import logging
from base64 import b64encode as b64enc
from calendar import timegm
from contextlib import asynccontextmanager
from datetime import datetime
from hashlib import sha256
from json import loads as json_loads
from os import getenv as env
from os.path import join, dirname
from uuid import uuid4

from dateutil.relativedelta import relativedelta
from dotenv import load_dotenv
from fastapi import FastAPI
from fastapi.requests import Request
from jose import jws, jwt, JWTError
from jose.constants import ALGORITHMS
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from starlette.middleware.cors import CORSMiddleware
from starlette.responses import StreamingResponse, JSONResponse as JSONr, HTMLResponse as HTMLr, Response, \
    RedirectResponse

from orm import init as db_init, migrate, Site, Instance, Origin, Lease

# Load variables
load_dotenv('../version.env')

# Get current timezone
TZ = datetime.now().astimezone().tzinfo

# Load basic variables
VERSION, COMMIT, DEBUG = env('VERSION', 'unknown'), env('COMMIT', 'unknown'), bool(env('DEBUG', False))

# Database connection
db = create_engine(str(env('DATABASE', 'sqlite:///db.sqlite')))
db_init(db), migrate(db)

# Load DLS variables (all prefixed with "INSTANCE_*" is used as "SERVICE_INSTANCE_*" or "SI_*" in official dls service)
DLS_URL = str(env('DLS_URL', 'localhost'))
DLS_PORT = int(env('DLS_PORT', '443'))
CORS_ORIGINS = str(env('CORS_ORIGINS', '')).split(',') if (env('CORS_ORIGINS')) else [f'https://{DLS_URL}']

ALLOTMENT_REF = str(env('ALLOTMENT_REF', '20000000-0000-0000-0000-000000000001'))  # todo


# FastAPI
@asynccontextmanager
async def lifespan(_: FastAPI):
    # on startup
    default_instance = Instance.get_default_instance(db)

    lease_renewal_period = default_instance.lease_renewal_period
    lease_renewal_delta = default_instance.get_lease_renewal_delta()
    client_token_expire_delta = default_instance.get_client_token_expire_delta()

    logger.info(f'''
    Using timezone: {str(TZ)}. Make sure this is correct and match your clients!
    
    Your clients will renew their license every {str(Lease.calculate_renewal(lease_renewal_period, lease_renewal_delta))}.
    If the renewal fails, the license is valid for {str(lease_renewal_delta)}.
    
    Your client-token file (.tok) is valid for {str(client_token_expire_delta)}.
    ''')

    logger.info(f'Debug is {"enabled" if DEBUG else "disabled"}.')

    validate_settings()

    yield

    # on shutdown
    logger.info(f'Shutting down ...')


config = dict(openapi_url=None, docs_url=None, redoc_url=None)  # dict(openapi_url='/-/openapi.json', docs_url='/-/docs', redoc_url='/-/redoc')
app = FastAPI(title='FastAPI-DLS', description='Minimal Delegated License Service (DLS).', version=VERSION, lifespan=lifespan, **config)

app.debug = DEBUG
app.add_middleware(
    CORSMiddleware,
    allow_origins=CORS_ORIGINS,
    allow_credentials=True,
    allow_methods=['*'],
    allow_headers=['*'],
)

# Logging
LOG_LEVEL = logging.DEBUG if DEBUG else logging.INFO
logging.basicConfig(format='[{levelname:^7}] [{module:^15}] {message}', style='{')
logger = logging.getLogger(__name__)
logger.setLevel(LOG_LEVEL)
logging.getLogger('util').setLevel(LOG_LEVEL)
logging.getLogger('NV').setLevel(LOG_LEVEL)


# Helper
def __get_token(request: Request, jwt_decode_key: "jose.jwt") -> dict:
    authorization_header = request.headers.get('authorization')
    token = authorization_header.split(' ')[1]
    return jwt.decode(token=token, key=jwt_decode_key, algorithms=ALGORITHMS.RS256, options={'verify_aud': False})


def validate_settings():
    session = sessionmaker(bind=db)()

    lease_expire_delta_min, lease_expire_delta_max = 86_400, 7_776_000
    for instance in session.query(Instance).all():
        lease_expire_delta = instance.lease_expire_delta
        if lease_expire_delta < 86_400 or lease_expire_delta > 7_776_000:
            logging.warning(f'> [ instance ]: {instance.instance_ref}: "lease_expire_delta" should be between {lease_expire_delta_min} and {lease_expire_delta_max}')

    session.close()


