/**
 * config.test.ts
 * --------------
 * Unit tests for the layered config resolver and the default-path helper.
 * Run via `bun test` (or `bun run test`).
 */

import { afterEach, beforeEach, describe, expect, test } from "bun:test";

import { DEFAULT_CONFIG, defaultConfigPath, resolveConfig } from "../src/config.ts";
import type { ConfigOverrides } from "../src/config.ts";
import { CliError } from "../src/errors.ts";

const NONE: ConfigOverrides = {
    moveInterval: undefined,
    checkInterval: undefined,
    stepDelay: undefined,
    stepCount: undefined,
    verbose: undefined,
};

describe("resolveConfig", () => {
    test("returns DEFAULT_CONFIG when neither layer supplies a value", () => {
        expect(resolveConfig(null, NONE)).toEqual(DEFAULT_CONFIG);
    });

    test("CLI value wins over file value", () => {
        const file: ConfigOverrides = { ...NONE, moveInterval: 60 };
        const cli: ConfigOverrides = { ...NONE, moveInterval: 30 };
        const cfg = resolveConfig(file, cli);
        expect(cfg.moveInterval).toBe(30 * 1000); // CLI 30s -> 30000ms
    });

    test("file value wins over default when CLI is undefined", () => {
        const file: ConfigOverrides = { ...NONE, moveInterval: 60 };
        const cfg = resolveConfig(file, NONE);
        expect(cfg.moveInterval).toBe(60 * 1000); // file 60s -> 60000ms
    });

    test("seconds-to-ms conversion at the boundary for time-valued fields", () => {
        const cli: ConfigOverrides = { ...NONE, moveInterval: 5, checkInterval: 2 };
        const cfg = resolveConfig(null, cli);
        expect(cfg.moveInterval).toBe(5000);
        expect(cfg.checkInterval).toBe(2000);
    });

    test("stepDelay and stepCount pass through untouched (no unit conversion)", () => {
        const cli: ConfigOverrides = { ...NONE, stepDelay: 75, stepCount: 100 };
        const cfg = resolveConfig(null, cli);
        expect(cfg.stepDelay).toBe(75);
        expect(cfg.stepCount).toBe(100);
    });

    test("verbose: CLI true wins over file false", () => {
        const cfg = resolveConfig(
            { ...NONE, verbose: false },
            { ...NONE, verbose: true },
        );
        expect(cfg.verbose).toBe(true);
    });

    test("verbose: file true wins over default (no CLI)", () => {
        const cfg = resolveConfig({ ...NONE, verbose: true }, NONE);
        expect(cfg.verbose).toBe(true);
    });

    test("verbose: file false wins over default (no CLI)", () => {
        const cfg = resolveConfig({ ...NONE, verbose: false }, NONE);
        expect(cfg.verbose).toBe(false);
    });

    test("verbose: falls back to DEFAULT_CONFIG.verbose when neither set", () => {
        const cfg = resolveConfig(null, NONE);
        expect(cfg.verbose).toBe(DEFAULT_CONFIG.verbose);
    });
});

describe("defaultConfigPath", () => {
    let savedXdg: string | undefined;
    let savedHome: string | undefined;

    beforeEach(() => {
        savedXdg = process.env.XDG_CONFIG_HOME;
        savedHome = process.env.HOME;
    });

    afterEach(() => {
        if (savedXdg === undefined) delete process.env.XDG_CONFIG_HOME;
        else process.env.XDG_CONFIG_HOME = savedXdg;
        if (savedHome === undefined) delete process.env.HOME;
        else process.env.HOME = savedHome;
    });

    test("honors XDG_CONFIG_HOME when set", () => {
        process.env.XDG_CONFIG_HOME = "/custom/xdg";
        process.env.HOME = "/should/not/be/used";
        expect(defaultConfigPath()).toBe("/custom/xdg/move/config.json");
    });

    test("falls back to $HOME/.config when XDG_CONFIG_HOME is unset", () => {
        delete process.env.XDG_CONFIG_HOME;
        process.env.HOME = "/u/test";
        expect(defaultConfigPath()).toBe("/u/test/.config/move/config.json");
    });

    test("treats empty XDG_CONFIG_HOME as unset (per XDG spec)", () => {
        process.env.XDG_CONFIG_HOME = "";
        process.env.HOME = "/u/test";
        expect(defaultConfigPath()).toBe("/u/test/.config/move/config.json");
    });

    test("throws CliError when both XDG_CONFIG_HOME and HOME are unset", () => {
        delete process.env.XDG_CONFIG_HOME;
        delete process.env.HOME;
        expect(() => defaultConfigPath()).toThrow(CliError);
    });

    test("throws CliError when both XDG_CONFIG_HOME and HOME are empty", () => {
        process.env.XDG_CONFIG_HOME = "";
        process.env.HOME = "";
        expect(() => defaultConfigPath()).toThrow(CliError);
    });
});