from cecli.tools.utils.base_tool import BaseTool
from cecli.tools.utils.helpers 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,
)


class Tool(BaseTool):
    NORM_NAME = "deleteblock"
    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"],
            },
        },
    }

    @classmethod
    def execute(
        cls,
        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})"
                    f" based 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)
