"""

    AUTHOR:

        Khushal P Soonderji

    DATE:

        Tuesday, 8th Oct., 2024

    OBJECTIVE:

        This is the central location for the Quart module.
        We define the app here, and import and attach all blueprints here.

    REFERENCES:

        N/A

    DOWNLOADS:

        N/A

"""


#   *****************************************************************************************************************
#  *****                                                                                                          ****
# ***                                                   IMPORT                                                      ***
#  *****                                                                                                          ****
#   *****************************************************************************************************************


# To make sibling directories accessible for imports:
import sys
sys.path.append(".")
sys.path.append("..")

# For system level activities:
import gc
import os
import psutil

# For using Quart:
from quart import Quart, request, current_app
from quart_cors import cors

# Common:
from shared import constants

# My utils:
from utils_v2.string import json
from utils_v2.api import async_quart
from utils_v2.date_time import date_time
from utils_v2.database.async_mongo_v2 import AsyncMongo
from utils_v2.cache.async_redis_cache_v2 import AsyncRedisCache
from utils_v2.serialization.json_serializer import JSONSerializer
from utils_v2.api.async_quart import (
    set_api_version,
    read_input,
    log_request_to_mongo,
    should_not_be_under_maintenance,
    only_whitelisted_ips,
    limit_rate,
    validate_input,
    handle_cancelled_request
)

# GMail-related utils:
from utils_v2.goog.gmail.gmail_client import AsyncGMailClient, SCOPES_GMAIL_MAIL_MANAGEMENT

# To make REST API calls:
import httpx

# For debugging:
from icecream import IceCreamDebugger

# All the blueprints:
from api.blueprints.mail.oauth import mail_oauth_bp
from api.blueprints.mail.callback import mail_callback_bp
from api.blueprints.test.callback import test_callback_bp

# All the helpers:
from api.helpers.user import session


#   *****************************************************************************************************************
#  *****                                                                                                          ****
# ***                                           MACROS / ONE-TIME INIT                                              ***
#  *****                                                                                                          ****
#   *****************************************************************************************************************


# Quart related:
MODULE_BASE = constants.MODULE_NAME
APP_VERSION = constants.APP_VERSION


#   *****************************************************************************************************************
#  *****                                                                                                          ****
# ***                                                VARIABLES                                                      ***
#  *****                                                                                                          ****
#   *****************************************************************************************************************


# The Quart app:
app = Quart(__name__)
app = cors(app)
app.register_blueprint(mail_oauth_bp, url_prefix = f"/{MODULE_BASE}/mail")
app.register_blueprint(mail_callback_bp, url_prefix = f"/{MODULE_BASE}/mail")
app.register_blueprint(test_callback_bp, url_prefix = f"/{MODULE_BASE}/test")


#   *****************************************************************************************************************
#  *****                                                                                                          ****
# ***                                                  FUNCTIONS                                                    ***
#  *****                                                                                                          ****
#   *****************************************************************************************************************


def set_cpu_affinity(requested_cpus: list):

    """
    Sets the affinity of the current process to certain CPUs so that performance is boosted. The main factors that
    contribute to gains are cache-locality, reduced context switching, and effective resource management.
    :param requested_cpus: The array of integers of which CPU cores are preferred.
    :return: None.
    """

    # Get the number of available CPUs:
    num_cpus = psutil.cpu_count()

    # Wrap around logic for when a core has been request that doesn't exist on this machine.
    # This is useful in cases like developing on a local machine with just 4 cores, but your server has dozens of cores.
    valid_cpus = [cpu % num_cpus for cpu in requested_cpus]

    # Set the CPU affinity:
    psutil.Process().cpu_affinity(valid_cpus)


# ---------------------------------------------------------------------------------------------------------------------


@app.before_serving
@set_api_version(api_version = APP_VERSION)
@log_request_to_mongo(
    attr_name = "logs_mongo",
    project = constants.PROJECT_NAME,
    log_type = constants.MODULE_NAME,
    operation = "apiStart",
    log_input = True,
    log_output = True
)
async def app_startup(**kwargs):

    """
    To initialize the variables that you would like to use in this module.
    WARNING: ALL VARIABLES WILL BE INITIALIZED 'n' NUMBER OF TIMES, WHERE 'n' IS THE COUNT OF WORKERS DEPLOYED.
    SO, IF YOU WANT TO CONNECT TO A DATABASE AND YOU ALLOW A POOL-SIZE OF 10 AND IF YOU DEPLOY 4 WORKERS, YOU WILL END
    UP WITH 40 CONNECTIONS TO THE DATABASE.
    :return: None.
    """

    # Safe-halt mechanism for upgrades (for a single-worker run):
    current_app.is_under_maintenance = False

    # Debugging:
    enable_debugging = True if os.environ["DEBUG"].strip().lower() == "true" else False
    current_app.printer = IceCreamDebugger(prefix = f"{MODULE_BASE} (Q) | ", includeContext = True)
    if not enable_debugging: current_app.printer.disable()
    current_app.printer("initializing worker...")

