/* ============================================================================
   APPLICATIONS AND OPPORTUNITIES - one call
   ----------------------------------------------------------------------------
   /{locale}/applications-and-opportunities/{slug}

   Draft section 8: the detail page carries the application form and the
   acknowledgement ("Thank you for applying to join the SHARP network. Our team
   will review your application and follow up within [X weeks].").

   That "[X weeks]" is marked TBD in the draft and the CMS has no field for it,
   so the number is NEVER named: the acknowledgement says the team will follow
   up by email, and nothing more.

   ROUTE
   Registered in app/routes.ts as "applicationsDetail", a SIBLING of the listing
   route under the ":lang" layout, and typed against its generated `./+types/`
   module.
   ========================================================================= */

import {
  data,
  Form,
  useActionData,
  useLoaderData,
  useNavigation,
} from "react-router";

import { ArrowIcon, Button } from "~/components/ui/Button";
import { Input, Textarea } from "~/components/ui/Input";
import {
  interpolate,
  localizedPath,
  sectionPath,
  toIsoDate,
  translate,
  useTranslation,
} from "~/i18n";
import { safeHref } from "~/lib/safe-href";
import { buildBreadcrumbJsonLd, buildMeta } from "~/lib/seo";
import { isStrapiError, requireEntity } from "~/lib/strapi";

import type { Route } from "./+types/applications-and-opportunities.$slug";
import { getRouteCopy } from "./_events-opportunities/copy";
import {
  FIELD_ERROR_KEYS,
  HONEYPOT_FIELD,
  isHoneypotFilled,
  validateApplication,
  type ApplicationValues,
  type FieldErrors,
} from "./_events-opportunities/forms";
import {
  formatAttachmentMeta,
  formatOpportunityDate,
  opportunityStatusKey,
} from "./_events-opportunities/opportunities";
import { fetchOpportunity } from "./_events-opportunities/opportunities.server";
import { readRootSeo } from "./_events-opportunities/root-seo";
import { submitApplication } from "./_events-opportunities/submissions.server";
import {
  BadgeRow,
  DetailList,
  Notice,
  StatusBadge,
  type DetailItem,
} from "./_events-opportunities/ui";
import {
  detailAlternateDescriptors,
  SELF_ALTERNATES_HANDLE,
} from "./_shared/alternates";
import { requireLocale } from "./_shared/listing";
import { BackLink, PageShell } from "./_shared/listing-ui";
import { RichText } from "./_shared/RichText";

/** This route emits its own canonical + hreflang - see ./_shared/alternates.ts. */
export const handle = SELF_ALTERNATES_HANDLE;

export async function loader({ params }: Route.LoaderArgs) {
  const locale = requireLocale(params.lang);
  const slug = params.slug ?? "";

  const { opportunity, alternates } = requireEntity(
    await fetchOpportunity(slug, locale),
  );

  return { locale, opportunity, alternates };
}

/* ---------------------------------------------------------------------------
   APPLICATION
   ------------------------------------------------------------------------ */

type ActionResult =
  | { readonly ok: true }
  | {
      readonly ok: false;
      readonly errors: FieldErrors;
      readonly values: ApplicationValues;
      /** True when validation passed but the CMS refused the write. */
      readonly failed: boolean;
    };

export async function action({ params, request }: Route.ActionArgs) {
  const locale = requireLocale(params.lang);
  const slug = params.slug ?? "";

  const { opportunity } = requireEntity(await fetchOpportunity(slug, locale));
  const form = await request.formData();

