from __future__ import annotations

import xml.etree.ElementTree as ET
from datetime import date, datetime
from email.utils import parsedate_to_datetime
from typing import Any, Callable

from ai_daily_report.models import SourceConfig
from ai_daily_report.normalize import clean_text


FetchText = Callable[[str, int], str]


def _parse_pubdate(value: str) -> str | None:
    if not value:
        return None
    try:
        return parsedate_to_datetime(value).isoformat()
    except Exception:
        return None


def _parse_run_date(value: str | None) -> date | None:
    if not value:
        return None
    try:
        return date.fromisoformat(value[:10])
    except ValueError:
        return None


def _parse_iso_date(value: str | None) -> date | None:
    if not value:
        return None
    try:
        return datetime.fromisoformat(value).date()
    except ValueError:
        return None


def _within_max_item_age(published_at: str | None, *, run_date: str | None, max_item_age_days: int | None) -> bool:
    if max_item_age_days is None:
        return True
    published_date = _parse_iso_date(published_at)
    current_date = _parse_run_date(run_date)
    if published_date is None or current_date is None:
        return True
    return (current_date - published_date).days <= max_item_age_days


def parse_rss_items(
    config: SourceConfig,
    xml_text: str,
    *,
    limit: int = 20,
    run_date: str | None = None,
) -> list[dict[str, Any]]:
    root = ET.fromstring(xml_text)
    channel = root.find("channel")
    raw_items = channel.findall("item") if channel is not None else []
    items: list[dict[str, Any]] = []
    for raw in raw_items:
        title = clean_text(raw.findtext("title") or "")
        if not title:
            continue
        summary = clean_text(raw.findtext("description") or "")
        published_at = _parse_pubdate(raw.findtext("pubDate") or "")
        if not _within_max_item_age(
            published_at,
            run_date=run_date,
            max_item_age_days=config.max_item_age_days,
        ):
            continue
        items.append(
            {
                "source_group": config.name,
                "source_label": config.name,
                "title_raw": title,
                "summary_raw": summary,
                "url": (raw.findtext("link") or "").strip(),
                "published_at": published_at,
                "origin_type": "rss",
                "section_hint": "",
                "language_hint": "en" if title.encode("utf-8").isascii() else "zh",
            }
        )
        if len(items) >= limit:
            break
    return items


def fetch_rss(config: SourceConfig, run_date: str, fetch_text: FetchText) -> list[dict[str, Any]]:
    return parse_rss_items(config, fetch_text(config.url, config.timeout_seconds), run_date=run_date)