#!/usr/bin/env python3

# Copyright (c) 2024 Project CHIP Authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import asyncio
import contextlib
import os
import shutil
import signal
import sys
import typing
from argparse import ArgumentParser
from tempfile import TemporaryDirectory


async def forward_f(prefix: bytes, f_in: asyncio.StreamReader,
                    f_out: typing.BinaryIO, cb=None):
    """Forward f_in to f_out with a prefix attached.

    This function can optionally feed received lines to a callback function.
    """
    while True:
        line = await f_in.readline()
        if not line:
            break
        if cb is not None:
            cb(line)
        f_out.buffer.write(prefix)
        f_out.buffer.write(line)
        f_out.flush()


async def forward_pipe(pipe_path: str, f_out: asyncio.StreamWriter):
    """Forward named pipe to f_out.

    Unfortunately, Python does not support async file I/O on named pipes. This
    function performs busy waiting with a short asyncio-friendly sleep to read
    from the pipe.
    """
    fd = os.open(pipe_path, os.O_RDONLY | os.O_NONBLOCK)
    while True:
        try:
            data = os.read(fd, 1024)
            if data:
                f_out.write(data)
                await f_out.drain()
            if not data:
                await asyncio.sleep(0.1)
        except BlockingIOError:
            await asyncio.sleep(0.1)


async def forward_stdin(f_out: asyncio.StreamWriter):
    """Forward stdin to f_out."""
    loop = asyncio.get_event_loop()
    reader = asyncio.StreamReader()
    protocol = asyncio.StreamReaderProtocol(reader)
    await loop.connect_read_pipe(lambda: protocol, sys.stdin)
    while True:
        line = await reader.readline()
        if not line:
            # Exit on Ctrl-D (EOF).
            sys.exit(0)
        f_out.write(line)
        await f_out.drain()


class Subprocess:

    def __init__(self, tag: str, program: str, *args, stdout_cb=None):
        self.event = asyncio.Event()
        self.tag = tag.encode()
        self.program = program
        self.args = args
        self.stdout_cb = stdout_cb
        self.expected_output = None

    def _check_output(self, line: bytes):
        if self.expected_output is not None and self.expected_output in line:
            self.event.set()

    async def run(self):
        self.p = await asyncio.create_subprocess_exec(self.program, *self.args,
                                                      stdin=asyncio.subprocess.PIPE,
                                                      stdout=asyncio.subprocess.PIPE,
                                                      stderr=asyncio.subprocess.PIPE)
        # Add the stdout and stderr processing to the event loop.
        asyncio.create_task(forward_f(self.tag, self.p.stderr, sys.stderr))
        asyncio.create_task(forward_f(self.tag, self.p.stdout, sys.stdout,
                                      cb=self._check_output))

    async def send(self, message: str, expected_output: str = None, timeout: float = None):
        """Send a message to a process and optionally wait for a response."""

        if expected_output is not None:
            self.expected_output = expected_output.encode()
            self.event.clear()

        self.p.stdin.write((message + "\n").encode())
        await self.p.stdin.drain()

        if expected_output is not None:
            await asyncio.wait_for(self.event.wait(), timeout=timeout)
            self.expected_output = None

    async def wait(self):
        await self.p.wait()

    def terminate(self):
        self.p.terminate()


async def run_admin(program, stdout_cb=None, storage_dir=None,
                    rpc_admin_port=None, rpc_bridge_port=None,
                    paa_trust_store_path=None, commissioner_name=None,
                    commissioner_node_id=None, commissioner_vendor_id=None):
    args = []
    if storage_dir is not None:
        args.extend(["--storage-directory", storage_dir])
    if rpc_admin_port is not None:
        args.extend(["--local-server-port", str(rpc_admin_port)])
    if rpc_bridge_port is not None:
        args.extend(["--fabric-bridge-server-port", str(rpc_bridge_port)])
    if paa_trust_store_path is not None:
        args.extend(["--paa-trust-store-path", paa_trust_store_path])
    if commissioner_name is not None:
        args.extend(["--commissioner-name", commissioner_name])
    if commissioner_node_id is not None:
        args.extend(["--commissioner-nodeid", str(commissioner_node_id)])
    if commissioner_vendor_id is not None:
        args.extend(["--commissioner-vendor-id", str(commissioner_vendor_id)])
    p = Subprocess("[FS-ADMIN]", program, "interactive", "start", *args,
                   stdout_cb=stdout_cb)
    await p.run()
    return p


async def run_bridge(program, storage_dir=None, rpc_admin_port=None,
                     rpc_bridge_port=None, discriminator=None, passcode=None,
                     secured_device_port=None):
    args = []
    if storage_dir is not None:
        args.extend(["--KVS",
                     os.path.join(storage_dir, "chip_fabric_bridge_kvs")])
    if rpc_admin_port is not None:
        args.extend(["--fabric-admin-server-port", str(rpc_admin_port)])
    if rpc_bridge_port is not None:
        args.extend(["--local-server-port", str(rpc_bridge_port)])
    if discriminator is not None:
        args.extend(["--discriminator", str(discriminator)])
    if passcode is not None:
        args.extend(["--passcode", str(passcode)])
    if secured_device_port is not None:
        args.extend(["--secured-device-port", str(secured_device_port)])
    p = Subprocess("[FS-BRIDGE]", program, *args)
    await p.run()
    return p


async def main(args):

