import { type PermissionBaseline, parseModuleManifest } from "@ekklesia/contracts";
import { describe, expect, it } from "vitest";
import {
  CORE_AUTHORIZATION_GRANTS_MANAGE,
  CORE_MODULES_UI_READ,
  CORE_PERMISSION_DECLARATIONS,
  PermissionRegistryError,
} from "../src/authorization/index.js";
import type { DiscoveredModule } from "../src/modules/discovery.js";
import {
  composePlatformPermissionRegistry,
  ModulePermissionCompositionError,
} from "../src/modules/permissions.js";

interface PermissionInput {
  readonly id: string;
  readonly baseline: PermissionBaseline;
  readonly description: string;
}

/** A minimal, in-memory `DiscoveredModule` double — no filesystem, no real discovery. The manifest
 * is still built through `parseModuleManifest`, so a fixture that would not actually pass manifest
 * validation cannot silently misrepresent what real discovery would ever produce. Only `manifest`
 * is read by `composePlatformPermissionRegistry`; the rest exist only to satisfy the type. */
function fakeModule(id: string, permissions: readonly PermissionInput[] = []): DiscoveredModule {
  const manifest = parseModuleManifest({
    manifestVersion: 4,
    id,
    name: `${id} module`,
    version: "0.1.0",
    compatibility: { platform: "^0.1.0", moduleSdk: "^0.1.0" },
    permissions,
    entrypoints: {
      // Deliberately a path nothing will ever resolve, proving composition never imports or
      // otherwise touches a module's server entrypoint.
      server: "./dist/does-not-exist/index.js",
    },
  });
  return {
    directory: `/modules/${id}`,
    entrypoints: { server: `/modules/${id}/dist/does-not-exist/index.js` },
    manifest,
    manifestPath: `/modules/${id}/ekklesia.module.json`,
    packageName: `@test/${id}`,
  };
}

describe("composePlatformPermissionRegistry", () => {
  it("composes a Core-only registry when no modules are supplied", () => {
    const registry = composePlatformPermissionRegistry([]);

    expect(registry.declarations).toEqual(CORE_PERMISSION_DECLARATIONS);
    expect(registry.has(CORE_AUTHORIZATION_GRANTS_MANAGE)).toBe(true);
  });

  it("composes Core and multiple discovered modules' declarations into one registry", () => {
    const calendar = fakeModule("calendar", [
      { id: "calendar.events.read", baseline: "restricted", description: "Read events." },
    ]);
    const people = fakeModule("people", [
      { id: "people.directory.read", baseline: "authenticated", description: "Read directory." },
    ]);

    const registry = composePlatformPermissionRegistry([calendar, people]);

    expect(registry.has(CORE_AUTHORIZATION_GRANTS_MANAGE)).toBe(true);
    expect(registry.has(CORE_MODULES_UI_READ)).toBe(true);
    expect(registry.has("calendar.events.read")).toBe(true);
    expect(registry.has("people.directory.read")).toBe(true);
    // Core's own two declarations plus one from each module.
    expect(registry.declarations).toHaveLength(4);
  });

  it("preserves deterministic order: Core first, then modules in the supplied order, then declarations in manifest order", () => {
    const calendar = fakeModule("calendar", [
      { id: "calendar.events.read", baseline: "restricted", description: "Read events." },
      { id: "calendar.events.write", baseline: "restricted", description: "Write events." },
    ]);
    const people = fakeModule("people", [
      { id: "people.directory.read", baseline: "authenticated", description: "Read directory." },
    ]);

    const registry = composePlatformPermissionRegistry([calendar, people]);

    expect(registry.declarations.map((declaration) => declaration.id)).toEqual([
      CORE_AUTHORIZATION_GRANTS_MANAGE,
      CORE_MODULES_UI_READ,
      "calendar.events.read",
      "calendar.events.write",
      "people.directory.read",
    ]);
  });

  it.each([
    "public",
    "authenticated",
    "restricted",
  ] as const)("preserves the exact %s baseline and description of a module declaration", (baseline) => {
    const calendar = fakeModule("calendar", [
      { id: "calendar.events.read", baseline, description: "Read calendar events." },
    ]);

    const registry = composePlatformPermissionRegistry([calendar]);

    expect(registry.get("calendar.events.read")).toEqual({
      id: "calendar.events.read",
      baseline,
      description: "Read calendar events.",
    });
  });

  it("still fails closed for a permission no module or Core ever declared", () => {
    const registry = composePlatformPermissionRegistry([]);

