go project - add a migration and rename the dockerfiles so that Go is the primary

go/internal/api/handlers.go

@@ -0,0 +1,130 @@
+package api
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/michaeldileo/SafelyYouCodingChallenge/internal/store"
+)
+
+// Server wires HTTP handlers to the in-memory store.
+// Constructed in main and passed dependencies explicitly (no DI container).
+type Server struct {
+	store *store.Store
+}
+
+func NewServer(s *store.Store) *Server {
+	return &Server{store: s}
+}
+
+// Handler returns the HTTP routes for this API.
+func (s *Server) Handler() http.Handler {
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /healthz", s.healthz)
+	mux.HandleFunc("POST /api/v1/devices/{device_id}/heartbeat", s.postHeartbeat)
+	mux.HandleFunc("POST /api/v1/devices/{device_id}/stats", s.postStats)
+	mux.HandleFunc("GET /api/v1/devices/{device_id}/stats", s.getStats)
+	return mux
+}
+
+type heartbeatRequest struct {
+	SentAt time.Time `json:"sent_at"`
+}
+
+type uploadStatsRequest struct {
+	SentAt     time.Time `json:"sent_at"`     // accepted for contract; ignored in average
+	UploadTime int64     `json:"upload_time"` // nanoseconds
+}
+
+type getDeviceStatsResponse struct {
+	AvgUploadTime string  `json:"avg_upload_time"`
+	Uptime        float64 `json:"uptime"`
+}
+
+// OpenAPI NotFoundResponse / ErrorResponse both use {"msg": "..."}.
+type msgResponse struct {
+	Msg string `json:"msg"`
+}
+
+func (s *Server) healthz(w http.ResponseWriter, _ *http.Request) {
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write([]byte("ok"))
+}
+
+func (s *Server) postHeartbeat(w http.ResponseWriter, r *http.Request) {
+	id := store.DeviceID(r.PathValue("device_id"))
+	if !s.store.Known(id) {
+		writeJSON(w, http.StatusNotFound, msgResponse{
+			Msg: fmt.Sprintf("Device ID %s not found", id),
+		})
+		return
+	}
+
+	var req heartbeatRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeJSON(w, http.StatusInternalServerError, msgResponse{
+			Msg: "invalid request body",
+		})
+		return
+	}
+
+	if err := s.store.AddHeartbeat(id, req.SentAt); err != nil {
+		if errors.Is(err, store.ErrOutOfSequence) {
+			writeJSON(w, http.StatusInternalServerError, msgResponse{
+				Msg: "Attempted to add a timestamp that was out of sequence or invalid.",
+			})
+			return
+		}
+		writeJSON(w, http.StatusInternalServerError, msgResponse{Msg: err.Error()})
+		return
+	}
+
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func (s *Server) postStats(w http.ResponseWriter, r *http.Request) {
+	id := store.DeviceID(r.PathValue("device_id"))
+	if !s.store.Known(id) {
+		writeJSON(w, http.StatusNotFound, msgResponse{
+			Msg: fmt.Sprintf("Device ID %s not found", id),
+		})
+		return
+	}
+
+	var req uploadStatsRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeJSON(w, http.StatusInternalServerError, msgResponse{
+			Msg: "invalid request body",
+		})
+		return
+	}
+
+	// sent_at is decoded above but intentionally unused for the average.
+	s.store.AddUpload(id, time.Duration(req.UploadTime))
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func (s *Server) getStats(w http.ResponseWriter, r *http.Request) {
+	id := store.DeviceID(r.PathValue("device_id"))
+	if !s.store.Known(id) {
+		writeJSON(w, http.StatusNotFound, msgResponse{
+			Msg: fmt.Sprintf("Device ID %s not found", id),
+		})
+		return
+	}
+
+	avg := s.store.AverageUploadTime(id)
+	writeJSON(w, http.StatusOK, getDeviceStatsResponse{
+		AvgUploadTime: avg.String(), // HTTP-edge formatting (Q13)
+		Uptime:        s.store.Uptime(id),
+	})
+}
+
+func writeJSON(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(v)
+}