    # Node ID of the bridge on the fabric.
    bridge_node_id = 1

    if args.commissioner_node_id == bridge_node_id:
        raise ValueError(f"NodeID={bridge_node_id} is reserved for the local fabric-bridge")

    storage_dir = args.storage_dir
    if storage_dir is not None:
        os.makedirs(storage_dir, exist_ok=True)
    else:
        storage = TemporaryDirectory(prefix="fabric-sync-app")
        storage_dir = storage.name

    pipe = args.stdin_pipe
    if pipe and not os.path.exists(pipe):
        os.mkfifo(pipe)

    admin, bridge = await asyncio.gather(
        run_admin(
            args.app_admin,
            storage_dir=storage_dir,
            rpc_admin_port=args.app_admin_rpc_port,
            rpc_bridge_port=args.app_bridge_rpc_port,
            paa_trust_store_path=args.paa_trust_store_path,
            commissioner_name=args.commissioner_name,
            commissioner_node_id=args.commissioner_node_id,
            commissioner_vendor_id=args.commissioner_vendor_id,
        ),
        run_bridge(
            args.app_bridge,
            storage_dir=storage_dir,
            rpc_admin_port=args.app_admin_rpc_port,
            rpc_bridge_port=args.app_bridge_rpc_port,
            secured_device_port=args.secured_device_port,
            discriminator=args.discriminator,
            passcode=args.passcode,
        ))

    def terminate():
        admin.terminate()
        bridge.terminate()
        sys.exit(0)

    loop = asyncio.get_event_loop()
    loop.add_signal_handler(signal.SIGINT, terminate)
    loop.add_signal_handler(signal.SIGTERM, terminate)

    # Wait a bit for apps to start.
    await asyncio.sleep(1)

    try:
        # Check whether the bridge is already commissioned. If it is,
        # we will get the response, otherwise we will hit timeout.
        await admin.send(
            f"descriptor read device-type-list {bridge_node_id} 1 --timeout 1",
            # Log message which should appear in the fabric-admin output if
            # the bridge is already commissioned.
            expected_output="Reading attribute: Cluster=0x0000_001D Endpoint=0x1 AttributeId=0x0000_0000",
            timeout=1.5)
    except asyncio.TimeoutError:
        # Commission the bridge to the admin.
        cmd = f"fabricsync add-local-bridge {bridge_node_id}"
        if args.passcode is not None:
            cmd += f" --setup-pin-code {args.passcode}"
        if args.secured_device_port is not None:
            cmd += f" --local-port {args.secured_device_port}"
        await admin.send(
            cmd,
            # Wait for the log message indicating that the bridge has been
            # added to the fabric.
            f"Commissioning complete for node ID {bridge_node_id:#018x}: success")

    # Open commissioning window with original setup code for the bridge.
    cw_endpoint_id = 0
    cw_option = 0  # 0: Original setup code, 1: New setup code
    cw_timeout = 600
    cw_iteration = 1000
    cw_discriminator = 0
    await admin.send(f"pairing open-commissioning-window {bridge_node_id} {cw_endpoint_id}"
                     f" {cw_option} {cw_timeout} {cw_iteration} {cw_discriminator}")

    try:
        await asyncio.gather(
            forward_pipe(pipe, admin.p.stdin) if pipe else forward_stdin(admin.p.stdin),
            admin.wait(),
            bridge.wait(),
        )
    except SystemExit:
        admin.terminate()
        bridge.terminate()
    except Exception:
        admin.terminate()
        bridge.terminate()
        raise


if __name__ == "__main__":
    parser = ArgumentParser(description="Fabric-Sync Example Application")
    parser.add_argument("--app-admin", metavar="PATH",
                        default=shutil.which("fabric-admin"),
                        help="path to the fabric-admin executable; default=%(default)s")
    parser.add_argument("--app-bridge", metavar="PATH",
                        default=shutil.which("fabric-bridge-app"),
                        help="path to the fabric-bridge executable; default=%(default)s")
    parser.add_argument("--app-admin-rpc-port", metavar="PORT", type=int,
                        help="fabric-admin RPC server port")
    parser.add_argument("--app-bridge-rpc-port", metavar="PORT", type=int,
                        help="fabric-bridge RPC server port")
    parser.add_argument("--stdin-pipe", metavar="PATH",
                        help="read input from a named pipe instead of stdin")
    parser.add_argument("--storage-dir", metavar="PATH",
                        help=("directory to place storage files in; by default "
                              "volatile storage is used"))
    parser.add_argument("--paa-trust-store-path", metavar="PATH",
                        help="path to directory holding PAA certificates")
    parser.add_argument("--commissioner-name", metavar="NAME",
                        help="commissioner name to use for the admin")
    parser.add_argument("--commissioner-node-id", metavar="NUM", type=int,
                        help="commissioner node ID to use for the admin")
    parser.add_argument("--commissioner-vendor-id", metavar="NUM", type=int,
                        help="commissioner vendor ID to use for the admin")
    parser.add_argument("--secured-device-port", metavar="NUM", type=int,
                        help="secure messages listen port to use for the bridge")
    parser.add_argument("--discriminator", metavar="NUM", type=int,
                        help="discriminator to use for the bridge")
    parser.add_argument("--passcode", metavar="NUM", type=int,
                        help="passcode to use for the bridge")
    args = parser.parse_args()
    if args.app_admin is None or not os.path.exists(args.app_admin):
        parser.error("fabric-admin executable not found in PATH. Use '--app-admin' argument to provide it.")
    if args.app_bridge is None or not os.path.exists(args.app_bridge):
        parser.error("fabric-bridge-app executable not found in PATH. Use '--app-bridge' argument to provide it.")
    with contextlib.suppress(KeyboardInterrupt):
        asyncio.run(main(args))