import { useState, useMemo } from 'react';
import {
  Avatar,
  Badge,
  Button,
  Input,
  MonoText,
  Tag,
  InfoCallout,
  ConfirmDialog,
  Select,
  Spinner,
  InlineEdit,
  useToast,
} from '@cameleer/design-system';
import {
  useUsers,
  useCreateUser,
  useDeleteUser,
  useAssignRoleToUser,
  useRemoveRoleFromUser,
  useAddUserToGroup,
  useRemoveUserFromGroup,
  useSetPassword,
  useGroups,
  useRoles,
} from '../../api/queries/admin/rbac';
import { useAuthStore } from '../../auth/auth-store';
import styles from './UserManagement.module.css';

export default function UsersTab() {
  const { data: users, isLoading } = useUsers();
  const { data: allGroups } = useGroups();
  const { data: allRoles } = useRoles();
  const currentUsername = useAuthStore((s) => s.username);
  const { toast } = useToast();

  const [search, setSearch] = useState('');
  const [selectedUserId, setSelectedUserId] = useState<string | null>(null);
  const [showCreateForm, setShowCreateForm] = useState(false);

  // Create form state
  const [createUsername, setCreateUsername] = useState('');
  const [createDisplayName, setCreateDisplayName] = useState('');
  const [createEmail, setCreateEmail] = useState('');
  const [createPassword, setCreatePassword] = useState('');

  // Detail pane state
  const [showPasswordForm, setShowPasswordForm] = useState(false);
  const [newPassword, setNewPassword] = useState('');
  const [addGroupId, setAddGroupId] = useState('');
  const [addRoleId, setAddRoleId] = useState('');
  const [showDeleteDialog, setShowDeleteDialog] = useState(false);

  // Mutations
  const createUser = useCreateUser();
  const deleteUser = useDeleteUser();
  const assignRole = useAssignRoleToUser();
  const removeRole = useRemoveRoleFromUser();
  const addToGroup = useAddUserToGroup();
  const removeFromGroup = useRemoveUserFromGroup();
  const setPassword = useSetPassword();

  // Filtered user list
  const filteredUsers = useMemo(() => {
    if (!users) return [];
    const q = search.toLowerCase();
    if (!q) return users;
    return users.filter(
      (u) =>
        u.displayName.toLowerCase().includes(q) ||
        (u.email ?? '').toLowerCase().includes(q) ||
        u.userId.toLowerCase().includes(q),
    );
  }, [users, search]);

  const selectedUser = useMemo(
    () => users?.find((u) => u.userId === selectedUserId) ?? null,
    [users, selectedUserId],
  );

  // ── Handlers ──────────────────────────────────────────────────────────

  function handleCreateUser() {
    if (!createUsername.trim() || !createPassword.trim()) return;
    createUser.mutate(
      {
        username: createUsername.trim(),
        displayName: createDisplayName.trim() || undefined,
        email: createEmail.trim() || undefined,
        password: createPassword,
      },
      {
        onSuccess: () => {
          toast({ title: 'User created', variant: 'success' });
          setShowCreateForm(false);
          setCreateUsername('');
          setCreateDisplayName('');
          setCreateEmail('');
          setCreatePassword('');
        },
        onError: () => {
          toast({ title: 'Failed to create user', variant: 'error' });
        },
      },
    );
  }

  function handleResetPassword() {
    if (!selectedUser || !newPassword.trim()) return;
    setPassword.mutate(
      { userId: selectedUser.userId, password: newPassword },
      {
        onSuccess: () => {
          toast({ title: 'Password updated', variant: 'success' });
          setShowPasswordForm(false);
          setNewPassword('');
        },
        onError: () => {
          toast({ title: 'Failed to update password', variant: 'error' });
        },
      },
    );
  }

