import AdmZip from "adm-zip"
import { csvParse, DSVRowArray } from "d3-dsv"
import { Buffer } from "node:buffer"

/**
 * Returns the data from a Statistics Canada table as an array of objects. The first parameter is the pid value that can be found in the table url.
 *
 * @example
 * Basic usage
 * ```js
 * const data = await getStatCanTable('98100001')
 * ```
 *
 * @example
 * With options
 * ```js
 * const data = await getStatCanTable('98100001', {
 *   lang: 'fr',
 *   skipFirstCharacter: true,
 *   returnRawCSV: true,
 * })
 * ```
 *
 * @param pid The pid value that can be found in the table URL.
 * @param options Optional settings.
 * @param options.lang Language of the table, either 'en' or 'fr'. Defaults to 'en'.
 * @param options.skipFirstCharacter Whether to skip the first character of the CSV data. Defaults to false.
 * @param options.returnRawCSV Whether to return the raw CSV data as a string. Defaults to false.
 * @param options.debug Whether to enable debug logging. Defaults to false.
 *
 * @category Web scraping
 */

export default async function getStatCanTable(
    pid: string,
    options: {
        lang?: "en" | "fr"
        skipFirstCharacter?: boolean
        returnRawCSV?: boolean
        debug?: boolean
    } = {}
): Promise<string | DSVRowArray<string>> {
    const lang = options.lang ?? "en"

    if (pid.length > 8) {
        options.debug &&
            console.log(
                `pid ${pid} is too long (max 8 characters). Using ${pid.slice(
                    0,
                    8
                )} instead.`
            )
        pid = pid.slice(0, 8)
    }

    const getCSVResponse = await fetch(
        `https://www150.statcan.gc.ca/t1/wds/rest/getFullTableDownloadCSV/${pid}/${lang}`
    )
    const zippedCsvUrl = await getCSVResponse.json()
    options.debug && console.log(`Fetching ${zippedCsvUrl.object}`)

    const response = await fetch(zippedCsvUrl.object)
    const zipBuffer = Buffer.from(await response.arrayBuffer())
    const zip = new AdmZip(zipBuffer)
    const zipEntries = zip.getEntries()
    const csvEntry = zipEntries.find((d) => d.entryName === `${pid}.csv`)
    if (csvEntry === undefined) {
        throw new Error(`No ${pid}.csv in the zipped file.`)
    }
    const csv = csvEntry.getData().toString()

    if (options.returnRawCSV) {
        return csv
    }

    const data = options.skipFirstCharacter
        ? csvParse(csv.slice(1))
        : csvParse(csv)
    delete data["columns" as unknown as number]

    options.debug &&
        console.log("colums:", JSON.stringify(Object.keys(data[0])))

    options.debug && console.table(data)

    return data
}