add paste functionality

Backend/paste/handlers.go

@@ -0,0 +1,118 @@
+package paste
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+	"time"
+)
+
+type Handlers struct {
+	store *Store
+}
+
+func NewHandlers(store *Store) *Handlers {
+	return &Handlers{store: store}
+}
+
+type createRequest struct {
+	Title    string `json:"title"`
+	Content  string `json:"content"`
+	Language string `json:"language"`
+	Expiry   int    `json:"expiry"`
+}
+
+func writeJSON(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(v)
+}
+
+func writeError(w http.ResponseWriter, status int, msg string) {
+	writeJSON(w, status, map[string]string{"error": msg})
+}
+
+func (h *Handlers) Create(w http.ResponseWriter, r *http.Request) {
+	r.Body = http.MaxBytesReader(w, r.Body, 1_100_000)
+
+	var req createRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+	if req.Content == "" {
+		writeError(w, http.StatusBadRequest, "content is required")
+		return
+	}
+	if len(req.Content) > 1_000_000 {
+		writeError(w, http.StatusRequestEntityTooLarge, "content exceeds 1,000,000 characters")
+		return
+	}
+	if len(req.Title) > 200 {
+		writeError(w, http.StatusBadRequest, "title exceeds 200 characters")
+		return
+	}
+
+	p := &Paste{
+		Title:    req.Title,
+		Content:  req.Content,
+		Language: req.Language,
+	}
+
+	if req.Expiry < 1 || req.Expiry > 10 {
+		writeError(w, http.StatusBadRequest, "expiry must be between 1 and 10 minutes")
+		return
+	}
+	t := time.Now().Add(time.Duration(req.Expiry) * time.Minute)
+	p.ExpiresAt = &t
+
+	if err := h.store.Create(p); err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to create paste")
+		return
+	}
+
+	writeJSON(w, http.StatusCreated, map[string]string{
+		"id":  p.ID,
+		"url": "/paste/" + p.ID,
+	})
+}
+
+func (h *Handlers) Get(w http.ResponseWriter, r *http.Request) {
+	id := r.PathValue("id")
+	p, err := h.store.Get(id)
+	if errors.Is(err, ErrNotFound) {
+		writeError(w, http.StatusNotFound, "paste not found")
+		return
+	}
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to retrieve paste")
+		return
+	}
+	if p.ExpiresAt != nil && time.Now().After(*p.ExpiresAt) {
+		h.store.Delete(id)
+		writeError(w, http.StatusGone, "paste has expired")
+		return
+	}
+	writeJSON(w, http.StatusOK, p)
+}
+
+func (h *Handlers) GetRaw(w http.ResponseWriter, r *http.Request) {
+	id := r.PathValue("id")
+	p, err := h.store.Get(id)
+	if errors.Is(err, ErrNotFound) {
+		http.Error(w, "paste not found", http.StatusNotFound)
+		return
+	}
+	if err != nil {
+		http.Error(w, "failed to retrieve paste", http.StatusInternalServerError)
+		return
+	}
+	if p.ExpiresAt != nil && time.Now().After(*p.ExpiresAt) {
+		h.store.Delete(id)
+		http.Error(w, "paste has expired", http.StatusGone)
+		return
+	}
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	w.Header().Set("X-Content-Type-Options", "nosniff")
+	w.Write([]byte(p.Content))
+}