/*
goredo -- djb's redo implementation on pure Go
Copyright (C) 2020-2023 Sergey Matveev <stargrave@stargrave.org>

This program 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, version 3 of the License.

This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
*/

// Inode metainformation

package main

import (
	"errors"
	"os"
	"strconv"

	"go.cypherpunks.ru/recfile"
	"golang.org/x/sys/unix"
)

type InodeTrustType int

//go:generate stringer -type=InodeTrustType
const (
	EnvInodeTrust = "REDO_INODE_TRUST"

	InodeTrustNone InodeTrustType = iota
	InodeTrustCtime
	InodeTrustMtime
)

var InodeTrust InodeTrustType

type Inode struct {
	Size      int64
	InodeNum  uint64
	CtimeSec  int64
	CtimeNsec int64
	MtimeSec  int64
	MtimeNsec int64
}

func (our *Inode) Equals(their *Inode) bool {
	if our.Size != their.Size {
		return false
	}
	if our.InodeNum != their.InodeNum {
		return false
	}
	switch InodeTrust {
	case InodeTrustCtime:
		if our.CtimeSec != their.CtimeSec || our.CtimeNsec != their.CtimeNsec {
			return false
		}
	case InodeTrustMtime:
		if our.MtimeSec == 0 || our.MtimeNsec == 0 {
			return false
		}
		if our.MtimeSec != their.MtimeSec || our.MtimeNsec != their.MtimeNsec {
			return false
		}
	}
	return true
}

func (inode *Inode) RecfileFields() []recfile.Field {
	return []recfile.Field{
		{Name: "Size", Value: strconv.FormatInt(inode.Size, 10)},
		{Name: "InodeNum", Value: strconv.FormatUint(inode.InodeNum, 10)},
		{Name: "CtimeSec", Value: strconv.FormatInt(inode.CtimeSec, 10)},
		{Name: "CtimeNsec", Value: strconv.FormatInt(inode.CtimeNsec, 10)},
		{Name: "MtimeSec", Value: strconv.FormatInt(inode.MtimeSec, 10)},
		{Name: "MtimeNsec", Value: strconv.FormatInt(inode.MtimeNsec, 10)},
	}
}

func inodeFromFileStat(fi os.FileInfo, stat unix.Stat_t) *Inode {
	ctimeSec, ctimeNsec := stat.Ctim.Unix()
	mtimeSec := fi.ModTime().Unix()
	mtimeNsec := fi.ModTime().UnixNano()
	return &Inode{
		Size:     fi.Size(),
		InodeNum: uint64(stat.Ino),
		CtimeSec: ctimeSec, CtimeNsec: ctimeNsec,
		MtimeSec: mtimeSec, MtimeNsec: mtimeNsec,
	}
}

func inodeFromFileByFd(fd *os.File) (*Inode, error) {
	fi, err := fd.Stat()
	if err != nil {
		return nil, err
	}
	var stat unix.Stat_t
	err = unix.Fstat(int(fd.Fd()), &stat)
	if err != nil {
		return nil, err
	}
	return inodeFromFileStat(fi, stat), nil
}

func inodeFromFileByPath(p string) (*Inode, error) {
	fi, err := os.Stat(p)
	if err != nil {
		return nil, err
	}
	var stat unix.Stat_t
	err = unix.Stat(p, &stat)
	if err != nil {
		return nil, err
	}
	return inodeFromFileStat(fi, stat), nil
}

func inodeFromRec(m map[string]string) (*Inode, error) {
	size := m["Size"]
	inodeNum := m["InodeNum"]
	ctimeSec := m["CtimeSec"]
	ctimeNsec := m["CtimeNsec"]
	mtimeSec := m["MtimeSec"]
	mtimeNsec := m["MtimeNsec"]
	if size == "" {
		return nil, errors.New("Size is missing")
	}
	if ctimeSec == "" {
		return nil, errors.New("CtimeSec is missing")
	}
	if ctimeNsec == "" {
		return nil, errors.New("CtimeNsec is missing")
	}
	inode := Inode{}
	var err error
	inode.Size, err = strconv.ParseInt(size, 10, 64)
	if err != nil {
		return nil, err
	}
	if inodeNum != "" {
		inode.InodeNum, err = strconv.ParseUint(inodeNum, 10, 64)
		if err != nil {
			return nil, err
		}
	}
	inode.CtimeSec, err = strconv.ParseInt(ctimeSec, 10, 64)
	if err != nil {
		return nil, err
	}
	inode.CtimeNsec, err = strconv.ParseInt(ctimeNsec, 10, 64)
	if err != nil {
		return nil, err
	}
	if mtimeSec != "" {
		if mtimeNsec == "" {
			return nil, errors.New("MtimeNsec is missing")
		}
		inode.MtimeSec, err = strconv.ParseInt(mtimeSec, 10, 64)
		if err != nil {
			return nil, err
		}
		inode.MtimeNsec, err = strconv.ParseInt(mtimeNsec, 10, 64)
		if err != nil {
			return nil, err
		}
	}
	return &inode, nil
}