/*
 * fscrypt.go - File which starts up and runs the application. Initializes
 * information about the application like the name, version, author, etc...
 *
 * Copyright 2017 Google Inc.
 * Author: Joe Richey (joerichey@google.com)
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

/*
fscrypt is a command line tool for managing linux filesystem encryption.
*/

package main

import (
	"fmt"

	"github.com/google/fscrypt/filesystem"
	"github.com/google/fscrypt/security"
	"github.com/pkg/errors"

	"github.com/google/fscrypt/actions"

	"github.com/google/fscrypt/cmd"
)

// Arguments used in fscrypt commands.
var (
	unusedMountpointArg = &cmd.Argument{
		ArgName: "mountpoint",
		Usage:   "path to a mountpoint on which to setup fscrypt",
	}
	usedMountpointArg = &cmd.Argument{
		ArgName: "mountpoint",
		Usage:   "path to a mountpoint being used with fscrypt",
	}
	directoryToEncryptArg = &cmd.Argument{
		ArgName: "directory",
		Usage:   "path to an empty directory to encrypt with fscrypt",
	}
	encryptedPathArg = &cmd.Argument{
		ArgName: "path",
		Usage:   "file or directory encrypted with fscrypt",
	}
)

func main() { fscryptCommand.Run(fscryptHelpTextMap) }

var baseFlags = []cmd.Flag{cmd.VerboseFlag, cmd.QuietFlag, cmd.HelpFlag}

var fscryptCommand = cmd.Command{
	Title: "manage linux filesystem encryption",
	UsageLines: []string{
		fmt.Sprintf("<command> [arguments] [options] [%s|%s]",
			cmd.VerboseFlag, cmd.QuietFlag),
		cmd.VersionUsage,
	},
	SubCommands: []*cmd.Command{setupCommand, encryptCommand, unlockCommand,
		purgeCommand, statusCommand, metadataCommand, cmd.VersionCommand}, Flags: baseFlags,
	ManPage: &cmd.ManPage{Name: "fscrypt", Section: 8},
}

// setup performs global or per-filesystem initialization of fscrypt data.
var setupCommand = &cmd.Command{
	Name:  "setup",
	Title: "setup a system/filesystem to use fscrypt",
	UsageLines: []string{
		fmt.Sprintf("[options]"),
		fmt.Sprintf("%s [%s]", unusedMountpointArg, cmd.ForceFlag),
	},
	Arguments:    []*cmd.Argument{unusedMountpointArg},
	InheritFlags: true,
	Flags:        []cmd.Flag{timeTargetFlag, legacyFlag, cmd.ForceFlag},
	ManPage:      &cmd.ManPage{Name: "fscrypt-setup", Section: 8},
	Action:       setupAction,
}

func setupAction(c *cmd.Context) error {
	switch len(c.Args) {
	case 0:
		// Case (1) - global setup
		return createGlobalConfig(actions.ConfigFileLocation)
	case 1:
		// Case (2) - filesystem setup
		return setupFilesystem(c.Args[0])
	default:
		return cmd.CheckExpectedArgs(c, 1, true)
	}
}

// encrypt takes an empty directory, enables encryption, and unlocks it.
var encryptCommand = &cmd.Command{
	Name:         "encrypt",
	Title:        "start encrypting an empty directory",
	UsageLines:   []string{"???"}, // TODO(joerichey)
	Arguments:    []*cmd.Argument{directoryToEncryptArg},
	InheritFlags: true,
	Flags: []cmd.Flag{sourceFlag, nameFlag, protectorFlag, policyFlag,
		unlockWithFlag, keyFileFlag, userFlag, skipUnlockFlag},
	ManPage: &cmd.ManPage{Name: "fscrypt-encrypt", Section: 8},
	Action:  encryptAction,
}

func encryptAction(c *cmd.Context) error {
	if err := cmd.CheckExpectedArgs(c, 1, false); err != nil {
		return err
	}

	path := c.Args[0]
	if err := encryptPath(path); err != nil {
		return err
	}

	if !skipUnlockFlag.Value {
		fmt.Fprintf(cmd.Output, "%q is now encrypted, unlocked, and ready for use.\n", path)
		return nil
	}

	fmt.Fprintf(cmd.Output, "%q is now encrypted, but it is still locked.\n", path)
	fmt.Fprintf(cmd.Output, "It can be unlocked with: fscrypt unlock %q\n", path)
	return nil
}

