first version

tracker/views.py

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+from datetime import timedelta
+from typing import Optional
+
+from django.contrib import messages
+from django.contrib.admin.views.decorators import staff_member_required
+from django.shortcuts import redirect, render
+from django.urls import reverse
+from django.utils import timezone
+from django.utils.dateparse import parse_date
+
+from tracker.api import build_day, pulse_trend
+from tracker.models import DoseLog, PulseReading, ScheduledDose
+
+CHART_WIDTH = 320
+CHART_HEIGHT = 140
+CHART_PADDING = 24
+
+
+def build_chart(readings: list[PulseReading]) -> Optional[dict]:
+    """Lay the readings out as SVG coordinates, so the page needs no JavaScript."""
+    if len(readings) < 2:
+        return None
+
+    bpms = [r.bpm for r in readings]
+    low, high = min(bpms), max(bpms)
+    # A flat line would divide by zero, and a narrow range exaggerates noise.
+    span = max(high - low, 10)
+    mid = (high + low) / 2
+    low, high = mid - span / 2, mid + span / 2
+
+    first_day = readings[0].date
+    total_days = max((readings[-1].date - first_day).days, 1)
+
+    inner_width = CHART_WIDTH - 2 * CHART_PADDING
+    inner_height = CHART_HEIGHT - 2 * CHART_PADDING
+
+    points = []
+    for reading in readings:
+        x = CHART_PADDING + (reading.date - first_day).days / total_days * inner_width
+        y = CHART_PADDING + (high - reading.bpm) / (high - low) * inner_height
+        points.append({"x": round(x, 1), "y": round(y, 1), "reading": reading})
+
+    return {
+        "points": points,
+        "polyline": " ".join(f"{p['x']},{p['y']}" for p in points),
+        "low": round(low),
+        "high": round(high),
+        "average": round(sum(bpms) / len(bpms), 1),
+        "trend": pulse_trend(readings),
+        "width": CHART_WIDTH,
+        "height": CHART_HEIGHT,
+        "first_date": first_day,
+        "last_date": readings[-1].date,
+    }
+
+
+@staff_member_required
+def today(request):
+    """The main screen: tick off the day's doses and record the pulse."""
+    day = parse_date(request.GET.get("date", "")) or timezone.localdate()
+
+    if request.method == "POST":
+        day = parse_date(request.POST.get("date", "")) or timezone.localdate()
+        doses = ScheduledDose.objects.filter(is_active=True, medication__is_active=True)
+
+        for dose in doses:
+            taken = f"dose-{dose.id}" in request.POST
+            log, _ = DoseLog.objects.get_or_create(
+                scheduled_dose=dose, date=day, defaults={"taken": taken}
+            )
+            log.taken = taken
+            log.save()
+
+        bpm = (request.POST.get("bpm") or "").strip()
+        if bpm:
+            try:
+                PulseReading.objects.update_or_create(
+                    date=day, defaults={"bpm": int(bpm)}
+                )
+            except ValueError:
+                messages.error(request, f"'{bpm}' is not a valid pulse.")
+        else:
+            # Clearing the field removes the reading for that day.
+            PulseReading.objects.filter(date=day).delete()
+
+        messages.success(request, f"Saved for {day:%A %d %B}.")
+        return redirect(f"{reverse('tracker:today')}?date={day.isoformat()}")
+
+    readings = list(
+        PulseReading.objects.filter(
+            date__gte=timezone.localdate() - timedelta(days=90)
+        ).order_by("date")
+    )
+
+    return render(
+        request,
+        "tracker/today.html",
+        {
+            "title": "Today",
+            "day": build_day(day),
+            "is_today": day == timezone.localdate(),
+            "previous_date": day - timedelta(days=1),
+            "next_date": day + timedelta(days=1),
+            "chart": build_chart(readings),
+            "reading_count": len(readings),
+        },
+    )