import {
  CORE_DASHBOARD_NAVIGATION_MANAGE,
  CORE_MODULES_UI_READ,
} from "@ekklesia/core/authorization";
import {
  DASHBOARD_SORT_ORDER_MAX,
  DASHBOARD_SORT_ORDER_MIN,
  type DashboardStore,
  DashboardStoreError,
  isValidDashboardIdentifier,
  normalizeDashboardGroupLabel,
  resolveDashboardNavigation,
} from "@ekklesia/core/dashboard";
import type { ModuleUiPublicationRegistry } from "@ekklesia/core/modules";
import { Hono } from "hono";
import type { Context } from "hono";
import {
  type AuthorizationMiddlewareOptions,
  getAuthorizedPrincipal,
  requirePermission,
  requireTrustedOrigin,
} from "./authorization-middleware.js";
import { CORE_MUTATION_MAX_BODY_BYTES, platformBodyLimit } from "./body-limits.js";
import { describeMountableModules, type HostModuleUiDescriptor } from "./module-ui-inventory.js";

export const DASHBOARD_NAVIGATION_PATH = "/api/v1/dashboard/navigation";
const DASHBOARD_GROUPS_PATH = `${DASHBOARD_NAVIGATION_PATH}/groups`;
const DASHBOARD_PLACEMENTS_PATH = `${DASHBOARD_NAVIGATION_PATH}/placements`;

/**
 * One module as the Dashboard presents it: the module's display name, plus the generic mount
 * descriptor unchanged.
 *
 * The descriptor is **embedded rather than flattened**, and that is the layering made visible.
 * `module` is exactly `HostModuleUiDescriptor` — the host-neutral answer to "what is mountable and
 * how" (ADR 0026) — and `name` is the Dashboard's presentation concern layered on top. A standalone
 * host consumes the inner object and never learns that Ekklesia has folders; Ekklesia's shell
 * consumes the outer one. Neither contract is warped to serve the other, and there is one
 * construction of the descriptor rather than two that could drift.
 */
export interface DashboardNavigationModuleView {
  readonly name: string;
  readonly module: HostModuleUiDescriptor;
}

export interface DashboardNavigationGroupView {
  /** The stable key, unchanged by a rename. Addresses the group in the mutation API; never displayed. */
  readonly id: string;
  readonly label: string;
  readonly order: number;
  readonly modules: readonly DashboardNavigationModuleView[];
}

export interface DashboardNavigationResponse {
  readonly groups: readonly DashboardNavigationGroupView[];
  /** Modules an administrator placed outside every group, and modules never configured at all — a
   * newly installed module most importantly. Never empty merely because nothing has been arranged. */
  readonly ungrouped: readonly DashboardNavigationModuleView[];
}

export interface CreateDashboardRoutesOptions extends AuthorizationMiddlewareOptions {
  /** The same publication registry the artifact route and the generic inventory serve from: the one
   * accepted, mountable module set. Navigation never rescans, never reads a manifest, and never
   * discovers anything of its own. */
  readonly moduleUi: ModuleUiPublicationRegistry;
  readonly store: DashboardStore;
  readonly trustedOrigins: ReadonlySet<string>;
}

function sanitizedFailure(c: Context, status: 400 | 404 | 503, code: string): Response {
  c.header("Cache-Control", "no-store");
  return c.json({ code }, status);
}

/** Maps the store's own sanitized codes onto HTTP without inventing a second vocabulary. A
 * validation failure the route already rejects can still arrive here from a concurrent change, so
 * both paths are handled rather than assumed unreachable. */
function storeFailure(c: Context, error: unknown): Response {
  if (error instanceof DashboardStoreError) {
    if (error.code === "DASHBOARD_GROUP_NOT_FOUND") {
      return sanitizedFailure(c, 404, error.code);
    }
    if (error.code === "DASHBOARD_READ_FAILED" || error.code === "DASHBOARD_WRITE_FAILED") {
      return sanitizedFailure(c, 503, error.code);
    }
    return sanitizedFailure(c, 400, "INVALID_REQUEST");
  }
  return sanitizedFailure(c, 503, "DASHBOARD_WRITE_FAILED");
}

