/*
 * Copyright (c) SAS Institute, Inc.
 *
 * 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 cpio

import (
	"fmt"
	"io"
	"strconv"
)

// reference http://people.freebsd.org/~kientzle/libarchive/man/cpio.5.txt

const (
	cpio_newc_header_length = 110
	cpio_newc_magic         = "070701"
	cpio_stripped_magic     = "07070X"
)

type Cpio_newc_header struct {
	c_magic     string
	c_ino       int
	c_mode      int
	c_uid       int
	c_gid       int
	c_nlink     int
	c_mtime     int
	c_filesize  int
	c_devmajor  int
	c_devminor  int
	c_rdevmajor int
	c_rdevminor int
	c_namesize  int
	c_check     int

	stripped bool
	filename string
	index    int
	size64   int64
}

type binaryReader struct {
	r   io.Reader
	buf [8]byte
}

func (br *binaryReader) Read16(buf *int) error {
	bb := br.buf[:8]
	if _, err := io.ReadFull(br.r, bb); err != nil {
		return err
	}
	i, err := strconv.ParseInt(string(bb), 16, 0)
	if err != nil {
		return err
	}
	*buf = int(i)
	return nil
}

func readHeader(r io.Reader) (*Cpio_newc_header, error) {
	logger.Debug("reading header")
	hdr := Cpio_newc_header{}
	br := binaryReader{r: r}

	magic := make([]byte, 6)
	if _, err := io.ReadFull(r, magic); err != nil {
		return nil, err
	}
	if string(magic) == cpio_stripped_magic {
		return readStrippedHeader(br)
	} else if string(magic) != cpio_newc_magic {
		logger.Debugf("bad magic: %s", string(magic))
		return nil, fmt.Errorf("bad magic")
	}
	hdr.c_magic = cpio_newc_magic

	if err := br.Read16(&hdr.c_ino); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_mode); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_uid); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_gid); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_nlink); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_mtime); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_filesize); err != nil {
		return nil, err
	}
	hdr.size64 = int64(hdr.c_filesize)
	if err := br.Read16(&hdr.c_devmajor); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_devminor); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_rdevmajor); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_rdevminor); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_namesize); err != nil {
		return nil, err
	}
	if err := br.Read16(&hdr.c_check); err != nil {
		return nil, err
	}
	dumpHeader(&hdr)

	return &hdr, nil
}

func readStrippedHeader(br binaryReader) (*Cpio_newc_header, error) {
	hdr := &Cpio_newc_header{
		c_magic:  cpio_stripped_magic,
		stripped: true,
	}
	if err := br.Read16(&hdr.index); err != nil {
		return nil, err
	}
	logger.Debugf("stripped header %d\n", hdr.index)
	return hdr, nil
}

func dumpHeader(hdr *Cpio_newc_header) {
	logger.Debugf("header %+v", hdr)
}

func (hdr *Cpio_newc_header) Magic() string {
	return hdr.c_magic
}

func (hdr *Cpio_newc_header) Ino() int {
	return hdr.c_ino
}

func (hdr *Cpio_newc_header) Mode() int {
	return hdr.c_mode
}

func (hdr *Cpio_newc_header) Uid() int {
	return hdr.c_uid
}

func (hdr *Cpio_newc_header) Gid() int {
	return hdr.c_gid
}

func (hdr *Cpio_newc_header) Nlink() int {
	return hdr.c_nlink
}

func (hdr *Cpio_newc_header) Mtime() int {
	return hdr.c_mtime
}

func (hdr *Cpio_newc_header) Filesize() int {
	return hdr.c_filesize
}

func (hdr *Cpio_newc_header) Devmajor() int {
	return hdr.c_devmajor
}

func (hdr *Cpio_newc_header) Devminor() int {
	return hdr.c_devminor
}

func (hdr *Cpio_newc_header) Rdevmajor() int {
	return hdr.c_rdevmajor
}

func (hdr *Cpio_newc_header) Rdevminor() int {
	return hdr.c_rdevminor
}

func (hdr *Cpio_newc_header) Namesize() int {
	return hdr.c_namesize
}

func (hdr *Cpio_newc_header) Check() int {
	return hdr.c_check
}

func (hdr *Cpio_newc_header) Filename() string {
	return hdr.filename
}

// stripped header functions

func (hdr *Cpio_newc_header) IsStripped() bool {
	return hdr.stripped
}

func (hdr *Cpio_newc_header) Index() int {
	return hdr.index
}

func (hdr *Cpio_newc_header) Filesize64() int64 {
	return hdr.size64
}