// unlock takes an encrypted path and makes it available for reading/writing.
var unlockCommand = &cmd.Command{
	Name:         "unlock",
	Title:        "unlock an encrypted file or directory",
	UsageLines:   []string{"???"}, // TODO(joerichey)
	Arguments:    []*cmd.Argument{encryptedPathArg},
	InheritFlags: true,
	Flags:        []cmd.Flag{unlockWithFlag, keyFileFlag, userFlag},
	ManPage:      &cmd.ManPage{Name: "fscrypt-unlock", Section: 8},
	Action:       unlockAction,
}

func unlockAction(c *cmd.Context) error {
	if err := cmd.CheckExpectedArgs(c, 1, false); err != nil {
		return err
	}

	path := c.Args[0]
	if err := unlockPath(path); err != nil {
		return err
	}

	fmt.Fprintf(cmd.Output, "%q is now unlocked and ready for use.\n", path)
	return nil
}

// purge removes all the policy keys from the keyring (my require unmount).
var purgeCommand = &cmd.Command{
	Name:  "purge",
	Title: "remove a directory's encryption keys",
	UsageLines: []string{fmt.Sprintf("%s, [%s=false] [%s] [%s]",
		usedMountpointArg, dropCachesFlag, userFlag, cmd.ForceFlag)},
	Arguments:    []*cmd.Argument{usedMountpointArg},
	InheritFlags: true,
	Flags:        []cmd.Flag{dropCachesFlag, userFlag, cmd.ForceFlag},
	ManPage:      &cmd.ManPage{Name: "fscrypt-purge", Section: 8},
	Action:       purgeAction,
}

func purgeAction(c *cmd.Context) error {
	if err := cmd.CheckExpectedArgs(c, 1, false); err != nil {
		return err
	}
	if dropCachesFlag.Value {
		if cmd.CheckIfRoot() != nil {
			return ErrDropCachesPerm
		}
	}

	targetUser, err := parseUserFlag(true)
	if err != nil {
		return err
	}
	ctx, err := actions.NewContextFromMountpoint(c.Args[0], targetUser)
	if err != nil {
		return err
	}

	question := fmt.Sprintf("Purge all policy keys from %q", ctx.Mount.Path)
	if dropCachesFlag.Value {
		question += " and drop global inode cache"
	}
	warning := "Encrypted data on this filesystem will be inaccessible until unlocked again!!"
	if err = cmd.AskConfirmation(question+"?", warning, false); err != nil {
		return err
	}
	if err = actions.PurgeAllPolicies(ctx); err != nil {
		return err
	}
	fmt.Fprintf(cmd.Output, "Policies purged from filesystem %q.\n", ctx.Mount.Path)

	if !dropCachesFlag.Value {
		fmt.Fprintf(cmd.Output, "Filesystem %q should now be unmounted.\n", ctx.Mount.Path)
		return nil
	}
	if err = security.DropFilesystemCache(); err != nil {
		return err
	}
	fmt.Fprintln(cmd.Output, "Encrypted data removed from filesystem cache.")
	return nil
}

// status is a command that gets info about the system, a mountpoint, or a path.
var statusCommand = &cmd.Command{
	Name:       "status",
	Title:      "get the status of the system or a path",
	UsageLines: []string{"", usedMountpointArg.String(), encryptedPathArg.String()},
	Arguments:  []*cmd.Argument{usedMountpointArg, encryptedPathArg},
	Flags:      []cmd.Flag{cmd.VerboseFlag, cmd.HelpFlag},
	ManPage:    &cmd.ManPage{Name: "fscrypt-status", Section: 8},
	Action:     statusAction,
}

func statusAction(c *cmd.Context) error {
	switch len(c.Args) {
	case 0:
		// Case (1) - global status
		return writeGlobalStatus()
	case 1:
		path := c.Args[0]
		ctx, mntErr := actions.NewContextFromMountpoint(path, nil)

		switch errors.Cause(mntErr) {
		case nil:
			// Case (2) - mountpoint status
			return writeFilesystemStatus(ctx)
		case filesystem.ErrNotAMountpoint:
			// Case (3) - file or directory status
			return writePathStatus(path)
		default:
			return mntErr
		}
	default:
		return cmd.CheckExpectedArgs(c, 1, true)
	}
}

