text to url - converting to <img> and <a> tag in html

linkify.py

def linkify(html):
    check = ['https://', 'http://', 'www.', '.jpg', '.png', '.jpeg', '.gif']
    html_source = html
    replace = {}
    text = []
    for letter in html:
        if letter == '>':
            start = True
            continue
        elif letter == '<':
            start = False
            full_text = ''.join(text)
            full_text = full_text.replace('\n', '').strip()

            if '//' == full_text[:2]:
                full_text = full_text[2:]

            total = len(full_text)

            if full_text and total:

                if any(n in full_text for n in check)and total > 4:

                    if any(n in full_text[-4:] for n in ['.jpg', '.png', '.jpeg', '.gif']):
                        image_tag = '<img src={} height="150" width="150"></img>'.format(full_text)
                        replace[full_text] = image_tag

                    elif total > 9 and any(n in full_text[:9] for n in ['https://', 'http://', 'www.']):
                        if 'www' == full_text[:3]:
                            change_text = 'http://' + full_text
                            anchor_tag = '<a href="{}">{}</a>'.format(change_text, full_text)
                        else:
                            anchor_tag = '<a href="{}">{}</a>'.format(full_text, full_text)
                        replace[full_text] = anchor_tag
                    else:
                        print(full_text)

            text = []

        if start:
            text.append(letter)

    for key in replace:
        html_source = html_source.replace(key+'<', replace[key]+'<')
    return html_source