using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Delegates.Reports
{
    interface IReporter
    {
        string Caption { get; }
        string BeginList();
        string EndList();
        string MakeCaption(string caption);
        string MakeItem(string valueType, string entry);
    }


    static class Common
    {
        public static object MakeMeanAndStdStatistics(IEnumerable<double> data)
        {
            var newData = data.ToList();
            var mean = newData.Average();
            var std = Math.Sqrt(newData.Select(z => Math.Pow(z - mean, 2)).Sum() / (newData.Count - 1));
            return new MeanAndStd { Mean = mean, Std = std };
        }

        public static object MakeMedianStatistics(IEnumerable<double> data)
        {
            var list = data.OrderBy(z => z).ToList();
            if (list.Count % 2 == 0)
                return (list[list.Count / 2] + list[list.Count / 2 - 1]) / 2;
            return list[list.Count / 2];
        }
    }

	public class HtmlStatistics : IReporter
    {
        public HtmlStatistics(string caption) { Caption = caption; }
        public string Caption { get; }
		public string MakeCaption(string caption) => $"<h1>{caption}</h1>";
		public string BeginList() => "<ul>";
		public string EndList() => "</ul>";
		public string MakeItem(string valueType, string entry) => $"<li><b>{valueType}</b>: {entry}";
	}

	public class MarkdownStatistics : IReporter
    {
        public MarkdownStatistics(string caption) { Caption = caption; }
        public string Caption { get; }
        public string BeginList() => "";
        public string EndList() => "";
        public string MakeCaption(string caption) => $"## {caption}\n\n";
        public string MakeItem(string valueType, string entry) => $" * **{valueType}**: {entry}\n\n";
	}

	public static class ReportMakerHelper
	{
        private static string MakeReport(
            IReporter reporter,
            IEnumerable<Measurement> measurements,
            Func<IEnumerable<double>, object> makeStatistics)
        {
            var data = measurements.ToList();
            var result = new StringBuilder();
            result.Append(reporter.MakeCaption(reporter.Caption));
            result.Append(reporter.BeginList());
            result.Append(reporter.MakeItem("Temperature", makeStatistics(data.Select(z => z.Temperature)).ToString()));
            result.Append(reporter.MakeItem("Humidity", makeStatistics(data.Select(z => z.Humidity)).ToString()));
            result.Append(reporter.EndList());
            return result.ToString();
        }

        public static string MeanAndStdHtmlReport(IEnumerable<Measurement> data) =>
            MakeReport(new HtmlStatistics("Mean and Std"), data, Common.MakeMeanAndStdStatistics);

		public static string MedianMarkdownReport(IEnumerable<Measurement> data) =>
            MakeReport(new MarkdownStatistics("Median"), data, Common.MakeMedianStatistics);

		public static string MeanAndStdMarkdownReport(IEnumerable<Measurement> measurements) =>
            MakeReport(new MarkdownStatistics("Mean and Std"), measurements, Common.MakeMeanAndStdStatistics);

        public static string MedianHtmlReport(IEnumerable<Measurement> measurements)=>
            MakeReport(new HtmlStatistics("Median"), measurements, Common.MakeMedianStatistics);
	}
}