Move old backend code to old_src folder

Signed-off-by: David Mehren <git@herrmehren.de>

old_src/lib/workers/dmpWorker.ts

@@ -0,0 +1,173 @@
+// external modules
+// eslint-disable-next-line @typescript-eslint/camelcase
+import { DIFF_DELETE, DIFF_INSERT, diff_match_patch, patch_obj } from 'diff-match-patch'
+import { Revision } from '../models'
+
+// Function for suppressing TS2722
+// eslint-disable-next-line @typescript-eslint/unbound-method,@typescript-eslint/no-empty-function
+function processSend (options): boolean {
+  if (process?.send !== undefined) {
+    return process.send(options)
+  }
+  return false
+}
+
+// We can't use the logger directly, because we are in a distinct nodejs
+// process and the global instance of logger is not the one of the parent. In
+// particular, it does not have the log level set correctly.
+function log (level: string, msg, ...splat): boolean {
+  return processSend({
+    msg: 'log',
+    level: level,
+    result: [msg, splat],
+    cacheKey: 1 // dummy value
+  })
+}
+// eslint-disable-next-line @typescript-eslint/camelcase,new-cap
+const dmp: diff_match_patch = new diff_match_patch()
+
+// eslint-disable-next-line @typescript-eslint/camelcase
+function getRevision (revisions: Revision[], count: number): { content: string; patch: patch_obj[]; authorship: string } {
+  const msStart = (new Date()).getTime()
+  let startContent = ''
+  let lastPatch = ''
+  // eslint-disable-next-line @typescript-eslint/camelcase
+  let applyPatches: patch_obj[] = []
+  let authorship = ''
+  if (count <= Math.round(revisions.length / 2)) {
+    // start from top to target
+    for (let i = 0; i < count; i++) {
+      const revision = revisions[i]
+      if (i === 0) {
+        startContent = revision.content || revision.lastContent
+      }
+      if (i !== count - 1) {
+        // eslint-disable-next-line @typescript-eslint/camelcase
+        const patch: patch_obj[] = dmp.patch_fromText(revision.patch)
+        applyPatches = applyPatches.concat(patch)
+      }
+      lastPatch = revision.patch
+      authorship = revision.authorship
+    }
+    // swap DIFF_INSERT and DIFF_DELETE to achieve unpatching
+    for (let i = 0, l = applyPatches.length; i < l; i++) {
+      for (let j = 0, m = applyPatches[i].diffs.length; j < m; j++) {
+        const diff = applyPatches[i].diffs[j]
+        if (diff[0] === DIFF_INSERT) {
+          diff[0] = DIFF_DELETE
+        } else if (diff[0] === DIFF_DELETE) {
+          diff[0] = DIFF_INSERT
+        }
+      }
+    }
+  } else {
+    // start from bottom to target
+    const l = revisions.length - 1
+    for (let i = l; i >= count - 1; i--) {
+      const revision = revisions[i]
+      if (i === l) {
+        startContent = revision.lastContent
+        authorship = revision.authorship
+      }
+      if (revision.patch) {
+        // eslint-disable-next-line @typescript-eslint/camelcase
+        const patch: patch_obj[] = dmp.patch_fromText(revision.patch)
+        applyPatches = applyPatches.concat(patch)
+      }
+      lastPatch = revision.patch
+      authorship = revision.authorship
+    }
+  }
+  let finalContent = ''
+  try {
+    finalContent = dmp.patch_apply(applyPatches, startContent)[0]
+  } catch (err) {
+    throw new Error(err)
+  }
+  const data = {
+    content: finalContent,
+    patch: dmp.patch_fromText(lastPatch),
+    authorship: authorship
+  }
+  const msEnd = (new Date()).getTime()
+  log('debug', (msEnd - msStart) + 'ms')
+  return data
+}
+
+function createPatch (lastDoc: string, currDoc: string): string {
+  const msStart = (new Date()).getTime()
+  const diff = dmp.diff_main(lastDoc, currDoc)
+  // eslint-disable-next-line @typescript-eslint/camelcase
+  const patch: patch_obj[] = dmp.patch_make(lastDoc, diff)
+  const strPatch: string = dmp.patch_toText(patch)
+  const msEnd = (new Date()).getTime()
+  log('debug', strPatch)
+  log('debug', (msEnd - msStart) + 'ms')
+  return strPatch
+}
+
+class Data {
+  msg: string
+  cacheKey: string
+  lastDoc?: string
+  currDoc?: string
+  revisions?: Revision[]
+  count?: number
+}
+
+process.on('message', function (data: Data) {
+  if (!data || !data.msg || !data.cacheKey) {
+    return log('error', 'dmp worker error: not enough data')
+  }
+  switch (data.msg) {
+    case 'create patch':
+      if (data.lastDoc === undefined || data.currDoc === undefined) {
+        return log('error', 'dmp worker error: not enough data on create patch')
+      }
+      try {
+        const patch: string = createPatch(data.lastDoc, data.currDoc)
+        processSend({
+          msg: 'check',
+          result: patch,
+          cacheKey: data.cacheKey
+        })
+      } catch (err) {
+        log('error', 'create patch: dmp worker error', err)
+        processSend({
+          msg: 'error',
+          error: err,
+          cacheKey: data.cacheKey
+        })
+      }
+      break
+    case 'get revision':
+      if (data.revisions === undefined || data.count === undefined) {
+        return log('error', 'dmp worker error: not enough data on get revision')
+      }
+      try {
+      // eslint-disable-next-line @typescript-eslint/camelcase
+        const result: { content: string; patch: patch_obj[]; authorship: string } = getRevision(data.revisions, data.count)
+        processSend({
+          msg: 'check',
+          result: result,
+          cacheKey: data.cacheKey
+        })
+      } catch (err) {
+        log('error', 'get revision: dmp worker error', err)
+        processSend({
+          msg: 'error',
+          error: err,
+          cacheKey: data.cacheKey
+        })
+      }
+      break
+  }
+})
+
+// log uncaught exception
+process.on('uncaughtException', function (err: Error) {
+  log('error', 'An uncaught exception has occured.')
+  log('error', err)
+  log('error', 'Process will exit now.')
+  process.exit(1)
+})