"""HTTP OTA (SCP81 / GP RAM over HTTP) emulation.

Phase A: terminal-side BIP emulation (OPEN/SEND/RECEIVE/CLOSE CHANNEL) plus a
raw TCP capture listener. The card's BIP channel is always redirected to the
locally configured target (the future PSK TLS platform); the address the card
requested is only logged.

Reference behavior (TS 102 223 8.52-8.56, GP v2.2 Amendment B) is taken from
the captured real-terminal traces in samples/HTTP_OTA/traces:
  OPEN CHANNEL   TR: result, Channel status (38), Bearer description (35), Buffer size (39)
  SEND DATA      TR: result, Channel data length (37)
  RECEIVE DATA   TR: result, Channel data (36), Channel data length (37)
  CLOSE CHANNEL  TR: result
"""

import socket
import threading
import time

MAX_LOG = 1000


def ber_len_read(data, off):
    """Read a BER-TLV length at data[off]; returns (length, next_offset)."""
    if off >= len(data):
        return 0, off
    b = data[off]
    if b < 0x80:
        return b, off + 1
    n = b & 0x7F
    if n == 0 or off + 1 + n > len(data):
        return 0, len(data)
    return int.from_bytes(data[off + 1:off + 1 + n], 'big'), off + 1 + n


def proactive_tlvs(raw):
    """Top-level TLV map {tag: value} of a D0 proactive command."""
    out = {}
    if not raw or raw[0] != 0xD0:
        return out
    ln, off = ber_len_read(raw, 1)
    end = min(len(raw), off + ln)
    while off + 1 < end:
        tag = raw[off]
        tlen, off2 = ber_len_read(raw, off + 1)
        val = raw[off2:off2 + tlen]
        off = off2 + tlen
        out.setdefault(tag, val)
    return out


def parse_other_address(value):
    """Decode an 'Other address' TLV (21=IPv4, 57=IPv6, F0=FQDN)."""
    if not value:
        return None
    t = value[0]
    if t == 0x21 and len(value) >= 5:
        return '.'.join(str(b) for b in value[1:5])
    if t == 0x57 and len(value) >= 17:
        return ':'.join('%x' % int.from_bytes(value[i:i + 2], 'big') for i in range(1, 17, 2))
    if t == 0xF0:
        return value[1:].decode('ascii', 'replace')
    return None


def parse_transport_level(value):
    """Decode an UICC/terminal interface transport level TLV -> (proto, port)."""
    if not value or len(value) < 3:
        return None, None
    return value[0], int.from_bytes(value[1:3], 'big')


TAG_BEARER = 0x35
TAG_CHANNEL_DATA = 0x36
TAG_CHANNEL_DATA_LENGTH = 0x37
TAG_CHANNEL_STATUS = 0x38
TAG_BUFFER_SIZE = 0x39
TAG_TRANSPORT_LEVEL = 0x3C
TAG_OTHER_ADDRESS = 0x3E
TAG_NAA = 0x47


class BipChannel:
    def __init__(self, channel_id, sock, requested, target, buffer_size):
        self.id = channel_id
        self.sock = sock
        self.requested = requested
        self.target = target
        self.buffer_size = buffer_size or 512
        self.rx = bytearray()
        self.bytes_in = 0
        self.bytes_out = 0
        self.opened_at = time.time()
        self.peer_closed = False

    def pump(self, timeout=0.05):
        """Move whatever the network has into the local buffer. Returns bytes moved."""
        if self.peer_closed:
            return 0
        moved = 0
        self.sock.settimeout(timeout)
        try:
            while True:
                chunk = self.sock.recv(self.buffer_size)
                if not chunk:
                    self.peer_closed = True
                    break
                self.rx.extend(chunk)
                self.bytes_in += len(chunk)
                moved += len(chunk)
                if len(chunk) < self.buffer_size:
                    break
        except (socket.timeout, BlockingIOError):
            pass
        except OSError:
            self.peer_closed = True
        return moved

    def send(self, data):
        self.sock.sendall(data)
        self.bytes_out += len(data)

    def take(self, maxlen):
        self.pump()
        n = min(maxlen, len(self.rx), self.buffer_size)
        out = bytes(self.rx[:n])
        del self.rx[:n]
        return out

    def available(self):
        self.pump()
        return len(self.rx)

    def send_capacity(self):
        free = self.buffer_size - len(self.rx)
        return 0xFF if free > 0xFF else max(0, free)

    def close(self):
        try:
            self.sock.shutdown(socket.SHUT_RDWR)
        except OSError:
            pass
        try:
            self.sock.close()
        except OSError:
            pass


class BipTerminal:
    """Terminal (device) side of BIP: channels to the configured target."""

