package home

import (
	"context"
	"database/sql"
	"testing"
)

type fixture struct {
	db     *sql.DB
	libA   int64
	libB   int64
	userA  int64
	userB  int64
	itemA  int64 // in libA
	itemA2 int64 // in libA, unstarted
	itemB  int64 // in libB
}

func setup(t *testing.T) fixture {
	t.Helper()
	db := testDB(t)
	ctx := context.Background()
	f := fixture{db: db}

	mk := func(q string, args ...any) int64 {
		var id int64
		if err := db.QueryRowContext(ctx, q, args...).Scan(&id); err != nil {
			t.Fatal(err)
		}
		return id
	}

	f.libA = mk(`INSERT INTO libraries (name, kind, root_path) VALUES ('A','ebooks','/a') RETURNING id`)
	f.libB = mk(`INSERT INTO libraries (name, kind, root_path) VALUES ('B','ebooks','/b') RETURNING id`)
	f.userA = mk(`INSERT INTO users (username, password_hash) VALUES ('a','x') RETURNING id`)
	f.userB = mk(`INSERT INTO users (username, password_hash) VALUES ('b','x') RETURNING id`)

	f.itemA = mk(`INSERT INTO media_items (library_id, kind, path, title) VALUES (?, 'ebooks','a1.epub','A One') RETURNING id`, f.libA)
	f.itemA2 = mk(`INSERT INTO media_items (library_id, kind, path, title) VALUES (?, 'ebooks','a2.epub','A Two') RETURNING id`, f.libA)
	f.itemB = mk(`INSERT INTO media_items (library_id, kind, path, title) VALUES (?, 'ebooks','b1.epub','B One') RETURNING id`, f.libB)

	// A file for each item, so progress rows can reference one. media_files.path
	// is globally unique, so each gets its own.
	for i, it := range []int64{f.itemA, f.itemA2, f.itemB} {
		if _, err := db.ExecContext(ctx,
			`INSERT INTO media_files (item_id, path, size) VALUES (?, ?, 1)`, it, "file-"+itoa(int64(i))); err != nil {
			t.Fatal(err)
		}
	}
	return f
}

func itoa(n int64) string {
	if n == 0 {
		return "0"
	}
	var b [20]byte
	i := len(b)
	for n > 0 {
		i--
		b[i] = byte('0' + n%10)
		n /= 10
	}
	return string(b[i:])
}

func startItem(t *testing.T, f fixture, userID, itemID int64) {
	t.Helper()
	var fileID int64
	if err := f.db.QueryRow(`SELECT id FROM media_files WHERE item_id = ? LIMIT 1`, itemID).Scan(&fileID); err != nil {
		t.Fatal(err)
	}
	if _, err := f.db.Exec(`
		INSERT INTO progress (user_id, item_id, file_id, kind, position, percent, finished)
		VALUES (?, ?, ?, 'ebooks', 1, 0.5, 0)`, userID, itemID, fileID); err != nil {
		t.Fatal(err)
	}
}

func ids(items []shelfItem) []int64 {
	out := make([]int64, len(items))
	for i, it := range items {
		out[i] = it.ID
	}
	return out
}

func contains64(hay []int64, needle int64) bool {
	for _, h := range hay {
		if h == needle {
			return true
		}
	}
	return false
}

func TestMostViewedIsPerUser(t *testing.T) {
	f := setup(t)
	ctx := context.Background()

	for i := 0; i < 3; i++ {
		if _, err := RecordView(ctx, f.db, f.userA, f.itemA); err != nil {
			t.Fatal(err)
		}
	}
	if _, err := RecordView(ctx, f.db, f.userA, f.itemA2); err != nil {
		t.Fatal(err)
	}

	got, err := MostViewed(ctx, f.db, f.userA, []int64{f.libA}, 10)
	if err != nil {
		t.Fatal(err)
	}
	if len(got) != 2 {
		t.Fatalf("got %d, want 2: %v", len(got), ids(got))
	}
	if got[0].ID != f.itemA || got[0].Views != 3 {
		t.Errorf("first = id %d with %d views, want id %d with 3", got[0].ID, got[0].Views, f.itemA)
	}

	// User B has viewed nothing.
	other, err := MostViewed(ctx, f.db, f.userB, []int64{f.libA}, 10)
	if err != nil {
		t.Fatal(err)
	}
	if len(other) != 0 {
		t.Errorf("user B sees %v, want nothing", ids(other))
	}
}

