import argparse
import enum
import errno
import logging
import requests
import sys
import stat

from datetime import datetime as dtp
from fuse import (
    FUSE,
    Operations,
    FuseOSError,
    LoggingMixIn,
    fuse_exit,
    fuse_get_context,
)
import urllib.parse


class APIChoice(enum.Enum):
    ACTIVITYPUB = "ActivityPub"
    MASTODON = "Mastodon"


api_url_ap_template = "https://{server}/users/{user}/outbox?page=true"
api_url_m_lookup_template = "https://{server}/api/v1/accounts/lookup"
api_url_m_status_template = "https://{server}/api/v1/accounts/{uid}/statuses"


class Status(object):
    def __init__(self, id: str, content: str, published: str):
        self.id = id
        self.content = content
        self.published = published


class StatusProvider:
    def load_statuses(self) -> list[Status]:
        raise NotImplementedError

    def _fallback_not_found(self):
        return [Status("not-found", "User not found", "1970-01-01T00:00:00Z")]

    def _fallback_error(self, error_msg: str):
        return [Status("error", error_msg, "1970-01-01T00:00:00Z")]


class ActivityPubStatusProvider(StatusProvider):
    def __init__(self, server: str, user: str):
        self.server = server
        self.user = user

    def load_statuses(self) -> list[Status]:
        url = api_url_ap_template.format(server=self.server, user=self.user)
        res = requests.get(url)
        if res.status_code == 404:
            return self._fallback_not_found()

        try:
            res.raise_for_status()
        except requests.exceptions.RequestException as e:
            logging.error("Request error: %s", e)
            return self._fallback_error(getattr(e, "message", str(e)))

        stats = res.json()
        status_items = stats.get("orderedItems", None)
        if not status_items:
            return self._fallback_error("Malformed content in querying AP outbox.")

        return [
            Status(
                s["object"]["id"].split("/")[-1],
                s["object"]["content"],
                s["object"]["published"],
            )
            for s in status_items
            if s["type"] == "Create"
        ]


class MastodonStatusProvider(StatusProvider):
    def __init__(self, server: str, user: str):
        self.server = server
        self.user = user
        self.userid = 0

    def load_statuses(self) -> list[Status]:
        url = api_url_m_lookup_template.format(server=self.server)
        url += "?" + urllib.parse.urlencode({"acct": self.user})
        res = requests.get(url)
        if res.status_code == 404:
            return self._fallback_not_found()
        try:
            res.raise_for_status()
        except requests.exceptions.RequestException as e:
            logging.error("Request error: %s", e)
            return self._fallback_error(getattr(e, "message", str(e)))

        user = res.json()
        self.userid = user.get("id")
        if not self.userid:
            return self._fallback_error("Malformed content in querying user ID.")

        url = api_url_m_status_template.format(
            server=self.server, uid=urllib.parse.quote(self.userid)
        )
        res = requests.get(url)
        if res.status_code == 404:
            return self._fallback_not_found()
        try:
            res.raise_for_status()
        except requests.exceptions.RequestException as e:
            logging.error("Request error: %s", e)
            return self._fallback_error(getattr(e, "message", str(e)))
        statuses = res.json()
        return [
            Status(
                s["id"],
                s["content"],
                s["created_at"],
            )
            for s in statuses
        ]


class StatusFileSystem(Operations, LoggingMixIn):
    def __init__(self, api: APIChoice, server: str, user: str):
        self.statuses: list[Status] = []
        self.fd = 0
        self.api = api
        if api == APIChoice.MASTODON:
            self.status_provider = MastodonStatusProvider(server, user)
        else:
            self.status_provider = ActivityPubStatusProvider(server, user)

    def getattr(self, path, fh=None):
        (uid, gid, _) = fuse_get_context()
        if path == "/":
            return {
                "st_mode": (stat.S_IFDIR | 0o700),  # Directory
                "st_nlink": 2,
                "st_uid": uid,
                "st_gid": gid,
            }
        found = next((s for s in self.statuses if "/" + s.id == path), None)
        if found:
            published_dt = dtp.fromisoformat(found.published)
            pubunix = published_dt.timestamp()
            return {
                "st_mode": (stat.S_IFREG | 0o400),
                "st_size": len(found.content.encode("utf8")),
                "st_nlink": 1,
                "st_uid": uid,
                "st_gid": gid,
                "st_ctime": pubunix,
                "st_mtime": pubunix,
            }
        raise FuseOSError(errno.ENOENT)

    def list_dir(self) -> list[str]:
        return [s.id for s in self.statuses]

    def readdir(self, path, fh):
        dir_entries = []
        if path != "/":
            raise FuseOSError(errno.ENOENT)
        dir_entries = [".", ".."]
        if not self.statuses:
            self.statuses = self.status_provider.load_statuses()
        dir_entries += self.list_dir()
        return dir_entries

    def open(self, path, flags):
        self.fd += 1
        return self.fd

    def read(self, path, size, offset, fh):
        found = next(s for s in self.statuses if "/" + s.id == path)
        if found:
            return found.content.encode("utf8")
        raise FuseOSError(errno.ENOENT)


def parse_arguments():
    parser = argparse.ArgumentParser(
        description="Mount a read-only FUSE filesystem for ActivityPub or Mastodon"
    )
    parser.add_argument(
        "mountpoint", help="The directory where the filesystem will be mounted"
    )
    group = parser.add_mutually_exclusive_group(required=True)
    group.add_argument(
        "-a", "--activitypub", action="store_true", help="Use ActivityPub API"
    )
    group.add_argument("-m", "--mastodon", action="store_true", help="Use Mastodon API")
    parser.add_argument("-s", "--server", required=True, help="The server/host URL")
    parser.add_argument(
        "-u", "--username", required=True, help="The username to fetch statuses for"
    )

    args = parser.parse_args()

    if args.activitypub:
        args.api_choice = APIChoice.ACTIVITYPUB
    elif args.mastodon:
        args.api_choice = APIChoice.MASTODON
    else:
        parser.error("Must choose either ActivityPub or Mastodon API")

    return args


def main(args):
    try:
        FUSE(
            StatusFileSystem(args.api_choice, args.server, args.username),
            args.mountpoint,
            nothreads=True,
            foreground=True,
        )
    except:
        fuse_exit()
        raise


if __name__ == "__main__":
    logging.basicConfig(level=logging.DEBUG)
    args = parse_arguments()
    main(args)