feat(db): add endpoint to export influx data to csv

Assisted-by: Junie:claude-sonnet-4.6
Signed-off-by: Klagarge <remi@heredero.ch>

db/export-csv-loop.http

@@ -0,0 +1,49 @@
+@host = localhost:8080
+@username = user
+@password = password
+@from = 2026-05-27T14:00:00+02:00
+@to = 2026-05-27T18:00:00+02:00
+
+### Export CSV - Room A2 - loop over all nodes
+< {%
+  request.variables.set("nodesA2", [
+    {"room": "A2", "mac": "E1:C0:30:15:4E:89"},
+    {"room": "A2", "mac": "C6:7E:0A:DE:DA:74"},
+    {"room": "A2", "mac": "E8:F3:0A:F7:3B:F3"},
+    {"room": "A2", "mac": "C2:64:0F:68:35:3E"},
+    {"room": "A2", "mac": "F5:80:05:76:53:F0"},
+    {"room": "A2", "mac": "C6:95:1B:A6:49:E6"}
+  ])
+%}
+
+GET {{host}}/api/v1/export/csv?node={{$.nodesA2..mac}}&from={{from}}&to={{to}}
+Authorization: Basic {{username}} {{password}}
+
+> {%
+  let current = request.variables.get("nodesA2")[request.iteration()]
+  client.test(`Export CSV - Room ${current.room} - Node ${current.mac}`, () => {
+    client.assert(response.status === 200, `Expected 200, got ${response.status}`)
+  })
+%}
+
+### Export CSV - Room A3 - loop over all nodes
+< {%
+  request.variables.set("nodesA3", [
+    {"room": "A3", "mac": "ED:B2:F3:74:3E:C2"},
+    {"room": "A3", "mac": "CE:25:63:38:34:05"},
+    {"room": "A3", "mac": "E6:8A:79:C8:87:25"},
+    {"room": "A3", "mac": "DC:06:D9:40:7A:CB"},
+    {"room": "A3", "mac": "D5:2F:7E:30:10:5A"},
+    {"room": "A3", "mac": "EA:1A:AD:15:5E:9F"}
+  ])
+%}
+
+GET {{host}}/api/v1/export/csv?node={{$.nodesA3..mac}}&from={{from}}&to={{to}}
+Authorization: Basic {{username}} {{password}}
+
+> {%
+  let current = request.variables.get("nodesA3")[request.iteration()]
+  client.test(`Export CSV - Room ${current.room} - Node ${current.mac}`, () => {
+    client.assert(response.status === 200, `Expected 200, got ${response.status}`)
+  })
+%}

db/get-db.http

@@ -18,3 +18,10 @@ Authorization: Basic {{username}} {{password}}
 
 ### GET battery status of all devices
 GET {{host}}/api/v1/battery
+
+### Export sensor data as CSV for a node over a time range
+@node = C2:64:0F:68:35:3E
+@from = 2026-05-27T14:00:00+02:00
+@to = 2026-05-27T18:00:00+02:00
+GET {{host}}/api/v1/export/csv?node={{node}}&from={{from}}&to={{to}}
+Authorization: Basic {{username}} {{password}}

db/src/docs/docs.go

@@ -56,6 +56,72 @@ const docTemplate = `{
                 }
             }
         },
+        "/export/csv": {
+            "get": {
+                "security": [
+                    {
+                        "BasicAuth": []
+                    }
+                ],
+                "description": "Export CO2, temperature, humidity, window status and battery data for a node over a time range",
+                "produces": [
+                    "text/csv"
+                ],
+                "tags": [
+                    "export"
+                ],
+                "summary": "Export sensor data as CSV",
+                "parameters": [
+                    {
+                        "type": "string",
+                        "description": "Node MAC address (e.g. E8:F3:0A:F7:3B:F3)",
+                        "name": "node",
+                        "in": "query",
+                        "required": true
+                    },
+                    {
+                        "type": "string",
+                        "description": "Start time in RFC3339 format (e.g. 2026-05-27T13:00:00Z)",
+                        "name": "from",
+                        "in": "query",
+                        "required": true
+                    },
+                    {
+                        "type": "string",
+                        "description": "End time in RFC3339 format (e.g. 2026-05-27T15:00:00Z)",
+                        "name": "to",
+                        "in": "query",
+                        "required": true
+                    }
+                ],
+                "responses": {
+                    "200": {
+                        "description": "CSV file",
+                        "schema": {
+                            "type": "string"
+                        }
+                    },
+                    "400": {
+                        "description": "Bad Request",
+                        "schema": {
+                            "type": "object",
+                            "additionalProperties": {
+                                "type": "string"
+                            }
+                        }
+                    },
+                    "500": {
+                        "description": "Internal Server Error",
+                        "schema": {
+                            "type": "object",
+                            "additionalProperties": {
+                                "type": "string"
+                            }
+                        }
+                    }
+                }
+            }
+        },
         "/rooms": {
             "get": {
                 "security": [

