package catalog

import (
	"context"
	"database/sql"
	"errors"
	"io"
	"log/slog"
	"path/filepath"
	"testing"

	"github.com/mithral/vellum/internal/auth"
	"github.com/mithral/vellum/internal/core"
	"github.com/mithral/vellum/migrations"
)

// testDB builds a migrated database in a temp directory.
func testDB(t *testing.T) *sql.DB {
	t.Helper()
	db, err := core.OpenDB(filepath.Join(t.TempDir(), "catalog.db"))
	if err != nil {
		t.Fatalf("open: %v", err)
	}
	t.Cleanup(func() { _ = db.Close() })
	log := slog.New(slog.NewTextHandler(io.Discard, nil))
	if err := core.Migrate(context.Background(), db, migrations.FS, log); err != nil {
		t.Fatalf("migrate: %v", err)
	}
	return db
}

// newLibrary inserts a library and returns its id.
func newLibrary(t *testing.T, db *sql.DB, name string) int64 {
	t.Helper()
	res, err := db.Exec(
		`INSERT INTO libraries (kind, name, root_path) VALUES ('ebooks', ?, ?)`,
		name, "/media/"+name)
	if err != nil {
		t.Fatalf("insert library: %v", err)
	}
	id, _ := res.LastInsertId()
	return id
}

// newUser inserts a user. isAdmin decides whether grants matter.
func newUser(t *testing.T, db *sql.DB, name string, admin bool) auth.User {
	t.Helper()
	adminFlag := 0
	if admin {
		adminFlag = 1
	}
	res, err := db.Exec(
		`INSERT INTO users (username, display_name, password_hash, is_admin) VALUES (?, ?, 'x', ?)`,
		name, name, adminFlag)
	if err != nil {
		t.Fatalf("insert user: %v", err)
	}
	id, _ := res.LastInsertId()
	return auth.User{ID: id, Username: name, IsAdmin: admin}
}

// newItem inserts an item with one file, including codec facts.
func newItem(t *testing.T, db *sql.DB, libID int64, title string) int64 {
	t.Helper()
	res, err := db.Exec(`
		INSERT INTO media_items (library_id, kind, path, title, sort_title, year)
		VALUES (?, 'ebooks', ?, ?, ?, 1999)`, libID, title+".epub", title, title)
	if err != nil {
		t.Fatalf("insert item: %v", err)
	}
	itemID, _ := res.LastInsertId()
	if _, err := db.Exec(`
		INSERT INTO media_files (item_id, path, size, mtime, container, duration_ms,
		                         vcodec, acodec, width, height)
		VALUES (?, ?, 100, '1700000000000000000', 'mp4', 5000, 'h264', 'aac', 640, 360)`,
		itemID, title+".epub"); err != nil {
		t.Fatalf("insert file: %v", err)
	}
	return itemID
}

func grant(t *testing.T, db *sql.DB, u auth.User, libID int64) {
	t.Helper()
	if _, err := db.Exec(
		`INSERT INTO library_grants (user_id, library_id, can_read) VALUES (?, ?, 1)`,
		u.ID, libID); err != nil {
		t.Fatalf("grant: %v", err)
	}
}

func TestLoadReturnsCodecFacts(t *testing.T) {
	db := testDB(t)
	lib := newLibrary(t, db, "A")
	itemID := newItem(t, db, lib, "Thing")

	it, err := LoadUnchecked(context.Background(), db, itemID)
	if err != nil {
		t.Fatal(err)
	}
	if it.Title != "Thing" || it.LibraryID != lib || it.Kind != "ebooks" {
		t.Errorf("unexpected item: %+v", it)
	}
	if it.RootPath != "/media/A" {
		t.Errorf("RootPath = %q", it.RootPath)
	}
	if it.AbsPath() != "/media/A/Thing.epub" {
		t.Errorf("AbsPath = %q", it.AbsPath())
	}
	if it.ModTime.IsZero() {
		t.Error("ModTime not parsed from the file's mtime")
	}

	files, err := Files(context.Background(), db, itemID)
	if err != nil {
		t.Fatal(err)
	}
	if len(files) != 1 {
		t.Fatalf("files = %d, want 1", len(files))
	}
	f := files[0]
	if f.VCodec != "h264" || f.ACodec != "aac" || f.Width != 640 || f.DurationMS != 5000 {
		t.Errorf("codec facts lost: %+v", f)
	}
	if f.Missing {
		t.Error("a present file reported as missing")
	}
}

