import type { ModuleSecretSource } from "@ekklesia/contracts";
import type { DatabaseTransportPolicyInput } from "../database/index.js";
import type { ClientAddressConfigInput } from "../identity/index.js";
import type { MailProviderConfigInput } from "../mail/index.js";
import { createEnvironmentModuleSecretSource } from "../modules/index.js";
import type { StorageProviderConfigInput } from "../storage/index.js";

/**
 * A deployment's environment, passed **as an argument**.
 *
 * `process.env` satisfies this, but nothing here reads it: the repository rule that only
 * executables touch the process environment is preserved exactly as
 * `createEnvironmentModuleSecretSource` preserves it, and it is what makes every variable this
 * module understands testable without mutating global state.
 */
export type HostEnvironment = Readonly<Record<string, string | undefined>>;

export type HostEnvironmentName = "development" | "production";

/**
 * The identity settings as they appear in the environment — strings, unvalidated.
 *
 * Typed as `string | undefined` rather than `unknown` so this one object can be handed to both
 * `createIdentityConfig` (which validates it) and Doctor's `identityConfiguration` (which validates
 * it and reports the sanitized code) without either side re-deriving it.
 */
export interface HostIdentityEnvironmentInput {
  readonly baseUrl: string | undefined;
  /** Where an emailed verification or reset link sends a browser. Unset means the Dashboard is
   * served from `baseUrl`, which is the ordinary same-origin production shape (ADR 0038). */
  readonly dashboardOrigin: string | undefined;
  readonly publicSignupEnabled: string | undefined;
  readonly secret: string | undefined;
  readonly trustedOrigins: readonly string[] | undefined;
}

/**
 * Every host infrastructure input an Ekklesia executable resolves from its environment.
 *
 * Deliberately **unvalidated**: each consumer runs the same Core validator over these values, but
 * they do so at different moments and want different failure behaviour. `startApi` wants a
 * malformed value to abort startup; Doctor wants it reported as a sanitized code in a check. If this
 * type were pre-validated, Doctor could never report a configuration error — the load would have
 * thrown before a report existed.
 *
 * The API listener's own `host`/`port` are deliberately absent: they describe the API process, not
 * the host infrastructure a diagnostic evaluates, and Doctor has no use for them.
 */
export interface HostConfiguration {
  /** `"development"` only when `NODE_ENV` is exactly that string, so an unset or misspelled value
   * validates as production and never silently relaxes a security rule. */
  readonly environment: HostEnvironmentName;
  /** `undefined` when no mode is set at all, which selects direct mode. */
  readonly clientAddress: ClientAddressConfigInput | undefined;
  readonly databaseTransport: DatabaseTransportPolicyInput;
  readonly databaseUrl: string | undefined;
  readonly identity: HostIdentityEnvironmentInput;
  readonly mail: MailProviderConfigInput;
  /** The deployment's module secrets, resolvable only under names Core derives from a module's own
   * declared keys — there is no arbitrary variable lookup. */
  readonly moduleSecrets: ModuleSecretSource;
  /** `EKKLESIA_MODULES_DIR`, raw and unvalidated: `undefined` only when the variable is unset. Every
   * executable passes it to `resolveModulesDirectory`, the one place it is interpreted (ADR 0048),
   * so a relative or blank value is refused there rather than repaired here. */
  readonly modulesDirectory: string | undefined;
  readonly storage: StorageProviderConfigInput;
}

function splitList(value: string | undefined): readonly string[] | undefined {
  if (value === undefined) {
    return undefined;
  }
  return value
    .split(",")
    .map((entry) => entry.trim())
    .filter((entry) => entry.length > 0);
}

/** Omitted entirely when no mode is set: reading `header`/`trustedProxies` only when `mode` is
 * actually present keeps an operator from half-configuring proxy mode by setting one of three
 * variables. */
function readClientAddress(environment: HostEnvironment): ClientAddressConfigInput | undefined {
  const mode = environment.EKKLESIA_CLIENT_ADDRESS_MODE;
  if (mode === undefined) {
    return undefined;
  }
  return {
    header: environment.EKKLESIA_CLIENT_ADDRESS_HEADER,
    mode,
    trustedProxies: splitList(environment.EKKLESIA_CLIENT_ADDRESS_TRUSTED_PROXIES),
  };
}

