"""Mail utility helpers."""

import re
from datetime import datetime
from email.header import decode_header
from email.utils import mktime_tz, parsedate_tz
from typing import Any


def decode_header_value(value: Any) -> str:
    """Decode email header value safely."""
    if value is None:
        return ""
    raw = value if isinstance(value, str) else str(value)
    parts = decode_header(raw)
    result: list[str] = []
    for part, charset in parts:
        if isinstance(part, bytes):
            result.append(part.decode(charset or "utf-8", errors="replace"))
        else:
            result.append(part)
    return "".join(result)


def format_date(date_str: str | None) -> str:
    """Format email date string to local-friendly form."""
    if not date_str:
        return ""
    try:
        tt = parsedate_tz(date_str)
        if tt is None:
            return date_str
        ts = mktime_tz(tt)
        dt = datetime.fromtimestamp(ts)
        return dt.strftime("%Y-%m-%d %H:%M")
    except Exception:
        return date_str


def strip_html_tags(html: str) -> str:
    """Very basic HTML tag stripping for fallback text extraction."""
    text = re.sub(r"<script[^>]*>.*?</script>", "", html, flags=re.S)
    text = re.sub(r"<style[^>]*>.*?</style>", "", text, flags=re.S)
    # Replace block-level tags with newlines before stripping remaining tags
    text = re.sub(r"</(p|div|h[1-6]|li|tr|blockquote)>", "\n", text, flags=re.I)
    text = re.sub(r"<br\s*/?>", "\n", text, flags=re.I)
    text = re.sub(r"<[^>]+>", "", text)
    text = re.sub(r"&nbsp;", " ", text)
    text = re.sub(r"&lt;", "<", text)
    text = re.sub(r"&gt;", ">", text)
    text = re.sub(r"&amp;", "&", text)
    text = re.sub(r"\n\s*\n+", "\n\n", text)
    return text.strip()


def truncate_text(text: str, max_len: int = 60) -> str:
    """Truncate text with ellipsis."""
    if len(text) <= max_len:
        return text
    return text[: max_len - 1] + "…"