#! /usr/bin/env python3
# SPDX-License-Identifier: BSD-3-Clause
# Copyright(c) 2020 Intel Corporation

"""
Script to be used with V2 Telemetry.
Allows the user input commands and read the Telemetry response.
"""

import socket
import os
import sys
import glob
import json
import errno
import readline
import argparse

# global vars
TELEMETRY_VERSION = "v2"
SOCKET_NAME = 'dpdk_telemetry.{}'.format(TELEMETRY_VERSION)
DEFAULT_PREFIX = 'rte'
CMDS = []


def read_socket(sock, buf_len, echo=True):
    """ Read data from socket and return it in JSON format """
    reply = sock.recv(buf_len).decode()
    try:
        ret = json.loads(reply)
    except json.JSONDecodeError:
        print("Error in reply: ", reply)
        sock.close()
        raise
    if echo:
        print(json.dumps(ret))
    return ret


def get_app_name(pid):
    """ return the app name for a given PID, for printing """
    proc_cmdline = os.path.join('/proc', str(pid), 'cmdline')
    try:
        with open(proc_cmdline) as f:
            argv0 = f.read(1024).split('\0')[0]
            return os.path.basename(argv0)
    except IOError as e:
        # ignore file not found errors
        if e.errno != errno.ENOENT:
            raise
    return None


def find_sockets(path):
    """ Find any possible sockets to connect to and return them """
    return glob.glob(os.path.join(path, SOCKET_NAME + '*'))


def print_socket_options(prefix, paths):
    """ Given a set of socket paths, give the commands needed to connect """
    cmd = sys.argv[0]
    if prefix != DEFAULT_PREFIX:
        cmd += " -f " + prefix
    for s in sorted(paths):
        sock_name = os.path.basename(s)
        if sock_name.endswith(TELEMETRY_VERSION):
            print("- {}  # Connect with '{}'".format(os.path.basename(s),
                                                     cmd))
        else:
            print("- {}  # Connect with '{} -i {}'".format(os.path.basename(s),
                                                           cmd,
                                                           s.split(':')[-1]))


def get_dpdk_runtime_dir(fp):
    """ Using the same logic as in DPDK's EAL, get the DPDK runtime directory
    based on the file-prefix and user """
    if (os.getuid() == 0):
        return os.path.join('/var/run/dpdk', fp)
    return os.path.join(os.environ.get('XDG_RUNTIME_DIR', '/tmp'), 'dpdk', fp)


def list_fp():
    """ List all available file-prefixes to user """
    path = get_dpdk_runtime_dir('')
    sockets = glob.glob(os.path.join(path, "*", SOCKET_NAME + "*"))
    prefixes = []
    if not sockets:
        print("No DPDK apps with telemetry enabled available")
    else:
        print("Valid file-prefixes:\n")
    for s in sockets:
        prefixes.append(os.path.relpath(os.path.dirname(s), start=path))
    for p in sorted(set(prefixes)):
        print(p)
        print_socket_options(p, glob.glob(os.path.join(path, p,
                                                       SOCKET_NAME + "*")))


def handle_socket(args, path):
    """ Connect to socket and handle user input """
    prompt = ''  # this evaluates to false in conditions
    sock = socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET)
    global CMDS

    if os.isatty(sys.stdin.fileno()):
        prompt = '--> '
        print("Connecting to " + path)
    try:
        sock.connect(path)
    except OSError:
        print("Error connecting to " + path)
        sock.close()
        # if socket exists but is bad, or if non-interactive just return
        if os.path.exists(path) or not prompt:
            return
        # if user didn't give a valid socket path, but there are
        # some sockets, help the user out by printing how to connect
        socks = find_sockets(os.path.dirname(path))
        if socks:
            print("\nOther DPDK telemetry sockets found:")
            print_socket_options(args.file_prefix, socks)
        else:
            list_fp()
        return
    json_reply = read_socket(sock, 1024, prompt)
    output_buf_len = json_reply["max_output_len"]
    app_name = get_app_name(json_reply["pid"])
    if app_name and prompt:
        print('Connected to application: "%s"' % app_name)

    # get list of commands for readline completion
    sock.send("/".encode())
    CMDS = read_socket(sock, output_buf_len, False)["/"]

    # interactive prompt
    try:
        text = input(prompt).strip()
        while text != "quit":
            if text.startswith('/'):
                sock.send(text.encode())
                read_socket(sock, output_buf_len)
            text = input(prompt).strip()
    except EOFError:
        pass
    finally:
        sock.close()


def readline_complete(text, state):
    """ Find any matching commands from the list based on user input """
    all_cmds = ['quit'] + CMDS
    if text:
        matches = [c for c in all_cmds if c.startswith(text)]
    else:
        matches = all_cmds
    return matches[state]


readline.parse_and_bind('tab: complete')
readline.set_completer(readline_complete)
readline.set_completer_delims(readline.get_completer_delims().replace('/', ''))

parser = argparse.ArgumentParser()
parser.add_argument('-f', '--file-prefix', default=DEFAULT_PREFIX,
                    help='Provide file-prefix for DPDK runtime directory')
parser.add_argument('-i', '--instance', default='0', type=int,
                    help='Provide instance number for DPDK application')
parser.add_argument('-l', '--list', action="store_true", default=False,
                    help='List all possible file-prefixes and exit')
args = parser.parse_args()
if args.list:
    list_fp()
    sys.exit(0)
sock_path = os.path.join(get_dpdk_runtime_dir(args.file_prefix), SOCKET_NAME)
if args.instance > 0:
    sock_path += ":{}".format(args.instance)
handle_socket(args, sock_path)