import { useState } from "react";
import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
import {
  Loader2,
  AlertCircle,
  Users,
  Plus,
  X,
  Check,
  UserX,
  UserCheck,
  Edit,
} from "lucide-react";
import { getUsers, createUser, updateUser, type UserOut, type UserCreatePayload } from "../api/users";
import { PasswordPolicyChecklist } from "../components/ChangePasswordModal";

const ROLES = [
  { value: "viewer", label: "Viewer" },
  { value: "red_tech", label: "Red Tech" },
  { value: "blue_tech", label: "Blue Tech" },
  { value: "red_lead", label: "Red Lead" },
  { value: "blue_lead", label: "Blue Lead" },
  { value: "admin", label: "Admin" },
];

const roleBadgeColors: Record<string, string> = {
  admin: "bg-purple-900/50 text-purple-400 border-purple-500/30",
  red_tech: "bg-red-900/50 text-red-400 border-red-500/30",
  blue_tech: "bg-blue-900/50 text-blue-400 border-blue-500/30",
  red_lead: "bg-orange-900/50 text-orange-400 border-orange-500/30",
  blue_lead: "bg-cyan-900/50 text-cyan-400 border-cyan-500/30",
  viewer: "bg-gray-800/50 text-gray-400 border-gray-600/30",
};

export default function UsersPage() {
  const queryClient = useQueryClient();
  const [showCreateModal, setShowCreateModal] = useState(false);
  const [editingUser, setEditingUser] = useState<UserOut | null>(null);

  const {
    data: users,
    isLoading,
    error,
  } = useQuery({
    queryKey: ["users"],
    queryFn: getUsers,
  });

  const createMutation = useMutation({
    mutationFn: createUser,
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ["users"] });
      setShowCreateModal(false);
    },
  });

  const updateMutation = useMutation({
    mutationFn: ({ userId, payload }: { userId: string; payload: Parameters<typeof updateUser>[1] }) =>
      updateUser(userId, payload),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ["users"] });
      setEditingUser(null);
    },
  });

  const toggleUserActive = (user: UserOut) => {
    updateMutation.mutate({
      userId: user.id,
      payload: { is_active: !user.is_active },
    });
  };

  const formatDate = (dateStr: string | null) => {
    if (!dateStr) return "Never";
    return new Date(dateStr).toLocaleDateString("en-US", {
      year: "numeric",
      month: "short",
      day: "numeric",
    });
  };

  if (isLoading) {
    return (
      <div className="flex h-64 items-center justify-center">
        <Loader2 className="h-8 w-8 animate-spin text-cyan-400" />
      </div>
    );
  }

  if (error) {
    return (
      <div className="flex h-64 flex-col items-center justify-center gap-2">
        <AlertCircle className="h-10 w-10 text-red-400" />
        <p className="text-red-400">Failed to load users</p>
      </div>
    );
  }

  return (
    <div className="space-y-6">
      {/* Header */}
      <div className="flex items-center justify-between">
        <div>
          <h1 className="text-2xl font-bold text-white">User Management</h1>
          <p className="mt-1 text-sm text-gray-400">
            Manage user accounts and permissions
          </p>
        </div>
        <button
          onClick={() => setShowCreateModal(true)}
          className="flex items-center gap-1.5 rounded-lg bg-cyan-600 px-4 py-2 text-sm font-medium text-white hover:bg-cyan-500 transition-colors"
        >
          <Plus className="h-4 w-4" />
          New User
        </button>
      </div>

      {/* Users Table */}
      <div className="rounded-xl border border-gray-800 bg-gray-900">
        <div className="overflow-x-auto">
          <table className="w-full text-left text-sm">
            <thead>
              <tr className="border-b border-gray-800">
                <th className="px-6 py-4 font-medium text-gray-400">Username</th>
                <th className="px-6 py-4 font-medium text-gray-400">Email</th>
                <th className="px-6 py-4 font-medium text-gray-400">Role</th>
                <th className="px-6 py-4 font-medium text-gray-400">Status</th>
                <th className="px-6 py-4 font-medium text-gray-400">Created</th>
                <th className="px-6 py-4 font-medium text-gray-400">Last Login</th>
                <th className="px-6 py-4 font-medium text-gray-400">Actions</th>
              </tr>
            </thead>
            <tbody>
              {users?.map((user) => (
                <tr
                  key={user.id}
                  className="border-b border-gray-800/50 hover:bg-gray-800/30 transition-colors"
                >
                  <td className="px-6 py-4">
                    <span className="font-medium text-white">{user.username}</span>
                  </td>
                  <td className="px-6 py-4 text-gray-400">
                    {user.email || "—"}
                  </td>
                  <td className="px-6 py-4">
                    <span
                      className={`inline-flex rounded-full border px-2 py-0.5 text-xs font-medium ${
                        roleBadgeColors[user.role] || roleBadgeColors.viewer
                      }`}
                    >
                      {user.role.replace(/_/g, " ")}
                    </span>
                  </td>
                  <td className="px-6 py-4">
                    {user.is_active ? (
                      <span className="inline-flex items-center gap-1 text-green-400">
                        <Check className="h-3.5 w-3.5" />
                        Active
                      </span>
                    ) : (
                      <span className="inline-flex items-center gap-1 text-red-400">
                        <X className="h-3.5 w-3.5" />
                        Inactive
                      </span>
                    )}
                  </td>
                  <td className="px-6 py-4 text-gray-400">
                    {formatDate(user.created_at)}
                  </td>
                  <td className="px-6 py-4 text-gray-400">
                    {formatDate(user.last_login)}
                  </td>
                  <td className="px-6 py-4">
                    <div className="flex items-center gap-2">
                      <button
                        onClick={() => setEditingUser(user)}
                        className="rounded p-1.5 text-gray-400 hover:bg-gray-800 hover:text-cyan-400"
                        title="Edit user"
                      >
                        <Edit className="h-4 w-4" />
                      </button>
                      <button
                        onClick={() => toggleUserActive(user)}
                        disabled={updateMutation.isPending}
                        className={`rounded p-1.5 ${
                          user.is_active
                            ? "text-gray-400 hover:bg-red-900/50 hover:text-red-400"
                            : "text-gray-400 hover:bg-green-900/50 hover:text-green-400"
                        }`}
                        title={user.is_active ? "Deactivate" : "Activate"}
                      >
                        {user.is_active ? (
                          <UserX className="h-4 w-4" />
                        ) : (
                          <UserCheck className="h-4 w-4" />
                        )}
                      </button>
                    </div>
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
          {users?.length === 0 && (
            <div className="py-12 text-center text-gray-400">
              No users found
            </div>
          )}
        </div>
      </div>

