import { useEffect, useMemo, useState } from "react";
import { Pencil, Plus, Search, Trash2 } from "lucide-react";
import type { ApiSettings } from "@govoplan/core-webui";
import {
  createSystemRole,
  deleteSystemRole,
  fetchPermissionCatalog,
  fetchSystemRoles,
  updateSystemRole,
  type PermissionItem,
  type RoleSummary
} from "../../api/admin";
import { Button } from "@govoplan/core-webui";
import { ConfirmDialog } from "@govoplan/core-webui";
import { DataGrid, type DataGridColumn } from "@govoplan/core-webui";
import { Dialog } from "@govoplan/core-webui";
import { FormField } from "@govoplan/core-webui";
import { StatusBadge } from "@govoplan/core-webui";
import { AdminIconButton, AdminPageLayout, AdminSelectionList, adminErrorMessage, joinLabels } from "@govoplan/core-webui";

const emptyDraft = {
  slug: "",
  name: "",
  description: "",
  permissions: [] as string[],
  isAssignable: true
};

export default function SystemRolesPanel({
  settings,
  canWrite,
  onAuthRefresh
}: {
  settings: ApiSettings;
  canWrite: boolean;
  onAuthRefresh: () => Promise<void>;
}) {
  const [roles, setRoles] = useState<RoleSummary[]>([]);
  const [permissions, setPermissions] = useState<PermissionItem[]>([]);
  const [editing, setEditing] = useState<RoleSummary | "new" | null>(null);
  const [viewing, setViewing] = useState<RoleSummary | null>(null);
  const [deleting, setDeleting] = useState<RoleSummary | null>(null);
  const [draft, setDraft] = useState(emptyDraft);
  const [loading, setLoading] = useState(true);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState("");
  const [success, setSuccess] = useState("");

  async function load() {
    setLoading(true);
    setError("");
    try {
      const [nextRoles, catalogue] = await Promise.all([
        fetchSystemRoles(settings),
        fetchPermissionCatalog(settings)
      ]);
      setRoles(nextRoles);
      setPermissions(catalogue.filter((item) => item.level === "system"));
    } catch (err) {
      setError(adminErrorMessage(err));
    } finally {
      setLoading(false);
    }
  }

  useEffect(() => { void load(); }, [settings.accessToken, settings.apiBaseUrl]);

  function openCreate() {
    setDraft(emptyDraft);
    setEditing("new");
  }

  function openEdit(role: RoleSummary) {
    setDraft({
      slug: role.slug,
      name: role.name,
      description: role.description || "",
      permissions: role.permissions,
      isAssignable: role.is_assignable
    });
    setEditing(role);
  }

  async function save() {
    setBusy(true);
    setError("");
    try {
      if (editing === "new") {
        await createSystemRole(settings, {
          slug: draft.slug,
          name: draft.name,
          description: draft.description || null,
          permissions: draft.permissions
        });
        setSuccess(`System role ${draft.name} created.`);
      } else if (editing) {
        await updateSystemRole(settings, editing.id, {
          name: draft.name,
          description: draft.description || null,
          permissions: draft.permissions,
          is_assignable: draft.isAssignable
        });
        setSuccess(`System role ${draft.name} updated.`);
      }
      setEditing(null);
      await load();
      await onAuthRefresh();
    } catch (err) {
      setError(adminErrorMessage(err));
    } finally {
      setBusy(false);
    }
  }

  async function remove() {
    if (!deleting) return;
    setBusy(true);
    setError("");
    try {
      await deleteSystemRole(settings, deleting.id);
      setSuccess(`System role ${deleting.name} deleted.`);
      setDeleting(null);
      await load();
      await onAuthRefresh();
    } catch (err) {
      setError(adminErrorMessage(err));
    } finally {
      setBusy(false);
    }
  }

  const columns = useMemo<DataGridColumn<RoleSummary>[]>(() => [
    {
      id: "role",
      header: "System role",
      width: 240,
      minWidth: 180,
      maxWidth: 380,
      resizable: true,
      sticky: "start",
      sortable: true,
      filterable: true,
      value: (row) => `${row.name} ${row.slug}`,
      render: (row) => <div><strong>{row.name}</strong><div className="muted small-note">{row.slug}</div></div>
    },
    {
      id: "description",
      header: "Description",
      width: 360,
      fill: true,
      minWidth: 220,
      maxWidth: 640,
      resizable: true,
      sortable: true,
      filterable: true,
      value: (row) => row.description || "",
      render: (row) => row.description || "—"
    },
    {
      id: "permissions",
      header: "Permissions",
      width: 120,
      resizable: false,
      sortable: true,
      filterable: true,
      filterType: "integer",
      value: (row) => row.effective_permission_count,
      render: (row) => String(row.effective_permission_count)
    },
    {
      id: "assignable",
      header: "Assignable",
      width: 120,
      resizable: false,
      sortable: true,
      filterable: true,
      value: (row) => row.is_assignable ? "yes" : "no",
      render: (row) => <StatusBadge status={row.is_assignable ? "active" : "inactive"} label={row.is_assignable ? "Yes" : "No"} />
    },
    {
      id: "assignments",
      header: "Accounts",
      width: 110,
      resizable: false,
      sortable: true,
      filterable: true,
      filterType: "integer",
      value: (row) => row.user_assignments
    },
    {
      id: "actions",
      header: "Actions",
      width: 150,
      sticky: "end",
      resizable: false,
      align: "right",
      render: (row) => {
        const protectedOwner = row.slug === "system_owner";
        return <div className="admin-icon-actions">
          <AdminIconButton label={`Inspect ${row.name}`} icon={<Search />} onClick={() => setViewing(row)} />
          <AdminIconButton label={`Edit ${row.name}`} icon={<Pencil />} onClick={() => openEdit(row)} disabled={!canWrite || protectedOwner} />
          <AdminIconButton label={`Delete ${row.name}`} icon={<Trash2 />} variant="danger" onClick={() => setDeleting(row)} disabled={!canWrite || protectedOwner || row.user_assignments > 0} />
        </div>;
      }
    }
  ], [canWrite]);

