"use client";

import { AnimatePresence, motion, useDragControls, useReducedMotion } from "framer-motion";
import { useEffect, useRef, useState } from "react";

import { LOCALES, useI18n, type Locale } from "@/lib/i18n";
import { cn } from "@/lib/utils";
import { openInstallSheet, useInstallAvailable } from "@/lib/install";
import { clearApiKey, saveSettings } from "@/lib/settings";
import { useHealth } from "@/lib/use-health";
import {
  AlertTriangleIcon,
  CheckCircleIcon,
  ChevronDownIcon,
  ChevronRightIcon,
  DownloadIcon,
  XCircleIcon,
} from "@/components/icons";
import { Button, Spinner } from "@/components/ui";

/** “Checked just now”, or the clock time once the result is older. */
function freshnessLabel(checkedAt: number, locale: Locale, t: (key: string, vars?: Record<string, string>) => string) {
  if (Date.now() - checkedAt < 90_000) return t("health.checkedNow");
  const time = new Date(checkedAt).toLocaleTimeString(locale === "cs" ? "cs-CZ" : "en-US", {
    hour: "2-digit",
    minute: "2-digit",
  });
  return t("health.checkedAt", { time });
}

export function SettingsDialog({ open, onClose }: { open: boolean; onClose: () => void }) {
  const { health, loading, error, refresh, apiKey, checkedAt } = useHealth();
  const installAvailable = useInstallAvailable();
  const { locale, setLocale, t } = useI18n();
  const [keyDraft, setKeyDraft] = useState(apiKey);
  const [reveal, setReveal] = useState(false);
  const [saved, setSaved] = useState(false);
  const [confirmRemove, setConfirmRemove] = useState(false);
  const [canScroll, setCanScroll] = useState(false);
  const [phone, setPhone] = useState(false);
  const dragControls = useDragControls();
  const reduceMotion = useReducedMotion();
  const scrollRef = useRef<HTMLDivElement>(null);
  const contentRef = useRef<HTMLDivElement>(null);

  // Swipe-to-dismiss is a phone gesture; the desktop dialog is unchanged.
  useEffect(() => {
    const query = window.matchMedia("(max-width: 639px)");
    const sync = () => setPhone(query.matches);
    sync();
    query.addEventListener("change", sync);
    return () => query.removeEventListener("change", sync);
  }, []);

  useEffect(() => {
    if (!open) return;
    setKeyDraft(apiKey);
    setSaved(false);
    setConfirmRemove(false);
    const onKey = (event: KeyboardEvent) => {
      if (event.key === "Escape") onClose();
    };
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, [open, apiKey, onClose]);

  // The scroll cue: a small chevron that fades in whenever more content is
  // below the fold, and out once the bottom is reached.
  const updateCue = () => {
    const element = scrollRef.current;
    if (!element) return;
    setCanScroll(element.scrollHeight - element.scrollTop - element.clientHeight > 24);
  };

  useEffect(() => {
    if (!open) return;
    const element = scrollRef.current;
    const content = contentRef.current;
    if (!element) return;
    updateCue();
    const observer = new ResizeObserver(updateCue);
    if (content) observer.observe(content);
    return () => observer.disconnect();
  }, [open]);

  // Drag only from the handle/header, and only while the body is at the top.
  const startSheetDrag = (event: React.PointerEvent) => {
    if (!phone) return;
    if ((event.target as HTMLElement).closest("button, a, input, summary")) return;
    const element = scrollRef.current;
    if (element && element.scrollTop > 2) return;
    dragControls.start(event);
  };

  const save = () => {
    saveSettings({ apiKey: keyDraft.trim() });
    setSaved(true);
    window.setTimeout(() => setSaved(false), 2500);
  };

  const forget = () => {
    clearApiKey();
    setKeyDraft("");
    setConfirmRemove(false);
  };

  const needsKeyMode = health?.authMode === "user-key";

