import { useNavigate, useParams } from "react-router-dom";

import type { DrugRef, Indication, MedsReference } from "../api/types";
import { AppShell, Notice, TopBar } from "../components/AppShell";
import { Icon, type IconName } from "../components/Icon";
import { useMedsReference } from "../content/reference";
import { ru } from "../content/ru";
import { useDialog } from "../dialog/DialogContext";
import { sendSideEffect } from "./Meds";
import { useToday } from "./useToday";

/*
 * E6 · О препарате (spec «Модуль Лекарства»: карточка препарата). Patient information from the drug reference
 * built on the Minzdrav guidelines: when to expect the effect, how long, what may bother, when to see a doctor
 * urgently. No doses or ranges are shown — the prescription comes from the doctor only.
 */

const cap = (s: string) => s.charAt(0).toUpperCase() + s.slice(1);

/** «3–4 недели» → the upper bound in days, for the progress bar (null when the text has no weeks). */
function weeksToDays(text: string | null | undefined): number | null {
  const m = /(\d+)(?:\s*[–-]\s*(\d+))?\s*недел/.exec(text ?? "");
  return m ? Number(m[2] ?? m[1]) * 7 : null;
}

function Section({ icon, tone, title, children }: { icon: IconName; tone?: string; title: string; children: React.ReactNode }) {
  return (
    <section className="drug__sec">
      <h2 className="drug__h">
        <span className={`badge-icon ${tone ? `badge-icon--${tone}` : ""}`}>
          <Icon name={icon} size={18} />
        </span>
        {title}
      </h2>
      {children}
    </section>
  );
}

function EffectTimeline({ day, horizon, when }: { day: number; horizon: number; when: string }) {
  const pct = Math.min(100, (day / horizon) * 100);
  return (
    <div className="timeline" aria-label={ru.meds.card.progress(day)}>
      <div className="timeline__bar">
        <span className="timeline__fill" style={{ width: `${pct}%` }} />
        <span className="timeline__mark" style={{ left: `${pct}%` }} />
      </div>
      <div className="timeline__legend">
        <span>{ru.meds.card.progress(day)}</span>
        <span>{ru.meds.card.effectAt(when)}</span>
      </div>
    </div>
  );
}

function Card({
  drug,
  reference: ref,
  indication,
  day,
  prescribed,
}: {
  drug: DrugRef;
  reference: MedsReference;
  indication: Indication | null;
  day: number | null;
  prescribed?: string;
}) {
  const c = ru.meds.card;
  const ind = indication ? drug.indications[indication] : Object.values(drug.indications)[0];
  const expect = indication === "ptsd" ? ref.texts.expect_effect_ptsd : ref.texts.expect_effect_depression;
  const horizon = weeksToDays(ind?.expected_response);
  const sources = ind?.source ?? "";

  return (
    <div className="drug">
      <header className="drug__head">
        <span className="tile-icon tile-icon--teal tile-icon--xl">
          <Icon name="pill" size={32} />
        </span>
        <div>
          <h1 className="h1">{drug.name_ru}</h1>
          <p className="muted">
            {drug.group}
            {drug.group !== drug.class && `, ${drug.class}`}
          </p>
          {prescribed && (
            <p className="drug__rx">
              <Icon name="doctor" size={18} />
              {c.prescribed}: {prescribed}
            </p>
          )}
        </div>
      </header>

      <div className="drug__grid">
        <div className="drug__col">
          {ind?.expected_response && (
            <Section icon="clock" tone="blue" title={c.effect}>
              {day !== null && horizon && <EffectTimeline day={day} horizon={horizon} when={ind.expected_response} />}
              <p>{expect}</p>
            </Section>
          )}

          {(ind?.course || drug.max_course_days) && (
            <Section icon="calendar" tone="blue" title={c.course}>
              {ind?.course && <p>{ind.course}.</p>}
              {drug.max_course_days && <p>{c.courseShort(drug.max_course_days)}.</p>}
              {indication === "depression" && <p className="muted">{ref.texts.why_continue_depression}</p>}
            </Section>
          )}

          <Section icon="smile" tone="teal" title={c.sideEffects}>
            {drug.diary_items.length ? (
              <ul className="bullets">
                {drug.diary_items.map((s) => (
                  <li key={s}>{s}</li>
                ))}
              </ul>
            ) : (
              <p>{c.sideEffectsNone}</p>
            )}
            <p className="muted">{c.sideEffectsHint}</p>
          </Section>
        </div>

        <div className="drug__col">
          {drug.red_flags.length > 0 && (
            <section className="drug__sec drug__sec--red">
              <h2 className="drug__h">
                <span className="badge-icon badge-icon--red">
                  <Icon name="alert" size={18} />
                </span>
                {c.redFlags}
              </h2>
              <ul className="bullets">
                {drug.red_flags.map((s) => (
                  <li key={s}>{s}</li>
                ))}
              </ul>
              <p>{ref.texts.red_flag}</p>
            </section>
          )}

          <Section icon="shield" tone="blue" title={c.important}>
            <p>{ref.texts.dont_stop_alone}</p>
            {drug.withdrawal_risk === "high" && <p>{c.withdrawal}</p>}
            {drug.overdose_danger && <p>{c.overdose}</p>}
            {ind?.off_label && <p className="muted">{c.offLabel}</p>}
            {drug.monitoring.length > 0 && (
              <>
                <p className="drug__sub">{c.monitoring}:</p>
                <ul className="bullets">
                  {drug.monitoring.map((s) => (
                    <li key={s}>{s}</li>
                  ))}
                </ul>
              </>
            )}
          </Section>

          <Section icon="doc" tone="blue" title={c.instruction}>
            <p>{ref.texts.instruction_fallback}</p>
          </Section>
        </div>
      </div>

      <p className="muted small">{c.source(sources)}</p>
    </div>
  );
}

export function DrugInfo() {
  const c = ru.meds.card;
  const { ref: refId } = useParams();
  const navigate = useNavigate();
  const dialog = useDialog();
  const { plan } = useToday();
  const ref = useMedsReference();
  const drug = ref?.drugs.find((d) => d.id === refId);
  const rx = plan?.prescriptions.find((p) => p.ref_id === refId);

  const ask = () =>
    void dialog.send({ type: "button", button: "menu:med_question" }, c.ask).then((ok) => ok && navigate("/flow"));

  return (
    <AppShell>
      <div className="stack">
        <TopBar onBack={() => navigate("/meds")} />
        {!ref ? (
          <div className="loader" aria-label="Загрузка" />
        ) : !drug ? (
          <Notice>{c.unknown}</Notice>
        ) : (
          <Card
            drug={drug}
            reference={ref}
            indication={rx?.indication ?? null}
            day={rx?.therapy_day ?? null}
            prescribed={rx ? `${cap(rx.drug)}, ${rx.dose} · ${rx.times.join(", ")}` : undefined}
          />
        )}
        {rx && (
          <div className="btn-row btn-row--stack-phone">
            <button
              type="button"
              className="btn btn--outline-red"
              disabled={dialog.busy}
              onClick={() => sendSideEffect(dialog, navigate, plan, rx.drug, ru.meds.reportSideEffect)}
            >
              <Icon name="alert" />
              {ru.meds.reportSideEffect}
            </button>
            {plan?.has_doctor && (
              <button type="button" className="btn btn--outline" disabled={dialog.busy} onClick={ask}>
                <Icon name="question" />
                {c.ask}
              </button>
            )}
          </div>
        )}
      </div>
    </AppShell>
  );
}