#!/usr/bin/env node

/**
 * @fileoverview
 * Utilities for interfacing with Transifex API 3.
 */

const transifexApi = require('@transifex/api').transifexApi;
const download = require('download');

/**
 * @import {Collection, JsonApiResource} from '@transifex/api';
 */

const ORG_NAME = 'llk';
const SOURCE_LOCALE = 'en';

try {
    transifexApi.setup({
        auth: process.env.TX_TOKEN
    });
} catch (err) {
    if (!process.env.TX_TOKEN) {
        throw new Error('TX_TOKEN is not defined.');
    }
    throw err;
}

/*
 * The Transifex JS API wraps the Transifex JSON API, and is built around the concept of a `Collection`.
 * A `Collection` begins as a URL builder: methods like `filter` and `sort` add query parameters to the URL.
 * The `download` method doesn't actually download anything: it returns the built URL. It seems to be intended
 * primarily for internal use, but shows up in the documentation despite not being advertised in the .d.ts file.
 * The `download` method is mainly used to skip the `fetch` method in favor of downloading the resource yourself.
 * The `fetch` method sends a request to the URL and returns a promise that resolves to the first page of results.
 * If there's only one page of results, the `data` property of the collection object will be an array of all results.
 * However, if there are multiple pages of results, the `data` property will only contain the first page of results.
 * Previous versions of this code would unsafely assume that the `data` property contained all results.
 * The `all` method returns an async iterator that yields all results, fetching additional pages as needed.
 */

/**
 * Collects all resources from all pages of a potentially-paginated Transifex collection.
 * It's not necessary, but also not harmful, to call `fetch()` on the collection before calling this function.
 * @param {Collection} collection A collection of Transifex resources.
 * @returns {Promise<JsonApiResource[]>} An array of all resources in the collection.
 */
const collectAll = async function (collection) {
    await collection.fetch(); // fetch the first page if it hasn't already been fetched
    const collected = [];
    for await (const item of collection.all()) {
        collected.push(item);
    }
    return collected;
};

/**
 * Creates a download event for a specific project, resource, and locale.
 * Returns the URL to download the resource.
 * @param {string} projectSlug - project slug (for example,  "scratch-editor")
 * @param {string} resourceSlug - resource slug (for example,  "blocks")
 * @param {string} localeCode - language code (for example,  "ko")
 * @param {string} mode - translation status of strings to include
 * @returns {Promise<string>} - URL to download the resource
 */
const getResourceLocation = async function (projectSlug, resourceSlug, localeCode, mode = 'default') {
    const resource = {
        data: {
            id: `o:${ORG_NAME}:p:${projectSlug}:r:${resourceSlug}`,
            type: 'resources'
        }
    };

    // if locale is English, create a download event of the source file
    if (localeCode === SOURCE_LOCALE) {
        return await transifexApi.ResourceStringsAsyncDownload.download({
            resource
        });
    }

    const language = {
        data: {
            id: `l:${localeCode}`,
            type: 'languages'
        }
    };

    // if locale is not English, create a download event of the translation file
    return await transifexApi.ResourceTranslationsAsyncDownload.download({
        mode,
        resource,
        language
    });
};

/**
 * Pulls a translation json from transifex, for a specific project, resource, and locale.
 * @param {string} project - project slug (for example,  "scratch-editor")
 * @param {string} resource - resource slug (for example,  "blocks")
 * @param {string} locale - language code (for example,  "ko")
 * @param {string} mode - translation status of strings to include
 * @returns {Promise<object>} - JSON object of translated resource strings (or, of the original resource
 * strings, if the local is the source language)
 */
const txPull = async function (project, resource, locale, mode = 'default') {
    let buffer;
    try {
        const url = await getResourceLocation(project, resource, locale, mode);
        for (let i = 0; i < 5; i++) {
            if (i > 0) {
                console.log(`Retrying txPull download after ${i} failed attempt(s)`);
            }
            try {
                buffer = await download(url); // might throw(?)
                break;
            } catch (e) {
                console.error(e, {project, resource, locale, buffer});
            }
        }
        if (!buffer) {
            throw Error(`txPull download failed after 5 retries: ${url}`);
        }
        buffer = buffer.toString();
        return JSON.parse(buffer);
    } catch (e) {
        e.cause = {
            project,
            resource,
            locale,
            buffer
        };
        throw e;
    }
};

/**
 * Given a project, returns a list of the slugs of all resources in the project
 * @param {string} project - project slug (for example,  "scratch-website")
 * @returns {Promise<array>} - array of strings, slugs identifying each resource in the project
 */
const txResources = async function (project) {
    const resources = transifexApi.Resource.filter({
        project: `o:${ORG_NAME}:p:${project}`
    });

    const resourcesData = await collectAll(resources);

    const slugs = resourcesData.map(r =>
        // r.id is a longer id string, like "o:llk:p:scratch-website:r:about-l10njson"
        // We just want the slug that comes after ":r:" ("about-l10njson")
        r.id.split(':r:')[1]
    );
    return slugs;
};

/**
 * @param {string} project - project slug (for example)
 * @returns {Promise<JsonApiResource[]>} - array of resource objects
 */
const txResourcesObjects = async function (project) {
    const resources = transifexApi.Resource.filter({
        project: `o:${ORG_NAME}:p:${project}`
    });

    return collectAll(resources);
};

/**
 * Gets available languages for a project
 * @param {string} slug - project slug (for example, "scratch-editor")
 * @returns {Promise<string[]>} - list of language codes
 */
const txAvailableLanguages = async function (slug) {
    const project = await transifexApi.Project.get({
        organization: `o:${ORG_NAME}`,
        slug: slug
    });

    const languages = await project.fetch('languages');
    const languagesData = await collectAll(languages);
    return languagesData.map(l => l.attributes.code);
};

/**
 * Uploads English source strings to a resource in transifex
 * @param {string} project - project slug (for example,  "scratch-editor")
 * @param {string} resource - resource slug (for example,  "blocks")
 * @param {object} sourceStrings - json of source strings
 */
const txPush = async function (project, resource, sourceStrings) {
    const resourceObj = {
        data: {
            id: `o:${ORG_NAME}:p:${project}:r:${resource}`,
            type: 'resources'
        }
    };

    await transifexApi.ResourceStringsAsyncUpload.upload({
        resource: resourceObj,
        content: JSON.stringify(sourceStrings)
    });
};

/**
 * Creates a new resource, and then uploads source strings to it if they are provided
 * @param {string} project - project slug (for example,  "scratch-editor")
 * @param {object} resource - object of resource information
 * @param {string} resource.slug - resource slug (for example,  "blocks")
 * @param {string} resource.name - resource name
 * @param {string} resource.i18nType - i18n format id
 * @param {object} resource.sourceStrings - json object of source strings
 */
const txCreateResource = async function (project, {slug, name, i18nType, sourceStrings}) {
    const i18nFormat = {
        data: {
            id: i18nType || 'KEYVALUEJSON',
            type: 'i18n_formats'
        }
    };

    const projectObj = {
        data: {
            id: `o:${ORG_NAME}:p:${project}`,
            type: 'projects'
        }
    };

    await transifexApi.Resource.create({
        attributes: {slug: slug, name: name},
        relationships: {
            i18n_format: i18nFormat,
            project: projectObj
        }
    });

    if (sourceStrings) {
        await txPush(project, slug, sourceStrings);
    }
};

module.exports = {txPull, txPush, txResources, txResourcesObjects, txCreateResource, txAvailableLanguages};