import cgi
import datetime
import hashlib
import re
import socket
import ssl
import time
import unicodedata
import urllib.parse as urlparse
from OpenSSL import crypto


UTC = datetime.timezone.utc

def _build_math_translation():
    table = {}
    for cp in range(0x1D400, 0x1D800):
        name = unicodedata.name(chr(cp), '')
        if name.startswith('MATHEMATICAL'):
            parts = name.split()
            letter = parts[-1]
            if len(letter) == 1 and letter.isalpha():
                table[cp] = letter.lower() if 'SMALL' in parts else letter
    return str.maketrans(table)

_MATH_TRANS = _build_math_translation()
GEMTEXT_MARKUP = re.compile(r'^(\s*=>\s*|\* |>\s*|##?#?)')
URI_PATTERN = re.compile(r'(gemini|finger|gopher|spartan|nex|guppy|mailto|data|file|https?|fdroidrepos?:):(//)?[^`") ]+(\s+—)?')
NONLINK_URI_PATTERN = re.compile(r'(?<!=>)(?<!=>\s)(gemini|finger|gopher|spartan|nex|guppy|mailto|data|file|https?|fdroidrepos?:):(//)?[^`")\s]+')
INNER_LINK_PREFIX = '— '


class GeminiError (Exception):
    def __init__(self, code, msg):
        super().__init__(msg)
        self.code = code


def unescape_ini_gemtext(src):
    unesc = []
    for line in src.split('\n'):
        line = line.strip()
        if line == '|':
            line = ''
        elif line.startswith('&&&'):
            line = '###' + line[3:]
        elif line.startswith('&&'):
            line = '##' + line[2:]
        elif line.startswith('&'):
            line = '#' + line[1:]
        unesc.append(line)
    return '\n'.join(unesc)


def is_valid_name(name):
    if len(name) < 2 or len(name) > 30:
        return False
    return re.match(r'^[\w-]+$', name) != None


def plural_s(i, suffix='s'):
    return '' if i == 1 else suffix


def plural(i, word, suffix='s'):
    return f'{i} {word}{plural_s(i, suffix)}'


def plural_form(i, singular, plural=None):
    if plural is None:
        plural = singular + 's'
    return f'{i} {singular if i == 1 else plural}'


def parse_at_names(text) -> list:
    names = set()
    pattern = re.compile(r'(\bu/|@)([\w-]+)')
    pos = 0
    while pos < len(text):
        found = pattern.search(text, pos)
        if not found: break
        names.add(found[2].lower())
        pos = found.end()
    return list(names)


def parse_likely_commit_hashes(text) -> list:
    hashes = set()
    pattern = re.compile(r'\b[0-9a-fA-F]{7,}\b')
    pos = 0
    while pos < len(text):
        found = pattern.search(text, pos)
        if not found: break
        hashes.add(found[0].lower())
        pos = found.end()
    return list(hashes)


def clean_text(text):
    text = strip_invalid(text)
    # Clean up the text: ensure that preformatted is closed.
    pre = False
    for line in text.split('\n'):
        if line[:3] == '```':
            pre = not pre
    if pre:
        # Close the preformatted block.
        if not text.endswith('\n'):
            text += '\n'
        text += '```'
    return text.rstrip()


def split_paragraphs(text) -> list:
    """Split paragraphs unless the empty lines are found inside a preformatted block."""
    paragraphs = []
    pre = False
    para = []
    start = 0
    empty_count = 0
    lines = text.split('\n')
    for i, line in enumerate(lines):
        if not pre:
            if len(line.strip()) == 0:
                empty_count += 1
                continue
            if empty_count >= 1:
                para = '\n'.join(lines[start:i]).strip()
                if len(para):
                    paragraphs.append(para)
                start = i
                empty_count = 0
        if line[:3] == '```':
            pre = not pre
    last = '\n'.join(lines[start:]).strip()
    if len(last):
        paragraphs.append(last)
    return paragraphs if len(paragraphs) > 0 else ['']


def remove_prefix(text, prefix):
    if text.startswith(prefix):
        return text[len(prefix):]
    return text


def strip_links(text, placeholder=True):
    return URI_PATTERN.sub(r'[\1 link]' if placeholder else '', text)


