"""EditTool — replace exact string occurrences in a file.

Supports single (unique) replacement or replace-all mode.
"""

from __future__ import annotations

from pathlib import Path
from typing import Any, ClassVar

from ..base import Tool, ToolParameter, ToolResult


class EditTool(Tool):
    """Replace old_string with new_string in a file.

    By default, ``old_string`` must appear exactly once. Set ``replace_all``
    to True to replace every occurrence.
    """

    name: ClassVar[str] = "edit"
    description: ClassVar[str] = (
        "Perform exact string replacement in a file. "
        "Fails if old_string is not found or is ambiguous (unless replace_all is True)."
    )
    parameters: ClassVar[list[ToolParameter]] = [
        ToolParameter(
            name="file_path",
            type="string",
            description="Absolute path to the file to edit",
        ),
        ToolParameter(
            name="old_string",
            type="string",
            description="The exact text to find and replace",
        ),
        ToolParameter(
            name="new_string",
            type="string",
            description="The replacement text",
        ),
        ToolParameter(
            name="replace_all",
            type="boolean",
            description="Replace all occurrences instead of requiring uniqueness",
            required=False,
            default=False,
        ),
    ]

    async def execute(self, **kwargs: Any) -> ToolResult:
        file_path = Path(kwargs["file_path"])
        old_string: str = kwargs["old_string"]
        new_string: str = kwargs["new_string"]
        replace_all: bool = kwargs.get("replace_all", False)

        if not file_path.is_absolute():
            return ToolResult.fail(f"Path must be absolute: {file_path}")

        if not file_path.exists():
            return ToolResult.fail(f"File not found: {file_path}")

        if not file_path.is_file():
            return ToolResult.fail(f"Not a file: {file_path}")

        if old_string == new_string:
            return ToolResult.fail("old_string and new_string are identical")

        try:
            content = file_path.read_text(encoding="utf-8")
        except UnicodeDecodeError:
            return ToolResult.fail(f"Cannot read binary file: {file_path}")
        except PermissionError:
            return ToolResult.fail(f"Permission denied: {file_path}")

        occurrence_count = content.count(old_string)

        if occurrence_count == 0:
            return ToolResult.fail(
                f"old_string not found in {file_path}. "
                "Verify the exact text including whitespace and indentation."
            )

        if not replace_all and occurrence_count > 1:
            return ToolResult.fail(
                f"old_string found {occurrence_count} times in {file_path}. "
                "Provide more context to make it unique, or set replace_all=True."
            )

        if replace_all:
            new_content = content.replace(old_string, new_string)
        else:
            new_content = content.replace(old_string, new_string, 1)

        try:
            file_path.write_text(new_content, encoding="utf-8")
        except PermissionError:
            return ToolResult.fail(f"Permission denied writing to: {file_path}")

        return ToolResult.success(
            f"Replaced {occurrence_count} occurrence(s) in {file_path}",
            file_path=str(file_path),
            replacements=occurrence_count,
        )