import { beforeAll, describe, expect, it, vi } from "bun:test";
import type { AssistantMessage, Usage } from "@oh-my-pi/pi-ai";
import { BtwController } from "@oh-my-pi/pi-coding-agent/modes/controllers/btw-controller";
import { initTheme } from "@oh-my-pi/pi-coding-agent/modes/theme/theme";
import type { InteractiveModeContext } from "@oh-my-pi/pi-coding-agent/modes/types";
import { Container, type TUI } from "@oh-my-pi/pi-tui";

const usage: Usage = {
	input: 0,
	output: 0,
	cacheRead: 0,
	cacheWrite: 0,
	totalTokens: 0,
	cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
};

function createAssistantMessage(text: string): AssistantMessage {
	return {
		role: "assistant",
		content: [{ type: "text", text }],
		api: "anthropic-messages",
		provider: "anthropic",
		model: "claude-sonnet-4-5",
		usage,
		stopReason: "stop",
		timestamp: Date.now(),
	};
}

interface RunEphemeralTurnArgs {
	promptText: string;
	onTextDelta?: (delta: string) => void;
	signal?: AbortSignal;
}

interface RunEphemeralTurnResult {
	replyText: string;
	assistantMessage: AssistantMessage;
}

function makeFakeSession(
	runEphemeralTurn: (args: RunEphemeralTurnArgs) => Promise<RunEphemeralTurnResult>,
): InteractiveModeContext["session"] {
	return {
		model: { provider: "anthropic", id: "claude-sonnet-4-5" },
		runEphemeralTurn,
	} as unknown as InteractiveModeContext["session"];
}

function makeCtx(session: InteractiveModeContext["session"], btwContainer = new Container()): InteractiveModeContext {
	return {
		ui: { requestRender: vi.fn(), requestComponentRender: vi.fn() } as unknown as TUI,
		btwContainer,
		session,
		showStatus: vi.fn(),
		showError: vi.fn(),
	} as unknown as InteractiveModeContext;
}

beforeAll(async () => {
	await initTheme();
});

describe("BtwController", () => {
	it("dispatches the question to runEphemeralTurn with the btw prompt wrapper and a fresh signal", async () => {
		const runEphemeralTurn = vi.fn(async (_args: RunEphemeralTurnArgs) => ({
			replyText: "Answer",
			assistantMessage: createAssistantMessage("Answer"),
		}));
		const ctx = makeCtx(makeFakeSession(runEphemeralTurn));
		const controller = new BtwController(ctx);

		await controller.start("What changed?");
		// Drain microtasks so the inner promise can resolve.
		await Promise.resolve();
		await Promise.resolve();

		expect(runEphemeralTurn).toHaveBeenCalledTimes(1);
		const callArg = runEphemeralTurn.mock.calls[0]?.[0];
		expect(callArg).toBeDefined();
		expect(callArg?.promptText).toContain("<btw>");
		expect(callArg?.promptText).toContain("What changed?");
		expect(callArg?.signal).toBeInstanceOf(AbortSignal);
		expect(typeof callArg?.onTextDelta).toBe("function");
		expect(controller.hasActiveRequest()).toBe(true);
	});

	it("replaces a previous request by aborting it before issuing the next runEphemeralTurn", async () => {
		const signals: AbortSignal[] = [];
		let firstRelease!: () => void;
		const firstPromise = new Promise<RunEphemeralTurnResult>(resolve => {
			firstRelease = () => resolve({ replyText: "first", assistantMessage: createAssistantMessage("first") });
		});
		const runEphemeralTurn = vi
			.fn<(args: RunEphemeralTurnArgs) => Promise<RunEphemeralTurnResult>>()
			.mockImplementationOnce(async args => {
				signals.push(args.signal as AbortSignal);
				return firstPromise;
			})
			.mockImplementationOnce(async args => {
				signals.push(args.signal as AbortSignal);
				return { replyText: "second", assistantMessage: createAssistantMessage("second") };
			});
		const btwContainer = new Container();
		const ctx = makeCtx(makeFakeSession(runEphemeralTurn), btwContainer);
		const controller = new BtwController(ctx);

		await controller.start("First?");
		await controller.start("Second?");
		// Allow the second call to settle.
		await Promise.resolve();
		await Promise.resolve();

		expect(runEphemeralTurn).toHaveBeenCalledTimes(2);
		expect(signals[0]?.aborted).toBe(true);
		expect(signals[1]?.aborted).toBe(false);
		expect(btwContainer.children).toHaveLength(1);
		// Allow the orphaned first request to finish to keep the test clean.
		firstRelease();
	});

	it("clears the panel when the active request is dismissed via Escape", async () => {
		const runEphemeralTurn = vi.fn(async () => new Promise<RunEphemeralTurnResult>(() => {}));
		const btwContainer = new Container();
		const ctx = makeCtx(makeFakeSession(runEphemeralTurn), btwContainer);
		const controller = new BtwController(ctx);

		await controller.start("Question?");
		expect(btwContainer.children).toHaveLength(1);
		expect(controller.handleEscape()).toBe(true);
		expect(btwContainer.children).toHaveLength(0);
		expect(controller.hasActiveRequest()).toBe(false);
	});

	it("rejects empty questions before issuing the side-channel call", async () => {
		const runEphemeralTurn = vi.fn(async () => ({
			replyText: "n/a",
			assistantMessage: createAssistantMessage("n/a"),
		}));
		const ctx = makeCtx(makeFakeSession(runEphemeralTurn));
		const controller = new BtwController(ctx);

		await controller.start("   ");
		expect(runEphemeralTurn).not.toHaveBeenCalled();
		expect(controller.hasActiveRequest()).toBe(false);
	});

	it("shows an error message when no model is configured", async () => {
		const runEphemeralTurn = vi.fn(async () => ({
			replyText: "n/a",
			assistantMessage: createAssistantMessage("n/a"),
		}));
		const session = { model: undefined, runEphemeralTurn } as unknown as InteractiveModeContext["session"];
		const ctx = makeCtx(session);
		const controller = new BtwController(ctx);

		await controller.start("Anything?");
		expect(runEphemeralTurn).not.toHaveBeenCalled();
		expect(ctx.showError).toHaveBeenCalled();
	});
});