  return (
    <AnimatePresence>
      {open ? (
        <motion.div
          className="fixed inset-0 z-50 flex items-end justify-center bg-frost-950/35 p-0 backdrop-blur-md sm:items-center sm:p-6"
          initial={{ opacity: 0 }}
          animate={{ opacity: 1 }}
          exit={{ opacity: 0 }}
          onClick={onClose}
        >
          <motion.div
            role="dialog"
            aria-modal="true"
            aria-labelledby="settings-title"
            drag={phone ? "y" : false}
            dragControls={dragControls}
            dragListener={false}
            dragMomentum={false}
            dragConstraints={{ top: 0, bottom: 0 }}
            dragElastic={{ top: 0, bottom: 0.55 }}
            onDragEnd={(_, gesture) => {
              if (gesture.offset.y > 90 || gesture.delta.y > 140 || gesture.velocity.y > 700) onClose();
            }}
            initial={reduceMotion ? { opacity: 0 } : phone ? { y: "100%", opacity: 0 } : { y: 48, opacity: 0 }}
            animate={reduceMotion ? { opacity: 1 } : { y: 0, opacity: 1 }}
            exit={reduceMotion ? { opacity: 0 } : phone ? { y: "100%", opacity: 0 } : { y: 32, opacity: 0 }}
            transition={phone ? { duration: 0.34, ease: [0.22, 1, 0.36, 1] } : { type: "spring", stiffness: 340, damping: 32 }}
            onClick={(event) => event.stopPropagation()}
            className="glass-panel relative flex max-h-[90dvh] w-full max-w-lg flex-col overflow-hidden rounded-t-[1.6rem] shadow-2xl sm:rounded-[1.35rem]"
          >
            {/* handle + header: the drag strip. Fixed, so the body scrolls. */}
            <div
              onPointerDown={startSheetDrag}
              className={cn("shrink-0 px-5 pt-2", phone && "cursor-grab touch-none active:cursor-grabbing")}
            >
              <div aria-hidden className="mx-auto flex h-6 w-full items-center justify-center">
                <span className="h-1 w-9 rounded-full bg-[var(--text-subtle)] opacity-40" />
              </div>
              <div className="mb-3 flex items-start justify-between gap-4">
                <div>
                  <h2 id="settings-title" className="text-lg font-semibold tracking-[-0.02em] text-frost-950 dark:text-frost-50">
                    {t("settings.title")}
                  </h2>
                  <p className="text-sm text-frost-600 dark:text-frost-300">
                    {t("settings.subtitle.before")}{" "}
                    <code className="rounded bg-frost-100 px-1 dark:bg-white/10">.env.local</code>{" "}
                    {t("settings.subtitle.after")}
                  </p>
                </div>
                <Button
                  variant="ghost"
                  size="sm"
                  className="touch-target -mr-1 shrink-0"
                  onClick={onClose}
                  aria-label={t("settings.close")}
                >
                  ✕
                </Button>
              </div>
            </div>

            {/* scrollable body: the safe area comes from pb-safe + a spacer */}
            <div
              ref={scrollRef}
              onScroll={updateCue}
              className="sheet-scroll thin-scroll min-h-0 flex-1 overflow-y-auto px-5 pb-safe"
            >
              <div ref={contentRef}>
                {/* --------------------------------------------- language */}
                <section className="mb-4 space-y-2 rounded-2xl border border-[var(--hairline)] bg-[var(--surface-sunken)] p-3">
                  <h3 className="text-sm font-semibold text-frost-950 dark:text-frost-50">
                    {t("language.label")}
                  </h3>
                  <div className="segmented" role="group" aria-label={t("language.label")}>
                    {LOCALES.map((entry) => (
                      <button
                        key={entry.id}
                        type="button"
                        aria-pressed={locale === entry.id}
                        onClick={() => setLocale(entry.id)}
                      >
                        {entry.label}
                      </button>
                    ))}
                  </div>
                  <p className="text-[11px] leading-relaxed text-[var(--text-subtle)]">
                    {t("language.note")}
                  </p>
                </section>

                {/* ------------------------------------------------ API key */}
                <section className="mb-4 space-y-3 rounded-2xl border border-[var(--hairline)] bg-[var(--surface-sunken)] p-3">
                  <div className="flex flex-wrap items-center justify-between gap-2">
                    <h3 className="text-sm font-semibold text-frost-950 dark:text-frost-50">
                      {t("settings.apiKey")}
                    </h3>
                    {apiKey ? (
                      <span className="rounded-full bg-emerald-100 px-2 py-0.5 text-[11px] font-bold text-emerald-900 dark:bg-emerald-400/20 dark:text-emerald-200">
                        {t("settings.savedInBrowser")}
                      </span>
                    ) : needsKeyMode ? (
                      <span className="rounded-full bg-amber-50 px-2 py-0.5 text-[11px] font-semibold text-amber-800 dark:bg-amber-500/15 dark:text-amber-200">
                        {t("settings.required")}
                      </span>
                    ) : (
                      <span className="rounded-full bg-[var(--surface-sunken)] px-2 py-0.5 text-[11px] font-semibold text-[var(--text-muted)]">
                        {t("settings.notNeeded")}
                      </span>
                    )}
                  </div>

