Chart is not updating after callback with radioItem!

Dash Python
1

Hi everyone. I am new to python, I want to create dashboards. I have some HTML/CSS experience so that helps but I am still very confused on callbacks and what/what not to put on Output/Input and the following function + the data it should return.

What I want:
I essentially want one main chart, and based off the radioItem a person selects (BTC or ETH) the main chart will update based on price from the past year. Eventually, I’d like to add more charts, newsfeeds etc that updates as well based off the currency selected in the radioItem.

I took a crack at it, here is my code:

Edited: updated code

import dash_core_components as dcc 
import dash_html_components as html 
import plotly.graph_objs as go
from dash.dependencies import Input, Output 
import pandas as pd 
import numpy as np

app = dash.Dash()

btc_data = pd.read_csv('BTC-CAD.csv', parse_dates=True)

app.layout = html.Div([
    
    html.H1('Test'),
    
    html.Div([
        dcc.RadioItems(
            id='radio-1',
            options=[
                {'label': 'Bitcoin', 'value': 'BTC'},
                {'label': 'Ethereum', 'value': 'ETC'},
            ], 
            value='BTC'
        )
    ], style={'width': '48%', 'display': 'inline-block'}
    ),
    
    html.Div([
        dcc.Graph(
            id = 'scatter-chart-1',
                figure = {
                    'data' : [
                        go.Scatter(
                            x = btc_data.Date,
                            y = btc_data.Close,
                            mode = 'lines'
                )
            ],
        'layout': go.Layout(
            title = 'BTC - CAD Prices',
            xaxis = {'title' : 'Date'},
            yaxis = {'title' : 'Price (Cad)'}
            )
        }
    )
    ])
])

# call back to update main graph 
@app.callback(
    dash.dependencies.Output('scatter-chart-1', 'figure'),
    [dash.dependencies.Input('radio-1', 'value')])
def update_page(radio):
    
    eth_data = pd.read_csv('ETH-CAD.csv', parse_dates=True) 

    if value == 'BTC':
        figure = {
            'data' : [
                go.Scatter(
                    x = btc_data.Date,
                    y = btc_data.Close,
                    mode = 'lines'
                )
            ],
            'layout': go.Layout(
            title = 'BTC - CAD Prices',
            xaxis = {'title' : 'Date'},
            yaxis = {'title' : 'Price (Cad)'}
            )
        }
    return figure 
    
    if value == 'ETH':
        figure = {
            'data': [
                go.Scatter(
                    x = eth_data.Date,
                    y = eth_data.Close,
                    mode = 'lines'
                )
            ]
        }
    return figure 
        

if __name__ == '__main__':
    app.run_server(port=4050)```


any help is appreciated!