"""
Credential scanner and importer for ClaudeTools context import system.

This module provides utilities to scan for credential files, parse structured
credential data from various formats, and import credentials into the database
with automatic encryption.

Security features:
- Automatic encryption using existing credential_service
- No plaintext credentials logged
- Audit trail for all imports
- Support for multiple credential file formats

Supported file formats:
- credentials.md (Markdown format with headers)
- .env (KEY=value format)
- passwords.txt (structured text format)
- Custom parsers for various formats
"""

import logging
import os
import re
from pathlib import Path
from typing import Dict, List, Optional

from sqlalchemy.orm import Session

from api.schemas.credential import CredentialCreate
from api.services.credential_service import create_credential

logger = logging.getLogger(__name__)

# Credential type detection patterns
API_KEY_PATTERNS = [
    r"^sk-[a-zA-Z0-9]{20,}",  # OpenAI-style
    r"^api_[a-zA-Z0-9]{20,}",  # API prefix
    r"^token[_-]?[a-zA-Z0-9]{20,}",  # Token prefix
    r"^ghp_[a-zA-Z0-9]{36,}",  # GitHub Personal Access Token
    r"^gho_[a-zA-Z0-9]{36,}",  # GitHub OAuth Token
    r"^xoxb-[a-zA-Z0-9-]+",  # Slack bot token
    r"^xoxp-[a-zA-Z0-9-]+",  # Slack user token
]

SSH_KEY_PATTERN = r"^-----BEGIN (RSA|OPENSSH|DSA|EC) PRIVATE KEY-----"

CONNECTION_STRING_PATTERNS = [
    r"^(mysql|postgresql|mongodb|redis|mssql)://",
    r"Server=.+;Database=.+;",
    r"Host=.+;Port=\d+;",
]


def scan_for_credential_files(base_path: str) -> List[str]:
    """
    Find all credential files in a directory tree.

    Searches for common credential file names including:
    - credentials.md
    - passwords.txt, passwords.md
    - .env, .env.local, .env.production
    - secrets.txt, secrets.md
    - auth.txt, auth.md

    Args:
        base_path: Root directory to search from

    Returns:
        List of absolute paths to credential files found

    Example:
        ```python
        files = scan_for_credential_files("C:/Projects/MyApp")
        # Returns: ["C:/Projects/MyApp/credentials.md", "C:/Projects/MyApp/.env"]
        ```

    Security:
        - Does not read file contents during scan
        - Only returns file paths for manual review
        - Skips common exclusion patterns (node_modules, .git, etc.)
    """
    credential_files = []
    base_path_obj = Path(base_path)

    # Validate base path exists
    if not base_path_obj.exists():
        logger.warning(f"Base path does not exist: {base_path}")
        return []

    if not base_path_obj.is_dir():
        logger.warning(f"Base path is not a directory: {base_path}")
        return []

    # File name patterns to match
    file_patterns = [
        "credentials.md",
        "credentials.txt",
        "passwords.md",
        "passwords.txt",
        "secrets.md",
        "secrets.txt",
        "auth.md",
        "auth.txt",
        ".env",
        ".env.local",
        ".env.production",
        ".env.development",
        ".env.staging",
    ]

    # Directories to exclude from search
    exclude_dirs = {
        ".git",
        ".svn",
        "node_modules",
        "venv",
        "__pycache__",
        ".venv",
        "dist",
        "build",
        ".pytest_cache",
        ".tox",
    }

    logger.info(f"Scanning for credential files in: {base_path}")

    # Walk directory tree
    for root, dirs, files in os.walk(base_path):
        # Remove excluded directories from search
        dirs[:] = [d for d in dirs if d not in exclude_dirs]

        # Check each file against patterns
        for filename in files:
            if filename in file_patterns:
                file_path = os.path.join(root, filename)
                credential_files.append(file_path)
                logger.info(f"Found credential file: {file_path}")

    logger.info(f"Scan complete. Found {len(credential_files)} credential file(s)")
    return credential_files


def parse_credential_file(file_path: str) -> List[Dict]:
    """
    Extract credentials from a file and return structured data.