                  {/* Phones: the field gets its own row, the two actions stack
                      underneath at full touch-target size. */}
                  <div className="flex flex-col gap-2 sm:flex-row sm:flex-wrap sm:items-center">
                    <label className="sr-only" htmlFor="ollama-api-key">
                      {t("settings.apiKey")}
                    </label>
                    <input
                      id="ollama-api-key"
                      type={reveal ? "text" : "password"}
                      value={keyDraft}
                      onChange={(event) => setKeyDraft(event.target.value)}
                      onKeyDown={(event) => {
                        event.stopPropagation();
                        if (event.key === "Enter") save();
                      }}
                      placeholder={t("settings.pasteKey")}
                      autoComplete="off"
                      spellCheck={false}
                      className="w-full min-w-0 rounded-xl border border-[var(--hairline)] bg-[var(--surface-strong)] px-3 py-2 font-mono text-xs text-frost-950 outline-none transition placeholder:font-sans placeholder:text-[var(--text-subtle)] focus:border-accent-500 dark:text-frost-50 sm:min-w-40 sm:flex-1"
                    />
                    <div className="flex items-center gap-2 sm:contents">
                      <Button
                        size="sm"
                        variant="secondary"
                        className="touch-target flex-1 sm:flex-none"
                        onClick={() => setReveal((value) => !value)}
                      >
                        {reveal ? t("settings.hide") : t("settings.show")}
                      </Button>
                      <Button
                        size="sm"
                        className="touch-target flex-1 sm:flex-none"
                        onClick={save}
                        disabled={keyDraft.trim() === apiKey}
                      >
                        {t("common.save")}
                      </Button>
                    </div>
                  </div>

                  <div className="space-y-2">
                    <p className="text-[11px] leading-relaxed text-[var(--text-subtle)]">
                      {t("settings.keyNote")}
                    </p>

                    <details className="group">
                      <summary className="touch-target -mt-1 flex cursor-pointer list-none items-center gap-1.5 text-[11px] font-medium text-[var(--text-muted)] transition hover:text-[var(--text)] [&::-webkit-details-marker]:hidden">
                        <ChevronDownIcon className="size-3.5 shrink-0 transition-transform group-open:rotate-180" />
                        {t("settings.localTipTitle")}
                      </summary>
                      <p className="pt-0.5 text-[11px] leading-relaxed text-[var(--text-subtle)]">
                        {t("settings.localTipSet")} <code>OLLAMA_AUTH=local</code>{" "}
                        {t("settings.keyNoteAfter")} <code>.env.local</code> {t("settings.keyNoteEnd")}{" "}
                        <code>ollama signin</code>
                        {t("settings.keyNoteEnd2")}
                      </p>
                    </details>
                  </div>

                  <div className="flex flex-wrap items-center gap-x-3 gap-y-1">
                    <Button
                      size="sm"
                      variant="secondary"
                      className="touch-target"
                      onClick={() => void refresh()}
                      loading={loading}
                    >
                      {t("settings.testConnection")}
                    </Button>
                    {saved ? (
                      <span className="text-xs font-semibold text-emerald-700 dark:text-emerald-300">
                        {t("settings.savedTesting")}
                      </span>
                    ) : null}
                    {apiKey && !confirmRemove ? (
                      <Button
                        size="sm"
                        variant="ghost"
                        className="touch-target -ml-2.5 text-rose-700 hover:bg-rose-500/10 dark:text-rose-300"
                        onClick={() => setConfirmRemove(true)}
                      >
                        {t("settings.removeKey")}
                      </Button>
                    ) : null}
                  </div>

