import { mkdirSync } from "node:fs";
import { dirname, resolve } from "node:path";

export type AppConfig = {
  nodeEnv: string;
  host: string;
  port: number;
  databasePath: string;
  storageDir: string;
  jwtSecret: string;
  cookieName: string;
  cookieSecure: boolean;
  openLibraryEnabled: boolean;
  libraryPathAliases: Array<{ from: string; to: string }>;
  initialAdminEmail: string;
  initialAdminPassword: string;
  initialAdminPasswordIsDefault: boolean;
};

const DEFAULT_INITIAL_ADMIN_EMAIL = "admin@readabook.local";
const DEFAULT_INITIAL_ADMIN_PASSWORD = "readabook-admin-change-me";

export function loadConfig(): AppConfig {
  const databasePath = resolve(process.env.DATABASE_PATH ?? "./data/readabook.sqlite");
  const storageDir = resolve(process.env.STORAGE_DIR ?? "./data/storage");

  mkdirSync(dirname(databasePath), { recursive: true });
  mkdirSync(storageDir, { recursive: true });

  return {
    nodeEnv: process.env.NODE_ENV ?? "development",
    host: process.env.HOST ?? "0.0.0.0",
    port: Number(process.env.PORT ?? 3000),
    databasePath,
    storageDir,
    jwtSecret: process.env.JWT_SECRET ?? "dev-change-me-readabook",
    cookieName: process.env.AUTH_COOKIE_NAME ?? "readabook_session",
    cookieSecure: process.env.COOKIE_SECURE === "true",
    openLibraryEnabled: process.env.OPEN_LIBRARY_ENABLED !== "false",
    libraryPathAliases: parseLibraryPathAliases(process.env.LIBRARY_PATH_ALIASES),
    initialAdminEmail: process.env.INITIAL_ADMIN_EMAIL ?? DEFAULT_INITIAL_ADMIN_EMAIL,
    initialAdminPassword: process.env.INITIAL_ADMIN_PASSWORD ?? DEFAULT_INITIAL_ADMIN_PASSWORD,
    initialAdminPasswordIsDefault: !process.env.INITIAL_ADMIN_PASSWORD
  };
}

function parseLibraryPathAliases(value: string | undefined): Array<{ from: string; to: string }> {
  if (!value) return [];
  return value
    .split(";")
    .map((entry) => entry.trim())
    .filter(Boolean)
    .map((entry) => {
      const separator = entry.indexOf("=");
      if (separator === -1) return null;
      const from = entry.slice(0, separator).trim();
      const to = entry.slice(separator + 1).trim();
      return from && to ? { from, to } : null;
    })
    .filter((entry): entry is { from: string; to: string } => Boolean(entry));
}