def parse_nonlink_uris(text) -> list:
    links = []
    pos = 0
    while pos < len(text):
        found = NONLINK_URI_PATTERN.search(text, pos)
        if not found: break
        links.append(found[0])
        pos = found.end()
    return links


def clean_unicode_math(text):
    """Replace Unicode mathematical A-Z letters (bold, italic, etc.) with plain ASCII."""
    return text.translate(_MATH_TRANS)


def clean_title(title):
    # Strip `=>` and other Gemini syntax.
    cleaned = []
    pre = False
    unlabeled_link_pattern = re.compile(r'(\w+://[^ ]+) — \1')
    for line in title.split('\n'):
        if line[:3] == '```':
            if not pre:
                pre_label = line[3:].strip()
                if len(pre_label) == 0:
                    pre_label = 'preformatted'
                line = f'[{pre_label}]'
                cleaned.append(line)
            pre = not pre
            continue
        if pre:
            continue
        found = GEMTEXT_MARKUP.match(line)
        if found:
            line = line[found.end():]
        line = unlabeled_link_pattern.sub(r'\1', line)
        line = line.replace('\t', ' ').replace('\r', '')
        cleaned.append(line)
    title = ' '.join(cleaned).strip()
    return clean_unicode_math(title)


def clean_description(desc):
    # Strip links but keep other formatting.
    cleaned = []
    pre = False
    for line in desc.split('\n'):
        line = line.strip()
        if line.startswith('```'):
            pre = not pre
        if not pre:
            if line.startswith('=>'):
                continue
        cleaned.append(line)
    return '\n'.join(cleaned)


def clean_tinylog(text):
    # Clean it up as per Tinylog specification.
    clean = []
    pre = False
    for line in text.split('\n'):
        if line.startswith('```'):
            clean.append(line)
            pre = not pre
            continue
        if pre:
            clean.append(line)
            continue
        m = re.search(r'^(##?)[^#]', line) # only level 3 headings allowed
        if m:
            line = '###' + line[len(m[1]):]
        clean.append(line)
    return '\n'.join(clean)


def prefix_links(src, prefix):
    """Add a prefix to link labels."""
    if not prefix:
        return src
    lines = []
    pattern = re.compile(r'^\s*=>\s*([^ ]+)(\s+(.*))?$')
    pre = False
    for line in src.split('\n'):
        if line.startswith('```'):
            pre = not pre
        elif not pre:
            m = pattern.match(line)
            if m:
                label = m[3].strip() if m[3] and len(m[3]) else ''
                if len(label) == 0:
                    label = m[1]
                    # Omit gemini scheme.
                    if label.startswith('gemini://'):
                        label = label[9:]
                line = f'=> {m[1]} {prefix}{label}'
        lines.append(line)
    return '\n'.join(lines)


def strip_multibreaks(src):
    lines = []
    pre = False
    last_was_break = False
    for line in src.split('\n'):
        if line.startswith('```'):
            pre = not pre
            is_break = False
        elif not pre:
            is_break = len(line.strip()) == 0
            if is_break and last_was_break:
                continue
            last_was_break = is_break
        lines.append(line)
    return '\n'.join(lines)


def strip_invalid(src):
    return src.replace('\x00', '').replace('\r', '')


def shorten_text(text, n):
    """Truncate and cut at white or word boundary."""
    if len(text) > n:
        text = text[:n]
        if text[-1] == ' ':
            return text.strip() + '…'
        m = re.search(r'[\w,.]+$', text)
        if m:
            return text[:m.start()].rstrip() + '…'
        return text.rstrip() + '…'
    return text.strip()


def extract_title_heading(session, body):
    lines = body.split('\n')
    title = None
    found = re.match(r'^\s*#\s*(.+)$', lines[0])
    foundH2 = re.match(r'^\s*##\s*(.+)$', lines[0])
    if found and not foundH2:
        title = found[1]
        body = '\n'.join(lines[1:]).strip()
    elif session.is_context_tracker:
        title = lines[0]
        body = '\n'.join(lines[1:]).strip()
    return title, body


