import type { AuthorizationScope, EkklesiaUserId, PermissionId } from "@ekklesia/contracts";
import {
  createUserActor,
  isAuthenticatedPrincipal,
  safeParseAuthorizationScope,
  safeParseEkklesiaUserId,
  safeParseGrantId,
  safeParsePermissionId,
} from "@ekklesia/contracts";
import {
  type AuthorizationStore,
  AuthorizationStoreError,
  CORE_AUTHORIZATION_GRANTS_MANAGE,
  type GrantRecord,
} from "@ekklesia/core/authorization";
import { Hono } from "hono";
import type { Context } from "hono";
import {
  type AuthorizationMiddlewareOptions,
  getAuthorizedPrincipal,
  requirePermission,
  requireTrustedOrigin,
} from "./authorization-middleware.js";

export interface CreateGrantsRoutesOptions extends AuthorizationMiddlewareOptions {
  readonly store: AuthorizationStore;
  readonly trustedOrigins: ReadonlySet<string>;
}

function sanitizedStoreErrorResponse(c: Context, error: unknown): Response {
  c.header("Cache-Control", "no-store");
  if (error instanceof AuthorizationStoreError) {
    const status = error.code === "AUTHORIZATION_GRANT_NOT_FOUND" ? 404 : 503;
    return c.json({ code: error.code }, status);
  }
  return c.json({ code: "INTERNAL_ERROR" }, 503);
}

interface ParsedCreateGrantBody {
  readonly expiresAt?: Date;
  readonly permission: PermissionId;
  readonly scope?: AuthorizationScope;
  readonly subjectUserId: EkklesiaUserId;
}

const CREATE_GRANT_ALLOWED_KEYS = new Set(["subjectUserId", "permission", "scope", "expiresAt"]);

/**
 * Accepts only `subjectUserId`, `permission`, an optional `scope`, and an optional `expiresAt`.
 * Any other key present — `actor`, `sourceKind`, `sourceRef`, any audit field, `createdAt`,
 * `revokedAt`, a grant id, or anything claiming owner/effective-permission state — makes the
 * whole body invalid rather than being silently dropped, so a caller cannot smuggle
 * server-derived fields through a request that otherwise looks well-formed.
 */
function parseCreateGrantBody(raw: unknown): ParsedCreateGrantBody | undefined {
  if (typeof raw !== "object" || raw === null || Array.isArray(raw)) {
    return undefined;
  }
  const body = raw as Record<string, unknown>;
  if (Object.keys(body).some((key) => !CREATE_GRANT_ALLOWED_KEYS.has(key))) {
    return undefined;
  }

  const subjectUserId = safeParseEkklesiaUserId(body.subjectUserId);
  if (!subjectUserId.success) {
    return undefined;
  }
  const permission = safeParsePermissionId(body.permission);
  if (!permission.success) {
    return undefined;
  }

  let scope: AuthorizationScope | undefined;
  if (body.scope !== undefined) {
    const parsedScope = safeParseAuthorizationScope(body.scope);
    if (!parsedScope.success) {
      return undefined;
    }
    scope = parsedScope.data;
  }

  let expiresAt: Date | undefined;
  if (body.expiresAt !== undefined) {
    if (typeof body.expiresAt !== "string") {
      return undefined;
    }
    const parsedDate = new Date(body.expiresAt);
    if (Number.isNaN(parsedDate.getTime())) {
      return undefined;
    }
    expiresAt = parsedDate;
  }

  return Object.freeze({
    ...(expiresAt === undefined ? {} : { expiresAt }),
    permission: permission.data,
    ...(scope === undefined ? {} : { scope }),
    subjectUserId: subjectUserId.data,
  });
}

function serializeGrant(grant: GrantRecord) {
  return {
    createdAt: grant.createdAt.toISOString(),
    expiresAt: grant.expiresAt ? grant.expiresAt.toISOString() : null,
    id: grant.id,
    permission: grant.permission,
    revokedAt: grant.revokedAt ? grant.revokedAt.toISOString() : null,
    scope: grant.scope ?? null,
    sourceKind: grant.sourceKind,
    userId: grant.userId,
  };
}

