/**
 *
 * Copyright 2023-2025 InspectorRAGet Team
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 **/

'use client';

import { isEmpty } from 'lodash';
import { useState, useEffect } from 'react';
import { TextArea, Button } from '@carbon/react';
import { WarningAlt } from '@carbon/icons-react';

import { Model, Metric } from '@/src/types';
import {
  PLACHOLDER_EXPRESSION_TEXT,
  validate,
} from '@/src/utilities/expressions';

import classes from './ExpressionBuilder.module.scss';

// ===================================================================================
//                                TYPES
// ===================================================================================
interface Props {
  expression?: object;
  models?: Model[];
  metric?: Metric;
  setExpression?: Function;
}

// ===================================================================================
//                               MAIN FUNCTION
// ===================================================================================
export default function ExpressionBuilder({
  expression,
  models,
  metric,
  setExpression,
}: Props) {
  // Step 1: Initialize state and necessary variables
  const [updatedExpressionText, setUpdatedExpressionText] = useState<string>(
    expression ? JSON.stringify(expression) : PLACHOLDER_EXPRESSION_TEXT,
  );
  const [errorMessage, setErrorMessage] = useState<string>();

  // Step 2: Run effects
  // Step 2.a: Validate expression when updated
  useEffect(() => {
    try {
      // Step 2.a: Check JSON validity
      const updatedExpression = JSON.parse(updatedExpressionText);

      // Step 2.b: Check expression validity
      const errorMessage = validate(
        updatedExpression,
        models?.map((model) => model.modelId),
      );
      if (errorMessage) {
        setErrorMessage(errorMessage);
      } else {
        setErrorMessage(undefined);
      }
    } catch (err) {
      setErrorMessage('Invalid JSON');
    }
  }, [updatedExpressionText]);

  return (
    <div className={classes.page}>
      <TextArea
        labelText="Expression"
        placeholder={JSON.stringify(expression)}
        value={updatedExpressionText}
        disabled={
          models === undefined ||
          metric === undefined ||
          setExpression === undefined
        }
        invalid={errorMessage !== undefined}
        invalidText={errorMessage}
        onChange={(event) => {
          setUpdatedExpressionText(event.target.value);
        }}
        helperText="Please make sure you select correct model ids and values"
        rows={4}
        id="text-area__expression"
      />
      <div className={classes.actionButtons}>
        <Button
          kind="primary"
          disabled={
            errorMessage !== undefined ||
            models === undefined ||
            metric === undefined ||
            setExpression === undefined
          }
          onClick={() =>
            setExpression
              ? setExpression(JSON.parse(updatedExpressionText))
              : () => {}
          }
        >
          Run
        </Button>
        <Button
          kind="secondary"
          disabled={expression === undefined || isEmpty(expression)}
          onClick={() => {
            // Step 1: Reset updated expression text
            setUpdatedExpressionText('{}');

            // Step 2: Reset expression
            if (setExpression) {
              setExpression({});
            }
          }}
        >
          Clear
        </Button>
      </div>

      {models === undefined || metric === undefined ? (
        <div className={classes.containerWarning}>
          <WarningAlt />
          <span>You must select a metric before proceeding.</span>
        </div>
      ) : null}
    </div>
  );
}