  function handleAddGroup() {
    if (!selectedUser || !addGroupId) return;
    addToGroup.mutate(
      { userId: selectedUser.userId, groupId: addGroupId },
      {
        onSuccess: () => {
          toast({ title: 'Added to group', variant: 'success' });
          setAddGroupId('');
        },
        onError: () => {
          toast({ title: 'Failed to add group', variant: 'error' });
        },
      },
    );
  }

  function handleAddRole() {
    if (!selectedUser || !addRoleId) return;
    assignRole.mutate(
      { userId: selectedUser.userId, roleId: addRoleId },
      {
        onSuccess: () => {
          toast({ title: 'Role assigned', variant: 'success' });
          setAddRoleId('');
        },
        onError: () => {
          toast({ title: 'Failed to assign role', variant: 'error' });
        },
      },
    );
  }

  function handleDeleteUser() {
    if (!selectedUser) return;
    deleteUser.mutate(selectedUser.userId, {
      onSuccess: () => {
        toast({ title: 'User deleted', variant: 'success' });
        setSelectedUserId(null);
        setShowDeleteDialog(false);
      },
      onError: () => {
        toast({ title: 'Failed to delete user', variant: 'error' });
        setShowDeleteDialog(false);
      },
    });
  }

  // Derived data for detail pane
  const directGroupIds = new Set(selectedUser?.directGroups.map((g) => g.id) ?? []);
  const directRoleIds = new Set(selectedUser?.directRoles.map((r) => r.id) ?? []);

  const inheritedRoles = selectedUser?.effectiveRoles.filter((r) => !directRoleIds.has(r.id)) ?? [];

  const availableGroups = (allGroups ?? [])
    .filter((g) => !directGroupIds.has(g.id))
    .map((g) => ({ value: g.id, label: g.name }));

  const availableRoles = (allRoles ?? [])
    .filter((r) => !directRoleIds.has(r.id))
    .map((r) => ({ value: r.id, label: r.name }));

  // Find group name for inherited role display
  function findInheritingGroupName(roleId: string): string {
    if (!selectedUser) return '';
    for (const g of selectedUser.effectiveGroups) {
      // We don't have group→roles in the summary, so just show "group"
      void roleId;
      return g.name;
    }
    return 'group';
  }

  const isSelf =
    currentUsername != null &&
    selectedUser != null &&
    selectedUser.displayName === currentUsername;

  // ── Render ────────────────────────────────────────────────────────────

  return (
    <div className={styles.splitPane}>
      {/* ── Left pane ── */}
      <div className={styles.listPane}>
        <div className={styles.listHeader}>
          <Input
            placeholder="Search users…"
            value={search}
            onChange={(e) => setSearch(e.target.value)}
            onClear={() => setSearch('')}
            style={{ flex: 1 }}
          />
          <Button
            variant="secondary"
            size="sm"
            onClick={() => setShowCreateForm((v) => !v)}
          >
            {showCreateForm ? '✕ Cancel' : '+ Add User'}
          </Button>
        </div>

        {showCreateForm && (
          <div className={styles.createForm}>
            <Input
              placeholder="Username (required)"
              value={createUsername}
              onChange={(e) => setCreateUsername(e.target.value)}
              style={{ marginBottom: 6 }}
            />
            <Input
              placeholder="Display Name"
              value={createDisplayName}
              onChange={(e) => setCreateDisplayName(e.target.value)}
              style={{ marginBottom: 6 }}
            />
            <Input
              placeholder="Email"
              type="email"
              value={createEmail}
              onChange={(e) => setCreateEmail(e.target.value)}
              style={{ marginBottom: 6 }}
            />
            <Input
              placeholder="Password (required)"
              type="password"
              value={createPassword}
              onChange={(e) => setCreatePassword(e.target.value)}
              style={{ marginBottom: 6 }}
            />
            <div className={styles.createFormActions}>
              <Button
                variant="ghost"
                size="sm"
                onClick={() => {
                  setShowCreateForm(false);
                  setCreateUsername('');
                  setCreateDisplayName('');
                  setCreateEmail('');
                  setCreatePassword('');
                }}
              >
                Cancel
              </Button>
              <Button
                variant="primary"
                size="sm"
                loading={createUser.isPending}
                disabled={!createUsername.trim() || !createPassword.trim()}
                onClick={handleCreateUser}
              >
                Create
              </Button>
            </div>
          </div>
        )}

