import path from "node:path";
import { composeUp } from "./docker";
import { readEnvFile, readEnvValue, upsertEnvValues } from "./env-file";
import type { ResolvedEmailSettings } from "./global-settings";
import { listBusinessStacks, stackDir } from "./stacks";

export interface EmailRolloutResult {
  slug: string;
  ok: boolean;
  error?: string;
}

/**
 * Pushes global email settings into every business's own `.env` (the
 * same surgical, non-destructive `upsertEnvValues` helper
 * provisioning.ts's own updateBusiness already uses for name/domain
 * edits — never a full-file regenerate, so nothing else hand-edited into
 * a business's .env is touched), then force-recreates its container so
 * the change actually takes effect — a container only reads its `.env`
 * at creation (see docker.ts's composeUp), the same reason
 * updateBusiness recreates on a domain change.
 *
 * EMAIL_REPLY_TO is deliberately excluded from the "always overwrite"
 * set: unlike the SMTP transport itself (host/credentials/from-address),
 * a reply-to address is something a business plausibly wants to be its
 * own (e.g. its own support inbox) rather than a platform-wide value.
 * The global setting is only ever applied as a *fallback* — written the
 * first time (a fresh business's .env has it blank), left untouched
 * forever after a business (or a human editing its .env by hand) sets
 * its own. This mirrors updateBusiness()'s own "never clobber anything
 * hand-edited since provisioning" rule.
 *
 * Runs sequentially, not in parallel: this is an infrequent admin action
 * on a single-VPS, modest-business-count deployment, and sequential
 * keeps one slow/failing business from making the Docker daemon/MySQL
 * connection pool contend with N simultaneous `docker compose up`s. A
 * per-business result is returned so a partial failure (one business's
 * container already down, a stack in a broken state, etc.) is visible
 * rather than silently swallowed — the caller can offer a "Reapply"
 * action that just calls this again.
 */
export async function applyEmailSettingsToAllBusinesses(settings: ResolvedEmailSettings): Promise<EmailRolloutResult[]> {
  const businesses = await listBusinessStacks();
  const results: EmailRolloutResult[] = [];

  for (const business of businesses) {
    try {
      const dir = stackDir(business.slug);
      const envPath = path.join(dir, ".env");

      const currentEnv = await readEnvFile(envPath);
      const currentReplyTo = currentEnv ? readEnvValue(currentEnv, "EMAIL_REPLY_TO") : null;
      const businessHasOwnReplyTo = Boolean(currentReplyTo && currentReplyTo.trim());

      await upsertEnvValues(envPath, {
        EMAIL_PROVIDER: "brevo",
        EMAIL_SMTP_HOST: settings.host,
        EMAIL_SMTP_PORT: String(settings.port),
        EMAIL_SMTP_USERNAME: settings.username,
        EMAIL_SMTP_PASSWORD: settings.password,
        EMAIL_SMTP_ENCRYPTION: settings.encryption,
        EMAIL_FROM_ADDRESS: settings.fromAddress,
        EMAIL_FROM_NAME: settings.fromName,
        ...(businessHasOwnReplyTo ? {} : { EMAIL_REPLY_TO: settings.replyTo }),
      });
      await composeUp(dir, { forceRecreate: true });
      results.push({ slug: business.slug, ok: true });
    } catch (error) {
      results.push({ slug: business.slug, ok: false, error: error instanceof Error ? error.message : String(error) });
    }
  }

  return results;
}