/**
 * The one place any Ekklesia executable turns a deployment environment into host infrastructure
 * configuration.
 *
 * It exists because the alternative was demonstrably wrong: `apps/api` and `pnpm doctor` each read
 * their own subset of the same variables, and the subsets drifted. Doctor never read `S3_*` at all,
 * so a correctly configured installation was told its object storage was "not configured" and every
 * module requiring a bucket was reported blocked — while `startApi`, from the identical environment,
 * bound those buckets and ran the modules. A diagnostic that disagrees with the runtime it
 * diagnoses is worse than no diagnostic.
 *
 * So there is now exactly one mapping from variable names to typed inputs, and both executables call
 * it. Validation stays where it already lives — `createIdentityConfig`,
 * `createDatabaseTransportPolicy`, `createStorageProviderConfig`, `createMailProviderConfig` — and
 * is deliberately *not* performed here, so each caller keeps its own failure behaviour.
 *
 * Nothing is read from `process.env`, and nothing here logs, prints, or serializes: the returned
 * object carries the identity secret, both storage credentials, and the SMTP password.
 */
export function loadHostConfiguration(environment: HostEnvironment): HostConfiguration {
  return Object.freeze({
    clientAddress: readClientAddress(environment),
    databaseTransport: {
      ...(environment.EKKLESIA_DATABASE_CA === undefined
        ? {}
        : { certificateAuthority: environment.EKKLESIA_DATABASE_CA }),
      ...(environment.EKKLESIA_DATABASE_TLS_MODE === undefined
        ? {}
        : { mode: environment.EKKLESIA_DATABASE_TLS_MODE }),
    },
    databaseUrl: environment.DATABASE_URL,
    environment: environment.NODE_ENV === "development" ? "development" : "production",
    identity: {
      baseUrl: environment.EKKLESIA_IDENTITY_BASE_URL,
      dashboardOrigin: environment.EKKLESIA_DASHBOARD_ORIGIN,
      publicSignupEnabled: environment.EKKLESIA_PUBLIC_SIGNUP_ENABLED,
      secret: environment.EKKLESIA_IDENTITY_SECRET,
      trustedOrigins: splitList(environment.EKKLESIA_IDENTITY_TRUSTED_ORIGINS),
    },
    // Names follow the platform's own `EKKLESIA_<DOMAIN>_<FIELD>` convention rather than a
    // provider's. Absent host means this installation sends no outbound email, which is a complete
    // deployment (ADR 0037); username and password are optional as a pair, because a relay
    // authorized by source IP has neither.
    mail: {
      fromAddress: environment.EKKLESIA_SMTP_FROM_ADDRESS,
      fromName: environment.EKKLESIA_SMTP_FROM_NAME,
      // The name this client announces in `EHLO`. Optional, and unset is the ordinary case: it
      // matters only where the machine's own hostname is not a fully qualified name the relay will
      // accept.
      heloName: environment.EKKLESIA_SMTP_HELO_NAME,
      host: environment.EKKLESIA_SMTP_HOST,
      password: environment.EKKLESIA_SMTP_PASSWORD,
      port: environment.EKKLESIA_SMTP_PORT,
      security: environment.EKKLESIA_SMTP_SECURITY,
      username: environment.EKKLESIA_SMTP_USERNAME,
    },
    moduleSecrets: createEnvironmentModuleSecretSource(environment),
    modulesDirectory: environment.EKKLESIA_MODULES_DIR,
    // The `S3_*` names ADR 0004 already established for this repository's Compose stack. Absent
    // endpoint means this installation has no object storage, which is a complete deployment
    // (ADR 0030).
    storage: {
      accessKey: environment.S3_ACCESS_KEY,
      bucketPrefix: environment.S3_BUCKET_PREFIX,
      // Optional, and unset is the ordinary case: it matters only where the name Core reaches
      // storage by is not a name a browser could resolve.
      deliveryEndpoint: environment.S3_DELIVERY_ENDPOINT,
      endpoint: environment.S3_ENDPOINT,
      forcePathStyle: environment.S3_FORCE_PATH_STYLE,
      region: environment.S3_REGION,
      secretKey: environment.S3_SECRET_KEY,
    },
  });
}