"""
Streamlit File Extension Renamer
--------------------------------
Lightweight Streamlit app for Hugging Face Spaces.

Updates (2025‑05‑22):
* Ensures Streamlit has a writable config dir (`STREAMLIT_HOME`) inside container.
* Sets a fallback `HOME` env so `~/.streamlit` resolves safely.
* Compatible with Streamlit >=1.45.1 (bug‑fixed event‑loop).
"""
from __future__ import annotations

import os
import pathlib
import io
import zipfile
from datetime import datetime
from pathlib import Path

# ---------------------------------------------------------------------
# Environment hardening (MUST run before `import streamlit`)
# ---------------------------------------------------------------------
os.environ.setdefault("STREAMLIT_HOME", "/tmp/.streamlit")
os.environ.setdefault("HOME", "/tmp")
pathlib.Path(os.environ["STREAMLIT_HOME"]).mkdir(parents=True, exist_ok=True)

import streamlit as st

# ---------------------------------------------------------------------
# Configuration
# ---------------------------------------------------------------------
ALLOWED_TARGET_EXTS: list[str] = [
    ".txt", ".pdf", ".doc", ".docx", ".json", ".csv", ".xml", ".html",
    ".css", ".js", ".md", ".jpg", ".jpeg", ".png", ".gif", ".bmp", ".tiff",
    ".svg", ".ico", ".mp3", ".wav", ".mp4", ".avi", ".mkv", ".mov",
    ".zip", ".tar", ".gz", ".7z",
]

DISALLOWED_SOURCE_EXTS: set[str] = {".exe", ".bin"}

# ---------------------------------------------------------------------
# UI helpers
# ---------------------------------------------------------------------

def make_sidebar() -> str:
    st.sidebar.header("Settings")
    target_ext = st.sidebar.selectbox(
        "Target extension (applied to **all** uploaded files)",
        options=ALLOWED_TARGET_EXTS,
        index=ALLOWED_TARGET_EXTS.index(".pdf"),
    )
    st.sidebar.markdown(
        "❗ **Note**: This tool only renames file extensions. It does **not** "
        "convert the underlying format."
    )
    return target_ext


def make_uploader():
    return st.file_uploader(
        "Upload one or more files",
        accept_multiple_files=True,
        type=[ext.lstrip(".") for ext in ALLOWED_TARGET_EXTS],
        help="Drag‑and‑drop or browse for files to rename.",
    )

# ---------------------------------------------------------------------
# Core logic
# ---------------------------------------------------------------------

def write_zip(uploaded_files: list[st.runtime.uploaded_file_manager.UploadedFile],
              target_ext: str) -> io.BytesIO:
    buffer = io.BytesIO()
    with zipfile.ZipFile(buffer, "w", zipfile.ZIP_DEFLATED) as zf:
        for file in uploaded_files:
            orig_path = Path(file.name)
            if orig_path.suffix.lower() in DISALLOWED_SOURCE_EXTS:
                st.warning(f"⏭️  Skipping disallowed file: **{orig_path.name}**")
                continue
            renamed = orig_path.with_suffix(target_ext)
            zf.writestr(renamed.name, file.read())
            st.success(f"✅ Renamed **{orig_path.name}** → **{renamed.name}**")
    buffer.seek(0)
    return buffer

# ---------------------------------------------------------------------
# Main
# ---------------------------------------------------------------------

def main() -> None:
    st.set_page_config("Extension Renamer", page_icon="📄", layout="centered")
    st.title("📄 Universal File‑Extension Renamer")
    st.write("Upload files, choose a new extension, and download them renamed "
             "in a ZIP archive.")

    target_ext = make_sidebar()
    uploaded_files = make_uploader()

    if uploaded_files and st.button("🔄 Rename & Package"):
        zip_buffer = write_zip(uploaded_files, target_ext)
        timestamp = datetime.utcnow().strftime("%Y%m%dT%H%M%SZ")
        st.download_button(
            label="⬇️ Download ZIP",
            data=zip_buffer,
            file_name=f"renamed_{timestamp}.zip",
            mime="application/zip",
        )

    st.caption("© 2025 File‑Extension Renamer • Streamlit • Hugging Face Spaces")

if __name__ == "__main__":
    main()