"""
Variable Wrapper Utility
Automatically wraps variables in HTML content with tooltip spans
"""

import re
import html
from typing import List, Tuple
from .symbol_loader import get_symbol_definitions


class VariableWrapper:
    """Wraps known variables in HTML content with tooltip markup"""

    def __init__(self):
        """Initialize variable wrapper with symbol definitions"""
        self.symbols = get_symbol_definitions()
        self._build_patterns()

    def _build_patterns(self) -> None:
        """Build regex patterns for all known symbols"""
        # Get all symbols and sort by length (longest first) to avoid partial matches
        symbols_list = sorted(
            self.symbols.get_all_symbols(),
            key=len,
            reverse=True
        )

        # Single letters that commonly appear in regular text
        # Only match these in specific mathematical contexts
        common_words = {'A', 'I', 'V', 'P', 'Q', 'R', 'L', 'C', 'E', 'B', 'G', 'X', 'Y', 'Z', 'f', 'd', 'h'}

        # Very common English words that need extra-strict matching
        very_common = {'A', 'I'}

        self.patterns: List[Tuple[str, str]] = []
        self.context_patterns: List[Tuple[str, str]] = []  # Patterns requiring context

        for symbol in symbols_list:
            # Escape special regex characters
            escaped = re.escape(symbol)

            # For single-letter variables, only match in formula/code contexts
            if symbol in common_words:
                if symbol in very_common:
                    # Extra restrictive for A, I - only in clear math context
                    # Must be preceded by =, ×, +, -, /, ( with optional single space
                    # Multiple patterns to handle both "=A" and "= A" cases
                    # Use alternation to avoid variable-width lookbehind
                    pattern = f'(?<=[=×+\\-/\\(])\\s?({escaped})(?=[\\s=+\\-*/()\\[\\]])'
                    self.context_patterns.append((pattern, symbol))
                else:
                    # More restrictive pattern - requires mathematical context
                    # Match if preceded by: =, mathematical operators, but NOT punctuation
                    pattern = f'(?<=[=])\\s?({escaped})(?=[\\s=+\\-*/()\\[\\],;<>])|(?<=\\s)({escaped})(?=[\\s=+\\-*/()\\[\\],;<>])'
                    self.context_patterns.append((pattern, symbol))
            else:
                # Normal pattern for multi-character symbols
                # Use word boundaries but allow underscores and subscripts
                pattern = f'(?<!\\w)({escaped})(?!\\w)'
                self.patterns.append((pattern, symbol))

        print(f"[VariableWrapper] Built {len(self.patterns)} normal patterns + {len(self.context_patterns)} context-sensitive patterns")

    def wrap_variables(self, html_content: str) -> str:
        """
        Wrap known variables in HTML content with tooltip spans

        Args:
            html_content: HTML content to process

        Returns:
            HTML content with variables wrapped in tooltip spans
        """
        # Track which variables were found (for debugging)
        wrapped_vars = set()

        # Process normal patterns
        all_patterns = self.patterns + self.context_patterns

        for pattern, symbol in all_patterns:
            tooltip_text = self.symbols.get_tooltip(symbol)
            if not tooltip_text:
                continue

            # Escape for HTML attribute (newlines become &#10;)
            tooltip_escaped = html.escape(tooltip_text, quote=True).replace('\n', '&#10;')

            # Create replacement span with tooltip
            replacement = (
                f'<span class="var-tooltip" '
                f'data-symbol="{symbol}" '
                f'title="{tooltip_escaped}">'
                f'\\1'  # Captured group (the symbol itself)
                f'</span>'
            )

            # Count matches before replacement
            matches = list(re.finditer(pattern, html_content))

            if matches:
                wrapped_vars.add(symbol)

                # Replace pattern with wrapped version
                # Use negative lookahead to avoid wrapping already-wrapped variables
                pattern_with_check = f'(?<!var-tooltip">)(?<!var-tooltip" )(?<!title=")({pattern})(?!</span>)'
                html_content = re.sub(
                    pattern_with_check,
                    replacement,
                    html_content
                )

        if wrapped_vars:
            print(f"[VariableWrapper] Wrapped {len(wrapped_vars)} unique variables: {', '.join(sorted(wrapped_vars)[:10])}...")

        return html_content

    def wrap_in_context(self, html_content: str) -> str:
        """
        More sophisticated wrapping that parses HTML structure
        to avoid wrapping in code blocks, headings, etc.

        Args:
            html_content: HTML content to process

        Returns:
            HTML content with variables wrapped (context-aware)
        """
        # For now, use simple wrapping
        # TODO: Implement HTML parsing to be more selective
        # (e.g., skip <code>, <pre>, <h1>-<h6> tags)

        # Simple exclusion: Don't process content inside <code> or <pre>
        code_blocks = []

        def preserve_code(match):
            """Preserve code blocks and replace with placeholder"""
            code_blocks.append(match.group(0))
            return f"___CODE_BLOCK_{len(code_blocks) - 1}___"

        # Temporarily remove code blocks
        html_content = re.sub(
            r'<(code|pre)>(.*?)</\1>',
            preserve_code,
            html_content,
            flags=re.DOTALL
        )

        # Wrap variables
        html_content = self.wrap_variables(html_content)

        # Restore code blocks
        for i, code_block in enumerate(code_blocks):
            html_content = html_content.replace(
                f"___CODE_BLOCK_{i}___",
                code_block
            )

        return html_content