[NL77]

Hi,
I have several Indesign exports in which the authors’ names in the Index refer to page numbers.
Like this
First Author 18, 25.
Second Author 123, 259, 368. etc.

<p class="inp">First Author <a href="epi1.xhtml#idx104">18</a>, <a href="epi2.xhtml#idx624">23</a></p>
<p class="inp">Second Author <a href="epi1.xhtml#idx057">123</a>, <a href="epi1.xhtml#idx178">259</a>, <a href="epi1.xhtml#idx241">368</a></p>

I need to replace these page numbers in the e-book with ascending numbers.
Like this:
First Author 1, 2.
Second Author 1, 2, 3. etc.

<p class="inp">First Author <a href="epi1.xhtml#idx104">1</a>, <a href="epi2.xhtml#idx624">2</a></p>
<p class="inp">Second Autor <a href="epi1.xhtml#idx057">1</a>, <a href="epi1.xhtml#idx178">2</a>, <a href="epi1.xhtml#idx241">3</a></p>

I wrote a simple but working Python script which does the job:
It looks like this:

import re

i = 0

def IncrementalNumbers(m):
    global i
    i+=1
    return str(i)

PageNumbers = r'(\d+)(?=</a>)'

with open("index.xhtml", 'r') as fp, open("index_renumbered.xhtml","w") as out:
    # read only one line of the file and apply the transformations
    for line in fp:
        i = 0
        l = re.sub(PageNumbers, IncrementalNumbers, line)
        out.write(l)

It would be much faster if I could use this as a plugin, but unfortunately, I have never written a plugin before, and I don't have enough knowledge for it.
My first attempt was only half successful, because the plugin counts globally, not line by line.

import re
import sys
import sigil_bs4
from bs4 import BeautifulSoup

text_type = str

i = 0

def IncrementalNumbers(m):
    global i
    i+=1
    return str(i)

PageNumbers = r'(\d+)(?=</a>)'
#RefSymbol = '←'

def run(bk):
    for (id, href) in bk.text_iter():
        print('Start %s:' % href)
        html = bk.readfile(id)
        soup = sigil_bs4.BeautifulSoup(html)

    html_orig = html

    html = re.sub(PageNumbers, IncrementalNumbers, html)


    if not html == html_orig:
        print("Modified File --> ", id)
        bk.writefile(id, html)

    return 0


def main():
    print("I reached main when I should not have\n")
    return -1

if __name__ == "__main__":
    sys.exit(main())

This is the result: Second Author 3, 4, 5 instead of Second Author 1, 2, 3

<p class="inp">First Author <a href="epi1.xhtml#idx104">1</a>, <a href="epi2.xhtml#idx624">2</a></p>
<p class="inp">Second Autor <a href="epi1.xhtml#idx057">1</a>, <a href="epi1.xhtml#idx178">2</a>, <a href="epi1.xhtml#idx241">3</a></p>

Can someone help me to define the lines in the plugin?
Thank you