#!/usr/bin/env python
# Copyright 2021 The Matrix.org Foundation C.I.C.
#
# 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.

# This script reads environment variables and generates a shared Synapse worker,
# nginx and supervisord configs depending on the workers requested.
#
# The environment variables it reads are:
#   * SYNAPSE_SERVER_NAME: The desired server_name of the homeserver.
#   * SYNAPSE_REPORT_STATS: Whether to report stats.
#   * SYNAPSE_WORKER_TYPES: A comma separated list of worker names as specified in WORKER_CONFIG
#         below. Leave empty for no workers, or set to '*' for all possible workers.
#   * SYNAPSE_AS_REGISTRATION_DIR: If specified, a directory in which .yaml and .yml files
#         will be treated as Application Service registration files.
#   * SYNAPSE_TLS_CERT: Path to a TLS certificate in PEM format.
#   * SYNAPSE_TLS_KEY: Path to a TLS key. If this and SYNAPSE_TLS_CERT are specified,
#         Nginx will be configured to serve TLS on port 8448.
#
# NOTE: According to Complement's ENTRYPOINT expectations for a homeserver image (as defined
# in the project's README), this script may be run multiple times, and functionality should
# continue to work if so.

import os
import subprocess
import sys
from pathlib import Path
from typing import Any, Dict, List, Mapping, MutableMapping, NoReturn, Set

