import assert from 'node:assert/strict';

import test from 'node:test';

import { effect, reactive, ref, stop } from 'vue';

import { createReaderViewport } from '../../src/features/reader/reader-viewport.mjs';

function readerViewport(bounds) {

const pages = ref(reactive([1, 2, 3].map((number) => ({ number, visible: 0 }))));

const layout = {

columns: 1,

rows: [0, 1, 2].map((i) => ({ offset: i * 110, extent: 100, start: i, end: i + 1 })),

frames: [0, 1, 2].map((i) => ({ number: i + 1, x: 0, y: i * 110, width: 100, height: 100 })),

};

const rect = (r) => ({ getBoundingClientRect: () => r });

const renderState = {

layoutElement: { value: rect({ left: 0, top: 0 }) },

renderMetrics: { viewportLookups: 0, geometryReads: 0 },

visiblePages: new Set(),

renderWindow: ref(new Set()),

canvasEls: new Map(),

};

const viewport = createReaderViewport({

renderState,

session: { pages, restoringView: { value: false } },

motion: { pinching: { value: false }, referenceReturn: { value: null } },

view: { reader: { value: rect(bounds) }, pageLayout: { value: layout }, active: ref(1) },

activity: { foreground: { value: true } },

actions: { canvasRendering: { releaseCanvas() {} } },

});

return { pages, viewport };

}

test('repeating an unchanged viewport lookup does not touch page visibility', () => {

const { pages, viewport } = readerViewport({ left: 0, right: 100, top: 50, bottom: 150 });

viewport.viewportPages();

let runs = 0;

const runner = effect(() => {

for (const page of pages.value) void page.visible;

runs++;

});

runs = 0;

viewport.viewportPages();

stop(runner);

// A reset-then-restore would re-run pageLayout and schedule another lookup.

assert.equal(runs, 0);

assert.deepEqual(

pages.value.map((page) => page.visible),

[0.5, 0.4, 0],

);

});

test('pages that scroll out of the viewport are cleared', () => {

const bounds = { left: 0, right: 100, top: 50, bottom: 150 };

const { pages, viewport } = readerViewport(bounds);

viewport.viewportPages();

Object.assign(bounds, { top: 220, bottom: 320 });

viewport.viewportPages();

assert.deepEqual(

pages.value.map((page) => page.visible),

[0, 0, 1],

);

});