import { mkdir, open, readFile, rename, rm } from "node:fs/promises";
import { dirname } from "node:path";
import { randomUUID } from "node:crypto";
import { parse } from "csv-parse/sync";
import { stringify } from "csv-stringify/sync";

const legacyColumns = [
    "bookingId",
    "createdAt",
    "packageId",
    "packageName",
    "name",
    "email",
    "emailStatus",
    "idempotencyKey",
    "requestHash",
];

const orderColumns = [...legacyColumns, "bookedPackage"];
const customerColumns = [...orderColumns, "customer", "acceptedTerms"];
const consentColumns = [...customerColumns, "consent"];
const phoneColumns = [...customerColumns, "phone"];
export const columns = [...phoneColumns, "consent"];
const jsonColumns = ["bookedPackage", "customer", "acceptedTerms", "consent"];

// Apostroph-Präfix schützt Tabellenprogramme. Ein vorhandenes Apostroph wird
// ebenfalls maskiert, damit Lesen/Schreiben die Originalwerte exakt erhält.
function protectCell(value) {
    const text = String(value ?? "");
    return /^(?:'|[\t\r\n]|\s*[=+@-])/u.test(text) ? `'${text}` : text;
}

function restoreCell(value) {
    return value.startsWith("'") ? value.slice(1) : value;
}

export function createCsvStorage(filePath) {
    return {
        async readAll() {
            let content;
            try {
                content = await readFile(filePath, "utf8");
            } catch (error) {
                if (error.code === "ENOENT") return [];
                throw error;
            }
            if (!content.trim()) throw new Error("Leere Buchungsdatei");
            return parse(content, {
                bom: true,
                columns(header) {
                    if (
                        header.join(",") !== columns.join(",") &&
                        header.join(",") !== customerColumns.join(",") &&
                        header.join(",") !== phoneColumns.join(",") &&
                        header.join(",") !== consentColumns.join(",") &&
                        header.join(",") !== legacyColumns.join(",") &&
                        header.join(",") !== orderColumns.join(",")
                    ) {
                        throw new Error("Unbekanntes CSV-Format");
                    }
                    return header;
                },
                skip_empty_lines: true,
            }).map((row) =>
                Object.fromEntries(
                    Object.entries(row).map(([key, value]) => [
                        key,
                        jsonColumns.includes(key)
                            ? value
                                ? JSON.parse(restoreCell(value))
                                : null
                            : restoreCell(value),
                    ]),
                ),
            );
        },
        async writeAll(records) {
            await mkdir(dirname(filePath), { recursive: true });
            const temporary = `${filePath}.${randomUUID()}.tmp`;
            const content = stringify(
                records.map((row) =>
                    Object.fromEntries(
                        columns.map((column) => [
                            column,
                            protectCell(
                                jsonColumns.includes(column) &&
                                    row[column] != null
                                    ? JSON.stringify(row[column])
                                    : row[column],
                            ),
                        ]),
                    ),
                ),
                { header: true, columns, record_delimiter: "\r\n" },
            );
            try {
                const handle = await open(temporary, "wx", 0o600);
                try {
                    await handle.writeFile(content, "utf8");
                    await handle.sync();
                } finally {
                    await handle.close();
                }
                // Atomarer Austausch im selben Verzeichnis: keine halben Zeilen.
                await rename(temporary, filePath);
            } finally {
                await rm(temporary, { force: true });
            }
        },
    };
}