package fake

import (
	"bytes"
	"context"
	"errors"
	"io"
	"reflect"
	"testing"

	"gitea.maximumdirect.net/eric/distributor/internal/storage"
)

func TestBackendReadWriteAndStream(t *testing.T) {
	backend := New()
	entry, err := backend.WriteFile(context.Background(), "reports/report.md", []byte("hello"), storage.WriteOptions{})
	if err != nil {
		t.Fatalf("WriteFile() error = %v", err)
	}
	if entry.Path != "reports/report.md" || entry.Type != storage.EntryTypeFile || entry.Size != 5 {
		t.Fatalf("entry = %#v, want file metadata", entry)
	}

	data, err := backend.ReadFile(context.Background(), "reports/report.md")
	if err != nil {
		t.Fatalf("ReadFile() error = %v", err)
	}
	reader, err := backend.OpenReader(context.Background(), "reports/report.md")
	if err != nil {
		t.Fatalf("OpenReader() error = %v", err)
	}
	streamed, err := io.ReadAll(reader)
	closeErr := reader.Close()
	if err != nil || closeErr != nil {
		t.Fatalf("stream read error = %v close = %v", err, closeErr)
	}
	if !bytes.Equal(data, streamed) {
		t.Fatalf("streamed = %q, want %q", streamed, data)
	}

	_, err = backend.WriteFile(context.Background(), "reports/report.md", []byte("again"), storage.WriteOptions{})
	if !storage.IsAlreadyExists(err) {
		t.Fatalf("WriteFile existing error = %v, want already exists", err)
	}
}

func TestBackendStatWalkAndList(t *testing.T) {
	backend := New()
	mustWrite(t, backend, "b/two.txt", "2")
	mustWrite(t, backend, "a/one.txt", "1")

	entry, err := backend.Stat(context.Background(), "a")
	if err != nil {
		t.Fatalf("Stat directory error = %v", err)
	}
	if entry.Type != storage.EntryTypeDirectory {
		t.Fatalf("entry type = %s, want directory", entry.Type)
	}

	entries, err := storage.List(context.Background(), backend, "", storage.WalkOptions{Recursive: true})
	if err != nil {
		t.Fatalf("List() error = %v", err)
	}
	var paths []string
	for _, entry := range entries {
		paths = append(paths, entry.Path)
	}
	want := []string{"a", "a/one.txt", "b", "b/two.txt"}
	if !reflect.DeepEqual(paths, want) {
		t.Fatalf("paths = %v, want %v", paths, want)
	}
}

func TestBackendRejectsInvalidPaths(t *testing.T) {
	backend := New()
	_, err := backend.WriteFile(context.Background(), "../outside", []byte("data"), storage.WriteOptions{})
	if !storage.IsInvalidPath(err) {
		t.Fatalf("WriteFile traversal error = %v, want invalid path", err)
	}
	_, err = backend.ReadFile(context.Background(), `bad\path`)
	if !storage.IsInvalidPath(err) {
		t.Fatalf("ReadFile backslash error = %v, want invalid path", err)
	}
}

func TestBackendSymlinkReportingAndReadRejection(t *testing.T) {
	backend := New()
	if err := backend.AddSymlink("link.txt"); err != nil {
		t.Fatalf("AddSymlink() error = %v", err)
	}
	entry, err := backend.Stat(context.Background(), "link.txt")
	if err != nil {
		t.Fatalf("Stat() error = %v", err)
	}
	if entry.Type != storage.EntryTypeSymlink {
		t.Fatalf("entry type = %s, want symlink", entry.Type)
	}
	_, err = backend.ReadFile(context.Background(), "link.txt")
	if !storage.IsUnsupported(err) {
		t.Fatalf("ReadFile symlink error = %v, want unsupported", err)
	}
}

func TestBackendWriteFromSizeMismatch(t *testing.T) {
	backend := New()
	_, err := backend.WriteFrom(context.Background(), "out.txt", bytes.NewBufferString("short"), storage.WriteOptions{SizeKnown: true, Size: 99})
	if !storage.IsConflict(err) {
		t.Fatalf("WriteFrom size mismatch error = %v, want conflict", err)
	}
	if _, err := backend.Stat(context.Background(), "out.txt"); !storage.IsNotFound(err) {
		t.Fatalf("Stat after failed write error = %v, want not found", err)
	}
}

