"use client";

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

import { CameraIcon, FolderIcon, PlayIcon, PlusIcon, SparklesIcon } from "@/components/icons";
import { Button } from "@/components/ui";
import {
  DOCUMENT_ACCEPT_ATTR,
  documentsToText,
  type ExtractedDocument,
} from "@/lib/documents";
import type { HomeworkMode, HomeworkRecord } from "@/lib/schemas";
import { ACCEPTED_TYPES, formatBytes, imageFilesFromDataTransfer } from "@/lib/image";
import { useI18n } from "@/lib/i18n";
import type { useNotesIntake } from "@/lib/use-notes-intake";
import { useIsPhone } from "@/lib/use-phone";
import { openSettings } from "@/lib/ui-events";
import { cn, truncate } from "@/lib/utils";

import { HomeworkHistory } from "./HomeworkHistory";

/** Same wording the create screen uses for an extracted document. */
function describeExtraction(
  document: ExtractedDocument,
  tr: (key: string, vars?: Record<string, string | number>) => string,
  pl: (n: number, base: string, vars?: Record<string, string | number>) => string,
): string {
  const parts = [
    pl(document.words, "upload.words", { n: document.words.toLocaleString() }),
    document.pages ? pl(document.pages, "upload.pages") : "",
    document.images.length ? pl(document.images.length, "upload.pageImages") : "",
    document.truncated ? tr("upload.truncated") : "",
  ];
  return parts.filter(Boolean).join(" · ");
}

const MODES: Array<{ id: HomeworkMode; icon: React.ReactNode; titleKey: string; subtitleKey: string }> = [
  { id: "make", icon: <SparklesIcon className="size-5" />, titleKey: "homework.mode.make.title", subtitleKey: "homework.mode.make.subtitle" },
  { id: "guide", icon: <PlayIcon className="size-5" />, titleKey: "homework.mode.guide.title", subtitleKey: "homework.mode.guide.subtitle" },
];

export function HomeworkInput({
  mode,
  onModeChange,
  text,
  onTextChange,
  intake,
  onSubmit,
  error,
  history,
  onOpen,
  onDelete,
}: {
  mode: HomeworkMode;
  onModeChange: (mode: HomeworkMode) => void;
  text: string;
  onTextChange: (text: string) => void;
  intake: ReturnType<typeof useNotesIntake>;
  /** `modeOverride` lets the phone mode cards start the run they tapped. */
  onSubmit: (modeOverride?: HomeworkMode) => void;
  error: { message: string; kind?: string } | null;
  history: HomeworkRecord[];
  onOpen: (record: HomeworkRecord) => void;
  onDelete: (id: string) => void;
}) {
  const { t, plural } = useI18n();
  const fileInputRef = useRef<HTMLInputElement>(null);
  const cameraInputRef = useRef<HTMLInputElement>(null);
  const [step, setStep] = useState(1);
  const [pasteOpen, setPasteOpen] = useState(false);
  const isPhone = useIsPhone();
  const reduceMotion = useReducedMotion();

  // Clipboard: screenshots become photos, long copied text becomes the assignment.
  useEffect(() => {
    const onPaste = (event: ClipboardEvent) => {
      const target = event.target as HTMLElement | null;
      const isTextField = target && /^(INPUT|TEXTAREA)$/.test(target.tagName);
      const files = imageFilesFromDataTransfer(event.clipboardData);
      if (files.length > 0) {
        event.preventDefault();
        void intake.addFiles(files);
        return;
      }
      if (!isTextField) {
        const pasted = event.clipboardData?.getData("text/plain")?.trim();
        if (pasted && pasted.length > 40) {
          event.preventDefault();
          onTextChange(text ? `${text}\n${pasted}` : pasted);
        }
      }
    };
    window.addEventListener("paste", onPaste);
    return () => window.removeEventListener("paste", onPaste);
  }, [intake, onTextChange, text]);

