// Config: load files/ directory tree

// Copyright (C) 2021  Simon Ruderich
//
// 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, either version 3 of the License, or
// (at your option) any later version.
//
// 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 config

import (
	"fmt"
	"io/fs"
	"os"
	slashpath "path"
	"path/filepath"
	"runtime"

	"ruderich.org/simon/safcm"
)

func LoadFiles(group string) (map[string]*safcm.File, error) {
	basePath := filepath.Join(group, "files")

	const errMsg = `

The actual permissions and user/group of files and directories are not used
(except for +x on files). 0644/0755 and current remote user/group is used per
default. Apply different file permissions via permissions.yaml. To prevent
confusion files must be manually chmodded 0644/0755 and directories 0755 or
via "safcm fixperms".
`

	// No permission checks on windows which doesn't track them.
	windows := runtime.GOOS == "windows"

	files := make(map[string]*safcm.File)
	err := filepath.WalkDir(basePath, func(path string, d fs.DirEntry,
		err error) error {

		if err != nil {
			return err
		}

		info, err := d.Info()
		if err != nil {
			return err
		}
		typ := info.Mode().Type()
		perm := FileModeToFullPerm(info.Mode())

		var data []byte
		// See errMsg above. If a user stores a file with stricter
		// permissions they could assume that these permissions are
		// respected. This is not the case.
		if typ == 0 /* regular file */ {
			if windows {
				perm = 0644
				// 0755 must be set via permissions.yaml if
				// windows is used
			}
			if perm != 0644 && perm != 0755 {
				return fmt.Errorf(
					"%q: invalid permissions %#o%s",
					path, perm, errMsg)
			}
			data, err = os.ReadFile(path)
			if err != nil {
				return err
			}
		} else if typ == fs.ModeDir {
			if windows {
				perm = 0755
			}
			if perm != 0755 {
				return fmt.Errorf(
					"%q: invalid permissions %#o%s",
					path, perm, errMsg)
			}
		} else if typ == fs.ModeSymlink {
			x, err := os.Readlink(path)
			if err != nil {
				return err
			}
			data = []byte(x)
			perm |= 0777 // see cmd/safcm-remote/sync/files.go
		} else {
			return fmt.Errorf("%q: file type not supported", path)
		}

		// Convert to absolute and slash-separated path as used on the
		// target host
		x, err := filepath.Rel(basePath, path)
		if err != nil {
			return err
		}
		x = slashpath.Join("/", filepath.ToSlash(x))

		files[x] = &safcm.File{
			Path: x,
			Mode: typ | (fs.FileMode(perm) & fs.ModePerm),
			Uid:  -1,
			Gid:  -1,
			Data: data,
		}
		return nil
	})
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, fmt.Errorf("%s: %v", group, err)
	}
	return files, nil
}