def time_delta_text(sec, date_ts, suffix='ago', now='Now',
                    date_prefix='',
                    date_fmt='%Y-%m-%d',
                    date_sep=' · ',
                    short_date_fmt='%b %d',
                    tz=None):
    if sec < 2:
        return now
    if sec < 60:
        return f'{sec} seconds {suffix}'
    mins = int(sec / 60)
    if sec < 3600:
        return f'{mins} minute{plural_s(mins)} {suffix}'
    hours = int(sec / 3600)
    if hours <= 24:
        return f'{hours} hour{plural_s(hours)} {suffix}'
    days = round(sec / 3600 / 24)
    dt = datetime.datetime.fromtimestamp(date_ts, UTC)
    if tz:
        dt = dt.astimezone(tz)
    current_year = datetime.datetime.now().year
    age = date_prefix + dt.strftime(short_date_fmt if dt.year == current_year else date_fmt)
    if days < 14:
        return age + f'{date_sep}{days} day{plural_s(days)} {suffix}'
    weeks = round(days / 7)
    if weeks <= 8:
        return age + f'{date_sep}{weeks} week{plural_s(weeks)} {suffix}'
    months = round(days / (365 / 12)) # average month length
    if months < 12:
        return age + f'{date_sep}{months} month{plural_s(months)} {suffix}'
    years = round(days / 365)
    return age + f'{date_sep}{years} year{plural_s(years)} {suffix}'


def ago_text(ts, suffix='ago', now='Now', tz=None):
    sec = max(0, int(time.time()) - ts)
    return time_delta_text(sec, ts, suffix, now, tz=tz)


def atom_timestamp(ts):
    return datetime.datetime.fromtimestamp(ts, UTC).strftime("%Y-%m-%dT%H:%M:%SZ")


def atom_escaped(text):
    return text.replace('&', '&amp;').replace('<', '&lt;').replace('>', '&gt;').\
        replace("'", '&apos;').replace('"', '&quot;')


def gemtext_to_html(src):
    out = []

    in_list = False
    in_quote = False
    in_pre = False

    for line in src.rstrip().split('\n'):
        rend = None
        is_bullet = False
        is_angle = False
        if in_pre:
            if line.startswith('```'):
                in_pre = False
                rend = '</pre>'
            else:
                rend = atom_escaped(line)
        else:
            if line.startswith('###'):
                rend = f'<h3>{atom_escaped(line[3:].strip())}</h3>'
            elif line.startswith('##'):
                rend = f'<h2>{atom_escaped(line[2:].strip())}</h2>'
            elif line.startswith('#'):
                rend = f'<h1>{atom_escaped(line[1:].strip())}</h1>'
            elif line.startswith('>'):
                is_angle = True
                #if not in_quote:
                #    in_quote = True
                #    out.append('<blockquote>')
                rend = f'{atom_escaped(line[1:])}'
            elif line.startswith('*'):
                is_bullet = True
                #if not in_list:
                #    in_list = True
                #    out.append('<ul>')
                rend = f'<li>{atom_escaped(line[1:].strip())}</li>'
            elif line.startswith('=>'):
                link = re.match(r'=>\s*([^\s]+)(\s+.*)?', line)
                if not link:
                    continue
                url = link.group(1)
                label = link.group(2)
                if label is None:
                    label = url
                label = label.strip()
                parts = urlparse.urlparse(url)
                scheme = parts.scheme if parts.scheme else 'gemini'
                # if not parts.netloc:
                #   # Do something about a relative URL?
                link_attr = ''
                #if parts.path.endswith('.png') or parts.path.endswith('.jpg') or \
                #   parts.path.endswith('.webp'):
                #    # Render as an image.
                #    rend = f'<img src="{url}" title="{html_encode(label)}">'
                #else:
                rend = f'<p><a href="{url}">{atom_escaped(label)}</a></p>'
            elif line.startswith('```'):
                in_pre = True
                rend = '<pre>'
            else:
                rend = f'<p>{atom_escaped(line)}</p>'

        if rend is not None:
            if not is_bullet and in_list:
                out.append('</ul>')
                in_list = False
            if not is_angle and in_quote:
                out.append('</blockquote>')
                in_quote = False
            if is_angle and not in_quote:
                out.append('<blockquote>')
                in_quote = True
            if is_bullet and not in_list:
                out.append('<ul>')
                in_list = True
            out.append(rend)

    return '\n'.join(out)


