import io
import panel as pn
import pandas as pd
import hvplot.pandas

pn.extension(template='fast')

pn.state.template.title = 'hvPlot Explorer'

upload = pn.widgets.FileInput(name='Upload file', height=50)
select = pn.widgets.Select(options={
    'Penguins': 'https://raw.githubusercontent.com/mwaskom/seaborn-data/master/penguins.csv',
    'Diamonds': 'https://raw.githubusercontent.com/mwaskom/seaborn-data/master/diamonds.csv',
    'Titanic': 'https://raw.githubusercontent.com/mwaskom/seaborn-data/master/titanic.csv',
    'MPG': 'https://raw.githubusercontent.com/mwaskom/seaborn-data/master/mpg.csv'
})

def add_data(event):
    b = io.BytesIO()
    upload.save(b)
    b.seek(0)
    name = '.'.join(upload.filename.split('.')[:-1])
    select.options[name] = b
    select.param.trigger('options')
    select.value = b
    
upload.param.watch(add_data, 'filename')

def explore(csv):
    df = pd.read_csv(csv)
    explorer = hvplot.explorer(df)
    def plot_code(**kwargs):
        code = f'```python\n{explorer.plot_code()}\n```'
        return pn.pane.Markdown(code, sizing_mode='stretch_width')
    return pn.Column(
        explorer,
        '**Code**:',
        pn.bind(plot_code, **explorer.param.objects())
    )

widgets = pn.Column(
    "Select an existing dataset or upload one of your own CSV files and start exploring your data.",
    pn.Row(
        select,
        upload,
    )
).servable()  

output = pn.panel(pn.bind(explore, select)).servable()

pn.Column(widgets, output)