draft ingest csv handler

README.md

@@ -6,7 +6,15 @@ Prueba técnica para el puesto de desarrollador Go/C++
 
 Compilar todos los servicios e iniciar los contenedores Docker.
 
-`docker compose --env-file <path/to/file> up --build`
+```bash
+docker compose --env-file <path/to/file> up --build`
+```
+
+Hacer petición POST con fichero a `/ingest/csv`
+
+```bash
+curl -X POST http://localhost:8080/ingest/csv -F "file=@meteo.csv"
+```
 
 ## Decisiones técnica
 

service_a/internal/domains/meteo/domain.go

@@ -44,4 +44,7 @@ var (
 	ErrMinTempOutOfRange          = errors.New("min temp out of range (must be >= -20°C)")
 	ErrRainfallOutOfRange         = errors.New("rainfall out of range (must be 0-500 mm)")
 	ErrCloudinessOutOfRange       = errors.New("cloudiness out of range (must be 0-100%)")
+	ErrParsingForm                = errors.New("error parsing form")
+	ErrRetrievingFile             = errors.New("error retrieving file")
+	ErrReadingFile                = errors.New("error reading file")
 )

service_a/internal/domains/meteo/handlers.go

@@ -1,8 +1,15 @@
 package meteo
 
 import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
 	"fmt"
+	"io"
+	"log/slog"
 	"net/http"
+	"time"
 )
 
 type Handler struct{}
@@ -12,7 +19,60 @@ func NewHandler() *Handler {
 }
 
 func (h *Handler) IngestCSV(w http.ResponseWriter, r *http.Request) {
-	fmt.Fprintf(w, "hello from csv")
+	err := r.ParseMultipartForm(10 << 20)
+	if err != nil {
+		http.Error(w, ErrParsingForm.Error(), http.StatusBadRequest)
+		return
+	}
+
+	file, header, err := r.FormFile("file")
+	if err != nil {
+		http.Error(w, ErrRetrievingFile.Error(), http.StatusBadRequest)
+		return
+	}
+	defer file.Close()
+
+	content, err := io.ReadAll(file)
+	if err != nil {
+		http.Error(w, ErrReadingFile.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	hash := sha256.Sum256(content)
+	checksum := hex.EncodeToString(hash[:])
+
+	fileStats := &FileStats{
+		FileChecksum: checksum,
+	}
+
+	start := time.Now()
+
+	csvParser := &CSV{}
+	inserted, rejected, err := csvParser.Parse(bytes.NewReader(content), fileStats)
+	if err != nil {
+		slog.Error(ErrCannotParseFile.Error(),
+			"filename", header.Filename,
+			"error", err)
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	fileStats.ElapsedMS = int(time.Since(start).Milliseconds())
+
+	slog.Info("CSV file processed",
+		"filename", header.Filename,
+		"rows_inserted", fileStats.RowsInserted,
+		"rows_rejected", fileStats.RowsRejected,
+		"elapsed_ms", fileStats.ElapsedMS,
+		"file_checksum", fileStats.FileChecksum,
+		"inserted_data", inserted,
+		"rejected_data", rejected,
+	)
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(H{
+		"stats": fileStats,
+	})
 }
 
 func (h *Handler) IngestExcel(w http.ResponseWriter, r *http.Request) {