"""
Router — maps a validated intent dict to the correct tool function.

Pure dict lookup, zero overhead. Each tool function has the signature:
    tool(session_id: str, intent: dict) -> dict
and returns {"message": str, "diff": dict}.
"""
from __future__ import annotations

from typing import Callable, Optional

# Import all tools — they register themselves via TOOL_REGISTRY below
from core.a_to_z.student.update import execute_increase, execute_decrease
from core.a_to_z.student.filter_tool import execute_filter
from core.a_to_z.student.sort_tool import execute_sort
from core.a_to_z.student.aggregate import execute_sum, execute_average, execute_count, execute_min, execute_max
from core.a_to_z.student.column_ops import execute_delete_column, execute_rename_column, execute_add_column, execute_cast_type
from core.a_to_z.business.find_replace import execute_find_replace
from core.a_to_z.business.dedup import execute_remove_duplicates


TOOL_MAP: dict[str, Callable[[str, dict], dict]] = {
    # Update
    "increase": execute_increase,
    "decrease": execute_decrease,
    # Filter & Sort
    "filter": execute_filter,
    "sort_asc": execute_sort,
    "sort_desc": execute_sort,
    # Aggregate
    "sum": execute_sum,
    "average": execute_average,
    "count": execute_count,
    "min": execute_min,
    "max": execute_max,
    # Column operations
    "delete_column": execute_delete_column,
    "rename_column": execute_rename_column,
    "add_column": execute_add_column,
    "cast_type": execute_cast_type,
    # Data cleaning
    "find_replace": execute_find_replace,
    "remove_duplicates": execute_remove_duplicates,
}


def dispatch(session_id: str, intent: dict) -> dict:
    """Route intent to the matching tool. Returns tool's result dict."""
    op = intent["operation"]
    tool_fn = TOOL_MAP.get(op)
    if tool_fn is None:
        return {
            "message": f"'{op}' operation supported nahi hai",
            "diff": {},
        }
    return tool_fn(session_id, intent)