    Supports multiple file formats:
    - Markdown (.md) - Parses headers and key-value pairs
    - Environment (.env) - Parses KEY=value format
    - Text (.txt) - Parses structured text with labels

    Args:
        file_path: Absolute path to credential file

    Returns:
        List of credential dictionaries with keys:
        - service_name: Name of the service/system
        - credential_type: Type (password, api_key, oauth, etc.)
        - username: Username (if applicable)
        - password: Password value (if applicable)
        - api_key: API key value (if applicable)
        - token: Token value (if applicable)
        - connection_string: Connection string (if applicable)
        - notes: Additional notes/metadata

    Example:
        ```python
        creds = parse_credential_file("C:/Projects/credentials.md")
        # Returns:
        # [
        #     {
        #         "service_name": "Gitea Admin",
        #         "credential_type": "password",
        #         "username": "admin",
        #         "password": "SecurePass123!"
        #     },
        #     ...
        # ]
        ```

    Security:
        - Returns plaintext credentials for encryption by import function
        - Never logs credential values
        - Validates file exists before reading
    """
    file_path_obj = Path(file_path)

    if not file_path_obj.exists():
        logger.error(f"Credential file not found: {file_path}")
        return []

    if not file_path_obj.is_file():
        logger.error(f"Path is not a file: {file_path}")
        return []

    logger.info(f"Parsing credential file: {file_path}")

    # Determine file type by extension
    file_ext = file_path_obj.suffix.lower()

    try:
        with open(file_path, 'r', encoding='utf-8') as f:
            content = f.read()

        if file_ext == '.md':
            credentials = _parse_markdown_credentials(content)
        elif file_ext == '.env' or file_path_obj.name.startswith('.env'):
            credentials = _parse_env_credentials(content)
        elif file_ext == '.txt':
            credentials = _parse_text_credentials(content)
        else:
            logger.warning(f"Unknown file type: {file_ext}, attempting markdown parser")
            credentials = _parse_markdown_credentials(content)

        logger.info(f"Parsed {len(credentials)} credential(s) from file")
        return credentials

    except Exception as e:
        logger.error(f"Failed to parse credential file: {str(e)}")
        return []


def _parse_markdown_credentials(content: str) -> List[Dict]:
    """
    Parse credentials from Markdown format.

    Expected format:
    ```
    ## Service Name
    Username: user@example.com
    Password: secret123
    API Key: sk-1234567890
    Notes: Additional info

    ## Another Service
    ...
    ```
    """
    credentials = []
    lines = content.split('\n')
    current_cred = None

    for line in lines:
        line = line.strip()

        # Skip empty lines and comments
        if not line or line.startswith('#') and not line.startswith('##'):
            continue

        # Service header (## or #)
        if line.startswith('##'):
            # Save previous credential if exists
            if current_cred and current_cred.get('service_name'):
                credentials.append(_finalize_credential(current_cred))

            # Start new credential
            service_name = line.lstrip('#').strip()
            current_cred = {'service_name': service_name}

        elif line.startswith('#'):
            # Save previous credential if exists
            if current_cred and current_cred.get('service_name'):
                credentials.append(_finalize_credential(current_cred))

            # Start new credential
            service_name = line.lstrip('#').strip()
            current_cred = {'service_name': service_name}

        # Key-value pairs
        elif ':' in line and current_cred is not None:
            key, value = line.split(':', 1)
            key = key.strip().lower()
            value = value.strip()

            if not value:
                continue

            # Map common keys to credential fields
            if key in ['username', 'user', 'login']:
                current_cred['username'] = value
            elif key in ['password', 'pass', 'pwd']:
                current_cred['password'] = value
            elif key in ['api key', 'api_key', 'apikey', 'key']:
                current_cred['api_key'] = value
            elif key in ['token', 'access token', 'access_token', 'bearer']:
                current_cred['token'] = value
            elif key in ['client secret', 'client_secret', 'secret']:
                current_cred['client_secret'] = value
            elif key in ['connection string', 'connection_string', 'conn_str']:
                current_cred['connection_string'] = value
            elif key in ['url', 'host', 'server', 'address']:
                current_cred['url'] = value
            elif key in ['port']:
                try:
                    current_cred['custom_port'] = int(value)
                except ValueError:
                    pass
            elif key in ['notes', 'note', 'description', 'desc']:
                current_cred['notes'] = value
            elif key in ['type', 'credential_type', 'kind']:
                current_cred['credential_type'] = value

