Hope this is not a disaster

.editorconfig

@@ -0,0 +1,6 @@
+[*]
+end_of_line = lf
+indent_size = 2
+indent_style = space
+trim_trailing_whitespace = true
+insert_final_newline = true

.gitignore

@@ -1,3 +1,5 @@
 node_modules/
 tmp/
-.DS_Store
+.DS_Store
+.rpt2_cache
+cache/

dist/addon/insert-file.js

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+(function (global, factory) {
+  typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports, require('codemirror'), require('hypermd'), require('../../hypermd/addon/readlink')) :
+  typeof define === 'function' && define.amd ? define(['exports', 'codemirror', 'hypermd', '../../hypermd/addon/readlink'], factory) :
+  (factory((global.HyperMD = global.HyperMD || {}, global.HyperMD.InsertFile = {}),global.CodeMirror,global.HyperMD));
+}(this, (function (exports,CodeMirror,hypermd) { 'use strict';
+
+  CodeMirror = CodeMirror && CodeMirror.hasOwnProperty('default') ? CodeMirror['default'] : CodeMirror;
+
+  // HyperMD, copyright (c) by laobubu
+  /** a spinning gif image (16x16) */
+  var spinGIF = '';
+  var errorPNG = '';
+  /**
+   * send data to url
+   *
+   * @param method default: "POST"
+   */
+  function ajaxUpload(url, form, callback, method) {
+      var xhr = new XMLHttpRequest();
+      var formData = new FormData();
+      for (var name in form)
+          { formData.append(name, form[name]); }
+      xhr.onreadystatechange = function () {
+          if (4 == this.readyState) {
+              var ret = xhr.responseText;
+              try {
+                  ret = JSON.parse(xhr.responseText);
+              }
+              catch (err) { }
+              if (/^20\d/.test(xhr.status + "")) {
+                  callback(ret, null);
+              }
+              else {
+                  callback(null, ret);
+              }
+          }
+      };
+      xhr.open(method || 'POST', url, true);
+      // xhr.setRequestHeader("Content-Type", "multipart/form-data");
+      xhr.send(formData);
+  }
+  /**
+   * Default FileHandler
+   *
+   * accepts images, uploads to https://sm.ms and inserts as `![](image_url)`
+   */
+  var DefaultFileHandler = function (files, action) {
+      var unfinishedCount = 0;
+      var placeholderForAll = document.createElement("div");
+      placeholderForAll.className = "HyperMD-insertFile-dfh-placeholder";
+      action.setPlaceholder(placeholderForAll);
+      /** @type {{name:string, url:string, placeholder:HTMLImageElement, blobURL:string}[]} */
+      var uploads = [];
+      var supportBlobURL = typeof URL !== 'undefined';
+      for (var i = 0; i < files.length; i++) {
+          var file = files[i];
+          if (!/image\//.test(file.type))
+              { continue; }
+          var blobURL = supportBlobURL ? URL.createObjectURL(file) : spinGIF;
+          var name = file.name.match(/[^\\\/]+\.\w+$/)[0];
+          var url = null;
+          var placeholder = document.createElement("img");
+          placeholder.onload = action.resize; // img size changed
+          placeholder.className = "HyperMD-insertFile-dfh-uploading";
+          placeholder.src = blobURL;
+          placeholderForAll.appendChild(placeholder);
+          uploads.push({
+              blobURL: blobURL, name: name, url: url, placeholder: placeholder,
+          });
+          unfinishedCount++;
+          // now start upload image. once uploaded, `finishImage(index, url)` shall be called
+          Upload_SmMs(file, uploads.length - 1);
+      }
+      return unfinishedCount > 0;
+      function finishImage(index, url) {
+          uploads[index].url = url;
+          var placeholder = uploads[index].placeholder;
+          placeholder.className = "HyperMD-insertFile-dfh-uploaded";
+          placeholder.src = url || errorPNG;
+          if (supportBlobURL)
+              { URL.revokeObjectURL(uploads[index].blobURL); }
+          if (--unfinishedCount === 0) {
+              var texts = uploads.map(function (it) { return ("![" + (it.name) + "](" + (it.url) + ")"); });
+              action.finish(texts.join("\n"));
+          }
+      }
+      function Upload_SmMs(file, index) {
+          ajaxUpload('https://sm.ms/api/upload', {
+              smfile: file,
+              format: 'json'
+          }, function (o, e) {
+              var imgURL = (o && o.code == 'success') ? o.data.url : null;
+              finishImage(index, imgURL);
+          });
+      }
+  };
+  var defaultOption = {
+      byDrop: true,
+      byPaste: true,
+      fileHandler: DefaultFileHandler,
+  };
+  var InsertFile = function(cm) {
+      var this$1 = this;
+
+      this.byPaste = defaultOption.byPaste;
