//go:build !windows
// +build !windows

/*
   Copyright The containerd Authors.

   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.
*/

package continuity

import (
	"bytes"
	_ "crypto/sha256"
	"errors"
	"fmt"
	"math/rand"
	"os"
	"path/filepath"
	"sort"
	"syscall"
	"testing"

	"github.com/containerd/continuity/devices"
	"github.com/opencontainers/go-digest"
)

// Hard things:
//  1. Groups/gid - no standard library support.
//  2. xattrs - must choose package to provide this.
//  3. ADS - no clue where to start.

func TestWalkFS(t *testing.T) {

	// Testing:
	// 1. Setup different files:
	//		- links
	//			- sibling directory - relative
	//			- sibling directory - absolute
	//			- parent directory - absolute
	//			- parent directory - relative
	//		- illegal links
	//			- parent directory - relative, out of root
	//			- parent directory - absolute, out of root
	//		- regular files
	//		- character devices
	//		- what about sticky bits?
	// 2. Build the manifest.
	// 3. Verify expected result.
	testResources := []dresource{
		{
			path: "a",
			mode: 0o644,
		},
		{
			kind:   rhardlink,
			path:   "a-hardlink",
			target: "a",
		},
		{
			kind: rdirectory,
			path: "b",
			mode: 0o755,
		},
		{
			kind:   rhardlink,
			path:   "b/a-hardlink",
			target: "a",
		},
		{
			path: "b/a",
			mode: 0o600 | os.ModeSticky,
		},
		{
			kind: rdirectory,
			path: "c",
			mode: 0o755,
		},
		{
			path: "c/a",
			mode: 0o644,
		},
		{
			kind:   rrelsymlink,
			path:   "c/ca-relsymlink",
			mode:   0o600,
			target: "a",
		},
		{
			kind:   rrelsymlink,
			path:   "c/a-relsymlink",
			mode:   0o600,
			target: "../a",
		},
		{
			kind:   rabssymlink,
			path:   "c/a-abssymlink",
			mode:   0o600,
			target: "a",
		},
		// TODO(stevvooe): Make sure we can test this case and get proper
		// errors when it is encountered.
		// {
		// 	// create a bad symlink and make sure we don't include it.
		// 	kind:   relsymlink,
		// 	path:   "c/a-badsymlink",
		// 	mode:   0600,
		// 	target: "../../..",
		// },

		// TODO(stevvooe): Must add tests for xattrs, with symlinks,
		// directories and regular files.

		{
			kind: rnamedpipe,
			path: "fifo",
			mode: 0o666 | os.ModeNamedPipe,
		},

		{
			kind: rdirectory,
			path: "/dev",
			mode: 0o755,
		},

		// NOTE(stevvooe): Below here, we add a few simple character devices.
		// Block devices are untested but should be nearly the same as
		// character devices.
		// devNullResource,
		// devZeroResource,
	}

	root := t.TempDir()
	generateTestFiles(t, root, testResources)

	ctx, err := NewContext(root)
	if err != nil {
		t.Fatalf("error getting context: %v", err)
	}

	m, err := BuildManifest(ctx)
	if err != nil {
		t.Fatalf("error building manifest: %v", err)
	}

	var b bytes.Buffer
	MarshalText(&b, m)
	t.Log(b.String())

	// TODO(dmcgowan): always verify, currently hard links not supported
	//if err := VerifyManifest(ctx, m); err != nil {
	//	t.Fatalf("error verifying manifest: %v")
	//}

	expectedResources, err := expectedResourceList(root, testResources)
	if err != nil {
		// TODO(dmcgowan): update function to panic, this would mean test setup error
		t.Fatalf("error creating resource list: %v", err)
	}

	// Diff resources
	diff := diffResourceList(expectedResources, m.Resources)
	if diff.HasDiff() {
		t.Log("Resource list difference")
		for _, a := range diff.Additions {
			t.Logf("Unexpected resource: %#v", a)
		}
		for _, d := range diff.Deletions {
			t.Logf("Missing resource: %#v", d)
		}
		for _, u := range diff.Updates {
			t.Logf("Changed resource:\n\tExpected: %#v\n\tActual:   %#v", u.Original, u.Updated)
		}

		t.FailNow()
	}
}

// TODO(stevvooe): At this time, we have a nice testing framework to define
// and build resources. This will likely be a pre-cursor to the packages
// public interface.
type kind int

func (k kind) String() string {
	switch k {
	case rfile:
		return "file"
	case rdirectory:
		return "directory"
	case rhardlink:
		return "hardlink"
	case rchardev:
		return "chardev"
	case rnamedpipe:
		return "namedpipe"
	}

	panic(fmt.Sprintf("unknown kind: %v", int(k)))
}

const (
	rfile kind = iota
	rdirectory
	rhardlink
	rrelsymlink
	rabssymlink
	rchardev
	rnamedpipe
)

var (
	rng = rand.New(rand.NewSource(1))
)

type dresource struct {
	kind         kind
	path         string
	mode         os.FileMode
	target       string // hard/soft link target
	digest       digest.Digest
	size         int
	uid          int64
	gid          int64
	major, minor int
}

func generateTestFiles(t *testing.T, root string, resources []dresource) {
	for i, resource := range resources {
		p := filepath.Join(root, resource.path)
		switch resource.kind {
		case rfile:
			size := rng.Intn(4 << 20)
			d := make([]byte, size)
			randomBytes(d)
			dgst := digest.FromBytes(d)
			resources[i].digest = dgst
			resources[i].size = size

