# markdown_sqlite.py
"""
This script processes a markdown file by reading its content and
updates an SQLite database with document content and metadata.
The user can then select specific topics based on command-line arguments.
The script tracks changes using MD5 hashes and ensures the database 
reflects the current state of the markdown file.
"""

import sqlite3
import hashlib
import argparse
import os
from datetime import datetime
from typing import List, Tuple, Optional
from markdown_it import MarkdownIt
from thefuzz import fuzz, process

class DatabaseManager:
    """Manages database connections and table creation."""

    def __init__(self, db_file: str):
        """Initialize the DatabaseManager."""
        self.conn: sqlite3.Connection = sqlite3.connect(db_file, timeout=10)
        self.cursor: sqlite3.Cursor = self.conn.cursor()
        self.create_tables()

    def create_tables(self) -> None:
        """Create necessary tables in the database if they don't exist."""
        self.cursor.executescript('''
            CREATE TABLE IF NOT EXISTS documents (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                name TEXT NOT NULL UNIQUE,
                file_path TEXT NOT NULL,
                md5sum TEXT,
                added_timestamp DATETIME DEFAULT CURRENT_TIMESTAMP,
                updated_timestamp DATETIME,
                deleted_timestamp DATETIME,
                isDeleted BOOLEAN DEFAULT 0
            );

            CREATE TABLE IF NOT EXISTS headings (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                level INTEGER NOT NULL,
                title TEXT NOT NULL,
                parent_id INTEGER,
                document_id INTEGER NOT NULL,
                added_timestamp DATETIME DEFAULT CURRENT_TIMESTAMP,
                updated_timestamp DATETIME,
                deleted_timestamp DATETIME,
                isDeleted BOOLEAN DEFAULT 0,
                FOREIGN KEY (parent_id) REFERENCES headings(id),
                FOREIGN KEY (document_id) REFERENCES documents(id)
            );

            CREATE TABLE IF NOT EXISTS body (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                content TEXT,
                heading_id INTEGER NOT NULL,
                document_id INTEGER NOT NULL,
                md5sum TEXT,
                added_timestamp DATETIME DEFAULT CURRENT_TIMESTAMP,
                updated_timestamp DATETIME,
                deleted_timestamp DATETIME,
                isDeleted BOOLEAN DEFAULT 0,
                FOREIGN KEY (heading_id) REFERENCES headings(id),
                FOREIGN KEY (document_id) REFERENCES documents(id)
            );
        ''')

    def close(self) -> None:
        """Close the database connection."""
        self.conn.close()

class DocumentManager:
    """Manages document-related operations in the database."""

    def __init__(self, db_manager: 'DatabaseManager'):
        self.db_manager: DatabaseManager = db_manager

    def document_exists(self, document_name: str) -> Optional[Tuple[int]]:
        """
        Check if a document exists in the database.

        Args:
            document_name: Name of the document to check.

        Returns:
            Document ID if it exists, None otherwise.
        """
        self.db_manager.cursor.execute('SELECT id FROM documents WHERE name = ?', (document_name,))
        return self.db_manager.cursor.fetchone()

    def create_document(self, name: str, file_path: str) -> Optional[int]:
        """Create a new document entry in the database."""
        now: str = datetime.now().isoformat()
        self.db_manager.cursor.execute('''
            INSERT INTO documents (name, file_path, added_timestamp) VALUES (?, ?, ?)
        ''', (name, file_path, now))
        self.db_manager.conn.commit()
        return self.db_manager.cursor.lastrowid

    def update_document(self, document_id: int, name: Optional[str] = None, file_path: Optional[str] = None) -> None:
        """Update an existing document in the database."""
        now: str = datetime.now().isoformat()
        if name:
            self.db_manager.cursor.execute('''
                UPDATE documents SET name = ?, updated_timestamp = ? WHERE id = ?
            ''', (name, now, document_id))
        if file_path:
            self.db_manager.cursor.execute('''
                UPDATE documents SET file_path = ?, updated_timestamp = ? WHERE id = ?
            ''', (file_path, now, document_id))
        self.db_manager.conn.commit()

    def soft_delete_document(self, document_id: int) -> None:
        """Soft delete a document by marking it as deleted in the database."""
        now: str = datetime.now().isoformat()
        self.db_manager.cursor.execute('''
            UPDATE documents SET isDeleted = 1, deleted_timestamp = ? WHERE id = ?
        ''', (now, document_id))
        self.db_manager.conn.commit()