# Endpoints

@app.get('/', summary='Index')
async def index():
    return RedirectResponse('/-/readme')


@app.get('/-/', summary='* Index')
async def _index():
    return RedirectResponse('/-/readme')


@app.get('/-/health', summary='* Health')
async def _health():
    return JSONr({'status': 'up'})


@app.get('/-/config', summary='* Config', description='returns environment variables.')
async def _config():
    default_site, default_instance = Site.get_default_site(db), Instance.get_default_instance(db)

    return JSONr({
        'VERSION': str(VERSION),
        'COMMIT': str(COMMIT),
        'DEBUG': str(DEBUG),
        'DLS_URL': str(DLS_URL),
        'DLS_PORT': str(DLS_PORT),
        'SITE_KEY_XID': str(default_site.site_key),
        'INSTANCE_REF': str(default_instance.instance_ref),
        'ALLOTMENT_REF': [str(ALLOTMENT_REF)],
        'TOKEN_EXPIRE_DELTA': str(default_instance.get_token_expire_delta()),
        'LEASE_EXPIRE_DELTA': str(default_instance.get_lease_expire_delta()),
        'LEASE_RENEWAL_PERIOD': str(default_instance.lease_renewal_period),
        'CORS_ORIGINS': str(CORS_ORIGINS),
        'TZ': str(TZ),
    })


@app.get('/-/readme', summary='* Readme')
async def _readme():
    from markdown import markdown
    from util import load_file
    content = load_file(join(dirname(__file__), '../README.md')).decode('utf-8')
    return HTMLr(markdown(text=content, extensions=['tables', 'fenced_code', 'md_in_html', 'nl2br', 'toc']))


@app.get('/-/manage', summary='* Management UI')
async def _manage(request: Request):
    response = '''
    <!DOCTYPE html>
    <html>
        <head>
            <title>FastAPI-DLS Management</title>
        </head>
        <body>
            <button onclick="deleteOrigins()">delete ALL origins and their leases</button>
            <button onclick="deleteLease()">delete specific lease</button>
            
            <script>
                function deleteOrigins() {
                    const response = confirm('Are you sure you want to delete all origins and their leases?');

                    if (response) {
                        var xhr = new XMLHttpRequest();
                        xhr.open("DELETE", '/-/origins', true);
                        xhr.send();
                    }
                }
                function deleteLease(lease_ref) {
                    if(lease_ref === undefined)
                        lease_ref = window.prompt("Please enter 'lease_ref' which should be deleted");
                    if(lease_ref === null || lease_ref === "")
                        return
                    var xhr = new XMLHttpRequest();
                    xhr.open("DELETE", `/-/lease/${lease_ref}`, true);
                    xhr.send();
                }
            </script>
        </body>
    </html>
    '''
    return HTMLr(response)


@app.get('/-/origins', summary='* Origins')
async def _origins(request: Request, leases: bool = False):
    session = sessionmaker(bind=db)()
    response = []
    for origin in session.query(Origin).all():
        x = origin.serialize()
        if leases:
            x['leases'] = list(map(lambda _: _.serialize(), Lease.find_by_origin_ref(db, origin.origin_ref)))
        response.append(x)
    session.close()
    return JSONr(response)


@app.delete('/-/origins', summary='* Origins')
async def _origins_delete(request: Request):
    Origin.delete(db)
    return Response(status_code=201)


@app.get('/-/leases', summary='* Leases')
async def _leases(request: Request, origin: bool = False):
    session = sessionmaker(bind=db)()
    response = []
    for lease in session.query(Lease).all():
        x = lease.serialize()
        if origin:
            lease_origin = session.query(Origin).filter(Origin.origin_ref == lease.origin_ref).first()
            if lease_origin is not None:
                x['origin'] = lease_origin.serialize()
        response.append(x)
    session.close()
    return JSONr(response)


