refactor getValue for new filter/limit structs

internal/api/http.go

@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
-	"time"
 
 	"log/slog"
 
@@ -189,32 +188,25 @@ func apiV1GetValues(db *db.TelemDb) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		var err error
 
+		bef, err := extractBusEventFilter(r)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		lim, err := extractLimitModifier(r)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
 		// we need a start and end time. If none is provided,
 		// we use unix epoch as start, and now + 1 day as end.
-		start := time.Unix(0, 0)
-		startString := r.URL.Query().Get("start")
-		if startString != "" {
-			start, err = time.Parse(time.RFC3339, startString)
-			if err != nil {
-				http.Error(w, "error getting values", http.StatusInternalServerError)
-				return
-			}
-		}
-		end := time.Now().Add(1 * time.Hour)
-		endParam := r.URL.Query().Get("start")
-		if endParam != "" {
-			end, err = time.Parse(time.RFC3339, endParam)
-			if err != nil {
-				http.Error(w, "error getting values", http.StatusInternalServerError)
-				return
-			}
-		}
 		name := chi.URLParam(r, "name")
 		field := chi.URLParam(r, "field")
 
-		// TODO: add limit and pagination
+		// override the bus event filter name option
+		bef.Names = []string{name}
 
-		res, err := db.GetValues(r.Context(), name, field, start, end)
+		res, err := db.GetValues(r.Context(), *bef, field, lim)
 		if err != nil {
 			// 500 server error:
 			http.Error(w, "error getting values", http.StatusInternalServerError)

internal/db/getters.go

@@ -2,6 +2,7 @@ package db
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -104,7 +105,6 @@ func (tdb *TelemDb) GetPackets(ctx context.Context, filter BusEventFilter, optio
 	return events, err
 }
 
-
 // We now need a different use-case: we would like to extract a value from
 // a specific packet.
 
@@ -118,17 +118,37 @@ type Datum struct {
 // GetValues queries the database for values in a given time range.
 // A value is a specific data point. For example, bms_measurement.current
 // would be a value.
-func (tdb *TelemDb) GetValues(ctx context.Context, packetName, field string, start time.Time,
-	end time.Time) ([]Datum, error) {
+func (tdb *TelemDb) GetValues(ctx context.Context, bef BusEventFilter,
+	field string, opts ...Modifier) ([]Datum, error) {
 	// this fragment uses json_extract from sqlite to get a single
 	// nested value.
-	SqlFrag := `
-	SELECT 
-	ts as timestamp,
-	json_extract(data, '$.' || ?) as val
-	FROM bus_events WHERE name IS ? 
-	`
-	rows, err := tdb.db.QueryxContext(ctx, SqlFrag, field, packetName)
+	sb := strings.Builder{}
+	sb.WriteString(`SELECT ts as timestamp, json_extract(data, '$.' || ?) as val FROM bus_events WHERE `)
+	if len(bef.Names) != 1 {
+		return nil, errors.New("invalid number of names")
+	}
+
+	qStrings := []string{"name is ?"}
+	// add timestamp limit.
+	if !bef.TimerangeStart.IsZero() {
+		qString := fmt.Sprintf("ts >= %d", bef.TimerangeStart.UnixMilli())
+		qStrings = append(qStrings, qString)
+	}
+
+	if !bef.TimerangeEnd.IsZero() {
+		qString := fmt.Sprintf("ts <= %d", bef.TimerangeEnd.UnixMilli())
+		qStrings = append(qStrings, qString)
+	}
+	// join qstrings with AND
+	sb.WriteString(strings.Join(qStrings, " AND "))
+
+	for _, m := range opts {
+		if m == nil {
+			continue
+		}
+		m.ModifyStatement(&sb)
+	}
+	rows, err := tdb.db.QueryxContext(ctx, sb.String(), field, bef.Names[0])
 	if err != nil {
 		return nil, err
 	}
@@ -136,7 +156,10 @@ func (tdb *TelemDb) GetValues(ctx context.Context, packetName, field string, sta
 	data := make([]Datum, 0, 10)
 	for rows.Next() {
 		var d Datum = Datum{}
-		err = rows.StructScan(&d)
+		var ts int64
+		err = rows.Scan(&ts, &d.Value)
+		d.Timestamp = time.UnixMilli(ts)
+
 		if err != nil {
 			fmt.Print(err)
 			return data, err