// @vitest-environment jsdom
import { installCanvasMock } from '$shared/lib/helpers/__mocks__/canvas';
import { clearCache } from '@chenglou/pretext';
import {
    beforeEach,
    describe,
    expect,
    it,
} from 'vitest';
import { DualFontLayout } from './DualFontLayout';

// FontA: 10px per character. FontB: 15px per character.
// The mock dispatches on whether the font string contains 'FontA' or 'FontB'.
const FONT_A_WIDTH = 10;
const FONT_B_WIDTH = 15;

function fontWidthFactory(font: string, text: string): number {
    const perChar = font.includes('FontA') ? FONT_A_WIDTH : FONT_B_WIDTH;
    return text.length * perChar;
}

describe('DualFontLayout', () => {
    let layout: DualFontLayout;

    beforeEach(() => {
        installCanvasMock(fontWidthFactory);
        clearCache();
        layout = new DualFontLayout();
    });

    it('returns empty result for empty string', () => {
        const result = layout.layout('', '400 16px "FontA"', '400 16px "FontB"', 500, 20);
        expect(result.lines).toHaveLength(0);
        expect(result.totalHeight).toBe(0);
    });

    it('uses worst-case width across both fonts to determine line breaks', () => {
        // 'AB CD' — two 2-char words separated by a space.
        // FontA: 'AB'=20px, 'CD'=20px. Both fit in 25px? No: 'AB CD' = 50px total.
        // FontB: 'AB'=30px, 'CD'=30px. Width 35px forces wrap after 'AB '.
        // Unified must use FontB widths — so it must wrap at the same place FontB wraps.
        const result = layout.layout('AB CD', '400 16px "FontA"', '400 16px "FontB"', 35, 20);
        expect(result.lines.length).toBeGreaterThan(1);
        // First line text must not include both words.
        expect(result.lines[0].text).not.toContain('CD');
    });

    it('provides xA and xB offsets for both fonts on a single line', () => {
        // 'ABC' fits in 500px for both fonts.
        // FontA: A@0(w=10), B@10(w=10), C@20(w=10)
        // FontB: A@0(w=15), B@15(w=15), C@30(w=15)
        const result = layout.layout('ABC', '400 16px "FontA"', '400 16px "FontB"', 500, 20);
        const chars = result.lines[0].chars;

        expect(chars).toHaveLength(3);

        expect(chars[0].xA).toBe(0);
        expect(chars[0].widthA).toBe(FONT_A_WIDTH);
        expect(chars[0].xB).toBe(0);
        expect(chars[0].widthB).toBe(FONT_B_WIDTH);

        expect(chars[1].xA).toBe(FONT_A_WIDTH); // 10
        expect(chars[1].widthA).toBe(FONT_A_WIDTH);
        expect(chars[1].xB).toBe(FONT_B_WIDTH); // 15
        expect(chars[1].widthB).toBe(FONT_B_WIDTH);

        expect(chars[2].xA).toBe(FONT_A_WIDTH * 2); // 20
        expect(chars[2].xB).toBe(FONT_B_WIDTH * 2); // 30
    });

    it('returns cached result when called again with same arguments', () => {
        const r1 = layout.layout('ABC', '400 16px "FontA"', '400 16px "FontB"', 500, 20);
        const r2 = layout.layout('ABC', '400 16px "FontA"', '400 16px "FontB"', 500, 20);
        expect(r2).toBe(r1); // strict reference equality — same object
    });

    it('re-computes when text changes', () => {
        const r1 = layout.layout('ABC', '400 16px "FontA"', '400 16px "FontB"', 500, 20);
        const r2 = layout.layout('DEF', '400 16px "FontA"', '400 16px "FontB"', 500, 20);
        expect(r2).not.toBe(r1);
        expect(r2.lines[0].text).not.toBe(r1.lines[0].text);
    });

    it('re-computes when width changes', () => {
        const r1 = layout.layout('Hello World', '400 16px "FontA"', '400 16px "FontB"', 500, 20);
        const r2 = layout.layout('Hello World', '400 16px "FontA"', '400 16px "FontB"', 60, 20);
        expect(r2).not.toBe(r1);
    });

    it('re-computes when fontA changes', () => {
        const r1 = layout.layout('ABC', '400 16px "FontA"', '400 16px "FontB"', 500, 20);
        const r2 = layout.layout('ABC', '400 24px "FontA"', '400 16px "FontB"', 500, 20);
        expect(r2).not.toBe(r1);
    });
});