from __future__ import annotations

import re

_RE_STRIP_MARKDOWN_LINK = re.compile(r"\[([^\]]*)\]\([^)]+\)")
_RE_STRIP_MARKDOWN_IMAGE = re.compile(r"!\[([^\]]*)\]\([^)]+\)")


def markdown_to_plaintext(md_text: str) -> str:
    result = md_text
    result = re.sub(r"\*\*(.+?)\*\*", lambda m: m.group(1).upper(), result)
    result = re.sub(r"__([^_]+)__", lambda m: m.group(1).upper(), result)
    result = re.sub(r"\*([^*]+)\*", r"_\1_", result)
    result = re.sub(r"_([^_]+)_", r"_\1_", result)
    result = re.sub(r"~~(.+?)~~", "", result)
    result = _RE_STRIP_MARKDOWN_IMAGE.sub(r"[\1]", result)
    result = _RE_STRIP_MARKDOWN_LINK.sub(lambda m: f"{m.group(1)} ({m.group(0).split('](')[1].rstrip(')')})", result)
    result = re.sub(r"```(\w*)\n(.*?)```", r"[CODE]\n\2\n[/CODE]", result, flags=re.DOTALL)
    result = result.replace(" & ", " & ")
    result = result.replace(" < ", " < ")
    result = result.replace(" > ", " > ")
    return result.strip()


def convert_table_to_bullets(md_text: str) -> str:
    lines = md_text.split("\n")
    result: list[str] = []
    in_table = False
    headers: list[str] = []

    for line in lines:
        stripped = line.strip()
        if stripped.startswith("|") and stripped.endswith("|"):
            cells = [c.strip() for c in stripped[1:-1].split("|")]
            if not in_table:
                headers = cells
                in_table = True
                continue
            if all(re.match(r"^[-:]+$", c) for c in cells):
                continue
            for i, header in enumerate(headers):
                value = cells[i] if i < len(cells) else ""
                result.append(f"  {header}: {value}")
        else:
            if in_table:
                in_table = False
            result.append(line)

    return "\n".join(result)


def split_plaintext_chunks(text: str, limit: int = 4000) -> list[str]:
    if len(text) <= limit:
        return [text]

    chunks: list[str] = []
    lines = text.split("\n")
    current = ""
    for line in lines:
        if len(current) + len(line) + 1 > limit and current:
            chunks.append(current.rstrip())
            current = line
        else:
            current = current + "\n" + line if current else line
    if current:
        chunks.append(current.rstrip())
    return chunks


class IMessageFormatAdapter:

    def format_for_imessage(self, md_text: str) -> str:
        text = convert_table_to_bullets(md_text)
        return markdown_to_plaintext(text)

    def chunk_text(self, text: str, limit: int = 4000) -> list[str]:
        return split_plaintext_chunks(text, limit)