                  {apiKey && confirmRemove ? (
                    <div className="rounded-xl border border-rose-300/70 bg-rose-50 p-3 dark:border-rose-400/25 dark:bg-rose-500/10">
                      <p className="text-[12px] leading-relaxed text-rose-900 dark:text-rose-100">
                        {t("settings.removeKeyConfirm")}
                      </p>
                      <div className="mt-1.5 flex flex-wrap gap-2">
                        <Button size="sm" variant="danger" className="touch-target" onClick={forget}>
                          {t("settings.removeKeyYes")}
                        </Button>
                        <Button
                          size="sm"
                          variant="ghost"
                          className="touch-target"
                          onClick={() => setConfirmRemove(false)}
                        >
                          {t("common.cancel")}
                        </Button>
                      </div>
                    </div>
                  ) : null}
                </section>

                {/* ------------------------------------------------ install */}
                {installAvailable ? (
                  <section className="mb-4 rounded-2xl border border-[var(--hairline)] bg-[var(--surface-sunken)] p-1.5">
                    <button
                      type="button"
                      onClick={() => {
                        onClose();
                        openInstallSheet();
                      }}
                      className="flex w-full items-center gap-3 rounded-xl px-2.5 py-2 text-left transition hover:bg-[var(--hover)]"
                    >
                      <span
                        aria-hidden
                        className="grid size-9 shrink-0 place-items-center rounded-xl border border-[var(--hairline)] bg-[var(--surface)] text-[var(--text-muted)]"
                      >
                        <DownloadIcon className="size-4" />
                      </span>
                      <span className="min-w-0 flex-1">
                        <span className="block text-sm font-semibold text-frost-950 dark:text-frost-50">
                          {t("settings.installApp")}
                        </span>
                        <span className="block text-[12px] text-[var(--text-subtle)]">
                          {t("settings.addToHome")}
                        </span>
                      </span>
                      <ChevronRightIcon className="size-4 shrink-0 text-[var(--text-subtle)]" />
                    </button>
                  </section>
                ) : null}

                {error ? (
                  <div className="rounded-2xl bg-rose-100 p-3 text-sm text-rose-900 dark:bg-rose-500/15 dark:text-rose-200">
                    {error}
                  </div>
                ) : null}

                {loading ? (
                  <div className="flex items-center gap-3 py-2 text-sm text-[var(--text-muted)]">
                    <Spinner className="size-4" /> {t("settings.checking")}
                  </div>
                ) : checkedAt ? (
                  <p className="py-1 text-[11px] font-medium text-[var(--text-subtle)]">
                    {freshnessLabel(checkedAt, locale, t)}
                  </p>
                ) : null}

                {health ? <HealthPanel health={health} /> : null}

                {/* keeps real content out of the 36px fade strip at the bottom */}
                <div className="h-9" aria-hidden />
              </div>
            </div>

            {/* scroll cue: a bare chevron inside the fade strip, so it never
                covers text (the .sheet-scroll mask fades what is underneath) */}
            <div
              aria-hidden
              className={cn(
                "pointer-events-none absolute inset-x-0 bottom-0 flex h-9 items-end justify-center pb-1.5 transition-opacity duration-200",
                canScroll ? "opacity-100" : "opacity-0",
              )}
            >
              <ChevronDownIcon className="size-4 text-[var(--text-subtle)]" />
            </div>
          </motion.div>
        </motion.div>
      ) : null}
    </AnimatePresence>
  );
}

function HealthPanel({ health }: { health: ReturnType<typeof useHealth>["health"] }) {
  const { t } = useI18n();
  if (!health) return null;
  const tone = health.ok ? "emerald" : health.needsKey ? "amber" : health.reachable ? "amber" : "rose";
  const toneClasses: Record<string, string> = {
    emerald: "bg-emerald-50 text-emerald-800 dark:bg-emerald-500/15 dark:text-emerald-200",
    amber: "bg-amber-50 text-amber-800 dark:bg-amber-500/15 dark:text-amber-200",
    rose: "bg-rose-50 text-rose-800 dark:bg-rose-500/15 dark:text-rose-200",
  };

  return (
    <div className="space-y-3">
      <div className={cn("flex items-start gap-2 rounded-2xl p-3 text-sm font-medium", toneClasses[tone])}>
        <span aria-hidden className="mt-0.5 shrink-0">
          {tone === "emerald" ? (
            <CheckCircleIcon className="size-5" />
          ) : tone === "amber" ? (
            <AlertTriangleIcon className="size-5" />
          ) : (
            <XCircleIcon className="size-5" />
          )}
        </span>
        <span>
          {health.ok
            ? t("health.ok")
            : health.needsKey
              ? t("health.needsKey")
              : health.keyAccepted === false
                ? t("health.rejected")
                : health.reachable
                  ? t("health.modelMissing")
                  : t("health.unreachable")}
          {health.error ? <p className="mt-1 font-normal">{health.error}</p> : null}
        </span>
      </div>

