How to index document pages that can be retrieved later into elasticsearch

I am indexing PDF documents in elasticsearch without using the official plugin, I am using a PHP library to parse PDF content into plain text. This PHP library allows me to get the document content by pages so I would like my search page would retrieve some highlight similar to:

[Page 1] ... Highlighted text from the search ... [Page 4] ... Highlighted text from page 4 that match with the search ...

The mapping they gave to me is like this, I just converted text from string to array:

properties: {

    highlight:{

        text: [ "Page1Content...", "Page2Content...", "Page3Content...", ...],

        other_fields: {}

    },

    other_fields: {}
}

But I caot find a way to get the array indexes when getting the highlighted content, it get lost in the way.

Are nested / objects the only way to know the page number when I search? I don't know if array keys are lost when highlighting too. I thought in something like or similar:

highlight : {

    text: {
            "Page1" : "Page1Content",
            "Page2": "Page2Content",
            ....
          },
    other_fields: {}
}

Thanks in advance.