			// this relies on the proper directory parent being defined.
			if err := os.WriteFile(p, d, resource.mode); err != nil {
				t.Fatalf("error writing %q: %v", p, err)
			}
		case rdirectory:
			if err := os.Mkdir(p, resource.mode); err != nil {
				t.Fatalf("error creating directory %q: %v", p, err)
			}
		case rhardlink:
			target := filepath.Join(root, resource.target)
			if err := os.Link(target, p); err != nil {
				t.Fatalf("error creating hardlink: %v", err)
			}
		case rrelsymlink:
			if err := os.Symlink(resource.target, p); err != nil {
				t.Fatalf("error creating symlink: %v", err)
			}
		case rabssymlink:
			// for absolute links, we join with root.
			target := filepath.Join(root, resource.target)

			if err := os.Symlink(target, p); err != nil {
				t.Fatalf("error creating symlink: %v", err)
			}
		case rchardev, rnamedpipe:
			if err := devices.Mknod(p, resource.mode, resource.major, resource.minor); err != nil {
				t.Fatalf("error creating device %q: %v", p, err)
			}
		default:
			t.Fatalf("unknown resource type: %v", resource.kind)
		}

		st, err := os.Lstat(p)
		if err != nil {
			t.Fatalf("error statting after creation: %v", err)
		}
		resources[i].uid = int64(st.Sys().(*syscall.Stat_t).Uid)
		resources[i].gid = int64(st.Sys().(*syscall.Stat_t).Gid)
		resources[i].mode = st.Mode()

		// TODO: Readback and join xattr
	}

	// log the test root for future debugging
	if err := filepath.Walk(root, func(p string, fi os.FileInfo, err error) error {
		if fi.Mode()&os.ModeSymlink != 0 {
			target, err := os.Readlink(p)
			if err != nil {
				return err
			}
			t.Log(fi.Mode(), p, "->", target)
		} else {
			t.Log(fi.Mode(), p)
		}

		return nil
	}); err != nil {
		t.Fatalf("error walking created root: %v", err)
	}

	var b bytes.Buffer
	if err := tree(&b, root); err != nil {
		t.Fatalf("error running tree: %v", err)
	}
	t.Logf("\n%s", b.String())
}

func randomBytes(p []byte) {
	for i := range p {
		p[i] = byte(rng.Intn(1<<8 - 1))
	}
}

// expectedResourceList sorts the set of resources into the order
// expected in the manifest and collapses hardlinks
func expectedResourceList(root string, resources []dresource) ([]Resource, error) {
	resourceMap := map[string]Resource{}
	paths := []string{}
	for _, r := range resources {
		absPath := r.path
		if !filepath.IsAbs(absPath) {
			absPath = "/" + absPath
		}
		switch r.kind {
		case rfile:
			f := &regularFile{
				resource: resource{
					paths: []string{absPath},
					mode:  r.mode,
					uid:   r.uid,
					gid:   r.gid,
				},
				size:    int64(r.size),
				digests: []digest.Digest{r.digest},
			}
			resourceMap[absPath] = f
			paths = append(paths, absPath)
		case rdirectory:
			d := &directory{
				resource: resource{
					paths: []string{absPath},
					mode:  r.mode,
					uid:   r.uid,
					gid:   r.gid,
				},
			}
			resourceMap[absPath] = d
			paths = append(paths, absPath)
		case rhardlink:
			targetPath := r.target
			if !filepath.IsAbs(targetPath) {
				targetPath = "/" + targetPath
			}
			target, ok := resourceMap[targetPath]
			if !ok {
				return nil, errors.New("must specify target before hardlink for test resources")
			}
			rf, ok := target.(*regularFile)
			if !ok {
				return nil, errors.New("hardlink target must be regular file")
			}
			// TODO(dmcgowan): full merge
			rf.paths = append(rf.paths, absPath)
			// TODO(dmcgowan): check if first path is now different, changes source order and should update
			// resource map key, to avoid canonically ordered first should be regular file
			sort.Stable(sort.StringSlice(rf.paths))
		case rrelsymlink, rabssymlink:
			targetPath := r.target
			if r.kind == rabssymlink && !filepath.IsAbs(r.target) {
				// for absolute links, we join with root.
				targetPath = filepath.Join(root, targetPath)
			}
			s := &symLink{
				resource: resource{
					paths: []string{absPath},
					mode:  r.mode,
					uid:   r.uid,
					gid:   r.gid,
				},
				target: targetPath,
			}
			resourceMap[absPath] = s
			paths = append(paths, absPath)
		case rchardev:
			d := &device{
				resource: resource{
					paths: []string{absPath},
					mode:  r.mode,
					uid:   r.uid,
					gid:   r.gid,
				},
				major: uint64(r.major),
				minor: uint64(r.minor),
			}
			resourceMap[absPath] = d
			paths = append(paths, absPath)
		case rnamedpipe:
			p := &namedPipe{
				resource: resource{
					paths: []string{absPath},
					mode:  r.mode,
					uid:   r.uid,
					gid:   r.gid,
				},
			}
			resourceMap[absPath] = p
			paths = append(paths, absPath)
		default:
			return nil, fmt.Errorf("unknown resource type: %v", r.kind)
		}
	}

	if len(resourceMap) < len(paths) {
		return nil, errors.New("resource list has duplicated paths")
	}

	sort.Strings(paths)

	manifestResources := make([]Resource, len(paths))
	for i, p := range paths {
		manifestResources[i] = resourceMap[p]
	}

	return manifestResources, nil
}
