"use client";

import { useCallback, useRef, useState, type ReactNode } from "react";

const IMAGE_EXTS = new Set([".jpg", ".jpeg", ".png", ".webp", ".gif"]);
const AUDIO_EXTS = new Set([".mp3", ".wav", ".flac", ".m4a", ".aac", ".ogg"]);

export function splitMediaFiles(files: FileList | File[]): {
  images: File[];
  audios: File[];
  ignored: string[];
} {
  const images: File[] = [];
  const audios: File[] = [];
  const ignored: string[] = [];

  for (const file of Array.from(files)) {
    const name = file.name.toLowerCase();
    const dot = name.lastIndexOf(".");
    const ext = dot >= 0 ? name.slice(dot) : "";
    const mime = file.type.toLowerCase();

    if (IMAGE_EXTS.has(ext) || mime.startsWith("image/")) {
      images.push(file);
    } else if (AUDIO_EXTS.has(ext) || mime.startsWith("audio/")) {
      audios.push(file);
    } else {
      ignored.push(file.name);
    }
  }

  return { images, audios, ignored };
}

type Props = {
  disabled?: boolean;
  acceptAudio: string;
  onFiles: (payload: { images: File[]; audios: File[] }) => void;
};

const IMAGE_ACCEPT = "image/jpeg,image/png,image/webp,image/gif,.jpg,.jpeg,.png,.webp,.gif";

function FileHitArea({
  disabled,
  accept,
  multiple,
  onFiles,
  children,
  className,
}: {
  disabled?: boolean;
  accept: string;
  multiple?: boolean;
  onFiles: (list: FileList | null) => void;
  children: ReactNode;
  className?: string;
}) {
  const inputRef = useRef<HTMLInputElement>(null);

  return (
    <div className={`relative ${className ?? ""}`}>
      <input
        ref={inputRef}
        type="file"
        multiple={multiple}
        accept={accept}
        disabled={disabled}
        /* Direct tap on the native input — required on iOS; hidden/sr-only + label often no-ops. */
        className="absolute inset-0 z-10 h-full w-full cursor-pointer opacity-0 disabled:cursor-not-allowed"
        style={{ fontSize: 16 }}
        onChange={(e) => {
          onFiles(e.target.files);
          e.target.value = "";
        }}
      />
      <div className="pointer-events-none">{children}</div>
    </div>
  );
}

/**
 * Mobile: two full-size native file inputs (cover vs audio). Mixed accept + hidden
 * inputs commonly fail to open the picker in iOS Safari / in-app browsers.
 * Desktop: one drop zone with overlay input + drag-and-drop.
 */
export function MediaDropzone({ disabled, acceptAudio, onFiles }: Props) {
  const [dragging, setDragging] = useState(false);

  const handleFiles = useCallback(
    (list: FileList | File[] | null) => {
      if (!list || disabled) return;
      const { images, audios, ignored } = splitMediaFiles(list);
      if (images.length || audios.length) {
        onFiles({ images, audios });
        return;
      }
      if (ignored.length) {
        onFiles({ images: [], audios: [] });
      }
    },
    [disabled, onFiles],
  );

  const dropClass = disabled
    ? "cursor-not-allowed border-gray-800 bg-surface-light/20 opacity-60"
    : dragging
      ? "border-accent bg-accent/10"
      : "border-gray-600 bg-surface-light/30 hover:border-accent/60 hover:bg-accent/[0.06]";

  return (
    <div className="space-y-3">
      <div className="grid gap-3 sm:hidden">
        <FileHitArea
          disabled={disabled}
          accept={IMAGE_ACCEPT}
          onFiles={(list) => handleFiles(list)}
        >
          <div className={`rounded-xl border-2 border-dashed px-5 py-8 text-center ${dropClass}`}>
            <p className="text-base font-medium text-gray-200">Tap to add cover image</p>
            <p className="mt-1 text-xs text-gray-500">JPG, PNG, WebP, or GIF</p>
          </div>
        </FileHitArea>
        <FileHitArea
          disabled={disabled}
          accept={acceptAudio}
          multiple
          onFiles={(list) => handleFiles(list)}
        >
          <div className={`rounded-xl border-2 border-dashed px-5 py-8 text-center ${dropClass}`}>
            <p className="text-base font-medium text-gray-200">Tap to add audio</p>
            <p className="mt-1 text-xs text-gray-500">
              Free: MP3. Pro: WAV / FLAC / AAC / OGG
            </p>
          </div>
        </FileHitArea>
      </div>

      <div className="hidden sm:block">
        <div
          onDragEnter={(e) => {
            e.preventDefault();
            e.stopPropagation();
            if (!disabled) setDragging(true);
          }}
          onDragOver={(e) => {
            e.preventDefault();
            e.stopPropagation();
            if (!disabled) setDragging(true);
          }}
          onDragLeave={(e) => {
            e.preventDefault();
            e.stopPropagation();
            setDragging(false);
          }}
          onDrop={(e) => {
            e.preventDefault();
            e.stopPropagation();
            setDragging(false);
            handleFiles(e.dataTransfer.files);
          }}
        >
          <FileHitArea
            disabled={disabled}
            accept={`${IMAGE_ACCEPT},${acceptAudio}`}
            multiple
            onFiles={(list) => handleFiles(list)}
          >
            <div className={`rounded-xl border-2 border-dashed px-6 py-10 text-center ${dropClass}`}>
              <div className="mx-auto mb-4 flex h-14 w-14 items-center justify-center rounded-full border border-gray-700 bg-surface text-accent">
                <svg
                  viewBox="0 0 24 24"
                  className="h-7 w-7"
                  fill="none"
                  stroke="currentColor"
                  strokeWidth="1.5"
                  aria-hidden
                >
                  <path
                    d="M12 16V4m0 0 4 4m-4-4-4 4"
                    strokeLinecap="round"
                    strokeLinejoin="round"
                  />
                  <path
                    d="M4 14v2.5A3.5 3.5 0 0 0 7.5 20h9a3.5 3.5 0 0 0 3.5-3.5V14"
                    strokeLinecap="round"
                  />
                </svg>
              </div>
              <p className="mx-auto max-w-md text-base font-medium leading-relaxed text-gray-200">
                Drag &amp; drop audio and a cover image, or tap to browse
              </p>
              <p className="mt-3 text-xs text-gray-500">
                One cover and one or more tracks. Free: MP3 ≤50&nbsp;MB. Pro: WAV/FLAC ≤500&nbsp;MB.
              </p>
            </div>
          </FileHitArea>
        </div>
      </div>
    </div>
  );
}