import yaml
from jinja2 import Environment, FileSystemLoader

MAIN_PROCESS_HTTP_LISTENER_PORT = 8080


WORKERS_CONFIG: Dict[str, Dict[str, Any]] = {
    "pusher": {
        "app": "synapse.app.pusher",
        "listener_resources": [],
        "endpoint_patterns": [],
        "shared_extra_conf": {"start_pushers": False},
        "worker_extra_conf": "",
    },
    "user_dir": {
        "app": "synapse.app.generic_worker",
        "listener_resources": ["client"],
        "endpoint_patterns": [
            "^/_matrix/client/(api/v1|r0|v3|unstable)/user_directory/search$"
        ],
        "shared_extra_conf": {"update_user_directory_from_worker": "user_dir1"},
        "worker_extra_conf": "",
    },
    "media_repository": {
        "app": "synapse.app.media_repository",
        "listener_resources": ["media"],
        "endpoint_patterns": [
            "^/_matrix/media/",
            "^/_synapse/admin/v1/purge_media_cache$",
            "^/_synapse/admin/v1/room/.*/media.*$",
            "^/_synapse/admin/v1/user/.*/media.*$",
            "^/_synapse/admin/v1/media/.*$",
            "^/_synapse/admin/v1/quarantine_media/.*$",
        ],
        "shared_extra_conf": {"enable_media_repo": False},
        "worker_extra_conf": "enable_media_repo: true",
    },
    "appservice": {
        "app": "synapse.app.generic_worker",
        "listener_resources": [],
        "endpoint_patterns": [],
        "shared_extra_conf": {"notify_appservices_from_worker": "appservice1"},
        "worker_extra_conf": "",
    },
    "federation_sender": {
        "app": "synapse.app.federation_sender",
        "listener_resources": [],
        "endpoint_patterns": [],
        "shared_extra_conf": {"send_federation": False},
        "worker_extra_conf": "",
    },
    "synchrotron": {
        "app": "synapse.app.generic_worker",
        "listener_resources": ["client"],
        "endpoint_patterns": [
            "^/_matrix/client/(v2_alpha|r0|v3)/sync$",
            "^/_matrix/client/(api/v1|v2_alpha|r0|v3)/events$",
            "^/_matrix/client/(api/v1|r0|v3)/initialSync$",
            "^/_matrix/client/(api/v1|r0|v3)/rooms/[^/]+/initialSync$",
        ],
        "shared_extra_conf": {},
        "worker_extra_conf": "",
    },
    "federation_reader": {
        "app": "synapse.app.generic_worker",
        "listener_resources": ["federation"],
        "endpoint_patterns": [
            "^/_matrix/federation/(v1|v2)/event/",
            "^/_matrix/federation/(v1|v2)/state/",
            "^/_matrix/federation/(v1|v2)/state_ids/",
            "^/_matrix/federation/(v1|v2)/backfill/",
            "^/_matrix/federation/(v1|v2)/get_missing_events/",
            "^/_matrix/federation/(v1|v2)/publicRooms",
            "^/_matrix/federation/(v1|v2)/query/",
            "^/_matrix/federation/(v1|v2)/make_join/",
            "^/_matrix/federation/(v1|v2)/make_leave/",
            "^/_matrix/federation/(v1|v2)/send_join/",
            "^/_matrix/federation/(v1|v2)/send_leave/",
            "^/_matrix/federation/(v1|v2)/invite/",
            "^/_matrix/federation/(v1|v2)/query_auth/",
            "^/_matrix/federation/(v1|v2)/event_auth/",
            "^/_matrix/federation/(v1|v2)/exchange_third_party_invite/",
            "^/_matrix/federation/(v1|v2)/user/devices/",
            "^/_matrix/federation/(v1|v2)/get_groups_publicised$",
            "^/_matrix/key/v2/query",
        ],
        "shared_extra_conf": {},
        "worker_extra_conf": "",
    },
    "federation_inbound": {
        "app": "synapse.app.generic_worker",
        "listener_resources": ["federation"],
        "endpoint_patterns": ["/_matrix/federation/(v1|v2)/send/"],
        "shared_extra_conf": {},
        "worker_extra_conf": "",
    },
    "event_persister": {
        "app": "synapse.app.generic_worker",
        "listener_resources": ["replication"],
        "endpoint_patterns": [],
        "shared_extra_conf": {},
        "worker_extra_conf": "",
    },
    "background_worker": {
        "app": "synapse.app.generic_worker",
        "listener_resources": [],
        "endpoint_patterns": [],
        # This worker cannot be sharded. Therefore there should only ever be one background
        # worker, and it should be named background_worker1
        "shared_extra_conf": {"run_background_tasks_on": "background_worker1"},
        "worker_extra_conf": "",
    },
    "event_creator": {
        "app": "synapse.app.generic_worker",
        "listener_resources": ["client"],
        "endpoint_patterns": [
            "^/_matrix/client/(api/v1|r0|v3|unstable)/rooms/.*/redact",
            "^/_matrix/client/(api/v1|r0|v3|unstable)/rooms/.*/send",
            "^/_matrix/client/(api/v1|r0|v3|unstable)/rooms/.*/(join|invite|leave|ban|unban|kick)$",
            "^/_matrix/client/(api/v1|r0|v3|unstable)/join/",
            "^/_matrix/client/(api/v1|r0|v3|unstable)/profile/",
            "^/_matrix/client/(v1|unstable/org.matrix.msc2716)/rooms/.*/batch_send",
        ],
        "shared_extra_conf": {},
        "worker_extra_conf": "",
    },
    "frontend_proxy": {
        "app": "synapse.app.frontend_proxy",
        "listener_resources": ["client", "replication"],
        "endpoint_patterns": ["^/_matrix/client/(api/v1|r0|v3|unstable)/keys/upload"],
        "shared_extra_conf": {},
        "worker_extra_conf": (
            "worker_main_http_uri: http://127.0.0.1:%d"
            % (MAIN_PROCESS_HTTP_LISTENER_PORT,)
        ),
    },
}

# Templates for sections that may be inserted multiple times in config files
NGINX_LOCATION_CONFIG_BLOCK = """
    location ~* {endpoint} {{
        proxy_pass {upstream};
        proxy_set_header X-Forwarded-For $remote_addr;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header Host $host;
    }}
"""

NGINX_UPSTREAM_CONFIG_BLOCK = """
upstream {upstream_worker_type} {{
{body}
}}
"""


# Utility functions
def log(txt: str) -> None:
    """Log something to the stdout.

    Args:
        txt: The text to log.
    """
    print(txt)


def error(txt: str) -> NoReturn:
    """Log something and exit with an error code.