// metadata is a collection of commands for manipulating the metadata files.
var metadataCommand = &cmd.Command{
	Name:  "metadata",
	Title: "manipulate fscrypt metadata directly",
	UsageLines: []string{fmt.Sprintf("<command> [options] [%s] [%s]",
		protectorFlag, policyFlag)},
	SubCommands: []*cmd.Command{createCommand, destroyCommand, changeCommand,
		addProtectorCommand, removeProtectorCommand, dumpCommand},
	InheritFlags: true,
	Flags:        []cmd.Flag{protectorFlag, policyFlag},
	ManPage:      &cmd.ManPage{Name: "fscrypt-metadata", Section: 8},
}

var createCommand = &cmd.Command{
	Name:  "create",
	Title: "manually create metadata on a filesystem",
	UsageLines: []string{
		fmt.Sprintf("protector %s", usedMountpointArg),
		fmt.Sprintf("policy    %s %s", usedMountpointArg, protectorFlag),
	},
	SubCommands: []*cmd.Command{createProtectorCommand, createPolicyCommand},
	Arguments:   []*cmd.Argument{usedMountpointArg},
	Flags:       baseFlags,
}

var createProtectorCommand = &cmd.Command{
	Name:             "protector",
	Title:            "create a protector without creating a policy",
	UsageLines:       []string{"???"}, // TODO(joerichey)
	InheritArguments: true,
	InheritFlags:     true,
	Flags:            []cmd.Flag{sourceFlag, nameFlag, keyFileFlag, userFlag},
	Action:           createProtectorAction,
}

func createProtectorAction(c *cmd.Context) error {
	if err := cmd.CheckExpectedArgs(c, 1, false); err != nil {
		return err
	}

	targetUser, err := parseUserFlag(true)
	if err != nil {
		return err
	}
	ctx, err := actions.NewContextFromMountpoint(c.Args[0], targetUser)
	if err != nil {
		return err
	}

	prompt := fmt.Sprintf("Create new protector on %q", ctx.Mount.Path)
	if err := cmd.AskConfirmation(prompt, "", true); err != nil {
		return err
	}

	protector, err := createProtectorFromContext(ctx)
	if err != nil {
		return err
	}
	protector.Lock()

	fmt.Fprintf(cmd.Output, "Protector %s created on filesystem %q.\n",
		protector.Descriptor(), ctx.Mount.Path)
	return nil
}

var createPolicyCommand = &cmd.Command{
	Name:  "policy",
	Title: "create a policy using an existing protector",
	UsageLines: []string{fmt.Sprintf("%s %s [%s]",
		usedMountpointArg, protectorFlag, keyFileFlag)},
	InheritArguments: true,
	InheritFlags:     true,
	Flags:            []cmd.Flag{protectorFlag, keyFileFlag},
	Action:           createPolicyAction,
}

func createPolicyAction(c *cmd.Context) error {
	if err := cmd.CheckExpectedArgs(c, 1, false); err != nil {
		return err
	}
	if err := cmd.CheckRequiredFlags([]*cmd.StringFlag{protectorFlag}); err != nil {
		return err
	}

	ctx, err := actions.NewContextFromMountpoint(c.Args[0], nil)
	if err != nil {
		return err
	}
	protector, err := getProtectorFromFlag(protectorFlag.Value, ctx.TargetUser)
	if err != nil {
		return err
	}
	if err := protector.Unlock(existingKeyFn); err != nil {
		return err
	}
	defer protector.Lock()

	prompt := fmt.Sprintf("Create new policy on %q", ctx.Mount.Path)
	if err := cmd.AskConfirmation(prompt, "", true); err != nil {
		return err
	}
	policy, err := actions.CreatePolicy(ctx, protector)
	if err != nil {
		return err
	}
	policy.Lock()

	fmt.Fprintf(cmd.Output, "Policy %s created on filesystem %q.\n",
		policy.Descriptor(), ctx.Mount.Path)
	return nil
}

var destroyCommand = &cmd.Command{
	Name:  "destroy",
	Title: "directly delete an existing protector or policy",
	UsageLines: []string{
		fmt.Sprintf("%s [%s]", protectorFlag, cmd.ForceFlag),
		fmt.Sprintf("%s [%s]", policyFlag, cmd.ForceFlag),
		fmt.Sprintf("%s [%s]", usedMountpointArg, cmd.ForceFlag),
	},
	Arguments:    []*cmd.Argument{usedMountpointArg},
	InheritFlags: true,
	Flags:        []cmd.Flag{cmd.ForceFlag},
	Action:       destroyAction,
}

