// goredo -- djb's redo implementation on pure Go
// Copyright (C) 2020-2024 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/>.

package main

import (
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"path"
	"strings"
)

const (
	CleanupFull = "full"
	CleanupLog  = "log"
	CleanupTmp  = "tmp"
	CleanupLock = "lock"
)

var DryRun *bool

func init() {
	if CmdName() != CmdNameRedoCleanup {
		return
	}
	DryRun = flag.Bool("n", false, "do no delete files during cleanup, just show them")
}

func redoDirClean(root, what string) error {
	root = mustAbs(root)
	dir, err := os.Open(root)
	if err != nil {
		return ErrLine(err)
	}
	defer dir.Close()
	for {
		entries, err := dir.ReadDir(1 << 10)
		if err != nil {
			if err == io.EOF {
				break
			}
			return ErrLine(err)
		}
		var pth string
		for _, entry := range entries {
			pth = cwdMustRel(root, entry.Name())
			switch what {
			case CleanupLog:
				if strings.HasSuffix(entry.Name(), LogSuffix) ||
					strings.HasSuffix(entry.Name(), LogRecSuffix) {
					fmt.Println(pth)
					if !*DryRun {
						if err = os.Remove(pth); err != nil {
							return ErrLine(err)
						}
					}
				}
			case CleanupLock:
				if strings.HasSuffix(entry.Name(), LockSuffix) {
					fmt.Println(pth)
					if !*DryRun {
						if err = os.Remove(pth); err != nil {
							return ErrLine(err)
						}
					}
				}
			case CleanupTmp:
				if strings.HasPrefix(entry.Name(), TmpPrefix) {
					fmt.Println(pth)
					if !*DryRun {
						if err = os.Remove(pth); err != nil {
							return ErrLine(err)
						}
					}
				}
			default:
				log.Fatal("unknown cleanup target")
			}
		}
	}
	return nil
}

func cleanupWalker(root, what string) error {
	root = mustAbs(root)
	dir, err := os.Open(root)
	if err != nil {
		return ErrLine(err)
	}
	defer dir.Close()
	for {
		entries, err := dir.ReadDir(1 << 10)
		if err != nil {
			if err == io.EOF {
				break
			}
			return ErrLine(err)
		}
		for _, entry := range entries {
			pth := path.Join(root, entry.Name())
			pthRel := cwdMustRel(root, entry.Name())
			if entry.IsDir() {
				if entry.Name() == RedoDir {
					if what == CleanupFull {
						fmt.Println(pthRel)
						if !*DryRun {
							err = ErrLine(os.RemoveAll(pth))
						}
					} else {
						err = redoDirClean(pth, what)
					}
				} else if (what == CleanupTmp || what == CleanupFull) &&
					strings.HasPrefix(entry.Name(), TmpPrefix) {
					fmt.Println(pthRel)
					if !*DryRun {
						err = ErrLine(os.RemoveAll(pth))
					}
				} else {
					err = cleanupWalker(pth, what)
				}
				if err != nil {
					return err
				}
				continue
			}
			if (what == CleanupTmp || what == CleanupFull) &&
				strings.HasPrefix(entry.Name(), TmpPrefix) {
				fmt.Println(pthRel)
				if !*DryRun {
					if err = os.Remove(pth); err != nil {
						return ErrLine(err)
					}
				}
			}
		}
	}
	return nil
}