/**
 * Export utilities for match data
 * Provides CSV and JSON export functionality for match listings
 */

import type { MatchListItem } from '$lib/types';
import { formatDuration } from './formatters';

/**
 * Format date to readable string (YYYY-MM-DD HH:MM)
 * @param dateString - ISO date string
 * @returns Formatted date string
 */
function formatDateForExport(dateString: string): string {
	const date = new Date(dateString);
	const year = date.getFullYear();
	const month = String(date.getMonth() + 1).padStart(2, '0');
	const day = String(date.getDate()).padStart(2, '0');
	const hours = String(date.getHours()).padStart(2, '0');
	const minutes = String(date.getMinutes()).padStart(2, '0');
	return `${year}-${month}-${day} ${hours}:${minutes}`;
}

/**
 * Convert matches array to CSV format
 * @param matches - Array of match items to export
 * @returns CSV string
 */
function matchesToCSV(matches: MatchListItem[]): string {
	// CSV Headers
	const headers = [
		'Match ID',
		'Date',
		'Map',
		'Score Team A',
		'Score Team B',
		'Duration',
		'Demo Parsed',
		'Player Count'
	];

	// CSV rows
	const rows = matches.map((match) => {
		return [
			match.match_id,
			formatDateForExport(match.date),
			match.map,
			match.score_team_a.toString(),
			match.score_team_b.toString(),
			formatDuration(match.duration),
			match.demo_parsed ? 'Yes' : 'No',
			match.player_count?.toString() || '-'
		];
	});

	// Combine headers and rows
	const csvContent = [
		headers.join(','),
		...rows.map((row) =>
			row
				.map((cell) => {
					// Escape cells containing commas or quotes
					if (cell.includes(',') || cell.includes('"')) {
						return `"${cell.replace(/"/g, '""')}"`;
					}
					return cell;
				})
				.join(',')
		)
	].join('\n');

	return csvContent;
}

/**
 * Convert matches array to formatted JSON
 * @param matches - Array of match items to export
 * @returns Formatted JSON string
 */
function matchesToJSON(matches: MatchListItem[]): string {
	// Create clean export format
	const exportData = {
		export_date: new Date().toISOString(),
		total_matches: matches.length,
		matches: matches.map((match) => ({
			match_id: match.match_id,
			date: formatDateForExport(match.date),
			map: match.map,
			score: `${match.score_team_a} - ${match.score_team_b}`,
			score_team_a: match.score_team_a,
			score_team_b: match.score_team_b,
			duration: formatDuration(match.duration),
			duration_seconds: match.duration,
			demo_parsed: match.demo_parsed,
			player_count: match.player_count
		}))
	};

	return JSON.stringify(exportData, null, 2);
}

/**
 * Trigger browser download for a file
 * @param content - File content
 * @param filename - Name of file to download
 * @param mimeType - MIME type of file
 */
function triggerDownload(content: string, filename: string, mimeType: string): void {
	const blob = new Blob([content], { type: mimeType });
	const url = URL.createObjectURL(blob);
	const link = document.createElement('a');
	link.href = url;
	link.download = filename;
	document.body.appendChild(link);
	link.click();
	document.body.removeChild(link);
	URL.revokeObjectURL(url);
}

/**
 * Export matches to CSV file
 * Generates and downloads a CSV file with match data
 * @param matches - Array of match items to export
 * @throws Error if matches array is empty
 */
export function exportMatchesToCSV(matches: MatchListItem[]): void {
	if (!matches || matches.length === 0) {
		throw new Error('No matches to export');
	}

	const csvContent = matchesToCSV(matches);
	const timestamp = new Date().toISOString().split('T')[0];
	const filename = `cs2wtf-matches-${timestamp}.csv`;

	triggerDownload(csvContent, filename, 'text/csv;charset=utf-8;');
}

/**
 * Export matches to JSON file
 * Generates and downloads a JSON file with match data
 * @param matches - Array of match items to export
 * @throws Error if matches array is empty
 */
export function exportMatchesToJSON(matches: MatchListItem[]): void {
	if (!matches || matches.length === 0) {
		throw new Error('No matches to export');
	}

	const jsonContent = matchesToJSON(matches);
	const timestamp = new Date().toISOString().split('T')[0];
	const filename = `cs2wtf-matches-${timestamp}.json`;

	triggerDownload(jsonContent, filename, 'application/json;charset=utf-8;');
}