    # Add last credential
    if current_cred and current_cred.get('service_name'):
        credentials.append(_finalize_credential(current_cred))

    return credentials


def _parse_env_credentials(content: str) -> List[Dict]:
    """
    Parse credentials from .env format.

    Expected format:
    ```
    DATABASE_URL=mysql://user:pass@host:3306/db
    API_KEY=sk-1234567890
    SECRET_TOKEN=abc123def456
    ```
    """
    credentials = []
    lines = content.split('\n')

    for line in lines:
        line = line.strip()

        # Skip comments and empty lines
        if not line or line.startswith('#'):
            continue

        # Parse KEY=value
        if '=' not in line:
            continue

        key, value = line.split('=', 1)
        key = key.strip()
        value = value.strip().strip('"').strip("'")

        if not value:
            continue

        # Create credential based on key pattern
        cred = {
            'service_name': key.replace('_', ' ').title(),
        }

        # Detect credential type from value
        cred_type, field = _detect_credential_type(value)
        cred['credential_type'] = cred_type
        cred[field] = value

        credentials.append(cred)

    return credentials


def _parse_text_credentials(content: str) -> List[Dict]:
    """
    Parse credentials from structured text format.

    Similar to markdown but more flexible with delimiters.
    """
    # Use markdown parser as fallback for text files
    return _parse_markdown_credentials(content)


def _detect_credential_type(value: str) -> tuple[str, str]:
    """
    Detect the type of credential based on its value pattern.

    Returns:
        tuple: (credential_type, field_name)
    """
    # Check for SSH key
    if re.match(SSH_KEY_PATTERN, value, re.MULTILINE):
        return ('ssh_key', 'password')  # Store in password field

    # Check for API key patterns
    for pattern in API_KEY_PATTERNS:
        if re.match(pattern, value):
            return ('api_key', 'api_key')

    # Check for connection strings
    for pattern in CONNECTION_STRING_PATTERNS:
        if re.match(pattern, value, re.IGNORECASE):
            return ('connection_string', 'connection_string')

    # Check for JWT (basic heuristic: 3 base64 segments separated by dots)
    if value.count('.') == 2 and len(value) > 50:
        parts = value.split('.')
        if all(len(p) > 10 for p in parts):
            return ('jwt', 'token')

    # Check for OAuth token (starts with common prefixes)
    if value.startswith(('ya29.', 'ey', 'oauth')):
        return ('oauth', 'token')

    # Default to password
    return ('password', 'password')


def _finalize_credential(cred: Dict) -> Dict:
    """
    Finalize a credential dictionary by setting defaults and detecting types.
    """
    # Auto-detect credential type if not specified
    if 'credential_type' not in cred:
        if 'api_key' in cred:
            cred['credential_type'] = 'api_key'
        elif 'token' in cred:
            cred['credential_type'] = 'jwt'
        elif 'client_secret' in cred:
            cred['credential_type'] = 'oauth'
        elif 'connection_string' in cred:
            cred['credential_type'] = 'connection_string'
        elif 'password' in cred:
            cred['credential_type'] = 'password'
        else:
            cred['credential_type'] = 'password'

    # Extract URL fields if present
    if 'url' in cred:
        url = cred.pop('url')
        # Determine if internal or external based on IP pattern
        if re.match(r'^(192\.168\.|10\.|172\.(1[6-9]|2[0-9]|3[01])\.)', url):
            cred['internal_url'] = url
        else:
            cred['external_url'] = url

    return cred


def import_credentials_to_db(
    db: Session,
    credentials: List[Dict],
    client_id: Optional[str] = None,
    user_id: str = "system_import",
    ip_address: Optional[str] = None,
) -> int:
    """
    Import credentials into the database using credential_service.

