From e46b71be51333e56ffc233e0523901431d0f9442 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pedro=20P=C3=A9rez?= <hola@pedroperez.dev>
Date: Thu, 23 Oct 2025 03:41:02 +0200
Subject: [PATCH] draft ingest csv handler

---
 README.md                                    | 10 +++-
 service_a/internal/domains/meteo/domain.go   | 33 ++++++-----
 service_a/internal/domains/meteo/handlers.go | 62 +++++++++++++++++++-
 3 files changed, 88 insertions(+), 17 deletions(-)

diff --git a/README.md b/README.md
index 5ba1a7f..cf96f78 100644
--- a/README.md
+++ b/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
 
diff --git a/service_a/internal/domains/meteo/domain.go b/service_a/internal/domains/meteo/domain.go
index 9f12793..8a3941b 100644
--- a/service_a/internal/domains/meteo/domain.go
+++ b/service_a/internal/domains/meteo/domain.go
@@ -29,19 +29,22 @@ type FileStats struct {
 }
 
 var (
-	ErrCannotParseFile             = errors.New("cannot parse file")
-	ErrValidateRecord              = errors.New("error validating record")
-	ErrRecordNotValid              = errors.New("record not valid")
-	ErrReadingCSVHeader            = errors.New("error reading CSV header")
-	ErrReadingCSVRow               = errors.New("error reading CSV row")
-	ErrMissingOrInvalidDateField   = errors.New("missing or invalid date field")
-	ErrMissingOrInvalidCityField   = errors.New("missing or invalid city field")
-	ErrMissingOrInvalidMaxTemp     = errors.New("missing or invalid max temp field")
-	ErrMissingOrInvalidMinTemp     = errors.New("missing or invalid min temp field")
-	ErrMissingOrInvalidRainfall    = errors.New("missing or invalid rainfall field")
-	ErrMissingOrInvalidCloudiness  = errors.New("missing or invalid cloudiness field")
-	ErrMaxTempOutOfRange           = errors.New("max temp out of range (must be <= 60°C)")
-	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%)")
+	ErrCannotParseFile            = errors.New("cannot parse file")
+	ErrValidateRecord             = errors.New("error validating record")
+	ErrRecordNotValid             = errors.New("record not valid")
+	ErrReadingCSVHeader           = errors.New("error reading CSV header")
+	ErrReadingCSVRow              = errors.New("error reading CSV row")
+	ErrMissingOrInvalidDateField  = errors.New("missing or invalid date field")
+	ErrMissingOrInvalidCityField  = errors.New("missing or invalid city field")
+	ErrMissingOrInvalidMaxTemp    = errors.New("missing or invalid max temp field")
+	ErrMissingOrInvalidMinTemp    = errors.New("missing or invalid min temp field")
+	ErrMissingOrInvalidRainfall   = errors.New("missing or invalid rainfall field")
+	ErrMissingOrInvalidCloudiness = errors.New("missing or invalid cloudiness field")
+	ErrMaxTempOutOfRange          = errors.New("max temp out of range (must be <= 60°C)")
+	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")
 )
diff --git a/service_a/internal/domains/meteo/handlers.go b/service_a/internal/domains/meteo/handlers.go
index 70862a1..1400be3 100644
--- a/service_a/internal/domains/meteo/handlers.go
+++ b/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) {