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
	{
		List<int> knownRaids;

		public MDStatMonitoringUnit(JsonElement config, RegistersContainer registers) : base(config, registers)
		{
			knownRaids = new List<int>();
			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 []
					int last_pos = lines[i + 1].LastIndexOf(']');
					int pos;
					for (pos = last_pos; pos > 0 && lines[i + 1][pos] != '['; pos--) ;
					if (lines[i + 1][pos] != '[') knownRaids.Add(0);
					else knownRaids.Add(last_pos - pos - 1);
					i += 2;
				}
				else i++;
			}
		}

		public override void GenerateItemsConfig(string name, StringBuilder config)
		{
			for (int i = 0; i < knownRaids.Count; i++)
			{
				for (int j = 0; j < knownRaids[i]; j++)
				{
					config.Append(string.Format("Switch {0}_RAID{1}Disk{2} \"{0} RAID{1} Disk{2} status\" <switch>", name, i, j));
					config.Append(" {channel=\"");
					config.AppendFormat("modbus:data:{0}:{1}:", name, unitName);
					config.AppendFormat("RAID{0}Disk{1}:switch", i, j);
					config.Append("\"}\n");
				}
			}
		}

		public override void GenerateThingsConfig(StringBuilder config)
		{
			int diskAmount = 0;
			foreach (var size in knownRaids) diskAmount += size;
			config.Append("\tBridge poller ");
			config.Append(unitName);
			config.AppendFormat("[start = {0}, length = {1}, type = \"holding\", refresh = 500] {{\n", baseAddress, diskAmount);
			int currentAddress = baseAddress;
			for (int i = 0; i < knownRaids.Count; i++)
			{
				for (int j = 0; j < knownRaids[i]; j++)
				{
					string name = string.Format("RAID{0}Disk{1}", i, j);
					config.Append("\t\tThing data ");
					config.Append(name);
					config.AppendFormat("[readStart = \"{0}\", readValueType = \"int16\"]\n", currentAddress);
					currentAddress++;
				}
			}
			config.Append("\t}\n");
		}

		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;
		}
	}
}