import type { AttachmentView } from '@dorfteich/shared';
import { Extension } from '@tiptap/core';
import type { EditorState } from '@tiptap/pm/state';
import { Plugin, PluginKey } from '@tiptap/pm/state';
import { Decoration, DecorationSet } from '@tiptap/pm/view';
import type { EditorView } from '@tiptap/pm/view';

import i18n from '../i18n';
import { apiUploadFile } from '../lib/api';

declare module '@tiptap/core' {
  interface Commands<ReturnType> {
    imageUpload: {
      /** Uploads `file` and inserts an image node at the current selection
       * once it succeeds (toolbar "insert image" dialog, issue #28). */
      insertImageFile: (file: File) => ReturnType;
    };
  }
}

type UploadMeta =
  | { type: 'add'; id: string; pos: number }
  | { type: 'error'; id: string }
  | { type: 'remove'; id: string };

const uploadKey = new PluginKey<DecorationSet>('imageUpload');

function widgetFor(id: string, status: 'uploading' | 'error'): () => HTMLElement {
  return () => {
    const span = document.createElement('span');
    span.className =
      status === 'error' ? 'editor-image-upload editor-image-upload--error' : 'editor-image-upload';
    span.dataset.uploadId = id;
    span.textContent = i18n.t(status === 'error' ? 'image.uploadFailed' : 'image.uploading', {
      ns: 'editor',
    });
    return span;
  };
}

/** Current position of the in-flight decoration for `id`, mapped through
 * every local edit made while the upload request was in flight. */
function decorationAt(state: EditorState, id: string): number | null {
  const set = uploadKey.getState(state);
  const found = set?.find(0, state.doc.content.size, (spec) => spec.id === id);
  return found?.[0]?.from ?? null;
}

/**
 * Async image upload with an in-flight placeholder (issue #28). Uploaded
 * bytes only ever become a real `image` node in the document once the
 * upload has actually succeeded (`POST /ponds/:id/files`, issue #27) — the
 * in-flight state lives purely as a ProseMirror decoration (a widget, not a
 * document node), so a failed upload cannot leave a broken node behind: on
 * error the decoration is simply removed after a brief visible error state.
 */
export const ImageUpload = Extension.create<{ pondId: string }>({
  name: 'imageUpload',

  addOptions() {
    return { pondId: '' };
  },

  addCommands() {
    return {
      insertImageFile:
        (file: File) =>
        ({ view }) => {
          if (!this.options.pondId) return false;
          startUpload(view, this.options.pondId, file, view.state.selection.from);
          return true;
        },
    };
  },

  addProseMirrorPlugins() {
    const options = this.options;
    return [
      new Plugin({
        key: uploadKey,
        state: {
          init: () => DecorationSet.empty,
          apply(tr, set) {
            const mapped = set.map(tr.mapping, tr.doc);
            const meta = tr.getMeta(uploadKey) as UploadMeta | undefined;
            if (!meta) return mapped;
            if (meta.type === 'add') {
              return mapped.add(tr.doc, [
                Decoration.widget(meta.pos, widgetFor(meta.id, 'uploading'), {
                  id: meta.id,
                  side: -1,
                }),
              ]);
            }
            const existing = mapped.find(0, tr.doc.content.size, (spec) => spec.id === meta.id);
            const without = mapped.remove(existing);
            if (meta.type === 'error') {
              const at = existing[0]?.from ?? 0;
              return without.add(tr.doc, [
                Decoration.widget(at, widgetFor(meta.id, 'error'), { id: meta.id, side: -1 }),
              ]);
            }
            return without;
          },
        },
        props: {
          decorations(state) {
            return uploadKey.getState(state);
          },
          handlePaste(view, event) {
            const files = Array.from(event.clipboardData?.files ?? []).filter((file) =>
              file.type.startsWith('image/'),
            );
            if (files.length === 0) return false;
            const pos = view.state.selection.from;
            files.forEach((file) => startUpload(view, options.pondId, file, pos));
            return true;
          },
          handleDrop(view, event, _slice, moved) {
            if (moved) return false; // internal drag (e.g. reordering), not a file drop
            const files = Array.from(event.dataTransfer?.files ?? []).filter((file) =>
              file.type.startsWith('image/'),
            );
            if (files.length === 0) return false;
            event.preventDefault();
            const coords = view.posAtCoords({ left: event.clientX, top: event.clientY });
            const pos = coords?.pos ?? view.state.selection.from;
            files.forEach((file) => startUpload(view, options.pondId, file, pos));
            return true;
          },
        },
      }),
    ];
  },
});

const ERROR_VISIBLE_MS = 4000;

function startUpload(view: EditorView, pondId: string, file: File, pos: number): void {
  const id = crypto.randomUUID();
  view.dispatch(view.state.tr.setMeta(uploadKey, { type: 'add', id, pos }));

  apiUploadFile<AttachmentView>(`/ponds/${pondId}/files`, file)
    .then((attachment) => {
      if (view.isDestroyed) return;
      const at = decorationAt(view.state, id) ?? pos;
      const imageType = view.state.schema.nodes.image;
      if (!imageType) return;
      view.dispatch(
        view.state.tr
          .setMeta(uploadKey, { type: 'remove', id })
          .insert(at, imageType.create({ fileId: attachment.id, alt: '' })),
      );
    })
    .catch(() => {
      if (view.isDestroyed) return;
      view.dispatch(view.state.tr.setMeta(uploadKey, { type: 'error', id }));
      window.setTimeout(() => {
        if (view.isDestroyed) return;
        view.dispatch(view.state.tr.setMeta(uploadKey, { type: 'remove', id }));
      }, ERROR_VISIBLE_MS);
    });
}