import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
import type { AgentConfigInfo, AgentEvent, AgentInfo } from "./agents";
import { agentsApi, subscribeAgentStream } from "./agents";
import { installRpcMock } from "./__test_utils__/mockRpcWebSocket";

beforeEach(() => {
	vi.stubGlobal("fetch", vi.fn());
});

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

const sampleAgent: AgentInfo = {
	story_id: "42_story_test",
	agent_name: "coder",
	status: "running",
	session_id: null,
	worktree_path: null,
	base_branch: null,
	log_session_id: null,
};

const sampleConfig: AgentConfigInfo = {
	name: "coder",
	role: "engineer",
	stage: "coder",
	model: "claude-sonnet-4-6",
	allowed_tools: null,
	max_turns: null,
	max_budget_usd: null,
};

// ── agentsApi ────────────────────────────────────────────────────────────────

describe("agentsApi", () => {
	describe("startAgent", () => {
		it("dispatches agents.start RPC with story_id and returns AgentInfo", async () => {
			const rpc = installRpcMock();
			rpc.respond("agents.start", sampleAgent);

			const result = await agentsApi.startAgent("42_story_test");

			expect(rpc.calls).toEqual([
				{
					method: "agents.start",
					params: { story_id: "42_story_test", agent_name: undefined },
				},
			]);
			expect(result).toEqual(sampleAgent);
		});

		it("sends optional agent_name in params", async () => {
			const rpc = installRpcMock();
			rpc.respond("agents.start", sampleAgent);

			await agentsApi.startAgent("42_story_test", "coder");

			expect(rpc.calls).toEqual([
				{
					method: "agents.start",
					params: { story_id: "42_story_test", agent_name: "coder" },
				},
			]);
		});
	});

	describe("stopAgent", () => {
		it("dispatches agents.stop RPC with story_id and agent_name", async () => {
			const rpc = installRpcMock();
			rpc.respond("agents.stop", true);

			const result = await agentsApi.stopAgent("42_story_test", "coder");

			expect(rpc.calls).toEqual([
				{
					method: "agents.stop",
					params: { story_id: "42_story_test", agent_name: "coder" },
				},
			]);
			expect(result).toBe(true);
		});
	});

	describe("getAgentConfig", () => {
		it("dispatches an agent_config.list RPC and returns the config list", async () => {
			const rpc = installRpcMock();
			rpc.respond("agent_config.list", [sampleConfig]);

			const result = await agentsApi.getAgentConfig();

			expect(rpc.calls).toEqual([
				{ method: "agent_config.list", params: {} },
			]);
			expect(result).toEqual([sampleConfig]);
		});

		it("surfaces RPC errors visibly", async () => {
			const rpc = installRpcMock();
			rpc.respondError("agent_config.list", "config not found", "NOT_FOUND");

			await expect(agentsApi.getAgentConfig()).rejects.toThrow(
				"config not found",
			);
		});
	});

	describe("reloadConfig", () => {
		it("dispatches agent_config.list RPC and returns the config list", async () => {
			const rpc = installRpcMock();
			rpc.respond("agent_config.list", [sampleConfig]);

			const result = await agentsApi.reloadConfig();

			expect(rpc.calls).toEqual([
				{ method: "agent_config.list", params: {} },
			]);
			expect(result).toEqual([sampleConfig]);
		});
	});

	describe("error handling", () => {
		it("surfaces RPC errors from startAgent", async () => {
			const rpc = installRpcMock();
			rpc.respondError("agents.start", "story not found", "NOT_FOUND");

			await expect(agentsApi.startAgent("missing_story")).rejects.toThrow(
				"story not found",
			);
		});
	});
});