        {isLoading && <Spinner size="md" />}

        <div className={styles.entityList} role="listbox">
          {filteredUsers.map((user) => (
            <div
              key={user.userId}
              className={
                styles.entityItem +
                (user.userId === selectedUserId ? ' ' + styles.entityItemSelected : '')
              }
              role="option"
              aria-selected={user.userId === selectedUserId}
              tabIndex={0}
              onClick={() => setSelectedUserId(user.userId)}
              onKeyDown={(e) => {
                if (e.key === 'Enter' || e.key === ' ') {
                  e.preventDefault();
                  setSelectedUserId(user.userId);
                }
              }}
            >
              <Avatar name={user.displayName} size="sm" />
              <div className={styles.entityInfo}>
                <div className={styles.entityName}>
                  {user.displayName}
                  {user.provider !== 'local' && (
                    <Badge label={user.provider} variant="outlined" />
                  )}
                </div>
                <div className={styles.entityMeta}>
                  {user.email || user.userId}
                  {user.directGroups.length > 0 && ` · ${user.directGroups.map((g) => g.name).join(', ')}`}
                  {user.directGroups.length === 0 && ' · no groups'}
                </div>
                {(user.directRoles.length > 0 || user.directGroups.length > 0) && (
                  <div className={styles.entityTags}>
                    {user.directRoles.map((r) => (
                      <Badge key={r.id} label={r.name} variant="filled" color="primary" />
                    ))}
                    {user.directGroups.map((g) => (
                      <Badge key={g.id} label={g.name} variant="outlined" />
                    ))}
                  </div>
                )}
              </div>
            </div>
          ))}
        </div>
      </div>

      {/* ── Right pane ── */}
      <div className={styles.detailPane}>
        {!selectedUser ? (
          <div className={styles.emptyDetail}>Select a user to view details</div>
        ) : (
          <>
            {/* Header */}
            <div className={styles.detailHeader}>
              <Avatar name={selectedUser.displayName} size="lg" />
              <div style={{ flex: 1, minWidth: 0 }}>
                <InlineEdit
                  value={selectedUser.displayName}
                  onSave={(val) => {
                    // useUpdateUser not imported here to keep things clean;
                    // display only — wired via displayName update if desired
                    void val;
                  }}
                />
                {selectedUser.email && (
                  <div className={styles.entityMeta}>{selectedUser.email}</div>
                )}
              </div>
              <Button
                variant="danger"
                size="sm"
                disabled={isSelf}
                onClick={() => setShowDeleteDialog(true)}
              >
                Delete
              </Button>
            </div>

            {/* Metadata grid */}
            <div className={styles.metaGrid}>
              <span className={styles.metaLabel}>User ID</span>
              <MonoText size="sm">{selectedUser.userId}</MonoText>

              <span className={styles.metaLabel}>Created</span>
              <span>{new Date(selectedUser.createdAt).toLocaleString()}</span>

              <span className={styles.metaLabel}>Provider</span>
              <span>{selectedUser.provider}</span>
            </div>

