import { promises as fs } from "fs";

function* getLinesFromString(source) {
    let lines = String(source || "").matchAll(/^.+$/gm);
    for (const [line] of lines) yield line;
}

function* getCsvValueFromLine(source, separator) {
    const line = String(source || "");
    const sep = String(separator || ";");
    let inString = false;
    let start = 0;
    for (var i = 0; i < line.length; i++) {
        const char = line[i];
        if (i + 1 === line.length) {
            yield line.substring(start, i + 1); // or slice()
        } else if (!inString && char === sep) {
            yield line.substring(start, i); // or slice()
            start = i + 1;
        } else if (char === '"') {
            inString = !inString;
        }
    }
}

function decodeValue(val) {
    return trimChars(val.trim(), "\"").replace(/""/gm, "\"");
}

function trimChars(s, c) {
    if (c === "]") c = "\\]";
    if (c === "^") c = "\\^";
    if (c === "\\") c = "\\\\";
    return s.replace(new RegExp("^[" + c + "]+|[" + c + "]+$", "g"), "");
}

async function main() {
    console.log("running");

    const data = await fs.readFile("input.csv");
    const csv = data.toString();
    for (const line of getLinesFromString(csv)) {
        console.log("======================")
        for (const value of getCsvValueFromLine(line, ",")) {
            console.log("value:", decodeValue(value));
        }
    }

    console.log("finished");
}

main();