  const readyDocuments = intake.documents.filter((entry) => entry.status === "ready" && entry.extracted);
  const documentsBusy = intake.documents.some((entry) => entry.status === "extracting");
  const documentImages = readyDocuments.flatMap((entry) => entry.extracted!.images);
  const documentText = documentsToText(readyDocuments.map((entry) => entry.extracted!));
  const totalBytes = intake.images.reduce((sum, image) => sum + image.bytes, 0);

  const hasContent =
    intake.images.length > 0 || documentImages.length > 0 || text.trim().length > 0 || documentText.trim().length > 0;
  const canSubmit = hasContent && !intake.busy && !documentsBusy;
  const keyError = error?.kind === "needs_key" || error?.kind === "auth";

  const errorCard = error ? (
    <div
      role="alert"
      className="animate-rise rounded-3xl border-2 border-rose-300 bg-rose-50/95 p-4 text-sm text-rose-900 dark:border-rose-400/40 dark:bg-rose-400/10 dark:text-rose-100"
    >
      <p className="font-bold">{keyError ? t("upload.errAuth") : t("homework.error.title")}</p>
      <p className="mt-1">{error.message || t("homework.error.body")}</p>
      <div className="mt-3 flex flex-wrap gap-2">
        {keyError ? (
          <Button size="sm" onClick={openSettings}>
            {t("upload.openSettings")}
          </Button>
        ) : null}
        <Button size="sm" variant={keyError ? "secondary" : "primary"} onClick={() => onSubmit()}>
          {t("common.retry")}
        </Button>
      </div>
    </div>
  ) : null;

  /* Shared mode card: desktop toggles the selection, the phone flow starts it. */
  const modeCard = (option: (typeof MODES)[number], onPick: () => void) => {
    const selected = mode === option.id;
    return (
      <button
        key={option.id}
        type="button"
        aria-pressed={selected}
        onClick={onPick}
        className={cn(
          "flex min-h-24 items-start gap-3 rounded-2xl border p-4 text-left transition",
          selected
            ? "border-accent-400 bg-accent-50/70 ring-2 ring-accent-400/40 dark:bg-accent-500/15"
            : "border-[var(--hairline)] bg-[var(--surface-strong)] hover:bg-[var(--hover)]",
        )}
      >
        <span
          aria-hidden
          className={cn(
            "grid size-10 shrink-0 place-items-center rounded-xl",
            selected ? "grad-ice text-[#06111f]" : "bg-[var(--surface-sunken)] text-[var(--text-muted)]",
          )}
        >
          {option.icon}
        </span>
        <span className="min-w-0">
          <span className="block text-[15px] font-semibold leading-snug text-[var(--text)]">
            {t(option.titleKey)}
          </span>
          <span className="mt-0.5 block text-[12.5px] leading-relaxed text-[var(--text-subtle)]">
            {t(option.subtitleKey)}
          </span>
        </span>
      </button>
    );
  };

  const fileInput = (
    <input
      ref={fileInputRef}
      type="file"
      accept={`${ACCEPTED_TYPES.join(",")},${DOCUMENT_ACCEPT_ATTR}`}
      multiple
      className="sr-only"
      onChange={(event) => {
        void intake.addFiles(Array.from(event.target.files ?? []));
        event.target.value = "";
      }}
    />
  );
  const cameraInput = (
    <input
      ref={cameraInputRef}
      type="file"
      accept="image/*"
      capture="environment"
      className="sr-only"
      onChange={(event) => {
        void intake.addFiles(Array.from(event.target.files ?? []));
        event.target.value = "";
      }}
    />
  );

