hedgedoc/old_src/lib/workers/dmpWorker.ts
David Mehren 7b9f9a487b
Move old backend code to old_src folder
Signed-off-by: David Mehren <git@herrmehren.de>
2020-08-20 19:43:05 +02:00

173 lines
5.4 KiB
TypeScript

// 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)
})