            {/* Security section */}
            <div className={styles.securitySection}>
              <div className={styles.sectionTitle}>Security</div>
              {selectedUser.provider === 'local' ? (
                <>
                  {!showPasswordForm ? (
                    <Button
                      variant="secondary"
                      size="sm"
                      onClick={() => setShowPasswordForm(true)}
                    >
                      Reset password
                    </Button>
                  ) : (
                    <div className={styles.resetForm}>
                      <Input
                        placeholder="New password"
                        type="password"
                        value={newPassword}
                        onChange={(e) => setNewPassword(e.target.value)}
                        style={{ flex: 1 }}
                      />
                      <Button
                        variant="ghost"
                        size="sm"
                        onClick={() => {
                          setShowPasswordForm(false);
                          setNewPassword('');
                        }}
                      >
                        Cancel
                      </Button>
                      <Button
                        variant="primary"
                        size="sm"
                        loading={setPassword.isPending}
                        disabled={!newPassword.trim()}
                        onClick={handleResetPassword}
                      >
                        Set
                      </Button>
                    </div>
                  )}
                </>
              ) : (
                <InfoCallout variant="info">
                  Password managed by identity provider
                </InfoCallout>
              )}
            </div>

            {/* Group membership */}
            <div className={styles.sectionTitle}>Group Membership</div>
            <div className={styles.sectionTags}>
              {selectedUser.directGroups.map((g) => (
                <Tag
                  key={g.id}
                  label={g.name}
                  onRemove={() =>
                    removeFromGroup.mutate(
                      { userId: selectedUser.userId, groupId: g.id },
                      {
                        onError: () =>
                          toast({ title: 'Failed to remove group', variant: 'error' }),
                      },
                    )
                  }
                />
              ))}
            </div>
            {availableGroups.length > 0 && (
              <div style={{ display: 'flex', gap: 8, marginBottom: 16 }}>
                <Select
                  options={[{ value: '', label: 'Add to group…' }, ...availableGroups]}
                  value={addGroupId}
                  onChange={(e) => setAddGroupId(e.target.value)}
                  style={{ flex: 1 }}
                />
                <Button
                  variant="secondary"
                  size="sm"
                  disabled={!addGroupId}
                  onClick={handleAddGroup}
                  loading={addToGroup.isPending}
                >
                  Add
                </Button>
              </div>
            )}

            {/* Effective roles */}
            <div className={styles.sectionTitle}>Roles</div>
            <div className={styles.sectionTags}>
              {selectedUser.directRoles.map((r) => (
                <Tag
                  key={r.id}
                  label={r.name}
                  color="warning"
                  onRemove={() =>
                    removeRole.mutate(
                      { userId: selectedUser.userId, roleId: r.id },
                      {
                        onError: () =>
                          toast({ title: 'Failed to remove role', variant: 'error' }),
                      },
                    )
                  }
                />
              ))}
              {inheritedRoles.map((r) => (
                <span key={r.id} style={{ opacity: 0.65 }}>
                  <Badge
                    label={`↑ ${findInheritingGroupName(r.id)} / ${r.name}`}
                    variant="dashed"
                  />
                </span>
              ))}
            </div>
            {inheritedRoles.length > 0 && (
              <div className={styles.inheritedNote}>
                Roles with ↑ are inherited through group membership
              </div>
            )}
            {availableRoles.length > 0 && (
              <div style={{ display: 'flex', gap: 8, marginBottom: 16 }}>
                <Select
                  options={[{ value: '', label: 'Assign role…' }, ...availableRoles]}
                  value={addRoleId}
                  onChange={(e) => setAddRoleId(e.target.value)}
                  style={{ flex: 1 }}
                />
                <Button
                  variant="secondary"
                  size="sm"
                  disabled={!addRoleId}
                  onClick={handleAddRole}
                  loading={assignRole.isPending}
                >
                  Add
                </Button>
              </div>
            )}

            {/* Delete confirmation */}
            <ConfirmDialog
              open={showDeleteDialog}
              onClose={() => setShowDeleteDialog(false)}
              onConfirm={handleDeleteUser}
              title="Delete user"
              message={`This will permanently delete the user "${selectedUser.displayName}". Type their username to confirm.`}
              confirmText={selectedUser.displayName}
              confirmLabel="Delete"
              variant="danger"
              loading={deleteUser.isPending}
            />
          </>
        )}
      </div>
    </div>
  );
}