/**
 * The v1 explicit-grant management API: list, create, and revoke *explicit* grants only. Every
 * route requires `core.authorization.grants.manage`; a platform owner passes through the
 * evaluator's existing owner bypass without ever needing an explicit grant of this permission
 * themselves — that bypass is exactly how a platform owner deliberately delegates grant
 * administration to another account by granting them this one permission.
 *
 * Relationship-derived grants are never reachable through this API in either direction: creation
 * always hard-codes `sourceKind: "explicit"` server-side (the request body cannot supply a
 * `sourceKind` at all), and revocation is constrained to `sourceKind: "explicit"`, so attempting
 * to revoke a relationship-derived grant by id behaves exactly like the grant does not exist —
 * those grants remain owned by the module operation that established the relationship.
 */
export function createGrantsRoutes(options: CreateGrantsRoutesOptions): Hono {
  const routes = new Hono();
  const requireManagePermission = requirePermission(options, CORE_AUTHORIZATION_GRANTS_MANAGE);
  const requireOrigin = requireTrustedOrigin(options.trustedOrigins);

  routes.get("/api/v1/grants", requireManagePermission, async (c) => {
    c.header("Cache-Control", "no-store");
    const subjectUserId = safeParseEkklesiaUserId(c.req.query("userId"));
    if (!subjectUserId.success) {
      return c.json({ code: "INVALID_REQUEST" }, 400);
    }
    try {
      const grants = await options.store.listGrantsForUser(subjectUserId.data, {
        sourceKind: "explicit",
      });
      return c.json({ grants: grants.map(serializeGrant) }, 200);
    } catch (error) {
      return sanitizedStoreErrorResponse(c, error);
    }
  });

  routes.post("/api/v1/grants", requireOrigin, requireManagePermission, async (c) => {
    c.header("Cache-Control", "no-store");
    const principal = getAuthorizedPrincipal(c);
    if (!isAuthenticatedPrincipal(principal)) {
      return c.json({ code: "AUTHORIZATION_DENIED" }, 403);
    }

    let rawBody: unknown;
    try {
      rawBody = await c.req.json();
    } catch {
      return c.json({ code: "INVALID_REQUEST" }, 400);
    }
    const parsed = parseCreateGrantBody(rawBody);
    if (!parsed) {
      return c.json({ code: "INVALID_REQUEST" }, 400);
    }

    // A well-formed PermissionId is not necessarily a *registered* one. Only the trusted registry
    // (never the request) decides what may be granted — the same registry `requireManagePermission`
    // already consults for the caller's own `core.authorization.grants.manage` check — so a caller
    // cannot pre-create a dormant grant for an invented identifier that later becomes effective the
    // moment someone registers it. Sanitized identically to any other denial: this must never reveal
    // whether the identifier was malformed (400, above) or simply unregistered (403, here).
    if (!options.registry.has(parsed.permission)) {
      return c.json({ code: "AUTHORIZATION_DENIED" }, 403);
    }

    try {
      const grant = await options.store.createGrant({
        actor: createUserActor(principal.userId),
        ...(parsed.expiresAt === undefined ? {} : { expiresAt: parsed.expiresAt }),
        permission: parsed.permission,
        ...(parsed.scope === undefined ? {} : { scope: parsed.scope }),
        sourceKind: "explicit",
        userId: parsed.subjectUserId,
      });
      return c.json({ grant: serializeGrant(grant) }, 201);
    } catch (error) {
      return sanitizedStoreErrorResponse(c, error);
    }
  });

  routes.post(
    "/api/v1/grants/:grantId/revoke",
    requireOrigin,
    requireManagePermission,
    async (c) => {
      c.header("Cache-Control", "no-store");
      const principal = getAuthorizedPrincipal(c);
      if (!isAuthenticatedPrincipal(principal)) {
        return c.json({ code: "AUTHORIZATION_DENIED" }, 403);
      }

      const grantId = safeParseGrantId(c.req.param("grantId"));
      if (!grantId.success) {
        return c.json({ code: "INVALID_REQUEST" }, 400);
      }

      try {
        await options.store.revokeGrant({
          actor: createUserActor(principal.userId),
          grantId: grantId.data,
          sourceKind: "explicit",
        });
        return c.json({ success: true }, 200);
      } catch (error) {
        return sanitizedStoreErrorResponse(c, error);
      }
    },
  );

  return routes;
}