/**
 * Verify the documentation example from extensions.md compiles and works.
 */

import { describe, expect, it } from "vitest";
import type {
  ExtensionAPI,
  SessionBeforeCompactEvent,
  SessionCompactEvent,
} from "../src/core/extensions/index.js";

describe("Documentation example", () => {
  it("custom compaction example should type-check correctly", () => {
    // This is the example from extensions.md - verify it compiles
    const exampleExtension = (pi: ExtensionAPI) => {
      pi.on(
        "session_before_compact",
        async (event: SessionBeforeCompactEvent, ctx) => {
          // All these should be accessible on the event
          const { preparation, branchEntries } = event;
          // sessionManager, modelRegistry, and model come from ctx
          const { sessionManager, modelRegistry } = ctx;
          const {
            messagesToSummarize,
            turnPrefixMessages,
            tokensBefore,
            firstKeptEntryId,
            isSplitTurn,
          } = preparation;

          // Verify types
          expect(Array.isArray(messagesToSummarize)).toBe(true);
          expect(Array.isArray(turnPrefixMessages)).toBe(true);
          expect(typeof isSplitTurn).toBe("boolean");
          expect(typeof tokensBefore).toBe("number");
          expect(typeof sessionManager.getEntries).toBe("function");
          expect(typeof modelRegistry.getApiKey).toBe("function");
          expect(typeof firstKeptEntryId).toBe("string");
          expect(Array.isArray(branchEntries)).toBe(true);

          const summary = messagesToSummarize
            .filter((m) => m.role === "user")
            .map(
              (m) =>
                `- ${typeof m.content === "string" ? m.content.slice(0, 100) : "[complex]"}`,
            )
            .join("\n");

          // Extensions return compaction content - SessionManager adds id/parentId
          return {
            compaction: {
              summary: `User requests:\n${summary}`,
              firstKeptEntryId,
              tokensBefore,
            },
          };
        },
      );
    };

    // Just verify the function exists and is callable
    expect(typeof exampleExtension).toBe("function");
  });

  it("compact event should have correct fields", () => {
    const checkCompactEvent = (pi: ExtensionAPI) => {
      pi.on("session_compact", async (event: SessionCompactEvent) => {
        // These should all be accessible
        const entry = event.compactionEntry;
        const fromExtension = event.fromExtension;

        expect(entry.type).toBe("compaction");
        expect(typeof entry.summary).toBe("string");
        expect(typeof entry.tokensBefore).toBe("number");
        expect(typeof fromExtension).toBe("boolean");
      });
    };

    expect(typeof checkCompactEvent).toBe("function");
  });
});
