"use client";

import { ChangeEvent, useCallback, useRef, useState } from "react";
import { Camera } from "lucide-react";
import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
import { useAuth, useCurrentUserId } from "@/lib/auth/auth-context";
import { todayLocalIsoDate } from "@/lib/dates";
import { PhotoMetadataError, PhotoTooLargeError, preparePhoto } from "@/lib/photos/reencode";
import {
  PHOTOS_PER_INSPECTION_MAX,
  addDraftPhoto,
  listSessionPhotos,
  removePhoto,
} from "@/lib/photos/store";
import { cn } from "@/lib/utils";
import { Button } from "@/components/ui/button";
import { ConfirmDialog } from "@/components/confirm-dialog";
import { FormSection } from "@/components/form/form-section";

/** Prefix of the queries that read one form's photos from this device. */
export const PHOTO_SESSION_QUERY_KEY = ["photo-session"] as const;

const LIMIT_MESSAGE = `Höchstens ${PHOTOS_PER_INSPECTION_MAX} Fotos je Durchsicht. Entferne eines, um ein neues aufzunehmen.`;

interface Notice {
  text: string;
  isError: boolean;
}

const NO_NOTICE: Notice = { text: "", isError: false };

function captureError(error: unknown): Notice {
  if (error instanceof PhotoTooLargeError) {
    return { text: "Das Foto ist zu groß. Bitte noch einmal aufnehmen.", isError: true };
  }
  if (error instanceof PhotoMetadataError) {
    return {
      text: "Foto wurde nicht gespeichert: Die Standortdaten ließen sich nicht entfernen.",
      isError: true,
    };
  }
  return { text: "Foto konnte nicht gespeichert werden.", isError: true };
}

interface PhotoThumbnailProps {
  blob: Blob;
  alt: string;
  className?: string;
}

/** A photo stored on this device, shown from an object URL. */
export function PhotoThumbnail({ blob, alt, className }: PhotoThumbnailProps) {
  // The URL lives exactly as long as the mounted image (ref cleanup), also
  // through StrictMode's unmount and remount.
  const showBlob = useCallback(
    (image: HTMLImageElement | null) => {
      if (!image) return;
      const url = URL.createObjectURL(blob);
      image.src = url;
      return () => URL.revokeObjectURL(url);
    },
    [blob],
  );
  // eslint-disable-next-line @next/next/no-img-element -- blob: object URL, next/image cannot handle this
  return <img ref={showBlob} alt={alt} className={className} />;
}

interface PhotoCaptureFieldProps {
  /** Position of the section in its form. */
  step?: number;
  /** The form's photo session (`photoSessionId` in its draft values). */
  sessionId: string;
  /** The inspection date (yyyy-mm-dd), part of each file name. */
  date: string;
  /** A photo was taken or removed: the form now has something to keep. */
  onChange?: () => void;
}

/**
 * „Foto aufnehmen" in an inspection form. Each photo is re-encoded without
 * EXIF/GPS and stored on the device at once, so it is kept with the form
 * draft and works without a network. Uploaded after the inspection is saved.
 * Shown only to users who may upload documents.
 */
export function PhotoCaptureField(props: PhotoCaptureFieldProps) {
  const { hasPermission } = useAuth();
  if (!hasPermission("documents:upload")) {
    return null;
  }
  return <PhotoCapture {...props} />;
}

function PhotoCapture({ step, sessionId, date, onChange }: PhotoCaptureFieldProps) {
  const queryClient = useQueryClient();
  const ownerUserId = useCurrentUserId();
  const inputRef = useRef<HTMLInputElement>(null);
  const [notice, setNotice] = useState<Notice>(NO_NOTICE);
  const queryKey = [...PHOTO_SESSION_QUERY_KEY, sessionId];