// TestScopingRespectsLibraryAndUser guards the parameter order in the
// suggestions and explore queries, where the IN list precedes the user id.
// Getting it wrong silently swaps a user id for a library id.
func TestScopingRespectsLibraryAndUser(t *testing.T) {
	f := setup(t)
	ctx := context.Background()

	// User A started itemA, which lives in libA.
	startItem(t, f, f.userA, f.itemA)

	// Suggestions: only libA, only unstarted.
	sugg, err := Suggestions(ctx, f.db, f.userA, []int64{f.libA}, 10)
	if err != nil {
		t.Fatal(err)
	}
	for _, s := range sugg {
		if s.LibraryID != f.libA {
			t.Errorf("suggestion %d is from library %d, want only %d", s.ID, s.LibraryID, f.libA)
		}
		if s.ID == f.itemA {
			t.Error("a started item was suggested")
		}
	}
	if len(sugg) == 0 {
		t.Fatal("no suggestions at all")
	}

	// Explore: same scoping, and it must not include the in-progress item.
	explore, err := Explore(ctx, f.db, f.userA, []int64{f.libA}, 10)
	if err != nil {
		t.Fatal(err)
	}
	if len(explore) == 0 {
		t.Fatal("explore returned nothing")
	}
	for _, e := range explore {
		if e.LibraryID != f.libA {
			t.Errorf("explore item %d is from library %d, want only %d", e.ID, e.LibraryID, f.libA)
		}
		if e.ID == f.itemA {
			t.Error("explore included an in-progress item")
		}
	}

	// User B, restricted to libB, must not see libA content at all.
	suggB, err := Suggestions(ctx, f.db, f.userB, []int64{f.libB}, 10)
	if err != nil {
		t.Fatal(err)
	}
	for _, s := range suggB {
		if s.LibraryID != f.libB {
			t.Errorf("user B suggestion %d leaked from library %d", s.ID, s.LibraryID)
		}
	}
	if contains64(func() []int64 {
		out := make([]int64, len(suggB))
		for i, s := range suggB {
			out[i] = s.ID
		}
		return out
	}(), f.itemA) {
		t.Error("user B was suggested an item from a library they cannot see")
	}
}

func TestSuggestionsExplainThemselves(t *testing.T) {
	f := setup(t)
	ctx := context.Background()

	// Give user A an author relationship on the started item.
	if _, err := f.db.Exec(`
		INSERT INTO people (name) VALUES ('Ursula Le Guin')`); err != nil {
		t.Fatal(err)
	}
	var personID int64
	if err := f.db.QueryRow(`SELECT id FROM people WHERE name = 'Ursula Le Guin'`).Scan(&personID); err != nil {
		t.Fatal(err)
	}
	if _, err := f.db.Exec(
		`INSERT INTO item_people (item_id, person_id, role, ord) VALUES (?, ?, 'author', 0)`,
		f.itemA, personID); err != nil {
		t.Fatal(err)
	}
	// And on the candidate.
	if _, err := f.db.Exec(
		`INSERT INTO item_people (item_id, person_id, role, ord) VALUES (?, ?, 'author', 0)`,
		f.itemA2, personID); err != nil {
		t.Fatal(err)
	}
	startItem(t, f, f.userA, f.itemA)

	sugg, err := Suggestions(ctx, f.db, f.userA, []int64{f.libA}, 10)
	if err != nil {
		t.Fatal(err)
	}
	if len(sugg) == 0 {
		t.Fatal("no suggestions")
	}
	if sugg[0].ID != f.itemA2 {
		t.Errorf("first suggestion = %d, want the same-author item %d", sugg[0].ID, f.itemA2)
	}
	if sugg[0].Reason != "More by Ursula Le Guin" {
		t.Errorf("reason = %q", sugg[0].Reason)
	}
}

func TestRecordViewCounts(t *testing.T) {
	f := setup(t)
	ctx := context.Background()

	for i := 1; i <= 4; i++ {
		n, err := RecordView(ctx, f.db, f.userA, f.itemA)
		if err != nil {
			t.Fatal(err)
		}
		if n != i {
			t.Errorf("view %d returned count %d", i, n)
		}
	}
}