school_compare/nextjs-app/components/ComparisonView.tsx

/**
 * ComparisonView Component
 * Client-side comparison interface with charts and tables
 */

'use client';

import { useEffect, useState } from 'react';
import { useRouter, usePathname, useSearchParams } from 'next/navigation';
import { useComparison } from '@/hooks/useComparison';
import { ComparisonChart } from './ComparisonChart';
import { SchoolSearchModal } from './SchoolSearchModal';
import { EmptyState } from './EmptyState';
import type { ComparisonData, MetricDefinition } from '@/lib/types';
import { formatPercentage, formatProgress } from '@/lib/utils';
import styles from './ComparisonView.module.css';

interface ComparisonViewProps {
  initialData: Record<string, ComparisonData> | null;
  initialUrns: number[];
  metrics: MetricDefinition[];
  selectedMetric: string;
}

export function ComparisonView({
  initialData,
  initialUrns,
  metrics,
  selectedMetric: initialMetric,
}: ComparisonViewProps) {
  const router = useRouter();
  const pathname = usePathname();
  const searchParams = useSearchParams();
  const { selectedSchools, removeSchool } = useComparison();

  const [selectedMetric, setSelectedMetric] = useState(initialMetric);
  const [isModalOpen, setIsModalOpen] = useState(false);
  const [comparisonData, setComparisonData] = useState(initialData);

  // Sync URL with selected schools
  useEffect(() => {
    const urns = selectedSchools.map((s) => s.urn).join(',');
    const params = new URLSearchParams(searchParams);

    if (urns) {
      params.set('urns', urns);
    } else {
      params.delete('urns');
    }

    params.set('metric', selectedMetric);

    const newUrl = `${pathname}?${params.toString()}`;
    router.replace(newUrl, { scroll: false });

    // Fetch comparison data
    if (selectedSchools.length > 0) {
      fetch(`/api/compare?urns=${urns}`)
        .then((res) => res.json())
        .then((data) => setComparisonData(data.comparison))
        .catch((err) => console.error('Failed to fetch comparison:', err));
    } else {
      setComparisonData(null);
    }
  }, [selectedSchools, selectedMetric, pathname, searchParams, router]);

  const handleMetricChange = (metric: string) => {
    setSelectedMetric(metric);
  };

  const handleRemoveSchool = (urn: number) => {
    removeSchool(urn);
  };

  // Get metric definition
  const currentMetricDef = metrics.find((m) => m.key === selectedMetric);
  const metricLabel = currentMetricDef?.label || selectedMetric;

  // No schools selected
  if (selectedSchools.length === 0) {
    return (
      <div className={styles.container}>
        <header className={styles.header}>
          <h1>Compare Schools</h1>
          <p className={styles.subtitle}>
            Add schools to your comparison basket to see side-by-side performance data
          </p>
        </header>

        <EmptyState
          title="No schools selected"
          message="Add schools from the home page or search to start comparing."
          action={{
            label: 'Browse Schools',
            onClick: () => router.push('/'),
          }}
        />
      </div>
    );
  }

  // Get years for table
  const years =
    comparisonData && Object.keys(comparisonData).length > 0
      ? comparisonData[Object.keys(comparisonData)[0]].yearly_data.map((d) => d.year)
      : [];

  return (
    <div className={styles.container}>
      {/* Header */}
      <header className={styles.header}>
        <div className={styles.headerContent}>
          <div>
            <h1>Compare Schools</h1>
            <p className={styles.subtitle}>
              Comparing {selectedSchools.length} school{selectedSchools.length !== 1 ? 's' : ''}
            </p>
          </div>
          <button onClick={() => setIsModalOpen(true)} className={styles.addButton}>
            + Add School
          </button>
        </div>
      </header>

      {/* Metric Selector */}
      <section className={styles.metricSelector}>
        <label htmlFor="metric-select" className={styles.metricLabel}>
          Select Metric:
        </label>
        <select
          id="metric-select"
          value={selectedMetric}
          onChange={(e) => handleMetricChange(e.target.value)}
          className={styles.metricSelect}
        >
          {metrics.map((metric) => (
            <option key={metric.key} value={metric.key}>
              {metric.label}
            </option>
          ))}
        </select>
      </section>

