import { afterEach, beforeEach, describe, expect, test } from "bun:test";
import * as fs from "node:fs";
import * as os from "node:os";
import * as path from "node:path";
import { ModelRegistry } from "@oh-my-pi/pi-coding-agent/config/model-registry";
import { AuthStorage } from "@oh-my-pi/pi-coding-agent/session/auth-storage";
import { nanoid } from "nanoid";

describe("ModelRegistry", () => {
	let tempDir: string;
	let modelsJsonPath: string;
	let authStorage: AuthStorage;

	beforeEach(async () => {
		tempDir = path.join(os.tmpdir(), `pi-test-model-registry-${nanoid()}`);
		fs.mkdirSync(tempDir, { recursive: true });
		modelsJsonPath = path.join(tempDir, "models.json");
		authStorage = await AuthStorage.create(path.join(tempDir, "auth.json"));
	});

	afterEach(() => {
		if (tempDir && fs.existsSync(tempDir)) {
			fs.rmSync(tempDir, { recursive: true });
		}
	});

	/** Create minimal provider config  */
	function providerConfig(
		baseUrl: string,
		models: Array<{ id: string; name?: string }>,
		api: string = "anthropic-messages",
	) {
		return {
			baseUrl,
			apiKey: "TEST_KEY",
			api,
			models: models.map(m => ({
				id: m.id,
				name: m.name ?? m.id,
				reasoning: false,
				input: ["text"],
				cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
				contextWindow: 100000,
				maxTokens: 8000,
			})),
		};
	}

	function writeModelsJson(providers: Record<string, ReturnType<typeof providerConfig>>) {
		fs.writeFileSync(modelsJsonPath, JSON.stringify({ providers }));
	}

	function getModelsForProvider(registry: ModelRegistry, provider: string) {
		return registry.getAll().filter(m => m.provider === provider);
	}

	/** Create a baseUrl-only override (no custom models) */
	function overrideConfig(baseUrl: string, headers?: Record<string, string>) {
		return { baseUrl, ...(headers && { headers }) };
	}

	/** Write raw providers config (for mixed override/replacement scenarios) */
	function writeRawModelsJson(providers: Record<string, unknown>) {
		fs.writeFileSync(modelsJsonPath, JSON.stringify({ providers }));
	}

	describe("baseUrl override (no custom models)", () => {
		test("overriding baseUrl keeps all built-in models", async () => {
			writeRawModelsJson({
				anthropic: overrideConfig("https://my-proxy.example.com/v1"),
			});

			const registry = new ModelRegistry(authStorage, modelsJsonPath);
			const anthropicModels = getModelsForProvider(registry, "anthropic");

			// Should have multiple built-in models, not just one
			expect(anthropicModels.length).toBeGreaterThan(1);
			expect(anthropicModels.some(m => m.id.includes("claude"))).toBe(true);
		});

		test("overriding baseUrl changes URL on all built-in models", async () => {
			writeRawModelsJson({
				anthropic: overrideConfig("https://my-proxy.example.com/v1"),
			});

			const registry = new ModelRegistry(authStorage, modelsJsonPath);
			const anthropicModels = getModelsForProvider(registry, "anthropic");

			// All models should have the new baseUrl
			for (const model of anthropicModels) {
				expect(model.baseUrl).toBe("https://my-proxy.example.com/v1");
			}
		});

		test("overriding headers merges with model headers", async () => {
			writeRawModelsJson({
				anthropic: overrideConfig("https://my-proxy.example.com/v1", {
					"X-Custom-Header": "custom-value",
				}),
			});

			const registry = new ModelRegistry(authStorage, modelsJsonPath);
			const anthropicModels = getModelsForProvider(registry, "anthropic");

			for (const model of anthropicModels) {
				expect(model.headers?.["X-Custom-Header"]).toBe("custom-value");
			}
		});

		test("baseUrl-only override does not affect other providers", async () => {
			writeRawModelsJson({
				anthropic: overrideConfig("https://my-proxy.example.com/v1"),
			});

			const registry = new ModelRegistry(authStorage, modelsJsonPath);
			const googleModels = getModelsForProvider(registry, "google");

			// Google models should still have their original baseUrl
			expect(googleModels.length).toBeGreaterThan(0);
			expect(googleModels[0].baseUrl).not.toBe("https://my-proxy.example.com/v1");
		});

		test("can mix baseUrl override and full replacement", async () => {
			writeRawModelsJson({
				// baseUrl-only for anthropic
				anthropic: overrideConfig("https://anthropic-proxy.example.com/v1"),
				// Full replacement for google
				google: providerConfig(
					"https://google-proxy.example.com/v1",
					[{ id: "gemini-custom" }],
					"google-generative-ai",
				),
			});

			const registry = new ModelRegistry(authStorage, modelsJsonPath);