    def read_documents(self) -> List[Tuple]:
        """Retrieve all non-deleted documents from the database."""
        self.db_manager.cursor.execute('SELECT * FROM documents WHERE isDeleted = 0')
        return self.db_manager.cursor.fetchall()

    def update_document_hash(self, document_id: int, md5sum: str) -> None:
        """Update the MD5 hash of a document in the database."""
        self.db_manager.cursor.execute('UPDATE documents SET md5sum = ? WHERE id = ?', (md5sum, document_id))
        self.db_manager.conn.commit()

class MarkdownProcessor:
    """Processes markdown files and stores content in the database."""

    def __init__(self, db_manager: 'DatabaseManager') -> None:
        """Initialize the MarkdownProcessor."""
        self.db_manager = db_manager

    def process_markdown(self, markdown_file: str, document_id: int) -> None:
        """Process a markdown file and store its content in the database."""
        markdown_text = self.read_markdown_file(markdown_file)
        md = MarkdownIt()
        tokens = md.parse(markdown_text)

        self.clear_document_content(document_id)
        self.store_markdown_content(tokens, document_id)

    def read_markdown_file(self, file_path: str) -> str:
        """Read content from a markdown file."""
        with open(file_path, 'r', encoding='utf-8') as file:
            return file.read()

    def clear_document_content(self, document_id: int) -> None:
        """Clear existing content for a document in the database."""
        self.db_manager.cursor.execute('DELETE FROM headings WHERE document_id = ?', (document_id,))
        self.db_manager.cursor.execute('DELETE FROM body WHERE document_id = ?', (document_id,))

    def store_markdown_content(self, tokens: List, document_id: int) -> None:
        """Store parsed markdown content in the database."""
        parent_stack: List[Tuple[int, int]] = []  # (level, heading_id)
        current_heading_id = None
        for token in tokens:
            if token.type == 'heading_open':
                level = int(token.tag.strip('h'))
                content_token = tokens[tokens.index(token) + 1]
                title = content_token.content
                
                # Find the appropriate parent
                while parent_stack and parent_stack[-1][0] >= level:
                    parent_stack.pop()
                
                parent_id = parent_stack[-1][1] if parent_stack else None
                current_heading_id = self.insert_heading(level, title, parent_id, document_id)
                
                parent_stack.append((level, current_heading_id))
            elif token.type == 'inline' and current_heading_id and token.content.strip():
                # Only insert non-empty content that's not part of a heading
                if tokens[tokens.index(token) - 1].type != 'heading_open':
                    self.insert_body(token.content, current_heading_id, document_id)
        
        self.db_manager.conn.commit()

    def insert_heading(self, level: int, title: str, parent_id: Optional[int], document_id: int) -> int:
        """Insert a heading into the database."""
        self.db_manager.cursor.execute('''
            INSERT INTO headings (level, title, parent_id, document_id)
            VALUES (?, ?, ?, ?)
        ''', (level, title, parent_id, document_id))
        return self.db_manager.cursor.lastrowid

    def insert_body(self, content: str, heading_id: int, document_id: int) -> None:
        """Insert body content into the database with checksumming."""
        md5sum = hashlib.md5(content.encode()).hexdigest()
        self.db_manager.cursor.execute('''
            INSERT INTO body (content, heading_id, document_id, md5sum)
            VALUES (?, ?, ?, ?)
        ''', (content, heading_id, document_id, md5sum))

class TopicReader:
    """Reads and retrieves topics from the database."""

    def __init__(self, db_manager: 'DatabaseManager'):
        """
        Initialize the TopicReader.

        Args:
            db_manager (DatabaseManager): An instance of DatabaseManager.
        """
        self.db_manager = db_manager

    def fetch_headings(self) -> List[Tuple[int, str, int]]:
        """
        Fetch all non-deleted headings from the database.
        """
        self.db_manager.cursor.execute('SELECT id, title, level FROM headings WHERE isDeleted = 0 ORDER BY level, id')
        return self.db_manager.cursor.fetchall()

    def fetch_topic_chain(self, heading_id: int) -> List[Tuple[int, str, int]]:
        """
        Fetch the topic chain (hierarchy of parent topics) for a given heading.

