add js to quote part of a post

data/static/js/thread.js

@@ -8,6 +8,125 @@
       ta.focus();
     })
   }
+
+  function supportsPopover() {
+    return Object.hasOwn(HTMLElement.prototype, "popover");
+  }
+
+  if (supportsPopover()){
+    let quotedPostContainer = null;
+    function isQuoteSelectionValid() {
+      const selection = document.getSelection();
+
+      if (!selection || selection.rangeCount === 0 || selection.isCollapsed) {
+        return false;
+      }
+
+      const range = selection.getRangeAt(0);
+      const commonAncestor = range.commonAncestorContainer;
+
+      const ancestorElement = commonAncestor.nodeType === Node.TEXT_NODE
+      ? commonAncestor.parentNode
+      : commonAncestor;
+
+      const container = ancestorElement.closest(".post-inner");
+      if (!container) {
+        return false;
+      }
+      const success = container.contains(ancestorElement);
+      if (success) {
+        quotedPostContainer = container;
+      }
+      return success;
+    }
+
+    let quotePopover = null;
+    let isSelecting = false;
+
+    document.addEventListener("mousedown", () => {
+      isSelecting = true;
+    })
+
+    document.addEventListener("mouseup", () => {
+      isSelecting = false;
+      handlePossibleSelection();
+    })
+
+    document.addEventListener("keyup", (e) => {
+      if (e.shiftKey && (e.key.startsWith('Arrow') || e.key === 'Home' || e.key === 'End')) {
+        handlePossibleSelection();
+      }
+    })
+
+    function handlePossibleSelection() {
+      setTimeout(() => {
+        const valid = isQuoteSelectionValid();
+        if (isSelecting || !valid) {
+          removePopover();
+          return;
+        }
+
+        const selection = document.getSelection();
+        const selectionStr = selection.toString().trim();
+        if (selection.isCollapsed || selectionStr === "") {
+          removePopover();
+          return;
+        }
+
+        showPopover();
+      }, 50)
+    }
+
+    function removePopover() {
+      quotePopover?.hidePopover();
+    }
+
+    function createPopover() {
+      quotePopover = document.createElement("div");
+      quotePopover.popover = "auto";
+      quotePopover.className = "quote-popover";
+
+      const quoteButton = document.createElement("button");
+      quoteButton.textContent = "Quote fragment"
+      quoteButton.className = "reduced"
+      quotePopover.appendChild(quoteButton);
+
+      document.body.appendChild(quotePopover);
+      return quoteButton;
+    }
+
+    function showPopover() {
+      if (!quotePopover) {
+        const quoteButton = createPopover();
+        quoteButton.addEventListener("click", () => {
+          console.log("Quoting:", document.getSelection().toString());
+          const postPermalink = quotedPostContainer.dataset.postPermalink;
+          const authorUsername = quotedPostContainer.dataset.authorUsername;
+          console.log(postPermalink, authorUsername);
+          if (ta.value.trim() !== "") {
+            ta.value += "\n"
+          }
+          ta.value += `[url=${postPermalink}]${authorUsername} said:[/url]\n[quote]${document.getSelection().toString()}[/quote]\n`;
+          ta.scrollIntoView()
+          ta.focus();
+
+          document.getSelection().empty();
+          removePopover();
+        })
+      }
+
+      const range = document.getSelection().getRangeAt(0);
+      const rect = range.getBoundingClientRect();
+      const scrollY = window.scrollY || window.pageYOffset;
+
+      quotePopover.style.setProperty("top", `${rect.top + scrollY - 55}px`)
+      quotePopover.style.setProperty("left", `${rect.left + rect.width/2}px`)
+
+      if (!quotePopover.matches(':popover-open')) {
+        quotePopover.showPopover();
+      }
+    }
+  }
   
   const deleteDialog = document.getElementById("delete-dialog");
   const deleteDialogCloseButton = document.getElementById("post-delete-dialog-close");