DEV: Add a CSV importer for restoring deleted users (#12147)

This is an importer I wrote to restore some users that were
accidentally deleted for being purged as old staged users or old
unactivated users.

It reads from CSV files exported from a discourse sql backup.

script/import_scripts/csv_restore_staged_users.rb

@@ -0,0 +1,96 @@
+# frozen_string_literal: true
+
+require "csv"
+require File.expand_path(File.dirname(__FILE__) + "/base.rb")
+
+# Edit the constants and initialize method for your import data.
+
+class ImportScripts::CsvRestoreStagedUsers < ImportScripts::Base
+
+  CSV_FILE_PATH = ENV['CSV_USER_FILE']
+  CSV_CUSTOM_FIELDS = ENV['CSV_CUSTOM_FIELDS']
+  CSV_EMAILS = ENV['CSV_EMAILS']
+
+  BATCH_SIZE ||= 1000
+
+  def initialize
+    super
+
+    @imported_users = load_csv(CSV_FILE_PATH)
+    @imported_emails = load_csv(CSV_EMAILS)
+    @imported_custom_fields = load_csv(CSV_CUSTOM_FIELDS)
+    @skip_updates = true
+  end
+
+  def execute
+    puts "", "Importing from CSV file..."
+
+    import_users
+
+    puts "", "Done"
+  end
+
+  def load_csv(path)
+    CSV.parse(File.read(path), headers: true)
+  end
+
+  def username_for(name)
+    result = name.downcase.gsub(/[^a-z0-9\-\_]/, '')
+
+    if result.blank?
+      result = Digest::SHA1.hexdigest(name)[0...10]
+    end
+
+    result
+  end
+
+  def get_email(id)
+    email = nil
+    @imported_emails.each do |e|
+      if e["user_id"] == id
+        email = e["email"]
+      end
+    end
+    email
+  end
+
+  def get_custom_fields(id)
+    custom_fields = {}
+    @imported_custom_fields.each do |cf|
+      if cf["user_id"] == id
+        custom_fields[cf["name"]] = cf["value"]
+      end
+    end
+    custom_fields
+  end
+
+  def import_users
+    puts '', "Importing users"
+
+    users = []
+    @imported_users.each do |u|
+      email = get_email(u['id'])
+      custom_fields = get_custom_fields(u['id'])
+      u['email'] = email
+      u['custom_fields'] = custom_fields
+      users << u
+    end
+    users.uniq!
+
+    create_users(users) do |u|
+      {
+        id: u['id'],
+        username: u['username'],
+        email: u['email'],
+        created_at: u['created_at'],
+        staged: u['staged'],
+        custom_fields: u['custom_fields'],
+      }
+    end
+  end
+
+end
+
+if __FILE__ == $0
+  ImportScripts::CsvRestoreStagedUsers.new.perform
+end