@app.delete('/-/leases/expired', summary='* Leases')
async def _lease_delete_expired(request: Request):
    Lease.delete_expired(db)
    return Response(status_code=201)


@app.delete('/-/lease/{lease_ref}', summary='* Lease')
async def _lease_delete(request: Request, lease_ref: str):
    if Lease.delete(db, lease_ref) == 1:
        return Response(status_code=201)
    return JSONr(status_code=404, content={'status': 404, 'detail': 'lease not found'})


# venv/lib/python3.9/site-packages/nls_core_service_instance/service_instance_token_manager.py
@app.get('/-/client-token', summary='* Client-Token', description='creates a new messenger token for this service instance')
async def _client_token():
    cur_time = datetime.utcnow()

    default_instance = Instance.get_default_instance(db)
    public_key = default_instance.get_public_key()
    # todo: implemented request parameter to support different instances
    jwt_encode_key = default_instance.get_jwt_encode_key()

    exp_time = cur_time + default_instance.get_client_token_expire_delta()

    payload = {
        "jti": str(uuid4()),
        "iss": "NLS Service Instance",
        "aud": "NLS Licensed Client",
        "iat": timegm(cur_time.timetuple()),
        "nbf": timegm(cur_time.timetuple()),
        "exp": timegm(exp_time.timetuple()),
        "update_mode": "ABSOLUTE",
        "scope_ref_list": [ALLOTMENT_REF],
        "fulfillment_class_ref_list": [],
        "service_instance_configuration": {
            "nls_service_instance_ref": default_instance.instance_ref,
            "svc_port_set_list": [
                {
                    "idx": 0,
                    "d_name": "DLS",
                    "svc_port_map": [{"service": "auth", "port": DLS_PORT}, {"service": "lease", "port": DLS_PORT}]
                }
            ],
            "node_url_list": [{"idx": 0, "url": DLS_URL, "url_qr": DLS_URL, "svc_port_set_idx": 0}]
        },
        "service_instance_public_key_configuration": {
            "service_instance_public_key_me": {
                "mod": hex(public_key.public_key().n)[2:],
                "exp": int(public_key.public_key().e),
            },
            "service_instance_public_key_pem": public_key.export_key().decode('utf-8'),
            "key_retention_mode": "LATEST_ONLY"
        },
    }

    content = jws.sign(payload, key=jwt_encode_key, headers=None, algorithm=ALGORITHMS.RS256)

    response = StreamingResponse(iter([content]), media_type="text/plain")
    filename = f'client_configuration_token_{datetime.now().strftime("%d-%m-%y-%H-%M-%S")}.tok'
    response.headers["Content-Disposition"] = f'attachment; filename={filename}'

    return response


# venv/lib/python3.9/site-packages/nls_services_auth/test/test_origins_controller.py
@app.post('/auth/v1/origin', description='find or create an origin')
async def auth_v1_origin(request: Request):
    j, cur_time = json_loads((await request.body()).decode('utf-8')), datetime.utcnow()

    origin_ref = j.get('candidate_origin_ref')
    logging.info(f'> [  origin  ]: {origin_ref}: {j}')

    data = Origin(
        origin_ref=origin_ref,
        hostname=j.get('environment').get('hostname'),
        guest_driver_version=j.get('environment').get('guest_driver_version'),
        os_platform=j.get('environment').get('os_platform'), os_version=j.get('environment').get('os_version'),
    )

    Origin.create_or_update(db, data)

    response = {
        "origin_ref": origin_ref,
        "environment": j.get('environment'),
        "svc_port_set_list": None,
        "node_url_list": None,
        "node_query_order": None,
        "prompts": None,
        "sync_timestamp": cur_time.isoformat()
    }

    return JSONr(response)


# venv/lib/python3.9/site-packages/nls_services_auth/test/test_origins_controller.py
@app.post('/auth/v1/origin/update', description='update an origin evidence')
async def auth_v1_origin_update(request: Request):
    j, cur_time = json_loads((await request.body()).decode('utf-8')), datetime.utcnow()

    origin_ref = j.get('origin_ref')
    logging.info(f'> [  update  ]: {origin_ref}: {j}')

    data = Origin(
        origin_ref=origin_ref,
        hostname=j.get('environment').get('hostname'),
        guest_driver_version=j.get('environment').get('guest_driver_version'),
        os_platform=j.get('environment').get('os_platform'), os_version=j.get('environment').get('os_version'),
    )

