package engine

import (
	"errors"
	"io/fs"
	"os"
	"path/filepath"
	"testing"
	"testing/fstest"
)

type trackedHostRoot struct {
	root     *os.Root
	closed   *int
	failOpen bool
}

func (r *trackedHostRoot) Open(name string) (*os.File, error) {
	if r.failOpen {
		return nil, fs.ErrPermission
	}
	return r.root.Open(name)
}
func (r *trackedHostRoot) Close() error {
	(*r.closed)++
	return r.root.Close()
}

func TestRootedHostFSClosesRootOnSuccessfulAndFailedOpen(t *testing.T) {
	rootPath := t.TempDir()
	if err := os.WriteFile(filepath.Join(rootPath, "resource.txt"), []byte("resource"), 0o600); err != nil {
		t.Fatal(err)
	}
	opened, closed := 0, 0
	failOpen := false
	filesystem := rootedHostFS{root: rootPath, openRoot: func(name string) (hostResourceRoot, error) {
		root, err := os.OpenRoot(name)
		if err != nil {
			return nil, err
		}
		opened++
		return &trackedHostRoot{root: root, closed: &closed, failOpen: failOpen}, nil
	}}
	if _, err := filesystem.Open("../resource.txt"); !errors.Is(err, fs.ErrInvalid) || opened != 0 {
		t.Fatalf("invalid path = %v; roots opened %d", err, opened)
	}
	if _, err := filesystem.Open("missing.txt"); !errors.Is(err, fs.ErrNotExist) || opened != 1 || closed != 1 {
		t.Fatalf("missing resource = %v; opened %d, closed %d", err, opened, closed)
	}
	failOpen = true
	if _, err := filesystem.Open("resource.txt"); !errors.Is(err, fs.ErrPermission) || opened != 2 || closed != 2 {
		t.Fatalf("failed inner open = %v; opened %d, closed %d", err, opened, closed)
	}
	failOpen = false
	file, err := filesystem.Open("resource.txt")
	if err != nil || opened != 3 || closed != 2 {
		t.Fatalf("resource open = %v; opened %d, closed %d", err, opened, closed)
	}
	if err := file.Close(); err != nil || closed != 3 {
		t.Fatalf("resource close = %v; opened %d, closed %d", err, opened, closed)
	}
	if _, err := file.Read(make([]byte, 1)); err == nil {
		t.Fatal("closed resource file remained readable")
	}
	directory, err := filesystem.Open(".")
	if err != nil {
		t.Fatal(err)
	}
	reader, ok := directory.(fs.ReadDirFile)
	if !ok {
		t.Fatal("rooted host directory did not expose ReadDirFile")
	}
	entries, err := reader.ReadDir(-1)
	if err != nil || len(entries) != 1 || entries[0].Name() != "resource.txt" {
		t.Fatalf("directory entries = %#v, %v", entries, err)
	}
	if err := directory.Close(); err != nil || opened != 4 || closed != 4 {
		t.Fatalf("directory close = %v; opened %d, closed %d", err, opened, closed)
	}
}

func TestNativeResourceViewIsBorrowedAndRooted(t *testing.T) {
	filesystem := &observedFilesystem{files: fstest.MapFS{
		"bundle/config/resource.txt": &fstest.MapFile{Data: []byte("content")},
	}}
	view := rootedNativeFS{filesystem: filesystem, root: "bundle"}
	if filesystem.opened != 0 {
		t.Fatal("constructing a native resource view opened files")
	}
	data, err := fs.ReadFile(view, "config/resource.txt")
	if err != nil || string(data) != "content" {
		t.Fatalf("resource = %q, %v", data, err)
	}
	filesystem.assertClosed(t)
	if _, err := fs.ReadFile(view, "../outside.txt"); !errors.Is(err, fs.ErrInvalid) {
		t.Fatalf("resource escape = %v", err)
	}
}

func TestLoadingClosesNativeFilesAcrossPipelineOutcomes(t *testing.T) {
	type config struct {
		Value   string `yaml:"value"`
		Version string `yaml:"version"`
	}
	for _, test := range []struct {
		name     string
		main     string
		child    string
		failRead string
		options  Options[config]
		wantErr  bool
	}{
		{name: "success", main: "value: retained\n"},
		{name: "acquisition", main: "value: retained\n", failRead: "main.yml", wantErr: true},
		{name: "parse", main: "value: [broken\n", wantErr: true},
		{name: "composition", main: "configkit: {imports: [{path: child.yml}]}\nvalue: first\n", child: "value: second\n", options: Options[config]{Imports: true}, wantErr: true},
		{name: "version", main: "version: wrong\n", options: Options[config]{Definition: Definition[config]{Version: &VersionRule{Path: Keys("version"), Check: func(Version, *Validation) error { return fs.ErrInvalid }}}}, wantErr: true},
		{name: "validation", main: "value: retained\n", options: Options[config]{Definition: Definition[config]{Validate: func(_ *config, validation *Validation) { validation.Error(Keys("value"), "rejected") }}}, wantErr: true},
	} {
		t.Run(test.name, func(t *testing.T) {
			files := fstest.MapFS{"main.yml": &fstest.MapFile{Data: []byte(test.main)}}
			if test.child != "" {
				files["child.yml"] = &fstest.MapFile{Data: []byte(test.child)}
			}
			filesystem := &observedFilesystem{files: files, failRead: test.failRead}
			_, err := testLoad(filesystemFile(newNativeNamespace("bundle", filesystem), "main.yml"), test.options)
			if (err != nil) != test.wantErr {
				t.Fatalf("load error = %v, want failure %v", err, test.wantErr)
			}
			filesystem.assertClosed(t)
		})
	}
}