      <dl className="grid grid-cols-2 gap-2 text-sm">
        <Info
          label={t("health.auth")}
          value={
            health.authMode === "user-key"
              ? t("health.authUserKey")
              : health.authMode === "server"
                ? t("health.authServer")
                : t("health.authLocal")
          }
        />
        <Info label={t("health.endpoint")} value={health.baseUrl} mono />
        <Info
          label={t("health.mode")}
          value={health.mode === "direct-cloud" ? t("health.modeCloud") : t("health.modeLocal")}
        />
        <Info
          label={t("health.key")}
          value={
            health.needsKey
              ? t("health.keyMissing")
              : health.keyAccepted === true
                ? t("health.keyAccepted")
                : health.keyAccepted === false
                  ? t("health.keyRejected")
                  : health.authMode === "local"
                    ? t("health.keyNotNeeded")
                    : t("health.keyUnknown")
          }
        />
      </dl>

      <div className="space-y-2">
        <ModelRow title={t("health.visionModel")} model={health.vision} />
        <ModelRow title={t("health.textModel")} model={health.text} />
      </div>

      {health.mode === "direct-cloud" && health.needsKey ? (
        <p className="rounded-2xl bg-[var(--surface-sunken)] p-3 text-xs text-[var(--text-muted)]">
          {t("health.createKey.before")}{" "}
          <a className="font-semibold underline underline-offset-2" href="https://ollama.com/settings/keys" target="_blank" rel="noreferrer">
            ollama.com/settings/keys
          </a>{" "}
          {t("health.createKey.after")} <code>ollama signin</code> {t("health.createKey.end")}{" "}
          <code>OLLAMA_AUTH=local</code>.
        </p>
      ) : null}
    </div>
  );
}

function Info({ label, value, mono }: { label: string; value: string; mono?: boolean }) {
  return (
    <div className="rounded-2xl border border-[var(--hairline)] bg-[var(--surface-sunken)] p-3">
      <dt className="text-xs uppercase tracking-wide text-[var(--text-subtle)]">{label}</dt>
      <dd className={cn("mt-0.5 break-words font-semibold", mono && "font-mono text-xs")}>{value}</dd>
    </div>
  );
}

function ModelRow({
  title,
  model,
}: {
  title: string;
  model: { configured: string; resolved: string; available: boolean | null; note?: string };
}) {
  const { t } = useI18n();
  const badge =
    model.available === true
      ? { text: t("health.available"), className: "bg-emerald-100 text-emerald-900 dark:bg-emerald-400/20 dark:text-emerald-200" }
      : model.available === false
        ? { text: t("health.notFound"), className: "bg-rose-50 text-rose-800 dark:bg-rose-500/15 dark:text-rose-200" }
        : { text: t("health.unknown"), className: "bg-[var(--surface-sunken)] text-[var(--text-muted)]" };

  return (
    <div className="rounded-2xl border border-[var(--hairline)] bg-[var(--surface-sunken)] p-3">
      <div className="flex items-center justify-between gap-2">
        <p className="text-xs uppercase tracking-wide text-[var(--text-subtle)]">{title}</p>
        <span className={cn("rounded-full px-2 py-0.5 text-[11px] font-bold", badge.className)}>
          {badge.text}
        </span>
      </div>
      <p className="mt-1 font-mono text-sm font-semibold">{model.resolved}</p>
      {model.configured !== model.resolved ? (
        <p className="text-xs text-[var(--text-subtle)]">
          {t("health.configuredAs", { model: model.configured })}
        </p>
      ) : null}
      {model.note ? <p className="mt-1 text-xs text-amber-700 dark:text-amber-300">{model.note}</p> : null}
    </div>
  );
}