import {
  type PermissionDeclaration,
  type PermissionId,
  parsePermissionId,
  safeParsePermissionId,
} from "@ekklesia/contracts";

/**
 * Core's registry consumes the one shared `PermissionDeclaration` shape
 * (`packages/contracts/src/authorization.ts`) rather than declaring its own interface — a module
 * manifest's `permissions` array parses into the exact same type, so a declaration a module ships
 * and a declaration Core registers are provably interchangeable. Re-exported here so existing
 * `@ekklesia/core/authorization` consumers keep importing it from this package.
 */
export type { PermissionDeclaration, PermissionDeclarationInput } from "@ekklesia/contracts";

export interface PermissionRegistry {
  readonly declarations: readonly PermissionDeclaration[];
  /** Returns the declaration for a permission id, or `undefined` for anything malformed or not
   * registered — the two are deliberately indistinguishable to callers, so "unknown permission"
   * and "invalid permission" fail closed the same way. */
  get(permissionId: unknown): PermissionDeclaration | undefined;
  has(permissionId: unknown): boolean;
}

export type PermissionRegistryErrorCode = "PERMISSION_REGISTRY_DUPLICATE_DECLARATION";

/** Thrown only at composition time (registry construction), never per-request. Carries the
 * offending permission id deliberately — this is a startup-time programmer/configuration error
 * message, not a runtime response, and a namespaced permission id is not sensitive. */
export class PermissionRegistryError extends Error {
  readonly code: PermissionRegistryErrorCode;
  readonly permissionId: string;

  constructor(permissionId: string) {
    super(`Permission "${permissionId}" is already registered.`);
    this.name = "PermissionRegistryError";
    this.code = "PERMISSION_REGISTRY_DUPLICATE_DECLARATION";
    this.permissionId = permissionId;
    this.stack = `${this.name}: ${this.message}`;
    Object.freeze(this);
  }
}

/**
 * Builds an immutable permission registry from a fixed list of declarations, rejecting any
 * duplicate permission id outright at composition time. Deliberately the smallest mechanism that
 * distinguishes "registered" from "well-formed": no module discovery, no dynamic registration, no
 * network or filesystem I/O. The module integration layer's composer
 * (`composePlatformPermissionRegistry`, `core/src/modules/permissions.ts`) merges Core's own
 * declarations with every discovered module's into one combined list and calls this same
 * constructor, inheriting duplicate detection for free rather than reimplementing it.
 */
export function createPermissionRegistry(
  declarations: readonly PermissionDeclaration[],
): PermissionRegistry {
  const byId = new Map<PermissionId, PermissionDeclaration>();
  for (const declaration of declarations) {
    if (byId.has(declaration.id)) {
      throw new PermissionRegistryError(declaration.id);
    }
    byId.set(declaration.id, Object.freeze({ ...declaration }));
  }
  const frozenDeclarations = Object.freeze([...byId.values()]);

  return Object.freeze({
    declarations: frozenDeclarations,
    get(permissionId: unknown): PermissionDeclaration | undefined {
      const parsed = safeParsePermissionId(permissionId);
      return parsed.success ? byId.get(parsed.data) : undefined;
    },
    has(permissionId: unknown): boolean {
      const parsed = safeParsePermissionId(permissionId);
      return parsed.success && byId.has(parsed.data);
    },
  });
}

/** Restricted: delegated grant administration is itself a privileged action, never public or
 * merely authenticated. A platform owner always passes the evaluator's existing owner bypass and
 * can delegate this permission to another account deliberately via the explicit-grant API. */
export const CORE_AUTHORIZATION_GRANTS_MANAGE: PermissionId = parsePermissionId(
  "core.authorization.grants.manage",
);

/**
 * Authenticated: any signed-in user of this installation may learn which module UIs the platform is
 * currently hosting, because that is exactly what a browser shell has to render before it can offer
 * anything at all. It is deliberately not `public` — the anonymous artifact route (ADR 0025) is
 * careful never to become an enumeration oracle, and an anonymous inventory would hand over the very
 * listing that route withholds. It is deliberately not `restricted` either: a shell that rendered
 * nothing until an operator granted every user this permission would make the platform unusable for
 * its ordinary users, and the module UIs themselves already gate their own content on their own
 * permissions.
 *
 * Listing a module UI is not permission to use that module. Every module route remains enforced
 * against its own declared permission, unchanged.
 */
export const CORE_MODULES_UI_READ: PermissionId = parsePermissionId("core.modules.ui.read");

/**
 * Restricted: reorganizing the Dashboard is an administrative action, not something every signed-in
 * user may do. It is deliberately a **platform** permission and never a module's own — grouping is
 * Ekklesia's presentation configuration, so no module may gate, grant, or influence it (ADR 0027).
 *
 * Holding it confers no module authority whatsoever. Moving a module into a folder changes a
 * presentation row; it grants nobody access to that module's data, and every module route stays
 * enforced against its own declared permission exactly as before.
 */
export const CORE_DASHBOARD_NAVIGATION_MANAGE: PermissionId = parsePermissionId(
  "core.dashboard.navigation.manage",
);

