/**
 * Chart Management Module
 * Handles Chart.js initialization and updates
 */
class ChartManager {
    constructor(calculator) {
        this.calculator = calculator;
        this.charts = {};
    }

    initializeCharts() {
        // Check if Chart.js is available
        if (typeof Chart === 'undefined') {
            console.error('Chart.js library not loaded. Charts will not be available.');
            this.showChartError('Chart.js library failed to load. Please refresh the page.');
            return;
        }

        try {
            // Instance Growth Chart
            const instanceCanvas = document.getElementById('instanceGrowthChart');
            if (!instanceCanvas) {
                console.error('Instance growth chart canvas not found');
                return;
            }
            const instanceCtx = instanceCanvas.getContext('2d');
            this.charts.instanceGrowth = new Chart(instanceCtx, {
                type: 'line',
                data: { labels: [], datasets: [] },
                options: {
                    responsive: true,
                    maintainAspectRatio: false,
                    plugins: {
                        legend: { position: 'top' }
                    },
                    scales: {
                        y: {
                            beginAtZero: true,
                            title: { display: true, text: 'Total Instances' }
                        },
                        x: {
                            title: { display: true, text: 'Month' }
                        }
                    }
                }
            });

            // Revenue Chart
            const revenueCanvas = document.getElementById('revenueChart');
            if (!revenueCanvas) {
                console.error('Revenue chart canvas not found');
                return;
            }
            const revenueCtx = revenueCanvas.getContext('2d');
            this.charts.revenue = new Chart(revenueCtx, {
                type: 'line',
                data: { labels: [], datasets: [] },
                options: {
                    responsive: true,
                    maintainAspectRatio: false,
                    plugins: {
                        legend: { position: 'top' }
                    },
                    scales: {
                        y: {
                            beginAtZero: true,
                            title: { display: true, text: 'Cumulative Revenue (CHF)' }
                        },
                        x: {
                            title: { display: true, text: 'Month' }
                        }
                    }
                }
            });

            // Cash Flow Chart
            const cashFlowCanvas = document.getElementById('cashFlowChart');
            if (!cashFlowCanvas) {
                console.error('Cash flow chart canvas not found');
                return;
            }
            const cashFlowCtx = cashFlowCanvas.getContext('2d');
            this.charts.cashFlow = new Chart(cashFlowCtx, {
                type: 'bar',
                data: { labels: [], datasets: [] },
                options: {
                    responsive: true,
                    maintainAspectRatio: false,
                    plugins: {
                        legend: { position: 'top' }
                    },
                    scales: {
                        y: {
                            title: { display: true, text: 'Monthly Cash Flow (CHF)' }
                        },
                        x: {
                            title: { display: true, text: 'Month' }
                        }
                    }
                }
            });
        } catch (error) {
            console.error('Error initializing charts:', error);
            this.showChartError('Failed to initialize charts. Please refresh the page.');
        }
    }

    showChartError(message) {
        // Show error message in place of charts
        const chartContainers = ['instanceGrowthChart', 'revenueChart', 'cashFlowChart'];
        chartContainers.forEach(containerId => {
            const container = document.getElementById(containerId);
            if (container) {
                container.style.display = 'flex';
                container.style.justifyContent = 'center';
                container.style.alignItems = 'center';
                container.style.minHeight = '300px';
                container.style.backgroundColor = '#f8f9fa';
                container.style.border = '1px solid #dee2e6';
                container.style.borderRadius = '4px';
                container.innerHTML = `<div class="text-muted text-center"><i class="bi bi-exclamation-triangle"></i><br>${message}</div>`;
            }
        });
    }

    updateCharts() {
        try {
            const scenarios = Object.keys(this.calculator.results);
            if (scenarios.length === 0 || !this.charts.instanceGrowth) return;

            const colors = {
                conservative: '#28a745',
                moderate: '#ffc107',
                aggressive: '#dc3545'
            };

            // Get month labels
            const maxMonths = Math.max(...scenarios.map(s => this.calculator.monthlyData[s].length));
            const monthLabels = Array.from({ length: maxMonths }, (_, i) => `M${i + 1}`);

            // Update Instance Growth Chart
            this.charts.instanceGrowth.data.labels = monthLabels;
            this.charts.instanceGrowth.data.datasets = scenarios.map(scenario => ({
                label: this.calculator.scenarios[scenario].name,
                data: this.calculator.monthlyData[scenario].map(d => d.totalInstances),
                borderColor: colors[scenario],
                backgroundColor: colors[scenario] + '20',
                tension: 0.4
            }));
            this.charts.instanceGrowth.update();

            // Update Revenue Chart
            this.charts.revenue.data.labels = monthLabels;
            this.charts.revenue.data.datasets = scenarios.map(scenario => ({
                label: this.calculator.scenarios[scenario].name + ' (CSP)',
                data: this.calculator.monthlyData[scenario].map(d => d.cumulativeCSPRevenue),
                borderColor: colors[scenario],
                backgroundColor: colors[scenario] + '20',
                tension: 0.4
            }));
            this.charts.revenue.update();

            // Update Cash Flow Chart (show average across scenarios)
            const avgCashFlow = monthLabels.map((_, monthIndex) => {
                const monthData = scenarios.map(scenario =>
                    this.calculator.monthlyData[scenario][monthIndex]?.cspRevenue || 0
                );
                return monthData.reduce((sum, val) => sum + val, 0) / monthData.length;
            });

            this.charts.cashFlow.data.labels = monthLabels;
            this.charts.cashFlow.data.datasets = [{
                label: 'Average Monthly CSP Revenue',
                data: avgCashFlow,
                backgroundColor: '#007bff'
            }];
            this.charts.cashFlow.update();
        } catch (error) {
            console.error('Error updating charts:', error);
        }
    }
}