def is_empty_query(req):
    return req.query == None or len(req.query) == 0


def clean_query(req):
    if req.query == None: return ''
    return clean_text(urlparse.unquote(req.query)).strip()


def nonzero(value):
    return 1 if value else 0


def is_zero(value):
    return 0 if value else 1


def parse_link_segment(content, unquote=True) -> tuple:
    if unquote:
        content = urlparse.unquote(content)
    q = content.replace('\n', ' ')
    found = re.match(r'^\s*(=>)?\s*([^\s]+)(\s+(.+))?\s*$', q)
    if not found:
        raise GeminiError(59, 'Invalid link syntax (enter URL followed by label, separated with space)')
    seg_url = found.group(2)
    if '://' not in seg_url:
        seg_url = 'gemini://' + seg_url
    parsed = urlparse.urlparse(seg_url)
    if not parsed.scheme or not parsed.netloc:
        raise GeminiError(59, 'Invalid URL')
    if found[4]:
        seg_text = clean_title(found[4])
    else:
        seg_text = ''
    return seg_url, seg_text


def parse_link_segment_query(req) -> tuple:
    if req.query == None:
        return '', ''
    return parse_link_segment(req.query)


def form_link(url_label: tuple):
    url, label = url_label
    if len(url) and len(label):
        return url + ' ' + label
    if len(label) == 0:
        return url
    return ''


def absolute_url(base, relative):
    # This is straight from Solderpunk's gemini-demo.py.
    if "://" not in relative:
        # Python's URL tools somehow only work with known schemes?
        base = base.replace("gemini://", "http://")
        relative = urlparse.urljoin(base, relative)
        relative = relative.replace("http://", "gemini://")
    # Remove the default port.
    port_pos = relative.find(':1965/')
    if port_pos >= 10:
        relative = relative[:port_pos] + relative[port_pos + 5:]
    return relative


def gemini_fetch(url, redirect_count=0, max_data=None) -> tuple:
    """Returns tuple: (mime, mime_params, body)."""

    if redirect_count == 5:
        raise Exception("Too many redirects")
    parts = urlparse.urlparse(url)
    if parts.scheme != 'gemini':
        raise Exception("Only Gemini URLs allowed")
    try:
        s = socket.create_connection((parts.hostname, parts.port if parts.port else 1965),
                                      timeout=10)
        context = ssl.SSLContext()
        context.check_hostname = False
        context.verify_mode = ssl.CERT_NONE
        s = context.wrap_socket(s, server_hostname=parts.hostname)
        s.sendall((url + '\r\n').encode("UTF-8"))
        got_header = False
        incoming = bytes()
        mime = 'application/octet-stream'

        while True:
            data = s.recv(4096 if not max_data else max(max_data, 1024))
            incoming += data

            if got_header and max_data and len(incoming) > max_data:
                #return mime, incoming
                break

            if not got_header:
                header_end = incoming.find(b'\r\n')
                if header_end > 0:
                    got_header = True
                    header = incoming[:header_end].decode("UTF-8").strip()
                    incoming = incoming[header_end + 2:]
                    parts = header.split()
                    status = parts[0]
                    mime = ''.join(parts[1:])

                    # Follow redirects.
                    if status.startswith('3'):
                        s.close()
                        del s
                        return gemini_fetch(absolute_url(url, mime),
                                            redirect_count=redirect_count + 1)

                    elif status.startswith('2'):
                        mime, mime_opts = cgi.parse_header(mime)

                    else:
                        print(url, 'gemini_fetch error:', header)
                        return None, None, None

            if len(data) == 0:
                break

        s.close()

        if got_header:
            if mime.startswith('text/'):
                return mime, mime_opts, incoming.decode(mime_opts.get("charset", "UTF-8"))
            else:
                return mime, mime_opts, incoming

    except Exception as er:
        print(str(er), '-- failed:', url)

    return None, None, None


def certificate_sha256(cert):
    der = crypto.dump_certificate(crypto.FILETYPE_ASN1, cert)
    m = hashlib.sha256()
    m.update(der)
    return m.hexdigest()


def pubkey_sha256(cert):
    pubkey = crypto.dump_publickey(crypto.FILETYPE_ASN1, cert.get_pubkey())
    m = hashlib.sha256()
    m.update(pubkey)
    return m.hexdigest()