  /* A closed call, or one that is handled elsewhere, has no form on the page
     and must not accept a POST either. */
  if (opportunity.status !== "open" || opportunity.externalApplicationUrl) {
    throw data("This call is not accepting applications", { status: 409 });
  }

  if (isHoneypotFilled(form)) {
    return { ok: true } satisfies ActionResult;
  }

  const { values, errors, valid } = validateApplication(form);

  if (!valid) {
    return data(
      { ok: false, errors, values, failed: false } satisfies ActionResult,
      { status: 400 },
    );
  }

  try {
    await submitApplication({ values, opportunityId: opportunity.documentId });
  } catch (error) {
    if (!isStrapiError(error)) throw error;
    console.error(
      `[opportunities] application for "${slug}" was rejected: ${error.status} ${error.message}`,
    );
    return data(
      { ok: false, errors: {}, values, failed: true } satisfies ActionResult,
      { status: 502 },
    );
  }

  return { ok: true } satisfies ActionResult;
}

/* ---------------------------------------------------------------------------
   META
   ------------------------------------------------------------------------ */

export function meta({ matches, loaderData }: Route.MetaArgs) {
  const root = readRootSeo(matches);
  const result = loaderData as Awaited<ReturnType<typeof loader>> | undefined;
  const copy = getRouteCopy(root.locale);

  if (!result) {
    return buildMeta({
      locale: root.locale,
      pathname: root.pathname,
      siteUrl: root.siteUrl,
      title: copy.opportunities.heading,
      description: copy.opportunities.metaDescription,
    });
  }

  const { opportunity } = result;
  const deadline = opportunity.deadline
    ? translate(root.locale, "opportunities.deadline", {
        date: formatOpportunityDate(opportunity.deadline, root.locale),
      })
    : undefined;

  const descriptors = buildMeta({
    locale: root.locale,
    pathname: root.pathname,
    siteUrl: root.siteUrl,
    title: opportunity.title,
    description:
      opportunity.summary ?? deadline ?? copy.opportunities.metaDescription,
    ...(opportunity.image
      ? { image: { url: opportunity.image.src, alt: opportunity.image.alt } }
      : {}),
    // A closed call stays online for reference, but it should not keep
    // attracting search traffic for an application nobody can make.
    noIndex: opportunity.status === "closed",
    jsonLd: buildBreadcrumbJsonLd(root.siteUrl, [
      {
        name: translate(root.locale, "nav.sections.home"),
        pathname: localizedPath("/", root.locale),
      },
      {
        name: translate(root.locale, "nav.sections.applications"),
        pathname: sectionPath("applications", root.locale),
      },
      { name: opportunity.title, pathname: root.pathname },
    ]),
  });

  return [
    ...descriptors,
    ...detailAlternateDescriptors({
      siteUrl: root.siteUrl,
      section: "applications",
      locale: root.locale,
      slugs: result.alternates,
    }),
  ];
}

/* ---------------------------------------------------------------------------
   PAGE
   ------------------------------------------------------------------------ */

export default function OpportunityDetail() {
  const { opportunity } = useLoaderData<typeof loader>();
  const result = useActionData() as ActionResult | undefined;
  const navigation = useNavigation();
  const { locale, t } = useTranslation();
  const copy = getRouteCopy(locale);

  const listPath = sectionPath("applications", locale);
  const detailPath = `${listPath}/${encodeURIComponent(opportunity.slug)}`;
  const isSubmitting = navigation.state === "submitting";
  const isOpen = opportunity.status === "open";

  const details: DetailItem[] = [
    {
      label: copy.opportunityDetail.statusLabel,
      value: t(opportunityStatusKey(opportunity.status)),
    },
    ...(opportunity.opportunityType
      ? [
          {
            label: copy.opportunityDetail.typeLabel,
            value: copy.opportunityTypes[opportunity.opportunityType],
          },
        ]
      : []),
    ...(opportunity.openDate
      ? [
          {
            label: copy.opportunityDetail.opensLabel,
            value: (
              <time dateTime={toIsoDate(opportunity.openDate)}>
                {formatOpportunityDate(opportunity.openDate, locale)}
              </time>
            ),
          },
        ]
      : []),
    ...(opportunity.deadline
      ? [
          {
            label: copy.opportunityDetail.deadlineLabel,
            value: (
              <time dateTime={toIsoDate(opportunity.deadline)}>
                {formatOpportunityDate(opportunity.deadline, locale)}
              </time>
            ),
          },
        ]
      : []),
  ];

  return (
    <PageShell>
      <BackLink to={listPath} label={copy.opportunityDetail.backToList} />