    expect(registry.has("calendar.events.read")).toBe(false);
    expect(registry.get("calendar.events.read")).toBeUndefined();
  });

  it("fails composition on an exact duplicate permission id supplied by two module entries", () => {
    // A permission id must start with its own module's id, so a genuine cross-module collision is
    // only reachable if the supplied list itself contains the same module id twice — real
    // discovery already guarantees module-id uniqueness (`MODULE_ID_DUPLICATE`), but composition
    // re-derives duplicate detection from the flat declaration list regardless, rather than
    // trusting that upstream guarantee alone.
    const first = fakeModule("calendar", [
      { id: "calendar.events.read", baseline: "restricted", description: "Read events." },
    ]);
    const second = fakeModule("calendar", [
      { id: "calendar.events.read", baseline: "public", description: "Also read events." },
    ]);

    expect(() => composePlatformPermissionRegistry([first, second])).toThrow(
      PermissionRegistryError,
    );
  });

  it("rejects a module contributing a permission in the reserved core.* namespace, without leaking a module path", () => {
    // Only a module whose own id is literally "core" can produce a "core."-prefixed permission
    // that still passes the manifest's own module-namespace check — this proves composition
    // catches that case rather than trusting the manifest's self-consistency alone.
    const impostor = fakeModule("core", [
      { id: "core.rogue.permission", baseline: "restricted", description: "Not really Core's." },
    ]);

    let captured: unknown;
    try {
      composePlatformPermissionRegistry([impostor]);
    } catch (error) {
      captured = error;
    }

    expect(captured).toBeInstanceOf(ModulePermissionCompositionError);
    expect(captured).toMatchObject({
      code: "MODULE_PERMISSION_RESERVED_NAMESPACE",
      moduleId: "core",
      permissionId: "core.rogue.permission",
    });
    const publicText = String(captured);
    expect(publicText).not.toContain("/modules/core");
    expect(publicText).not.toContain("ekklesia.module.json");
  });

  it("rejects a reserved-namespace collision even when it would not otherwise duplicate an existing id", () => {
    const impostor = fakeModule("core", [
      {
        id: "core.authorization.grants.manage",
        baseline: "restricted",
        description: "Attempting to shadow Core's own permission.",
      },
    ]);

    expect(() => composePlatformPermissionRegistry([impostor])).toThrow(
      ModulePermissionCompositionError,
    );
  });

  it("removes a module's permissions from the resulting registry once that module is absent from the supplied list", () => {
    const calendar = fakeModule("calendar", [
      { id: "calendar.events.read", baseline: "restricted", description: "Read events." },
    ]);

    const withCalendar = composePlatformPermissionRegistry([calendar]);
    expect(withCalendar.has("calendar.events.read")).toBe(true);

    const withoutCalendar = composePlatformPermissionRegistry([]);
    expect(withoutCalendar.has("calendar.events.read")).toBe(false);
  });

  it("performs no I/O: composition is synchronous and never imports a module's entrypoint", () => {
    const calendar = fakeModule("calendar", [
      { id: "calendar.events.read", baseline: "restricted", description: "Read events." },
    ]);

    // A synchronous return (not a Promise) from a fixture whose entrypoint deliberately resolves
    // to nothing on disk is direct evidence no filesystem or module-code operation occurred.
    const result = composePlatformPermissionRegistry([calendar]);
    expect(result).not.toBeInstanceOf(Promise);
    expect(result.has("calendar.events.read")).toBe(true);
  });

  it("does not mutate the supplied module list or Core's own declaration list", () => {
    const calendar = fakeModule("calendar", [
      { id: "calendar.events.read", baseline: "restricted", description: "Read events." },
    ]);
    const modules = Object.freeze([calendar]);
    const coreDeclarationsBefore = [...CORE_PERMISSION_DECLARATIONS];

    composePlatformPermissionRegistry(modules);

    expect(modules).toEqual([calendar]);
    expect(CORE_PERMISSION_DECLARATIONS).toEqual(coreDeclarationsBefore);
  });

  it("returns a registry and declarations that remain immutable, including module-contributed ones", () => {
    const calendar = fakeModule("calendar", [
      { id: "calendar.events.read", baseline: "restricted", description: "Read events." },
    ]);

    const registry = composePlatformPermissionRegistry([calendar]);

    expect(Object.isFrozen(registry)).toBe(true);
    expect(Object.isFrozen(registry.declarations)).toBe(true);
    for (const declaration of registry.declarations) {
      expect(Object.isFrozen(declaration)).toBe(true);
    }
  });
});