    # Make an instance of an HTTP client to use to make API calls:
    current_app.http_client = httpx.AsyncClient(
        limits = httpx.Limits(
            max_connections = 100,  # ............ Maximum number of connections allowed in the pool.
            max_keepalive_connections = 50,  # ... Maximum number of connections that can be kept alive.
        ),
        timeout = httpx.Timeout(
            connect = 2.5,  # ... Shorter connection timeout.
            read = 2.5,  # ...... Like what EasyEcom gives.
            write = 10.0,  # .... Time to wait for sending data.
            pool = 120.0  # ..... Time to wait for a free connection from the pool.
        )
    )

    # Get the script credentials and data:
    script_id = os.environ["SCRIPT_ID"]
    response = await current_app.http_client.get(
        url = r"https://nexcom.ditscentre.in/internal/cred/get",
        headers = {"X-Script-Id": script_id}
    )
    script_cred = response.json().get("data")
    response = await current_app.http_client.get(
        url = r"https://nexcom.ditscentre.in/internal/data/get",
        headers = {"X-Script-Id": script_id}
    )
    current_app.script_data = response.json().get("data")

    # We set the CPU affinity:
    try: set_cpu_affinity(script_cred["cpuAffinity"])
    except Exception as exception: current_app.printer(exception)

    # Caching connections:
    current_app.rate_limit_cache = AsyncRedisCache(
        connection_string = script_cred["redisCache"]["rateLimit"]["connectionString"],
        debug = enable_debugging,
        debug_prefix = "RL Cache | "
    )
    current_app.module_cache = AsyncRedisCache(
        connection_string = script_cred["redisCache"]["funcReturn"]["connectionString"],
        serializer = JSONSerializer(),
        debug = enable_debugging,
        debug_prefix = "User Cache | "
    )

    # MongoDB connections:
    current_app.logs_mongo = AsyncMongo(
        connection_string = script_cred["mongoDb"]["logs"]["connectionString"],
        database_name = script_cred["mongoDb"]["logs"]["dbName"],
        max_connections = script_cred["mongoDb"]["logs"]["poolSize"],
        debug = enable_debugging
    )
    await current_app.logs_mongo.connect()
    current_app.data_mongo = AsyncMongo(
        connection_string = script_cred["mongoDb"]["data"]["connectionString"],
        database_name = script_cred["mongoDb"]["data"]["dbName"],
        max_connections = script_cred["mongoDb"]["data"]["poolSize"],
        debug = enable_debugging
    )
    await current_app.data_mongo.connect()

    # Create an instance to handle GMail-related activities:
    current_app.gmail_client = AsyncGMailClient(
        service_name = "gmail",
        oauth_json = script_cred["google"]["oauth"]["tcaoff"],
        http_client = current_app.http_client,
        redirect_url = r"https://api.thecaoffice.com/converse/mail/callback/gmail",
        scopes = SCOPES_GMAIL_MAIL_MANAGEMENT,
        debug = True,
        debug_prefix = "GMail (M) | ",
        debug_only_errors = False
    )

    # Pick the important stuff:
    current_app.whitelisted_ips = current_app.script_data["whitelistedIps"]

    # Register helpers:
    current_app.get_session = session.get_session

    # Remove unwanted/sensitive variables from RAM:
    del script_cred
    gc.collect()

    # Done here!
    current_app.printer("Worker ready!")


# ---------------------------------------------------------------------------------------------------------------------


@app.after_serving
@set_api_version(api_version = APP_VERSION)
@log_request_to_mongo(
    attr_name = "logs_mongo",
    project = constants.PROJECT_NAME,
    log_type = constants.MODULE_NAME,
    operation = "apiStop",
    log_input = True,
    log_output = True
)
async def app_shutdown(**kwargs):

    """
    This is called when "app.shutdown()" is called.
    :return: None.
    """

    message = "Shutting down..."
    current_app.printer(message)


# ---------------------------------------------------------------------------------------------------------------------


@app.route(f"/", methods = ["GET", "POST"])
@app.route(f"/{MODULE_BASE}", methods = ["GET", "POST"])
async def root():

