"use client";

import { useEffect, useRef } 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 { openSettings } from "@/lib/ui-events";
import { cn } 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>;
  onSubmit: () => 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);

  // 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";

  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("homework.title")}</span>
        </h1>
        <p className="max-w-xl text-[15px] text-frost-600 dark:text-frost-300">{t("homework.subtitle")}</p>
      </section>

      {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}

      {/* ------------------------------------------------ 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) => {
            const selected = mode === option.id;
            return (
              <button
                key={option.id}
                type="button"
                aria-pressed={selected}
                onClick={() => onModeChange(option.id)}
                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>
            );
          })}
        </div>
      </section>

      {/* -------------------------------------------------------- CTA */}
      <div className="space-y-2">
        <Button size="lg" className="touch-target w-full" onClick={onSubmit} disabled={!canSubmit} loading={intake.busy}>
          {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>
  );
}