// Tests for the document→layout glue (P0.5 step 10, automatable slice):
// fit-to-width metrics built from a fake PageDocumentSource. No pdfium.

import 'dart:ui' show Size;

import 'package:flutter_test/flutter_test.dart';

import 'package:badnote/editor/layout/page_viewport.dart';
import 'package:badnote/editor/pdf/pdf_document_source.dart';

class _FakeSource implements PageDocumentSource {
  _FakeSource(this._sizes);
  final List<Size> _sizes;
  @override
  int get pageCount => _sizes.length;
  @override
  Size pageSize(int index) => _sizes[index];
}

void main() {
  test('fit-to-width scales each page height by its aspect at the column width',
      () {
    // A4-ish portrait 600×800 and a square 500×500 at column width 300.
    final source = _FakeSource([const Size(600, 800), const Size(500, 500)]);
    final m = pageStackMetricsForWidth(source, 300);
    expect(m.pageCount, 2);
    expect(m.heightOf(0), closeTo(300 * 800 / 600, 1e-9)); // 400
    expect(m.heightOf(1), closeTo(300.0, 1e-9)); // square → 300
    expect(m.totalExtent, closeTo(700, 1e-9));
  });

  test('gap is threaded into the metrics', () {
    final source = _FakeSource([const Size(100, 100), const Size(100, 100)]);
    final m = pageStackMetricsForWidth(source, 100, gap: 25);
    expect(m.offsetOf(1), closeTo(125, 1e-9)); // 100 + 25 gap
  });

  test('empty document yields empty metrics', () {
    final m = pageStackMetricsForWidth(_FakeSource(const []), 300);
    expect(m.pageCount, 0);
    expect(m.totalExtent, 0);
  });

  test('non-positive page width is treated as zero height (no divide-by-zero)',
      () {
    final source = _FakeSource([const Size(0, 800), const Size(400, 200)]);
    final m = pageStackMetricsForWidth(source, 300);
    expect(m.heightOf(0), 0.0);
    expect(m.heightOf(1), closeTo(150, 1e-9)); // 300 * 200/400
  });

  test('windowing composes on top of the fit-to-width metrics', () {
    // 5 portrait pages 600×800 at width 300 → each 400 tall, total 2000.
    final source =
        _FakeSource(List.filled(5, const Size(600, 800)));
    final m = pageStackMetricsForWidth(source, 300);
    expect(m.totalExtent, closeTo(2000, 1e-9));
    // viewport [350, 850) → page1 [400,800) and page2 [800,1200) just touched?
    // page0 [0,400), page1 [400,800), page2 [800,1200). window [350,850]:
    // first bottom>350 → page0 bottom 400>350 → 0; last top<850 → page2 top
    // 800<850 → 2.
    expect(m.visibleRange(350, 500), const PageWindow(0, 2));
  });
}