import streamlit as st
import folium
from streamlit_folium import folium_static
import requests
from PIL import Image
import io
from datetime import datetime, timedelta
import imageio

# Constants
WMS_URL = "https://wms.geo.admin.ch/"
LAYER_NAME = "ch.swisstopo.zeitreihen"

def get_wms_image(bbox, width, height, time):
    params = {
        'SERVICE': 'WMS',
        'VERSION': '1.3.0',
        'REQUEST': 'GetMap',
        'LAYERS': LAYER_NAME,
        'STYLES': '',
        'CRS': 'EPSG:4326',
        'BBOX': ','.join(map(str, bbox)),
        'WIDTH': width,
        'HEIGHT': height,
        'FORMAT': 'image/png',
        'TIME': time.strftime('%Y-%m-%d')
    }
    response = requests.get(WMS_URL, params=params)
    return Image.open(io.BytesIO(response.content))

def create_animation(bbox, width, height, start_date, end_date, step):
    images = []
    current_date = start_date
    while current_date <= end_date:
        img = get_wms_image(bbox, width, height, current_date)
        images.append(img)
        current_date += step
    return images

# Streamlit app
st.title("Swisstopo Historical Animation Generator")

# Sidebar for input parameters
st.sidebar.header("Input Parameters")
start_year = st.sidebar.number_input("Start Year", min_value=1850, max_value=2022, value=1900)
end_year = st.sidebar.number_input("End Year", min_value=1850, max_value=2022, value=2022)
step_years = st.sidebar.number_input("Step (years)", min_value=1, max_value=50, value=10)

# Main content
st.subheader("Select Area of Interest")
m = folium.Map(location=[46.8, 8.2], zoom_start=8)
folium_static(m)

if st.button("Generate Animation"):
    # Get bounding box from the map
    bounds = m.get_bounds()
    bbox = [bounds['_southWest']['lng'], bounds['_southWest']['lat'],
            bounds['_northEast']['lng'], bounds['_northEast']['lat']]

    width, height = 800, 600  # Image dimensions
    start_date = datetime(start_year, 1, 1)
    end_date = datetime(end_year, 12, 31)
    step = timedelta(days=step_years * 365)

    with st.spinner("Generating animation..."):
        images = create_animation(bbox, width, height, start_date, end_date, step)
        
        # Save as GIF
        output_file = "historical_animation.gif"
        imageio.mimsave(output_file, images, duration=1)  # 1 second per frame
        
        st.success(f"Animation generated and saved as {output_file}")
        st.image(output_file)

st.sidebar.info("This application generates historical animations using Swisstopo's WMS. Select the area of interest on the map, set the time range and step, then click 'Generate Animation'.")