error_handling.js

import {
    CACHE_ERRORS_SECONDS,
    PLAIN_TEXT_CONTENT_TYPE,
} from './constants'

/**
 * A face will be picked from this list at random. Add and remove faces to suit
 * your needs/preferences.
 *
 * @type {string[]}
 */
const ERROR_FACES = [
    "¯\\_(ツ)_/¯",
    "(⊙_⊙)？",
    "ಥ_ಥ",
    "＼（〇_ｏ）／",
    "¯\\(°_o)/¯",
    "╮（╯＿╰）╭",
    "╮(╯▽╰)╭",
    "(⊙_⊙;)",
    "(°ロ°) !",
    "┐('～`;)┌",
    "┐(￣ヘ￣;)┌",
    "( ಠ ʖ̯ ಠ)",
    "ლ(ಠ_ಠ ლ)",
    `ლ(¯ロ¯"ლ)`,
    "┐(￣ヮ￣)┌",
    "(눈_눈)",
    "(ﾉ◕ヮ◕)ﾉ*:･ﾟ✧",
    "(ಠ_ಠ)",
    "(￣﹃￣)",
    "(ʘ ͟ʖ ʘ)",
    "( ಥ ʖ̯ ಥ)",
    "( ͡° ʖ̯ ͡°)",
]


/**
 * A map of response codes to what they mean so we can display some descriptive
 * text instead of just a goofy random face when a problem occurs.
 */
const ERROR_CODES = {
    "400": "Bad Request",
    "401": "Unauthorized",
    "402": "Payment Required",
    "403": "Forbidden",
    "404": "Not Found",
    "405": "Method Not Allowed",
    "406": "Not Acceptable",
    "407": "Proxy Authentication Required",
    "408": "Request Timeout",
    "409": "Conflict",
    "410": "Gone",
    "411": "Length Required",
    "412": "Precondition Required",
    "413": "Request Entry Too Large",
    "414": "Request-URI Too Long",
    "415": "Unsupported Media Type",
    "416": "Requested Range Not Satisfiable",
    "417": "Expectation Failed",
    "500": "Internal Server Error",
    "501": "Not Implemented",
    "502": "Bad Gateway",
    "503": "Service Unavailable",
    "504": "Gateway Timeout",
    "505": "HTTP Version Not Supported",
}

export function getFacesPage() {
    return new Response(`${ERROR_FACES.join(" \n")}`, {
        headers: {"Content-Type": PLAIN_TEXT_CONTENT_TYPE}
    })
}


/**
 * Rewrite error responses from Backblaze B2 to have fun little faces. This
 * obfuscates the fact that Backblaze B2 is being used and is generally a
 * more succinct error page for end users.
 *
 * @param {Request} request the request from the client to B2
 * @param {Response} response the response from B2 to copy and modify
 * @returns {Promise<Response>} the new response with a face and description
 */
export async function rewriteErrorResponse(request, response) {
    console.log("rewriteErrorResponse...")
    console.log("Original error response:")
    console.log(response)

    // pick a random face from our ERROR_FACES array
    const randomIdx = Math.floor(Math.random() * ERROR_FACES.length)
    const randomFace = ERROR_FACES[randomIdx]
    const statusText = ERROR_CODES[response.status]
    let responseBody = `${statusText}\n${randomFace}`

    return new Response(responseBody, {
        status: response.status,
        statusText: statusText,
        headers: {
            "Cache-Control": `public, immutable, max-age=${CACHE_ERRORS_SECONDS}`,
            "Content-Type": PLAIN_TEXT_CONTENT_TYPE,
        }
    })
}

export default rewriteErrorResponse