			// Anthropic: multiple built-in models with new baseUrl
			const anthropicModels = getModelsForProvider(registry, "anthropic");
			expect(anthropicModels.length).toBeGreaterThan(1);
			expect(anthropicModels[0].baseUrl).toBe("https://anthropic-proxy.example.com/v1");

			// Google: single custom model
			const googleModels = getModelsForProvider(registry, "google");
			expect(googleModels).toHaveLength(1);
			expect(googleModels[0].id).toBe("gemini-custom");
		});

		test("refresh() picks up baseUrl override changes", async () => {
			writeRawModelsJson({
				anthropic: overrideConfig("https://first-proxy.example.com/v1"),
			});
			const registry = new ModelRegistry(authStorage, modelsJsonPath);

			expect(getModelsForProvider(registry, "anthropic")[0].baseUrl).toBe("https://first-proxy.example.com/v1");

			// Update and refresh
			writeRawModelsJson({
				anthropic: overrideConfig("https://second-proxy.example.com/v1"),
			});
			await registry.refresh();

			expect(getModelsForProvider(registry, "anthropic")[0].baseUrl).toBe("https://second-proxy.example.com/v1");
		});
	});

	describe("provider replacement (with custom models)", () => {
		test("custom provider with same name as built-in replaces built-in models", async () => {
			writeModelsJson({
				anthropic: providerConfig("https://my-proxy.example.com/v1", [{ id: "claude-custom" }]),
			});

			const registry = new ModelRegistry(authStorage, modelsJsonPath);
			const anthropicModels = getModelsForProvider(registry, "anthropic");

			expect(anthropicModels).toHaveLength(1);
			expect(anthropicModels[0].id).toBe("claude-custom");
			expect(anthropicModels[0].baseUrl).toBe("https://my-proxy.example.com/v1");
		});

		test("custom provider with same name as built-in does not affect other built-in providers", async () => {
			writeModelsJson({
				anthropic: providerConfig("https://my-proxy.example.com/v1", [{ id: "claude-custom" }]),
			});

			const registry = new ModelRegistry(authStorage, modelsJsonPath);

			expect(getModelsForProvider(registry, "google").length).toBeGreaterThan(0);
			expect(getModelsForProvider(registry, "openai").length).toBeGreaterThan(0);
		});

		test("multiple built-in providers can be overridden", async () => {
			writeModelsJson({
				anthropic: providerConfig("https://anthropic-proxy.example.com/v1", [{ id: "claude-proxy" }]),
				google: providerConfig(
					"https://google-proxy.example.com/v1",
					[{ id: "gemini-proxy" }],
					"google-generative-ai",
				),
			});

			const registry = new ModelRegistry(authStorage, modelsJsonPath);
			const anthropicModels = getModelsForProvider(registry, "anthropic");
			const googleModels = getModelsForProvider(registry, "google");

			expect(anthropicModels).toHaveLength(1);
			expect(anthropicModels[0].id).toBe("claude-proxy");
			expect(anthropicModels[0].baseUrl).toBe("https://anthropic-proxy.example.com/v1");

			expect(googleModels).toHaveLength(1);
			expect(googleModels[0].id).toBe("gemini-proxy");
			expect(googleModels[0].baseUrl).toBe("https://google-proxy.example.com/v1");
		});

		test("refresh() reloads overrides from disk", async () => {
			writeModelsJson({
				anthropic: providerConfig("https://first-proxy.example.com/v1", [{ id: "claude-first" }]),
			});
			const registry = new ModelRegistry(authStorage, modelsJsonPath);

			expect(getModelsForProvider(registry, "anthropic")[0].id).toBe("claude-first");

			// Update and refresh
			writeModelsJson({
				anthropic: providerConfig("https://second-proxy.example.com/v1", [{ id: "claude-second" }]),
			});
			await registry.refresh();

			const anthropicModels = getModelsForProvider(registry, "anthropic");
			expect(anthropicModels[0].id).toBe("claude-second");
			expect(anthropicModels[0].baseUrl).toBe("https://second-proxy.example.com/v1");
		});

		test("removing override from models.json restores built-in provider", async () => {
			writeModelsJson({
				anthropic: providerConfig("https://proxy.example.com/v1", [{ id: "claude-custom" }]),
			});
			const registry = new ModelRegistry(authStorage, modelsJsonPath);

			expect(getModelsForProvider(registry, "anthropic")).toHaveLength(1);

			// Remove override and refresh
			writeModelsJson({});
			await registry.refresh();

			const anthropicModels = getModelsForProvider(registry, "anthropic");
			expect(anthropicModels.length).toBeGreaterThan(1);
			expect(anthropicModels.some(m => m.id.includes("claude"))).toBe(true);
		});
	});
});