/* Copyright (C) 2021 Nicolas Peugnet <n.peugnet@free.fr>

   This file is part of dna-backup.

   dna-backup is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   dna-backup is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with dna-backup.  If not, see <https://www.gnu.org/licenses/>. */

package repo

import (
	"bytes"
	"fmt"
	"io"
	"path/filepath"
)

type Chunk interface {
	Reader() io.ReadSeeker
	Len() int
}

type IdentifiedChunk interface {
	Chunk
	GetId() *ChunkId
}

type BufferedChunk interface {
	Chunk
	Bytes() []byte
}

type RepoChunk interface {
	Chunk
	SetRepo(r *Repo)
}

type ChunkId struct {
	Ver int
	Idx uint64
}

func (i *ChunkId) Path(repo string) string {
	return filepath.Join(repo, fmt.Sprintf(versionFmt, i.Ver), chunksName, fmt.Sprintf(chunkIdFmt, i.Idx))
}

func NewStoredChunk(repo *Repo, id *ChunkId) *StoredChunk {
	return &StoredChunk{repo: repo, Id: id}
}

type StoredChunk struct {
	repo *Repo
	Id   *ChunkId
}

func (c *StoredChunk) GetId() *ChunkId {
	return c.Id
}

func (c *StoredChunk) SetRepo(r *Repo) {
	c.repo = r
}

func (c *StoredChunk) Reader() io.ReadSeeker {
	// log.Printf("Chunk %d: Reading from file\n", c.id)
	return c.repo.LoadChunkContent(c.Id)
}

func (c *StoredChunk) Len() int {
	return c.repo.chunkSize
}

func NewTempChunk(value []byte) *TempChunk {
	return &TempChunk{Value: value}
}

type TempChunk struct {
	Value []byte
}

func (c *TempChunk) Reader() io.ReadSeeker {
	return bytes.NewReader(c.Value)
}

func (c *TempChunk) Len() int {
	return len(c.Value)
}

func (c *TempChunk) Bytes() []byte {
	return c.Value
}

func (c *TempChunk) AppendFrom(r io.Reader) {
	buff, err := io.ReadAll(r)
	if err != nil {
		println("Chunk: error appending to temp chunk:", err)
	}
	c.Value = append(c.Value, buff...)
}

type DeltaChunk struct {
	repo   *Repo
	Source *ChunkId
	Patch  []byte
	Size   int
}

func (c *DeltaChunk) SetRepo(r *Repo) {
	c.repo = r
}

func (c *DeltaChunk) Reader() io.ReadSeeker {
	var buff bytes.Buffer
	c.repo.Patcher().Patch(c.repo.LoadChunkContent(c.Source), &buff, bytes.NewReader(c.Patch))
	return bytes.NewReader(buff.Bytes())
}

// TODO: Maybe return the size of the patch instead ?
func (c *DeltaChunk) Len() int {
	return c.Size
}