chore: import upstream snapshot with attribution

apps/sim/lib/pptx-renderer/parser/rel-parser.ts

@@ -0,0 +1,81 @@
+/**
+ * Parser for .rels (Relationship) XML files in OOXML packages.
+ * These files map relationship IDs (rId1, rId2, ...) to targets.
+ */
+
+import { parseXml } from './xml-parser'
+
+export interface RelEntry {
+  type: string
+  target: string
+  targetMode?: string
+}
+
+/**
+ * Parse a .rels XML string into a Map of relationship ID -> RelEntry.
+ *
+ * Example input:
+ * ```xml
+ * <Relationships xmlns="...">
+ *   <Relationship Id="rId1" Type="http://...slide" Target="slides/slide1.xml"/>
+ * </Relationships>
+ * ```
+ */
+export function parseRels(xmlString: string): Map<string, RelEntry> {
+  const result = new Map<string, RelEntry>()
+
+  if (!xmlString) return result
+
+  const root = parseXml(xmlString)
+  if (!root.exists()) return result
+
+  const relationships = root.children('Relationship')
+  for (const rel of relationships) {
+    const id = rel.attr('Id')
+    const type = rel.attr('Type')
+    const target = rel.attr('Target')
+    const targetMode = rel.attr('TargetMode')
+
+    if (id && type !== undefined && target !== undefined) {
+      result.set(id, { type, target, targetMode })
+    }
+  }
+
+  return result
+}
+
+/**
+ * Resolve a relative target path against a base path.
+ *
+ * Examples:
+ *   resolveRelTarget('ppt/slides', '../slideLayouts/slideLayout1.xml')
+ *     → 'ppt/slideLayouts/slideLayout1.xml'
+ *
+ *   resolveRelTarget('ppt/slides', 'media/image1.png')
+ *     → 'ppt/slides/media/image1.png'
+ *
+ *   resolveRelTarget('ppt', 'slides/slide1.xml')
+ *     → 'ppt/slides/slide1.xml'
+ */
+export function resolveRelTarget(basePath: string, target: string): string {
+  // Absolute targets (start with /) are returned as-is (strip leading /)
+  if (target.startsWith('/')) {
+    return target.slice(1)
+  }
+
+  // Split the base path into segments
+  const baseParts = basePath.replace(/\\/g, '/').split('/').filter(Boolean)
+  const targetParts = target.replace(/\\/g, '/').split('/').filter(Boolean)
+
+  // Walk through target parts, resolving '..' by popping base parts
+  const resolved = [...baseParts]
+  for (const part of targetParts) {
+    if (part === '..') {
+      resolved.pop()
+    } else if (part !== '.') {
+      resolved.push(part)
+    }
+  }
+
+  return resolved.join('/')
+}