Add existing codebase

link/dto.go

@@ -0,0 +1,26 @@
+package link
+
+import (
+	"net/url"
+	"time"
+)
+
+type CreationModel struct {
+	Id          string `json:"id"`
+	Name        string `json:"name"`
+	RedirectURL string `json:"redirectUrl"`
+}
+
+func (m *CreationModel) MapModelToEntity() (*Link, error) {
+	u, err := url.Parse(m.RedirectURL)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Link{
+		Id:           m.Id,
+		Name:         m.Name,
+		RedirectURL:  *u,
+		CreationTime: time.Now().UTC(),
+	}, nil
+}

link/entity.go

@@ -0,0 +1,13 @@
+package link
+
+import (
+	"net/url"
+	"time"
+)
+
+type Link struct {
+	Id           string
+	Name         string
+	RedirectURL  url.URL
+	CreationTime time.Time
+}

link/handlers.go

@@ -0,0 +1,63 @@
+package link
+
+import (
+	"encoding/json"
+	"github.com/jackc/pgx/v4/pgxpool"
+	"github.com/labstack/echo/v4"
+	"net/http"
+)
+
+func creationHandler(c echo.Context, pool *pgxpool.Pool) error {
+	var model CreationModel
+	if err := json.NewDecoder(c.Request().Body).Decode(&model); err != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, "Invalid data format.")
+	}
+
+	entity, err := model.MapModelToEntity()
+	if err != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, "Invalid URL.")
+	}
+
+	rep := PgRepository{pool: pool}
+
+	link, err := rep.FindById(entity.Id)
+	if err != nil {
+		return echo.NewHTTPError(http.StatusInternalServerError)
+	}
+
+	if link != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, "Link with given ID already exists.")
+	}
+
+	if err = rep.Save(entity); err != nil {
+		return echo.NewHTTPError(http.StatusInternalServerError)
+	}
+
+	return c.NoContent(http.StatusCreated)
+}
+
+func redirectHandler(c echo.Context, pool *pgxpool.Pool) error {
+	linkId := c.Param("id")
+
+	rep := PgRepository{pool: pool}
+
+	link, err := rep.FindById(linkId)
+	if err != nil {
+		return echo.NewHTTPError(http.StatusInternalServerError)
+	}
+
+	if link == nil {
+		return echo.NewHTTPError(http.StatusNotFound, "Link with given ID was not found.")
+	}
+
+	return c.Redirect(http.StatusSeeOther, link.RedirectURL.String())
+}
+
+func AddHandlers(s *echo.Echo, pool *pgxpool.Pool) {
+	s.POST("", func(ctx echo.Context) error {
+		return creationHandler(ctx, pool)
+	})
+	s.GET("/:id", func(ctx echo.Context) error {
+		return redirectHandler(ctx, pool)
+	})
+}

link/repository.go

@@ -0,0 +1,95 @@
+package link
+
+import (
+	"context"
+	"errors"
+	"github.com/jackc/pgtype"
+	"github.com/jackc/pgx/v4"
+	"github.com/jackc/pgx/v4/pgxpool"
+	"net/url"
+)
+
+type Repository interface {
+	Save(link *Link) error
+	FindById(id string) (*Link, error)
+	DeleteById(id string) error
+}
+
+type PgRepository struct {
+	pool *pgxpool.Pool
+}
+
+func (r *PgRepository) Save(link *Link) error {
+	ctx := context.Background()
+	tx, err := r.pool.Begin(ctx)
+	if err != nil {
+		return err
+	}
+
+	sql := `
+		INSERT INTO links (id, name, redirect_url, creation_time) 
+		VALUES ($1, $2, $3, $4::timestamp)
+	`
+
+	_, err = tx.Exec(ctx, sql, link.Id, link.Name, link.RedirectURL.String(), link.CreationTime.Format("2006-01-02 15:04:05"))
+	if err != nil {
+		_ = tx.Rollback(ctx)
+		return err
+	}
+
+	if err = tx.Commit(ctx); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (r *PgRepository) FindById(id string) (*Link, error) {
+	ctx := context.Background()
+	tx, err := r.pool.Begin(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	sql := `
+		SELECT id, name, redirect_url, creation_time
+		FROM links
+		WHERE id = $1
+	`
+
+	entity, err := mapRowToEntity(tx.QueryRow(ctx, sql, id))
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, nil
+		} else {
+			_ = tx.Rollback(ctx)
+			return nil, err
+		}
+	}
+
+	if err = tx.Commit(ctx); err != nil {
+		return nil, err
+	}
+
+	return entity, nil
+}
+
+func mapRowToEntity(r pgx.Row) (*Link, error) {
+	var entity Link
+	var urlStr string
+	var t pgtype.Timestamp
+
+	if err := r.Scan(&entity.Id, &entity.Name, &urlStr, &t); err != nil {
+		return nil, err
+	}
+
+	u, err := url.Parse(urlStr)
+	if err != nil {
+		return nil, err
+	}
+
+	entity.RedirectURL = *u
+	entity.CreationTime = t.Time
+
+	return &entity, nil
+}