Update link repository

Add timeout to contexts.
Add method for retrieving all links.

link/repository.go

@@ -7,11 +7,13 @@ import (
 	"github.com/jackc/pgx/v4"
 	"github.com/jackc/pgx/v4/pgxpool"
 	"net/url"
+	"time"
 )
 
 type Repository interface {
 	Save(link *Link) error
 	FindById(id string) (*Link, error)
+	FindAll(limit int, offset int) ([]Link, error)
 	DeleteById(id string) error
 }
 
@@ -20,7 +22,9 @@ type PgRepository struct {
 }
 
 func (r *PgRepository) Save(link *Link) error {
-	ctx := context.Background()
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
 	tx, err := r.pool.Begin(ctx)
 	if err != nil {
 		return err
@@ -45,7 +49,9 @@ func (r *PgRepository) Save(link *Link) error {
 }
 
 func (r *PgRepository) FindById(id string) (*Link, error) {
-	ctx := context.Background()
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
 	tx, err := r.pool.Begin(ctx)
 	if err != nil {
 		return nil, err
@@ -74,8 +80,63 @@ func (r *PgRepository) FindById(id string) (*Link, error) {
 	return entity, nil
 }
 
+func (r *PgRepository) FindAll(limit int, offset int) ([]Link, error) {
+	if limit < 0 {
+		return nil, errors.New("limit can't be negative")
+	}
+	if offset < 0 {
+		return nil, errors.New("offset can't be negative")
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	tx, err := r.pool.Begin(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	sql := `
+		SELECT id, name, redirect_url, creation_time
+		FROM links
+		LIMIT $1
+		OFFSET $2
+	`
+
+	rows, err := tx.Query(ctx, sql, limit, offset)
+	if err != nil {
+		_ = tx.Rollback(ctx)
+		return nil, err
+	}
+	defer rows.Close()
+
+	links := make([]Link, 0)
+	for rows.Next() {
+		link, err := mapRowToEntity(rows)
+		if err != nil {
+			_ = tx.Rollback(ctx)
+			return nil, err
+		}
+
+		links = append(links, *link)
+	}
+
+	if err = rows.Err(); err != nil {
+		_ = tx.Rollback(ctx)
+		return nil, err
+	}
+
+	if err = tx.Commit(ctx); err != nil {
+		return nil, err
+	}
+
+	return links, nil
+}
+
 func (r *PgRepository) DeleteById(id string) error {
-	ctx := context.Background()
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
 	tx, err := r.pool.Begin(ctx)
 	if err != nil {
 		return err
@@ -98,14 +159,23 @@ func (r *PgRepository) DeleteById(id string) error {
 	return nil
 }
 
-func mapRowToEntity(r pgx.Row) (*Link, error) {
+func mapRowToEntity(r interface{}) (*Link, error) {
 	var entity Link
 	var urlStr string
 	var t pgtype.Timestamp
 
-	if err := r.Scan(&entity.Id, &entity.Name, &urlStr, &t); err != nil {
+	switch v := r.(type) {
+	case pgx.Row:
+		if err := v.Scan(&entity.Id, &entity.Name, &urlStr, &t); err != nil {
 			return nil, err
 		}
+	case pgx.Rows:
+		if err := v.Scan(&entity.Id, &entity.Name, &urlStr, &t); err != nil {
+			return nil, err
+		}
+	default:
+		return nil, errors.New("unsupported type")
+	}
 
 	u, err := url.Parse(urlStr)
 	if err != nil {