import fs from "node:fs";
import process from "node:process";

export function loadEnvFiles(filePaths: string[]): void {
  for (const filePath of filePaths) {
    loadEnvFile(filePath);
  }
}

function loadEnvFile(filePath: string): void {
  if (!fs.existsSync(filePath)) {
    return;
  }

  const rawText = fs.readFileSync(filePath, "utf8");
  const lines = rawText.split(/\r?\n/);

  for (const rawLine of lines) {
    const line = rawLine.trim();

    if (!line || line.startsWith("#")) {
      continue;
    }

    const separatorIndex = line.indexOf("=");
    if (separatorIndex <= 0) {
      continue;
    }

    const key = line.slice(0, separatorIndex).trim();
    if (!key || key in process.env) {
      continue;
    }

    process.env[key] = parseEnvValue(line.slice(separatorIndex + 1));
  }
}

function parseEnvValue(rawValue: string): string {
  const value = String(rawValue || "").trim();

  if (!value) {
    return "";
  }

  const quote = value[0];
  if ((quote === '"' || quote === "'") && value.endsWith(quote)) {
    return value.slice(1, -1);
  }

  return value;
}

export function parseBoolean(rawValue: unknown): boolean | null {
  const normalized = String(rawValue || "")
    .trim()
    .toLowerCase();

  if (!normalized) {
    return null;
  }

  if (["1", "true", "yes", "on"].includes(normalized)) {
    return true;
  }

  if (["0", "false", "no", "off"].includes(normalized)) {
    return false;
  }

  return null;
}

export function parseInteger(rawValue: unknown): number | null {
  const normalized = String(rawValue || "").trim();

  if (!normalized) {
    return null;
  }

  const parsed = Number(normalized);
  return Number.isFinite(parsed) ? parsed : null;
}

export function parseJsonArray<T = unknown>(rawValue: unknown): T[] | null {
  const normalized = String(rawValue || "").trim();

  if (!normalized) {
    return null;
  }

  try {
    const parsed = JSON.parse(normalized);
    return Array.isArray(parsed) ? (parsed as T[]) : null;
  } catch {
    return null;
  }
}

export function parseCommaSeparatedStrings(rawValue: unknown): string[] | null {
  const normalized = String(rawValue || "").trim();

  if (!normalized) {
    return null;
  }

  const items = normalized
    .split(",")
    .map((item) => item.trim())
    .filter((item) => item.length > 0);

  return items.length > 0 ? items : null;
}