#!/usr/bin/env python3
"""Private loopback demo server for the Grade 3 curriculum showcase."""

import argparse
import json
import mimetypes
import os
import re
import sys
import zipfile
from http import HTTPStatus
from http.server import SimpleHTTPRequestHandler, ThreadingHTTPServer
from pathlib import Path
from urllib.parse import unquote, urlparse

ROOT = Path(__file__).resolve().parent
DEFAULT_DOWNLOADS = Path.home() / 'Downloads' / 'CoreKnowledge_Grades_1-5_EN_ES'
sys.path.insert(0, str(ROOT / 'src'))
from server_catalog import lookup_material, material_index


class ShowcaseHandler(SimpleHTTPRequestHandler):
    def __init__(self, *args, downloads_dir=None, **kwargs):
        self.downloads_dir = Path(downloads_dir or DEFAULT_DOWNLOADS).resolve()
        super().__init__(*args, directory=str(ROOT), **kwargs)

    def catalog(self):
        return json.loads((ROOT / 'data' / 'grade3_catalog.json').read_text())

    def send_json(self, data):
        body = json.dumps(data).encode('utf-8')
        self.send_response(HTTPStatus.OK)
        self.send_header('Content-Type', 'application/json; charset=utf-8')
        self.send_header('Content-Length', str(len(body)))
        self.send_header('Cache-Control', 'no-store')
        self.end_headers()
        self.wfile.write(body)

    def send_pdf(self, material_id):
        if not re.fullmatch(r'[0-9a-f]{20}', material_id):
            self.send_error(HTTPStatus.NOT_FOUND)
            return
        pair = lookup_material(material_index(self.catalog()), material_id)
        if pair is None:
            self.send_error(HTTPStatus.NOT_FOUND)
            return
        archive_name, internal_path = pair
        archive_path = (self.downloads_dir / archive_name).resolve()
        if archive_path.parent != self.downloads_dir:
            self.send_error(HTTPStatus.NOT_FOUND)
            return
        try:
            with zipfile.ZipFile(archive_path) as archive:
                content = archive.read(internal_path)
        except (FileNotFoundError, KeyError, zipfile.BadZipFile):
            self.send_error(HTTPStatus.NOT_FOUND)
            return
        filename = Path(internal_path).name
        self.send_response(HTTPStatus.OK)
        self.send_header('Content-Type', mimetypes.guess_type(filename)[0] or 'application/pdf')
        self.send_header('Content-Length', str(len(content)))
        self.send_header('Content-Disposition', 'inline; filename="%s"' % filename.replace('"', ''))
        self.send_header('Cache-Control', 'private, no-store')
        self.end_headers()
        self.wfile.write(content)

    def do_GET(self):
        path = urlparse(self.path).path
        if path == '/api/catalog':
            self.send_json(self.catalog())
            return
        if path.startswith('/api/pdf/'):
            self.send_pdf(unquote(path[len('/api/pdf/'):]))
            return
        super().do_GET()


def run(port, downloads_dir):
    def handler(*args, **kwargs):
        return ShowcaseHandler(*args, downloads_dir=downloads_dir, **kwargs)
    server = ThreadingHTTPServer(('127.0.0.1', port), handler)
    print('Serving Grade 3 showcase at http://127.0.0.1:%s' % port)
    server.serve_forever()


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('--port', type=int, default=8899)
    parser.add_argument('--downloads-dir', type=Path, default=DEFAULT_DOWNLOADS)
    args = parser.parse_args()
    run(args.port, args.downloads_dir)