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using System;
using System.Collections.Generic;
using System.Linq;
using XenAdmin.Core;
using XenAdmin.Network;

namespace XenAPI
{
    // Note that the Role object represents both the high-level roles (such as "VM Operator" etc.)
    // and their subroles, i.e., the individual calls they are allowed to make (such as "vm.create").
    public partial class Role
    {
        private static readonly log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
        public const string MR_ROLE_READ_ONLY = "read-only";
        public const string MR_ROLE_VM_OPERATOR = "vm-operator";
        public const string MR_ROLE_VM_ADMIN = "vm-admin";
        public const string MR_ROLE_VM_POWER_ADMIN = "vm-power-admin";
        public const string MR_ROLE_POOL_OPERATOR = "pool-operator";
        public const string MR_ROLE_POOL_ADMIN = "pool-admin";

        public string FriendlyName()
        {
            return FriendlyNameManager.GetFriendlyName($"Role.{name_label.ToLowerInvariant()}.NameLabel");
        }

        public static string FriendlyName(string role)
        {
            return FriendlyNameManager.GetFriendlyName($"Role.{role.ToLowerInvariant()}.NameLabel");
        }

        public string FriendlyDescription()
        {
            return FriendlyNameManager.GetFriendlyName($"Role.{name_label.ToLowerInvariant()}.Description");
        }

        public override string Name()
        {
            return name_label;
        }

        /// <summary>
        /// Currently all RBAC roles can be arranged in a rank so that each one has all the privileges of the next. Use this function for sorting based on this ordering.
        /// </summary>
        private int RoleRank()
        {
            switch (name_label.ToLowerInvariant())
            {
                case MR_ROLE_READ_ONLY: return 0;
                case MR_ROLE_VM_OPERATOR: return 1;
                case MR_ROLE_VM_ADMIN: return 2;
                case MR_ROLE_VM_POWER_ADMIN: return 3;
                case MR_ROLE_POOL_OPERATOR: return 4;
                case MR_ROLE_POOL_ADMIN: return 5;
            }
            return -1;
        }

        /// <summary>
        /// logout, login_with_password
        /// </summary>
        public static readonly RbacMethodList CommonSessionApiList = new RbacMethodList(
            "session.logout", 
            "session.login_with_password"
        );

        /// <summary>
        /// add_to_other_config, destroy
        /// </summary>
        public static readonly RbacMethodList CommonTaskApiList = new RbacMethodList(
            new RbacMethod("task.add_to_other_config", "XenCenterUUID"),  // See AsyncAction.RelatedTask
            new RbacMethod("task.add_to_other_config", "applies_to"),
            new RbacMethod("task.destroy")
        );

        /// <summary>
        /// Takes a list of role objects and returns as a comma separated friendly string.
        /// Note that it excludes xapi internal roles.
        /// </summary>
        public static string FriendlyCsvRoleList(List<Role> roles)
        {
            return roles == null
                ? string.Empty
                : string.Join(", ", roles.Where(r => !r._is_internal).Select(r => r.FriendlyName()));
        }

        /// <summary>
        /// Retrieves all the server RBAC roles which are able to complete all the api methods supplied.
        /// If on George or less this will return an empty list.
        /// </summary>
        /// <param name="apiMethodsToRoleCheck">list of RbacMethods to check</param>
        /// <param name="connection">server connection to retrieve roles from</param>
        public static List<Role> ValidRoleList(RbacMethodList apiMethodsToRoleCheck, IXenConnection connection)
        {
            log.DebugFormat("Checking roles required to complete the following calls: {0}",
                string.Join(", ", apiMethodsToRoleCheck.ToStringArray()));

            var rolesAbleToCompleteAction = new List<Role>();

            foreach (RbacMethod method in apiMethodsToRoleCheck)
            {
                List<Role> rolesAbleToCompleteApiCall = ValidRoleList(method, connection);
                if (rolesAbleToCompleteAction.Count == 0)
                {
                    rolesAbleToCompleteAction.AddRange(rolesAbleToCompleteApiCall);
                    continue;
                }

