/**
 * Marker accounting.
 *
 * This is the logic that decides which queued images actually reach the model,
 * so it gets a test even though it is small: a wrong count either silently
 * sends an image the user deleted from their draft, or drops one they kept.
 *
 * Mirrors the reduction in index.ts. Kept as a pure function here so the rule
 * can be tested without booting a pi session.
 */

import assert from "node:assert/strict";
import { test } from "node:test";

const MARKER = "[wl-image]";

interface Queued {
	id: string;
}

/** Returns the images to send and the queue that survives to the next message. */
function resolveAttachments(
	text: string,
	pending: Queued[],
): { attached: Queued[]; remaining: Queued[]; text: string } {
	const markers = text.split(MARKER).length - 1;
	if (markers === 0) return { attached: [], remaining: pending, text };
	const queue = [...pending];
	const attached = queue.splice(0, markers);
	return {
		attached,
		remaining: queue,
		text: text.replaceAll(MARKER, "").replace(/\s+/g, " ").trim(),
	};
}

test("one marker sends the one queued image", () => {
	const result = resolveAttachments(`look at this ${MARKER}`, [{ id: "a" }]);
	assert.deepEqual(result.attached, [{ id: "a" }]);
	assert.deepEqual(result.remaining, []);
	assert.equal(result.text, "look at this");
});

test("deleting the marker cancels the attachment", () => {
	// The user removed the marker from the draft, so the image must not be sent.
	const result = resolveAttachments("look at this", [{ id: "a" }]);
	assert.deepEqual(result.attached, []);
});

test("deleting one of two markers sends only one image", () => {
	const result = resolveAttachments(`compare ${MARKER}`, [{ id: "a" }, { id: "b" }]);
	assert.deepEqual(result.attached, [{ id: "a" }]);
	// The unsent image stays queued rather than being silently thrown away.
	assert.deepEqual(result.remaining, [{ id: "b" }]);
});

test("more markers than images does not invent attachments", () => {
	const result = resolveAttachments(`${MARKER} ${MARKER} ${MARKER}`, [{ id: "a" }]);
	assert.deepEqual(result.attached, [{ id: "a" }]);
	assert.deepEqual(result.remaining, []);
});

test("markers are stripped and whitespace collapsed", () => {
	const result = resolveAttachments(`${MARKER}  what   is  this? ${MARKER}`, [
		{ id: "a" },
		{ id: "b" },
	]);
	assert.equal(result.text, "what is this?");
	assert.equal(result.attached.length, 2);
});

test("a marker-only message leaves empty text for the caller to fill", () => {
	const result = resolveAttachments(MARKER, [{ id: "a" }]);
	assert.equal(result.text, "");
	assert.equal(result.attached.length, 1);
});

test("no markers leaves the queue and text untouched", () => {
	const pending = [{ id: "a" }];
	const result = resolveAttachments("unrelated question", pending);
	assert.deepEqual(result.remaining, pending);
	assert.equal(result.text, "unrelated question");
});