    Args:
        txt: The text to log in error.
    """
    log(txt)
    sys.exit(2)


def convert(src: str, dst: str, **template_vars: object) -> None:
    """Generate a file from a template

    Args:
        src: Path to the input file.
        dst: Path to write to.
        template_vars: The arguments to replace placeholder variables in the template with.
    """
    # Read the template file
    # We disable autoescape to prevent template variables from being escaped,
    # as we're not using HTML.
    env = Environment(loader=FileSystemLoader(os.path.dirname(src)), autoescape=False)
    template = env.get_template(os.path.basename(src))

    # Generate a string from the template.
    rendered = template.render(**template_vars)

    # Write the generated contents to a file
    #
    # We use append mode in case the files have already been written to by something else
    # (for instance, as part of the instructions in a dockerfile).
    with open(dst, "a") as outfile:
        # In case the existing file doesn't end with a newline
        outfile.write("\n")

        outfile.write(rendered)


def add_sharding_to_shared_config(
    shared_config: dict,
    worker_type: str,
    worker_name: str,
    worker_port: int,
) -> None:
    """Given a dictionary representing a config file shared across all workers,
    append sharded worker information to it for the current worker_type instance.

    Args:
        shared_config: The config dict that all worker instances share (after being converted to YAML)
        worker_type: The type of worker (one of those defined in WORKERS_CONFIG).
        worker_name: The name of the worker instance.
        worker_port: The HTTP replication port that the worker instance is listening on.
    """
    # The instance_map config field marks the workers that write to various replication streams
    instance_map = shared_config.setdefault("instance_map", {})

    # Worker-type specific sharding config
    if worker_type == "pusher":
        shared_config.setdefault("pusher_instances", []).append(worker_name)

    elif worker_type == "federation_sender":
        shared_config.setdefault("federation_sender_instances", []).append(worker_name)

    elif worker_type == "event_persister":
        # Event persisters write to the events stream, so we need to update
        # the list of event stream writers
        shared_config.setdefault("stream_writers", {}).setdefault("events", []).append(
            worker_name
        )

        # Map of stream writer instance names to host/ports combos
        instance_map[worker_name] = {
            "host": "localhost",
            "port": worker_port,
        }

    elif worker_type == "media_repository":
        # The first configured media worker will run the media background jobs
        shared_config.setdefault("media_instance_running_background_jobs", worker_name)


def generate_base_homeserver_config() -> None:
    """Starts Synapse and generates a basic homeserver config, which will later be
    modified for worker support.

    Raises: CalledProcessError if calling start.py returned a non-zero exit code.
    """
    # start.py already does this for us, so just call that.
    # note that this script is copied in in the official, monolith dockerfile
    os.environ["SYNAPSE_HTTP_PORT"] = str(MAIN_PROCESS_HTTP_LISTENER_PORT)
    subprocess.check_output(["/usr/local/bin/python", "/start.py", "migrate_config"])


def generate_worker_files(
    environ: Mapping[str, str], config_path: str, data_dir: str
) -> None:
    """Read the desired list of workers from environment variables and generate
    shared homeserver, nginx and supervisord configs.

    Args:
        environ: os.environ instance.
        config_path: The location of the generated Synapse main worker config file.
        data_dir: The location of the synapse data directory. Where log and
            user-facing config files live.
    """
    # Note that yaml cares about indentation, so care should be taken to insert lines
    # into files at the correct indentation below.

    # shared_config is the contents of a Synapse config file that will be shared amongst
    # the main Synapse process as well as all workers.
    # It is intended mainly for disabling functionality when certain workers are spun up,
    # and adding a replication listener.

    # First read the original config file and extract the listeners block. Then we'll add
    # another listener for replication. Later we'll write out the result to the shared
    # config file.
    listeners = [
        {
            "port": 9093,
            "bind_address": "127.0.0.1",
            "type": "http",
            "resources": [{"names": ["replication"]}],
        }
    ]
    with open(config_path) as file_stream:
        original_config = yaml.safe_load(file_stream)
        original_listeners = original_config.get("listeners")
        if original_listeners:
            listeners += original_listeners

    # The shared homeserver config. The contents of which will be inserted into the
    # base shared worker jinja2 template.
    #
    # This config file will be passed to all workers, included Synapse's main process.
    shared_config: Dict[str, Any] = {"listeners": listeners}

    # List of dicts that describe workers.
    # We pass this to the Supervisor template later to generate the appropriate
    # program blocks.
    worker_descriptors: List[Dict[str, Any]] = []

    # Upstreams for load-balancing purposes. This dict takes the form of a worker type to the
    # ports of each worker. For example:
    # {
    #   worker_type: {1234, 1235, ...}}
    # }
    # and will be used to construct 'upstream' nginx directives.
    nginx_upstreams: Dict[str, Set[int]] = {}

