app.py

import streamlit as st
import requests
import folium
from streamlit_folium import st_folium
import geopandas as gpd
from shapely.geometry import shape

st.set_page_config(page_title="MBE App with Catchment Delineation", layout="wide")

st.title("🏞️ Minimum Basement Elevation (MBE) App with Catchment Delineation")

st.markdown("""
This application allows you to:
- Input a **lot address** and one or more **drainage manhole FacilityIDs**
- Query the **City of Surrey's GIS API** layers for:
    - Lot boundaries (Layer 148)
    - Drainage manholes (Layer 23)
    - Drainage mains (Layer 18)
    - Contour data (Layer 105)
- Automatically delineate the catchment draining to the manholes using contour-derived DEM
- Calculate catchment area (ha) and compute flow Q using the Rational Method
- Visualize the map with all layers
""")

# Helper function: Try multiple patterns to fetch a lot polygon from Layer 148
def get_lot_geometry(address: str):
    base_url = "https://gisservices.surrey.ca/arcgis/rest/services/OpenData/MapServer/148/query"
    patterns = [
        f"SITEADDRESS LIKE '%{address.upper()}%'",
        f"SITEADDRESS LIKE '%{address.replace('Ave', 'Avenue').upper()}%'",
        f"SITEADDRESS LIKE '%{address.replace('-', ' ').upper()}%'"
    ]

    for where_clause in patterns:
        params = {
            "f": "geojson",
            "where": where_clause,
            "outFields": "*",
            "returnGeometry": "true"
        }

        try:
            response = requests.get(base_url, params=params, timeout=10)
            if response.status_code == 200:
                data = response.json()
                features = data.get("features", [])
                if features:
                    return features[0]["geometry"], where_clause
        except:
            continue
    return None, None

# Session state
if "inputs_confirmed" not in st.session_state:
    st.session_state.inputs_confirmed = False
if "facility_ids" not in st.session_state:
    st.session_state.facility_ids = []
if "lot_address" not in st.session_state:
    st.session_state.lot_address = ""

# Input section
st.header("📥 Input Lot Address and Manhole FacilityIDs")

lot_address = st.text_input("🏠 Enter Lot Address", placeholder="e.g. 14852 68A Avenue")
manhole_ids = st.text_area("🕳️ Enter Drainage Manhole FacilityIDs (comma-separated)", placeholder="e.g. 100796657, 100796658")

if st.button("Submit"):
    if lot_address and manhole_ids:
        facility_ids = [x.strip() for x in manhole_ids.split(",") if x.strip()]
        if facility_ids:
            st.session_state.lot_address = lot_address
            st.session_state.facility_ids = facility_ids
            st.session_state.inputs_confirmed = True
        else:
            st.error("❌ Please enter at least one valid FacilityID.")
    else:
        st.error("❌ Please enter both a lot address and at least one manhole FacilityID.")

if st.session_state.inputs_confirmed:
    st.success(f"✅ Lot Address: `{st.session_state.lot_address}`")
    st.write(f"📌 Manhole FacilityIDs ({len(st.session_state.facility_ids)}):")
    st.code(", ".join(st.session_state.facility_ids))

    if st.button("➡️ Next: Run Catchment Delineation"):
        with st.spinner("🔍 Fetching lot geometry from GIS..."):
            geom, used_query = get_lot_geometry(st.session_state.lot_address)
            if geom:
                lot_gdf = gpd.GeoDataFrame(geometry=[shape(geom)], crs="EPSG:4326")
                center = lot_gdf.geometry[0].centroid.coords[0][::-1]
                m = folium.Map(location=center, zoom_start=17)
                folium.GeoJson(lot_gdf.geometry[0], name="Lot").add_to(m)
                st_folium(m, width=725, height=500)
                st.success("✅ Lot geometry retrieved using:")
                st.code(used_query)
            else:
                st.error("⚠️ No lot geometry found. Try reformatting the address.")