#!/usr/bin/env python3
"""Offline server for the Trivy documentation mirror (Python 3.9+ stdlib only).

    python3 serve.py [--host 127.0.0.1] [--port 8080]

Then open http://127.0.0.1:8080/ in a browser.
"""
import argparse
import http.server
import os
import posixpath
import sys
import urllib.parse

ROOT = os.path.join(os.path.dirname(os.path.abspath(__file__)), "site")
HOME = "/docs/latest/guide/"
NOT_FOUND = os.path.join(ROOT, "docs", "latest", "404.html")

# Mirrored release; tools/mirror.sh updates this line.
VERSION = "v0.74"

# Same behaviour as www.trivy.dev: the bare docs roots redirect to the guide.
REDIRECTS = {"/", "/docs", "/docs/", "/docs/latest", "/docs/latest/"}
# The version selector links to /docs/<version>/; only the latest version is mirrored.
VERSION_ALIASES = (f"/docs/{VERSION}",)
# 404.html loads its CSS/JS from absolute /<version>/assets/... paths.
INTERNAL_PREFIX = f"/{VERSION}/"


class Handler(http.server.SimpleHTTPRequestHandler):
    extensions_map = {
        **http.server.SimpleHTTPRequestHandler.extensions_map,
        ".js": "text/javascript",
        ".json": "application/json",
        ".woff2": "font/woff2",
        ".woff": "font/woff",
        ".svg": "image/svg+xml",
        ".xml": "application/xml",
    }

    def __init__(self, *args, **kwargs):
        super().__init__(*args, directory=ROOT, **kwargs)

    def _redirect(self, location):
        self.send_response(302)
        self.send_header("Location", location)
        self.send_header("Content-Length", "0")
        self.end_headers()

    def _route(self):
        """Return True if the request was fully handled here."""
        parts = urllib.parse.urlsplit(self.path)
        path = urllib.parse.unquote(parts.path)
        query = f"?{parts.query}" if parts.query else ""

        if path in REDIRECTS:
            self._redirect(HOME)
            return True
        # On an unknown top-level URL the 404 page resolves these against "/".
        if path == "/versions.json":
            self.path = "/docs/versions.json"
        elif path.startswith("/search/"):
            self.path = "/docs/latest" + self.path
        elif path.startswith(INTERNAL_PREFIX):
            self.path = "/docs/latest/" + self.path[len(INTERNAL_PREFIX):]
        parts = urllib.parse.urlsplit(self.path)
        path = urllib.parse.unquote(parts.path)
        for alias in VERSION_ALIASES:
            if path == alias or path.startswith(alias + "/"):
                self._redirect("/docs/latest" + path[len(alias):] + query)
                return True

        fs_path = self.translate_path(parts.path)
        if os.path.isdir(fs_path):
            if not path.endswith("/"):
                self._redirect(parts.path + "/" + query)
                return True
            fs_path = os.path.join(fs_path, "index.html")
        if not os.path.isfile(fs_path):
            self._send_404()
            return True
        return False

    def _send_404(self):
        body = b"404 Not Found"
        ctype = "text/plain; charset=utf-8"
        if os.path.isfile(NOT_FOUND):
            with open(NOT_FOUND, "rb") as f:
                body = f.read()
            ctype = "text/html; charset=utf-8"
        self.send_response(404)
        self.send_header("Content-Type", ctype)
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        if self.command != "HEAD":
            self.wfile.write(body)

    def do_GET(self):
        if not self._route():
            super().do_GET()

    def do_HEAD(self):
        if not self._route():
            super().do_HEAD()

    def list_directory(self, path):  # never expose directory listings
        self._send_404()
        return None

    def log_message(self, fmt, *args):
        if not self.server.quiet:
            super().log_message(fmt, *args)


def main():
    ap = argparse.ArgumentParser(description="Serve the offline Trivy docs mirror.")
    ap.add_argument("--host", default="127.0.0.1", help="bind address (default 127.0.0.1; 0.0.0.0 for LAN)")
    ap.add_argument("--port", type=int, default=8080, help="port (default 8080)")
    ap.add_argument("--quiet", action="store_true", help="do not log each request")
    args = ap.parse_args()

    if not os.path.isfile(os.path.join(ROOT, "docs", "latest", "guide", "index.html")):
        sys.exit(f"error: mirror not found under {ROOT}")

    server = http.server.ThreadingHTTPServer((args.host, args.port), Handler)
    server.quiet = args.quiet
    shown = "127.0.0.1" if args.host in ("0.0.0.0", "") else args.host
    print(f"Serving Trivy docs from {ROOT}")
    print(f"Open http://{shown}:{args.port}/   (Ctrl+C to stop)")
    try:
        server.serve_forever()
    except KeyboardInterrupt:
        print("\nstopped")
    finally:
        server.server_close()


if __name__ == "__main__":
    main()