import { useEffect, useMemo, useState } from "react";
import {
  AdminPageLayout,
  adminErrorMessage,
  Button,
  Card,
  DataGrid,
  DismissibleAlert,
  DocumentationHelpLink,
  MetricCard,
  StatusBadge,
  TableActionGroup,
  type ApiSettings,
  type DataGridColumn
} from "@govoplan/core-webui";
import { Play, RefreshCw, RotateCw } from "lucide-react";
import {
  continueSearchRebuild,
  getSearchDiagnostics,
  listSearchProviders,
  processSearchChanges,
  reconcileSearchModules,
  startSearchRebuild,
  type SearchDiagnostics,
  type SearchIndexState,
  type SearchResourceType
} from "../../api/search";

type Props = {
  settings: ApiSettings;
};

type ResourceRow = SearchResourceType & {
  state?: SearchIndexState;
};

const DOCUMENTATION = {
  topicId: "search.global-and-contextual",
  documentationType: "admin" as const
};

export default function SearchAdminPanel({ settings }: Props) {
  const [diagnostics, setDiagnostics] = useState<SearchDiagnostics | null>(null);
  const [resources, setResources] = useState<SearchResourceType[]>([]);
  const [loading, setLoading] = useState(true);
  const [busyKey, setBusyKey] = useState("");
  const [error, setError] = useState("");
  const [success, setSuccess] = useState("");

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

  async function load() {
    setLoading(true);
    setError("");
    try {
      const [nextDiagnostics, catalogue] = await Promise.all([
        getSearchDiagnostics(settings),
        listSearchProviders(settings)
      ]);
      setDiagnostics(nextDiagnostics);
      setResources(catalogue.resources);
    } catch (err) {
      setError(adminErrorMessage(err));
    } finally {
      setLoading(false);
    }
  }

  async function runAction(key: string, action: () => Promise<string>) {
    setBusyKey(key);
    setError("");
    setSuccess("");
    try {
      setSuccess(await action());
      await load();
    } catch (err) {
      setError(adminErrorMessage(err));
    } finally {
      setBusyKey("");
    }
  }

  const rows = useMemo<ResourceRow[]>(() => {
    const states = new Map(
      (diagnostics?.states ?? []).map((state) => [
        `${state.provider_id}:${state.resource_type}`,
        state
      ])
    );
    return resources.map((resource) => ({
      ...resource,
      state: states.get(`${resource.provider_id}:${resource.resource_type}`)
    }));
  }, [diagnostics, resources]);

  const columns = useMemo<DataGridColumn<ResourceRow>[]>(() => [
    {
      id: "resource",
      header: "Search source",
      minWidth: 250,
      resizable: true,
      sortable: true,
      filterable: true,
      value: (row) => row.label,
      render: (row) => (
        <div>
          <strong>{row.label}</strong>
          <div className="muted">{row.module_id} / {row.provider_id}</div>
        </div>
      )
    },
    {
      id: "status",
      header: "State",
      width: 135,
      minWidth: 115,
      sortable: true,
      filterable: true,
      filterType: "list",
      value: (row) => row.state?.status ?? "not built",
      render: (row) => (
        <StatusBadge
          status={statusTone(row.state?.status)}
          label={row.state?.status ?? "not built"}
        />
      )
    },
    {
      id: "documents",
      header: "Documents",
      width: 125,
      minWidth: 105,
      align: "right",
      value: (row) => row.state?.indexed_documents ?? 0
    },
    {
      id: "rejected",
      header: "Rejected",
      width: 105,
      minWidth: 90,
      align: "right",
      value: (row) => row.state?.rejected_documents ?? 0
    },
    {
      id: "lastSuccess",
      header: "Last success",
      width: 190,
      minWidth: 165,
      sortable: true,
      value: (row) => row.state?.last_success_at ?? "",
      render: (row) => formatDateTime(row.state?.last_success_at)
    },
    {
      id: "actions",
      header: "Actions",
      width: 80,
      minWidth: 80,
      sticky: "end",
      align: "right",
      render: (row) => {
        const key = `${row.provider_id}:${row.resource_type}`;
        const continuing = row.state?.status === "backfilling";
        return (
          <TableActionGroup
            minimumSlots={1}
            actions={[{
              id: "rebuild",
              label: continuing ? "Continue bounded rebuild" : "Start clean rebuild",
              icon: continuing ? <Play size={16} /> : <RotateCw size={16} />,
              disabled: Boolean(busyKey),
              onClick: () => void runAction(key, async () => {
                const response = continuing
                  ? await continueSearchRebuild(settings, row.provider_id, row.resource_type)
                  : await startSearchRebuild(settings, row.provider_id, row.resource_type);
                return response.state.status === "backfilling"
                  ? `${row.label} rebuild advanced to the next checkpoint.`
                  : `${row.label} rebuild completed.`;
              })
            }]}
          />
        );
      }
    }
  ], [busyKey, settings]);