    This function takes a list of credential dictionaries and imports them
    into the database with automatic encryption. Each credential is passed
    through the credential_service which handles:
    - AES-256-GCM encryption of sensitive fields
    - Audit log creation
    - Proper database storage

    Args:
        db: SQLAlchemy database session
        credentials: List of credential dictionaries from parse_credential_file()
        client_id: Optional UUID string to associate credentials with a client
        user_id: User ID for audit logging (default: "system_import")
        ip_address: IP address for audit logging (optional)

    Returns:
        int: Count of successfully imported credentials

    Example:
        ```python
        from api.database import SessionLocal

        db = SessionLocal()
        try:
            files = scan_for_credential_files("C:/Projects")
            for file_path in files:
                creds = parse_credential_file(file_path)
                count = import_credentials_to_db(db, creds, client_id="uuid-here")
                print(f"Imported {count} credentials from {file_path}")
        finally:
            db.close()
        ```

    Security:
        - All sensitive fields automatically encrypted by credential_service
        - Audit log entry created for each import
        - Never logs plaintext credential values
        - Uses existing encryption infrastructure

    Raises:
        Exception: If database operations fail (logged but not raised)
    """
    imported_count = 0

    logger.info(f"Starting import of {len(credentials)} credential(s)")

    for cred_data in credentials:
        try:
            # Add client_id if provided
            if client_id:
                cred_data['client_id'] = client_id

            # Create CredentialCreate schema object
            credential_create = CredentialCreate(**cred_data)

            # Import using credential_service (handles encryption and audit)
            created_credential = create_credential(
                db=db,
                credential_data=credential_create,
                user_id=user_id,
                ip_address=ip_address,
                user_agent="credential_scanner_import",
            )

            imported_count += 1
            logger.info(
                f"Imported credential: {created_credential.service_name} "
                f"(ID: {created_credential.id})"
            )

        except Exception as e:
            logger.error(
                f"Failed to import credential '{cred_data.get('service_name', 'Unknown')}': "
                f"{str(e)}"
            )
            # Continue with next credential instead of failing entire import
            continue

    logger.info(
        f"Import complete. Successfully imported {imported_count}/{len(credentials)} "
        "credential(s)"
    )

    return imported_count


# Convenience function for full workflow
def scan_and_import_credentials(
    base_path: str,
    db: Session,
    client_id: Optional[str] = None,
    user_id: str = "system_import",
    ip_address: Optional[str] = None,
) -> Dict[str, int]:
    """
    Scan for credential files and import all found credentials.

    This is a convenience function that combines scanning, parsing, and importing
    in a single operation.

    Args:
        base_path: Root directory to scan
        db: Database session
        client_id: Optional client UUID to associate credentials with
        user_id: User ID for audit logging
        ip_address: IP address for audit logging

    Returns:
        Dict with summary statistics:
        - files_found: Number of credential files found
        - credentials_parsed: Total credentials parsed from all files
        - credentials_imported: Number successfully imported to database

    Example:
        ```python
        from api.database import SessionLocal

        db = SessionLocal()
        try:
            results = scan_and_import_credentials(
                "C:/Projects/MyClient",
                db,
                client_id="client-uuid-here"
            )
            print(f"Found {results['files_found']} files")
            print(f"Imported {results['credentials_imported']} credentials")
        finally:
            db.close()
        ```
    """
    # Scan for files
    files = scan_for_credential_files(base_path)

    total_parsed = 0
    total_imported = 0

    # Parse and import from each file
    for file_path in files:
        credentials = parse_credential_file(file_path)
        total_parsed += len(credentials)

        if credentials:
            imported = import_credentials_to_db(
                db=db,
                credentials=credentials,
                client_id=client_id,
                user_id=user_id,
                ip_address=ip_address,
            )
            total_imported += imported

    return {
        'files_found': len(files),
        'credentials_parsed': total_parsed,
        'credentials_imported': total_imported,
    }