      {/* Create User Modal */}
      {showCreateModal && (
        <CreateUserModal
          onClose={() => setShowCreateModal(false)}
          onSubmit={(data) => createMutation.mutate(data)}
          isSubmitting={createMutation.isPending}
          error={createMutation.error as Error | null}
        />
      )}

      {/* Edit User Modal */}
      {editingUser && (
        <EditUserModal
          user={editingUser}
          onClose={() => setEditingUser(null)}
          onSubmit={(payload) =>
            updateMutation.mutate({ userId: editingUser.id, payload })
          }
          isSubmitting={updateMutation.isPending}
          error={updateMutation.error as Error | null}
        />
      )}
    </div>
  );
}

// ── Create User Modal ──────────────────────────────────────────────

interface CreateUserModalProps {
  onClose: () => void;
  onSubmit: (data: UserCreatePayload) => void;
  isSubmitting: boolean;
  error: Error | null;
}

function CreateUserModal({ onClose, onSubmit, isSubmitting, error }: CreateUserModalProps) {
  const [formData, setFormData] = useState({
    username: "",
    email: "",
    password: "",
    role: "viewer",
  });
  const [errors, setErrors] = useState<Record<string, string>>({});

  const validate = () => {
    const newErrors: Record<string, string> = {};
    if (!formData.username.trim()) newErrors.username = "Username is required";
    if (!formData.password) newErrors.password = "Password is required";
    if (formData.password.length < 6) newErrors.password = "Password must be at least 6 characters";
    setErrors(newErrors);
    return Object.keys(newErrors).length === 0;
  };

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault();
    if (validate()) {
      onSubmit({
        username: formData.username,
        email: formData.email || undefined,
        password: formData.password,
        role: formData.role,
      });
    }
  };

  return (
    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50 backdrop-blur-sm">
      <div className="w-full max-w-md rounded-xl border border-gray-800 bg-gray-900 p-6">
        <div className="flex items-center justify-between mb-4">
          <h3 className="text-lg font-semibold text-white">Create New User</h3>
          <button onClick={onClose} className="text-gray-400 hover:text-white">
            <X className="h-5 w-5" />
          </button>
        </div>

        {error && (
          <div className="mb-4 rounded-lg border border-red-500/30 bg-red-900/20 p-3">
            <p className="text-sm text-red-400">{error.message}</p>
          </div>
        )}

        <form onSubmit={handleSubmit} className="space-y-4">
          <div>
            <label className="block text-sm font-medium text-gray-300">Username *</label>
            <input
              type="text"
              value={formData.username}
              onChange={(e) => setFormData({ ...formData, username: e.target.value })}
              className={`mt-1 w-full rounded-lg border bg-gray-800 px-3 py-2 text-gray-200 ${
                errors.username ? "border-red-500" : "border-gray-700"
              }`}
            />
            {errors.username && <p className="mt-1 text-sm text-red-400">{errors.username}</p>}
          </div>

          <div>
            <label className="block text-sm font-medium text-gray-300">Email</label>
            <input
              type="email"
              value={formData.email}
              onChange={(e) => setFormData({ ...formData, email: e.target.value })}
              className="mt-1 w-full rounded-lg border border-gray-700 bg-gray-800 px-3 py-2 text-gray-200"
            />
          </div>

