school_compare/nextjs-app/components/PerformanceChart.tsx

/**
 * PerformanceChart Component
 * Displays school performance data over time using Chart.js
 */

'use client';

import { Line } from 'react-chartjs-2';
import {
  Chart as ChartJS,
  CategoryScale,
  LinearScale,
  PointElement,
  LineElement,
  Title,
  Tooltip,
  Legend,
  ChartOptions,
} from 'chart.js';
import type { SchoolResult } from '@/lib/types';
import styles from './PerformanceChart.module.css';

// Register Chart.js components
ChartJS.register(
  CategoryScale,
  LinearScale,
  PointElement,
  LineElement,
  Title,
  Tooltip,
  Legend
);

interface PerformanceChartProps {
  data: SchoolResult[];
  schoolName: string;
  isSecondary?: boolean;
}

export function PerformanceChart({ data, schoolName, isSecondary = false }: PerformanceChartProps) {
  // Sort data by year
  const sortedData = [...data].sort((a, b) => a.year - b.year);
  const formatYear = (y: number) => {
    const s = y.toString();
    return s.length === 6 ? `${s.slice(0, 4)}/${s.slice(4)}` : s;
  };
  const years = sortedData.map(d => formatYear(d.year));

  // Prepare datasets — phase-aware
  const datasets = isSecondary ? [
    {
      label: 'Attainment 8',
      data: sortedData.map(d => d.attainment_8_score),
      borderColor: 'rgb(59, 130, 246)',
      backgroundColor: 'rgba(59, 130, 246, 0.1)',
      tension: 0.3,
      yAxisID: 'y',
    },
    {
      label: 'English & Maths Grade 4+',
      data: sortedData.map(d => d.english_maths_standard_pass_pct),
      borderColor: 'rgb(16, 185, 129)',
      backgroundColor: 'rgba(16, 185, 129, 0.1)',
      tension: 0.3,
      yAxisID: 'y',
    },
    {
      label: 'Progress 8',
      data: sortedData.map(d => d.progress_8_score),
      borderColor: 'rgb(245, 158, 11)',
      backgroundColor: 'rgba(245, 158, 11, 0.1)',
      tension: 0.3,
      yAxisID: 'y1',
    },
  ] : [
    {
      label: 'Reading, Writing & Maths Expected %',
      data: sortedData.map(d => d.rwm_expected_pct),
      borderColor: 'rgb(59, 130, 246)',
      backgroundColor: 'rgba(59, 130, 246, 0.1)',
      tension: 0.3,
    },
    {
      label: 'Reading, Writing & Maths Higher %',
      data: sortedData.map(d => d.rwm_high_pct),
      borderColor: 'rgb(16, 185, 129)',
      backgroundColor: 'rgba(16, 185, 129, 0.1)',
      tension: 0.3,
    },
    {
      label: 'Reading Progress',
      data: sortedData.map(d => d.reading_progress),
      borderColor: 'rgb(245, 158, 11)',
      backgroundColor: 'rgba(245, 158, 11, 0.1)',
      tension: 0.3,
      yAxisID: 'y1',
    },
    {
      label: 'Writing Progress',
      data: sortedData.map(d => d.writing_progress),
      borderColor: 'rgb(139, 92, 246)',
      backgroundColor: 'rgba(139, 92, 246, 0.1)',
      tension: 0.3,
      yAxisID: 'y1',
    },
    {
      label: 'Maths Progress',
      data: sortedData.map(d => d.maths_progress),
      borderColor: 'rgb(236, 72, 153)',
      backgroundColor: 'rgba(236, 72, 153, 0.1)',
      tension: 0.3,
      yAxisID: 'y1',
    },
  ];

  const chartData = {
    labels: years,
    datasets,
  };

  const options: ChartOptions<'line'> = {
    responsive: true,
    maintainAspectRatio: false,
    interaction: {
      mode: 'index' as const,
      intersect: false,
    },
    plugins: {
      legend: {
        position: 'top' as const,
        labels: {
          usePointStyle: true,
          padding: 15,
          font: {
            size: 12,
          },
        },
      },
      title: {
        display: true,
        text: `${schoolName} - Performance Over Time`,
        font: {
          size: 16,
          weight: 'bold',
        },
        padding: {
          bottom: 20,
        },
      },
      tooltip: {
        backgroundColor: 'rgba(0, 0, 0, 0.8)',
        padding: 12,
        titleFont: {
          size: 14,
        },
        bodyFont: {
          size: 13,
        },
        callbacks: {
          label: function(context) {
            let label = context.dataset.label || '';
            if (label) {
              label += ': ';
            }
            if (context.parsed.y !== null) {
              if (context.dataset.yAxisID === 'y1') {
                // Progress scores
                label += context.parsed.y.toFixed(1);
              } else {
                // Percentages
                label += context.parsed.y.toFixed(1) + '%';
              }
            }
            return label;
          }
        }
      },
    },
    scales: {
      y: {
        type: 'linear' as const,
        display: true,
        position: 'left' as const,
        title: {
          display: true,
          text: isSecondary ? 'Score / Percentage (%)' : 'Percentage (%)',
          font: {
            size: 12,
            weight: 'bold',
          },
        },
        min: 0,
        max: isSecondary ? undefined : 100,
        grid: {
          color: 'rgba(0, 0, 0, 0.05)',
        },
      },
      y1: {
        type: 'linear' as const,
        display: true,
        position: 'right' as const,
        title: {
          display: true,
          text: isSecondary ? 'Progress 8 Score' : 'Progress Score',
          font: {
            size: 12,
            weight: 'bold',
          },
        },
        grid: {
          drawOnChartArea: false,
        },
      },
      x: {
        grid: {
          display: false,
        },
        title: {
          display: true,
          text: 'Year',
          font: {
            size: 12,
            weight: 'bold',
          },
        },
      },
    },
  };

  return (
    <div className={styles.chartWrapper}>
      <Line data={chartData} options={options} />
    </div>
  );
}