    def __init__(self):
        self.enabled = False
        self.target = None
        self.channels = {}
        self.next_id = 1
        self.entries = []
        self.seq = 0
        self.lock = threading.Lock()

    def log(self, kind, **fields):
        with self.lock:
            self.seq += 1
            entry = {'seq': self.seq, 't': time.time(), 'kind': kind}
            entry.update(fields)
            self.entries.append(entry)
            if len(self.entries) > MAX_LOG:
                del self.entries[:len(self.entries) - MAX_LOG]
            return entry

    def enable(self, host, port):
        self.target = (host, int(port))
        self.enabled = True
        self.log('enabled', target='%s:%d' % self.target)

    def disable(self):
        self.enabled = False
        self.log('disabled')
        self.close_all()
        self.target = None

    def close_all(self):
        for ch in list(self.channels.values()):
            self._close_channel(ch)

    def _close_channel(self, ch):
        ch.close()
        if self.channels.get(ch.id) is ch:
            del self.channels[ch.id]

    def _alloc_id(self):
        for _ in range(7):
            cid = self.next_id
            self.next_id = 1 if cid >= 7 else cid + 1
            if cid not in self.channels:
                return cid
        return None

    def open(self, requested_host, requested_port, buffer_size):
        """Open a channel to the redirect target. Returns (channel_id, error)."""
        if not self.enabled or not self.target:
            return None, 'bip disabled'
        target = self.target
        requested = '%s:%s' % (requested_host, requested_port)
        cid = self._alloc_id()
        if cid is None:
            self.log('open-fail', requested=requested, reason='no free channel')
            return None, 'no free channel'
        try:
            sock = socket.create_connection(target, timeout=2.0)
        except OSError as e:
            self.log('open-fail', requested=requested, target='%s:%d' % target, reason=str(e))
            return None, str(e)
        ch = BipChannel(cid, sock, requested, target, buffer_size)
        self.channels[cid] = ch
        self.log('open', channel=cid, requested=requested, target='%s:%d' % target,
                 buffer_size=ch.buffer_size)
        return cid, None

    def send(self, channel_id, data):
        ch = self.channels.get(channel_id)
        if not ch:
            return False
        try:
            ch.send(data)
        except OSError as e:
            self.log('send-fail', channel=channel_id, error=str(e))
            self._close_channel(ch)
            return False
        self.log('send', channel=channel_id, bytes=len(data), hex=data.hex().upper()[:2000])
        return True

    def receive(self, channel_id, maxlen):
        ch = self.channels.get(channel_id)
        if not ch:
            return None
        data = ch.take(maxlen)
        if data:
            self.log('receive', channel=channel_id, bytes=len(data), remaining=len(ch.rx),
                     hex=data.hex().upper()[:2000])
        return data

    def available(self, channel_id):
        ch = self.channels.get(channel_id)
        return ch.available() if ch else 0

    def send_capacity(self, channel_id):
        ch = self.channels.get(channel_id)
        return ch.send_capacity() if ch else 0

    def clear_log(self):
        with self.lock:
            self.entries = []

    def close(self, channel_id):
        ch = self.channels.get(channel_id)
        if not ch:
            return False
        self.log('close', channel=channel_id, bytes_in=ch.bytes_in, bytes_out=ch.bytes_out)
        self._close_channel(ch)
        return True

    def status(self):
        channels = []
        for ch in self.channels.values():
            channels.append({
                'id': ch.id,
                'requested': ch.requested,
                'target': '%s:%d' % ch.target,
                'buffer_size': ch.buffer_size,
                'bytes_in': ch.bytes_in,
                'bytes_out': ch.bytes_out,
                'pending': len(ch.rx),
                'peer_closed': ch.peer_closed,
            })
        return {
            'enabled': self.enabled,
            'target': '%s:%d' % self.target if self.target else None,
            'channels': channels,
            'seq': self.seq,
        }

    def entries_after(self, after=0):
        with self.lock:
            return [e for e in self.entries if e['seq'] > after]


class TcpDumpServer:
    """Plain TCP listener that logs whatever it receives (ClientHello capture).

    Used as the BIP redirect target until the PSK TLS platform is brought up.
    """

    def __init__(self, host, port, on_rx=None, on_log=None):
        self.on_rx = on_rx
        self.on_log = on_log
        self.stopped = False
        self.conns = []
        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.sock.bind((host, int(port)))
        self.sock.listen(4)
        self.host, self.port = self.sock.getsockname()[:2]
        self.thread = threading.Thread(target=self._accept_loop, daemon=True)
        self.thread.start()
        if self.on_log:
            self.on_log('listener-start', host=self.host, port=self.port)

    def _accept_loop(self):
        while not self.stopped:
            try:
                self.sock.settimeout(0.2)
                conn, addr = self.sock.accept()
            except socket.timeout:
                continue
            except OSError:
                break
            self.conns.append(conn)
            if self.on_log:
                self.on_log('conn', peer='%s:%d' % addr[:2])
            threading.Thread(target=self._conn_loop, args=(conn, addr), daemon=True).start()

    def _conn_loop(self, conn, addr):
        try:
            while not self.stopped:
                conn.settimeout(0.2)
                try:
                    data = conn.recv(4096)
                except socket.timeout:
                    continue
                except OSError:
                    break
                if not data:
                    break
                if self.on_rx:
                    self.on_rx('%s:%d' % addr[:2], data)
        finally:
            try:
                conn.close()
            except OSError:
                pass

    def stop(self):
        self.stopped = True
        if self.on_log:
            self.on_log('listener-stop', host=self.host, port=self.port)
        try:
            self.sock.close()
        except OSError:
            pass
        for conn in self.conns:
            try:
                conn.close()
            except OSError:
                pass
        self.conns = []