        Returns:
            List[Tuple[int, str, int]]: List of (id, title, level) tuples representing the topic chain.
        """
        chain = []
        current_id = heading_id

        while current_id is not None:
            self.db_manager.cursor.execute('SELECT id, title, level, parent_id FROM headings WHERE id = ?', (current_id,))
            result = self.db_manager.cursor.fetchone()
            if result:
                chain.append((result[0], result[1], result[2]))
                current_id = result[3]
            else:
                break

        return list(reversed(chain))
        
    def list_headings(self) -> str:
        """
        List all available headings in a hierarchical structure.

        Returns:
            str: A formatted string containing all headings.
        """
        headings = self.fetch_headings()
        result = "Available headings:\n"
        
        for _, title, level in headings:
            indent = "  " * (level - 1)
            result += f"{indent}- {title}\n"
        
        return result.strip()

    def fetch_body_and_subtopics(self, heading_id: int, include_subtopics: bool = True, level_offset: int = 0) -> str:
        """
        Fetch body content and subtopics for a given heading with improved Markdown formatting.
        
        Args:
            heading_id (int): ID of the heading to fetch.
            include_subtopics (bool): Whether to include subtopics in the result.
            level_offset (int): Offset to adjust heading levels for proper nesting.
            
        Returns:
            str: Formatted string containing the heading content and subtopics.
        """
        # Fetch the current heading and body content
        self.db_manager.cursor.execute('SELECT level, title FROM headings WHERE id = ?', (heading_id,))
        level, title = self.db_manager.cursor.fetchone()
        
        # Adjust the level based on the offset
        adjusted_level = max(1, level - level_offset)
    
        # Fetch the content for this heading
        self.db_manager.cursor.execute('SELECT content FROM body WHERE heading_id = ?', (heading_id,))
        rows = self.db_manager.cursor.fetchall()
        body_content = '\n'.join([row[0] for row in rows])
    
        # Construct the result with proper spacing
        result = f"\n{'#' * adjusted_level} {title}\n\n"
        if body_content.strip():
            result += f"{body_content.strip()}\n\n"
    
        if include_subtopics:
            # Fetch all subtopics that are children of the current heading
            subtopics = self._fetch_subtopics(heading_id, adjusted_level)
            for subtopic_id, _, _ in subtopics:
                # Recursively fetch subtopic content
                subtopic_content = self.fetch_body_and_subtopics(subtopic_id, include_subtopics=True, level_offset=level_offset)
                result += subtopic_content
    
        return result.strip() + "\n"  # Ensure there's a newline at the end of each section

    def get_topic_content(self, input_title: str) -> Optional[str]:
        """
        Get the content of a topic based on the input title, including its topic chain and subtopics.
    
        Returns:
            str or None: Formatted string containing the topic chain, content, and subtopics, or None if not found.
        """
        heading_id = self.find_closest_heading(input_title)
        if heading_id:
            topic_chain = self.fetch_topic_chain(heading_id)
            result = ""
            for i, (id, title, level) in enumerate(topic_chain):
                if id == heading_id:
                    # Fetch the full content for the selected topic and its subtopics
                    result += self.fetch_body_and_subtopics(id, include_subtopics=True, level_offset=i)
                else:
                    # Include only the heading chain without duplicating content
                    result += f"\n{'#' * (level - i)} {title}\n\n"
            return result.strip() + "\n"  # Ensure there's a final newline
        print(f"No topic found matching '{input_title}'.")
        return None

    def _fetch_subtopics(self, heading_id: int, parent_level: int) -> List[Tuple[int, int, str]]:
        """
        Fetch all subtopics that are children of the given heading.
        
        Args:
            heading_id (int): The parent heading ID.
            parent_level (int): The level of the parent heading.
            
        Returns:
            List of tuples containing the subtopic's ID, level, and title.
        """
        self.db_manager.cursor.execute('''
            SELECT id, level, title 
            FROM headings 
            WHERE parent_id = ? AND isDeleted = 0
            ORDER BY level, id
        ''', (heading_id,))
        return self.db_manager.cursor.fetchall()

    def find_closest_heading(self, input_title: str) -> Optional[int]:
        """
        Find the closest matching heading to the input title using fuzzy matching.