      <header className="flex max-w-[var(--layout-prose-max)] flex-col gap-md">
        <BadgeRow>
          <StatusBadge tone={isOpen ? "accent" : "neutral"}>
            {t(opportunityStatusKey(opportunity.status))}
          </StatusBadge>
          {opportunity.opportunityType ? (
            <StatusBadge>
              {copy.opportunityTypes[opportunity.opportunityType]}
            </StatusBadge>
          ) : null}
        </BadgeRow>

        <h1 className="display-sm text-text-primary">{opportunity.title}</h1>

        {opportunity.summary ? (
          <p className="body-lg text-text-secondary">{opportunity.summary}</p>
        ) : null}
      </header>

      <div className="flex flex-col gap-2xl lg:flex-row lg:items-start">
        <div className="flex min-w-0 flex-1 flex-col gap-lg">
          {opportunity.description ? (
            <section
              aria-labelledby="opportunity-about"
              className="flex flex-col gap-md"
            >
              <h2
                id="opportunity-about"
                className="heading-h2 text-text-primary"
              >
                {copy.opportunityDetail.aboutHeading}
              </h2>
              <RichText value={opportunity.description} />
            </section>
          ) : null}

          {opportunity.eligibility ? (
            <section
              aria-labelledby="opportunity-eligibility"
              className="flex flex-col gap-md"
            >
              <h2
                id="opportunity-eligibility"
                className="heading-h3 text-text-primary"
              >
                {t("opportunities.eligibility")}
              </h2>
              <RichText value={opportunity.eligibility} />
            </section>
          ) : null}

          {opportunity.howToApply ? (
            <section
              aria-labelledby="opportunity-how"
              className="flex flex-col gap-md"
            >
              <h2 id="opportunity-how" className="heading-h3 text-text-primary">
                {copy.opportunityDetail.howToApplyHeading}
              </h2>
              <RichText value={opportunity.howToApply} />
            </section>
          ) : null}

          <ApplicationSection
            detailPath={detailPath}
            opportunity={opportunity}
            result={result}
            isSubmitting={isSubmitting}
          />
        </div>

        <aside className="flex w-full flex-col gap-lg lg:w-[22rem] lg:shrink-0">
          <DetailList
            heading={copy.opportunityDetail.detailsHeading}
            items={details}
          />

          {opportunity.attachments.length > 0 ? (
            <section
              aria-labelledby="opportunity-documents"
              className="flex flex-col gap-md rounded-card border border-border-subtle bg-surface-raised p-lg"
            >
              <h2
                id="opportunity-documents"
                className="label-md uppercase text-text-tertiary"
              >
                {copy.opportunityDetail.attachmentsHeading}
              </h2>
              <ul className="flex flex-col gap-md">
                {opportunity.attachments.map((file) => (
                  <li key={file.url} className="flex flex-col items-start gap-2xs">
                    {/* Media URLs come from the CMS too; an unusable one keeps
                        the file's name on the page as plain text. */}
                    {safeHref(file.url) ? (
                      <Button
                        as="a"
                        href={safeHref(file.url)}
                        target="_blank"
                        rel="noopener noreferrer"
                        variant="secondary"
                        size="sm"
                      >
                        {file.name}
                      </Button>
                    ) : (
                      <span className="body-sm-bold text-text-primary">
                        {file.name}
                      </span>
                    )}
                    <p className="body-sm text-text-tertiary">
                      {formatAttachmentMeta(file, locale)}
                    </p>
                  </li>
                ))}
              </ul>
            </section>
          ) : null}
        </aside>
      </div>
    </PageShell>
  );
}

/* ---------------------------------------------------------------------------
   APPLICATION SECTION
   Closed, not open yet, handled elsewhere, by email, or the form itself.
   ------------------------------------------------------------------------ */

function ApplicationSection({
  detailPath,
  opportunity,
  result,
  isSubmitting,
}: {
  detailPath: string;
  opportunity: Awaited<ReturnType<typeof loader>>["opportunity"];
  result: ActionResult | undefined;
  isSubmitting: boolean;
}) {
  const { locale, t } = useTranslation();
  const copy = getRouteCopy(locale);

