package db

import (
	"context"
	"database/sql"
	"errors"
	"os"
	"path/filepath"
	"testing"
	"time"
)

func tempDB(t *testing.T) string {
	t.Helper()
	dir := t.TempDir()
	return filepath.Join(dir, "test.db")
}

func mustOpen(t *testing.T) *sql.DB {
	t.Helper()
	path := tempDB(t)
	database, err := Open(path)
	if err != nil {
		t.Fatalf("Open failed: %v", err)
	}
	t.Cleanup(func() { _ = database.Close() })
	return database
}

func mustOpenAndMigrate(t *testing.T) *sql.DB {
	t.Helper()
	database := mustOpen(t)
	if err := Migrate(database); err != nil {
		t.Fatalf("Migrate failed: %v", err)
	}
	return database
}

func TestOpenAndPing(t *testing.T) {
	database := mustOpen(t)
	if err := database.Ping(); err != nil {
		t.Fatalf("Ping failed: %v", err)
	}
}

func TestOpenCreatesFile(t *testing.T) {
	path := tempDB(t)
	database, err := Open(path)
	if err != nil {
		t.Fatalf("Open failed: %v", err)
	}
	t.Cleanup(func() { _ = database.Close() })

	if _, err := os.Stat(path); os.IsNotExist(err) {
		t.Fatal("database file was not created")
	}
}

func TestMigrate(t *testing.T) {
	database := mustOpenAndMigrate(t)

	tables := []string{
		"metadata", "tags", "categories", "publishers", "citations",
		"authors", "artifacts", "artifact_tags", "artifact_categories",
		"artifacts_history", "artifact_snapshots", "blobs", "schema_version",
	}
	for _, table := range tables {
		var name string
		row := database.QueryRow(`SELECT name FROM sqlite_master WHERE type='table' AND name=?`, table)
		if err := row.Scan(&name); err != nil {
			t.Errorf("table %q not found after migration: %v", table, err)
		}
	}
}

func TestMigrateIdempotent(t *testing.T) {
	database := mustOpenAndMigrate(t)

	if err := Migrate(database); err != nil {
		t.Fatalf("second Migrate failed: %v", err)
	}
}

func TestStartTXAndEndTX(t *testing.T) {
	database := mustOpenAndMigrate(t)
	ctx := context.Background()

	tx, err := StartTX(ctx, database)
	if err != nil {
		t.Fatalf("StartTX failed: %v", err)
	}

	_, err = tx.ExecContext(ctx, `INSERT INTO tags (id, tag) VALUES ('test-id', 'test-tag')`)
	if err != nil {
		t.Fatalf("INSERT failed: %v", err)
	}

	if err := EndTX(tx, nil); err != nil {
		t.Fatalf("EndTX (commit) failed: %v", err)
	}

	var tag string
	row := database.QueryRow(`SELECT tag FROM tags WHERE id='test-id'`)
	if err := row.Scan(&tag); err != nil {
		t.Fatalf("committed row not found: %v", err)
	}
	if tag != "test-tag" {
		t.Fatalf("expected 'test-tag', got %q", tag)
	}
}

func TestEndTXRollback(t *testing.T) {
	database := mustOpenAndMigrate(t)
	ctx := context.Background()

	tx, err := StartTX(ctx, database)
	if err != nil {
		t.Fatalf("StartTX failed: %v", err)
	}

	_, err = tx.ExecContext(ctx, `INSERT INTO tags (id, tag) VALUES ('rollback-id', 'rollback-tag')`)
	if err != nil {
		t.Fatalf("INSERT failed: %v", err)
	}

	simErr := context.DeadlineExceeded
	if err := EndTX(tx, simErr); !errors.Is(err, simErr) {
		t.Fatalf("EndTX should return the original error, got: %v", err)
	}

	var tag string
	row := database.QueryRow(`SELECT tag FROM tags WHERE id='rollback-id'`)
	if err := row.Scan(&tag); err == nil {
		t.Fatal("rolled-back row should not be found")
	}
}

func TestToDBTimeAndFromDBTime(t *testing.T) {
	original := time.Date(2024, 6, 15, 14, 30, 0, 0, time.UTC)
	s := ToDBTime(original)

	if s != "2024-06-15 14:30:00" {
		t.Fatalf("unexpected time string: %q", s)
	}

	parsed, err := FromDBTime(s, nil)
	if err != nil {
		t.Fatalf("FromDBTime failed: %v", err)
	}

	if !parsed.Equal(original) {
		t.Fatalf("round-trip failed: got %v, want %v", parsed, original)
	}
}

func TestFromDBTimeWithLocation(t *testing.T) {
	s := "2024-06-15 14:30:00"
	loc, err := time.LoadLocation("America/New_York")
	if err != nil {
		t.Skipf("timezone not available: %v", err)
	}

	parsed, err := FromDBTime(s, loc)
	if err != nil {
		t.Fatalf("FromDBTime failed: %v", err)
	}

	if parsed.Location() != loc {
		t.Fatalf("expected location %v, got %v", loc, parsed.Location())
	}
}

func TestFromDBTimeInvalid(t *testing.T) {
	_, err := FromDBTime("not-a-date", nil)
	if err == nil {
		t.Fatal("expected error for invalid time string")
	}
}

func TestForeignKeysEnabled(t *testing.T) {
	database := mustOpen(t)

	var fk int
	row := database.QueryRow(`PRAGMA foreign_keys`)
	if err := row.Scan(&fk); err != nil {
		t.Fatalf("PRAGMA foreign_keys failed: %v", err)
	}
	if fk != 1 {
		t.Fatalf("foreign keys should be enabled, got %d", fk)
	}
}

func TestSchemaVersion(t *testing.T) {
	database := mustOpenAndMigrate(t)

	version, err := getCurrentVersion(database)
	if err != nil {
		t.Fatalf("getCurrentVersion failed: %v", err)
	}
	if version < 1 {
		t.Fatalf("expected schema version >= 1, got %d", version)
	}
}