"""
File editing tool with find-and-replace functionality.
"""
import difflib
import aiofiles
from pathlib import Path

from src.domains.tools.base import BaseTool, ToolResult
from src.shared.logging import logged, get_logger

logger = get_logger(__name__)

# Binary file extensions to skip
BINARY_EXTENSIONS = {
    '.pyc', '.pyo', '.so', '.o', '.a', '.lib', '.dll', '.exe',
    '.bin', '.dat', '.db', '.sqlite', '.sqlite3',
    '.png', '.jpg', '.jpeg', '.gif', '.ico', '.bmp', '.webp',
    '.pdf', '.doc', '.docx', '.xls', '.xlsx',
    '.zip', '.tar', '.gz', '.bz2', '.7z', '.rar',
    '.mp3', '.mp4', '.avi', '.mov', '.wav',
    '.woff', '.woff2', '.ttf', '.eot',
}


class EditFileTool(BaseTool):
    """
    Edit files using find-and-replace.

    Safely modifies files by finding exact text matches and replacing them.
    Includes safety checks to prevent accidental edits.
    """

    name = "edit_file"
    description = """Make targeted edits to a file using find-and-replace.

Args:
    file_path: Absolute path to the file to edit
    old_string: The exact text to find and replace (must exist in file)
    new_string: The replacement text
    replace_all: If True, replace all occurrences. If False (default),
                 old_string must be unique in the file (appear exactly once).

Returns:
    Success message with diff preview showing changes, or error.

IMPORTANT:
- The old_string must exactly match text in the file (including whitespace/indentation)
- By default, old_string must appear exactly once in the file (for safety)
- Use replace_all=True only when you intentionally want to replace all occurrences
- Always read the file first to verify exact content before editing
- Cannot edit binary files

Examples:
    - Fix a bug: old_string="return x + y", new_string="return x * y"
    - Rename function: old_string="def old_name(", new_string="def new_name("
    - Add import: old_string="import os", new_string="import os\\nimport sys"
"""

    def __init__(
        self,
        allowed_paths: list[str] | None = None,
        max_file_size: int = 1_000_000,  # 1MB
    ):
        """
        Initialize EditFileTool.

        Args:
            allowed_paths: List of allowed directory prefixes (empty = no restrictions)
            max_file_size: Maximum file size to edit in bytes
        """
        self.allowed_paths = allowed_paths or []
        self.max_file_size = max_file_size

    def _is_binary_file(self, path: Path) -> bool:
        """Check if file is likely binary based on extension."""
        return path.suffix.lower() in BINARY_EXTENSIONS

    def _generate_diff(
        self,
        original: str,
        modified: str,
        file_path: str
    ) -> str:
        """Generate a unified diff between original and modified content."""
        original_lines = original.splitlines(keepends=True)
        modified_lines = modified.splitlines(keepends=True)

        diff = difflib.unified_diff(
            original_lines,
            modified_lines,
            fromfile=f"a/{Path(file_path).name}",
            tofile=f"b/{Path(file_path).name}",
            lineterm=""
        )
        return "".join(diff)

    @logged()
    async def execute(
        self,
        file_path: str,
        old_string: str,
        new_string: str,
        replace_all: bool = False
    ) -> ToolResult:
        """
        Edit a file by replacing old_string with new_string.

        Args:
            file_path: Absolute path to the file
            old_string: Text to find (must exist)
            new_string: Replacement text
            replace_all: Replace all occurrences (default: False)

        Returns:
            ToolResult with diff preview or error
        """
        path = Path(file_path)

        # Validate path is allowed
        if not self._validate_path(path, self.allowed_paths):
            return self._error(f"Path not in allowed paths: {file_path}")

        # Check file exists
        if not path.exists():
            return self._error(f"File not found: {file_path}")

        if not path.is_file():
            return self._error(f"Not a file: {file_path}")

        # Check for binary files
        if self._is_binary_file(path):
            return self._error(f"Cannot edit binary file: {file_path}")

        # Check file size
        file_size = path.stat().st_size
        if file_size > self.max_file_size:
            return self._error(
                f"File too large ({file_size} bytes). Max: {self.max_file_size} bytes"
            )

        # Validate inputs
        if not old_string:
            return self._error("old_string cannot be empty")

        if old_string == new_string:
            return self._error("old_string and new_string are identical")

        try:
            # Read file content
            async with aiofiles.open(path, 'r', encoding='utf-8', errors='replace') as f:
                content = await f.read()

            # Check if old_string exists
            count = content.count(old_string)
            if count == 0:
                return self._error(
                    f"old_string not found in file. "
                    f"Make sure to match exact whitespace and indentation."
                )

            # Check uniqueness if replace_all is False
            if not replace_all and count > 1:
                return self._error(
                    f"old_string appears {count} times in file. "
                    f"Use replace_all=True to replace all, or provide a more specific string."
                )

            # Perform replacement
            if replace_all:
                modified = content.replace(old_string, new_string)
            else:
                modified = content.replace(old_string, new_string, 1)

            # Generate diff for preview
            diff = self._generate_diff(content, modified, file_path)

            # Write modified content
            async with aiofiles.open(path, 'w', encoding='utf-8') as f:
                await f.write(modified)

            replacements = count if replace_all else 1
            return self._success(
                data=f"Successfully edited {file_path}\n\n{diff}",
                replacements=replacements,
                file_path=str(path.resolve())
            )

        except PermissionError:
            return self._error(f"Permission denied: {file_path}")
        except UnicodeDecodeError as e:
            return self._error(f"Unable to decode file (binary?): {e}")
        except Exception as e:
            logger.exception(f"Error editing file: {file_path}")
            return self._error(f"Error editing file: {e}")