import { beforeAll, describe, expect, it } from 'vitest';
import { readFileSync } from 'node:fs';
import { resolve } from 'node:path';
import vm from 'node:vm';
import {
  availableTransformEngines,
  runTransformation,
} from '../src/transform/transformService';
import { compileXsltTextToSefJson } from '../src/transform/saxonJsDynamicCompiler';

const xmlText = `<?xml version="1.0" encoding="UTF-8"?>
<library>
  <book id="b1"><title>Practical XSLT</title><author>Ada</author></book>
  <book id="b2"><title>Browser XML</title><author>Lin</author></book>
</library>`;

const xslt10Text = `<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" omit-xml-declaration="yes"/>
  <xsl:template match="/library">
    <titles><xsl:for-each select="book"><title><xsl:value-of select="title"/></title></xsl:for-each></titles>
  </xsl:template>
</xsl:stylesheet>`;

const xslt20Text = `<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" omit-xml-declaration="yes"/>
  <xsl:template match="/library">
    <books><xsl:value-of select="upper-case(string-join(book/title, '|'))"/></books>
  </xsl:template>
</xsl:stylesheet>`;

const xslt30Text = `<xsl:stylesheet version="3.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" omit-xml-declaration="yes"/>
  <xsl:mode on-no-match="shallow-copy"/>
  <xsl:template match="book/title/text()">
    <xsl:value-of select="upper-case(.)"/>
  </xsl:template>
</xsl:stylesheet>`;

beforeAll(() => {
  if (window.SaxonJS) return;

  const scriptPath = resolve(process.cwd(), 'public/vendor/saxon/SaxonJS2.js');
  const script = readFileSync(scriptPath, 'utf8');
  vm.runInContext(script, vm.createContext(window));
});

describe('transform engine registry', () => {
  it('keeps the native browser XSLTProcessor engine selectable', () => {
    expect(availableTransformEngines.map((engine) => engine.id)).toContain(
      'native-xsltprocessor'
    );
  });

  it('exposes the dynamic SaxonJS engine for XSLT 2.0/3.0', () => {
    expect(availableTransformEngines.map((engine) => engine.id)).toContain(
      'saxon-js-dynamic'
    );
  });
});

describe('SaxonJS dynamic compiler', () => {
  it('compiles raw XSLT text to SEF JSON', async () => {
    const sef = await compileXsltTextToSefJson(xslt30Text);
    const parsed = JSON.parse(sef) as { N?: string; target?: string };

    expect(parsed.N).toBe('package');
    expect(parsed.target).toBe('JS');
  });

  it('runs an XSLT 1.0 stylesheet', async () => {
    const result = await runTransformation({
      xmlText,
      xsltText: xslt10Text,
      engine: 'saxon-js-dynamic',
    });

    expect(
      result.diagnostics.filter((item) => item.severity === 'error')
    ).toHaveLength(0);
    expect(result.output).toContain('<title>Practical XSLT</title>');
    expect(result.output).toContain('<title>Browser XML</title>');
  });

  it('runs an XSLT 2.0 stylesheet with XPath 2.0 functions', async () => {
    const result = await runTransformation({
      xmlText,
      xsltText: xslt20Text,
      engine: 'saxon-js-dynamic',
    });

    expect(
      result.diagnostics.filter((item) => item.severity === 'error')
    ).toHaveLength(0);
    expect(result.output).toContain('PRACTICAL XSLT|BROWSER XML');
  });

  it('runs an XSLT 3.0 stylesheet with xsl:mode on-no-match', async () => {
    const result = await runTransformation({
      xmlText,
      xsltText: xslt30Text,
      engine: 'saxon-js-dynamic',
    });

    expect(
      result.diagnostics.filter((item) => item.severity === 'error')
    ).toHaveLength(0);
    expect(result.output).toContain('<title>PRACTICAL XSLT</title>');
    expect(result.output).toContain('<title>BROWSER XML</title>');
  });

  it('returns diagnostics for invalid XSLT', async () => {
    const result = await runTransformation({
      xmlText,
      xsltText: '<xsl:stylesheet version="3.0">',
      engine: 'saxon-js-dynamic',
    });

    expect(result.diagnostics.some((item) => item.severity === 'error')).toBe(
      true
    );
  });
});