using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Text.Json;
using System.Threading;

namespace Barsik
{
	/// <summary>
	/// Monitors configured RAID array status via /proc/mdstat
	/// Will fill registers info starting from baseAddress with 
	/// disk status (0 - fail, 1 - up) in following order:
	/// raid #0 disk #0
	/// raid #0 disk #1
	/// ...
	/// raid #0 disk #N
	/// raid #1 disk #0
	/// ...
	/// etc
	/// </summary>
	class MDStatMonitoringUnit : BaseMonitoringUnit
	{
		public MDStatMonitoringUnit(JsonElement config, RegistersContainer registers) : base(config, registers)
		{
		}

		public override void Run()
		{
			while (true)
			{
				int currentAddress = baseAddress;
				// the file is not so big, so read it completely
				var lines = File.ReadAllLines("/proc/mdstat");
				for (int i = 0; i < lines.Length;)
				{
					if (lines[i].StartsWith("md") && i < lines.Length - 1)
					{
						// we found device description
						// second line of it is as follows:
						// 2930264896 blocks super 1.0 [2/2] [UU]
						// we need last characters in brackets []
						currentAddress += FillDiskStatus(currentAddress, lines[i + 1]);
						i += 2;
					}
					else i++;
				}
				Thread.Sleep(2000);
			}
		}

		private int FillDiskStatus(int address, string v)
		{
			int last_pos = v.LastIndexOf(']');
			int pos;
			for (pos = last_pos; pos > 0 && v[pos] != '['; pos--) ;
			if (v[pos] != '[') return 0;
			for (int i = pos + 1; i < last_pos; i++)
			{
				if (v[i] == 'U') registers[address + i - (pos + 1)] = 1;
				else registers[address + i - (pos + 1)] = 1;
			}
			return last_pos - pos - 1;
		}
	}
}