db/src/docs/swagger.json

@@ -50,6 +50,72 @@
                 }
             }
         },
+        "/export/csv": {
+            "get": {
+                "security": [
+                    {
+                        "BasicAuth": []
+                    }
+                ],
+                "description": "Export CO2, temperature, humidity, window status and battery data for a node over a time range",
+                "produces": [
+                    "text/csv"
+                ],
+                "tags": [
+                    "export"
+                ],
+                "summary": "Export sensor data as CSV",
+                "parameters": [
+                    {
+                        "type": "string",
+                        "description": "Node MAC address (e.g. E8:F3:0A:F7:3B:F3)",
+                        "name": "node",
+                        "in": "query",
+                        "required": true
+                    },
+                    {
+                        "type": "string",
+                        "description": "Start time in RFC3339 format (e.g. 2026-05-27T13:00:00Z)",
+                        "name": "from",
+                        "in": "query",
+                        "required": true
+                    },
+                    {
+                        "type": "string",
+                        "description": "End time in RFC3339 format (e.g. 2026-05-27T15:00:00Z)",
+                        "name": "to",
+                        "in": "query",
+                        "required": true
+                    }
+                ],
+                "responses": {
+                    "200": {
+                        "description": "CSV file",
+                        "schema": {
+                            "type": "string"
+                        }
+                    },
+                    "400": {
+                        "description": "Bad Request",
+                        "schema": {
+                            "type": "object",
+                            "additionalProperties": {
+                                "type": "string"
+                            }
+                        }
+                    },
+                    "500": {
+                        "description": "Internal Server Error",
+                        "schema": {
+                            "type": "object",
+                            "additionalProperties": {
+                                "type": "string"
+                            }
+                        }
+                    }
+                }
+            }
+        },
         "/rooms": {
             "get": {
                 "security": [

db/src/docs/swagger.yaml

@@ -32,6 +32,50 @@ paths:
       summary: Get last battery level for each node
       tags:
       - battery
+  /export/csv:
+    get:
+      description: Export CO2, temperature, humidity, window status and battery data
+        for a node over a time range
+      parameters:
+      - description: Node MAC address (e.g. E8:F3:0A:F7:3B:F3)
+        in: query
+        name: node
+        required: true
+        type: string
+      - description: Start time in RFC3339 format (e.g. 2026-05-27T13:00:00Z)
+        in: query
+        name: from
+        required: true
+        type: string
+      - description: End time in RFC3339 format (e.g. 2026-05-27T15:00:00Z)
+        in: query
+        name: to
+        required: true
+        type: string
+      produces:
+      - text/csv
+      responses:
+        "200":
+          description: CSV file
+          schema:
+            type: string
+        "400":
+          description: Bad Request
+          schema:
+            additionalProperties:
+              type: string
+            type: object
+        "500":
+          description: Internal Server Error
+          schema:
+            additionalProperties:
+              type: string
+            type: object
+      security:
+      - BasicAuth: []
+      summary: Export sensor data as CSV
+      tags:
+      - export
   /rooms:
     get:
       description: Get a list of all unique rooms from the measurement

db/src/rest/rest.go

@@ -2,13 +2,16 @@ package rest
 
 import (
 	"context"
+	"encoding/csv"
 	"fmt"
 	_ "gateway/docs"
 	"gateway/influx"
 	"net/http"
 	"regexp"
 	"slices"
+	"strconv"
 	"strings"
+	"time"
 