func TestBackendManagedDeletion(t *testing.T) {
	backend := New()
	mustWrite(t, backend, "bundle/report.html", "html")
	mustWrite(t, backend, "bundle/keep.txt", "keep")
	statePath, err := storage.StatePath("bundle")
	if err != nil {
		t.Fatalf("StatePath() error = %v", err)
	}
	mustWrite(t, backend, statePath, "{}")

	err = backend.DeleteManagedBundle(context.Background(), "bundle", []string{"report.html"}, storage.DeleteOptions{PruneEmptyDirs: true})
	if err != nil {
		t.Fatalf("DeleteManagedBundle() error = %v", err)
	}
	if _, err := backend.Stat(context.Background(), "bundle/report.html"); !storage.IsNotFound(err) {
		t.Fatalf("managed output stat error = %v, want not found", err)
	}
	if _, err := backend.Stat(context.Background(), statePath); !storage.IsNotFound(err) {
		t.Fatalf("state stat error = %v, want not found", err)
	}
	if _, err := backend.Stat(context.Background(), "bundle/keep.txt"); err != nil {
		t.Fatalf("unlisted file stat error = %v", err)
	}
	if err := backend.DeleteManagedBundle(context.Background(), "bundle", []string{""}, storage.DeleteOptions{}); !storage.IsInvalidPath(err) {
		t.Fatalf("DeleteManagedBundle invalid output error = %v, want invalid path", err)
	}
}

func TestBackendDeletePrefixStaysWithinPrefix(t *testing.T) {
	backend := New()
	mustWrite(t, backend, "bundle/report.md", "report")
	mustWrite(t, backend, "bundle/nested/old.txt", "old")
	mustWrite(t, backend, "bundle-sibling/keep.txt", "keep")
	mustWrite(t, backend, "outside.txt", "outside")

	if err := backend.DeletePrefix(context.Background(), "bundle", storage.DeleteOptions{IgnoreMissing: true, PruneEmptyDirs: true}); err != nil {
		t.Fatalf("DeletePrefix() error = %v", err)
	}
	if _, err := backend.Stat(context.Background(), "bundle/report.md"); !storage.IsNotFound(err) {
		t.Fatalf("deleted file stat error = %v, want not found", err)
	}
	if _, err := backend.Stat(context.Background(), "bundle/nested/old.txt"); !storage.IsNotFound(err) {
		t.Fatalf("deleted nested file stat error = %v, want not found", err)
	}
	if _, err := backend.Stat(context.Background(), "bundle-sibling/keep.txt"); err != nil {
		t.Fatalf("sibling stat error = %v", err)
	}
	if _, err := backend.Stat(context.Background(), "outside.txt"); err != nil {
		t.Fatalf("outside stat error = %v", err)
	}
}

func TestBackendHasAnyAndWalkStop(t *testing.T) {
	backend := New()
	found, err := backend.HasAny(context.Background(), "missing")
	if err != nil {
		t.Fatalf("HasAny missing error = %v", err)
	}
	if found {
		t.Fatal("HasAny missing = true, want false")
	}
	mustWrite(t, backend, "bundle/report.md", "report")
	found, err = backend.HasAny(context.Background(), "bundle")
	if err != nil {
		t.Fatalf("HasAny bundle error = %v", err)
	}
	if !found {
		t.Fatal("HasAny bundle = false, want true")
	}
	found, err = backend.HasAny(context.Background(), "bund")
	if err != nil {
		t.Fatalf("HasAny sibling prefix error = %v", err)
	}
	if found {
		t.Fatal("HasAny sibling prefix = true, want false")
	}

	visited := 0
	err = backend.Walk(context.Background(), "", storage.WalkOptions{Recursive: true}, func(storage.Entry) error {
		visited++
		return storage.ErrStopWalk
	})
	if err != nil {
		t.Fatalf("Walk stop error = %v", err)
	}
	if visited != 1 {
		t.Fatalf("visited = %d, want 1", visited)
	}

	errSentinel := errors.New("callback")
	err = backend.Walk(context.Background(), "", storage.WalkOptions{Recursive: true}, func(storage.Entry) error {
		return errSentinel
	})
	if !errors.Is(err, errSentinel) {
		t.Fatalf("Walk callback error = %v, want sentinel", err)
	}
}

func mustWrite(t *testing.T, backend *Backend, path, data string) {
	t.Helper()
	if _, err := backend.WriteFile(context.Background(), path, []byte(data), storage.WriteOptions{}); err != nil {
		t.Fatalf("WriteFile(%q) error = %v", path, err)
	}
}