AI

{
  "paragraphs": [
    {
      "text": "MuPDF minimizes global state by isolating context and document lifetimes.",
      "citations": [
        {
          "chunk_id": 12,
          "quote": "MuPDF has no global variables and therefore no hidden dependencies..."
        }
      ]
    }
  ]
}

async function highlightAnswerSources(webViewer, paragraphs) {
  // Reuse locateSource results when the same quote appears multiple times.
  const quoteCache = new Map()
  // Collect every rect first, then draw highlights in a single call.
  const highlightRects = []
  // Remember the first match so we can navigate users to it.
  let firstResolvedPage = null

  for (const paragraph of paragraphs) {
    const citations = Array.isArray(paragraph?.citations) ? paragraph.citations : []

    for (const citation of citations) {
      // Normalize AI output and skip empty/non-string-like quote values.
      const quote = String(citation?.quote ?? '').trim()
      if (!quote) {
        continue
      }

      let located = quoteCache.get(quote)
      if (located === undefined) {
        try {
          // Map a quote to page/word rectangles in the loaded PDF.
          located = await webViewer.text.locateSource({ text: quote })
        } catch {
          // Cache failures too, so repeated bad quotes do not re-query.
          located = null
        }
        quoteCache.set(quote, located)
      }

      // Ignore unresolved matches or unexpected result shapes.
      if (!located || !Array.isArray(located.words)) {
        continue
      }

      if (firstResolvedPage === null && Number.isFinite(located.pageIndex)) {
        firstResolvedPage = located.pageIndex
      }

      for (const word of located.words) {
        const rects = Array.isArray(word?.rects) ? word.rects : []
        for (const rect of rects) {
          highlightRects.push({
            color: '#ff00ff',
            pageIndex: located.pageIndex,
            rect,
          })
        }
      }
    }
  }

  if (highlightRects.length > 0) {
    // Batch highlight for better performance and fewer UI updates.
    await webViewer.viewer.highlight({ rects: highlightRects })
  }

  if (Number.isFinite(firstResolvedPage)) {
    // Move viewport to the first citation hit for immediate context.
    await webViewer.viewer.scrollTo({
      type: webViewer.refs.scroll.type.PAGE,
      value: firstResolvedPage,
    })
  }
}