move organization of sheets in preparation for per-actor-type sheets

module/sheets/base-sheet.js

@@ -0,0 +1,70 @@
+import DG from "../config.js";
+
+const HbsAppMixin = foundry.applications.api.HandlebarsApplicationMixin;
+
+const DGSheetMixin = (Base) => {
+  return class DGDocumentSheet extends HbsAppMixin(Base) {
+    /** @inheritdoc */
+    static DEFAULT_OPTIONS = /** @type {const} */ ({
+      window: { resizable: true },
+      classes: [DG.ID, "sheet"],
+      form: { submitOnChange: true },
+    });
+
+    /** @inheritdoc */
+    static TEMPLATE_PATH = /** @type {const} */ (`systems/${DG.ID}/templates`);
+
+    static get THEME() {
+      return game.settings.get(DG.ID, "characterSheetStyle");
+    }
+
+    get THEME() {
+      return this.constructor.THEME;
+    }
+
+    /** @inheritdoc */
+    async _prepareContext(options) {
+      const context = await super._prepareContext(options);
+      const docName = this.document.documentName.toLowerCase();
+
+      // Add the document to the context under a descriptive name (i.e. "actor", "item")
+      context[docName] = this.document;
+
+      return context;
+    }
+    /** @inheritdoc */
+
+    async _onFirstRender(context, options) {
+      await super._onFirstRender(context, options);
+
+      const html = this.element;
+      html
+        .querySelector(".window-content")
+        .classList.add(`${this.THEME}-style`);
+    }
+
+    /** @inheritdoc */
+    async _onRender(context, options) {
+      await super._onRender(context, options);
+
+      const html = this.element;
+
+      // Double-click resize handle to reset sheet to original size.
+      html
+        .querySelector(".window-resize-handle")
+        .addEventListener("dblclick", () => {
+          this.resetPosition();
+        });
+    }
+
+    /**
+     * Resets the window's position to its default, as specified in the Sheet's options.
+     * @returns {void}
+     */
+    resetPosition() {
+      this.setPosition(this.options.position);
+    }
+  };
+};
+
+export default DGSheetMixin;