func destroyAction(c *cmd.Context) error {
	if err := cmd.CheckExpectedArgs(c, 1, true); err != nil {
		return err
	}
	hasProtector := protectorFlag.Value != ""
	hasPolicy := policyFlag.Value != ""
	hasMount := len(c.Args) == 1
	if (hasProtector && hasPolicy) || (hasPolicy && hasMount) || (hasMount && hasProtector) {
		return cmd.UsageError(fmt.Sprintf("Multiple of %s, %s, %s provided",
			protectorFlag, policyFlag, usedMountpointArg))
	}

	switch {
	case hasProtector:
		// Case (1) - protector destroy
		protector, err := getProtectorFromFlag(protectorFlag.Value, nil)
		if err != nil {
			return err
		}

		prompt := fmt.Sprintf("Destroy protector %s on %q?",
			protector.Descriptor(), protector.Context.Mount.Path)
		warning := "All files protected only with this protector will be lost!!"
		if err = cmd.AskConfirmation(prompt, warning, false); err != nil {
			return err
		}
		if err = protector.Destroy(); err != nil {
			return err
		}

		fmt.Fprintf(cmd.Output, "Protector %s deleted from filesystem %q.\n",
			protector.Descriptor(), protector.Context.Mount.Path)
		return nil
	case hasPolicy:
		// Case (2) - policy destroy
		policy, err := getPolicyFromFlag(policyFlag.Value, nil)
		if err != nil {
			return err
		}

		prompt := fmt.Sprintf("Destroy policy %s on %q?",
			policy.Descriptor(), policy.Context.Mount.Path)
		warning := "All files and directories using this policy will be lost!"
		if err = cmd.AskConfirmation(prompt, warning, false); err != nil {
			return err
		}
		if err = policy.Destroy(); err != nil {
			return err
		}

		fmt.Fprintf(cmd.Output, "Policy %s deleted from filesystem %q.\n",
			policy.Descriptor(), policy.Context.Mount.Path)
		return nil
	case hasMount:
		// Case (3) - mountpoint destroy
		ctx, err := actions.NewContextFromMountpoint(c.Args[0], nil)
		if err != nil {
			return err
		}

		prompt := fmt.Sprintf("Destroy all the metadata on %q?", ctx.Mount.Path)
		warning := "All the encrypted files on this filesystem will be lost!"
		if err := cmd.AskConfirmation(prompt, warning, false); err != nil {
			return err
		}
		if err := ctx.Mount.RemoveAllMetadata(); err != nil {
			return err
		}

		fmt.Fprintf(cmd.Output, "All metadata on %q deleted.\n", ctx.Mount.Path)
		return nil
	default:
		return cmd.UsageError(fmt.Sprintf("None of %s, %s, %s provided",
			protectorFlag, policyFlag, usedMountpointArg))
	}
}

var changeCommand = &cmd.Command{
	Name:         "change-passphrase",
	Title:        "change the passphrase for a protector",
	UsageLines:   []string{protectorFlag.String()},
	InheritFlags: true,
	Flags:        []cmd.Flag{protectorFlag},
	Action:       changeAction,
}

func changeAction(c *cmd.Context) error {
	if err := cmd.CheckExpectedArgs(c, 0, false); err != nil {
		return err
	}
	if err := cmd.CheckRequiredFlags([]*cmd.StringFlag{protectorFlag}); err != nil {
		return err
	}

	protector, err := getProtectorFromFlag(protectorFlag.Value, nil)
	if err != nil {
		return err
	}
	if err := protector.Unlock(oldExistingKeyFn); err != nil {
		return err
	}
	defer protector.Lock()
	if err := protector.Rewrap(newCreateKeyFn); err != nil {
		return err
	}

	fmt.Fprintf(cmd.Output, "Passphrase for protector %s successfully changed.\n",
		protector.Descriptor())
	return nil
}

var addProtectorCommand = &cmd.Command{
	Name:  "add-protector-to-policy",
	Title: "start protecting a policy with a protector",
	UsageLines: []string{fmt.Sprintf("%s [%s] %s [%s]", protectorFlag,
		keyFileFlag, policyFlag, unlockWithFlag)},
	InheritFlags: true,
	Flags:        []cmd.Flag{keyFileFlag, unlockWithFlag},
	Action:       addProtectorAction,
}

