// Config: parse permissions.yaml

// SPDX-License-Identifier: GPL-3.0-or-later
// Copyright (C) 2021-2024  Simon Ruderich

package config

import (
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"strconv"
	"strings"

	"gopkg.in/yaml.v2"

	"ruderich.org/simon/safcm"
)

func LoadPermissions(group string, files map[string]*safcm.File) error {
	path := filepath.Join(group, "permissions.yaml")

	var cfg map[string]string
	x, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}
	err = yaml.UnmarshalStrict(x, &cfg)
	if err != nil {
		return fmt.Errorf("%s: failed to load: %v", path, err)
	}

	for p, x := range cfg {
		_, ok := files[p]
		if !ok {
			return fmt.Errorf("%s: %q does not exist in files/",
				path, p)
		}

		xs := strings.Fields(x)
		if len(xs) != 1 && len(xs) != 3 {
			return fmt.Errorf("%s: invalid line %q "+
				"(expected <perm> [<user> <group>])",
				path, x)
		}
		perm, err := strconv.ParseInt(xs[0], 8, 32)
		if err != nil {
			return fmt.Errorf("%s: invalid permission %q "+
				"(expected e.g. %q or %q)",
				path, xs[0], "0644", "01777")
		}
		if perm < 0 || perm > 07777 {
			return fmt.Errorf("%s: invalid permission %#o "+
				"(expected e.g. %#o or %#o)",
				path, perm, 0644, 01777)
		}

		file := files[p]
		// Sanity check
		if file.Mode.Perm()&0111 != 0 && perm&0111 == 0 {
			return fmt.Errorf(
				"%s: %q: trying to remove +x from file, "+
					"manually chmod -x in files/",
				path, p)
		}
		file.Mode = file.Mode.Type() | FullPermToFileMode(int(perm))
		if len(xs) == 3 {
			file.User = xs[1]
			file.Group = xs[2]
		}
	}

	return nil
}

func FileModeToFullPerm(mode fs.FileMode) int {
	perm := mode.Perm()
	if mode&fs.ModeSticky != 0 {
		perm |= 01000
	}
	if mode&fs.ModeSetgid != 0 {
		perm |= 02000
	}
	if mode&fs.ModeSetuid != 0 {
		perm |= 04000
	}
	return int(perm)
}

func FullPermToFileMode(perm int) fs.FileMode {
	mode := fs.FileMode(perm & 0777)
	if perm&01000 != 0 {
		mode |= fs.ModeSticky
	}
	if perm&02000 != 0 {
		mode |= fs.ModeSetgid
	}
	if perm&04000 != 0 {
		mode |= fs.ModeSetuid
	}
	return mode
}