import sys
import os
from fastcgi import fastcgi
from urllib.parse import parse_qs
from pathlib import Path
import pickle
from dataclasses import dataclass

CACHE_PATH = Path(__file__).parent / "mentions.pickle"

print("FastCGI server starting... unix socket to be located at")
print(Path.cwd()/"fcgi.sock")

@dataclass
class Mention:
    source: str
    target: str

    @staticmethod
    def load_past_mentions() -> list["Mention"]:
        if CACHE_PATH.exists():
            with open(CACHE_PATH, "rb") as fo:
                return pickle.load(fo)
        return []

    @staticmethod
    def save_past_mentions(mentions: list["Mention"]):
        with open(CACHE_PATH, "wb") as fo:
            return pickle.dump(mentions, fo)

    @classmethod
    def add_mention(cls, mention: "Mention"):
        cache = cls.load_past_mentions()
        if mention not in cache:
            cache.append(mention)
        cls.save_past_mentions(cache)

@fastcgi()
def handler():
    try:
        url = os.environ["REQUEST_URL"]
        method = os.environ["REQUEST_METHOD"]
        if method == "POST":
            payload = sys.stdin.read()
            data = parse_qs(payload)
            source = data["source"][-1]
            target = data["target"][-1]
            Mention.add_mention(Mention(source, target))
            if source == target:
                raise Exception()
            print("Status: 202 Accepted\r")
            print("Content-Type: text/plain; charset=utf-8\r\n\r")
            print("Thanks for mentioning us!")
            print(source)
        elif method == "GET":
            print("Status: 200 OK\r")
            print("Content-Type: text/plain; charset=utf-8\r\n\r")
            for mention in Mention.load_past_mentions():
                print(f"<{mention.source}> mentioned <{mention.target}>")
        else:
            raise Exception()
    except Exception as e:
        print("Status: 400 Bad Request\r\n\r")