fix

backend/app/services/intervals.py

@@ -0,0 +1,88 @@
+import numpy as np
+
+from backend.app.models.activity import DataPoint, Interval
+
+
+def detect_intervals(
+    data_points: list[DataPoint],
+    ftp: float | None = None,
+    min_duration: int = 30,
+) -> list[Interval]:
+    """
+    Auto-detect work/rest intervals based on power thresholds.
+    Work = power >= 88% FTP (sweetspot and above)
+    Rest = power < 55% FTP (active recovery)
+    """
+    powers = [dp.power for dp in data_points]
+    if not any(p is not None for p in powers):
+        return []
+
+    if not ftp or ftp <= 0:
+        # Without FTP, use median power as threshold
+        valid_powers = [p for p in powers if p is not None and p > 0]
+        if not valid_powers:
+            return []
+        threshold_high = np.median(valid_powers) * 1.15
+        threshold_low = np.median(valid_powers) * 0.65
+    else:
+        threshold_high = ftp * 0.88
+        threshold_low = ftp * 0.55
+
+    intervals: list[Interval] = []
+    current_type: str | None = None
+    start_idx: int = 0
+
+    for i, dp in enumerate(data_points):
+        p = dp.power if dp.power is not None else 0
+        if p >= threshold_high:
+            new_type = "work"
+        elif p < threshold_low:
+            new_type = "rest"
+        else:
+            continue  # tempo zone — don't break interval
+
+        if current_type is None:
+            current_type = new_type
+            start_idx = i
+        elif new_type != current_type:
+            interval = _build_interval(data_points, start_idx, i - 1, current_type, min_duration)
+            if interval:
+                intervals.append(interval)
+            current_type = new_type
+            start_idx = i
+
+    # Close last interval
+    if current_type is not None:
+        interval = _build_interval(data_points, start_idx, len(data_points) - 1, current_type, min_duration)
+        if interval:
+            intervals.append(interval)
+
+    return intervals
+
+
+def _build_interval(
+    data_points: list[DataPoint],
+    start_idx: int,
+    end_idx: int,
+    interval_type: str,
+    min_duration: int,
+) -> Interval | None:
+    segment = data_points[start_idx:end_idx + 1]
+    if len(segment) < min_duration:
+        return None
+
+    powers = [dp.power for dp in segment if dp.power is not None]
+    hrs = [dp.heart_rate for dp in segment if dp.heart_rate is not None]
+
+    duration = int((segment[-1].timestamp - segment[0].timestamp).total_seconds())
+    if duration < min_duration:
+        return None
+
+    return Interval(
+        start_ts=segment[0].timestamp,
+        end_ts=segment[-1].timestamp,
+        interval_type=interval_type,
+        avg_power=round(sum(powers) / len(powers), 1) if powers else None,
+        avg_hr=round(sum(hrs) / len(hrs)) if hrs else None,
+        duration=duration,
+    )