/**
 * Restricted, and it gates **reading as well as changing**. Deciding which installed modules run is
 * an administrative operation, and the read is not a milder version of it: the lifecycle view is the
 * only place a *disabled* module, a *blocked* module, and the required-dependency edges between them
 * are visible at all. `core.modules.ui.read` deliberately exposes the mountable set to every signed-in
 * user; this exposes the parts of the installation that are deliberately not running, which is not
 * the same audience. A second, weaker read permission over the same resource would be ceremony
 * (ADR 0027's reasoning, applied in the other direction).
 *
 * It is a **platform** permission and never a module's. A module can neither declare it, gate it, nor
 * observe it: whether a module runs is a decision its host makes about it, not a decision it takes
 * part in (ADR 0028). Holding it confers no authority inside any module — every module route stays
 * enforced against that module's own declared permission.
 */
export const CORE_MODULES_LIFECYCLE_MANAGE: PermissionId = parsePermissionId(
  "core.modules.lifecycle.manage",
);

/**
 * Restricted, and deliberately **separate from `core.modules.lifecycle.manage`**. The two authorize
 * genuinely different actions: lifecycle decides *whether a module runs at all*, while this decides
 * *how a running module behaves*. Someone trusted to tune a slideshow's timing need not be trusted
 * to take modules offline, and the reverse is equally true, so folding them into one permission
 * would grant authority nobody asked for in whichever direction it was used (ADR 0029).
 *
 * It gates reading as well as writing, because the read returns the module's declared schema
 * together with every stored value — endpoints, bucket names, and whatever else an operator has
 * configured. That is deployment detail, not something every signed-in user needs.
 *
 * **It never exposes secret material.** A `secret` key's value is deployment-supplied, is never
 * persisted, and is never returned by any route; the API reports only whether one is configured.
 * Holding this permission therefore confers no ability to read a credential — there is no code path
 * that would serve one.
 *
 * Like every other Core permission it is a **platform** permission a module can neither declare,
 * gate, nor observe, and holding it confers no authority inside any module.
 */
export const CORE_MODULES_CONFIGURATION_MANAGE: PermissionId = parsePermissionId(
  "core.modules.configuration.manage",
);

/**
 * Restricted, and deliberately a **platform** permission rather than a module's.
 *
 * A device is an identity the platform issues, so deciding that a screen in the foyer may exist —
 * approving its pairing, seeing what has been paired, and taking it away again — is authority over
 * Ekklesia itself, not over the module whose display happens to be shown. Letting a module declare
 * or gate it would mean whoever administers a slideshow could mint credentials that outlive it.
 *
 * It gates approval, listing, and revocation together. Splitting "see the paired devices" from
 * "revoke one" would be ceremony: the same person is trusted with both, and a reader who cannot act
 * on what they see is not a role anyone has asked for (ADR 0027's reasoning, applied again).
 *
 * Holding it confers **no** authority inside any module and no ability to read a device credential
 * — none is stored in a recoverable form, so there is no code path that could serve one (ADR 0036).
 */
export const CORE_DEVICES_MANAGE: PermissionId = parsePermissionId("core.devices.manage");

/**
 * Core's own declarations, exported in deeply immutable form so a trusted composer (the module
 * integration layer, `core/src/modules/permissions.ts`) can build one combined registry from
 * exactly these plus every discovered module's declarations, in a fixed, deterministic order,
 * without reconstructing or guessing Core's own list. `CORE_PERMISSION_REGISTRY` below remains the
 * registry Core-only code and existing tests use directly.
 */
export const CORE_PERMISSION_DECLARATIONS: readonly PermissionDeclaration[] = Object.freeze([
  Object.freeze({
    baseline: "restricted" as const,
    description: "Create, list, and revoke another user's explicit authorization grants.",
    id: CORE_AUTHORIZATION_GRANTS_MANAGE,
  }),
  Object.freeze({
    baseline: "authenticated" as const,
    description: "List the installed module UIs a browser host may mount.",
    id: CORE_MODULES_UI_READ,
  }),
  Object.freeze({
    baseline: "restricted" as const,
    description: "Organize the Dashboard: create, rename, order, and delete navigation groups.",
    id: CORE_DASHBOARD_NAVIGATION_MANAGE,
  }),
  Object.freeze({
    baseline: "restricted" as const,
    description: "Read and change which installed modules are enabled.",
    id: CORE_MODULES_LIFECYCLE_MANAGE,
  }),
  Object.freeze({
    baseline: "restricted" as const,
    description: "Read and change an installed module's own configuration values.",
    id: CORE_MODULES_CONFIGURATION_MANAGE,
  }),
  Object.freeze({
    baseline: "restricted" as const,
    description: "Approve display device pairing, list paired devices, and revoke a device.",
    id: CORE_DEVICES_MANAGE,
  }),
]);

/**
 * Core's own permission registry, containing exactly the Core-owned permissions declared above.
 * Production `apps/api` does not consult this constant directly: it enforces requests against the
 * composed platform registry (`composePlatformPermissionRegistry`,
 * `core/src/modules/permissions.ts`), which merges these same declarations with every installed
 * module's. `CORE_PERMISSION_REGISTRY` remains for Core-only callers and tests that need Core's
 * permissions in isolation, without composing in any module.
 */
export const CORE_PERMISSION_REGISTRY: PermissionRegistry = createPermissionRegistry(
  CORE_PERMISSION_DECLARATIONS,
);