/**
 * ctx.operations: declaring what a plugin can do, and asking for another
 * plugin's action to run.
 *
 * invoke acts for the current user, so on its own it would let any plugin spend
 * that user's full authority. It needs the capability, the action named in the
 * manifest's invokes list, and the origin always names the calling plugin, set
 * here from the closure rather than from anything the plugin passes.
 */

import type {
  PluginOperations,
  PluginOperationInvokeOptions,
} from "@termix-ssh/plugin-sdk/backend";
import {
  invokeAllowed,
  type OperationAction,
} from "@termix-ssh/plugin-sdk/operations";
import type { PluginManifest } from "./manifest.js";
import { assertCapability, capabilityRefused } from "./permissions.js";
import { getActor, getActorTrail, type ActorOrigin } from "./actor.js";
import type { DisposableBag } from "./disposables.js";
import {
  registerAction,
  revokeAction,
  type OperationHandler,
} from "../operations/registry.js";
import { provideApprovalPolicy } from "../operations/approvals.js";
import {
  emitOperationEvent,
  subscribeOperationEvents,
} from "../operations/events.js";
import {
  drainPlugin,
  OperationError,
  runOperation,
} from "../operations/gate.js";
import { buildCatalog } from "../operations/catalog.js";

interface Deps {
  manifest: PluginManifest;
  bag: DisposableBag;
}

export function createPluginOperations({
  manifest,
  bag,
}: Deps): PluginOperations {
  const pluginId = manifest.id;
  const declared = manifest.capabilities;
  const contribution = manifest.contributes?.operations;
  let drainRegistered = false;

  const declaredAction = (id: string): OperationAction => {
    const action = contribution?.actions?.find((entry) => entry.id === id);
    if (!action) {
      throw new Error(
        `Plugin ${pluginId} cannot register action "${id}": it is not declared in contributes.operations`,
      );
    }
    return action;
  };

  const actingUser = (): string => {
    const userId = getActor();
    if (!userId) {
      throw new Error(
        "ctx.operations needs an acting user: call it inside a request or ctx.asUser",
      );
    }
    return userId;
  };

  return {
    register: (id, handler) => {
      if (!declared.includes("operations:provide")) {
        throw capabilityRefused(pluginId, "operations:provide");
      }
      const registration = registerAction(
        pluginId,
        declaredAction(id),
        handler as OperationHandler,
      );
      bag.add(() => void revokeAction(registration), `action "${id}"`);
      // Added once and after the actions, so disposal, which runs newest
      // first, drains before anything the handlers use is torn down.
      if (!drainRegistered) {
        drainRegistered = true;
        bag.add(() => drainPlugin(pluginId), "operations drain");
      }
    },

    // A plugin's own route running its own action, so a button press lands in
    // the same history. The caller stays the origin, not this plugin.
    run: async (actionId, options = {}) => {
      if (!declared.includes("operations:provide")) {
        throw capabilityRefused(pluginId, "operations:provide");
      }
      declaredAction(actionId);
      const trail = getActorTrail();
      return runOperation({
        actionId,
        hostId: options.hostId,
        resourceKey: options.resourceKey,
        input: options.input,
        dryRun: options.dryRun,
        confirmed: options.confirmed,
        idempotencyKey: options.idempotencyKey,
        batchId: options.batchId,
        userId: actingUser(),
        origin: trail.origin ?? { kind: "plugin", pluginId },
        apiKeyScopes: trail.apiKeyScopes,
        depth: trail.depth,
      });
    },

    invoke: async (actionId, options = {}) => {
      await assertCapability(pluginId, "operations:invoke", declared);
      if (!invokeAllowed(contribution?.invokes, actionId)) {
        throw new OperationError(
          "FORBIDDEN",
          `${pluginId} did not declare that it runs ${actionId}`,
        );
      }
      const trail = getActorTrail();
      const origin: ActorOrigin = {
        kind: "plugin",
        pluginId,
        via: (options as PluginOperationInvokeOptions).via,
      };
      return runOperation({
        actionId,
        hostId: options.hostId,
        resourceKey: options.resourceKey,
        input: options.input,
        dryRun: options.dryRun,
        confirmed: options.confirmed,
        idempotencyKey: options.idempotencyKey,
        batchId: options.batchId,
        userId: actingUser(),
        origin,
        apiKeyScopes: trail.apiKeyScopes,
        depth: trail.depth,
      });
    },

    list: async (options) => {
      await assertCapability(pluginId, "operations:invoke", declared);
      return buildCatalog({
        userId: actingUser(),
        lang: options?.lang,
        surface: options?.surface,
      });
    },

    emit: async (eventId, payload, options) => {
      if (!declared.includes("operations:provide")) {
        throw capabilityRefused(pluginId, "operations:provide");
      }
      const event = contribution?.events?.find((entry) => entry.id === eventId);
      if (!event) {
        throw new Error(
          `Plugin ${pluginId} cannot emit "${eventId}": it is not declared in contributes.operations`,
        );
      }
      await emitOperationEvent({
        eventId,
        pluginId,
        hostId: options?.hostId,
        severity: event.severity,
        payload,
      });
    },

    onEvent: (subscription) => {
      if (!declared.includes("operations:invoke")) {
        throw capabilityRefused(pluginId, "operations:invoke");
      }
      const remove = subscribeOperationEvents(pluginId, subscription);
      bag.add(remove, `events "${subscription.pattern}"`);
      return remove;
    },

    approvals: {
      provide: (provider) => {
        if (!declared.includes("operations:approve")) {
          throw capabilityRefused(pluginId, "operations:approve");
        }
        const remove = provideApprovalPolicy(pluginId, manifest, provider);
        bag.add(remove, "approval rules");
        return remove;
      },
    },
  };
}