{# usage: {%- from 'bearing.jinja' import calc_bearing -%} {{- calc_bearing( lat, lon, option) -}} #}
{# Option Values: #}
{#  - 'D' output value Distance #}
{#  - 'B' output value bearing #}
{#  - 'C' output value compass direction like NW #}
{#  - 'T' output tekt of all three in format: 89.8 km E 93.8° #}

{%- macro calc_bearing(lat, lon, option) -%}
{%- set target_lat = lat | float %} 
{%- set target_lon = lon | float %} 
{%- set current_lat = state_attr('zone.home', 'latitude') | float %} 
{%- set current_lon = state_attr('zone.home', 'longitude') | float %}
{%- set rad = 0.017453292519943295 %} 
{%- set current_lat_rad= (current_lat * rad) | float %} 
{%- set current_lon_rad= (current_lon * rad) | float %} 
{%- set target_lat_rad= (target_lat * rad) | float %}
{%- set target_lon_rad= (target_lon * rad) | float %} 
{%- set delta_lat = (target_lat_rad - current_lat_rad) | float %}
{%- set delta_lon= (target_lon_rad - current_lon_rad) | float -%}
{%- set half_delta_lat = (delta_lat / 2.0) | float -%}
{%- set half_delta_lon = (delta_lon / 2.0) | float -%} 
{%- set sin_half_delta_lat = half_delta_lat | float | sin -%} 
{%- set sin_half_delta_lon = half_delta_lon | float | sin  -%} 
{%- set a = ((sin_half_delta_lat ** 2) + (cos(current_lat_rad) * cos(target_lat_rad) * (sin_half_delta_lon ** 2))) | float -%}
{%- set c = (2.0 * atan2(sqrt(a), sqrt(1.0 - a))) | float -%} 
{%- set dist = (c) * 6371.0 | float -%} 
{%- set y = (sin(delta_lon) | float) * (cos(target_lat_rad) | float) -%}
{%- set x = ( (cos(current_lat_rad) | float) * (sin(target_lat_rad) | float) - (sin(current_lat_rad) | float) * (cos(target_lat_rad) | float) * (cos(delta_lon) | float)) | float -%}
{%- set bearing = ((atan2(y, x) * 57.2957795) + 360.0) % 360.0 | float -%} 
{%- if bearing <= 22.5 %} {% set compass = 'N' -%}
{%- elif bearing <= 67.5 %} {% set compass = 'NE' -%}
{%- elif bearing <= 112.5 %} {% set compass = 'E' -%}
{%- elif bearing <= 157.5 %} {% set compass = 'SE' -%}
{%- elif bearing <= 202.5 %} {% set compass = 'S' -%}
{%- elif bearing <= 247.5 %} {% set compass = 'SW' -%}
{%- elif bearing <= 292.5 %} {% set compass = 'W' -%}
{%- elif bearing <= 337.5 %} {% set compass = 'NW' -%}
{%- else %} {% set compass = 'N' -%}  
{%- endif -%}
{%- if   option == 'D' -%} {{ dist | float(1) }}
{%- elif option == 'B' -%} {{ bearing | float(1) }} 
{%- elif option == 'C' -%} {{ bearing | float(1) }} 
{%- elif option == 'T' -%} {{- dist | round(2) }} km {{ compass }} {{ bearing | round(1) -}}° 
{%- else -%} error? 
{%- endif -%}
{%- endmacro -%}