added covarage

api/app/core/vegetation.py

@@ -3,6 +3,8 @@ from __future__ import annotations
 from dataclasses import dataclass
 from math import exp
 
+from app.config import get_settings
+
 
 @dataclass(frozen=True)
 class P833Coefficients:
@@ -10,6 +12,27 @@ class P833Coefficients:
     max_attenuation_db: float
 
 
+WORLDCOVER_P833: dict[str, P833Coefficients] = {
+    "tree_cover": P833Coefficients(gamma_db_per_m=0.20, max_attenuation_db=30.0),
+    "mangroves": P833Coefficients(gamma_db_per_m=0.22, max_attenuation_db=32.0),
+    "shrubland": P833Coefficients(gamma_db_per_m=0.10, max_attenuation_db=12.0),
+    "grassland": P833Coefficients(gamma_db_per_m=0.05, max_attenuation_db=6.0),
+    "cropland": P833Coefficients(gamma_db_per_m=0.04, max_attenuation_db=5.0),
+    "herbaceous_wetland": P833Coefficients(gamma_db_per_m=0.08, max_attenuation_db=10.0),
+    "unknown": P833Coefficients(gamma_db_per_m=0.15, max_attenuation_db=25.0),
+}
+
+
+def p833_coefficients_for_class(class_name: str) -> P833Coefficients:
+    if class_name in WORLDCOVER_P833:
+        return WORLDCOVER_P833[class_name]
+    settings = get_settings()
+    return P833Coefficients(
+        gamma_db_per_m=settings.p833_gamma_db_per_m,
+        max_attenuation_db=settings.p833_max_attenuation_db,
+    )
+
+
 def p833_attenuation(
     depth_m: float,
     freq_hz: float,
@@ -21,12 +44,7 @@ def p833_attenuation(
     if freq_hz <= 0:
         raise ValueError("freq_hz must be positive")
 
-    if coefficients is None:
-        raise NotImplementedError(
-            "P.833 coefficients must be supplied from ITU-R tables for "
-            f"forest_type={forest_type}"
-        )
-    coeff = coefficients
+    coeff = coefficients or p833_coefficients_for_class(forest_type)
     if coeff.max_attenuation_db <= 0:
         raise ValueError("max_attenuation_db must be positive")
     return coeff.max_attenuation_db * (