    """
    To check if the service is running or not.
    Use this to monitor the service from your "watchman" script.
    :return: only "ok"
    """

    return "ok"


# ---------------------------------------------------------------------------------------------------------------------


@app.route(f"/metrics/memory", methods = ["GET", "POST"])
@app.route(f"/{MODULE_BASE}/metrics/memory", methods = ["GET", "POST"])
async def memory_metrics():

    """
    TO measure the metrics of the app.
    :return: A JSON of the metrics.
    """

    # Figure pout the parent process.
    # This is important for multi-worker environments:
    parent_pid = os.getppid()
    parent_process = psutil.Process(parent_pid)
    parent_mem_info = parent_process.memory_info()

    # Figure out all the children of the parent process:
    child_pids = [child.pid for child in parent_process.children()]
    child_processes = [psutil.Process(child_pid) for child_pid in child_pids]
    child_stats = []
    for pid, process in zip(child_pids, child_processes):
        mem_info = process.memory_info()
        child_stats.append({
            "pid": pid,
            "mem": round(mem_info.rss / (1024 ** 2), 2)
        })

    # Construct the response:
    metrics_json = {
        "parent": {
            "pid": parent_pid,
            "mem": round(parent_mem_info.rss / (1024 ** 2), 2)
        },
        "children": child_stats,
        "unit": {
            "mem": "MB"
        },
        "ts": date_time.get_current_ist_date_time(as_string = True)
    }

    # Done here:
    return metrics_json


# ---------------------------------------------------------------------------------------------------------------------


@app.route(f"/{MODULE_BASE}/debug/<action>", methods = ["POST", "GET"])
async def change_debug(action):

    """
    Enable or disable debugging for the entire microservice.
    WARNING: NOT RECOMMENDED FOR MULTI-WORKER DEPLOYMENTS.
    :param action: "enable" to allow debugging on the terminal, or "disable".
    :return: "enabled"/"disabled" if successful, else "ok"
    """

    # Enable or disable debugging only if the password matches:
    action = action.lower()
    if action == "enable": current_app.printer.enable()
    elif action == "disable": current_app.printer.disable()
    return "ok"


# ---------------------------------------------------------------------------------------------------------------------


@app.route(f"/{MODULE_BASE}/maintenance/<action>", methods = ["POST", "GET"])
async def change_maintenance(action):

    """
    Enable or disable debugging for the entire microservice.
    WARNING: NOT RECOMMENDED FOR MULTI-WORKER DEPLOYMENTS.
    :param action: "enable" to stop taking new requests on the API, or "disable".
    :return: "enabled"/"disabled" if successful, else "ok"
    """

    # Enable or disable debugging only if the password matches:
    action = action.lower()
    if action == "enable":
        current_app.is_under_maintenance = True
        os.environ["IS_UNDER_MAINTENANCE"] = "True"
    elif action == "disable":
        current_app.is_under_maintenance = False
        os.environ["IS_UNDER_MAINTENANCE"] = "False"
    return "ok"


#   *****************************************************************************************************************
#  *****                                                                                                          ****
# ***                                               MAIN PROGRAM                                                    ***
#  *****                                                                                                          ****
#   *****************************************************************************************************************


if __name__ == "__main__":

    # To get args from the terminal:
    import argparse

    # To run the ASGI:
    import uvicorn
    from multiprocessing import freeze_support

    # Get the config from the command-line:
    parser = argparse.ArgumentParser(description = f"Microservice for '{MODULE_BASE}' API.")
    parser.add_argument(
        "--workers",
        type = int,
        help = "The no. of threads to spin up for this instance!",
        default = 2
    )
    parser.add_argument(
        "--host",
        type = str,
        help = "The host for the app. e.g.: '0.0.0.0' or '127.0.0.1'.",
        default = "127.0.0.1"
    )
    parser.add_argument(
        "--port",
        type = int,
        help = "The port no. to bind the app to.",
        default = 8080
    )
    parser.add_argument(
        "--script-id",
        type = str,
        help = "The id of this script (will affect the loaded config)."
    )
    parser.add_argument(
        "--debug",
        action = "store_true",
        help = "Whether, or not, you want to see debugging messages in the terminal.",
        default = False
    )
    args = parser.parse_args()

    # Note down the config;
    os.environ["SCRIPT_ID"] = args.script_id
    os.environ["DEBUG"] = str(args.debug)

    # Run the gateway:
    freeze_support()
    uvicorn.run(
        app = "main:app",
        workers = args.workers,
        host = args.host,
        port = args.port
    )