using System.Collections.Generic;
using System.Linq;
using System.Security.Claims;
using zero.Core.Extensions;

namespace zero.Core.Identity
{
  public class Permission
  {
    /// <summary>
    /// Full key (stored in left part claim value) of the permission
    /// </summary>
    public string Key { get; set; }

    /// <summary>
    /// Normalized key with optionally removed prefix
    /// </summary>
    public string NormalizedKey { get; set; }

    /// <summary>
    /// Value of the permission (boolean, read/write, ...). Stored in right part of claim value
    /// </summary>
    public string Value { get; set; }

    /// <summary>
    /// Title of this permission for output
    /// </summary>
    public string Label { get; set; }

    /// <summary>
    /// Optional description text
    /// </summary>
    public string Description { get; set; }

    /// <summary>
    /// Datatype of the value
    /// </summary>
    public PermissionValueType ValueType { get; set; }

    /// <summary>
    /// Renders a custom component for this permission in the backoffice
    /// </summary>
    public string CustomComponentPath { get; set; }


    public Permission() { }

    public Permission(string key, string value, PermissionValueType valueType = PermissionValueType.CRUD)
    {
      Key = key;
      Value = value;
      ValueType = valueType;
    }

    public Permission(string key, string label, string description, PermissionValueType valueType = PermissionValueType.CRUD)
    {
      Key = key;
      Label = label;
      Description = description;
      ValueType = valueType;
    }


    /// <summary>
    /// Whether the value is read or write
    /// </summary>
    public bool CanRead => Value == PermissionsValue.Read || Value == PermissionsValue.Update;

    /// <summary>
    /// Whether the value is write
    /// </summary>
    public bool CanWrite => Value == PermissionsValue.Update;

    /// <summary>
    /// Whether the value is true
    /// </summary>
    public bool IsTrue => Value == PermissionsValue.True;

    /// <summary>
    /// Whether the value is false
    /// </summary>
    public bool IsFalse => Value == PermissionsValue.False;

    /// <summary>
    /// Whether a resource (with authorization based on the key) can be read by any of the given permisssions
    /// </summary>
    public static bool CanReadKey(IEnumerable<Permission> permissions, string key, bool isNormalized = false)
    {
      Permission permission = permissions.FirstOrDefault(p => isNormalized ? p.NormalizedKey == key : p.Key == key);
      return permission?.CanRead ?? false;
    }

    /// <summary>
    /// Whether a resource (with authorization based on the key) can be written to by any of the given permisssions
    /// </summary>
    public static bool CanWriteKey(IEnumerable<Permission> permissions, string key, bool isNormalized = false)
    {
      Permission permission = permissions.FirstOrDefault(p => isNormalized ? p.NormalizedKey == key : p.Key == key);
      return permission?.CanWrite ?? false;
    }

    /// <summary>
    /// Create a permission from a claim
    /// </summary>
    public static Permission FromClaim(Claim claim, string prefixToRemove = null)
    {
      if (claim == null)
      {
        return null;
      }
      return FromClaim(claim.Value, prefixToRemove);
    }

    /// <summary>
    /// Create a permission from a claim
    /// </summary>
    public static Permission FromClaim(string claimValue, string prefixToRemove = null)
    {
      Permission permission = new Permission();
      string[] valueParts = claimValue.Split(':');

      permission.Key = valueParts[0];
      permission.NormalizedKey = permission.Key;
      permission.Value = valueParts.Length > 1 ? valueParts[1] : null;

      if (!prefixToRemove.IsNullOrEmpty())
      {
        permission.NormalizedKey = valueParts[0].TrimStart(prefixToRemove);
      }

      return permission;
    }
  }
}