip())
}

func (rd *msgpackAssocReader) TryReadMask() (bool, FieldsMask, error) {
	if rd.curr.assoc {
		return false, FieldsMask{}, nil
	}

	maskLen, err := rd.dec.DecodeArrayLen()
	if err != nil {
		if err == io.EOF {
			return false, FieldsMask{}, nil
		}
		return false, FieldsMask{}, errors.WithStack(err)
	}

	var mask FieldsMask
	for i := 0; i < maskLen; i++ {
		maskPart, err := rd.dec.DecodeUint64()
		if err != nil {
			return false, FieldsMask{}, errors.WithStack(err)
		}
		mask.SetPartFromUint64(i, maskPart)
	}

	return true, mask, nil
}

func (rd *msgpackAssocReader) beginContainer(field string) error {
	code, err := rd.dec.PeekCode()
	if err != nil {
		return errors.WithStack(err)
	}

	switch {
	case code == msgpcode.Nil:
		if err := rd.dec.DecodeNil(); err != nil {
			return errors.WithStack(err)
		}
		rd.stack = append(rd.stack, rd.curr)
		rd.curr = assocReadContainer{
			started: true,
			length:  0,
			assoc:   true,
			values:  make(map[string]msgpack.RawMessage),
			reader:  rd.dec.Buffered(),
		}

	case msgpcode.IsFixedMap(code), code == msgpcode.Map16, code == msgpcode.Map32:
		l, err := rd.dec.DecodeMapLen()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.stack = append(rd.stack, rd.curr)
		rd.curr = assocReadContainer{
			started: true,
			length:  l,
			assoc:   true,
			values:  make(map[string]msgpack.RawMessage, l),
			reader:  rd.dec.Buffered(),
		}

	default:
		return errors.Errorf("field `%s` is not a map", field)
	}
	return nil
}

func (rd *msgpackAssocReader) beginCollection(field string) error {
	code, err := rd.dec.PeekCode()
	if err != nil {
		return errors.WithStack(err)
	}

	switch {
	case msgpcode.IsFixedArray(code), code == msgpcode.Array16, code == msgpcode.Array32:
		l, err := rd.dec.DecodeArrayLen()
		if err != nil {
			return errors.WithStack(err)
		}
		rd.stack = append(rd.stack, rd.curr)
		rd.curr = assocReadContainer{
			started: true,
			length:  l,
			assoc:   false,
			reader:  rd.dec.Buffered(),
		}

	default:
		return errors.Errorf("field `%s` is not an array", field)
	}
	return nil
}

func (rd *msgpackAssocReader) endContainer() error {
	if len(rd.stack) == 0 {
		return NoOpenContainer
	}
	rd.curr = rd.stack[len(rd.stack)-1]
	rd.stack = rd.stack[:len(rd.stack)-1]
	rd.dec.Reset(rd.curr.reader)
	return nil
}