package library

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

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

func testDB(t *testing.T) *sql.DB {
	t.Helper()
	db, err := core.OpenDB(filepath.Join(t.TempDir(), "lib.db"))
	if err != nil {
		t.Fatalf("OpenDB: %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
}

func testLogger() *slog.Logger {
	return slog.New(slog.NewTextHandler(io.Discard, nil))
}

func writeFile(t *testing.T, path, content string) {
	t.Helper()
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
		t.Fatal(err)
	}
}

func TestRegistryBasics(t *testing.T) {
	if err := ValidateKind("ebooks"); err != nil {
		t.Errorf("ebooks should be valid: %v", err)
	}
	if err := ValidateKind("nonsense"); !errors.Is(err, ErrUnknownKind) {
		t.Errorf("nonsense kind error = %v, want ErrUnknownKind", err)
	}
	if k, ok := KindForExtension(".epub"); !ok || k != "ebooks" {
		t.Errorf("KindForExtension(.epub) = %q,%v", k, ok)
	}
	if k, ok := KindForExtension("CBZ"); !ok || k != "comics" {
		t.Errorf("KindForExtension(CBZ) = %q,%v (should be case-insensitive)", k, ok)
	}
	if len(SupportedTypes()) == 0 {
		t.Error("no media types registered")
	}
}

func TestCleanTitle(t *testing.T) {
	cases := map[string]string{
		"Project Hail Mary.epub":  "Project Hail Mary",
		"the_hobbit.mobi":         "the hobbit",
		"Book.Title.2020.epub":    "Book Title 2020",
		"/deep/path/Saga 001.cbz": "Saga 001",
	}
	for in, want := range cases {
		if got := CleanTitle(in); got != want {
			t.Errorf("CleanTitle(%q) = %q, want %q", in, got, want)
		}
	}
}

func TestCreateLibraryValidation(t *testing.T) {
	db := testDB(t)
	ctx := context.Background()
	root := t.TempDir()

	if _, err := Create(ctx, db, "Good", "ebooks", root); err != nil {
		t.Fatalf("valid create failed: %v", err)
	}
	if _, err := Create(ctx, db, "Good", "ebooks", root); !errors.Is(err, ErrNameExists) {
		t.Errorf("duplicate name error = %v, want ErrNameExists", err)
	}
	if _, err := Create(ctx, db, "Bad", "nonsense", root); !errors.Is(err, ErrUnknownKind) {
		t.Errorf("bad kind error = %v, want ErrUnknownKind", err)
	}
	if _, err := Create(ctx, db, "Bad", "ebooks", "/nope/not/here"); !errors.Is(err, ErrInvalidRoot) {
		t.Errorf("bad root error = %v, want ErrInvalidRoot", err)
	}
}

func TestListVisibleNeverMeansAll(t *testing.T) {
	db := testDB(t)
	ctx := context.Background()
	root := t.TempDir()
	if _, err := Create(ctx, db, "Ebooks", "ebooks", root); err != nil {
		t.Fatal(err)
	}

	libs, err := ListVisible(ctx, db, nil)
	if err != nil {
		t.Fatal(err)
	}
	if len(libs) != 0 {
		t.Errorf("ListVisible(nil) returned %d libraries; empty set must mean none", len(libs))
	}
}

func TestMissingSinceLifecycle(t *testing.T) {
	db := testDB(t)
	ctx := context.Background()
	root := t.TempDir()
	writeFile(t, filepath.Join(root, "a.epub"), "aaaaaaaaaa")
	writeFile(t, filepath.Join(root, "b.epub"), "bbbbbbbbbbbbbbbbbbbb")

	lib, err := Create(ctx, db, "Ebooks", "ebooks", root)
	if err != nil {
		t.Fatalf("Create: %v", err)
	}
	if _, err := Scan(ctx, db, lib, testLogger()); err != nil {
		t.Fatalf("first Scan: %v", err)
	}

	// A present file has no missing timestamp.
	var since string
	if err := db.QueryRowContext(ctx,
		`SELECT missing_since FROM media_files WHERE path = ?`, "b.epub").Scan(&since); err != nil {
		t.Fatal(err)
	}
	if since != "" {
		t.Errorf("present file missing_since = %q, want empty", since)
	}

	// Delete b.epub: it goes missing and the timestamp is recorded.
	if err := os.Remove(filepath.Join(root, "b.epub")); err != nil {
		t.Fatal(err)
	}
	if _, err := Scan(ctx, db, lib, testLogger()); err != nil {
		t.Fatalf("missing Scan: %v", err)
	}
	if err := db.QueryRowContext(ctx,
		`SELECT missing_since FROM media_files WHERE path = ?`, "b.epub").Scan(&since); err != nil {
		t.Fatal(err)
	}
	if since == "" {
		t.Fatal("missing_since was not set on the transition into missing")
	}
	first := since

	// A rescan must not refresh the age.
	if _, err := Scan(ctx, db, lib, testLogger()); err != nil {
		t.Fatalf("rescan: %v", err)
	}
	if err := db.QueryRowContext(ctx,
		`SELECT missing_since FROM media_files WHERE path = ?`, "b.epub").Scan(&since); err != nil {
		t.Fatal(err)
	}
	if since != first {
		t.Errorf("missing_since reset on rescan: %q -> %q", first, since)
	}

