from datetime import datetime
from html import escape
from typing import Any


def filter_articles(
    articles: list[dict[str, Any]],
    category_filter: str | None = None,
) -> list[dict[str, Any]]:
    if not category_filter:
        return articles
    wanted = category_filter.strip().lower()
    return [
        a
        for a in articles
        if any(c.lower() == wanted for c in a.get("categories", []))
    ]


def create_plain_text(articles: list[dict[str, Any]], title: str) -> str:
    lines = [title, "=" * len(title), ""]
    if not articles:
        lines.append("Keine Artikel im gewählten Zeitraum gefunden.")
        return "\n".join(lines)

    for idx, item in enumerate(articles, start=1):
        stamp = _format_ts(item.get("timestamp"))
        cat = ", ".join(item.get("categories", [])) or "Keine Kategorie"
        comment = item.get("comment") or "-"
        lines.extend(
            [
                f"{idx}. {item.get('title', 'Ohne Titel')}",
                f"   Zeit: {stamp}",
                f"   Benutzer: {item.get('user', '-')}",
                f"   Kategorien: {cat}",
                f"   Kommentar: {comment}",
                "",
            ]
        )
    return "\n".join(lines).strip()


def create_html(articles: list[dict[str, Any]], title: str) -> str:
    if not articles:
        return f"<h2>{escape(title)}</h2><p>Keine Artikel im gewählten Zeitraum gefunden.</p>"

    blocks = [f"<h2>{escape(title)}</h2>", "<ul>"]
    for item in articles:
        article_title = escape(item.get("title", "Ohne Titel"))
        stamp = escape(_format_ts(item.get("timestamp")))
        user = escape(item.get("user", "-"))
        cat = escape(", ".join(item.get("categories", [])) or "Keine Kategorie")
        comment = escape(item.get("comment") or "-")
        blocks.append(
            (
                "<li>"
                f"<strong>{article_title}</strong><br>"
                f"Zeit: {stamp}<br>"
                f"Benutzer: {user}<br>"
                f"Kategorien: {cat}<br>"
                f"Kommentar: {comment}"
                "</li>"
            )
        )
    blocks.append("</ul>")
    return "\n".join(blocks)


def _format_ts(value: str | None) -> str:
    if not value:
        return "-"
    try:
        dt = datetime.strptime(value, "%Y-%m-%dT%H:%M:%SZ")
        return dt.strftime("%d.%m.%Y %H:%M UTC")
    except ValueError:
        return value