import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import { RefreshCw, XCircle } from "lucide-react";
import {
  Button,
  Dialog,
  DismissibleAlert,
  LoadingFrame,
  StatusBadge,
  type ApiSettings,
} from "@govoplan/core-webui";
import {
  cancelCalendarMigration,
  getCalendarMigration,
  type CalendarMigrationBatch,
} from "../../api/calendar";
import { dateTimeLabel, errorText } from "./calendarViewModel";

export function CalendarMigrationDialog({
  settings,
  batchId,
  onClose,
  onChanged,
}: {
  settings: ApiSettings;
  batchId: string;
  onClose: () => void;
  onChanged: () => void;
}) {
  const [batch, setBatch] = useState<CalendarMigrationBatch | null>(null);
  const [loading, setLoading] = useState(true);
  const [working, setWorking] = useState(false);
  const [error, setError] = useState("");
  const [cancellationEvidence, setCancellationEvidence] = useState("");
  const onChangedRef = useRef(onChanged);
  onChangedRef.current = onChanged;

  const load = useCallback(async () => {
    try {
      const next = await getCalendarMigration(settings, batchId);
      setBatch(next);
      setError("");
      if (next.status === "completed" || next.status === "cancelled") {
        onChangedRef.current();
      }
    } catch (err) {
      setError(errorText(err));
    } finally {
      setLoading(false);
    }
  }, [batchId, settings.accessToken, settings.apiBaseUrl, settings.apiKey]);

  useEffect(() => {
    void load();
  }, [load]);

  useEffect(() => {
    if (!batch || !["active", "blocked", "cancel_requested"].includes(batch.status)) {
      return undefined;
    }
    const timer = window.setInterval(() => void load(), 3000);
    return () => window.clearInterval(timer);
  }, [batch, load]);

  const progress = useMemo(() => {
    if (!batch?.total_resources) return 0;
    const completedSteps = batch.copied_resources + batch.deleted_source_resources;
    return Math.round((completedSteps / (batch.total_resources * 2)) * 100);
  }, [batch]);

  async function cancelMigration() {
    if (!batch?.can_cancel || cancellationEvidence.trim().length < 10) return;
    setWorking(true);
    setError("");
    try {
      const next = await cancelCalendarMigration(
        settings,
        batch.id,
        cancellationEvidence.trim(),
      );
      setBatch(next);
      setCancellationEvidence("");
      onChanged();
    } catch (err) {
      setError(errorText(err));
    } finally {
      setWorking(false);
    }
  }

  return (
    <Dialog
      open
      title="Remote calendar move"
      className="calendar-migration-dialog"
      closeDisabled={working}
      onClose={onClose}
      footer={
        <>
          <Button type="button" onClick={() => void load()} disabled={loading || working}>
            <RefreshCw size={16} /> Refresh
          </Button>
          <Button type="button" onClick={onClose} disabled={working}>Close</Button>
        </>
      }
    >
      {loading && !batch ? (
        <LoadingFrame loading label="Loading remote move"><div /></LoadingFrame>
      ) : (
        <div className="calendar-migration-body">
          {error && (
            <DismissibleAlert tone="danger" resetKey={error}>
              {error}
            </DismissibleAlert>
          )}
          {batch && (
            <>
              <div className="calendar-migration-heading">
                <div>
                  <strong>{phaseLabel(batch.phase)}</strong>
                  <span>Updated {dateTimeLabel(new Date(batch.updated_at))}</span>
                </div>
                <StatusBadge status={batch.status} label={statusLabel(batch.status)} />
              </div>
              <progress value={progress} max={100} aria-label="Remote move progress" />
              <dl className="calendar-migration-summary">
                <div><dt>Events</dt><dd>{batch.total_events}</dd></div>
                <div><dt>Copied</dt><dd>{batch.copied_resources} / {batch.total_resources}</dd></div>
                <div><dt>Source deleted</dt><dd>{batch.deleted_source_resources} / {batch.total_resources}</dd></div>
                <div><dt>Conflicts</dt><dd>{batch.conflict_count}</dd></div>
              </dl>
              {typeof batch.authorization_evidence.note === "string" && (
                <p className="calendar-form-note">
                  Authorization evidence: {batch.authorization_evidence.note}
                </p>
              )}
              {batch.last_error && <p className="calendar-migration-error">{batch.last_error}</p>}
              <ol className="calendar-migration-resources">
                {batch.resources.map((resource) => (
                  <li key={resource.id}>
                    <div>
                      <StatusBadge status={resource.status} label={statusLabel(resource.status)} />
                      <code title={resource.source_href}>{resource.source_href}</code>
                    </div>
                    <span>
                      Copy: {statusLabel(resource.destination_operation_status || "pending")}; source: {statusLabel(resource.source_delete_operation_status || "pending")}
                    </span>
                    {resource.last_error && <p>{resource.last_error}</p>}
                  </li>
                ))}
              </ol>
              {batch.can_cancel && (
                <section className="calendar-migration-cancel">
                  <label>
                    <span>Cancellation evidence</span>
                    <textarea
                      value={cancellationEvidence}
                      onChange={(event) => setCancellationEvidence(event.target.value)}
                      minLength={10}
                      maxLength={2000}
                      rows={3}
                      placeholder="Record why the source must be retained."
                    />
                  </label>
                  <Button
                    type="button"
                    variant="danger"
                    onClick={() => void cancelMigration()}
                    disabled={working || cancellationEvidence.trim().length < 10}
                  >
                    <XCircle size={16} /> Cancel remote move
                  </Button>
                </section>
              )}
            </>
          )}
        </div>
      )}
    </Dialog>
  );
}

function phaseLabel(value: string): string {
  return value.replace(/_/g, " ").replace(/^./, (letter: string) => letter.toUpperCase());
}

function statusLabel(value: string): string {
  return value.replace(/_/g, " ");
}