pro and smart conflict

pro/src/conflictLogic.ts

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+import isEqual from "lodash/isEqual";
+// import {
+//   makePatches,
+//   applyPatches,
+//   stringifyPatches,
+//   parsePatch,
+// } from "@sanity/diff-match-patch";
+import {
+  LCS,
+  diff3Merge,
+  diffComm,
+  diffPatch,
+  mergeDiff3,
+  mergeDigIn,
+  patch,
+} from "node-diff3";
+import type { Entity } from "../../src/baseTypes";
+import { copyFile } from "../../src/copyLogic";
+import type { FakeFs } from "../../src/fsAll";
+import { MERGABLE_SIZE } from "./baseTypesPro";
+
+export function isMergable(a: Entity, b?: Entity) {
+  if (b !== undefined && a.keyRaw !== b.keyRaw) {
+    return false;
+  }
+
+  return (
+    !a.keyRaw.endsWith("/") &&
+    a.sizeRaw <= MERGABLE_SIZE &&
+    (a.keyRaw.endsWith(".md") || a.keyRaw.endsWith(".markdown"))
+  );
+}
+
+/**
+ * slightly modify to adjust in markdown context
+ * @param a
+ * @param o
+ * @param b
+ */
+function mergeDigInModified(a: string, o: string, b: string) {
+  const { conflict, result } = mergeDigIn(a, o, b);
+  for (let index = 0; index < result.length; ++index) {
+    if (["<<<<<<<", "=======", ">>>>>>>"].contains(result[index])) {
+      result[index] = "`" + result[index] + "`";
+    }
+  }
+  return {
+    conflict,
+    result,
+  };
+}
+
+function getLCSText(a: string, b: string) {
+  const aa = a.split("\n");
+  const bb = b.split("\n");
+  let raw = LCS(aa, bb);
+
+  const k: string[] = [];
+
+  do {
+    k.unshift(aa[raw.buffer1index]);
+
+    raw = raw.chain as any;
+  } while (raw !== null && raw !== undefined && raw.buffer1index !== -1);
+
+  return k.join("\n");
+}
+
+/**
+ * It's tricky. We find LCS then pretend it's the original text
+ * @param a
+ * @param b
+ * @returns
+ */
+function twoWayMerge(a: string, b: string): string {
+  // const c = getLCSText(a, b);
+  // const patches = makePatches(c, a);
+  // const [d] = applyPatches(patches, b);
+  const c = getLCSText(a, b);
+  const d = mergeDigInModified(a, c, b).result.join("\n");
+  return d;
+}
+
+/**
+ * Originally three way merge.
+ * @param a
+ * @param b
+ * @param orig
+ * @returns
+ */
+function threeWayMerge(a: string, b: string, orig: string) {
+  return mergeDigInModified(a, orig, b).result.join("\n");
+}
+
+export async function mergeFile(
+  key: string,
+  left: FakeFs,
+  right: FakeFs,
+  contentOrig: ArrayBuffer | null | undefined
+) {
+  // console.debug(
+  //   `mergeFile: key=${key}, left=${left.kind}, right=${right.kind}`
+  // );
+  if (key.endsWith("/")) {
+    throw Error(`should not call ${key} in mergeFile`);
+  }
+
+  if (!key.endsWith(".md") && !key.endsWith(".markdown")) {
+    throw Error(`currently only support markdown files in mergeFile`);
+  }
+
+  const [contentLeft, contentRight] = await Promise.all([
+    left.readFile(key),
+    right.readFile(key),
+  ]);
+
+  let newArrayBuffer: ArrayBuffer | undefined = undefined;
+  const decoder = new TextDecoder("utf-8");
+
+  if (isEqual(contentLeft, contentRight)) {
+    // we are lucky enough
+    newArrayBuffer = contentLeft;
+    // TODO: save the write
+  } else {
+    if (contentOrig === null || contentOrig === undefined) {
+      const newText = twoWayMerge(
+        decoder.decode(contentLeft),
+        decoder.decode(contentRight)
+      );
+      // no need to worry about the offset here because the array is new and not sliced
+      newArrayBuffer = new TextEncoder().encode(newText).buffer;
