const compareTwoPages = async ({pageOneId, pageTwoId}) => {
    console.log(`Start read pages: ${pageOneId}; ${pageTwoId}`);

    const fileOnePromise = fsPromises.readFile(
        `pagesDir/${pageOneId}.html`,
        {encoding: 'utf8'}
    ).then((fileContent) => {
        console.log(`File read: pagesDir/${pageOneId}.html`);
        return fileContent;
    }).catch((error) => {
        console.error(`Cant read file: pagesDir/${pageOneId}.html`, error)
        throw new Error(`Cant read page: ${pageOneId}`);
    });

    const fileTwoPromise = fsPromises.readFile(
        `pagesDir/${pageTwoId}.html`,
        {encoding: 'utf8'}
    ).then((fileContent) => {
        console.log(`File read: pagesDir/${pageTwoId}.html`);
        return fileContent;
    }).catch((error) => {
        console.error(`Cant read file: pagesDir/${pageTwoId}.html`, error)
        throw new Error(`Cant read page: ${pageTwoId}`);
    });

    return (await fileOnePromise) === (await fileTwoPromise);
};

// logger
const writeLog = ({message, data}) => (
    console.log(message, data)
);

const writeError = ({message, error}) => (
    console.log(message, error)
);

// array helpers
const isAllInArrayAreEqual = (arr) => (
    arr.every((element) => element === arr[0])
);

// file service
const DEFAULT_FILE_PARAMS = {encoding: 'utf8'};

const createFilePath = ({directory, fileName}) => (
    `${directory}/${fileName}`
);

const readFileContent = async (filePath) => (
    await fsPromises.readFile(
        filePath,
        DEFAULT_FILE_PARAMS
    )
);

// pages service
const PAGES_DIRECTORY = 'pageDir';
const PAGES_FILE_FORMAT = 'html';

const createPageFilePath = (pageId) => (
    createFilePath({
        directory: PAGES_DIRECTORY,
        fileName: `${pageId}.${PAGES_FILE_FORMAT}`
    })
);

// compareTwoPages resolver
const handlePageReadError = ({filePath, error}) => {
    writeError({message: `Cant read file: pagesDir/${filePath}.html`, error})
    throw new Error(`Cant read page: ${filePath}`);
};

const readPageContent = (pageId) => {
    const filePath = createPageFilePath(pageId);

    writeLog(`File read: ${filePath}`);

    return readFileContent(filePath).catch((error) => {
        handlePageReadError({filePath, error});
    });
};

const compareTwoPages = async ({pageOneId, pageTwoId}) => {
    const pagesArray = [pageOneId, pageTwoId];

    writeLog({message: `Start read pages: ${pagesArray.join('; ')}`});

    return await isAllInArrayAreEqual(
        await Promise.all(
            pagesArray.map(readPageContent)
        )
    );
}