#!/usr/bin/env python3

DIR  = "./scripts/"
HOST = "localhost"
PORT = 9090


import argparse

parser = argparse.ArgumentParser(
    description="pier - Python Interpreter Executing Remotely",
    formatter_class=argparse.ArgumentDefaultsHelpFormatter
)

parser.add_argument("-d", "--dir",  default=DIR,  help="directory containing python scripts")
parser.add_argument("-H", "--host", default=HOST, help="host name")
parser.add_argument("-P", "--port", default=PORT, help="port number", type=int)

clargs = parser.parse_args()


from contextlib import redirect_stdout, redirect_stderr
from functools import lru_cache
from glob import glob
from io import StringIO

import os
import sys
import shlex
import traceback
import http.server
import socketserver


URL_SPACE = "%20"

exec_globals = {}
exec_locals = {}


class ScriptServer(http.server.SimpleHTTPRequestHandler):

    def do_GET(self):
        args = self.path.lstrip("/").replace(URL_SPACE, " ")
        args = shlex.split(args)

        if not args:
            super().do_GET()
            return

        scr = args[0]

        if not scr.endswith(".py"):
            scr += ".py"

        scripts = sorted(glob("*.py"))
        if scr not in scripts:
            printable_scripts = "\n".join(scripts)
            self.send_result(f"{scr} does not exist. choose from:\n", printable_scripts)
            return

        res = run_script(scr, args)

        msg = f"{scr} output:\n"
        msg += "_" * 80
        msg += f"\n{res}"
        self.send_result(msg)


    def send_result(self, *msg):
        self.send_response(200)
        self.send_header("Content-type", "text/html")
        self.end_headers()
        msg = encode_html(*msg)
        self.wfile.write(msg)
        print(msg)



def run_script(fn, args):
    sio = StringIO()
    with redirect_stdout(sio), redirect_stderr(sio):
        code = open_script(fn)
        old_sys_argv, sys.argv = sys.argv, args
        try:
            exec(code, exec_globals, exec_locals)
        except BaseException as e: # need to catch SystemExit etc. as well
            print("_" * 80)
            tn = type(e).__name__
            msg = f"{tn}: {e}"
            print(msg, file=sys.stderr)
            traceback.print_exc()
        sys.argv = old_sys_argv
    return sio.getvalue()

@lru_cache()
def open_script(fn):
    print("reading", fn)
    print("_" * 80)
    with open(fn) as f:
        src = f.read()
    code = compile(src, fn, "exec")
    return code

def encode_html(*msg):
    msg = (str(i) for i in msg)
    msg = " ".join(msg)
    msg = msg.split("\n")
    msg = "<br>".join(msg)
    msg = msg.encode()
    return msg



if __name__ == "__main__":
    try:
        os.chdir(clargs.dir)
    except Exception as e:
        tn = type(e).__name__
        msg = f"{tn}: {e}"
        raise SystemExit(msg)

    sys.path.insert(0, os.getcwd()) # add the script folder to the path

    host = clargs.host
    port = clargs.port

    socketserver.TCPServer.allow_reuse_address = True
    with socketserver.ThreadingTCPServer((host, port), ScriptServer) as httpd:
        print(f"serving at {host}:{port}")
        try:
            httpd.serve_forever()
        except KeyboardInterrupt:
            print()