/*
Copyright The ORAS Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package content

import (
	"errors"

	"github.com/opencontainers/go-digest"
)

type WriterOpts struct {
	InputHash           *digest.Digest
	OutputHash          *digest.Digest
	Blocksize           int
	MultiWriterIngester bool
	IgnoreNoName        bool
}

type WriterOpt func(*WriterOpts) error

func DefaultWriterOpts() WriterOpts {
	return WriterOpts{
		InputHash:    nil,
		OutputHash:   nil,
		Blocksize:    DefaultBlocksize,
		IgnoreNoName: true,
	}
}

// WithInputHash provide the expected input hash to a writer. Writers
// may suppress their own calculation of a hash on the stream, taking this
// hash instead. If the Writer processes the data before passing it on to another
// Writer layer, this is the hash of the *input* stream.
//
// To have a blank hash, use WithInputHash(BlankHash).
func WithInputHash(hash digest.Digest) WriterOpt {
	return func(w *WriterOpts) error {
		w.InputHash = &hash
		return nil
	}
}

// WithOutputHash provide the expected output hash to a writer. Writers
// may suppress their own calculation of a hash on the stream, taking this
// hash instead. If the Writer processes the data before passing it on to another
// Writer layer, this is the hash of the *output* stream.
//
// To have a blank hash, use WithInputHash(BlankHash).
func WithOutputHash(hash digest.Digest) WriterOpt {
	return func(w *WriterOpts) error {
		w.OutputHash = &hash
		return nil
	}
}

// WithBlocksize set the blocksize used by the processor of data.
// The default is DefaultBlocksize, which is the same as that used by io.Copy.
// Includes a safety check to ensure the caller doesn't actively set it to <= 0.
func WithBlocksize(blocksize int) WriterOpt {
	return func(w *WriterOpts) error {
		if blocksize <= 0 {
			return errors.New("blocksize must be greater than or equal to 0")
		}
		w.Blocksize = blocksize
		return nil
	}
}

// WithMultiWriterIngester the passed ingester also implements MultiWriter
// and should be used as such. If this is set to true, but the ingester does not
// implement MultiWriter, calling Writer should return an error.
func WithMultiWriterIngester() WriterOpt {
	return func(w *WriterOpts) error {
		w.MultiWriterIngester = true
		return nil
	}
}

// WithErrorOnNoName some ingesters, when creating a Writer, do not return an error if
// the descriptor does not have a valid name on the descriptor. Passing WithErrorOnNoName
// tells the writer to return an error instead of passing the data to a nil writer.
func WithErrorOnNoName() WriterOpt {
	return func(w *WriterOpts) error {
		w.IgnoreNoName = false
		return nil
	}
}

// WithIgnoreNoName some ingesters, when creating a Writer, return an error if
// the descriptor does not have a valid name on the descriptor. Passing WithIgnoreNoName
// tells the writer not to return an error, but rather to pass the data to a nil writer.
//
// Deprecated: Use WithErrorOnNoName
func WithIgnoreNoName() WriterOpt {
	return func(w *WriterOpts) error {
		w.IgnoreNoName = true
		return nil
	}
}