        Returns:
            int or None: ID of the closest matching heading, or None if no match found.
        """
        headings = self.fetch_headings()
        if not headings:
            print("No topics found in the database.")
            return None

        heading_titles = [title for _, title, _ in headings]
        closest_match, confidence = process.extractOne(input_title, heading_titles, scorer=fuzz.token_sort_ratio)

        if confidence < 50:
            print(f"No close matches found for '{input_title}' (Confidence: {confidence})")
            return None

        for heading_id, title, level in headings:
            if title == closest_match:
                return heading_id

        return None

def compute_file_hash(file_path: str) -> str:
    """
    Compute the MD5 hash of a file.
    """
    hash_md5 = hashlib.md5()
    with open(file_path, "rb") as f:
        for chunk in iter(lambda: f.read(4096), b""):
            hash_md5.update(chunk)
    return hash_md5.hexdigest()

def generate_calendar(year: int) -> str:
    """Generate a markdown calendar for the specified year."""
    calendar_markdown = f"# {year}\n\n"
    current_date = datetime.now().date()

    for month in range(1, 13):
        month_name = datetime(year, month, 1).strftime('%B')
        calendar_markdown += f"## {month:02d} / {month_name}\n\n"

        # Calculate the number of days in the month
        num_days = (datetime(year, month + 1, 1) - datetime(year, month, 1)).days if month < 12 else (datetime(year + 1, 1, 1) - datetime(year, month, 1)).days
        
        # Generate calendar entries for each day
        for day in range(1, num_days + 1):
            day_date = datetime(year, month, day).date()
            day_name = day_date.strftime('%a')
            
            # Check if this is the current day and make it bold if so
            if str(day_date) == str(current_date):
                calendar_markdown += f"**{day:02d} / {day_name}**\n"
            else:
                calendar_markdown += f"{day:02d} / {day_name}\n"

        calendar_markdown += "\n"  # Add a newline after each month

    return calendar_markdown
    
def convert_to_html(markdown_content: str) -> str:
    """
    Convert Markdown content to HTML.
    """
    md = MarkdownIt()
    html_content = md.render(markdown_content)
    
    # Wrap the content in a basic HTML structure
    html_document = f"""
    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>Calendar</title>
        <style>
            body {{ font-family: Arial, sans-serif; line-height: 1.6; padding: 20px; }}
            h1, h2, h3, h4, h5, h6 {{ margin-top: 24px; margin-bottom: 16px; }}
            h1 {{ font-size: 2em; }}
            h2 {{ font-size: 1.5em; }}
            h3 {{ font-size: 1.25em; }}
        </style>
    </head>
    <body>
    {html_content}
    </body>
    </html>
    """
    
    return html_document
    

def bootstrap_calendar(year: int, db_manager: DatabaseManager, markdown_file: str):
    """Generate and store a full year's markdown calendar in the database."""
    calendar_content = generate_calendar(year)
    
    # Write the calendar to the specified markdown file
    with open(markdown_file, 'w', encoding='utf-8') as f:
        f.write(calendar_content)

    # Now use the DocumentManager and MarkdownProcessor to read this file into the database
    document_manager = DocumentManager(db_manager)
    document_id = document_manager.create_document(os.path.basename(markdown_file), markdown_file)
    markdown_processor = MarkdownProcessor(db_manager)
    markdown_processor.process_markdown(markdown_file, document_id)
    print(f"Calendar for year {year} has been generated and stored in the database.")

def main():
    """
    This script processes a markdown file, updates an SQLite database,
    and optionally selects a topic based on user input.

    Initializes managers for database and markdown handling. Updates documents based on 
    MD5 hash changes, and if a topic is provided, retrieves and writes its content 
    to the markdown file.