                //the permissions to run a list of API calls should be those of the
                //most restricted call in the list; if more permissions have been added
                //by the previous calls in the list, these have to be removed

                if (rolesAbleToCompleteApiCall.Count > 0)
                    rolesAbleToCompleteAction.RemoveAll(r => !rolesAbleToCompleteApiCall.Contains(r));
            }

            return rolesAbleToCompleteAction;
        }

        /// <summary>
        /// Retrieves all the server RBAC roles which are able to complete the api method supplied.
        /// If on George or less this will return an empty list.
        /// </summary>
        /// <param name="apiMethodToRoleCheck">RbacMethod to check</param>
        /// <param name="connection">server connection to retrieve roles from</param>
        private static List<Role> ValidRoleList(RbacMethod apiMethodToRoleCheck, IXenConnection connection)
        {
            List<Role> rolesAbleToCompleteApiCall = new List<Role>();
            foreach (Role role in connection.Cache.Roles)
            {
                List<Role> subroles = connection.ResolveAll(role.subroles);
                if (subroles.Find(r => r.CanPerform(apiMethodToRoleCheck)) != null)
                {
                    rolesAbleToCompleteApiCall.Add(role);
                }
            }

            // On connections with roles (i.e. non-simulator connections), each API call
            // should be available to at least Pool Admins (because the latter can do
            // everything). No roles is usually caused by a typo in the apiMethodToRoleCheck,
            // or by running a new action against an old server without checking.

            if (!connection.HostnameWithPort.EndsWith(".xml", StringComparison.InvariantCultureIgnoreCase))
            {
                var msg = $"No roles able to perform API call {apiMethodToRoleCheck}";

                if (rolesAbleToCompleteApiCall.Count < 1)
                    log.Debug(msg);

                System.Diagnostics.Debug.Assert(rolesAbleToCompleteApiCall.Count > 0, msg);
            }

            return rolesAbleToCompleteApiCall;
        }

        /// <summary>
        /// Retrieves all the server RBAC roles which are able to complete the api method supplied.
        /// If on George or less this will return an empty list.
        /// </summary>
        /// <param name="apiMethodToRoleCheck">object.method</param>
        /// <param name="connection">server connection to retrieve roles from</param>
        public static List<Role> ValidRoleList(string apiMethodToRoleCheck, IXenConnection connection)
        {
            return ValidRoleList(new RbacMethod(apiMethodToRoleCheck), connection);
        }

        /// <summary>
        /// Can the main session on this connection already perform all the API methods? If on George or less this will return false.
        /// Also return the list of valid roles.
        /// </summary>
        /// <param name="apiMethodsToRoleCheck">The methods to check</param>
        /// <param name="connection">The connection on which to perform the methods</param>
        /// <param name="validRoleList">The list of roles which can perform all the methods</param>
        public static bool CanPerform(RbacMethodList apiMethodsToRoleCheck, IXenConnection connection, out List<Role> validRoleList)
        {
            if (!connection.IsConnected)
            {
                validRoleList = new List<Role>();
                return false;
            }
            
            validRoleList = ValidRoleList(apiMethodsToRoleCheck, connection);
            
            if (connection.Session != null && connection.Session.IsLocalSuperuser)
                return true;

            foreach (Role role in validRoleList)
            {
                if (connection.Session != null && connection.Session.Roles != null && connection.Session.Roles.Contains(role))
                    return true;
            }
            return false;
        }

        /// <summary>
        /// Can this subrole perform this API call?
        /// </summary>
        /// <param name="rbacMethod">The API call which we want to perform</param>
        private bool CanPerform(RbacMethod rbacMethod)
        {
            // Does the method name match?
            if (name_label == rbacMethod.Method)
                return true;

            // Is the call a hash table modification, and if so, does the
            // more specific name match?
            if (!String.IsNullOrEmpty(rbacMethod.Key))
            {
                string whole = rbacMethod.ToString();
                if (name_label.EndsWith("*"))  // e.g. vm.add_to_other_config/key:Foo*
                {
                    string stripped_name = name_label.TrimEnd('*');
                    if (whole.StartsWith(stripped_name))
                        return true;
                }
                else  // e.g. vm.add_to_other_config/key:Foo
                {
                    if (name_label == whole)
                        return true;
                }
            }

            return false;
        }

        #region XenObjectComparable<Role> Members

        public override int CompareTo(Role other)
        {
            int rank = RoleRank();
            int otherRank = other.RoleRank();
            return rank > otherRank ? 1 : rank < otherRank ? -1 : 0;
        }

        public override bool Equals(object obj)
        {
            return obj is Role r ? r.opaque_ref == opaque_ref : base.Equals(obj);
        }

        public override int GetHashCode()
        {
            return opaque_ref.GetHashCode();
        }

        #endregion
    }
}