import type { MiddlewareHandler } from 'hono';
import { createRouter } from '../../create-router';
import * as errors from '@@/custom-errors';
import { isSuperAdmin } from '../../super-admin';
import { getAllRoleGrants, replaceRoleGrants, USER_ROLES } from 'officerdb';
import type { UserRole } from 'officerdb';
import { CAPABILITIES, GRANTABLE_CAPABILITIES, CAPABILITY_BY_KEY } from '../../capabilities/registry';
import { getEffectiveCapabilities, invalidateRoleGrants } from '../../capabilities/authorize';

// Two audiences, deliberately split.
//
// `/user/capabilities` answers "what may I do" for the caller, and every account may ask. The dock, the
// app registry and the route guards all read it, so it is the frontend's whole view of the permission
// model — and it must never be the frontend's ENFORCEMENT of it. Hiding a dock icon is a courtesy; the
// 403 in origin-validation is the lock.
//
// Everything else here is owner-only and edits the policy itself.

const ownerGate: MiddlewareHandler = async (ctx, next) => {
  if (!(await isSuperAdmin(ctx.get('user')))) throw errors.FORBIDDEN('Capability management is owner-only');
  return next();
};

/** What the caller may reach. Mounted under /api/user, which is a `core` capability, so nobody is 403'd. */
export const selfCapabilitiesRouter = createRouter();

selfCapabilitiesRouter.get('/capabilities', async (ctx) => {
  const userId = ctx.get('user').id as number;
  const { isOwner, grants } = await getEffectiveCapabilities(userId);

  // The owner holds everything, and says so by listing it rather than by a flag the frontend has to
  // remember to special-case. One shape for both audiences means one code path in the UI.
  const held = isOwner
    ? CAPABILITIES.map((c) => ({ key: c.key, level: 'write' as const }))
    : [...grants].map(([key, level]) => ({ key, level }));

  const heldKeys = new Set(held.map((h) => h.key));

  return ctx.json({
    isOwner,
    capabilities: held,
    // Flattened for the dock and the route guard, which care about paths rather than capability keys.
    routes: held.flatMap(({ key }) => CAPABILITY_BY_KEY.get(key)?.routes ?? []),
    // The complement, and the frontend genuinely needs both. "Not in `routes`" cannot distinguish a route
    // this account lacks from a route no capability claims at all — `/`, the settings shell, the sign-in
    // screens — and a guard that cannot tell those apart either blanks the app or guards nothing.
    deniedRoutes: CAPABILITIES.filter((c) => !heldKeys.has(c.key)).flatMap((c) => c.routes ?? []),
  });
});

/** Policy administration. Owner-only, mounted under /api/users. */
export const capabilityAdminRouter = createRouter();

capabilityAdminRouter.get('/capabilities', ownerGate, async (ctx) => {
  return ctx.json({
    // Only the grantable kind is offered. `execution` and `admin` are deliberately not in this list:
    // a UI that shows a checkbox it will refuse to honour is worse than one that never offered it.
    capabilities: GRANTABLE_CAPABILITIES.map((c) => ({
      key: c.key,
      label: c.label,
      description: c.description,
      // What the owner is actually deciding about, shown so the grant is legible rather than a name.
      routes: c.routes ?? [],
      hasPersonalWrites: !!c.personal?.length,
    })),
    // Roles a grant may name. Super Admin is excluded: the owner bypasses this table entirely, and the
    // database refuses a row for that role.
    roles: USER_ROLES.filter((r) => r !== 'Super Admin'),
    grants: await getAllRoleGrants(),
  });
});

capabilityAdminRouter.put('/capabilities/:role', ownerGate, async (ctx) => {
  const role = ctx.req.param('role') as UserRole;
  if (!USER_ROLES.includes(role)) throw errors.BAD_REQUEST(`Unknown role '${role}'`);
  if (role === 'Super Admin') throw errors.BAD_REQUEST('The owner is not governed by grants');

  const body = ctx.get('body') as { grants?: unknown } | undefined;
  const raw = body?.grants;
  if (!Array.isArray(raw)) throw errors.BAD_REQUEST('Expected { grants: [{ capability, level }] }');

  const grants: { capability: string; level: 'read' | 'write' }[] = [];
  for (const entry of raw) {
    const { capability, level } = (entry ?? {}) as { capability?: unknown; level?: unknown };
    if (typeof capability !== 'string') throw errors.BAD_REQUEST('Each grant needs a capability key');
    if (level !== 'read' && level !== 'write') throw errors.BAD_REQUEST(`Bad level for '${capability}'`);

    // The registry is the authority on what a capability key means, which is why the column has no CHECK.
    // This is where that authority is applied — rejecting a name nothing defines, and refusing to store a
    // grant the resolver would drop on read anyway.
    const known = CAPABILITY_BY_KEY.get(capability);
    if (!known) throw errors.BAD_REQUEST(`Unknown capability '${capability}'`);
    if (known.kind !== 'app') {
      throw errors.BAD_REQUEST(
        known.kind === 'execution'
          ? `${known.label} runs as the server owner and can never be granted`
          : `${known.label} is not grantable`,
      );
    }
    grants.push({ capability, level });
  }

  await replaceRoleGrants(role, grants);
  // The cache's entire invalidation contract, discharged here. Adding a second writer means adding a
  // second call to this — see the note on grantCache in capabilities/authorize.ts.
  invalidateRoleGrants(role);

  return ctx.json({ role, grants });
});