+    } else {
+      const newText = threeWayMerge(
+        decoder.decode(contentLeft),
+        decoder.decode(contentRight),
+        decoder.decode(contentOrig)
+      );
+      newArrayBuffer = new TextEncoder().encode(newText).buffer;
+    }
+  }
+
+  const mtime = Date.now();
+
+  // left (local) must wait for the right
+  // because the mtime might be different after upload
+  // upload firstly
+  const rightEntity = await right.writeFile(key, newArrayBuffer, mtime, mtime);
+  // write local secondly
+  const leftEntity = await left.writeFile(
+    key,
+    newArrayBuffer,
+    rightEntity.mtimeCli ?? mtime,
+    rightEntity.mtimeCli ?? mtime
+  );
+
+  return {
+    entity: rightEntity,
+    content: newArrayBuffer,
+  };
+}
+
+export function getFileRename(key: string) {
+  if (
+    key === "" ||
+    key === "." ||
+    key === ".." ||
+    key === "/" ||
+    key.endsWith("/")
+  ) {
+    throw Error(`we cannot rename key=${key}`);
+  }
+
+  const segsPath = key.split("/");
+  const name = segsPath[segsPath.length - 1];
+  const segsName = name.split(".");
+
+  if (segsName.length === 0) {
+    throw Error(`we cannot rename key=${key}`);
+  } else if (segsName.length === 1) {
+    // name = "kkk" without any dot
+    segsPath[segsPath.length - 1] = `${name}.dup`;
+  } else if (segsName.length === 2) {
+    if (segsName[0] === "") {
+      // name = ".kkkk" with leading dot
+      segsPath[segsPath.length - 1] = `${name}.dup`;
+    } else if (segsName[1] === "") {
+      // name = "kkkk." with tailing dot
+      segsPath[segsPath.length - 1] = `${segsName[0]}.dup`;
+    } else {
+      // name = "aaa.bbb" normally
+      segsPath[segsPath.length - 1] = `${segsName[0]}.dup.${segsName[1]}`;
+    }
+  } else {
+    // name = "[...].bbb.ccc"
+    const firstPart = segsName.slice(0, segsName.length - 1).join(".");
+    const thirdPart = segsName[segsName.length - 1];
+    segsPath[segsPath.length - 1] = `${firstPart}.dup.${thirdPart}`;
+  }
+  const res = segsPath.join("/");
+  return res;
+}
+
+/**
+ * local: x.md -> x.dup.md -> upload to remote
+ * remote: x.md -> download to local -> using original name x.md
+ */
+export async function duplicateFile(
+  key: string,
+  left: FakeFs,
+  right: FakeFs,
+  uploadCallback: (entity: Entity) => Promise<any>,
+  downloadCallback: (entity: Entity) => Promise<any>
+) {
+  let key2 = getFileRename(key);
+  let usable = false;
+  do {
+    try {
+      const s = await left.stat(key2);
+      if (s === null || s === undefined) {
+        throw Error(`not exist $${key2}`);
+      }
+      console.debug(`key2=${key2} exists, cannot use for new file`);
+      key2 = getFileRename(key2);
+      console.debug(`key2=${key2} is prepared for next try`);
+    } catch (e) {
+      // not exists, exactly what we want
+      console.debug(`key2=${key2} doesn't exist, usable for new file`);
+      usable = true;
+    }
+  } while (!usable);
+  await left.rename(key, key2);
+
+  /**
+   * x.dup.md -> upload to remote
+   */
+  async function f1() {
+    const k = await copyFile(key2, left, right);
+    await uploadCallback(k.entity);
+    return k.entity;
+  }
+
+  /**
+   * x.md -> download to local
+   */
+  async function f2() {
+    const k = await copyFile(key, right, left);
+    await downloadCallback(k.entity);
+    return k.entity;
+  }
+
+  const [resUpload, resDownload] = await Promise.all([f1(), f2()]);
+
+  return {
+    upload: resUpload,
+    download: resDownload,
+  };
+}