    Origin.create_or_update(db, data)

    response = {
        "environment": j.get('environment'),
        "prompts": None,
        "sync_timestamp": cur_time.isoformat()
    }

    return JSONr(response)


# venv/lib/python3.9/site-packages/nls_services_auth/test/test_auth_controller.py
# venv/lib/python3.9/site-packages/nls_core_auth/auth.py - CodeResponse
@app.post('/auth/v1/code', description='get an authorization code')
async def auth_v1_code(request: Request):
    j, cur_time = json_loads((await request.body()).decode('utf-8')), datetime.utcnow()

    origin_ref = j.get('origin_ref')
    logging.info(f'> [   code   ]: {origin_ref}: {j}')

    delta = relativedelta(minutes=15)
    expires = cur_time + delta

    default_site = Site.get_default_site(db)
    jwt_encode_key = Instance.get_default_instance(db).get_jwt_encode_key()

    payload = {
        'iat': timegm(cur_time.timetuple()),
        'exp': timegm(expires.timetuple()),
        'challenge': j.get('code_challenge'),
        'origin_ref': j.get('origin_ref'),
        'key_ref': default_site.site_key,
        'kid': default_site.site_key,
    }

    auth_code = jws.sign(payload, key=jwt_encode_key, headers={'kid': payload.get('kid')}, algorithm=ALGORITHMS.RS256)

    response = {
        "auth_code": auth_code,
        "sync_timestamp": cur_time.isoformat(),
        "prompts": None
    }

    return JSONr(response)


# venv/lib/python3.9/site-packages/nls_services_auth/test/test_auth_controller.py
# venv/lib/python3.9/site-packages/nls_core_auth/auth.py - TokenResponse
@app.post('/auth/v1/token', description='exchange auth code and verifier for token')
async def auth_v1_token(request: Request):
    j, cur_time = json_loads((await request.body()).decode('utf-8')), datetime.utcnow()

    default_site, default_instance = Site.get_default_site(db), Instance.get_default_instance(db)
    jwt_encode_key, jwt_decode_key = default_instance.get_jwt_encode_key(), default_instance.get_jwt_decode_key()

    try:
        payload = jwt.decode(token=j.get('auth_code'), key=jwt_decode_key, algorithms=[ALGORITHMS.RS256])
    except JWTError as e:
        return JSONr(status_code=400, content={'status': 400, 'title': 'invalid token', 'detail': str(e)})

    origin_ref = payload.get('origin_ref')
    logging.info(f'> [   auth   ]: {origin_ref}: {j}')

    # validate the code challenge
    challenge = b64enc(sha256(j.get('code_verifier').encode('utf-8')).digest()).rstrip(b'=').decode('utf-8')
    if payload.get('challenge') != challenge:
        return JSONr(status_code=401, content={'status': 401, 'detail': 'expected challenge did not match verifier'})

    access_expires_on = cur_time + default_instance.get_token_expire_delta()

    new_payload = {
        'iat': timegm(cur_time.timetuple()),
        'nbf': timegm(cur_time.timetuple()),
        'iss': 'https://cls.nvidia.org',
        'aud': 'https://cls.nvidia.org',
        'exp': timegm(access_expires_on.timetuple()),
        'origin_ref': origin_ref,
        'key_ref': default_site.site_key,
        'kid': default_site.site_key,
    }

    auth_token = jwt.encode(new_payload, key=jwt_encode_key, headers={'kid': payload.get('kid')}, algorithm=ALGORITHMS.RS256)

    response = {
        "expires": access_expires_on.isoformat(),
        "auth_token": auth_token,
        "sync_timestamp": cur_time.isoformat(),
    }

    return JSONr(response)