    # A map of: {"endpoint": "upstream"}, where "upstream" is a str representing what will be
    # placed after the proxy_pass directive. The main benefit to representing this data as a
    # dict over a str is that we can easily deduplicate endpoints across multiple instances
    # of the same worker.
    #
    # An nginx site config that will be amended to depending on the workers that are
    # spun up. To be placed in /etc/nginx/conf.d.
    nginx_locations = {}

    # Read the desired worker configuration from the environment
    worker_types_env = environ.get("SYNAPSE_WORKER_TYPES", "").strip()
    if not worker_types_env:
        # No workers, just the main process
        worker_types = []
    else:
        # Split type names by comma
        worker_types = worker_types_env.split(",")

    # Create the worker configuration directory if it doesn't already exist
    os.makedirs("/conf/workers", exist_ok=True)

    # Start worker ports from this arbitrary port
    worker_port = 18009

    # A counter of worker_type -> int. Used for determining the name for a given
    # worker type when generating its config file, as each worker's name is just
    # worker_type + instance #
    worker_type_counter: Dict[str, int] = {}

    # A list of internal endpoints to healthcheck, starting with the main process
    # which exists even if no workers do.
    healthcheck_urls = ["http://localhost:8080/health"]

    # For each worker type specified by the user, create config values
    for worker_type in worker_types:
        worker_type = worker_type.strip()

        worker_config = WORKERS_CONFIG.get(worker_type)
        if worker_config:
            worker_config = worker_config.copy()
        else:
            log(worker_type + " is an unknown worker type! It will be ignored")
            continue

        new_worker_count = worker_type_counter.setdefault(worker_type, 0) + 1
        worker_type_counter[worker_type] = new_worker_count

        # Name workers by their type concatenated with an incrementing number
        # e.g. federation_reader1
        worker_name = worker_type + str(new_worker_count)
        worker_config.update(
            {"name": worker_name, "port": str(worker_port), "config_path": config_path}
        )

        # Update the shared config with any worker-type specific options
        shared_config.update(worker_config["shared_extra_conf"])

        healthcheck_urls.append("http://localhost:%d/health" % (worker_port,))

        # Check if more than one instance of this worker type has been specified
        worker_type_total_count = worker_types.count(worker_type)
        if worker_type_total_count > 1:
            # Update the shared config with sharding-related options if necessary
            add_sharding_to_shared_config(
                shared_config, worker_type, worker_name, worker_port
            )

        # Enable the worker in supervisord
        worker_descriptors.append(worker_config)

        # Add nginx location blocks for this worker's endpoints (if any are defined)
        for pattern in worker_config["endpoint_patterns"]:
            # Determine whether we need to load-balance this worker
            if worker_type_total_count > 1:
                # Create or add to a load-balanced upstream for this worker
                nginx_upstreams.setdefault(worker_type, set()).add(worker_port)

                # Upstreams are named after the worker_type
                upstream = "http://" + worker_type
            else:
                upstream = "http://localhost:%d" % (worker_port,)

            # Note that this endpoint should proxy to this upstream
            nginx_locations[pattern] = upstream

        # Write out the worker's logging config file

        log_config_filepath = generate_worker_log_config(environ, worker_name, data_dir)

        # Then a worker config file
        convert(
            "/conf/worker.yaml.j2",
            "/conf/workers/{name}.yaml".format(name=worker_name),
            **worker_config,
            worker_log_config_filepath=log_config_filepath,
        )

        worker_port += 1

    # Build the nginx location config blocks
    nginx_location_config = ""
    for endpoint, upstream in nginx_locations.items():
        nginx_location_config += NGINX_LOCATION_CONFIG_BLOCK.format(
            endpoint=endpoint,
            upstream=upstream,
        )

    # Determine the load-balancing upstreams to configure
    nginx_upstream_config = ""

    for upstream_worker_type, upstream_worker_ports in nginx_upstreams.items():
        body = ""
        for port in upstream_worker_ports:
            body += "    server localhost:%d;\n" % (port,)

        # Add to the list of configured upstreams
        nginx_upstream_config += NGINX_UPSTREAM_CONFIG_BLOCK.format(
            upstream_worker_type=upstream_worker_type,
            body=body,
        )

    # Finally, we'll write out the config files.

    # log config for the master process
    master_log_config = generate_worker_log_config(environ, "master", data_dir)
    shared_config["log_config"] = master_log_config

