import { afterEach, describe, expect, test, vi } from "vitest";
import {
  resolvePermissionForwardingTargetSessionId,
  SUBAGENT_PARENT_SESSION_ENV_CANDIDATES,
  SUBAGENT_PARENT_SESSION_ENV_KEY,
} from "../src/permission-forwarding";

afterEach(() => {
  vi.unstubAllEnvs();
});

describe("SUBAGENT_PARENT_SESSION_ENV_CANDIDATES", () => {
  test("is an array containing PI_AGENT_ROUTER_PARENT_SESSION_ID", () => {
    expect(Array.isArray(SUBAGENT_PARENT_SESSION_ENV_CANDIDATES)).toBe(true);
    expect(SUBAGENT_PARENT_SESSION_ENV_CANDIDATES).toContain(
      "PI_AGENT_ROUTER_PARENT_SESSION_ID",
    );
  });

  test("contains PI_SUBAGENT_PARENT_SESSION for CLI-based subagent extensions", () => {
    expect(SUBAGENT_PARENT_SESSION_ENV_CANDIDATES).toContain(
      "PI_SUBAGENT_PARENT_SESSION",
    );
  });

  test("deprecated SUBAGENT_PARENT_SESSION_ENV_KEY equals the first candidate", () => {
    expect(SUBAGENT_PARENT_SESSION_ENV_KEY).toBe(
      SUBAGENT_PARENT_SESSION_ENV_CANDIDATES[0],
    );
  });
});

describe("resolvePermissionForwardingTargetSessionId", () => {
  test("hasUI=true returns the current session ID (UI host owns forwarding)", () => {
    expect(
      resolvePermissionForwardingTargetSessionId({
        hasUI: true,
        isSubagent: false,
        currentSessionId: "parent-session-abc",
        env: {},
      }),
    ).toBe("parent-session-abc");
  });

  test("hasUI=true with isSubagent=true still returns current session ID", () => {
    expect(
      resolvePermissionForwardingTargetSessionId({
        hasUI: true,
        isSubagent: true,
        currentSessionId: "session-xyz",
        env: { PI_AGENT_ROUTER_PARENT_SESSION_ID: "other" },
      }),
    ).toBe("session-xyz");
  });

  test("hasUI=false, isSubagent=false returns null", () => {
    expect(
      resolvePermissionForwardingTargetSessionId({
        hasUI: false,
        isSubagent: false,
        currentSessionId: "session-xyz",
        env: { PI_AGENT_ROUTER_PARENT_SESSION_ID: "parent-session-abc" },
      }),
    ).toBeNull();
  });

  test("isSubagent=true, no candidates set returns null", () => {
    expect(
      resolvePermissionForwardingTargetSessionId({
        hasUI: false,
        isSubagent: true,
        currentSessionId: "session-xyz",
        env: {},
      }),
    ).toBeNull();
  });

  test("isSubagent=true, PI_AGENT_ROUTER_PARENT_SESSION_ID set returns its value", () => {
    expect(
      resolvePermissionForwardingTargetSessionId({
        hasUI: false,
        isSubagent: true,
        currentSessionId: "session-xyz",
        env: { PI_AGENT_ROUTER_PARENT_SESSION_ID: "parent-session-abc" },
      }),
    ).toBe("parent-session-abc");
  });

  test("isSubagent=true, PI_SUBAGENT_PARENT_SESSION resolves when PI_AGENT_ROUTER_PARENT_SESSION_ID is absent", () => {
    expect(
      resolvePermissionForwardingTargetSessionId({
        hasUI: false,
        isSubagent: true,
        currentSessionId: "session-xyz",
        env: {
          PI_SUBAGENT_PARENT_SESSION: "parent-from-convention",
        },
      }),
    ).toBe("parent-from-convention");
  });

  test("isSubagent=true, PI_AGENT_ROUTER_PARENT_SESSION_ID takes precedence over PI_SUBAGENT_PARENT_SESSION", () => {
    expect(
      resolvePermissionForwardingTargetSessionId({
        hasUI: false,
        isSubagent: true,
        currentSessionId: "session-xyz",
        env: {
          PI_AGENT_ROUTER_PARENT_SESSION_ID: "parent-from-router",
          PI_SUBAGENT_PARENT_SESSION: "parent-from-convention",
        },
      }),
    ).toBe("parent-from-router");
  });

  test("isSubagent=true, candidate value is empty string returns null", () => {
    expect(
      resolvePermissionForwardingTargetSessionId({
        hasUI: false,
        isSubagent: true,
        currentSessionId: "session-xyz",
        env: { PI_AGENT_ROUTER_PARENT_SESSION_ID: "" },
      }),
    ).toBeNull();
  });

  test("isSubagent=true, candidate value is 'unknown' returns null", () => {
    expect(
      resolvePermissionForwardingTargetSessionId({
        hasUI: false,
        isSubagent: true,
        currentSessionId: "session-xyz",
        env: { PI_AGENT_ROUTER_PARENT_SESSION_ID: "unknown" },
      }),
    ).toBeNull();
  });

  test("env defaults to process.env when omitted", () => {
    vi.stubEnv("PI_AGENT_ROUTER_PARENT_SESSION_ID", "env-session-abc");
    expect(
      resolvePermissionForwardingTargetSessionId({
        hasUI: false,
        isSubagent: true,
      }),
    ).toBe("env-session-abc");
  });
});