// mailu's provisioner — the adapter that makes mailu a provider of the mesh `smtp` interface.
// The reconcile loop, the contributions file, and reading the mesh's minted password are the sdk
// harness's; this writes only the per-service half: how mailu creates and removes a consumer's
// sending account (novox/hq ADR 0048/0076, gitea's package-registry provisioner is the sibling).
//
// The `smtp` interface: a consumer authenticates to submission (port 587, STARTTLS) as a real
// mailbox this provisioner creates. The address is `<account>@<domain>`: the local part is the
// consumer's `account` contribution — the name it wants to send as — falling back to the mesh's
// own login for a consumer that named none; the domain is the mail server's, which is this
// module's fact, not the consumer's.
//
// **The password is the mesh's, not the provisioner's (ADR 0048).** The mesh mints it and hands
// it to both ends; mailu sets exactly that password every run — so a rotation takes — and seals
// nothing: the consumer already has its copy through the mesh's own channel.

import { readFileSync } from "node:fs";
import { runProvisioner, type Provision } from "@novox/mesh-sdk/provisioner";
import { MailuClient } from "../client.js";

const mailu = MailuClient.fromEnv();

// The mail server's own domain: the operator's value, from the settings the mesh merges into this
// module's config file (`settings set mailu` with {"domain": …}; novox/hq ADR 0112, ADR 0155). A
// definition names no mesh, so it is never a literal in the manifest — and it used to be, as
// MESH_MAILU_DOMAIN, which is still read for a mesh that has not re-registered the manifest.
function domain(): string {
  const file = process.env.MESH_MAILU_CONFIG_FILE;
  if (file) {
    try {
      const config = JSON.parse(readFileSync(file, "utf8")) as { domain?: unknown };
      if (typeof config.domain === "string" && config.domain.trim() !== "") return config.domain.trim();
    } catch {
      // Unreadable or not JSON: fall through to the environment, and the error below names both.
    }
  }
  const named = (process.env.MESH_MAILU_DOMAIN ?? "").trim();
  if (named === "") {
    throw new Error(
      "no mail domain is set, so a consumer's address cannot be composed — `settings set mailu <file>` " +
        'with {"domain": "<the mail domain>"}',
    );
  }
  return named;
}

// The address one consumer sends as. The local part is refused rather than sanitised when it is
// not a plain mailbox name — a rewritten name is an address nobody asked for.
function addressOf(p: { as: string; values?: Readonly<Record<string, unknown>> }): string {
  const contributed = typeof p.values?.["account"] === "string" ? (p.values["account"] as string).trim() : "";
  const local = contributed !== "" ? contributed : p.as;
  if (!/^[a-z0-9][a-z0-9._-]*$/.test(local)) {
    throw new Error(`${JSON.stringify(local)} is not a usable mailbox name`);
  }
  return `${local}@${domain()}`;
}

runProvisioner("smtp", {
  async create(p: Provision): Promise<void> {
    const email = addressOf(p);
    // Create if absent, and set exactly the minted password either way so a rotation takes.
    // Mailu's create refuses a duplicate address, which is the signal to fall through to the
    // password set — the same found-then-apply shape gitea's ensureUser settled on.
    try {
      await mailu.createUser(email, p.password);
    } catch {
      await mailu.applyProvisioned(email, p.password);
    }
  },

  async remove(p: { as: string }): Promise<void> {
    // The withdrawal only knows the mesh login, never the contributed local part — so accounts
    // that contributed one are removed when the address matching the login is absent? No: the
    // harness hands remove only `as`, and an address composed from a contribution cannot be
    // recomputed from it. The account is therefore removed by its login-shaped address when one
    // exists, and left otherwise — a mailbox holding mail is the one thing a background loop
    // must not guess about (this module's own events file says the same). Withdrawal of a
    // named-account consumer is an operator action until the harness carries values here.
    await mailu.deleteUser(`${p.as}@${domain()}`).catch(() => {});
  },
  // Asked every minute by the harness: whether the backend still holds this consumer exactly as
  // the mesh gave it, so a login lost behind the provisioner's back is made again (novox/hq issue 120).
  async holds(p: Provision): Promise<boolean> {
    return mailu.holdsUser(addressOf(p));
  },
});