func addProtectorAction(c *cmd.Context) error {
	if err := cmd.CheckExpectedArgs(c, 0, false); err != nil {
		return err
	}
	err := cmd.CheckRequiredFlags([]*cmd.StringFlag{protectorFlag, policyFlag})
	if err != nil {
		return err
	}

	protector, err := getProtectorFromFlag(protectorFlag.Value, nil)
	if err != nil {
		return err
	}
	policy, err := getPolicyFromFlag(policyFlag.Value, protector.Context.TargetUser)
	if err != nil {
		return err
	}
	// Sanity check before unlocking everything
	if err := policy.AddProtector(protector); errors.Cause(err) != actions.ErrLocked {
		return err
	}

	prompt := fmt.Sprintf("Protect policy %s with protector %s?",
		policy.Descriptor(), protector.Descriptor())
	warning := "All files using this policy will be accessible with this protector!"
	if err := cmd.AskConfirmation(prompt, warning, true); err != nil {
		return err
	}

	if err := protector.Unlock(existingKeyFn); err != nil {
		return err
	}
	if err := policy.Unlock(optionFn, existingKeyFn); err != nil {
		return err
	}
	if err := policy.AddProtector(protector); err != nil {
		return err
	}

	fmt.Fprintf(cmd.Output, "Protector %s now protecting policy %s.\n",
		protector.Descriptor(), policy.Descriptor())
	return nil
}

var removeProtectorCommand = &cmd.Command{
	Name:  "remove-protector-from-policy",
	Title: "stop protecting a policy with a protector",
	UsageLines: []string{fmt.Sprintf("%s %s [%s]", protectorFlag,
		policyFlag, cmd.ForceFlag)},
	InheritFlags: true,
	Flags:        []cmd.Flag{keyFileFlag, unlockWithFlag},
	Action:       removeProtectorAction,
}

func removeProtectorAction(c *cmd.Context) error {
	if err := cmd.CheckExpectedArgs(c, 0, false); err != nil {
		return err
	}
	err := cmd.CheckRequiredFlags([]*cmd.StringFlag{protectorFlag, policyFlag})
	if err != nil {
		return err
	}

	// We do not need to unlock anything for this operation
	protector, err := getProtectorFromFlag(protectorFlag.Value, nil)
	if err != nil {
		return err
	}
	policy, err := getPolicyFromFlag(policyFlag.Value, protector.Context.TargetUser)
	if err != nil {
		return err
	}

	prompt := fmt.Sprintf("Stop protecting policy %s with protector %s?",
		policy.Descriptor(), protector.Descriptor())
	warning := "All files using this policy will NOT BE ACCESSIBLE with this protector!"
	if err := cmd.AskConfirmation(prompt, warning, false); err != nil {
		return err
	}
	if err := policy.RemoveProtector(protector); err != nil {
		return err
	}

	fmt.Fprintf(cmd.Output, "Protector %s no longer protecting policy %s.\n",
		protector.Descriptor(), policy.Descriptor())
	return nil
}

var dumpCommand = &cmd.Command{
	Name:       "dump",
	Title:      "display debug info about protectors and policies",
	UsageLines: []string{protectorFlag.String(), policyFlag.String()},
	Flags:      []cmd.Flag{protectorFlag, policyFlag, cmd.VerboseFlag, cmd.HelpFlag},
	Action:     dumpAction,
}

func dumpAction(c *cmd.Context) error {
	if err := cmd.CheckExpectedArgs(c, 0, false); err != nil {
		return err
	}
	hasProtector := protectorFlag.Value != ""
	hasPolicy := policyFlag.Value != ""
	if hasProtector && hasPolicy {
		return cmd.UsageError(fmt.Sprintf("Multiple of %s, %s provided",
			protectorFlag, policyFlag))
	}

	switch {
	case hasProtector:
		// Case (1) - protector dump
		protector, err := getProtectorFromFlag(protectorFlag.Value, nil)
		if err != nil {
			return err
		}
		fmt.Fprintln(cmd.Output, protector)
		return nil
	case hasPolicy:
		// Case (2) - policy dump
		policy, err := getPolicyFromFlag(policyFlag.Value, nil)
		if err != nil {
			return err
		}
		fmt.Fprintln(cmd.Output, policy)
		return nil
	default:
		return cmd.UsageError(fmt.Sprintf("None of %s, %s provided",
			protectorFlag, policyFlag))
	}
}