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

namespace ServerMonitorApp
{
    [DisplayName("Disk space check"), Description("Check the remaining free disk space"), DisplayWeight(11)]
    public class DiskSpaceCheck : SshCheck
    {
        public override string Command => string.Format(DiskSpaceCommand, Device);

        protected string DiskSpaceCommand => "df -P -k {0}";

        public string Device { get; set; }

        public double MinFreeSpace { get; set; }

        public FreeSpaceUnits FreeSpaceUnits { get; set; }

        public DiskSpaceCheck()
        {
            CheckExitCode = true;
            ExitCode = 0;
        }

        protected override List<CheckResult> ProcessCommandResult(string output, int exitCode)
        {
            List<CheckResult> results = base.ProcessCommandResult(output, exitCode);
            if (results.Any(r => r.Failed))
                return results;

            List<string> lines = output.Split('\n').ToList();
            lines.RemoveAt(0);
            if (lines.Count > 1)
            {
                results.Add(Fail("df output was more than one line: " + string.Join("\n", lines)));
            }
            else
            {
                string[] tokens = lines[0].Split(new char[0], StringSplitOptions.RemoveEmptyEntries);
                if (FreeSpaceUnits == FreeSpaceUnits.percent)
                {
                    if (int.TryParse(tokens[4].Replace("%", ""), out int percent))
                    {
                        percent = 100 - percent;
                        string message = string.Format("Free disk space is {0}%", percent);
                        if (percent < MinFreeSpace)
                            results.Add(Fail(message));
                        else
                            results.Add(Pass(message));
                    }
                    else
                    {
                        results.Add(Fail("Unable to parse df output as integer: " + tokens[4].Replace("%", "")));
                    }
                }
                else
                {
                    if (int.TryParse(tokens[3], out int freeSpace))
                    {
                        freeSpace /= 1024;
                        if (FreeSpaceUnits == FreeSpaceUnits.GB)
                            freeSpace /= 1024;
                        string message = string.Format("Free disk space is {0} {1}", freeSpace, FreeSpaceUnits);
                        if (freeSpace < MinFreeSpace)
                            results.Add(Fail(message));
                        else
                            results.Add(Pass(message));
                    }
                    else
                    {
                        results.Add(Fail("Unable to parse df output as integer: " + tokens[3]));
                    }
                }
            }
            return results;
        }

        public override string Validate(bool saving = true)
        {
            string message = base.Validate();
            if (Device.IsNullOrEmpty())
                message += "Device is required." + Environment.NewLine;
            if (MinFreeSpace <= 0)
                message += "Free space must be greater than 0." + Environment.NewLine;
            else if (FreeSpaceUnits == FreeSpaceUnits.percent && MinFreeSpace > 100)
                message += "Free space percent must be between 0 and 100." + Environment.NewLine;
            return message;
        }
    }

    public enum FreeSpaceUnits { MB = 0, GB = 1, percent = 2 }
}