# venv/lib/python3.9/site-packages/nls_services_lease/test/test_lease_multi_controller.py
@app.post('/leasing/v1/lessor', description='request multiple leases (borrow) for current origin')
async def leasing_v1_lessor(request: Request):
    j, cur_time = json_loads((await request.body()).decode('utf-8')), datetime.utcnow()

    default_instance = Instance.get_default_instance(db)
    jwt_decode_key = default_instance.get_jwt_decode_key()

    try:
        token = __get_token(request, jwt_decode_key)
    except JWTError:
        return JSONr(status_code=401, content={'status': 401, 'detail': 'token is not valid'})

    origin_ref = token.get('origin_ref')
    scope_ref_list = j.get('scope_ref_list')
    logging.info(f'> [  create  ]: {origin_ref}: create leases for scope_ref_list {scope_ref_list}')

    lease_result_list = []
    for scope_ref in scope_ref_list:
        # if scope_ref not in [ALLOTMENT_REF]:
        #     return JSONr(status_code=500, detail=f'no service instances found for scopes: ["{scope_ref}"]')

        lease_ref = str(uuid4())
        expires = cur_time + default_instance.get_lease_expire_delta()
        lease_result_list.append({
            "ordinal": 0,
            # https://docs.nvidia.com/license-system/latest/nvidia-license-system-user-guide/index.html
            "lease": {
                "ref": lease_ref,
                "created": cur_time.isoformat(),
                "expires": expires.isoformat(),
                "recommended_lease_renewal": default_instance.lease_renewal_period,
                "offline_lease": "true",
                "license_type": "CONCURRENT_COUNTED_SINGLE"
            }
        })

        data = Lease(instance_ref=default_instance.instance_ref, origin_ref=origin_ref, lease_ref=lease_ref, lease_created=cur_time, lease_expires=expires)
        Lease.create_or_update(db, data)

    response = {
        "lease_result_list": lease_result_list,
        "result_code": "SUCCESS",
        "sync_timestamp": cur_time.isoformat(),
        "prompts": None
    }

    return JSONr(response)


# venv/lib/python3.9/site-packages/nls_services_lease/test/test_lease_multi_controller.py
# venv/lib/python3.9/site-packages/nls_dal_service_instance_dls/schema/service_instance/V1_0_21__product_mapping.sql
@app.get('/leasing/v1/lessor/leases', description='get active leases for current origin')
async def leasing_v1_lessor_lease(request: Request):
    cur_time = datetime.utcnow()

    jwt_decode_key = Instance.get_default_instance(db).get_jwt_decode_key()

    try:
        token = __get_token(request, jwt_decode_key)
    except JWTError:
        return JSONr(status_code=401, content={'status': 401, 'detail': 'token is not valid'})

    origin_ref = token.get('origin_ref')

    active_lease_list = list(map(lambda x: x.lease_ref, Lease.find_by_origin_ref(db, origin_ref)))
    logging.info(f'> [  leases  ]: {origin_ref}: found {len(active_lease_list)} active leases')

    response = {
        "active_lease_list": active_lease_list,
        "sync_timestamp": cur_time.isoformat(),
        "prompts": None
    }

    return JSONr(response)


# venv/lib/python3.9/site-packages/nls_services_lease/test/test_lease_single_controller.py
# venv/lib/python3.9/site-packages/nls_core_lease/lease_single.py
@app.put('/leasing/v1/lease/{lease_ref}', description='renew a lease')
async def leasing_v1_lease_renew(request: Request, lease_ref: str):
    cur_time = datetime.utcnow()

    default_instance = Instance.get_default_instance(db)
    jwt_decode_key = default_instance.get_jwt_decode_key()

    try:
        token = __get_token(request, jwt_decode_key)
    except JWTError:
        return JSONr(status_code=401, content={'status': 401, 'detail': 'token is not valid'})

    origin_ref = token.get('origin_ref')
    logging.info(f'> [  renew   ]: {origin_ref}: renew {lease_ref}')

    entity = Lease.find_by_origin_ref_and_lease_ref(db, origin_ref, lease_ref)
    if entity is None:
        return JSONr(status_code=404, content={'status': 404, 'detail': 'requested lease not available'})

    expires = cur_time + default_instance.get_lease_expire_delta()
    response = {
        "lease_ref": lease_ref,
        "expires": expires.isoformat(),
        "recommended_lease_renewal": default_instance.lease_renewal_period,
        "offline_lease": True,
        "prompts": None,
        "sync_timestamp": cur_time.isoformat(),
    }