  /* Phones: the 2-step flow. Same intake and mode state as the desktop page. */
  if (isPhone) {
    const stepLabel = step === 1 ? t("homework.phone.assignment") : t("homework.phone.mode");
    const fileSummary = [
      intake.images.length > 0 ? plural(intake.images.length, "upload.photoCount") : "",
      intake.documents.length > 0 ? plural(intake.documents.length, "upload.docSummary") : "",
    ]
      .filter(Boolean)
      .join(" · ");
    const preview = text.trim()
      ? truncate(text.replace(/\s+/g, " ").trim(), 140)
      : fileSummary || t("homework.source.need");
    const showPaste = pasteOpen || text.trim().length > 0;

    return (
      <div className="relative pb-24">
        <section className="space-y-1.5">
          <h1 className="text-[24px] font-semibold leading-tight tracking-[-0.02em] text-[var(--text)]">
            {t("homeworkHeroTitle")}
          </h1>
          <p className="text-[14px] text-frost-600 dark:text-frost-300">{t("homework.subtitle")}</p>
        </section>

        {errorCard}

        <div className="mt-5 space-y-2">
          <div className="flex items-center justify-between gap-3 text-[12px] font-semibold text-[var(--text-subtle)]">
            <h2 className="min-w-0 truncate">{stepLabel}</h2>
            <span className="shrink-0 tabular-nums">{t("common.stepOf", { n: step, total: 2 })}</span>
          </div>
          <div
            role="progressbar"
            aria-label={stepLabel}
            aria-valuemin={1}
            aria-valuemax={2}
            aria-valuenow={step}
            className="h-1 overflow-hidden rounded-full bg-[var(--surface-sunken)]"
          >
            <div
              className="grad-ice h-full rounded-full transition-[width] duration-300 motion-reduce:transition-none"
              style={{ width: `${(step / 2) * 100}%` }}
            />
          </div>
        </div>

        <motion.div
          key={step}
          initial={reduceMotion ? false : { opacity: 0, x: 18 }}
          animate={{ opacity: 1, x: 0 }}
          transition={{ duration: 0.24, ease: [0.22, 1, 0.36, 1] }}
          className="mt-5"
        >
          {step === 1 ? (
            <div className="space-y-3">
              <div className="grid grid-cols-2 gap-2">
                <Button
                  variant="secondary"
                  size="lg"
                  className="touch-target"
                  onClick={() => fileInputRef.current?.click()}
                >
                  <FolderIcon className="size-4" /> {t("homework.source.add")}
                </Button>
                <Button
                  variant="secondary"
                  size="lg"
                  className="touch-target"
                  onClick={() => cameraInputRef.current?.click()}
                >
                  <CameraIcon className="size-4" /> {t("upload.camera")}
                </Button>
              </div>

              <button
                type="button"
                onClick={() => setPasteOpen((value) => !value)}
                aria-expanded={showPaste}
                className="text-[13px] font-semibold text-accent-700 dark:text-accent-200"
              >
                {t("upload.pasteInstead")}
              </button>
              {showPaste ? (
                <textarea
                  id="homework-assignment-phone"
                  value={text}
                  onChange={(event) => onTextChange(event.target.value)}
                  onKeyDown={(event) => event.stopPropagation()}
                  rows={6}
                  placeholder={t("homework.source.placeholder")}
                  aria-label={t("homework.source.textLabel")}
                  className="w-full resize-y rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
                />
              ) : null}

              {intake.images.length > 0 ? (
                <ul className="flex flex-wrap items-center gap-2">
                  {intake.images.map((image) => (
                    <li key={image.id} className="relative">
                      {/* eslint-disable-next-line @next/next/no-img-element -- local thumbnail, no optimisation needed */}
                      <img
                        src={image.dataUrl}
                        alt=""
                        className="size-14 rounded-xl border border-[var(--hairline)] object-cover"
                      />
                      <button
                        type="button"
                        onClick={() => intake.removeImage(image.id)}
                        aria-label={t("upload.remove", { name: image.name })}
                        className="absolute -right-1.5 -top-1.5 grid size-6 place-items-center rounded-full bg-frost-950/80 text-[11px] font-bold text-white"
                      >
                        ✕
                      </button>
                    </li>
                  ))}
                </ul>
              ) : null}

