import { load } from "cheerio"
import { DSVRowArray, csvFormatRow, csvParse } from "d3-dsv"

/**
 * Returns the data from an HTML table as an array of objects.
 *
 * @param url The URL of the page containing the HTML table.
 * @param options Optional parameters to specify the table selector and index.
 * @param options.selector A CSS selector to identify the table.
 * @param options.index The index of the table if multiple tables match the selector.
 *
 * @example
 * Basic usage
 * ```js
 * // This would parse the data from the fourth
 * // table with the class name data-table.
 * const data = await getHtmlTable("your-url-here", {
 *   selector: ".data-table",
 *   index: 3
 * })
 * ```
 *
 * @category Web scraping
 */

export default async function getHtmlTable(
    url: string,
    options: {
        selector?: string
        index?: number
    } = {}
): Promise<DSVRowArray<string>> {
    const response = await fetch(url)
    const html = await response.text()

    const $ = load(html)

    let table
    if (typeof options.selector === "string") {
        table = $(options.selector).filter(
            (i) => i === (typeof options.index === "number" ? options.index : 0)
        )
    } else {
        table = $("table").filter(
            (i) => i === (typeof options.index === "number" ? options.index : 0)
        )
    }

    let csv = ""
    table.find("tr").each((i, tr) => {
        const row: string[] = []

        $(tr)
            .find("th, td")
            .each((j, th) => {
                row.push($(th).text().trim())
            })

        csv += `${csvFormatRow(row)}\n`
    })

    const data = csvParse(csv)
    delete data["columns" as unknown as number]

    return data
}