Google auto complete

This is a mini-plugin for IntelliJ which adds Google search results to auto-complete menu. Absolutely useless and hipster thing to do but still a lot of fun. The main point though is that auto-completion contributors can be added and modified at runtime.

(Source code can be executed inside this plugin https://github.com/dkandalov/live-plugin)

import com.intellij.codeInsight.completion.*
import com.intellij.codeInsight.lookup.LookupElementBuilder
import com.intellij.lang.Language
import com.intellij.openapi.Disposable
import com.intellij.patterns.ElementPattern
import com.intellij.util.ProcessingContext
import groovy.json.JsonSlurper
import org.jetbrains.annotations.NotNull

import static com.intellij.codeInsight.completion.CompletionType.BASIC
import static com.intellij.patterns.PlatformPatterns.psiElement
import static liveplugin.PluginUtil.show

if (isIdeStartup) return

def groovy = Language.findLanguageByID("Groovy")
registerCompletionContributor(groovy, BASIC, psiElement(), pluginDisposable) { parameters, context, CompletionResultSet result ->
    def suggestions = googleSuggestionsFor(result.prefixMatcher.prefix).collect { toCamelHumps(it) }
    result.addAllElements(suggestions.collect { LookupElementBuilder.create(it) })
}
show("Loaded auto-completion contributors")


static registerCompletionContributor(Language language, CompletionType completionType, ElementPattern elementPattern, Disposable disposable, Closure callback) {
    CompletionContributor.INSTANCE.clearCache()

    def contributor = new CompletionContributor() {}
    contributor.extend(completionType, elementPattern, new CompletionProvider<CompletionParameters>() {
        @Override protected void addCompletions(@NotNull CompletionParameters parameters, ProcessingContext context, @NotNull CompletionResultSet result) {
            callback(parameters, context, result)
        }
    })
    CompletionContributor.INSTANCE.addExplicitExtension(language, contributor, disposable)
}

static List<String> googleSuggestionsFor(String text) {
    text = URLEncoder.encode(text, "UTF-8")
    def json = "https://suggestqueries.google.com/complete/search?client=firefox&q=$text".toURL().text
    new JsonSlurper().parseText(json)[1].toList()
}

static String toCamelHumps(String s) {
    def i = s.indexOf(" ")
    if (i == -1) s
    else {
        def beforeSpace = s[0..<i]
        def restOfString = (s.length() > i + 2 ? s[i + 2..-1] : "")
        toCamelHumps(beforeSpace + s[i + 1].toUpperCase() + restOfString)
    }
}