              {intake.documents.length > 0 ? (
                <ul className="flex flex-wrap items-center gap-2">
                  {intake.documents.map((entry) => (
                    <li
                      key={entry.id}
                      className="inline-flex max-w-full items-center gap-1.5 rounded-full border border-[var(--hairline)] bg-[var(--surface-strong)] py-1 pl-2 pr-1"
                    >
                      <span className="rounded-md bg-[var(--surface-sunken)] px-1.5 py-0.5 text-[10px] font-bold uppercase text-[var(--text-muted)]">
                        {entry.name.split(".").pop()?.slice(0, 4) ?? "doc"}
                      </span>
                      <span className="max-w-32 truncate text-[12.5px] font-medium text-[var(--text)]" title={entry.name}>
                        {entry.name}
                      </span>
                      {entry.status === "extracting" ? (
                        <span className="text-[11px] text-[var(--text-subtle)]" title={entry.progress ?? t("upload.reading")}>
                          …
                        </span>
                      ) : null}
                      {entry.status === "error" ? (
                        <span className="text-[11px] font-bold text-rose-600 dark:text-rose-300" title={entry.error}>
                          !
                        </span>
                      ) : null}
                      <button
                        type="button"
                        onClick={() => intake.removeDocument(entry.id)}
                        aria-label={t("upload.remove", { name: entry.name })}
                        className="grid size-6 place-items-center rounded-full text-[11px] font-bold text-[var(--text-subtle)] transition hover:bg-[var(--hover)] hover:text-[var(--text)]"
                      >
                        ✕
                      </button>
                    </li>
                  ))}
                </ul>
              ) : null}

              {intake.documents
                .filter((entry) => entry.status === "error")
                .map((entry) => (
                  <p key={entry.id} className="text-[12px] font-medium text-rose-600 dark:text-rose-300">
                    {entry.name}: {entry.error}
                  </p>
                ))}

              {intake.busy ? (
                <p className="text-[12.5px] font-medium text-[var(--text-muted)]">{t("upload.compressing")}</p>
              ) : null}
              {intake.fileError ? (
                <p role="alert" className="text-xs font-semibold text-rose-600 dark:text-rose-300">
                  {intake.fileError}
                </p>
              ) : null}

              {fileInput}
              {cameraInput}
            </div>
          ) : null}

          {step === 2 ? (
            <div className="space-y-3">
              <div className="rounded-2xl border border-[var(--hairline)] bg-[var(--surface-sunken)] p-3">
                <p className="text-[11px] font-semibold uppercase tracking-wide text-[var(--text-subtle)]">
                  {t("homework.phone.preview")}
                </p>
                <p className="mt-1 text-[13px] leading-relaxed text-[var(--text)]">{preview}</p>
              </div>
              <div className="grid gap-3">
                {MODES.map((option) =>
                  modeCard(option, () => {
                    if (!canSubmit) return;
                    onModeChange(option.id);
                    onSubmit(option.id);
                  }),
                )}
              </div>
              <p className="text-center text-[12px] text-[var(--text-subtle)]">{t("homework.phone.startHint")}</p>
            </div>
          ) : null}
        </motion.div>

        <HomeworkHistory records={history} onOpen={onOpen} onDelete={onDelete} />

        {/* Fixed step bar, floating just above the tab bar. */}
        <div className="fixed inset-x-0 bottom-[calc(env(safe-area-inset-bottom,0px)+4.6rem)] z-20 px-4">
          <div className="glass-panel mx-auto flex max-w-3xl items-center gap-2 p-2">
            <Button
              variant="secondary"
              size="lg"
              className="touch-target flex-1"
              onClick={() => setStep(1)}
              disabled={step === 1}
            >
              {t("common.back")}
            </Button>
            {step === 1 ? (
              <Button size="lg" className="touch-target flex-[1.5]" onClick={() => setStep(2)} disabled={!canSubmit}>
                {t("common.next")}
              </Button>
            ) : null}
          </div>
        </div>
      </div>
    );
  }

  return (
    <div className="relative space-y-6">
      <section className="space-y-2">
        <h1 className="flex flex-wrap items-center gap-x-3 gap-y-1 text-[28px] font-semibold leading-tight tracking-[-0.02em] text-[var(--text)] text-balance sm:text-[32px]">
          <SparklesIcon className="size-8 shrink-0 text-frost-500 dark:text-frost-200" />
          <span>{t("homeworkHeroTitle")}</span>
        </h1>
        <p className="max-w-xl text-[15px] text-frost-600 dark:text-frost-300">{t("homework.subtitle")}</p>
      </section>