+      this.byDrop = defaultOption.byDrop;
+      this.fileHandler = defaultOption.fileHandler;
+      this.pasteHandle = function (cm, ev) {
+          if (!this$1.doInsert(ev.clipboardData || window['clipboardData']))
+              { return; }
+          ev.preventDefault();
+      };
+      this.dropHandle = function (cm, ev) {
+          var self = this$1, cm = this$1.cm, result = false;
+          cm.operation(function () {
+              var pos = cm.coordsChar({ left: ev.clientX, top: ev.clientY });
+              cm.setCursor(pos);
+              result = self.doInsert(ev.dataTransfer);
+          });
+          if (!result)
+              { return; }
+          ev.preventDefault();
+      };
+      // Use FlipFlop to bind/unbind status
+      this.ff_paste = new hypermd.FlipFlop(
+      /* ON  */ function () { return this$1.cm.on("paste", this$1.pasteHandle); }, 
+      /* OFF */ function () { return this$1.cm.off("paste", this$1.pasteHandle); });
+      this.ff_drop = new hypermd.FlipFlop(
+      /* ON  */ function () { return this$1.cm.on("drop", this$1.pasteHandle); }, 
+      /* OFF */ function () { return this$1.cm.off("drop", this$1.pasteHandle); });
+      this.cm = cm;
+  };
+  /**
+   * upload files to the current cursor.
+   *
+   * @param {DataTransfer} data
+   * @returns {boolean} data is accepted or not
+   */
+  InsertFile.prototype.doInsert = function (data) {
+      var cm = this.cm;
+      if (!data || !data.files || 0 === data.files.length)
+          { return false; }
+      var files = data.files;
+      // only consider one format
+      var fileHandlers = (typeof this.fileHandler === 'function') ? [this.fileHandler] : this.fileHandler;
+      var handled = false;
+      cm.operation(function () {
+          var pos = cm.getCursor();
+          var placeholderContainer = document.createElement("span");
+          var marker = cm.markText(pos, pos, {
+              replacedWith: placeholderContainer,
+              clearOnEnter: false,
+              handleMouseEvents: false,
+          });
+          var action = {
+              finish: function (text, cursor) { return cm.operation(function () {
+                  pos = marker.find().from;
+                  cm.replaceRange(text, pos, pos);
+                  marker.clear();
+                  if (typeof cursor === 'number')
+                      { cm.setCursor({
+                          line: pos.line,
+                          ch: pos.ch + cursor,
+                      }); }
+              }); },
+              setPlaceholder: function (el) {
+                  if (placeholderContainer.childNodes.length > 0)
+                      { placeholderContainer.removeChild(placeholderContainer.firstChild); }
+                  placeholderContainer.appendChild(el);
+                  marker.changed();
+              },
+              resize: function() {
+                  marker.changed();
+              }
+          };
+          for (var i = 0; i < fileHandlers.length; i++) {
+              var fn = fileHandlers[i];
+              if (fn(files, action)) {
+                  handled = true;
+                  break;
+              }
+          }
+          if (!handled)
+              { marker.clear(); }
+      });
+      return handled;
+  };
+  /** HYPERMD ADDON DECLARATION */
+  var AddonAlias = "insertFile";
+  var AddonClassCtor = InsertFile;
+  var OptionName = "hmdInsertFile";
+  var getAddon = hypermd.Addon.Getter(AddonAlias, AddonClassCtor);
+  CodeMirror.defineOption(OptionName, false, function (cm, newVal) {
+      var enabled = !!newVal;
+      cm.hmd.insertFile;
+      if (!enabled || newVal === true) {
+          newVal = { byDrop: enabled, byPaste: enabled };
+      }
+      else if (typeof newVal === 'function' || newVal instanceof Array) {
+          newVal = { byDrop: enabled, byPaste: enabled, fileHandler: newVal };
+      }
+      else if (typeof newVal !== 'object') {
+          throw new Error("[HyperMD] wrong hmdInsertFile option value");
+      }
+      var newCfg = hypermd.Addon.migrateOption(newVal, defaultOption);
+      ///// apply config
+      var inst = getAddon(cm);
+      inst.ff_paste.setBool(newCfg.byPaste);
+      inst.ff_drop.setBool(newCfg.byDrop);
+      ///// write new values into cm
+      for (var k in defaultOption)
+          { inst[k] = newCfg[k]; }
+  });
+
+  exports.ajaxUpload = ajaxUpload;
+  exports.DefaultFileHandler = DefaultFileHandler;
+  exports.InsertFile = InsertFile;
+  exports.defaultOption = defaultOption;
+  exports.getAddon = getAddon;
+
+  Object.defineProperty(exports, '__esModule', { value: true });
+
+})));

