using AS1024.GeoFeed.Models;
using System.Text;

namespace AS1024.GeoFeed.Core.Tools
{
    public static class GeoFeedTools
    {
        /// <summary>
        /// Returns a CSV string for a given GeoFeed retrieved from various sources.
        /// </summary>
        /// <param name="geoFeeds">GeoFeed returned from the source of truth.</param>
        /// <param name="timeStamp">If a timestamp should be appended at the header.</param>
        /// <param name="isCached">If the result is cached.</param>
        /// <returns>CSV formatted string of GeoFeed data.</returns>
        public static string ToGeoFeedCsv(this List<IPGeoFeed> geoFeeds, bool timeStamp = false, bool isCached = false)
        {
            if (geoFeeds == null) throw new ArgumentNullException(nameof(geoFeeds));

            StringBuilder csvContent = new();

            // Append timestamp header if required
            if (timeStamp)
                csvContent.AppendFormat("# GeoFeed generated on {0:R}\n", DateTime.UtcNow);

            // Append cache status if required
            if (isCached)
                csvContent.AppendLine("# Geofeed data is returned from local in memory cache");

            // Iterate over each GeoFeed entry to append its details to the CSV content
            foreach (IPGeoFeed feed in geoFeeds)
            {
                // Using AppendFormat for a cleaner and more readable approach to constructing CSV lines
                csvContent.AppendFormat("{0},{1},{2},{3},{4}\n", feed.Prefix, feed.GeolocCountry, feed.GeolocRegion, feed.GeolocCity, feed.GeolocPostalCode);
            }

            return csvContent.ToString();
        }
    }
}