import { useState, useCallback } from "react";
import type { XOTemplate } from "@xo-cash/types";
import type { VariableInput } from "../types.js";

/**
 * Manages the variable input state for the wizard's variables step.
 *
 * Populates variables from the template's action/role requirements
 * and provides validation + update helpers.
 */
export function useVariableInputs() {
  const [variables, setVariables] = useState<VariableInput[]>([]);

  /**
   * Populate the variable list from the template's role requirements.
   * Calling this again replaces the current variables entirely.
   */
  const initFromTemplate = useCallback(
    (
      template: XOTemplate,
      actionIdentifier: string,
      roleIdentifier: string,
    ) => {
      const action = template.actions?.[actionIdentifier];
      const role = action?.roles?.[roleIdentifier];
      const varIds = role?.requirements?.variables ?? [];

      const varInputs: VariableInput[] = varIds.map((varId) => {
        const varDef = template.variables?.[varId];
        return {
          id: varId,
          name: varDef?.name || varId,
          type: varDef?.type || "string",
          hint: varDef?.hint,
          value: "",
        };
      });
      setVariables(varInputs);
    },
    [],
  );

  /** Update a single variable's value by index. */
  const updateVariable = useCallback((index: number, value: string) => {
    setVariables((prev) => {
      const updated = [...prev];
      const variable = updated[index];
      if (variable) {
        updated[index] = { ...variable, value };
      }
      return updated;
    });
  }, []);

  /** Returns an error message if any required variable is empty, or null if valid. */
  const validate = useCallback((): string | null => {
    const emptyVars = variables.filter(
      (v) => !v.value || v.value.trim() === "",
    );
    if (emptyVars.length > 0) {
      return `Please enter values for: ${emptyVars.map((v) => v.name).join(", ")}`;
    }
    return null;
  }, [variables]);

  return {
    variables,
    setVariables,
    initFromTemplate,
    updateVariable,
    validate,
  } as const;
}

export type VariableInputsState = ReturnType<typeof useVariableInputs>;