package memory

import (
	"bytes"
	"io/ioutil"

	"gopkg.in/src-d/go-git.v3/core"
)

// Object on memory core.Object implementation
type Object struct {
	t    core.ObjectType
	h    core.Hash
	cont []byte
	sz   int64
}

// NewObject creates a new object with the given type and content
func NewObject(typ core.ObjectType, size int64, cont []byte) *Object {
	return &Object{
		t:    typ,
		h:    core.ComputeHash(typ, cont),
		cont: cont,
		sz:   int64(len(cont)),
	}
}

// Hash return the object Hash, the hash is calculated on-the-fly the first
// time is called, the subsequent calls the same Hash is returned even if the
// type or the content has changed. The Hash is only generated if the size of
// the content is exactly the Object.Size
func (o *Object) Hash() core.Hash {
	if o.h == core.ZeroHash && int64(len(o.cont)) == o.sz {
		o.h = core.ComputeHash(o.t, o.cont)
	}

	return o.h
}

// Type return the core.ObjectType
func (o *Object) Type() core.ObjectType { return o.t }

// SetType sets the core.ObjectType
func (o *Object) SetType(t core.ObjectType) { o.t = t }

// Size return the size of the object
func (o *Object) Size() int64 { return o.sz }

// SetSize set the object size, the given size should be written afterwards
func (o *Object) SetSize(s int64) { o.sz = s }

// Content returns the contents of the object
func (o *Object) Content() []byte { return o.cont }

// Reader returns a core.ObjectReader used to read the object's content.
func (o *Object) Reader() (core.ObjectReader, error) {
	return ioutil.NopCloser(bytes.NewBuffer(o.cont)), nil
}

// Writer returns a core.ObjectWriter used to write the object's content.
func (o *Object) Writer() (core.ObjectWriter, error) {
	return o, nil
}

func (o *Object) Write(p []byte) (n int, err error) {
	o.cont = append(o.cont, p...)
	return len(p), nil
}

// Close releases any resources consumed by the object when it is acting as a
// core.ObjectWriter.
func (o *Object) Close() error { return nil }