  const queue = diagnostics?.queue ?? {};
  const pending = (queue.queued ?? 0) + (queue.retrying ?? 0);
  const quarantined = queue.quarantined ?? 0;

  return (
    <AdminPageLayout
      title="Search index"
      description="Inspect source coverage, process durable changes, and reconcile the tenant's derived index from authoritative modules."
      loading={loading}
      error={error}
      success={success}
      actions={(
        <>
          <Button
            title="Reload search diagnostics"
            aria-label="Reload search diagnostics"
            onClick={() => void load()}
            disabled={loading || Boolean(busyKey)}
          >
            <RefreshCw size={16} />
          </Button>
          <Button
            onClick={() => void runAction("process", async () => {
              const result = await processSearchChanges(settings);
              return `Applied ${result.applied} queued changes; ${result.retrying} remain retryable and ${result.quarantined} were quarantined.`;
            })}
            disabled={Boolean(busyKey)}
          >
            <Play size={16} /> Process queue
          </Button>
          <Button
            onClick={() => void runAction("reconcile", async () => {
              const result = await reconcileSearchModules(settings);
              return `Reconciled active modules: ${result.enabled_documents} enabled and ${result.disabled_documents} disabled documents updated.`;
            })}
            disabled={Boolean(busyKey)}
          >
            <RotateCw size={16} /> Reconcile modules
          </Button>
          <DocumentationHelpLink
            reference={DOCUMENTATION}
            label="Open Search administration documentation"
          />
        </>
      )}
    >
      <div className="metric-grid">
        <MetricCard label="Search sources" value={rows.length} tone="neutral" />
        <MetricCard label="Pending changes" value={pending} tone={pending ? "warning" : "good"} />
        <MetricCard label="Quarantined" value={quarantined} tone={quarantined ? "danger" : "good"} />
        <MetricCard label="Backend" value={diagnostics?.backend ?? "-"} tone="neutral" />
      </div>

      {quarantined > 0 && (
        <DismissibleAlert tone="warning" dismissible={false} compact>
          Quarantined changes require source or contract repair followed by a source rebuild. They are never silently discarded.
        </DismissibleAlert>
      )}

      <Card title="Native source coverage">
        <div className="admin-table-surface">
          <DataGrid
            id="search-index-sources-v1"
            rows={rows}
            columns={columns}
            getRowKey={(row) => `${row.provider_id}:${row.resource_type}`}
            initialFit="container"
            emptyText="No active modules announce searchable resource types."
          />
        </div>
      </Card>

      {rows.some((row) => row.state?.last_error) && (
        <Card title="Latest source errors">
          <div className="settings-list">
            {rows.filter((row) => row.state?.last_error).map((row) => (
              <DismissibleAlert
                key={`${row.provider_id}:${row.resource_type}`}
                tone="warning"
                dismissible={false}
                compact
              >
                <strong>{row.label}:</strong> {row.state?.last_error}
              </DismissibleAlert>
            ))}
          </div>
        </Card>
      )}
    </AdminPageLayout>
  );
}

function statusTone(status?: string): string {
  if (["ready", "idle"].includes(status ?? "")) return "success";
  if (["failed", "quarantined"].includes(status ?? "")) return "danger";
  if (["backfilling", "stale"].includes(status ?? "")) return "warning";
  return "neutral";
}

function formatDateTime(value?: string | null): string {
  if (!value) return "-";
  const parsed = new Date(value);
  return Number.isNaN(parsed.getTime()) ? value : parsed.toLocaleString();
}