import { describe, expect, it } from "bun:test";
import { Agent } from "@oh-my-pi/pi-agent-core";
import { type AssistantMessage, getModel, type ThinkingBudgets, type Usage } from "@oh-my-pi/pi-ai";
import { AssistantMessageEventStream } from "@oh-my-pi/pi-ai/utils/event-stream";

class MockAssistantStream extends AssistantMessageEventStream {}

function createUsage(): Usage {
	return {
		input: 0,
		output: 0,
		cacheRead: 0,
		cacheWrite: 0,
		totalTokens: 0,
		cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
	};
}

function createAssistantMessage(
	content: AssistantMessage["content"],
	stopReason: AssistantMessage["stopReason"] = "stop",
): AssistantMessage {
	return {
		role: "assistant",
		content,
		api: "openai-responses",
		provider: "openai",
		model: "mock",
		usage: createUsage(),
		stopReason,
		timestamp: Date.now(),
	};
}

describe("Agent", () => {
	it("should create an agent instance with default state", () => {
		const agent = new Agent();

		expect(agent.state).toBeDefined();
		expect(agent.state.systemPrompt).toBe("");
		expect(agent.state.model).toBeDefined();
		expect(agent.state.thinkingLevel).toBe("off");
		expect(agent.state.tools).toEqual([]);
		expect(agent.state.messages).toEqual([]);
		expect(agent.state.isStreaming).toBe(false);
		expect(agent.state.streamMessage).toBe(null);
		expect(agent.state.pendingToolCalls).toEqual(new Set());
		expect(agent.state.error).toBeUndefined();
	});

	it("should create an agent instance with custom initial state", () => {
		const customModel = getModel("openai", "gpt-4o-mini");
		const agent = new Agent({
			initialState: {
				systemPrompt: "You are a helpful assistant.",
				model: customModel,
				thinkingLevel: "low",
			},
		});

		expect(agent.state.systemPrompt).toBe("You are a helpful assistant.");
		expect(agent.state.model).toBe(customModel);
		expect(agent.state.thinkingLevel).toBe("low");
	});

	it("should subscribe to events", () => {
		const agent = new Agent();

		let eventCount = 0;
		const unsubscribe = agent.subscribe(_event => {
			eventCount++;
		});

		// No initial event on subscribe
		expect(eventCount).toBe(0);

		// State mutators don't emit events
		agent.setSystemPrompt("Test prompt");
		expect(eventCount).toBe(0);
		expect(agent.state.systemPrompt).toBe("Test prompt");

		// Unsubscribe should work
		unsubscribe();
		agent.setSystemPrompt("Another prompt");
		expect(eventCount).toBe(0); // Should not increase
	});

	it("should update state with mutators", () => {
		const agent = new Agent();

		// Test setSystemPrompt
		agent.setSystemPrompt("Custom prompt");
		expect(agent.state.systemPrompt).toBe("Custom prompt");

		// Test setModel
		const newModel = getModel("google", "gemini-2.5-flash");
		agent.setModel(newModel);
		expect(agent.state.model).toBe(newModel);

		// Test setThinkingLevel
		agent.setThinkingLevel("high");
		expect(agent.state.thinkingLevel).toBe("high");

		// Test setTools
		const tools = [{ name: "test", description: "test tool" } as any];
		agent.setTools(tools);
		expect(agent.state.tools).toBe(tools);

		// Test replaceMessages
		const messages = [{ role: "user" as const, content: "Hello", timestamp: Date.now() }];
		agent.replaceMessages(messages);
		expect(agent.state.messages).toEqual(messages);
		expect(agent.state.messages).not.toBe(messages); // Should be a copy

		// Test appendMessage
		const newMessage = createAssistantMessage([{ type: "text", text: "Hi" }]);
		agent.appendMessage(newMessage);
		expect(agent.state.messages).toHaveLength(2);
		expect(agent.state.messages[1]).toBe(newMessage);

		// Test clearMessages
		agent.clearMessages();
		expect(agent.state.messages).toEqual([]);
	});

	it("should support steering message queueing", async () => {
		const agent = new Agent();

		const message = { role: "user" as const, content: "Queued message", timestamp: Date.now() };
		agent.steer(message);

		// The message is queued but not yet in state.messages
		expect(agent.state.messages).not.toContainEqual(message);
	});

	it("should handle abort controller", () => {
		const agent = new Agent();

		// Should not throw even if nothing is running
		expect(() => agent.abort()).not.toThrow();
	});

	it("forwards sessionId and thinkingBudgets to streamFn options", async () => {
		let receivedSessionId: string | undefined;
		let receivedBudgets: ThinkingBudgets | undefined;

		const agent = new Agent({
			sessionId: "session-abc",
			thinkingBudgets: { minimal: 64, low: 256 },
			streamFn: (_model, _context, options) => {
				receivedSessionId = options?.sessionId;
				receivedBudgets = options?.thinkingBudgets;
				const stream = new MockAssistantStream();
				queueMicrotask(() => {
					const message = createAssistantMessage([{ type: "text", text: "ok" }]);
					stream.push({ type: "done", reason: "stop", message });
				});
				return stream;
			},
		});

		await agent.prompt("hello");
		expect(receivedSessionId).toBe("session-abc");
		expect(receivedBudgets).toEqual({ minimal: 64, low: 256 });

		agent.sessionId = "session-def";
		agent.thinkingBudgets = { medium: 512 };

		await agent.prompt("hello again");
		expect(receivedSessionId).toBe("session-def");
		expect(receivedBudgets).toEqual({ medium: 512 });
	});
});