	// ListMissing surfaces the file with its age.
	entries, err := ListMissing(ctx, db, []int64{lib.ID})
	if err != nil {
		t.Fatalf("ListMissing: %v", err)
	}
	if len(entries) != 1 {
		t.Fatalf("ListMissing returned %d entries, want 1", len(entries))
	}
	e := entries[0]
	if e.Title != "b" || e.Path != "b.epub" || e.Kind != "ebooks" || e.LibraryID != lib.ID {
		t.Errorf("unexpected missing entry: %+v", e)
	}
	if e.MissingSince != first {
		t.Errorf("entry missing_since = %q, want %q", e.MissingSince, first)
	}

	// Restore the file: missing_since must be cleared, not left behind.
	writeFile(t, filepath.Join(root, "b.epub"), "bbbbbbbbbbbbbbbbbbbb")
	if _, err := Scan(ctx, db, lib, testLogger()); err != nil {
		t.Fatalf("restore Scan: %v", err)
	}
	if err := db.QueryRowContext(ctx,
		`SELECT missing_since FROM media_files WHERE path = ?`, "b.epub").Scan(&since); err != nil {
		t.Fatal(err)
	}
	if since != "" {
		t.Errorf("missing_since after restore = %q, want empty", since)
	}
	if got, _ := ListMissing(ctx, db, []int64{lib.ID}); len(got) != 0 {
		t.Errorf("ListMissing after restore returned %d entries, want 0", len(got))
	}
}

func TestPurgeMissingOnlyDeletesMissingItems(t *testing.T) {
	db := testDB(t)
	ctx := context.Background()
	root := t.TempDir()

	// Two audiobooks, each a folder of tracks.
	writeFile(t, filepath.Join(root, "Book A", "01.mp3"), "a1")
	writeFile(t, filepath.Join(root, "Book A", "02.mp3"), "a2")
	writeFile(t, filepath.Join(root, "Book B", "01.mp3"), "b1")
	writeFile(t, filepath.Join(root, "Book B", "02.mp3"), "b2")

	lib, err := Create(ctx, db, "Audiobooks", "audiobooks", root)
	if err != nil {
		t.Fatalf("Create: %v", err)
	}
	if _, err := Scan(ctx, db, lib, testLogger()); err != nil {
		t.Fatalf("Scan: %v", err)
	}

	// A second library with its own missing item, to prove purge is scoped.
	otherRoot := t.TempDir()
	writeFile(t, filepath.Join(otherRoot, "gone.epub"), "x")
	other, err := Create(ctx, db, "Other", "ebooks", otherRoot)
	if err != nil {
		t.Fatalf("Create other: %v", err)
	}
	if _, err := Scan(ctx, db, other, testLogger()); err != nil {
		t.Fatalf("Scan other: %v", err)
	}
	if err := os.Remove(filepath.Join(otherRoot, "gone.epub")); err != nil {
		t.Fatal(err)
	}
	if _, err := Scan(ctx, db, other, testLogger()); err != nil {
		t.Fatalf("Scan other (missing): %v", err)
	}

	// Remove one track from Book A: the item is not missing, only that file.
	// Remove Book B entirely: the item and both its files are missing.
	if err := os.Remove(filepath.Join(root, "Book A", "02.mp3")); err != nil {
		t.Fatal(err)
	}
	if err := os.RemoveAll(filepath.Join(root, "Book B")); err != nil {
		t.Fatal(err)
	}
	if _, err := Scan(ctx, db, lib, testLogger()); err != nil {
		t.Fatalf("second Scan: %v", err)
	}

	entries, err := ListMissing(ctx, db, []int64{lib.ID})
	if err != nil {
		t.Fatalf("ListMissing: %v", err)
	}
	if len(entries) != 3 {
		t.Fatalf("ListMissing returned %d entries, want 3 (Book A/02 + Book B/01 + Book B/02)", len(entries))
	}

	// Purge must remove only Book B.
	n, err := PurgeMissing(ctx, db, lib.ID)
	if err != nil {
		t.Fatalf("PurgeMissing: %v", err)
	}
	if n != 1 {
		t.Errorf("purged = %d, want 1 (only the fully missing item)", n)
	}

	// Book A survives, with its present and missing files intact.
	var items int
	if err := db.QueryRowContext(ctx,
		`SELECT count(*) FROM media_items WHERE library_id = ?`, lib.ID).Scan(&items); err != nil {
		t.Fatal(err)
	}
	if items != 1 {
		t.Errorf("media_items after purge = %d, want 1", items)
	}
	var bookATitle string
	if err := db.QueryRowContext(ctx,
		`SELECT title FROM media_items WHERE library_id = ? AND path = ?`, lib.ID, "Book A").Scan(&bookATitle); err != nil {
		t.Fatalf("a non-missing item was purged: %v", err)
	}
	var files int
	if err := db.QueryRowContext(ctx, `
		SELECT count(*) FROM media_files f JOIN media_items i ON i.id = f.item_id
		WHERE i.library_id = ? AND i.path = ?`, lib.ID, "Book A").Scan(&files); err != nil {
		t.Fatal(err)
	}
	if files != 2 {
		t.Errorf("Book A files after purge = %d, want 2", files)
	}

	// The other library's missing item is untouched.
	var otherItems int
	if err := db.QueryRowContext(ctx,
		`SELECT count(*) FROM media_items WHERE library_id = ?`, other.ID).Scan(&otherItems); err != nil {
		t.Fatal(err)
	}
	if otherItems != 1 {
		t.Errorf("other library items after purge = %d, want 1 (purge must be scoped)", otherItems)
	}

	// A second purge has nothing left to remove.
	if n, err := PurgeMissing(ctx, db, lib.ID); err != nil || n != 0 {
		t.Errorf("second purge = %d, %v; want 0, nil", n, err)
	}
}