// The security property: a missing item and a forbidden item must be
// INDISTINGUISHABLE, or a 403 would leak the existence of another user's
// library.
func TestLoadForForbiddenIsIndistinguishableFromAbsent(t *testing.T) {
	db := testDB(t)
	ctx := context.Background()
	lib := newLibrary(t, db, "Secret")
	itemID := newItem(t, db, lib, "Hidden")

	outsider := newUser(t, db, "outsider", false)
	granted := newUser(t, db, "granted", false)
	grant(t, db, granted, lib)

	// Forbidden: the item exists but this user has no grant.
	_, errForbidden := LoadFor(ctx, db, outsider, itemID)
	// Absent: no such row at all.
	_, errAbsent := LoadFor(ctx, db, outsider, itemID+9999)

	if !errors.Is(errForbidden, ErrNotFound) {
		t.Errorf("forbidden error = %v, want ErrNotFound", errForbidden)
	}
	if !errors.Is(errAbsent, ErrNotFound) {
		t.Errorf("absent error = %v, want ErrNotFound", errAbsent)
	}
	if errForbidden.Error() != errAbsent.Error() {
		t.Errorf("errors differ and would leak existence: %q vs %q",
			errForbidden, errAbsent)
	}

	// Positive control: a granted user does get it.
	if _, err := LoadFor(ctx, db, granted, itemID); err != nil {
		t.Errorf("granted user denied: %v", err)
	}
}

func TestAdminBypassesGrants(t *testing.T) {
	db := testDB(t)
	ctx := context.Background()
	lib := newLibrary(t, db, "Any")
	itemID := newItem(t, db, lib, "Thing")

	admin := newUser(t, db, "root", true)
	if _, err := LoadFor(ctx, db, admin, itemID); err != nil {
		t.Errorf("admin denied: %v", err)
	}
}

func TestFileByIDIsScopedToItsItem(t *testing.T) {
	db := testDB(t)
	ctx := context.Background()
	lib := newLibrary(t, db, "A")
	first := newItem(t, db, lib, "One")
	second := newItem(t, db, lib, "Two")

	other, err := FirstFile(ctx, db, second)
	if err != nil {
		t.Fatal(err)
	}

	// Asking for item Two's file through item One must not resolve.
	if _, err := FileByID(ctx, db, first, other.ID); !errors.Is(err, ErrNotFound) {
		t.Errorf("file id leaked across items: err = %v, want ErrNotFound", err)
	}
	if _, err := FileByID(ctx, db, second, other.ID); err != nil {
		t.Errorf("legitimate lookup failed: %v", err)
	}
}

func TestFilesForRespectsGrants(t *testing.T) {
	db := testDB(t)
	ctx := context.Background()
	lib := newLibrary(t, db, "A")
	itemID := newItem(t, db, lib, "Thing")

	outsider := newUser(t, db, "outsider", false)
	if _, err := FilesFor(ctx, db, outsider, itemID); !errors.Is(err, ErrNotFound) {
		t.Errorf("FilesFor leaked to an ungranted user: %v", err)
	}
}

func TestFileCount(t *testing.T) {
	db := testDB(t)
	lib := newLibrary(t, db, "A")
	itemID := newItem(t, db, lib, "Thing")

	n, err := FileCount(context.Background(), db, itemID)
	if err != nil {
		t.Fatal(err)
	}
	if n != 1 {
		t.Errorf("FileCount = %d, want 1", n)
	}
}