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}

function parsedSortOrder(value: unknown): number | undefined {
  if (
    typeof value !== "number" ||
    !Number.isSafeInteger(value) ||
    value < DASHBOARD_SORT_ORDER_MIN ||
    value > DASHBOARD_SORT_ORDER_MAX
  ) {
    return undefined;
  }
  return value;
}

const GROUP_BODY_KEYS = new Set(["label", "order"]);
const PLACEMENT_BODY_KEYS = new Set(["groupId", "order"]);

/**
 * Structured, closed validation — never a free-form configuration blob. Any key beyond the declared
 * ones makes the whole body invalid rather than being silently dropped, so a caller cannot smuggle a
 * field a future version might interpret, and a typo fails loudly instead of quietly doing nothing.
 */
function parseGroupBody(raw: unknown): { label: string; order: number } | undefined {
  if (!isRecord(raw) || Object.keys(raw).some((key) => !GROUP_BODY_KEYS.has(key))) {
    return undefined;
  }
  const order = parsedSortOrder(raw.order);
  const label = normalizeDashboardGroupLabel(raw.label);
  if (label === undefined || order === undefined) {
    return undefined;
  }
  return { label, order };
}

function parsePlacementBody(raw: unknown): { groupId: string | null; order: number } | undefined {
  if (!isRecord(raw) || Object.keys(raw).some((key) => !PLACEMENT_BODY_KEYS.has(key))) {
    return undefined;
  }
  const order = parsedSortOrder(raw.order);
  const groupId = raw.groupId;
  if (order === undefined || (groupId !== null && !isValidDashboardIdentifier(groupId))) {
    return undefined;
  }
  return { groupId, order };
}

async function readJsonBody(c: Context): Promise<unknown> {
  try {
    return (await c.req.json()) as unknown;
  } catch {
    return undefined;
  }
}

/**
 * The Ekklesia Dashboard's navigation: how this installation presents its mountable modules, and the
 * narrow, structured API for changing that.
 *
 * ## Navigation is layered on the inventory, not merged into it
 *
 * `GET /api/v1/module-ui` (ADR 0026) answers *what may be mounted* and stays host-neutral — a
 * standalone host uses it and never learns Ekklesia has folders. This route answers *how this
 * Dashboard presents those modules*, and embeds each generic descriptor untouched inside a
 * presentation wrapper. Keeping them separate is what stops Dashboard semantics leaking into the
 * portable module-host contract.
 *
 * ## Grouping is presentation, and structurally cannot be anything else
 *
 * The resolved view is computed by `resolveDashboardNavigation`, a pure function of stored
 * configuration and the current module set. It reads no manifest, no dependency, no capability, and
 * no entrypoint, and it produces no relationship between two modules. Modules stay flat (ADR 0021,
 * ADR 0027): two modules in one group are exactly as related as two in different groups, and moving
 * one changes a single presentation row — never its artifact, its API root, its permissions, its
 * dependencies, or when it starts.
 *
 * ## Reading versus organizing
 *
 * Reading requires `core.modules.ui.read`, the same permission the generic inventory requires,
 * because this response *contains* that inventory and serves the same audience: any signed-in user
 * needs it to see anything at all. Organizing requires `core.dashboard.navigation.manage`
 * (restricted) — a platform permission, never a module's — and, like every other Core mutation, an
 * exact trusted `Origin` and a bounded body before authorization work begins.
 *
 * Holding the manage permission grants no module authority. Every module route remains enforced
 * against its own declared permission, and no arrangement of folders changes a single authorization
 * decision.
 */
export function createDashboardRoutes(options: CreateDashboardRoutesOptions): Hono {
  const routes = new Hono();
  const middlewareOptions: AuthorizationMiddlewareOptions = {
    evaluator: options.evaluator,
    registry: options.registry,
    runtime: options.runtime,
  };
  const requireRead = requirePermission(middlewareOptions, CORE_MODULES_UI_READ);
  const requireManage = requirePermission(middlewareOptions, CORE_DASHBOARD_NAVIGATION_MANAGE);
  const requireOrigin = requireTrustedOrigin(options.trustedOrigins);
  const mutationBodyLimit = platformBodyLimit(CORE_MUTATION_MAX_BODY_BYTES);

