feat: add contact repository and base repository for shared db logic

internal/repository/base_repository.go

@@ -0,0 +1,76 @@
+package repository
+
+import (
+	"database/sql"
+	"fmt"
+)
+
+type baseRepository[T any] struct {
+	db        *sql.DB
+	tableName string
+}
+
+func NewBaseRepository[T any](db *sql.DB, tableName string) Repository[T] {
+	return &baseRepository[T]{
+		db:        db,
+		tableName: tableName,
+	}
+}
+
+func (r *baseRepository[T]) BuildQuery(baseQuery string) string {
+	return fmt.Sprintf(baseQuery, r.tableName)
+}
+
+func (r *baseRepository[T]) GetDB() *sql.DB {
+	return r.db
+}
+
+func (r *baseRepository[T]) GetByID(id int) (*T, error) {
+	var entity T
+
+	query := r.BuildQuery("SELECT * FROM %s WHERE id = ?")
+	err := r.db.QueryRow(
+		query,
+		id,
+	).Scan(entity)
+
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return nil, nil
+		}
+		return nil, err
+	}
+
+	return &entity, nil
+}
+
+func (r *baseRepository[T]) GetAll() ([]T, error) {
+	query := r.BuildQuery("SELECT * FROM %s ORDER BY id DESC")
+
+	rows, err := r.db.Query(query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	entities := make([]T, 0)
+	for rows.Next() {
+		var entity T
+		if err := rows.Scan(entity); err != nil {
+			return nil, err
+		}
+		entities = append(entities, entity)
+	}
+
+	if err = rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return entities, nil
+}
+
+func (r *baseRepository[T]) Delete(id int) error {
+	query := r.BuildQuery("DELETE %s WHERE id = ? LIMIT 1")
+	_, err := r.db.Exec(query, id)
+	return err
+}