      {/* School Cards */}
      <section className={styles.schoolsSection}>
        <div className={styles.schoolsGrid}>
          {selectedSchools.map((school) => (
            <div key={school.urn} className={styles.schoolCard}>
              <button
                onClick={() => handleRemoveSchool(school.urn)}
                className={styles.removeButton}
                aria-label="Remove school"
              >
                ×
              </button>
              <h3 className={styles.schoolName}>
                <a href={`/school/${school.urn}`}>{school.school_name}</a>
              </h3>
              <div className={styles.schoolMeta}>
                {school.local_authority && (
                  <span className={styles.metaItem}>{school.local_authority}</span>
                )}
                {school.school_type && (
                  <span className={styles.metaItem}>{school.school_type}</span>
                )}
              </div>

              {/* Latest metric value */}
              {comparisonData && comparisonData[school.urn] && (
                <div className={styles.latestValue}>
                  <div className={styles.latestLabel}>{metricLabel}</div>
                  <div className={styles.latestNumber}>
                    {(() => {
                      const yearlyData = comparisonData[school.urn].yearly_data;
                      if (yearlyData.length === 0) return '-';

                      const latestData = yearlyData[yearlyData.length - 1];
                      const value = latestData[selectedMetric as keyof typeof latestData];

                      if (value === null || value === undefined) return '-';

                      // Format based on metric type
                      if (selectedMetric.includes('progress')) {
                        return formatProgress(value as number);
                      } else if (selectedMetric.includes('pct') || selectedMetric.includes('rate')) {
                        return formatPercentage(value as number);
                      } else {
                        return typeof value === 'number' ? value.toFixed(1) : String(value);
                      }
                    })()}
                  </div>
                </div>
              )}
            </div>
          ))}
        </div>
      </section>

      {/* Comparison Chart */}
      {comparisonData && Object.keys(comparisonData).length > 0 && (
        <section className={styles.chartSection}>
          <h2 className={styles.sectionTitle}>Performance Over Time</h2>
          <div className={styles.chartContainer}>
            <ComparisonChart
              comparisonData={comparisonData}
              metric={selectedMetric}
              metricLabel={metricLabel}
            />
          </div>
        </section>
      )}

      {/* Comparison Table */}
      {comparisonData && Object.keys(comparisonData).length > 0 && years.length > 0 && (
        <section className={styles.tableSection}>
          <h2 className={styles.sectionTitle}>Detailed Comparison</h2>
          <div className={styles.tableWrapper}>
            <table className={styles.comparisonTable}>
              <thead>
                <tr>
                  <th>Year</th>
                  {selectedSchools.map((school) => (
                    <th key={school.urn}>{school.school_name}</th>
                  ))}
                </tr>
              </thead>
              <tbody>
                {years.map((year) => (
                  <tr key={year}>
                    <td className={styles.yearCell}>{year}</td>
                    {selectedSchools.map((school) => {
                      const schoolData = comparisonData[school.urn];
                      if (!schoolData) return <td key={school.urn}>-</td>;

                      const yearData = schoolData.yearly_data.find((d) => d.year === year);
                      if (!yearData) return <td key={school.urn}>-</td>;

                      const value = yearData[selectedMetric as keyof typeof yearData];

                      if (value === null || value === undefined) {
                        return <td key={school.urn}>-</td>;
                      }

                      // Format based on metric type
                      let displayValue: string;
                      if (selectedMetric.includes('progress')) {
                        displayValue = formatProgress(value as number);
                      } else if (selectedMetric.includes('pct') || selectedMetric.includes('rate')) {
                        displayValue = formatPercentage(value as number);
                      } else {
                        displayValue = typeof value === 'number' ? value.toFixed(1) : String(value);
                      }

                      return <td key={school.urn}>{displayValue}</td>;
                    })}
                  </tr>
                ))}
              </tbody>
            </table>
          </div>
        </section>
      )}

      {/* School Search Modal */}
      <SchoolSearchModal isOpen={isModalOpen} onClose={() => setIsModalOpen(false)} />
    </div>
  );
}