      {errorCard}

      {/* ------------------------------------------------ the assignment */}
      <section className="card p-4 sm:p-5">
        <div className="flex flex-wrap items-center justify-between gap-3">
          <div>
            <h2 className="text-[15px] font-semibold tracking-[-0.01em] text-[var(--text)]">
              {t("homework.source.title")}
            </h2>
            <p className="text-[12.5px] text-[var(--text-subtle)]">{t("homework.source.help")}</p>
          </div>
          <div className="flex flex-wrap gap-2">
            <Button variant="secondary" size="sm" className="touch-target" onClick={() => fileInputRef.current?.click()}>
              <FolderIcon className="size-4" /> {t("homework.source.add")}
            </Button>
            <Button variant="secondary" size="sm" className="touch-target" onClick={() => cameraInputRef.current?.click()}>
              <CameraIcon className="size-4" /> {t("upload.camera")}
            </Button>
          </div>
        </div>

        <input
          ref={fileInputRef}
          type="file"
          accept={`${ACCEPTED_TYPES.join(",")},${DOCUMENT_ACCEPT_ATTR}`}
          multiple
          className="sr-only"
          onChange={(event) => {
            void intake.addFiles(Array.from(event.target.files ?? []));
            event.target.value = "";
          }}
        />
        <input
          ref={cameraInputRef}
          type="file"
          accept="image/*"
          capture="environment"
          className="sr-only"
          onChange={(event) => {
            void intake.addFiles(Array.from(event.target.files ?? []));
            event.target.value = "";
          }}
        />

        {intake.images.length === 0 && intake.documents.length === 0 ? (
          <button
            type="button"
            onClick={() => fileInputRef.current?.click()}
            className="mt-4 flex w-full flex-col items-center gap-2 rounded-2xl border-2 border-dashed border-white/70 bg-white/40 px-4 py-10 text-center backdrop-blur-xl transition hover:border-accent-300 hover:bg-white/65 dark:border-white/15 dark:bg-white/[0.05] dark:hover:bg-white/[0.09]"
          >
            <span aria-hidden className="text-frost-500 dark:text-frost-200">
              <PlusIcon className="size-10" />
            </span>
            <span className="text-[14px] font-medium text-[var(--text)]">{t("homework.source.drop")}</span>
            <span className="text-[12px] text-[var(--text-subtle)]">{t("homework.source.formats")}</span>
          </button>
        ) : (
          <div className="mt-4 space-y-2">
            {intake.images.length > 0 ? (
              <div className="flex flex-wrap gap-2">
                {intake.images.map((image) => (
                  <span key={image.id} className="relative">
                    {/* eslint-disable-next-line @next/next/no-img-element -- local thumbnail, no optimisation needed */}
                    <img
                      src={image.dataUrl}
                      alt=""
                      className="size-14 rounded-xl border border-[var(--hairline)] object-cover"
                    />
                    <button
                      type="button"
                      onClick={() => intake.removeImage(image.id)}
                      aria-label={t("upload.remove", { name: image.name })}
                      className="absolute -right-1.5 -top-1.5 grid size-6 place-items-center rounded-full bg-frost-950/80 text-[11px] font-bold text-white"
                    >
                      ✕
                    </button>
                  </span>
                ))}
              </div>
            ) : null}

