wip code preview thing

src/modules/codePreviews.js

@@ -0,0 +1,100 @@
+const events = require("../lib/events.js");
+const {hasFlag} = require("../lib/guildSettings.js");
+
+const REGEX_GITHUB =
+  /(?:\s|^)https?:\/\/(www\.)?github\.com\/.+?\/.+?\/blob\/([a-zA-Z0-9-_.#/]*)/g;
+const REGEX_GITLAB =
+  /(?:\s|^)https?:\/\/(www\.)?gitlab\.com\/.+?\/.+?\/-\/blob\/([a-zA-Z0-9-_.#/]*)/g;
+const REGEX_GITEA =
+  /(?:\s|^)https?:\/\/.+?\/.+?\/.+?\/src\/branch\/([a-zA-Z0-9-_.#/]*)/g;
+
+function unindent(str) {
+  str = str.replace(/\t/g, "    ");
+  const minIndent =
+    str
+      .match(/^ *(?=\S)/gm)
+      ?.reduce((prev, curr) => Math.min(prev, curr.length), Infinity) ?? 0;
+  if (!minIndent) return str;
+  return str.replace(new RegExp(`^ {${minIndent}}`, "gm"), "");
+}
+
+events.add("messageCreate", "codePreviews", async function (msg) {
+  if (!msg.guildID) return;
+  if (!hasFlag(msg.guildID, "codePreviews")) return;
+
+  let out = "";
+
+  const githubLinks = msg.content.match(REGEX_GITHUB);
+  const gitlabLinks = msg.content.match(REGEX_GITLAB);
+  const giteaLinks = msg.content.match(REGEX_GITEA);
+
+  for (const link of githubLinks) {
+    const rawLink = link.replace("/blob/", "/raw/");
+    const file = await fetch(rawLink).then((res) => res.text());
+    const lines = file.replace(/\r/g, "").split("\n");
+
+    const fileName = link.substring(
+      link.lastIndexOf("/") + 1,
+      link.indexOf("#") == -1 ? link.length : link.indexOf("#")
+    );
+    const fileType =
+      fileName.indexOf(".") == -1
+        ? ""
+        : fileName.subString(fileName.indexOf(".") + 1);
+
+    const lineStr = link.match(/#L\d+?(-L\d+?)?/)[0];
+    let startLine, endLine;
+    let entireFile = false;
+
+    if (lineStr) {
+      let [start, end] = link.match(/L\d+?/g);
+      start = parseInt(start.replace("L", ""));
+      if (!end) {
+        startLine = endLine = start;
+      } else {
+        end = parseInt(end.replace("L", ""));
+        startLine = start;
+        endLine = end;
+      }
+    } else {
+      entireFile = true;
+      startLine = 1;
+      endLine = lines.length;
+    }
+
+    const whichLines = entireFile
+      ? ""
+      : startLine == endLine
+      ? "Line " + startLine
+      : "Lines " + startLine + "-" + endLine;
+
+    startLine--;
+    endLine--;
+
+    const targetLines = (
+      entireFile ? lines : lines.slice(startLine, endLine)
+    ).join("\n");
+
+    out +=
+      "**" +
+      fileName +
+      ": **" +
+      whichLines +
+      "\n```" +
+      fileType +
+      "\n" +
+      unindent(targetLines) +
+      "\n```\n";
+  }
+
+  if (out !== "")
+    msg.channel.createMessage({
+      content: out,
+      allowedMentions: {
+        repliedUser: false,
+      },
+      messageReference: {
+        messageID: msg.id,
+      },
+    });
+});