    Lease.renew(db, entity, expires, cur_time)

    return JSONr(response)


# venv/lib/python3.9/site-packages/nls_services_lease/test/test_lease_single_controller.py
@app.delete('/leasing/v1/lease/{lease_ref}', description='release (return) a lease')
async def leasing_v1_lease_delete(request: Request, lease_ref: str):
    cur_time = datetime.utcnow()

    jwt_decode_key = Instance.get_default_instance(db).get_jwt_decode_key()

    try:
        token = __get_token(request, jwt_decode_key)
    except JWTError:
        return JSONr(status_code=401, content={'status': 401, 'detail': 'token is not valid'})

    origin_ref = token.get('origin_ref')
    logging.info(f'> [  return  ]: {origin_ref}: return {lease_ref}')

    entity = Lease.find_by_lease_ref(db, lease_ref)
    if entity.origin_ref != origin_ref:
        return JSONr(status_code=403, content={'status': 403, 'detail': 'access or operation forbidden'})
    if entity is None:
        return JSONr(status_code=404, content={'status': 404, 'detail': 'requested lease not available'})

    if Lease.delete(db, lease_ref) == 0:
        return JSONr(status_code=404, content={'status': 404, 'detail': 'lease not found'})

    response = {
        "lease_ref": lease_ref,
        "prompts": None,
        "sync_timestamp": cur_time.isoformat(),
    }

    return JSONr(response)


# venv/lib/python3.9/site-packages/nls_services_lease/test/test_lease_multi_controller.py
@app.delete('/leasing/v1/lessor/leases', description='release all leases')
async def leasing_v1_lessor_lease_remove(request: Request):
    cur_time = datetime.utcnow()

    jwt_decode_key = Instance.get_default_instance(db).get_jwt_decode_key()

    try:
        token = __get_token(request, jwt_decode_key)
    except JWTError:
        return JSONr(status_code=401, content={'status': 401, 'detail': 'token is not valid'})

    origin_ref = token.get('origin_ref')

    released_lease_list = list(map(lambda x: x.lease_ref, Lease.find_by_origin_ref(db, origin_ref)))
    deletions = Lease.cleanup(db, origin_ref)
    logging.info(f'> [  remove  ]: {origin_ref}: removed {deletions} leases')

    response = {
        "released_lease_list": released_lease_list,
        "release_failure_list": None,
        "sync_timestamp": cur_time.isoformat(),
        "prompts": None
    }

    return JSONr(response)


@app.post('/leasing/v1/lessor/shutdown', description='shutdown all leases')
async def leasing_v1_lessor_shutdown(request: Request):
    j, cur_time = json_loads((await request.body()).decode('utf-8')), datetime.utcnow()

    jwt_decode_key = Instance.get_default_instance(db).get_jwt_decode_key()

    token = j.get('token')
    token = jwt.decode(token=token, key=jwt_decode_key, algorithms=ALGORITHMS.RS256, options={'verify_aud': False})
    origin_ref = token.get('origin_ref')

    released_lease_list = list(map(lambda x: x.lease_ref, Lease.find_by_origin_ref(db, origin_ref)))
    deletions = Lease.cleanup(db, origin_ref)
    logging.info(f'> [ shutdown ]: {origin_ref}: removed {deletions} leases')

    response = {
        "released_lease_list": released_lease_list,
        "release_failure_list": None,
        "sync_timestamp": cur_time.isoformat(),
        "prompts": None
    }

    return JSONr(response)


if __name__ == '__main__':
    import uvicorn

    ###
    #
    # Running `python app/main.py` assumes that the user created a keypair, e.g. with openssl.
    #
    # openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout app/cert/webserver.key -out app/cert/webserver.crt
    #
    ###

    logging.info(f'> Starting dev-server ...')

    ssl_keyfile = join(dirname(__file__), 'cert/webserver.key')
    ssl_certfile = join(dirname(__file__), 'cert/webserver.crt')

    uvicorn.run('main:app', host='0.0.0.0', port=443, ssl_keyfile=ssl_keyfile, ssl_certfile=ssl_certfile, reload=True)