"""
Frontmatter Generator Tool for Smolagents

This tool helps generate consistent YAML frontmatter for documents,
useful for RAG systems, static site generators, and document organization.
Integrates with TextInspectorTool and MarkdownConverter for a complete
document processing pipeline.
"""

import re
import yaml
import json
from datetime import datetime
from typing import Dict, List, Optional, Any, Union
from smolagents import Tool


class FrontmatterGeneratorTool(Tool):
    """Tool for generating and manipulating YAML frontmatter in documents."""

    name = "frontmatter_generator"
    description = """
    Generates or extracts YAML frontmatter for documents. Frontmatter provides structured 
    metadata for documents including title, author, date, description, and tags.
    Useful for document organization, RAG systems, and static site generators.
    Works with content from the inspect_file_as_text tool to add metadata to documents.
    """

    inputs = {
        "content": {
            "type": "string",
            "description": "Document content (with or without existing frontmatter)",
        },
        "title": {"type": "string", "description": "Document title", "nullable": True},
        "author": {
            "type": "string",
            "description": "Document author(s)",
            "nullable": True,
        },
        "date": {
            "type": "string",
            "description": "Document date in YYYY-MM-DD format (defaults to today if not provided)",
            "nullable": True,
        },
        "date_format": {
            "type": "string",
            "description": "Format string for the document date (e.g., '%Y-%m-%d', '%d/%m/%Y'). Defaults to '%Y-%m-%d'",
            "nullable": True,
            "default": "%Y-%m-%d",
        },
        "description": {
            "type": "string",
            "description": "Brief description of the document",
            "nullable": True,
        },
        "tags": {
            "type": "string",
            "description": "Comma-separated list of tags",
            "nullable": True,
        },
        "additional_fields": {
            "type": "string",
            "description": "JSON string with additional frontmatter fields",
            "nullable": True,
        },
        "mode": {
            "type": "string",
            "description": "Operation mode: 'generate' (create new), 'extract' (get existing), 'update' (modify existing), or 'strip' (remove)",
            "default": "generate",
        },
    }
    output_type = "string"

    # Regular expression to detect and extract YAML frontmatter
    FRONTMATTER_PATTERN = r"^---\s*\n(.*?)\n---\s*\n"

    def forward(
        self,
        content: str,
        title: Optional[str] = None,
        author: Optional[str] = None,
        date: Optional[str] = None,
        date_format: Optional[str] = "%Y-%m-%d",
        description: Optional[str] = None,
        tags: Optional[str] = None,
        additional_fields: Optional[str] = None,
        mode: str = "generate",
    ) -> str:
        """
        Process document content based on specified mode.

        Args:
            content: Document content with or without frontmatter
            title: Document title
            author: Document author(s)
            date: Document date (YYYY-MM-DD)
            date_format: strftime format string
            description: Brief document description
            tags: Comma-separated list of tags
            additional_fields: JSON string with additional fields
            mode: Operation mode (generate, extract, update, strip)

        Returns:
            Processed document or extracted frontmatter
        """
        # Validate inputs
        if not isinstance(content, str):
            return "Error: Content must be a string"
        if title and not isinstance(title, str):
            return "Error: Title must be a string"
        if author and not isinstance(author, str):
            return "Error: Author must be a string"
        if date and not isinstance(date, str):
            return "Error: Date must be a string"
        if description and not isinstance(description, str):
            return "Error: Description must be a string"
        if tags and not isinstance(tags, str):
            return "Error: Tags must be a string"
        if additional_fields and not isinstance(additional_fields, str):
            return "Error: Additional_fields must be a string"
        if not isinstance(mode, str):
            return "Error: Mode must be a string"

        # Validate mode
        valid_modes = ["generate", "extract", "update", "strip"]
        if mode not in valid_modes:
            return f"Error: Invalid mode '{mode}'. Valid options are: {', '.join(valid_modes)}"

        # Handle empty content
        if not content or not content.strip():
            if mode == "generate":
                # We can still generate frontmatter from provided fields
                content = ""
            else:
                return "Error: Empty content provided"

