Find and replace in string re.insensitive

Question

I have this code to find matches in a string, im using in a search to mark the wordds that match my search, i need this to be case insensitive, the issue here is that it replaces the word by the one we search.

val_to_searchp = "this Text string has alot of teXt"
word = "TEXT"
    
pal2rep = str(":::")+word+str(":::")
val_to_search = re.sub(re.escape(word), pal2rep, val_to_searchp, flags=re.IGNORECASE)

this will return

"this :::TEXT::: string has alot of :::TEXT:::"

I need it to return

"this :::Text::: string has alot of :::teXt:::"

Also tryed with this but its not working very well :(

f = 0
s = 0
val_to_search = val_to_searchp
for m in re.finditer(str(word), str(val_to_searchp)):
      inicio = int(m.start()+s)
      fim = int(m.end()+f)
                
      val_to_search = val_to_search[:inicio] \
             + str(":::") \
             + val_to_search[inicio:fim] \
             + str(":::") \
             + val_to_search[fim:].strip()

      f = f+2
      s = s+1

This is my actuall code

def findtext():
    if len(str(findtext_inp.get('1.0', END)))>1:
        val_to_searchp = str(respon_txt.get(1.0, END).replace(html.unescape('⛔'), "").strip())
        respon_txt.delete(1.0, END)
        word = str(findtext_inp.get('1.0', END).strip())

        pal2rep = str(str(html.unescape('⛔'))+word+str(html.unescape('⛔')))
        val_to_search = re.sub(re.escape(word), pal2rep, val_to_searchp, flags=re.IGNORECASE)


        """
        f = 0
        s = 0
        for m in re.finditer(str(word), str(val_to_search)):
            inicio = int(m.start()+s)
            fim = int(m.end()+f)
        
            val_to_search = val_to_search[:inicio] \
                + str(html.unescape('⛔')) \
                + val_to_search[inicio:fim] \
                + str(html.unescape('⛔')) \
                + val_to_search[fim:].strip()

            f = f+2
            s = s+1
        """


    respon_txt.insert(1.0, val_to_search)#val_to_search.replace(findtext_inp.get('1.0', END).strip() , str(html.unescape('⛔')+findtext_inp.get('1.0', END).strip())+html.unescape('⛔')))

Answer 1

This is a rewrite of my original answer. In the comments for that answer you will see that the OP has changed his mind about how this needs to work. This now (hopefully) complies with the altered specification:

val_to_searchp = '''{\"configurationKey\":[{\"key\":\"GetMaxKeys\",\"readonly\":true,\"value\":\"20\"}'''
text = 'GetMaxKeys'

def func(s, txt):
    result = []
    sl = s.lower()
    txt = txt.lower()
    lt = len(txt)
    offset = 0
    while (i := sl[offset:].find(txt)) >= 0:
        result.append(s[offset:i+offset])
        offset += i
        result.append(f':::{s[offset:offset+lt]}:::')
        offset += lt
    result.append(s[offset:])
    return ''.join(result)

print(func(val_to_searchp, text))

Output:

{"configurationKey":[{"key":":::GetMaxKeys:::","readonly":true,"value":"20"}

Answer 2

I'm sure there's a way to do this with RE but it's really trivial without the aid of that module.

val_to_searchp = "this Text string has alot of teXt\nThis also has a lot of text"
text = 'TEXT'

def func(s, txt):
    txt = txt.lower()
    result = []
    for line in s.split('\n'):
        for i, e in enumerate(t := line.split()):
            if e.lower() == txt:
                t[i] = f':::{e}:::'
        result.append(' '.join(t))
    return '\n'.join(result)

print(func(val_to_searchp, text))

Output:

this :::Text::: string has alot of :::teXt:::
This also has a lot of :::text:::