// ── subscribeAgentStream ─────────────────────────────────────────────────────

interface MockESInstance {
	url: string;
	onmessage: ((e: { data: string }) => void) | null;
	onerror: ((e: Event) => void) | null;
	close: ReturnType<typeof vi.fn>;
	simulateMessage: (data: unknown) => void;
	simulateError: (e: Event) => void;
}

function makeMockEventSource() {
	const instances: MockESInstance[] = [];

	class MockEventSource {
		onmessage: ((e: { data: string }) => void) | null = null;
		onerror: ((e: Event) => void) | null = null;
		close = vi.fn();

		constructor(public url: string) {
			instances.push(this as unknown as MockESInstance);
		}

		simulateMessage(data: unknown) {
			this.onmessage?.({ data: JSON.stringify(data) });
		}

		simulateError(e: Event) {
			this.onerror?.(e);
		}
	}

	return { MockEventSource, instances };
}

describe("subscribeAgentStream", () => {
	let instances: MockESInstance[];

	beforeEach(() => {
		const { MockEventSource, instances: inst } = makeMockEventSource();
		instances = inst;
		vi.stubGlobal("EventSource", MockEventSource);
	});

	it("creates an EventSource with encoded story and agent in URL", () => {
		subscribeAgentStream("42_story_test", "coder", vi.fn());

		expect(instances).toHaveLength(1);
		expect(instances[0].url).toContain(
			`/agents/${encodeURIComponent("42_story_test")}/${encodeURIComponent("coder")}/stream`,
		);
	});

	it("calls onEvent when a message is received", () => {
		const onEvent = vi.fn();
		subscribeAgentStream("42_story_test", "coder", onEvent);

		const event: AgentEvent = { type: "output", text: "hello" };
		instances[0].simulateMessage(event);

		expect(onEvent).toHaveBeenCalledWith(event);
	});

	it("closes EventSource on 'done' type event", () => {
		subscribeAgentStream("42_story_test", "coder", vi.fn());

		instances[0].simulateMessage({ type: "done" });

		expect(instances[0].close).toHaveBeenCalled();
	});

	it("closes EventSource on 'error' type event", () => {
		subscribeAgentStream("42_story_test", "coder", vi.fn());

		instances[0].simulateMessage({
			type: "error",
			message: "something failed",
		});

		expect(instances[0].close).toHaveBeenCalled();
	});

	it("closes EventSource on status=stopped event", () => {
		subscribeAgentStream("42_story_test", "coder", vi.fn());

		instances[0].simulateMessage({ type: "status", status: "stopped" });

		expect(instances[0].close).toHaveBeenCalled();
	});

	it("does not close on status=running event", () => {
		subscribeAgentStream("42_story_test", "coder", vi.fn());

		instances[0].simulateMessage({ type: "status", status: "running" });

		expect(instances[0].close).not.toHaveBeenCalled();
	});

	it("does not close on 'output' event", () => {
		subscribeAgentStream("42_story_test", "coder", vi.fn());

		instances[0].simulateMessage({ type: "output", text: "building..." });

		expect(instances[0].close).not.toHaveBeenCalled();
	});

	it("calls onError and closes on EventSource onerror", () => {
		const onError = vi.fn();
		subscribeAgentStream("42_story_test", "coder", vi.fn(), onError);

		const err = new Event("error");
		instances[0].simulateError(err);

		expect(onError).toHaveBeenCalledWith(err);
		expect(instances[0].close).toHaveBeenCalled();
	});

	it("closes EventSource when onError is not provided", () => {
		subscribeAgentStream("42_story_test", "coder", vi.fn());

		const err = new Event("error");
		instances[0].simulateError(err);

		expect(instances[0].close).toHaveBeenCalled();
	});

	it("closes EventSource when cleanup function is called", () => {
		const cleanup = subscribeAgentStream("42_story_test", "coder", vi.fn());

		cleanup();

		expect(instances[0].close).toHaveBeenCalled();
	});

	it("handles malformed JSON without throwing", () => {
		subscribeAgentStream("42_story_test", "coder", vi.fn());

		expect(() => {
			instances[0].onmessage?.({ data: "{ not valid json" });
		}).not.toThrow();
	});

	it("delivers multiple events before a terminal event", () => {
		const onEvent = vi.fn();
		subscribeAgentStream("42_story_test", "coder", onEvent);

		instances[0].simulateMessage({ type: "output", text: "line 1" });
		instances[0].simulateMessage({ type: "output", text: "line 2" });
		instances[0].simulateMessage({ type: "done" });

		expect(onEvent).toHaveBeenCalledTimes(3);
		expect(instances[0].close).toHaveBeenCalledTimes(1);
	});
});