          <div>
            <label className="block text-sm font-medium text-gray-300">Password *</label>
            <input
              type="password"
              value={formData.password}
              onChange={(e) => setFormData({ ...formData, password: e.target.value })}
              className={`mt-1 w-full rounded-lg border bg-gray-800 px-3 py-2 text-gray-200 ${
                errors.password ? "border-red-500" : "border-gray-700"
              }`}
            />
            <PasswordPolicyChecklist password={formData.password} />
            {errors.password && <p className="mt-1 text-sm text-red-400">{errors.password}</p>}
            <p className="mt-1 text-xs text-amber-400/70">
              The user will be required to change this password on first login.
            </p>
          </div>

          <div>
            <label className="block text-sm font-medium text-gray-300">Role</label>
            <select
              value={formData.role}
              onChange={(e) => setFormData({ ...formData, role: e.target.value })}
              className="mt-1 w-full rounded-lg border border-gray-700 bg-gray-800 px-3 py-2 text-gray-200"
            >
              {ROLES.map((role) => (
                <option key={role.value} value={role.value}>
                  {role.label}
                </option>
              ))}
            </select>
          </div>

          <div className="flex justify-end gap-3 pt-4">
            <button
              type="button"
              onClick={onClose}
              className="rounded-lg border border-gray-700 px-4 py-2 text-sm text-gray-400 hover:bg-gray-800"
            >
              Cancel
            </button>
            <button
              type="submit"
              disabled={isSubmitting}
              className="flex items-center gap-1.5 rounded-lg bg-cyan-600 px-4 py-2 text-sm font-medium text-white hover:bg-cyan-500 disabled:opacity-50"
            >
              {isSubmitting && <Loader2 className="h-4 w-4 animate-spin" />}
              Create User
            </button>
          </div>
        </form>
      </div>
    </div>
  );
}

// ── Edit User Modal ──────────────────────────────────────────────

interface EditUserModalProps {
  user: UserOut;
  onClose: () => void;
  onSubmit: (payload: Parameters<typeof updateUser>[1]) => void;
  isSubmitting: boolean;
  error: Error | null;
}

function EditUserModal({ user, onClose, onSubmit, isSubmitting, error }: EditUserModalProps) {
  const [formData, setFormData] = useState({
    email: user.email || "",
    role: user.role,
    password: "",
  });

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault();
    const payload: Parameters<typeof updateUser>[1] = {
      email: formData.email || undefined,
      role: formData.role,
    };
    if (formData.password) {
      payload.password = formData.password;
    }
    onSubmit(payload);
  };

  return (
    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50 backdrop-blur-sm">
      <div className="w-full max-w-md rounded-xl border border-gray-800 bg-gray-900 p-6">
        <div className="flex items-center justify-between mb-4">
          <h3 className="text-lg font-semibold text-white">Edit User: {user.username}</h3>
          <button onClick={onClose} className="text-gray-400 hover:text-white">
            <X className="h-5 w-5" />
          </button>
        </div>

        {error && (
          <div className="mb-4 rounded-lg border border-red-500/30 bg-red-900/20 p-3">
            <p className="text-sm text-red-400">{error.message}</p>
          </div>
        )}

        <form onSubmit={handleSubmit} className="space-y-4">
          <div>
            <label className="block text-sm font-medium text-gray-300">Email</label>
            <input
              type="email"
              value={formData.email}
              onChange={(e) => setFormData({ ...formData, email: e.target.value })}
              className="mt-1 w-full rounded-lg border border-gray-700 bg-gray-800 px-3 py-2 text-gray-200"
            />
          </div>

          <div>
            <label className="block text-sm font-medium text-gray-300">Role</label>
            <select
              value={formData.role}
              onChange={(e) => setFormData({ ...formData, role: e.target.value })}
              className="mt-1 w-full rounded-lg border border-gray-700 bg-gray-800 px-3 py-2 text-gray-200"
            >
              {ROLES.map((role) => (
                <option key={role.value} value={role.value}>
                  {role.label}
                </option>
              ))}
            </select>
          </div>

          <div>
            <label className="block text-sm font-medium text-gray-300">
              New Password <span className="text-gray-500">(leave blank to keep current)</span>
            </label>
            <input
              type="password"
              value={formData.password}
              onChange={(e) => setFormData({ ...formData, password: e.target.value })}
              className="mt-1 w-full rounded-lg border border-gray-700 bg-gray-800 px-3 py-2 text-gray-200"
              placeholder="••••••••"
            />
            {formData.password.length > 0 && (
              <PasswordPolicyChecklist password={formData.password} />
            )}
          </div>

          <div className="flex justify-end gap-3 pt-4">
            <button
              type="button"
              onClick={onClose}
              className="rounded-lg border border-gray-700 px-4 py-2 text-sm text-gray-400 hover:bg-gray-800"
            >
              Cancel
            </button>
            <button
              type="submit"
              disabled={isSubmitting}
              className="flex items-center gap-1.5 rounded-lg bg-cyan-600 px-4 py-2 text-sm font-medium text-white hover:bg-cyan-500 disabled:opacity-50"
            >
              {isSubmitting && <Loader2 className="h-4 w-4 animate-spin" />}
              Save Changes
            </button>
          </div>
        </form>
      </div>
    </div>
  );
}