Restructure data layer (#2532)

* Add new txn manager interface
* Add txn management to sqlite
* Rename get to getByID
* Add contexts to repository methods
* Update query builders
* Add context to reader writer interfaces
* Use repository in resolver
* Tighten interfaces
* Tighten interfaces in dlna
* Tighten interfaces in match package
* Tighten interfaces in scraper package
* Tighten interfaces in scan code
* Tighten interfaces on autotag package
* Remove ReaderWriter usage
* Merge database package into sqlite

pkg/sqlite/custom_migrations.go

@@ -0,0 +1,79 @@
+package sqlite
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/stashapp/stash/pkg/logger"
+	"github.com/stashapp/stash/pkg/txn"
+)
+
+func (db *Database) runCustomMigrations() error {
+	if err := db.createImagesChecksumIndex(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (db *Database) createImagesChecksumIndex() error {
+	return txn.WithTxn(context.Background(), db, func(ctx context.Context) error {
+		tx, err := getTx(ctx)
+		if err != nil {
+			return err
+		}
+
+		row := tx.QueryRow("SELECT 1 AS found FROM sqlite_master WHERE type = 'index' AND name = 'images_checksum_unique'")
+		err = row.Err()
+		if err != nil && !errors.Is(err, sql.ErrNoRows) {
+			return err
+		}
+
+		if err == nil {
+			var found bool
+			if err := row.Scan(&found); err != nil && err != sql.ErrNoRows {
+				return fmt.Errorf("error while scanning for index: %w", err)
+			}
+			if found {
+				return nil
+			}
+		}
+
+		_, err = tx.Exec("CREATE UNIQUE INDEX images_checksum_unique ON images (checksum)")
+		if err == nil {
+			_, err = tx.Exec("DROP INDEX IF EXISTS index_images_checksum")
+			if err != nil {
+				logger.Errorf("Failed to remove surrogate images.checksum index: %s", err)
+			}
+			logger.Info("Created unique constraint on images table")
+			return nil
+		}
+
+		_, err = tx.Exec("CREATE INDEX IF NOT EXISTS index_images_checksum ON images (checksum)")
+		if err != nil {
+			logger.Errorf("Unable to create index on images.checksum: %s", err)
+		}
+
+		var result []struct {
+			Checksum string `db:"checksum"`
+		}
+
+		err = tx.Select(&result, "SELECT checksum FROM images GROUP BY checksum HAVING COUNT(1) > 1")
+		if err != nil && !errors.Is(err, sql.ErrNoRows) {
+			logger.Errorf("Unable to determine non-unique image checksums: %s", err)
+			return nil
+		}
+
+		checksums := make([]string, len(result))
+		for i, res := range result {
+			checksums[i] = res.Checksum
+		}
+
+		logger.Warnf("The following duplicate image checksums have been found. Please remove the duplicates and restart. %s", strings.Join(checksums, ", "))
+
+		return nil
+	})
+}