dist/addon/readlink.js

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+(function (global, factory) {
+  typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports, require('codemirror'), require('hypermd')) :
+  typeof define === 'function' && define.amd ? define(['exports', 'codemirror', 'hypermd'], factory) :
+  (factory((global.HyperMD = global.HyperMD || {}, global.HyperMD.ReadLink = {}),global.CodeMirror,global.HyperMD));
+}(this, (function (exports,CodeMirror,hypermd) { 'use strict';
+
+  CodeMirror = CodeMirror && CodeMirror.hasOwnProperty('default') ? CodeMirror['default'] : CodeMirror;
+
+  // HyperMD, copyright (c) by laobubu
+  var ReadLink = function(cm) {
+      var this$1 = this;
+
+      this.cm = cm;
+      this.cache = {};
+      cm.on("changes", hypermd.debounce(function () { return this$1.rescan(); }, 500));
+      this.rescan();
+  };
+  /**
+   * get link footnote content like
+   *
+   * ```markdown
+   *  [icon]: http://laobubu.net/icon.png
+   * ```
+   *
+   * @param footNoteName case-insensive name, without "[" or "]"
+   * @param line     current line. if not set, the first definition will be returned
+   */
+  ReadLink.prototype.read = function (footNoteName, line) {
+      var defs = this.cache[footNoteName.trim().toLowerCase()] || [];
+      var def;
+      if (typeof line !== "number")
+          { line = 1e9; }
+      for (var i = 0; i < defs.length; i++) {
+          def = defs[i];
+          if (def.line > line)
+              { break; }
+      }
+      return def;
+  };
+  /**
+   * Scan content and rebuild the cache
+   */
+  ReadLink.prototype.rescan = function () {
+      var cm = this.cm;
+      var cache = (this.cache = {});
+      cm.eachLine(function (line) {
+          var txt = line.text, mat = /^(?:>\s+)*>?\s{0,3}\[([^\]]+)\]:\s*(.+)$/.exec(txt);
+          if (mat) {
+              var key = mat[1].trim().toLowerCase(), content = mat[2];
+              if (!cache[key])
+                  { cache[key] = []; }
+              cache[key].push({
+                  line: line.lineNo(),
+                  content: content,
+              });
+          }
+      });
+  };
+  /** HYPERMD ADDON DECLARATION */
+  var AddonAlias = "readLink";
+  var AddonClassCtor = ReadLink;
+  var getAddon = hypermd.Addon.Getter(AddonAlias, AddonClassCtor);
+  /** HYPERMD HELPER DECLARATION */
+  var HelperName = "hmdReadLink";
+  var HelperObject = function (footNoteName) {
+      return getAddon(this).read(footNoteName);
+  };
+  CodeMirror.defineExtension(HelperName, HelperObject);
+
+  exports.ReadLink = ReadLink;
+  exports.getAddon = getAddon;
+
+  Object.defineProperty(exports, '__esModule', { value: true });
+
+})));