// Validates an exported package against the vendored schemas (tests/schemas/) through
// xmllint — the ODF 1.3 RelaxNG and the ECMA-376 XSDs, the structural half of what Word's
// strict reader enforces and LibreOffice forgives. Callers self-skip without `hasXmllint`.
import { spawnSync } from 'node:child_process';
import { mkdtempSync, writeFileSync } from 'node:fs';
import { tmpdir } from 'node:os';
import { join, resolve } from 'node:path';
import { fileURLToPath } from 'node:url';
import { strFromU8 } from 'fflate';

export const hasXmllint = spawnSync('xmllint', ['--version']).status === 0;
const SCHEMAS = resolve(fileURLToPath(import.meta.url), '..', 'schemas');
const MC_NS = 'http://schemas.openxmlformats.org/markup-compatibility/2006';
// A DrawingML text box (wps:wsp inside a:graphicData) is post-ECMA-376 Microsoft
// markup Word accepts natively; no ECMA schema covers it, so it is stripped like an
// ignorable — its inner w:p content is exercised by the body paragraphs instead.
const WPS_NS = 'http://schemas.microsoft.com/office/word/2010/wordprocessingShape';

// The namespaces the ODF 1.2 schema defines. Anything else (loext, …) is a foreign
// element/attribute an "extended conforming" consumer removes before validating.
const ODF_NS = new Set([
  'urn:oasis:names:tc:opendocument:xmlns:office:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:style:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:text:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:table:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:drawing:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:xsl-fo-compatible:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:meta:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:datastyle:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:svg-compatible:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:chart:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:dr3d:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:form:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:script:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:config:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:database:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:presentation:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:animation:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:smil-compatible:1.0',
  'urn:oasis:names:tc:opendocument:xmlns:manifest:1.0',
  'http://purl.org/dc/elements/1.1/',
  'http://www.w3.org/1998/Math/MathML',
  'http://www.w3.org/1999/xlink',
  'http://www.w3.org/1999/xhtml',
  'http://www.w3.org/2002/xforms',
  'http://www.w3.org/2003/g/data-view#',
  'http://www.w3.org/XML/1998/namespace',
  'http://www.w3.org/2000/xmlns/',
]);

// Removes foreign elements and attributes: keep what `keep(ns)` allows, drop the rest.
// For OOXML `keep` is "not declared mc:Ignorable"; for ODF it is the ODF_NS whitelist.
function stripForeign(xml: string, keep: (ns: string | null) => boolean): string {
  const doc = new DOMParser().parseFromString(xml, 'application/xml');
  const prune = (el: Element): void => {
    for (const child of [...el.children]) {
      if (child.namespaceURI === MC_NS && child.localName === 'AlternateContent') {
        // An ECMA-376-only consumer takes the Fallback branch.
        const fb = [...child.children].find(
          (c) => c.namespaceURI === MC_NS && c.localName === 'Fallback');
        for (const inner of fb ? [...fb.children] : []) el.insertBefore(inner, child);
        el.removeChild(child);
        continue;
      }
      if (!keep(child.namespaceURI)) { el.removeChild(child); continue; }
      prune(child);
    }
    for (const attr of [...el.attributes]) {
      if (attr.namespaceURI === MC_NS
        || (attr.namespaceURI && !keep(attr.namespaceURI))) el.removeAttributeNode(attr);
    }
  };
  prune(doc.documentElement);
  return new XMLSerializer().serializeToString(doc);
}

// The namespace URIs a part's root declares mc:Ignorable — an MCE consumer removes
// their elements and attributes before schema validation, exactly as Word reads them.
function mceIgnorable(xml: string): Set<string> {
  const doc = new DOMParser().parseFromString(xml, 'application/xml');
  const root = doc.documentElement;
  const out = new Set<string>([MC_NS]);
  const ig = root.getAttributeNS(MC_NS, 'Ignorable') ?? '';
  for (const prefix of ig.trim().split(/\s+/).filter(Boolean)) {
    const uri = root.getAttribute(`xmlns:${prefix}`);
    if (uri) out.add(uri);
  }
  out.add(WPS_NS);
  return out;
}

type Part = { label: string; xml: string };
let tmp: string | null = null;

