package structs

import (
	"bufio"
	"fmt"
	"io"

	"github.com/tuneinsight/lattigo/v4/utils/buffer"
)

type Vector[T any] []T

// CopyNew creates a copy of the oject.
func (v Vector[T]) CopyNew() *Vector[T] {

	if c, isCopiable := any(new(T)).(CopyNewer[T]); !isCopiable {
		panic(fmt.Errorf("vector component of type %T does not comply to %T", new(T), c))
	}

	vcpy := Vector[T](make([]T, len(v)))
	for i := range v {
		vcpy[i] = *any(&v[i]).(CopyNewer[T]).CopyNew()
	}
	return &vcpy
}

// BinarySize returns the serialized size of the object in bytes.
func (v Vector[T]) BinarySize() (size int) {

	var st *T
	if s, isSizable := any(st).(BinarySizer); !isSizable {
		panic(fmt.Errorf("vector component of type %T does not comply to %T", st, s))
	}

	size += 8
	for i := range v {
		size += any(&v[i]).(BinarySizer).BinarySize()
	}
	return
}

// WriteTo writes the object on an io.Writer. It implements the io.WriterTo
// interface, and will write exactly object.BinarySize() bytes on w.
//
// Unless w implements the buffer.Writer interface (see lattigo/utils/buffer/writer.go),
// it will be wrapped into a bufio.Writer. Since this requires allocations, it
// is preferable to pass a buffer.Writer directly:
//
//   - When writing multiple times to a io.Writer, it is preferable to first wrap the
//     io.Writer in a pre-allocated bufio.Writer.
//   - When writing to a pre-allocated var b []byte, it is preferable to pass
//     buffer.NewBuffer(b) as w (see lattigo/utils/buffer/buffer.go).
func (v Vector[T]) WriteTo(w io.Writer) (n int64, err error) {

	var o *T
	if wt, isWritable := any(o).(io.WriterTo); !isWritable {
		return 0, fmt.Errorf("vector component of type %T does not comply to %T", o, wt)
	}

	switch w := w.(type) {
	case buffer.Writer:

		var inc int64
		if inc, err = buffer.WriteInt(w, len(v)); err != nil {
			return inc, err
		}
		n += inc

		for i := range v {
			if inc, err = any(&v[i]).(io.WriterTo).WriteTo(w); err != nil {
				return n + inc, err
			}
			n += inc
		}

		return n, w.Flush()

	default:
		return v.WriteTo(bufio.NewWriter(w))
	}
}

// ReadFrom reads on the object from an io.Writer. It implements the
// io.ReaderFrom interface.
//
// Unless r implements the buffer.Reader interface (see see lattigo/utils/buffer/reader.go),
// it will be wrapped into a bufio.Reader. Since this requires allocation, it
// is preferable to pass a buffer.Reader directly:
//
//   - When reading multiple values from a io.Reader, it is preferable to first
//     first wrap io.Reader in a pre-allocated bufio.Reader.
//   - When reading from a var b []byte, it is preferable to pass a buffer.NewBuffer(b)
//     as w (see lattigo/utils/buffer/buffer.go).
func (v *Vector[T]) ReadFrom(r io.Reader) (n int64, err error) {

	var rt *T
	if r, isReadable := any(rt).(io.ReaderFrom); !isReadable {
		return 0, fmt.Errorf("vector component of type %T does not comply to %T", rt, r)
	}

	switch r := r.(type) {
	case buffer.Reader:
		var size int
		var inc int64

		if inc, err = buffer.ReadInt(r, &size); err != nil {
			return inc, fmt.Errorf("cannot read vector size: %w", err)
		}
		n += inc

		if cap(*v) < size {
			*v = make([]T, size)
		}
		*v = (*v)[:size]

		for i := range *v {
			if inc, err = any(&(*v)[i]).(io.ReaderFrom).ReadFrom(r); err != nil {
				return n + inc, err
			}
			n += inc
		}

		return n, nil

	default:
		return v.ReadFrom(bufio.NewReader(r))
	}
}

// MarshalBinary encodes the object into a binary form on a newly allocated slice of bytes.
func (v Vector[T]) MarshalBinary() (p []byte, err error) {
	buf := buffer.NewBufferSize(v.BinarySize())
	_, err = v.WriteTo(buf)
	return buf.Bytes(), err
}

// UnmarshalBinary decodes a slice of bytes generated by
// MarshalBinary or WriteTo on the object.
func (v *Vector[T]) UnmarshalBinary(p []byte) (err error) {
	_, err = v.ReadFrom(buffer.NewBuffer(p))
	return
}

type Equatable[T any] interface {
	Equal(*T) bool
}

func (v Vector[T]) Equal(other Vector[T]) bool {

	if d, isEquatable := any(new(T)).(Equatable[T]); !isEquatable {
		panic(fmt.Errorf("vector component of type %T does not comply to %T", new(T), d))
	}

	isEqual := true
	for i, v := range v {
		/* #nosec G601 -- Implicit memory aliasing in for loop acknowledged */
		isEqual = isEqual && any(&v).(Equatable[T]).Equal(&other[i])
	}

	return isEqual
}