    Args:
        -m, --markdown: Path to markdown file (default: 'calendar.md').
        -d, --database: Path to SQLite database file (default: 'markdown.db').
        topic_title: Optional topic for content selection (fuzzy matching enabled).
        --bootstrap: If provided, generates markdown calendar for the current year and loads it to the database.
        --ls: If provided, lists all available headings.
    """
    # Set up command-line argument parsing
    parser = argparse.ArgumentParser(description='Process markdown file and optionally select a topic.')
    parser.add_argument('-m', '--markdown', type=str, default='calendar.md', help='Input/output markdown file (default: calendar.md)')
    parser.add_argument('-d', '--database', type=str, default='markdown.db', help='SQLite database file (default: markdown.db)')
    parser.add_argument('topic_title', nargs='?', type=str, help='Topic title to select (fuzzy matching enabled)')
    parser.add_argument('--bootstrap', action='store_true', help='Generate markdown calendar for the current year and load it to the database.')
    parser.add_argument('--ls', action='store_true', help='List all available headings.')
    parser.add_argument('--html', action='store_true', help='Generate an HTML version of the output')
    args = parser.parse_args()

    # Use the provided or default file paths
    markdown_file = args.markdown
    database_file = args.database

    # Initialize manager objects for database operations
    db_manager = DatabaseManager(database_file)

    if args.bootstrap:
        bootstrap_calendar(datetime.now().year, db_manager, markdown_file)
        db_manager.close()
        return

    if args.ls:
        topic_reader = TopicReader(db_manager)
        print(topic_reader.list_headings())
        db_manager.close()
        return

    # Check if the markdown file exists
    if not os.path.exists(markdown_file):
        print(f"Error: Markdown file '{markdown_file}' not found. Use --bootstrap to create a new calendar.")
        db_manager.close()
        return

    document_manager = DocumentManager(db_manager)
    markdown_processor = MarkdownProcessor(db_manager)

    # Get the base name of the markdown file (without path)
    document_name = os.path.basename(markdown_file)

    # Check if the document already exists in the database
    document = db_manager.cursor.execute('SELECT id, file_path, md5sum, updated_timestamp FROM documents WHERE name = ?', (document_name,)).fetchone()

    # Compute the current MD5 hash of the markdown file
    current_file_hash = compute_file_hash(markdown_file)

    if document:
        # If the document exists in the database
        document_id, stored_file_path, stored_md5sum, last_updated = document

        if stored_file_path != markdown_file:
            print(f"Updating file path for '{document_name}' in the database...")
            document_manager.update_document(document_id, file_path=markdown_file)

        if stored_md5sum != current_file_hash:
            # If the file has changed since last update
            print(f"File '{document_name}' has changed. Updating the database...")
            document_manager.update_document_hash(document_id, current_file_hash)
            markdown_processor.process_markdown(markdown_file, document_id)
        else:
            # If the file hasn't changed
            print(f"File '{document_name}' has not changed. Skipping update.")
    else:
        # If the document doesn't exist in the database
        print(f"Document '{document_name}' not found in the database. Adding new entry...")
        document_id = document_manager.create_document(document_name, markdown_file)
        document_manager.update_document_hash(document_id, current_file_hash)
        markdown_processor.process_markdown(markdown_file, document_id)

    # Check if a topic title argument is provided
    if args.topic_title:
        # Initialize TopicReader
        topic_reader = TopicReader(db_manager)

        # Retrieve the content for the specified topic
        result = topic_reader.get_topic_content(args.topic_title)

        if result:
            # If content is found, write it back to the original markdown file
            with open(markdown_file, 'w', encoding='utf-8') as file:
                file.write(result)
                file.write('\n')
            print(f"Selected topic and subtopics written to {markdown_file}")
            
            # Generate HTML if --html option is specified
            if args.html:
                html_file = os.path.splitext(markdown_file)[0] + '.html'
                html_content = convert_to_html(result)
                with open(html_file, 'w', encoding='utf-8') as file:
                    file.write(html_content)
                print(f"HTML version written to {html_file}")

            # Update the document hash in the database
            new_file_hash = compute_file_hash(markdown_file)
            document_manager.update_document_hash(document_id, new_file_hash)
        else:
            # If no content is found
            print("No result to write. The original file remains unchanged.")
    else:
        print("No topic title provided. The database has been updated/added without modifying the file.")

        # Generate HTML for the entire document if --html option is specified
        if args.html:
            with open(markdown_file, 'r', encoding='utf-8') as file:
                markdown_content = file.read()
            html_file = os.path.splitext(markdown_file)[0] + '.html'
            html_content = convert_to_html(markdown_content)
            with open(html_file, 'w', encoding='utf-8') as file:
                file.write(html_content)
            print(f"HTML version of the entire document written to {html_file}")
            
    # Close the database connection
    db_manager.close()

if __name__ == '__main__':
    main()