import { afterEach, beforeEach, describe, expect, it } from "bun:test";
import * as fs from "node:fs";
import * as os from "node:os";
import * as path from "node:path";
import { SettingsManager } from "@oh-my-pi/pi-coding-agent/config/settings-manager";
import { YAML } from "bun";

describe("SettingsManager", () => {
	let testDir: string;
	let agentDir: string;
	let projectDir: string;

	beforeEach(() => {
		// Use random UUID to isolate parallel test runs (SQLite files can't be shared)
		testDir = path.join(os.tmpdir(), "test-settings-tmp", crypto.randomUUID());
		agentDir = path.join(testDir, "agent");
		projectDir = path.join(testDir, "project");

		if (fs.existsSync(testDir)) {
			fs.rmSync(testDir, { recursive: true });
		}
		fs.mkdirSync(agentDir, { recursive: true });
		fs.mkdirSync(path.join(projectDir, ".pi"), { recursive: true });
	});

	const getConfigPath = () => path.join(agentDir, "config.yml");

	const writeSettings = async (settings: Record<string, unknown>) => {
		await Bun.write(getConfigPath(), YAML.stringify(settings, null, 2));
	};

	const readSettings = async (): Promise<Record<string, unknown>> => {
		const file = Bun.file(getConfigPath());
		if (!(await file.exists())) return {};
		const content = await file.text();
		const parsed = YAML.parse(content);
		if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) return {};
		return parsed as Record<string, unknown>;
	};

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

	// Tests that SettingsManager merges with DB state on save rather than blindly overwriting.
	// This ensures external edits (via AgentStorage directly) aren't lost when the app saves.
	describe("preserves externally added settings", () => {
		it("should preserve enabledModels when changing thinking level", async () => {
			// Seed initial settings in config.yml
			await writeSettings({
				theme: "dark",
				modelRoles: { default: "claude-sonnet" },
			});

			// Manager loads the initial state
			const manager = await SettingsManager.create(projectDir, agentDir);

			// Simulate external edit (e.g., user modifying DB directly or another process)
			await writeSettings({
				theme: "dark",
				modelRoles: { default: "claude-sonnet" },
				enabledModels: ["claude-opus-4-5", "gpt-5.2-codex"],
			});

			// Manager saves a change - should merge, not overwrite
			await manager.setDefaultThinkingLevel("high");

			const savedSettings = await readSettings();
			expect(savedSettings.enabledModels).toEqual(["claude-opus-4-5", "gpt-5.2-codex"]);
			expect(savedSettings.defaultThinkingLevel).toBe("high");
			expect(savedSettings.theme).toBe("dark");
			expect((savedSettings.modelRoles as { default?: string } | undefined)?.default).toBe("claude-sonnet");
		});

		it("should preserve custom settings when changing theme", async () => {
			await writeSettings({
				modelRoles: { default: "claude-sonnet" },
			});

			const manager = await SettingsManager.create(projectDir, agentDir);

			await writeSettings({
				modelRoles: { default: "claude-sonnet" },
				shellPath: "/bin/zsh",
				extensions: ["/path/to/extension.ts"],
			});

			await manager.setTheme("light");

			const savedSettings = await readSettings();
			expect(savedSettings.shellPath).toBe("/bin/zsh");
			expect(savedSettings.extensions).toEqual(["/path/to/extension.ts"]);
			expect(savedSettings.theme).toBe("light");
		});

		it("should let in-memory changes override file changes for same key", async () => {
			await writeSettings({
				theme: "dark",
			});

			const manager = await SettingsManager.create(projectDir, agentDir);

			await writeSettings({
				theme: "dark",
				defaultThinkingLevel: "low",
			});

			await manager.setDefaultThinkingLevel("high");

			const savedSettings = await readSettings();
			expect(savedSettings.defaultThinkingLevel).toBe("high");
		});
	});
});