        # Special handling for TextInspectorTool output
        if content.startswith("Document content:"):
            content = content[len("Document content:"):].strip()
        
        # Process based on mode
        try:
            if mode == "extract":
                return self._extract_frontmatter(content)
            elif mode == "strip":
                return self._strip_frontmatter(content)
            elif mode == "update":
                return self._update_frontmatter(
                    content,
                    title,
                    author,
                    date,
                    description,
                    tags,
                    additional_fields,
                    date_format,
                )
            else:  # generate
                return self._generate_frontmatter(
                    content,
                    title,
                    author,
                    date,
                    description,
                    tags,
                    additional_fields,
                    date_format,
                )
        except Exception as e:
            return f"Error processing frontmatter: {str(e)}"

    def _extract_frontmatter(self, content: str) -> str:
        """Extract and return existing frontmatter as formatted YAML."""
        match = re.search(self.FRONTMATTER_PATTERN, content, re.DOTALL)
        if not match:
            return "No frontmatter found in the document"

        try:
            yaml_content = match.group(1)
            # Parse and reformat for consistency
            frontmatter_dict = yaml.safe_load(yaml_content)
            return f"Extracted frontmatter:\n\n```yaml\n{yaml.dump(frontmatter_dict, sort_keys=False, default_flow_style=False)}```"
        except yaml.YAMLError:
            return "Found frontmatter but failed to parse it as valid YAML"

    def _strip_frontmatter(self, content: str) -> str:
        """Remove frontmatter from document and return clean content."""
        result = re.sub(self.FRONTMATTER_PATTERN, "", content, count=1, flags=re.DOTALL)

        # Check if anything was actually removed
        if result == content:
            return "No frontmatter found to strip. Content unchanged."

        return result.strip()

    def _parse_additional_fields(self, additional_fields: str) -> Dict[str, Any]:
        """Parse the additional_fields JSON string into a dictionary."""
        if not additional_fields:
            return {}

        try:
            return json.loads(additional_fields)
        except json.JSONDecodeError:
            raise ValueError("additional_fields must be a valid JSON string")

    def _infer_title_from_content(self, content: str) -> Optional[str]:
        """Attempt to infer document title from content."""
        # Try to find the first heading
        heading_match = re.search(r"^#\s+(.+)$", content, re.MULTILINE)
        if heading_match:
            return heading_match.group(1).strip()

        # Try to find the first non-empty line
        lines = content.split("\n")
        for line in lines:
            if line.strip():
                # Limit to a reasonable title length
                return line.strip()[:100]

        return None

    def _parse_tags(self, tags_string: str) -> List[str]:
        """Parse comma-separated tags into a list."""
        if not tags_string:
            return []

        # Split by comma and clean each tag
        tag_list = [tag.strip() for tag in tags_string.split(",")]
        # Remove any empty tags
        return [tag for tag in tag_list if tag]

    def _parse_flexible_date(
        self, date_str: str, date_format: Optional[str] = None
    ) -> str:
        """
        Try to parse dates in various formats and convert to YYYY-MM-DD.

        Args:
            date_str: The date string to parse
            date_format: Optional preferred format to try first

        Returns:
            Formatted date as string (YYYY-MM-DD by default)
        """
        if not date_str:
            return datetime.now().strftime("%Y-%m-%d")

        # If a specific format is provided, try it first
        if date_format:
            try:
                parsed_date = datetime.strptime(date_str, date_format)
                return parsed_date.strftime("%Y-%m-%d")
            except ValueError:
                # If it fails, continue with other formats
                pass

        # Common formats to try
        formats = [
            "%Y-%m-%d",  # 2013-03-13
            "%d %B %Y",  # 13 March 2013
            "%B %Y",  # September 2013
            "%Y",  # 1958
            "%d/%m/%Y",  # 13/03/2013
            "%m/%d/%Y",  # 03/13/2013
            "%d-%m-%Y",  # 13-03-2013
            "%m-%d-%Y",  # 03-13-2013
            "%Y/%m/%d",  # 2013/03/13
        ]

        for fmt in formats:
            try:
                parsed_date = datetime.strptime(date_str, fmt)
                return parsed_date.strftime("%Y-%m-%d")
            except ValueError:
                continue