  const errors = result && !result.ok ? result.errors : {};
  const values = result && !result.ok ? result.values : undefined;
  /* This form has no consent checkbox - only the event registration does -
     so the "consent" code cannot occur here; it is narrowed away rather than
     indexed into a table that has no entry for it. */
  const fieldError = (name: string) => {
    const code = errors[name];
    if (!code || code === "consent") return undefined;
    return t(FIELD_ERROR_KEYS[code]);
  };

  if (result?.ok) {
    /* The draft's "[X weeks]" is TBD and the CMS models no response time, so
       the acknowledgement never names one. */
    return (
      <Notice tone="accent" role="status" title={t("form.successTitle")}>
        {copy.opportunityDetail.applicationReceivedBody}
      </Notice>
    );
  }

  if (opportunity.status === "upcoming") {
    return (
      <Notice
        tone="info"
        title={
          opportunity.openDate
            ? interpolate(copy.opportunityDetail.upcomingNote, {
                date: formatOpportunityDate(opportunity.openDate, locale),
              })
            : t("filters.upcoming")
        }
      />
    );
  }

  if (opportunity.status === "closed") {
    return <Notice tone="info" title={copy.opportunityDetail.closedNote} />;
  }

  if (opportunity.externalApplicationUrl) {
    return (
      <Notice tone="info" title={copy.opportunityDetail.externalApplication}>
        {/* `safeHref` gates the CMS URL; without a usable one the notice still
            tells the reader that applications are handled elsewhere. */}
        {safeHref(opportunity.externalApplicationUrl) ? (
          <Button
            as="a"
            href={safeHref(opportunity.externalApplicationUrl)}
            target="_blank"
            rel="noopener noreferrer"
            variant="primary"
            iconEnd={<ArrowIcon />}
          >
            {t("actions.apply")}
          </Button>
        ) : null}
      </Notice>
    );
  }

  return (
    <section
      id="apply"
      aria-labelledby="apply-heading"
      className="flex flex-col gap-lg rounded-card border border-border-subtle bg-surface-raised p-lg"
    >
      <div className="flex flex-col gap-xs">
        <h2 id="apply-heading" className="heading-h3 text-text-primary">
          {copy.opportunityDetail.applyHeading}
        </h2>
        <p className="body-sm text-text-secondary">
          {copy.opportunityDetail.formIntro}
        </p>
      </div>

      {result && !result.ok && result.failed ? (
        <Notice tone="danger" role="alert" title={t("form.errorGeneric")}>
          {copy.form.submissionFailed}
        </Notice>
      ) : null}

      <Form method="post" action={detailPath} className="flex flex-col gap-md">
        <div className="grid gap-md sm:grid-cols-2">
          <Input
            name="fullName"
            label={t("form.name")}
            required
            autoComplete="name"
            defaultValue={values?.fullName}
            error={fieldError("fullName")}
          />
          <Input
            name="email"
            type="email"
            label={t("form.email")}
            required
            autoComplete="email"
            inputMode="email"
            defaultValue={values?.email}
            error={fieldError("email")}
          />
          <Input
            name="organisation"
            label={t("form.organisation")}
            hint={t("form.optional")}
            autoComplete="organization"
            defaultValue={values?.organisation}
            className="sm:col-span-2"
          />
        </div>

        <Textarea
          name="message"
          label={t("form.message")}
          hint={copy.opportunityDetail.messageHint}
          required
          rows={6}
          defaultValue={values?.message}
          error={fieldError("message")}
        />

        {/* Honeypot. Hidden from sight and from assistive technology alike. */}
        <div aria-hidden="true" className="hidden">
          <label htmlFor={HONEYPOT_FIELD}>{copy.form.honeypotLabel}</label>
          <input
            id={HONEYPOT_FIELD}
            name={HONEYPOT_FIELD}
            type="text"
            tabIndex={-1}
            autoComplete="off"
          />
        </div>

        <div className="flex flex-wrap items-center gap-sm">
          <Button
            type="submit"
            variant="primary"
            isLoading={isSubmitting}
            iconEnd={<ArrowIcon />}
          >
            {t("actions.apply")}
          </Button>
        </div>
      </Form>
    </section>
  );
}