Handle changed usernames in import script

scripts/export_users.js

@@ -9,15 +9,24 @@ const shouldGzip = process.argv.slice(2).includes("--gzip")
 const filename = "users_export.json" + (shouldGzip ? ".gz" : "")
 const target = pj(__dirname, targetDir, filename)
 
+async function progress(message, callback) {
+	process.stdout.write(message)
+	const result = await callback()
+	process.stdout.write("done.\n")
+	return result
+}
+
 ;(async () => {
-	const users = db.prepare("SELECT * FROM Users").all()
-	let data = Buffer.from(JSON.stringify(users), "utf8")
+	let data = await progress("Preparing export data... ", () => {
+		const users = db.prepare("SELECT * FROM Users").all()
+		return Buffer.from(JSON.stringify(users), "utf8")
+	})
 
 	if (shouldGzip) {
-		data = await p(gzip)(data)
+		data = await progress("Compressing... ", () => p(gzip)(data))
 	}
 
-	await fs.writeFile(target, data)
+	await progress("Writing file... ", () => fs.writeFile(target, data))
 
 	console.log(`Users exported to ${target}`)
 })()

scripts/import_users.js

@@ -4,6 +4,12 @@ const pj = require("path").join
 const db = require("../src/lib/db")
 const {request} = require("../src/lib/utils/request")
 
+async function progress(message, callback) {
+	process.stdout.write(message)
+	const result = await callback()
+	process.stdout.write("done.\n")
+	return result
+}
 
 ;(async () => {
 	const target = process.argv[2]
@@ -13,6 +19,7 @@ const {request} = require("../src/lib/utils/request")
 		process.exit(1)
 	}
 
+	// Resolve input to stream
 	if (target.match(/^https?:\/\//)) {
 		console.log("Seems to be a URL, requesting now. This could take a few minutes. Be patient.")
 		const ref = await request(target)
@@ -33,51 +40,75 @@ const {request} = require("../src/lib/utils/request")
 	}
 
 	// Read out the stream into a buffer
-	process.stdout.write("Reading data... ")
-	const buffers = []
-	usersStream.on("data", chunk => buffers.push(chunk))
-	await new Promise(resolve => usersStream.once("end", resolve))
-	const usersString = Buffer.concat(buffers).toString("utf8")
-	process.stdout.write("done.\n")
-
 	/** @type {{username: string, user_id: string, created: number, updated: number, updated_version: number, biography: string, post_count: number, following_count: number, followed_by_count: number, external_url: string, full_name: string, is_private: number, is_verified: number, profile_pic_url: string}[]} */
-	const incomingUsers = JSON.parse(usersString)
+	const incomingUsers = await progress("Reading data... ", async () => {
+		const buffers = []
+		usersStream.on("data", chunk => buffers.push(chunk))
+		await new Promise(resolve => usersStream.once("end", resolve))
+		const usersString = Buffer.concat(buffers).toString("utf8")
+		return JSON.parse(usersString)
+	})
 
-	process.stdout.write("Noting existing users... ")
-	const existing = new Map()
-	for (const row of db.prepare("SELECT user_id, updated, updated_version FROM Users").iterate()) {
-		existing.set(row.user_id, row)
-	}
-	process.stdout.write("done.\n")
+	// Note the existing users
+	const [existing, existingUsernames] = await progress("Noting existing users... ", () => {
+		const existing = new Map()
+		const existingUsernames = new Map()
+		for (const row of db.prepare("SELECT username, user_id, updated, updated_version FROM Users").iterate()) {
+			existing.set(row.user_id, row)
+			existingUsernames.set(row.username, row.user_id)
+		}
+		return [existing, existingUsernames]
+	})
 
+	// Prepare queries
 	const base =
 		"INTO Users (username,  user_id,  created,  updated,  updated_version,  biography,  post_count,  following_count,  followed_by_count,  external_url,  full_name,  is_private,  is_verified,  profile_pic_url) VALUES "
 		         +"(@username, @user_id, @created, @updated, @updated_version, @biography, @post_count, @following_count, @followed_by_count, @external_url, @full_name, @is_private, @is_verified, @profile_pic_url)"
 	const preparedReplace = db.prepare("REPLACE "+base)
 	const preparedInsert = db.prepare("INSERT "+base)
+	const preparedDeleteByUsername = db.prepare("DELETE FROM Users WHERE username = ?")
 
+	// Prepare counters
 	let newCount = 0
 	let overwrittenCount = 0
 	let skippedCount = 0
 
-	process.stdout.write("Importing into database... ")
-	db.transaction(() => {
-		for (const user of incomingUsers) {
-			if (existing.has(user.user_id)) {
-				const existingRow = existing.get(user.user_id)
-				if (existingRow.updated_version <= user.updated_version && existingRow.updated < user.updated) {
-					preparedReplace.run(user)
-					overwrittenCount++
+	// Import new data
+	await progress("Importing into database... ", () => {
+		db.transaction(() => {
+			for (const user of incomingUsers) {
+				if (existing.has(user.user_id)) {
+					const existingRow = existing.get(user.user_id)
+					if (existingRow.updated_version <= user.updated_version && existingRow.updated < user.updated) {
+						preparedReplace.run(user)
+						overwrittenCount++
+					} else {
+						skippedCount++
+					}
 				} else {
-					skippedCount++
+					if (existingUsernames.has(user.username)) {
+						/*
+							The new row's user ID has not been seen, but the new row's username is already used.
+							So somebody changed username at some point. Which person has the username now?
+							We'll look at timestamps and accept the later version.
+						*/
+						const existingRow = existing.get(existingUsernames.get(user.username))
+						if (existingRow.updated < user.updated) { // if the incoming copy has been updated more recently
+							preparedDeleteByUsername.run(user.username) // delete the existing copy
+							existing.delete(user.user_id)
+							existingUsernames.delete(user.username)
+							// proceed on to insert the new row
+						} else { // the existing copy has been updated more recently, so skip this import
+							skippedCount++
+							continue // ew
+						}
+					}
+					preparedInsert.run(user)
+					newCount++
 				}
-			} else {
-				preparedInsert.run(user)
-				newCount++
 			}
-		}
-	})()
-	process.stdout.write("done.\n")
+		})()
+	})
 
 	console.log(`Imported ${incomingUsers.length} entries (${newCount} new, ${overwrittenCount} overwritten, ${skippedCount} skipped)`)
 })()