 	"github.com/gin-contrib/cors"
 	"github.com/gin-gonic/gin"
@@ -77,6 +80,7 @@ func (g *RestGateway) setupRoutes() {
 		v1.GET("/rooms", g.getRooms)
 		v1.GET("/rooms/:room-id/current", g.getRoomCurrent)
 		v1.GET("/rooms/:room-id/history", g.getRoomHistory)
+		v1.GET("/export/csv", g.getExportCSV)
 	}
 
 	g.engine.GET("/swagger/*any", ginSwagger.WrapHandler(swaggerFiles.Handler))
@@ -162,6 +166,121 @@ func (g *RestGateway) getBattery(c *gin.Context) {
 	c.JSON(http.StatusOK, result)
 }
 
+// This function is 100% AI generated with Junie (Claude Sonnet 4.6)
+// GET /api/v1/export/csv
+// getExportCSV godoc
+// @Summary Export sensor data as CSV
+// @Description Export CO2, temperature, humidity, window status and battery data for a node over a time range
+// @Tags export
+// @Produce text/csv
+// @Param node query string true "Node MAC address (e.g. E8:F3:0A:F7:3B:F3)"
+// @Param from query string true "Start time in RFC3339 format (e.g. 2026-05-27T13:00:00Z)"
+// @Param to query string true "End time in RFC3339 format (e.g. 2026-05-27T15:00:00Z)"
+// @Success 200 {string} string "CSV file"
+// @Failure 400 {object} map[string]string
+// @Failure 500 {object} map[string]string
+// @Security BasicAuth
+// @Router /export/csv [get]
+func (g *RestGateway) getExportCSV(c *gin.Context) {
+	node := c.Query("node")
+	from := c.Query("from")
+	to := c.Query("to")
+
+	if node == "" || from == "" || to == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "node, from and to query parameters are required"})
+		return
+	}
+
+	if _, err := time.Parse(time.RFC3339, from); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "from must be a valid RFC3339 timestamp"})
+		return
+	}
+	if _, err := time.Parse(time.RFC3339, to); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "to must be a valid RFC3339 timestamp"})
+		return
+	}
+
+	query := fmt.Sprintf(
+		`SELECT time, co2_ppm, temp, battery, humidity, window_open FROM "%s" WHERE time >= '%s' AND time <= '%s' AND "node" = '%s' ORDER BY time ASC`,
+		g.measurementName, from, to, node,
+	)
+
+	it, err := g.influxGateway.Query(context.Background(), query)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.Header("Content-Disposition", fmt.Sprintf(`attachment; filename="export-%s.csv"`, strings.ReplaceAll(node, ":", "_")))
+	c.Header("Content-Type", "text/csv")
+
+	w := csv.NewWriter(c.Writer)
+	_ = w.Write([]string{"time", "co2", "temperature", "humidity", "windows", "battery"})
+
+	for it.Next() {
+		row := it.Value()
+
+		var tsStr string
+		if t, ok := row["time"]; ok {
+			var tt time.Time
+			switch v := t.(type) {
+			case time.Time:
+				tt = v
+			case int64:
+				tt = time.Unix(0, v)
+			}
+			loc := time.FixedZone("UTC+2", 2*60*60)
+			tsStr = tt.In(loc).Format("2006-01-02T15:04:05")
+		}
+
+		co2 := formatField(row["co2_ppm"])
+		temp := formatField(row["temp"])
+		humidity := formatField(row["humidity"])
+		windowOpen := formatField(row["window_open"])
+		battery := formatField(row["battery"])
+
+		_ = w.Write([]string{
+			tsStr,
+			co2,
+			temp,
+			humidity,
+			windowOpen,
+			battery,
+		})
+	}
+
+	if err := it.Err(); err != nil {
+		// Headers already sent; best effort
+		_ = w.Write([]string{"error", err.Error()})
+	}
+
+	w.Flush()
+}
+
+// formatField converts an any value to its string representation for CSV output.
+func formatField(v any) string {
+	if v == nil {
+		return ""
+	}
+	switch val := v.(type) {
+	case float64:
+		return strconv.FormatFloat(val, 'f', -1, 64)
+	case float32:
+		return strconv.FormatFloat(float64(val), 'f', -1, 32)
+	case int64:
+		return strconv.FormatInt(val, 10)
+	case int32:
+		return strconv.FormatInt(int64(val), 10)
+	case bool:
+		if val {
+			return "1"
+		}
+		return "0"
+	default:
+		return fmt.Sprintf("%v", v)
+	}
+}
+
 func (g *RestGateway) Run(addr string) error {
 	return g.engine.Run(addr)
 }