            {intake.documents.length > 0 ? (
              <ul className="space-y-2">
                {intake.documents.map((entry) => (
                  <li
                    key={entry.id}
                    className="flex items-center gap-3 rounded-xl border border-[var(--hairline)] bg-[var(--surface-strong)] p-2.5"
                  >
                    <span className="rounded-md bg-[var(--surface-sunken)] px-1.5 py-0.5 text-[10px] font-bold uppercase text-[var(--text-muted)]">
                      {entry.name.split(".").pop()?.slice(0, 4) ?? "doc"}
                    </span>
                    <span className="min-w-0 flex-1">
                      <span className="block truncate text-[13px] font-medium text-[var(--text)]">{entry.name}</span>
                      <span className="block text-[11.5px] text-[var(--text-subtle)]">
                        {entry.status === "extracting"
                          ? (entry.progress ?? t("upload.reading"))
                          : entry.status === "error"
                            ? entry.error
                            : entry.extracted
                              ? describeExtraction(entry.extracted, t, plural)
                              : ""}
                      </span>
                    </span>
                    <button
                      type="button"
                      onClick={() => intake.removeDocument(entry.id)}
                      aria-label={t("upload.remove", { name: entry.name })}
                      className="touch-target grid size-8 shrink-0 place-items-center rounded-lg text-[var(--text-subtle)] transition hover:bg-[var(--hover)] hover:text-[var(--text)]"
                    >
                      ✕
                    </button>
                  </li>
                ))}
              </ul>
            ) : null}
          </div>
        )}

        <label
          htmlFor="homework-assignment"
          className="mt-4 block text-[11px] font-semibold uppercase tracking-wider text-[var(--text-subtle)]"
        >
          {t("homework.source.textLabel")}
        </label>
        <textarea
          id="homework-assignment"
          value={text}
          onChange={(event) => onTextChange(event.target.value)}
          onKeyDown={(event) => event.stopPropagation()}
          placeholder={t("homework.source.placeholder")}
          rows={4}
          className="mt-1.5 w-full resize-y rounded-xl border border-[var(--hairline)] bg-[var(--surface-strong)] px-3 py-2.5 text-sm leading-relaxed text-[var(--text)] outline-none transition placeholder:text-[var(--text-subtle)] focus:border-accent-500"
        />

        {intake.images.length > 0 || documentImages.length > 0 ? (
          <p className="mt-2 text-[12px] text-[var(--text-subtle)]">
            {intake.images.length > 0
              ? plural(intake.images.length, "upload.photoSummary", { size: formatBytes(totalBytes) })
              : ""}
            {intake.images.length > 0 && documentImages.length > 0 ? " · " : ""}
            {documentImages.length > 0 ? plural(documentImages.length, "upload.docImages") : ""}
          </p>
        ) : null}

        {intake.busy ? (
          <p className="mt-2 text-[12.5px] font-medium text-[var(--text-muted)]">{t("upload.compressing")}</p>
        ) : null}
        {intake.fileError ? (
          <p role="alert" className="mt-2 text-[12.5px] font-medium text-rose-700 dark:text-rose-300">
            {intake.fileError}
          </p>
        ) : null}
      </section>

      {/* ------------------------------------------------------- mode */}
      <section className="space-y-3">
        <h2 className="text-[15px] font-semibold tracking-[-0.01em] text-[var(--text)]">{t("homework.mode.title")}</h2>
        <div className="grid gap-3 sm:grid-cols-2">
          {MODES.map((option) => modeCard(option, () => onModeChange(option.id)))}
        </div>
      </section>

      {/* -------------------------------------------------------- CTA */}
      <div className="space-y-2">
        <Button size="lg" className="touch-target w-full" onClick={() => onSubmit()} disabled={!canSubmit} loading={intake.busy}>
          <SparklesIcon className="size-5" />
          {mode === "make" ? t("homework.start.make") : t("homework.start.guide")}
        </Button>
        <p className="text-center text-[12px] text-[var(--text-subtle)]">
          {canSubmit ? t("homework.source.ready") : t("homework.source.need")}
        </p>
      </div>

      <HomeworkHistory records={history} onOpen={onOpen} onDelete={onDelete} />
    </div>
  );
}