"""FilePicker for streamlit. 
Still doesn't seem to be a good solution for a way to select files to process from the server Streamlit is running on.
Here's a pretty functional solution. 
Usage:
```
import streamlit as st
from filepicker import st_file_selector
tif_file = st_file_selector(st, key = 'tif', label = 'Choose tif file')
```
"""

import os
import streamlit as st

def update_dir(key):
    choice = st.session_state[key]
    if os.path.isdir(os.path.join(st.session_state[key+'curr_dir'], choice)):
        st.session_state[key+'curr_dir'] = os.path.normpath(os.path.join(st.session_state[key+'curr_dir'], choice))
        files = sorted(os.listdir(st.session_state[key+'curr_dir']))
        if "images" in files:
          files.remove("images")
        st.session_state[key+'files'] = files

def st_file_selector(st_placeholder, path='.', label='Select a file/folder', key = 'selected'):
    if key+'curr_dir' not in st.session_state:
        base_path = '.' if path is None or path == '' else path
        base_path = base_path if os.path.isdir(base_path) else os.path.dirname(base_path)
        base_path = '.' if base_path is None or base_path == '' else base_path

        files = sorted(os.listdir(base_path))
        files.insert(0, 'Choose a file...')
        if "images" in files:
          files.remove("images")
        st.session_state[key+'files'] = files
        st.session_state[key+'curr_dir'] = base_path
    else:
        base_path = st.session_state[key+'curr_dir']

    selected_file = st_placeholder.selectbox(label=label, 
                                        options=st.session_state[key+'files'], 
                                        key=key, 
                                        on_change = lambda: update_dir(key))
    
    if selected_file == "Choose a file...":
        return None

    return selected_file