package db

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

// testLogger returns a logger that writes nowhere, keeping test output clean.
func testLogger() *slog.Logger {
	return slog.New(slog.NewTextHandler(io.Discard, nil))
}

func TestOpen_InMemory_正常(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	db, err := Open(ctx, ":memory:", testLogger())
	if err != nil {
		t.Fatalf("Open(:memory:) error: %v", err)
	}
	defer db.Close()

	if err := db.PingContext(ctx); err != nil {
		t.Fatalf("ping in-memory db: %v", err)
	}

	var n int
	if err := db.QueryRowContext(ctx, "SELECT count(*) FROM sqlite_master WHERE type='table'").Scan(&n); err != nil {
		t.Fatalf("query sqlite_master: %v", err)
	}
	if n != 0 {
		t.Fatalf("expected no tables before migrations, got %d", n)
	}
}

func TestOpen_InMemory_NilLogger_正常(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	// A nil logger must not panic and must produce a usable connection.
	db, err := Open(ctx, ":memory:", nil)
	if err != nil {
		t.Fatalf("Open with nil logger error: %v", err)
	}
	defer db.Close()
	if err := db.PingContext(ctx); err != nil {
		t.Fatalf("ping with nil logger: %v", err)
	}
}

func TestOpen_InMemory_Isolation_并发(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	db1, err := Open(ctx, ":memory:", testLogger())
	if err != nil {
		t.Fatalf("open db1: %v", err)
	}
	defer db1.Close()
	db2, err := Open(ctx, ":memory:", testLogger())
	if err != nil {
		t.Fatalf("open db2: %v", err)
	}
	defer db2.Close()

	if _, err := db1.ExecContext(ctx, "CREATE TABLE t1(x)"); err != nil {
		t.Fatalf("create table in db1: %v", err)
	}

	var n int
	if err := db2.QueryRowContext(ctx, "SELECT count(*) FROM sqlite_master WHERE name='t1'").Scan(&n); err != nil {
		t.Fatalf("query db2: %v", err)
	}
	if n != 0 {
		t.Fatalf("db2 must not see db1's table (isolation broken), count=%d", n)
	}
}

func TestOpen_File_正常(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	path := filepath.Join(t.TempDir(), "cyrene.db")
	db, err := Open(ctx, path, testLogger())
	if err != nil {
		t.Fatalf("Open(file) error: %v", err)
	}
	defer db.Close()

	if err := db.PingContext(ctx); err != nil {
		t.Fatalf("ping file db: %v", err)
	}

	// Persistence across a reopen with the same DSN.
	db.ExecContext(ctx, "CREATE TABLE p(x)")
	db.Close()

	db2, err := Open(ctx, path, testLogger())
	if err != nil {
		t.Fatalf("reopen(file) error: %v", err)
	}
	defer db2.Close()
	var n int
	if err := db2.QueryRowContext(ctx, "SELECT count(*) FROM sqlite_master WHERE name='p'").Scan(&n); err != nil {
		t.Fatalf("query reopened db: %v", err)
	}
	if n != 1 {
		t.Fatalf("expected table p to persist across reopen, count=%d", n)
	}
}

func TestOpen_BlankPath_异常(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	for _, path := range []string{"", "   "} {
		if _, err := Open(ctx, path, testLogger()); !errors.Is(err, ErrInvalidPath) {
			t.Fatalf("Open(%q) err = %v, want wrap of ErrInvalidPath", path, err)
		}
	}
}

func TestOpen_MissingParentDir_异常(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	// Parent directory does not exist, so the connection cannot be established.
	path := filepath.Join(t.TempDir(), "does-not-exist", "cyrene.db")
	if _, err := Open(ctx, path, testLogger()); err == nil {
		t.Fatalf("Open(%q) expected error for missing parent dir, got nil", path)
	}
}