  const { data: photos = [] } = useQuery({
    queryKey,
    queryFn: () => listSessionPhotos(sessionId),
    // Reads this device's storage, never the network.
    networkMode: "always",
  });
  const isFull = photos.length >= PHOTOS_PER_INSPECTION_MAX;

  async function showStoredPhotos(): Promise<number> {
    await queryClient.invalidateQueries({ queryKey });
    return queryClient.getQueryData<unknown[]>(queryKey)?.length ?? 0;
  }

  const add = useMutation({
    networkMode: "always",
    mutationFn: async (file: File) => {
      // Never store a photo without an owner: it would follow the next user.
      if (!ownerUserId) {
        throw new Error("No signed-in user");
      }
      const blob = await preparePhoto(file);
      return addDraftPhoto({ sessionId, ownerUserId, blob, date: date || todayLocalIsoDate() });
    },
    onSuccess: async () => {
      onChange?.();
      const count = await showStoredPhotos();
      setNotice({ text: `Foto ${count} gespeichert.`, isError: false });
    },
    onError: (error) => setNotice(captureError(error)),
  });

  const remove = useMutation({
    networkMode: "always",
    mutationFn: (id: string) => removePhoto(id),
    onSuccess: async () => {
      onChange?.();
      await showStoredPhotos();
      setNotice({ text: "Foto entfernt.", isError: false });
    },
    onError: () => setNotice({ text: "Foto konnte nicht entfernt werden.", isError: true }),
  });

  function openCamera() {
    if (isFull) {
      setNotice({ text: LIMIT_MESSAGE, isError: true });
      return;
    }
    setNotice(NO_NOTICE);
    inputRef.current?.click();
  }

  function handleFile(event: ChangeEvent<HTMLInputElement>) {
    const file = event.target.files?.[0];
    // Cleared, so the same picture can be chosen again after removing it.
    event.target.value = "";
    if (!file) return;
    if (isFull) {
      setNotice({ text: LIMIT_MESSAGE, isError: true });
      return;
    }
    add.mutate(file);
  }

  return (
    <FormSection
      step={step}
      title="Fotos"
      description={`Bis zu ${PHOTOS_PER_INSPECTION_MAX} Fotos. Standortdaten werden vor dem Speichern entfernt.`}
    >
      {photos.length > 0 ? (
        <ul className="grid grid-cols-3 gap-3" aria-label="Fotos dieser Durchsicht">
          {photos.map((photo, index) => {
            const name = `Foto ${index + 1}`;
            return (
              <li key={photo.id} className="flex flex-col gap-1">
                <PhotoThumbnail
                  blob={photo.blob}
                  alt={name}
                  className="aspect-square w-full rounded-lg border border-border/60 object-cover"
                />
                <ConfirmDialog
                  triggerLabel="Entfernen"
                  triggerAriaLabel={`Entfernen: ${name}`}
                  triggerVariant="ghost"
                  triggerSize="touch"
                  title={`${name} entfernen?`}
                  description="Das Foto wird von diesem Gerät gelöscht."
                  confirmLabel="Entfernen"
                  onConfirm={() => remove.mutate(photo.id)}
                  isPending={remove.isPending}
                />
              </li>
            );
          })}
        </ul>
      ) : null}
      <Button
        type="button"
        variant="outline"
        size="touch"
        className="w-fit"
        disabled={add.isPending}
        onClick={openCamera}
      >
        <Camera aria-hidden />
        {add.isPending ? "Foto wird gespeichert…" : "Foto aufnehmen"}
      </Button>
      <input
        ref={inputRef}
        type="file"
        accept="image/*"
        capture="environment"
        className="hidden"
        tabIndex={-1}
        aria-hidden
        onChange={handleFile}
      />
      <p
        role="status"
        aria-live="polite"
        className={cn(
          "text-sm empty:hidden",
          notice.isError ? "font-medium text-destructive" : "text-muted-foreground",
        )}
      >
        {notice.text}
      </p>
    </FormSection>
  );
}