"use client";

import { useRef, useState } from "react";
import { api } from "@/lib/client";
import { imageDescription, imageSrc, type GalleryImage, type ImageFile } from "@/lib/types";

/* Two related things in one panel:
 *  - files: what's in public/img/blog/<slug>/ (upload / delete / insert)
 *  - gallery: the post's images[] (ordered; the first is the card cover).
 * Uploading and deleting files happens immediately; gallery edits are part
 * of the post and are saved with it. */

type Props = {
  /** The saved slug; uploads are disabled until the post exists. */
  slug: string | null;
  files: ImageFile[];
  onFilesChange: (files: ImageFile[]) => void;
  gallery: GalleryImage[];
  onGalleryChange: (gallery: GalleryImage[]) => void;
  onInsert: (file: ImageFile) => void;
};

function formatSize(bytes: number): string {
  return bytes > 1024 * 1024 ? `${(bytes / 1024 / 1024).toFixed(1)} MB` : `${Math.ceil(bytes / 1024)} KB`;
}

function withDescription(src: string, description: string): GalleryImage {
  return description.trim() ? { src, description } : src;
}

export default function ImagePanel({ slug, files, onFilesChange, gallery, onGalleryChange, onInsert }: Props) {
  const inputRef = useRef<HTMLInputElement>(null);
  const [over, setOver] = useState(false);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<string | null>(null);

  const galleryIndex = (src: string) => gallery.findIndex((g) => imageSrc(g) === src);

  async function upload(list: FileList | File[]) {
    if (!slug || !list.length) return;
    const form = new FormData();
    for (const f of Array.from(list)) form.append("file", f);
    setBusy(true);
    setError(null);
    try {
      const res = await api<{ files: ImageFile[] }>(`/api/images/${slug}`, { method: "POST", body: form });
      onFilesChange(res.files);
    } catch (err) {
      setError((err as Error).message);
    } finally {
      setBusy(false);
    }
  }

  async function remove(file: ImageFile) {
    if (!slug || !window.confirm(`Delete ${file.name} from disk?`)) return;
    try {
      const res = await api<{ files: ImageFile[] }>(
        `/api/images/${slug}?name=${encodeURIComponent(file.name)}`,
        { method: "DELETE" }
      );
      onFilesChange(res.files);
      if (galleryIndex(file.src) >= 0) onGalleryChange(gallery.filter((g) => imageSrc(g) !== file.src));
    } catch (err) {
      setError((err as Error).message);
    }
  }

  function move(index: number, delta: number) {
    const next = [...gallery];
    const [item] = next.splice(index, 1);
    next.splice(index + delta, 0, item);
    onGalleryChange(next);
  }

  // Gallery entries pointing outside this post's folder (e.g. hand-added
  // paths) still need to be manageable, so list them too.
  const fileSrcs = new Set(files.map((f) => f.src));
  const external = gallery.filter((g) => !fileSrcs.has(imageSrc(g)));

  return (
    <section className="images">
      <h2>Images</h2>
      {error && <div className="notice error">{error}</div>}

      {gallery.length > 0 && (
        <>
          <p className="muted small">
            Gallery (shown below the post; the first image is also the card cover). Edits here are saved with the
            post.
          </p>
          <table className="list" style={{ marginBottom: 20 }}>
            <tbody>
              {gallery.map((img, i) => (
                <tr key={imageSrc(img)}>
                  <td className="mono small" style={{ width: 30 }}>
                    {i === 0 ? "cover" : i + 1}
                  </td>
                  <td style={{ width: 80 }}>
                    {/* eslint-disable-next-line @next/next/no-img-element */}
                    <img src={"/" + imageSrc(img)} alt="" style={{ height: 40, borderRadius: 4 }} />
                  </td>
                  <td className="mono small">{imageSrc(img)}</td>
                  <td>
                    <input
                      placeholder="description (alt text)"
                      value={imageDescription(img) ?? ""}
                      onChange={(e) =>
                        onGalleryChange(gallery.map((g, j) => (j === i ? withDescription(imageSrc(g), e.target.value) : g)))
                      }
                    />
                  </td>
                  <td className="actions">
                    <button type="button" className="ghost" disabled={i === 0} onClick={() => move(i, -1)} title="Move up">
                      ↑
                    </button>
                    <button
                      type="button"
                      className="ghost"
                      disabled={i === gallery.length - 1}
                      onClick={() => move(i, 1)}
                      title="Move down"
                    >
                      ↓
                    </button>
                    <button type="button" onClick={() => onGalleryChange(gallery.filter((_, j) => j !== i))}>
                      Remove
                    </button>
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
          {external.length > 0 && (
            <p className="muted small">
              {external.length} gallery image(s) live outside public/img/blog/{slug ?? "<slug>"}/.
            </p>
          )}
        </>
      )}

      {!slug ? (
        <div className="image-drop">Save the post once to enable image uploads.</div>
      ) : (
        <div
          className={`image-drop${over ? " over" : ""}`}
          onClick={() => inputRef.current?.click()}
          onDragOver={(e) => {
            e.preventDefault();
            setOver(true);
          }}
          onDragLeave={() => setOver(false)}
          onDrop={(e) => {
            e.preventDefault();
            setOver(false);
            upload(e.dataTransfer.files);
          }}
        >
          {busy ? "Uploading…" : `Drop images here or click to upload → public/img/blog/${slug}/`}
          <input
            ref={inputRef}
            type="file"
            multiple
            accept=".png,.jpg,.jpeg,.gif,.webp,.svg,.mp4"
            hidden
            onChange={(e) => {
              if (e.target.files) upload(e.target.files);
              e.target.value = "";
            }}
          />
        </div>
      )}

      <div className="image-grid">
        {files.map((file) => {
          const inGallery = galleryIndex(file.src) >= 0;
          return (
            <div key={file.name} className={`image-card${inGallery ? " in-gallery" : ""}`}>
              <div className="thumb">
                {/\.mp4$/i.test(file.name) ? (
                  <video src={"/" + file.src} muted />
                ) : (
                  // eslint-disable-next-line @next/next/no-img-element
                  <img src={"/" + file.src} alt={file.name} />
                )}
              </div>
              <div className="body">
                <div className="name">
                  {file.name} <span className="muted">· {formatSize(file.size)}</span>
                </div>
                <div className="row">
                  <button type="button" onClick={() => onInsert(file)} title="Insert at cursor in the body">
                    Insert
                  </button>
                  <button
                    type="button"
                    onClick={() =>
                      onGalleryChange(
                        inGallery ? gallery.filter((g) => imageSrc(g) !== file.src) : [...gallery, file.src]
                      )
                    }
                  >
                    {inGallery ? "− Gallery" : "+ Gallery"}
                  </button>
                  <button type="button" className="danger" onClick={() => remove(file)}>
                    Delete
                  </button>
                </div>
              </div>
            </div>
          );
        })}
      </div>
    </section>
  );
}