  routes.get(DASHBOARD_NAVIGATION_PATH, requireRead, async (c) => {
    c.header("Cache-Control", "no-store");
    // Per-principal: the embedded descriptors carry permission hints evaluated for this caller.
    c.header("Vary", "Origin, Cookie");
    const principal = getAuthorizedPrincipal(c);
    try {
      const [configuration, descriptors] = await Promise.all([
        options.store.readConfiguration(),
        describeMountableModules(options.evaluator, principal, options.moduleUi),
      ]);
      const view = resolveDashboardNavigation(
        configuration,
        descriptors.map((entry) => ({ id: entry.descriptor.id, ...entry })),
      );
      const present = (entry: {
        readonly descriptor: HostModuleUiDescriptor;
        readonly name: string;
      }): DashboardNavigationModuleView => ({ module: entry.descriptor, name: entry.name });
      return c.json(
        {
          groups: view.groups.map((group) => ({
            id: group.id,
            label: group.label,
            modules: group.modules.map(present),
            order: group.order,
          })),
          ungrouped: view.ungrouped.map(present),
        } satisfies DashboardNavigationResponse,
        200,
      );
    } catch (error) {
      if (error instanceof DashboardStoreError) {
        return storeFailure(c, error);
      }
      // An authorization-evaluation outage, exactly as the generic inventory reports it: a
      // permission hint that could not be determined is never rendered as "not granted".
      return sanitizedFailure(c, 503, "AUTHORIZATION_EVALUATION_FAILED");
    }
  });

  routes.put(
    `${DASHBOARD_GROUPS_PATH}/:groupId`,
    requireOrigin,
    mutationBodyLimit,
    requireManage,
    async (c) => {
      c.header("Cache-Control", "no-store");
      const groupId = c.req.param("groupId");
      const body = parseGroupBody(await readJsonBody(c));
      if (!body || !isValidDashboardIdentifier(groupId)) {
        return sanitizedFailure(c, 400, "INVALID_REQUEST");
      }
      try {
        // Idempotent by design: creating and renaming are the same operation against a
        // client-chosen, stable id, so a rename can never orphan the placements pointing at it.
        const group = await options.store.upsertGroup({
          id: groupId,
          label: body.label,
          sortOrder: body.order,
        });
        return c.json({ id: group.id, label: group.label, order: group.sortOrder }, 200);
      } catch (error) {
        return storeFailure(c, error);
      }
    },
  );

  routes.delete(`${DASHBOARD_GROUPS_PATH}/:groupId`, requireOrigin, requireManage, async (c) => {
    c.header("Cache-Control", "no-store");
    const groupId = c.req.param("groupId");
    if (!isValidDashboardIdentifier(groupId)) {
      return sanitizedFailure(c, 400, "INVALID_REQUEST");
    }
    try {
      // Modules in the group become ungrouped through the schema's `on delete set null`, so no
      // module is lost and no placement is left pointing at a group that no longer exists.
      await options.store.deleteGroup(groupId);
      return c.body(null, 204);
    } catch (error) {
      return storeFailure(c, error);
    }
  });

  routes.put(
    `${DASHBOARD_PLACEMENTS_PATH}/:moduleId`,
    requireOrigin,
    mutationBodyLimit,
    requireManage,
    async (c) => {
      c.header("Cache-Control", "no-store");
      const moduleId = c.req.param("moduleId");
      const body = parsePlacementBody(await readJsonBody(c));
      if (!body || !isValidDashboardIdentifier(moduleId)) {
        return sanitizedFailure(c, 400, "INVALID_REQUEST");
      }
      try {
        // A placement may be stored for a module that is not installed: that is how uninstalling
        // and reinstalling preserves an arrangement. Nothing renders it until the module is back.
        const placement = await options.store.setPlacement({
          groupId: body.groupId,
          moduleId,
          sortOrder: body.order,
        });
        return c.json(
          {
            groupId: placement.groupId,
            moduleId: placement.moduleId,
            order: placement.sortOrder,
          },
          200,
        );
      } catch (error) {
        return storeFailure(c, error);
      }
    },
  );

  return routes;
}