"""Pure formatting utilities for LoRa-friendly text.

These helpers have NO dependency on the Hermes gateway package so they can be
imported and unit-tested in isolation (CI runs them without hermes-agent).
"""

import re

MAX_LORA_MESSAGE_LENGTH = 180  # Characters per packet to prevent LoRa airtime congestion

_MARKDOWN_RULES = (
    (r"\*\*(.+?)\*\*", r"\1"),  # bold
    (r"__(.+?)__", r"\1"),
    (r"\*(.+?)\*", r"\1"),      # italic
    (r"(?<!\w)_(.+?)_(?!\w)", r"\1"),
    (r"`(.+?)`", r"\1"),        # inline code
    (r"```[\w]*\n?", ""),       # code fences
    (r"!\[([^\]]*)\]\(([^)]+)\)", r"\1"),
    (r"\[([^\]]+)\]\(([^)]+)\)", r"\1 (\2)"),
    (r"^#+\s*", ""),            # headings
    (r"^\s*[-*+]\s+", "- "),    # normalize lists
)


def strip_markdown(text: str) -> str:
    """Convert markdown formatting into plain readable text suitable for radio."""
    if not text:
        return ""
    result = text
    for pattern, replacement in _MARKDOWN_RULES:
        result = re.sub(pattern, replacement, result, flags=re.MULTILINE)
    # Collapse multiple blank lines
    result = re.sub(r"\n{3,}", "\n\n", result)
    return result.strip()


def chunk_text(text: str, limit: int = MAX_LORA_MESSAGE_LENGTH) -> list:
    """Split text into smaller chunks for LoRa transmission, breaking at whitespace/newlines."""
    if not text:
        return []
    if len(text) <= limit:
        return [text]

    chunks = []
    remaining = text
    while remaining:
        if len(remaining) <= limit:
            chunks.append(remaining.strip())
            break
        split_at = remaining.rfind(" ", 0, limit)
        if split_at <= 0 or split_at < (limit // 3):
            newline_at = remaining.rfind("\n", 0, limit)
            if newline_at > 0:
                split_at = newline_at
            else:
                split_at = limit
        chunk = remaining[:split_at].strip()
        if chunk:
            chunks.append(chunk)
        remaining = remaining[split_at:].lstrip()
    return chunks