        # If no format matched, return the original string
        return date_str

    def _update_frontmatter(
        self,
        content: str,
        title: Optional[str] = None,
        author: Optional[str] = None,
        date: Optional[str] = None,
        description: Optional[str] = None,
        tags: Optional[str] = None,
        additional_fields: Optional[str] = None,
        date_format: Optional[str] = None,
    ) -> str:
        """Update existing frontmatter with new values."""
        # Check if frontmatter exists
        match = re.search(self.FRONTMATTER_PATTERN, content, re.DOTALL)
        if not match:
            # If no frontmatter exists, generate new one
            return self._generate_frontmatter(
                content,
                title,
                author,
                date,
                description,
                tags,
                additional_fields,
                date_format,
            )

        # Parse existing frontmatter
        yaml_content = match.group(1)
        try:
            frontmatter_dict = yaml.safe_load(yaml_content) or {}
        except yaml.YAMLError:
            frontmatter_dict = {}

        # Update with new values if provided
        if title:
            frontmatter_dict["title"] = title
        if author:
            frontmatter_dict["author"] = author
        if date:
            # Try to parse the date with the flexible parser
            frontmatter_dict["date"] = self._parse_flexible_date(date, date_format)
        if description:
            frontmatter_dict["description"] = description
        if tags:
            frontmatter_dict["tags"] = self._parse_tags(tags)

        # Add additional fields
        if additional_fields:
            additional_dict = self._parse_additional_fields(additional_fields)
            frontmatter_dict.update(additional_dict)

        # Generate new frontmatter
        new_frontmatter = yaml.dump(
            frontmatter_dict, sort_keys=False, default_flow_style=False
        )
        new_frontmatter = f"---\n{new_frontmatter}---\n\n"

        # Replace old frontmatter with new one
        return re.sub(
            self.FRONTMATTER_PATTERN, new_frontmatter, content, count=1, flags=re.DOTALL
        )

    def _generate_frontmatter(
        self,
        content: str,
        title: Optional[str] = None,
        author: Optional[str] = None,
        date: Optional[str] = None,
        description: Optional[str] = None,
        tags: Optional[str] = None,
        additional_fields: Optional[str] = None,
        date_format: Optional[str] = None,
    ) -> str:
        """Generate new frontmatter and prepend to content."""
        # Strip any existing frontmatter
        clean_content = (
            self._strip_frontmatter(content) if isinstance(content, str) else ""
        )

        # Build frontmatter dictionary
        frontmatter_dict = {}

        # Try to infer title if not provided
        if title:
            frontmatter_dict["title"] = title
        else:
            inferred_title = self._infer_title_from_content(clean_content)
            if inferred_title:
                frontmatter_dict["title"] = inferred_title

        # Add other fields if provided
        if author:
            frontmatter_dict["author"] = author

        # Process date with flexible parser
        if date:
            frontmatter_dict["date"] = self._parse_flexible_date(date, date_format)
        else:
            # Use current date with provided format or default
            format_to_use = date_format or "%Y-%m-%d"
            frontmatter_dict["date"] = datetime.now().strftime(format_to_use)

        if description:
            frontmatter_dict["description"] = description

        if tags:
            frontmatter_dict["tags"] = self._parse_tags(tags)

        # Add additional fields
        if additional_fields:
            additional_dict = self._parse_additional_fields(additional_fields)
            frontmatter_dict.update(additional_dict)

        # Generate YAML frontmatter
        frontmatter_yaml = yaml.dump(
            frontmatter_dict, sort_keys=False, default_flow_style=False
        )
        frontmatter = f"---\n{frontmatter_yaml}---\n\n"

        # Combine frontmatter with content
        return frontmatter + clean_content