import os
import hashlib
from flask import Flask, render_template, request, redirect, flash, url_for
from werkzeug.middleware.proxy_fix import ProxyFix

app = Flask(__name__)
app.secret_key = os.getenv("SECRET_KEY")
BASE_URL = os.getenv("BASE_URL")  # Adjust as appropriate for your deployment

app.wsgi_app = ProxyFix(
    app.wsgi_app, x_for=1, x_proto=1, x_host=1, x_prefix=1
)

UPLOAD_FOLDER = os.getenv("UPLOAD_FOLDER")
os.makedirs(UPLOAD_FOLDER, exist_ok=True)

ALLOWED_EXTENSIONS = {'txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'}

def allowed_file(filename):
    return '.' in filename and filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS

def get_file_hash(file_storage):
    file_storage.seek(0)
    sha = hashlib.sha256()
    while True:
        chunk = file_storage.read(4096)
        if not chunk:
            break
        sha.update(chunk)
    hash8 = sha.hexdigest()[:8]
    file_storage.seek(0)
    return hash8

@app.route('/', methods=['GET', 'POST'])
def upload_file():
    uploaded_url = None
    if request.method == 'POST':
        if 'file' not in request.files:
            flash('No file part', 'error')
            return redirect(request.url)
        file = request.files['file']
        if file.filename == '':
            flash('No selected file', 'error')
            return redirect(request.url)
        if file and allowed_file(file.filename):
            hash8 = get_file_hash(file)
            ext = file.filename.rsplit('.', 1)[1].lower()
            filename = f"{hash8}.{ext}"
            filepath = os.path.join(UPLOAD_FOLDER, filename)
            file.save(filepath)
            # Compose the URL (assuming files will eventually be hosted at /uploads/<filename>)
            uploaded_url = f"{BASE_URL}/{filename}"
            return render_template("index.html", uploaded_url=uploaded_url)
        else:
            flash('Invalid file extension', 'error')
            return redirect(request.url)
    return render_template("index.html", uploaded_url=uploaded_url)

if __name__ == '__main__':
    app.run(debug=True)