from __future__ import annotations

import atexit
import os
import re
from time import time
from urllib.parse import urlsplit

import requests
from apscheduler.schedulers.background import BackgroundScheduler
from apscheduler.triggers.interval import IntervalTrigger

from blueprints.risdeveau.modules.api.scheduler_guard import should_start_scheduler
from blueprints.risdeveau.modules.api.shared_cache import (
    atomic_write_json,
    cache_file,
    load_json_if_newer,
)


EURORING_SOURCE_URL = os.environ.get(
    "EURORING_SOURCE_URL",
    "https://euroring.neocities.org/scripts/onionring-variables.js",
)
EURORING_SITE_URL = os.environ.get("EURORING_SITE_URL", "https://lair.moe")
EURORING_TIMEOUT = float(os.environ.get("EURORING_TIMEOUT", "10"))


data = {
    "enabled": bool(EURORING_SOURCE_URL and EURORING_SITE_URL),
    "status": "disabled",
    "source_url": EURORING_SOURCE_URL,
    "site_url": EURORING_SITE_URL,
    "ring_name": "",
    "index_url": None,
    "prev_url": None,
    "next_url": None,
    "count": 0,
    "last_updated": 0,
}

_IS_WRITER = should_start_scheduler() if data["enabled"] else False
_CACHE_PATH = cache_file("webring")
_CACHE_MTIME = 0.0


def _site_key(url: str) -> tuple[str, int | None, str, str]:
    parts = urlsplit(url.strip())
    hostname = (parts.hostname or "").lower()
    port = parts.port
    path = re.sub(r"/+$", "", parts.path or "")
    query = parts.query or ""
    return hostname, port, path, query


def _parse_js_string_value(text: str, variable: str) -> str | None:
    match = re.search(
        rf"var\s+{re.escape(variable)}\s*=\s*(['\"])(.*?)\1\s*;",
        text,
        re.S,
    )
    if not match:
        return None
    return match.group(2).strip()


def _parse_sites(text: str) -> list[str]:
    match = re.search(r"var\s+sites\s*=\s*\[(.*?)\]\s*;", text, re.S)
    if not match:
        raise ValueError("sites array not found")

    sites_block = match.group(1)
    sites: list[str] = []

    for raw_line in sites_block.splitlines():
        line = raw_line.strip()
        if not line or line.startswith("//"):
            continue

        site_match = re.match(
            r"(?P<quote>['\"])(?P<url>.*?)(?P=quote)\s*,?\s*(?://.*)?$",
            line,
        )
        if site_match:
            sites.append(site_match.group("url").strip())

    if not sites:
        raise ValueError("sites array is empty")

    return sites


def _compute_ring_payload(text: str) -> dict:
    sites = _parse_sites(text)
    target_key = _site_key(EURORING_SITE_URL)

    current_index = None
    for i, site in enumerate(sites):
        if _site_key(site) == target_key:
            current_index = i
            break

    if current_index is None:
        raise ValueError(f"site not found in ring: {EURORING_SITE_URL}")

    ring_name = _parse_js_string_value(text, "ringName") or "Webring"
    index_url = _parse_js_string_value(text, "indexPage")

    return {
        "enabled": True,
        "status": "success",
        "source_url": EURORING_SOURCE_URL,
        "site_url": EURORING_SITE_URL,
        "ring_name": ring_name,
        "index_url": index_url,
        "prev_url": sites[(current_index - 1) % len(sites)],
        "next_url": sites[(current_index + 1) % len(sites)],
        "count": len(sites),
        "last_updated": time(),
    }


def refresh_cache() -> None:
    global _CACHE_MTIME
    if _IS_WRITER:
        return

    payload, mtime = load_json_if_newer(_CACHE_PATH, _CACHE_MTIME)
    if payload is None:
        return

    data.update(payload)
    _CACHE_MTIME = mtime



def _persist_cache() -> None:
    if not _IS_WRITER:
        return
    atomic_write_json(_CACHE_PATH, data)



def fetch_webring() -> None:
    if not data["enabled"]:
        return

    previous_state = dict(data)

    try:
        response = requests.get(EURORING_SOURCE_URL, timeout=EURORING_TIMEOUT)
        response.raise_for_status()
        payload = _compute_ring_payload(response.text)
        data.update(payload)
    except Exception as exc:
        data.update({
            "enabled": True,
            "status": f"error: {exc}",
            "source_url": EURORING_SOURCE_URL,
            "site_url": EURORING_SITE_URL,
            "ring_name": data.get("ring_name") or "Webring",
            "index_url": data.get("index_url"),
            "prev_url": data.get("prev_url"),
            "next_url": data.get("next_url"),
            "count": data.get("count", 0),
            "last_updated": data.get("last_updated", 0),
        })

    if data != previous_state:
        _persist_cache()


if data["enabled"]:
    scheduler = BackgroundScheduler()

    if _IS_WRITER:
        scheduler.add_job(
            func=fetch_webring,
            trigger=IntervalTrigger(days=1),
            id="root.webring.refresh",
            replace_existing=True,
        )
        _persist_cache()
        scheduler.start()
        fetch_webring()
        atexit.register(lambda: scheduler.shutdown())
    else:
        refresh_cache()