using Microsoft.AspNetCore.Identity;
using Sarand.BusinessMgr.Net.Standard.Base.Bus.Control;
using Sarand.Net.Standard.Base.App;
using Sarand.Net.Standard.Base.Utils;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace Sarand.Net.Standard.Base.Helpers
{
	//=======================================================================
	public class SbmcPasswordHelper
	{
		//-------------------------------------------------------------------
		// Configuration parameters.
		public class PasswordParams
		{
			public int MinLength = 8;
			public int MinLengthNoComplexity = 12;
		}
		public static PasswordParams Params { get; } = new PasswordParams();

		//-------------------------------------------------------------------
		/// <summary>Validate password against parameters.</summary>
		public static bool IsValidPassword(String password)
		{
			return GetPasswordStrength(password) >= 4;
		}
		/// <summary>
		/// Assess the password strength - 4+ is valid.
		/// <para>0 - Blank</para>
		/// <para>1 - &lt; min length - 2 [red]</para>
		/// <para>1 - &lt; min length and only 1 character type [red]</para>
		/// <para>2 - &lt; min length and only 2 character types [red]</para>
		/// <para>2 - &lt; min length without complexity - 2 and only 1 character type [red]</para>
		/// <para>3 - &lt; min length, min length with 3 character types [amber]</para>
		/// <para>3 - Min length without complexity - 2 [amber]</para>
		/// <para>3 - Other invalid passwords [amber]</para>
		/// <para>4 - Min length with 4 character types [green]</para>
		/// <para>4 - Min length without complexity [green]</para>
		/// <para>5 - Min lenth + 2 with 4 character types [green]</para>
		/// <para>5 - Min length without complexity with 3 character types [green]</para>
		/// </summary>
		public static int GetPasswordStrength(String password)
		{
			String fn = "PasswordHelper.GetPasswordStrength";

			// 0 - Blank.
			if (StringUtil.IsEmpty(password)) return 0;

			// Count number of different types of character.
			int characterTypeCount = 0;
			try
			{
				if (Regex.Matches(password, "[A-Z]").Count > 0) characterTypeCount++;
				if (Regex.Matches(password, "[a-z]").Count > 0) characterTypeCount++;
				if (Regex.Matches(password, "[0-9]").Count > 0) characterTypeCount++;
				if (Regex.Matches(password, "[^a-zA-Z0-9]").Count > 0) characterTypeCount++;
			}
			catch (Exception exc)
			{
				SaLogger.Debug(fn + " " + ExceptionUtil.GetLogMessage(exc));
			}
			int passwordLength = StringUtil.GetLength(password);

			// 1 - Less than min length - 2;
			if (passwordLength < Params.MinLength - 2)
				return 1;

			// 1 - Less than min length and only 1 character type.
			if (passwordLength < Params.MinLength && characterTypeCount == 1)
				return 1;

			// 2 - Less than min length and only 2 character types.
			if (passwordLength < Params.MinLength && characterTypeCount == 2)
				return 2;

			// 2 - Less than min length without complexity - 2 and only 1 character type.
			if (passwordLength < Params.MinLengthNoComplexity - 2 && characterTypeCount == 1)
				return 2;

			// 3 - Less than minimum length.
			if (passwordLength < Params.MinLength)
				return 3;

			// 3 - Minimum length with only 3 character types.
			if (passwordLength >= Params.MinLength && passwordLength < Params.MinLengthNoComplexity && characterTypeCount == 3)
				return 3;

			// 3 - Minimum length without complexity - 2 with less than 4 character types.
			if (passwordLength >= Params.MinLengthNoComplexity - 2 && passwordLength < Params.MinLengthNoComplexity && characterTypeCount < 4)
				return 3;

			// 3 Catch-all - ensure only valid passwords score 4 or more.
			if (passwordLength < Params.MinLengthNoComplexity && characterTypeCount < 4)
				return 3;

			// 4 - Min length with 4 character types.
			if (passwordLength < Params.MinLengthNoComplexity)
				return 4;

			// 4 - Min length without complexity.
			if (passwordLength >= Params.MinLengthNoComplexity && passwordLength < Params.MinLengthNoComplexity + 2 && characterTypeCount < 4)
				return 4;

			// 5 - Anything more complex.
			return 5;
		}

		//-------------------------------------------------------------------
		private static PasswordHasher<SbmcUserAccount> passwordHasher = new PasswordHasher<SbmcUserAccount>();
		/// <summary>Get the hashed value that corresponds to the password.</summary>
		public static String GetPasswordHash(SbmcUserAccount userAccount, String password)
		{
			return passwordHasher.HashPassword(userAccount, password);
		}
		/// <summary>Verify password against hashed value stored against user account.</summary>
		public static bool VerifyHashedPassword(SbmcUserAccount userAccount, String password)
		{
			return passwordHasher.VerifyHashedPassword(userAccount, userAccount.PasswordHashed, password) != PasswordVerificationResult.Failed;
		}
		/// <summary>Verify password against hashed value with user account as reference.</summary>
		public static bool VerifyHashedPassword(SbmcUserAccount userAccount, String password, String passwordHashed)
		{
			return passwordHasher.VerifyHashedPassword(userAccount, passwordHashed, password) != PasswordVerificationResult.Failed;
		}
		/// <summary>Check whether the password needs rehashing.</summary>
		public static bool PasswordRequiresRehash(SbmcUserAccount userAccount, String password)
		{
			return passwordHasher.VerifyHashedPassword(userAccount, userAccount.PasswordHashed, password) == PasswordVerificationResult.SuccessRehashNeeded;
		}

		//-------------------------------------------------------------------
	}
	//=======================================================================
}