// Copyright 2018 Google LLC.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import * as functions from 'firebase-functions'
import { DialogflowApp } from 'actions-on-google'
import * as Translate from '@google-cloud/translate'

const translate = new Translate({
    projectId: functions.config().firebase.projectId,
})

const actionMap = new Map()
actionMap.set('translate.text', translateText)

const languages = {
    'French': 'fr',
    'Russian': 'ru',
    'Spanish': 'es',
    'Japanese': 'ja',
    'Chinese': 'zh',
    'Dutch': 'nl',
    'English': 'en',
    'German': 'de',
    'Italian': 'it',
    'Korean': 'ko'
}

export const fulfill = functions.https.onRequest((request, response) => {
    const app = new DialogflowApp({request, response})
    app.handleRequest(actionMap)
})

function translateText(app) {
    let text = app.getArgument('text')
    let langTo = app.getArgument('lang-to')
    let langFrom = app.getArgument('lang-from')
    console.log(app.getContext('translate-text'))

    if (!text) {
        const arg = app.getContextArgument('translate-text', 'lastText')
        if (arg) { text = arg.value }
    }
    if (!langTo) {
        const arg = app.getContextArgument('translate-text', 'lastLangTo')
        if (arg) { langTo = arg.value }
    }
    if (!langFrom) {
        const arg = app.getContextArgument('translate-text', 'lastLangFrom')
        if (arg) { langFrom = arg.value }
        if (!langFrom) { langFrom = 'English' }
    }

    app.setContext('translate-text', 2, {
        lastText: text,
        lastLangTo: langTo,
        lastLangFrom: langFrom
    })

    console.log(`text: ${text}`)
    console.log(`lang-to: ${langTo}`)
    console.log(`lang-from: ${langFrom}`)

    if (!text) {
        ask(app, "What would you like to translate?")
    }
    else if (!langTo) {
        ask(app, "What language would you like to translate to?")
    }
    else {
        const options = { to: languages[langTo] }
        if (langFrom) {
            options['from'] = languages[langFrom]
        }

        translate.translate(text, options)
        .then(results => {
            const translation = results[0]
            console.log(`translation: ${translation}`)
            tell(app, translation)
        })
        .catch(error => {
            console.error(error)
            const message = "Sorry, I couldn't translate that."
            tell(app, message)
        })
    }
}

// Warning!  I'm using private APIs below to gain access to the data field
// in the Dialogflow response.

function tell(app, speech) {
    const res = app.buildResponse_(speech, false)
    res.data.slack = { text: speech }
    app.doResponse_(res, 200)
}

function ask(app, question) {
    const res = app.buildResponse_(question, true)
    res.data.slack = { text: question }
    app.doResponse_(res, 200)
}