import { Search } from "lucide-react";
import { useEffect, useMemo, useState, type FormEvent } from "react";
import {
  Button,
  DocumentationHelpLink,
  DismissibleAlert,
  LoadingIndicator,
  PageScrollViewport,
  StatusBadge,
  i18nMessage,
  useGuardedNavigate,
  type PlatformRouteContext
} from "@govoplan/core-webui";
import {
  listCaseCatalog,
  listCases,
  type CaseCatalog,
  type CaseRecord
} from "../../api/cases";
import { CASES_DOCUMENTATION, CASES_I18N } from "./interfacePatterns";


export default function CasesPage({ settings }: PlatformRouteContext) {
  const navigate = useGuardedNavigate();
  const [query, setQuery] = useState("");
  const [submittedQuery, setSubmittedQuery] = useState("");
  const [status, setStatus] = useState("");
  const [cases, setCases] = useState<CaseRecord[]>([]);
  const [catalog, setCatalog] = useState<CaseCatalog>({ statuses: [], types: [] });
  const [total, setTotal] = useState(0);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState("");

  useEffect(() => {
    const controller = new AbortController();
    setLoading(true);
    setError("");
    Promise.all([
      listCases(settings, {
        query: submittedQuery,
        statuses: status ? [status] : undefined,
        limit: 200
      }, controller.signal),
      listCaseCatalog(settings, controller.signal)
    ]).
      then(([result, nextCatalog]) => {
        setCases(result.cases);
        setTotal(result.total);
        setCatalog(nextCatalog);
      }).
      catch((reason) => {
        if ((reason as Error).name !== "AbortError") {
          setError(reason instanceof Error ? reason.message : "Cases could not be loaded.");
        }
      }).
      finally(() => setLoading(false));
    return () => controller.abort();
  }, [settings, status, submittedQuery]);

  const statusLabels = useMemo(
    () => new Map(catalog.statuses.map((item) => [item.status_key, item])),
    [catalog.statuses]
  );
  const typeLabels = useMemo(
    () => new Map(catalog.types.map((item) => [item.type_key, item.label])),
    [catalog.types]
  );

  function submit(event: FormEvent) {
    event.preventDefault();
    setSubmittedQuery(query.trim());
  }

  return (
    <main className="cases-page">
      <div className="cases-shell">
        <div className="cases-toolbar">
          <form className="cases-search" onSubmit={submit}>
            <Search size={17} aria-hidden="true" />
            <input
              value={query}
              onChange={(event) => setQuery(event.target.value)}
              aria-label="Search cases"
              placeholder="Search cases"
            />
            <Button
              type="submit"
              variant="primary"
              disabledReason={loading ? CASES_I18N.loading : undefined}
            >
              Search
            </Button>
          </form>
          <label className="cases-status-filter">
            <span>Status</span>
            <select value={status} onChange={(event) => setStatus(event.target.value)}>
              <option value="">All statuses</option>
              {catalog.statuses.map((item) =>
                <option key={item.status_key} value={item.status_key}>{item.label}</option>
              )}
            </select>
          </label>
          <span className="cases-count">{i18nMessage("i18n:govoplan-cases.case_count", { value0: total })}</span>
          <DocumentationHelpLink reference={CASES_DOCUMENTATION} />
        </div>
        <PageScrollViewport className="cases-list-viewport">
          {error &&
            <DismissibleAlert tone="error" onDismiss={() => setError("")}>
              {error}
            </DismissibleAlert>
          }
          {loading && <LoadingIndicator label="Loading cases" />}
          {!loading && !error && cases.length === 0 &&
            <div className="cases-empty">No matching cases.</div>
          }
          {!loading && cases.length > 0 &&
            <div className="cases-list" role="list">
              {cases.map((item) => {
                const statusDefinition = statusLabels.get(item.status_key);
                return (
                  <button
                    type="button"
                    className="case-list-row"
                    role="listitem"
                    key={item.reference.object_id}
                    onClick={() => navigate(`/cases/${encodeURIComponent(item.reference.object_id)}`)}>
                    <div className="case-list-primary">
                      <strong>{item.title}</strong>
                      <span>{item.case_number}</span>
                    </div>
                    <span>{typeLabels.get(item.case_type_key) ?? humanize(item.case_type_key)}</span>
                    <span>{formatDate(item.deadline_at)}</span>
                    <StatusBadge
                      status={statusDefinition?.terminal ? "inactive" : "active"}
                      label={statusDefinition?.label ?? humanize(item.status_key)}
                    />
                  </button>
                );
              })}
            </div>
          }
        </PageScrollViewport>
      </div>
    </main>
  );
}

function formatDate(value?: string | null): string {
  return value ? new Intl.DateTimeFormat(undefined, { dateStyle: "medium" }).format(new Date(value)) : "No deadline";
}

function humanize(value: string): string {
  return value.replace(/[_:.\-]+/g, " ").replace(/\b\w/g, (letter) => letter.toUpperCase());
}