  return (
    <>
      <AdminPageLayout
        title="System roles"
        description="Instance-wide role definitions. System owner is protected and indispensable; other system roles are configurable and assigned from System → Users."
        loading={loading}
        error={error}
        success={success}
        actions={<><Button onClick={() => void load()} disabled={loading}>Reload</Button><AdminIconButton label="Add system role" icon={<Plus />} variant="primary" onClick={openCreate} disabled={!canWrite} /></>}
      >
        <div className="admin-table-surface">
          <DataGrid id="admin-system-role-definitions-v4" rows={roles} columns={columns} initialFit="container" getRowKey={(row) => row.id} emptyText="No system roles found." />
        </div>
      </AdminPageLayout>

      <Dialog
        open={editing !== null}
        title={editing === "new" ? "Create system role" : "Edit system role"}
        onClose={() => !busy && setEditing(null)}
        className="admin-dialog admin-dialog-wide"
        footer={<><Button onClick={() => setEditing(null)} disabled={busy}>Cancel</Button><Button variant="primary" onClick={() => void save()} disabled={busy || !draft.name.trim() || !draft.slug.trim()}>{busy ? "Saving…" : "Save role"}</Button></>}
      >
        <div className="admin-form-grid two-columns">
          <FormField label="Name"><input value={draft.name} onChange={(event) => setDraft({ ...draft, name: event.target.value })} /></FormField>
          <FormField label="Slug"><input value={draft.slug} disabled={editing !== "new"} onChange={(event) => setDraft({ ...draft, slug: event.target.value })} /></FormField>
          <FormField label="Assignable"><select value={draft.isAssignable ? "yes" : "no"} onChange={(event) => setDraft({ ...draft, isAssignable: event.target.value === "yes" })}><option value="yes">Yes</option><option value="no">No</option></select></FormField>
          <FormField label="Description"><textarea rows={3} value={draft.description} onChange={(event) => setDraft({ ...draft, description: event.target.value })} /></FormField>
        </div>
        <div className="form-field">
          <span className="form-label">System permissions</span>
          <AdminSelectionList
            options={permissions.filter((permission) => permission.scope !== "system:*").map((permission) => ({ id: permission.scope, label: permission.label, description: permission.description }))}
            selected={draft.permissions}
            onChange={(next) => setDraft({ ...draft, permissions: next })}
          />
          <p className="muted small-note">A role may contain only permissions held by the administrator defining it. The protected system:* wildcard is reserved for System owner.</p>
        </div>
      </Dialog>

      <Dialog open={Boolean(viewing)} title={viewing?.name || "System role details"} onClose={() => setViewing(null)} className="admin-dialog admin-dialog-wide" footer={<Button onClick={() => setViewing(null)}>Close</Button>}>
        {viewing && <dl className="admin-details-grid"><div><dt>Slug</dt><dd>{viewing.slug}</dd></div><div><dt>Protected</dt><dd>{viewing.slug === "system_owner" ? "Yes" : "No"}</dd></div><div><dt>Assignable</dt><dd>{viewing.is_assignable ? "Yes" : "No"}</dd></div><div><dt>Account assignments</dt><dd>{viewing.user_assignments}</dd></div><div><dt>Description</dt><dd>{viewing.description || "—"}</dd></div><div><dt>Effective permissions</dt><dd>{viewing.effective_permission_count}</dd></div><div><dt>Assigned scopes</dt><dd>{viewing.permissions.length ? joinLabels(viewing.permissions.map((name) => ({ name }))) : "—"}</dd></div></dl>}
      </Dialog>

      <ConfirmDialog open={Boolean(deleting)} title="Delete system role" message={`Delete ${deleting?.name}? The role must have no account assignments.`} confirmLabel="Delete role" tone="danger" busy={busy} onCancel={() => setDeleting(null)} onConfirm={() => void remove()} />
    </>
  );
}