// apparmor.d - Full set of apparmor profiles
// Copyright (C) 2023 Alexandre Pujol <alexandre@pujol.io>
// SPDX-License-Identifier: GPL-2.0-only

package prebuild

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/arduino/go-paths-helper"
	"github.com/roddhjav/apparmor.d/pkg/logging"
)

// Prepare the build directory with the following tasks
var Prepares = []PrepareFunc{
	Synchronise,
	Ignore,
	Merge,
	Configure,
	SetFlags,
}

type PrepareFunc func() error

// Initialize a new clean apparmor.d build directory
func Synchronise() error {
	dirs := paths.PathList{RootApparmord, Root.Join("root"), Root.Join("systemd")}
	for _, dir := range dirs {
		if err := dir.RemoveAll(); err != nil {
			return err
		}
	}
	for _, name := range []string{"apparmor.d", "root"} {
		if err := copyTo(paths.New(name), Root.Join(name)); err != nil {
			return err
		}
	}
	logging.Success("Initialize a new clean apparmor.d build directory")
	return nil
}

// Ignore profiles and files as defined in dists/ignore/
func Ignore() error {
	for _, name := range []string{"main.ignore", Distribution + ".ignore"} {
		path := DistDir.Join("ignore", name)
		if !path.Exist() {
			continue
		}
		lines, _ := path.ReadFileAsLines()
		for _, line := range lines {
			if strings.HasPrefix(line, "#") || line == "" {
				continue
			}
			profile := Root.Join(line)
			if profile.NotExist() {
				files, err := RootApparmord.ReadDirRecursiveFiltered(nil, paths.FilterNames(line))
				if err != nil {
					return err
				}
				for _, path := range files {
					if err := path.RemoveAll(); err != nil {
						return err
					}
				}
			} else {
				if err := profile.RemoveAll(); err != nil {
					return err
				}
			}
		}
		logging.Success("Ignore profiles/files in %s", path)
	}
	return nil
}

// Merge all profiles in a new apparmor.d directory
func Merge() error {
	var dirToMerge = []string{
		"groups/*/*", "groups",
		"profiles-*-*/*", "profiles-*",
	}

	idx := 0
	for idx < len(dirToMerge)-1 {
		dirMoved, dirRemoved := dirToMerge[idx], dirToMerge[idx+1]
		files, err := filepath.Glob(RootApparmord.Join(dirMoved).String())
		if err != nil {
			return err
		}
		for _, file := range files {
			err := os.Rename(file, RootApparmord.Join(filepath.Base(file)).String())
			if err != nil {
				return err
			}
		}

		files, err = filepath.Glob(RootApparmord.Join(dirRemoved).String())
		if err != nil {
			return err
		}
		for _, file := range files {
			if err := paths.New(file).RemoveAll(); err != nil {
				return err
			}
		}
		idx = idx + 2
	}
	logging.Success("Merge all profiles")
	return nil
}

// Set the distribution specificities
func Configure() (err error) {
	switch Distribution {
	case "arch", "opensuse":

	case "debian", "ubuntu", "whonix":
		// Copy Ubuntu specific profiles
		if err := copyTo(DistDir.Join("ubuntu"), RootApparmord); err != nil {
			return err
		}

	default:
		return fmt.Errorf("%s is not a supported distribution", Distribution)

	}
	return err
}

// Set flags on some profiles according to manifest defined in `dists/flags/`
func SetFlags() error {
	for _, name := range []string{"main.flags", Distribution + ".flags"} {
		path := FlagDir.Join(name)
		if !path.Exist() {
			continue
		}
		lines, _ := path.ReadFileAsLines()
		for _, line := range lines {
			if strings.HasPrefix(line, "#") || line == "" {
				continue
			}
			manifest := strings.Split(line, " ")
			profile := manifest[0]
			file := RootApparmord.Join(profile)
			if !file.Exist() {
				logging.Warning("Profile %s not found", profile)
				continue
			}

			// If flags is set, overwrite profile flag
			if len(manifest) > 1 {
				flags := " flags=(" + manifest[1] + ") {"
				content, err := file.ReadFile()
				if err != nil {
					return err
				}

				// Remove all flags definition, then set manifest' flags
				res := regFlags.ReplaceAllLiteralString(string(content), "")
				res = regProfileHeader.ReplaceAllLiteralString(res, flags)
				if err := file.WriteFile([]byte(res)); err != nil {
					return err
				}
			}
		}
		logging.Success("Set profile flags from %s", path)
	}
	return nil
}

// Set systemd unit drop in files to ensure some service start after apparmor
func SetDefaultSystemd() error {
	return copyTo(paths.New("systemd/default/"), Root.Join("systemd"))
}

// Set AppArmor for (experimental) full system policy.
// See https://apparmor.pujol.io/development/structure/#full-system-policy
func SetFullSystemPolicy() error {
	// Install full system policy profiles
	for _, name := range []string{"systemd", "systemd-user"} {
		err := paths.New("apparmor.d/groups/_full/" + name).CopyTo(RootApparmord.Join(name))
		if err != nil {
			return err
		}
	}

	// Set systemd profile name
	path := paths.New("apparmor.d/tunables/multiarch.d/apparmor.d")
	content, err := path.ReadFile()
	if err != nil {
		return err
	}
	res := strings.Replace(string(content), "@{systemd}=unconfined", "@{systemd}=systemd", -1)
	if err := path.WriteFile([]byte(res)); err != nil {
		return err
	}

	// Set systemd unit drop-in files
	if err := copyTo(paths.New("systemd/full/"), Root.Join("systemd")); err != nil {
		return err
	}

	logging.Success("Configure AppArmor for full system policy")
	return nil
}