/**
 * configFile.test.ts
 * ------------------
 * Unit tests for the JSON config-file loader.
 * Run via `bun test` (or `bun run test`).
 */

import { afterAll, beforeAll, describe, expect, test } from "bun:test";
import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";

import { loadConfigFile } from "../src/configFile.ts";
import { CliError } from "../src/errors.ts";

let TMP: string;

beforeAll(() => {
    TMP = mkdtempSync(join(tmpdir(), "move-cfg-test-"));
});

afterAll(() => {
    rmSync(TMP, { recursive: true, force: true });
});

function writeFixture(name: string, body: string): string {
    const p = join(TMP, name);
    writeFileSync(p, body);
    return p;
}

describe("loadConfigFile (explicit path)", () => {
    test("returns parsed overrides for a valid file", () => {
        const path = writeFixture(
            "valid.json",
            JSON.stringify({ moveInterval: 60, verbose: true }),
        );
        const result = loadConfigFile(path);
        expect(result).not.toBeNull();
        // The bang is justified by the not-null assertion above.
        expect(result!.moveInterval).toBe(60);
        expect(result!.verbose).toBe(true);
        // Fields not in the file are undefined.
        expect(result!.checkInterval).toBeUndefined();
        expect(result!.stepDelay).toBeUndefined();
        expect(result!.stepCount).toBeUndefined();
    });

    test("returns all-undefined overrides for an empty object", () => {
        const path = writeFixture("empty.json", "{}");
        const result = loadConfigFile(path);
        expect(result).not.toBeNull();
        expect(result!.moveInterval).toBeUndefined();
        expect(result!.verbose).toBeUndefined();
    });

    test("throws CliError when explicit path does not exist", () => {
        expect(() => loadConfigFile(join(TMP, "missing.json"))).toThrow(CliError);
    });

    test("throws on malformed JSON, mentioning the file path", () => {
        const path = writeFixture("bad-json.json", "this is not json");
        expect(() => loadConfigFile(path)).toThrow(/is not valid JSON/);
        expect(() => loadConfigFile(path)).toThrow(new RegExp(path.replace(/[.]/g, "\\.")));
    });

    test("throws when root is not an object (e.g. array)", () => {
        const path = writeFixture("array.json", "[1, 2, 3]");
        expect(() => loadConfigFile(path)).toThrow(/JSON object at the root/);
    });

    test("throws when root is not an object (e.g. string)", () => {
        const path = writeFixture("string.json", "\"hello\"");
        expect(() => loadConfigFile(path)).toThrow(/JSON object at the root/);
    });

    test("throws on an unknown key, naming the typo and the allowed set", () => {
        const path = writeFixture("typo.json", JSON.stringify({ movInterval: 60 }));
        expect(() => loadConfigFile(path)).toThrow(/unknown key 'movInterval'/);
        expect(() => loadConfigFile(path)).toThrow(/moveInterval/);
    });

    test("throws on non-positive numeric values", () => {
        const negative = writeFixture("neg.json", JSON.stringify({ stepCount: -1 }));
        expect(() => loadConfigFile(negative)).toThrow(/'stepCount'.*positive number/);

        const zero = writeFixture("zero.json", JSON.stringify({ stepDelay: 0 }));
        expect(() => loadConfigFile(zero)).toThrow(/'stepDelay'.*positive number/);
    });

    test("throws when a numeric field has the wrong type", () => {
        const path = writeFixture("type.json", JSON.stringify({ moveInterval: "60" }));
        expect(() => loadConfigFile(path)).toThrow(/'moveInterval'.*positive number/);
    });

    test("throws when verbose is the wrong type", () => {
        const path = writeFixture("verbose.json", JSON.stringify({ verbose: "yes" }));
        expect(() => loadConfigFile(path)).toThrow(/'verbose'.*boolean/);
    });
});

describe("loadConfigFile (default path)", () => {
    let savedXdg: string | undefined;

    beforeAll(() => {
        savedXdg = process.env.XDG_CONFIG_HOME;
        // Point the default path under the test tmpdir so a missing file is
        // guaranteed (we never create $TMP/move/config.json).
        process.env.XDG_CONFIG_HOME = TMP;
    });

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

    test("returns null when no file exists at the default path", () => {
        expect(loadConfigFile(undefined)).toBeNull();
    });
});