from .tool_utils import (
    ToolError,
    apply_change,
    determine_line_range,
    find_pattern_indices,
    format_tool_result,
    generate_unified_diff_snippet,
    handle_tool_error,
    select_occurrence_index,
    validate_file_for_edit,
)

delete_block_schema = {
    "type": "function",
    "function": {
        "name": "DeleteBlock",
        "description": "Delete a block of lines from a file.",
        "parameters": {
            "type": "object",
            "properties": {
                "file_path": {"type": "string"},
                "start_pattern": {"type": "string"},
                "end_pattern": {"type": "string"},
                "line_count": {"type": "integer"},
                "near_context": {"type": "string"},
                "occurrence": {"type": "integer", "default": 1},
                "change_id": {"type": "string"},
                "dry_run": {"type": "boolean", "default": False},
            },
            "required": ["file_path", "start_pattern"],
        },
    },
}


def _execute_delete_block(
    coder,
    file_path,
    start_pattern,
    end_pattern=None,
    line_count=None,
    near_context=None,
    occurrence=1,
    change_id=None,
    dry_run=False,
):
    """
    Delete a block of text between start_pattern and end_pattern (inclusive).
    Uses utility functions for validation, finding lines, and applying changes.
    """
    tool_name = "DeleteBlock"
    try:
        # 1. Validate file and get content
        abs_path, rel_path, original_content = validate_file_for_edit(coder, file_path)
        lines = original_content.splitlines()

        # 2. Find the start line
        pattern_desc = f"Start pattern '{start_pattern}'"
        if near_context:
            pattern_desc += f" near context '{near_context}'"
        start_pattern_indices = find_pattern_indices(lines, start_pattern, near_context)
        start_line_idx = select_occurrence_index(start_pattern_indices, occurrence, pattern_desc)

        # 3. Determine the end line, passing pattern_desc for better error messages
        start_line, end_line = determine_line_range(
            coder=coder,
            file_path=rel_path,
            lines=lines,
            start_pattern_line_index=start_line_idx,
            end_pattern=end_pattern,
            line_count=line_count,
            target_symbol=None,  # DeleteBlock uses patterns, not symbols
            pattern_desc=pattern_desc,
        )

        # 4. Prepare the deletion
        deleted_lines = lines[start_line : end_line + 1]
        new_lines = lines[:start_line] + lines[end_line + 1 :]
        new_content = "\n".join(new_lines)

        if original_content == new_content:
            coder.io.tool_warning("No changes made: deletion would not change file")
            return "Warning: No changes made (deletion would not change file)"

        # 5. Generate diff for feedback
        diff_snippet = generate_unified_diff_snippet(original_content, new_content, rel_path)
        num_deleted = end_line - start_line + 1
        num_occurrences = len(start_pattern_indices)
        occurrence_str = f"occurrence {occurrence} of " if num_occurrences > 1 else ""

        # 6. Handle dry run
        if dry_run:
            dry_run_message = (
                f"Dry run: Would delete {num_deleted} lines ({start_line + 1}-{end_line + 1}) based"
                f" on {occurrence_str}start pattern '{start_pattern}' in {file_path}."
            )
            return format_tool_result(
                coder,
                tool_name,
                "",
                dry_run=True,
                dry_run_message=dry_run_message,
                diff_snippet=diff_snippet,
            )

        # 7. Apply Change (Not dry run)
        metadata = {
            "start_line": start_line + 1,
            "end_line": end_line + 1,
            "start_pattern": start_pattern,
            "end_pattern": end_pattern,
            "line_count": line_count,
            "near_context": near_context,
            "occurrence": occurrence,
            "deleted_content": "\n".join(deleted_lines),
        }
        final_change_id = apply_change(
            coder,
            abs_path,
            rel_path,
            original_content,
            new_content,
            "deleteblock",
            metadata,
            change_id,
        )

        coder.files_edited_by_tools.add(rel_path)
        # 8. Format and return result, adding line range to success message
        success_message = (
            f"Deleted {num_deleted} lines ({start_line + 1}-{end_line + 1}) (from"
            f" {occurrence_str}start pattern) in {file_path}"
        )
        return format_tool_result(
            coder, tool_name, success_message, change_id=final_change_id, diff_snippet=diff_snippet
        )

    except ToolError as e:
        # Handle errors raised by utility functions (expected errors)
        return handle_tool_error(coder, tool_name, e, add_traceback=False)
    except Exception as e:
        # Handle unexpected errors
        return handle_tool_error(coder, tool_name, e)