// One xmllint run per schema: parsing the schema is what costs, so every part it
// covers rides the same call. Returns the failures, one entry per schema.
function validate(schema: string, kind: 'xsd' | 'rng', parts: Part[]): string[] {
  if (!parts.length) return [];
  tmp ??= mkdtempSync(join(tmpdir(), 'edentext-schema-'));
  const files = parts.map((p) => {
    const file = join(tmp!, `${p.label.replace(/[^\w.-]+/g, '_')}.xml`);
    writeFileSync(file, p.xml);
    return file;
  });
  const flag = kind === 'xsd' ? '--schema' : '--relaxng';
  const r = spawnSync('xmllint', ['--noout', '--nonet', flag, join(SCHEMAS, schema), ...files],
    { encoding: 'utf8', maxBuffer: 64 * 1024 * 1024 });
  if (r.status === 0) return [];
  const out = (r.stderr || r.stdout || `exit ${r.status}`).split('\n')
    .filter((line) => !/ validates$/.test(line)).join('\n');
  return [`${schema}:\n${out.slice(0, 4000)}`];
}

// Every XML part of an unzipped .odt against the ODF schema (foreign namespaces
// stripped, as extended conformance allows). Formula sub-documents root math:math,
// which the schema's start pattern excludes; mimetype and Pictures/ are not XML.
// libxml2's RelaxNG cannot match an element the schema declares by name *class* inside a
// <text:span> — the ODF statistic fields share one <rng:element><rng:choice>, and probed,
// text:creator (its own name=) in the same span validates. LibreOffice writes the span
// too, so the field is unwrapped for the check rather than avoided in the export.
const STAT_FIELD_SPAN =
  /<text:span\b[^>]*>(<text:(?:page|paragraph|word|character|table|image|object)-count\b[^>]*(?:\/>|>[^<]*<\/text:[a-z-]+>))<\/text:span>/g;

export function validateOdt(files: Record<string, Uint8Array>): string[] {
  const keepOdf = (ns: string | null) => ns == null || ODF_NS.has(ns);
  const docs: Part[] = [];
  const manifests: Part[] = [];
  for (const [name, bytes] of Object.entries(files)) {
    const part = { label: `odt ${name}`, xml: stripForeign(strFromU8(bytes), keepOdf).replace(STAT_FIELD_SPAN, '$1') };
    if (/^(content|styles|meta|settings)\.xml$/.test(name)) docs.push(part);
    else if (name === 'META-INF/manifest.xml') manifests.push(part);
  }
  return [
    ...validate('odf/OpenDocument-v1.3-schema.rng', 'rng', docs),
    ...validate('odf/OpenDocument-v1.3-manifest-schema.rng', 'rng', manifests),
  ];
}

function docxPartSchema(name: string): string | null {
  if (/^word\/(document|styles|numbering|settings|fontTable|footnotes|endnotes|comments|header\d+|footer\d+)\.xml$/.test(name)) return 'ooxml/wml.xsd';
  if (name === 'docProps/core.xml') return 'opc/opc-coreProperties.xsd';
  if (name === 'docProps/app.xml') return 'ooxml/shared-documentPropertiesExtended.xsd';
  if (name === 'docProps/custom.xml') return 'ooxml/shared-documentPropertiesCustom.xsd';
  // commentsExtended is a Microsoft w15 part with no ECMA-376 schema.
  if (name === 'word/commentsExtended.xml') return null;
  if (name === '[Content_Types].xml') return 'opc/opc-contentTypes.xsd';
  if (/(^|\/)_rels\/[^/]+$/.test(name)) return 'opc/opc-relationships.xsd';
  if (/^customXml\/itemProps\d+\.xml$/.test(name)) return 'ooxml/shared-customXmlDataProperties.xsd';
  if (/^customXml\/item\d+\.xml$/.test(name)) return 'ooxml/shared-bibliography.xsd';
  if (/^word\/(media|fonts)\//.test(name)) return null; // binary
  return `UNMAPPED:${name}`; // a new part must be mapped or listed here
}

// Every part of an unzipped .docx against its schema after MCE resolution, as Word
// reads it.
export function validateDocx(files: Record<string, Uint8Array>): string[] {
  const failures: string[] = [];
  const bySchema = new Map<string, Part[]>();
  for (const [name, bytes] of Object.entries(files)) {
    if (name.endsWith('/')) continue; // zip directory entry
    const schema = docxPartSchema(name);
    if (schema == null) continue;
    if (schema.startsWith('UNMAPPED:')) { failures.push(schema); continue; }
    const xml = strFromU8(bytes);
    const ignorable = mceIgnorable(xml);
    const part = { label: `docx ${name}`, xml: stripForeign(xml, (ns) => !ns || !ignorable.has(ns)) };
    bySchema.set(schema, [...(bySchema.get(schema) ?? []), part]);
  }
  for (const [schema, parts] of bySchema) failures.push(...validate(schema, 'xsd', parts));
  return failures;
}