    # Find application service registrations
    appservice_registrations = None
    appservice_registration_dir = os.environ.get("SYNAPSE_AS_REGISTRATION_DIR")
    if appservice_registration_dir:
        # Scan for all YAML files that should be application service registrations.
        appservice_registrations = [
            str(reg_path.resolve())
            for reg_path in Path(appservice_registration_dir).iterdir()
            if reg_path.suffix.lower() in (".yaml", ".yml")
        ]

    workers_in_use = len(worker_types) > 0

    # Shared homeserver config
    convert(
        "/conf/shared.yaml.j2",
        "/conf/workers/shared.yaml",
        shared_worker_config=yaml.dump(shared_config),
        appservice_registrations=appservice_registrations,
        enable_redis=workers_in_use,
        workers_in_use=workers_in_use,
    )

    # Nginx config
    convert(
        "/conf/nginx.conf.j2",
        "/etc/nginx/conf.d/matrix-synapse.conf",
        worker_locations=nginx_location_config,
        upstream_directives=nginx_upstream_config,
        tls_cert_path=os.environ.get("SYNAPSE_TLS_CERT"),
        tls_key_path=os.environ.get("SYNAPSE_TLS_KEY"),
    )

    # Supervisord config
    os.makedirs("/etc/supervisor", exist_ok=True)
    convert(
        "/conf/supervisord.conf.j2",
        "/etc/supervisor/supervisord.conf",
        main_config_path=config_path,
        enable_redis=workers_in_use,
    )

    convert(
        "/conf/synapse.supervisord.conf.j2",
        "/etc/supervisor/conf.d/synapse.conf",
        workers=worker_descriptors,
        main_config_path=config_path,
    )

    # healthcheck config
    convert(
        "/conf/healthcheck.sh.j2",
        "/healthcheck.sh",
        healthcheck_urls=healthcheck_urls,
    )

    # Ensure the logging directory exists
    log_dir = data_dir + "/logs"
    if not os.path.exists(log_dir):
        os.mkdir(log_dir)


def generate_worker_log_config(
    environ: Mapping[str, str], worker_name: str, data_dir: str
) -> str:
    """Generate a log.config file for the given worker.

    Returns: the path to the generated file
    """
    # Check whether we should write worker logs to disk, in addition to the console
    extra_log_template_args = {}
    if environ.get("SYNAPSE_WORKERS_WRITE_LOGS_TO_DISK"):
        extra_log_template_args["LOG_FILE_PATH"] = "{dir}/logs/{name}.log".format(
            dir=data_dir, name=worker_name
        )
    # Render and write the file
    log_config_filepath = "/conf/workers/{name}.log.config".format(name=worker_name)
    convert(
        "/conf/log.config",
        log_config_filepath,
        worker_name=worker_name,
        **extra_log_template_args,
    )
    return log_config_filepath


def main(args: List[str], environ: MutableMapping[str, str]) -> None:
    config_dir = environ.get("SYNAPSE_CONFIG_DIR", "/data")
    config_path = environ.get("SYNAPSE_CONFIG_PATH", config_dir + "/homeserver.yaml")
    data_dir = environ.get("SYNAPSE_DATA_DIR", "/data")

    # override SYNAPSE_NO_TLS, we don't support TLS in worker mode,
    # this needs to be handled by a frontend proxy
    environ["SYNAPSE_NO_TLS"] = "yes"

    # Generate the base homeserver config if one does not yet exist
    if not os.path.exists(config_path):
        log("Generating base homeserver config")
        generate_base_homeserver_config()

    # This script may be run multiple times (mostly by Complement, see note at top of file).
    # Don't re-configure workers in this instance.
    mark_filepath = "/conf/workers_have_been_configured"
    if not os.path.exists(mark_filepath):
        # Always regenerate all other config files
        generate_worker_files(environ, config_path, data_dir)

        # Mark workers as being configured
        with open(mark_filepath, "w") as f:
            f.write("")

    # Start supervisord, which will start Synapse, all of the configured worker
    # processes, redis, nginx etc. according to the config we created above.
    log("Starting supervisord")
    os.execl(
        "/usr/local/bin/supervisord",
        "supervisord",
        "-c",
        "/etc/supervisor/supervisord.conf",
    )


if __name__ == "__main__":
    main(sys.argv, os.environ)
