import html
import re

MAX_SSML_CHARS = 8000
VOICE_FRIENDLY_MAX = 1000


class MarkdownToSSML:

    def __init__(self, max_chars: int = VOICE_FRIENDLY_MAX):
        self._max_chars = max_chars

    def convert(self, markdown_text: str) -> str:
        if not markdown_text:
            return "<speak></speak>"

        text = self._strip_markdown(markdown_text)
        text = html.escape(text, quote=False)
        text = self._restore_placeholders(text)
        text = self._truncate_if_needed(text)
        return f"<speak>{text}</speak>"

    def _strip_markdown(self, md: str) -> str:
        self._placeholders = []
        p = self._ph

        md = re.sub(r'```[\s\S]*?```', p('此处有代码，请在手机 App 中查看。'), md)
        md = re.sub(r'`([^`]+)`', r'\1', md)
        md = re.sub(r'!\[.*?\]\(.*?\)', p('此处有图片。'), md)
        md = re.sub(r'\*\*(.+?)\*\*', lambda m: p(f'<emphasis level="strong">{m.group(1)}</emphasis>'), md)
        md = re.sub(r'\*([^*]+)\*', lambda m: p(f'<emphasis level="moderate">{m.group(1)}</emphasis>'), md)
        md = re.sub(r'__([^_]+)__', r'\1', md)
        md = re.sub(r'_([^_]+)_', r'\1', md)
        md = re.sub(r'~~(.+?)~~', r'\1', md)
        md = re.sub(r'\[(.+?)\]\(.+?\)', r'\1', md)
        md = re.sub(r'^#{1,6}\s+', '', md, flags=re.MULTILINE)
        md = re.sub(r'^[\-\*\+]\s+', '', md, flags=re.MULTILINE)
        md = re.sub(r'^\d+\.\s+', '', md, flags=re.MULTILINE)
        md = re.sub(r'^>\s+', '', md, flags=re.MULTILINE)
        md = md.replace('---', p('<break time="500ms"/>'))
        md = md.replace('***', p('<break time="500ms"/>'))
        md = re.sub(r'\|.*\|', p('表格内容请在手机 App 中查看。'), md)
        md = re.sub(r'https?://\S+', '', md)
        return md.strip()

    def _ph(self, s: str) -> str:
        placeholder = f"\x00SSML{len(self._placeholders)}\x00"
        self._placeholders.append(s)
        return placeholder

    def _restore_placeholders(self, text: str) -> str:
        for i, val in enumerate(self._placeholders):
            text = text.replace(f"\x00SSML{i}\x00", val)
        return text

    def _truncate_if_needed(self, text: str) -> str:
        if len(text) <= self._max_chars:
            return text

        truncated = text[:self._max_chars]
        delimiters = ['。', '.', '\n', '；', ';', '，']
        best_pos = -1
        for delim in delimiters:
            pos = truncated.rfind(delim)
            if pos > best_pos:
                best_pos = pos

        if best_pos > 0:
            truncated = truncated[:best_pos + 1]

        truncated += '<break time="500ms"/>以上为部分回答，完整内容请在手机 App 中查看。'
        return truncated


def ssml_safe(text: str) -> str:
    if not text:
        return "<speak></speak>"
    text = html.escape(text, quote=False)
    return f"<speak>{text}</speak>"