from __future__ import annotations
from contextlib import asynccontextmanager
import secrets
from typing import AsyncGenerator
from fastapi import Depends,FastAPI
from fastapi.exceptions import RequestValidationError
from fastapi.middleware.cors import CORSMiddleware
from fastapi.openapi.docs import get_redoc_html, get_swagger_ui_html
from fastapi.responses import HTMLResponse
from fastapi.security import HTTPBasic, HTTPBasicCredentials
from src.application.domain.enums import LogFormat,LogLevel
from src.application.domain.exceptions import ApplicationException,UnauthorizedException
from src.infrastructure.config.settings import get_settings
from src.infrastructure.vault import JwtKeyStore, start_jwt_keys_scheduler
from src.infrastructure.utils import generate_instance_id
from src.infrastructure.logger import logger
from src.infrastructure.metrics import PrometheusMetricsMiddleware, metrics_response
from src.infrastructure.config import settings
from src.presentation.handlers import application_exception_handler,unhandled_exception_handler,validation_exception_handler
from src.presentation.middleware import TraceIDMiddleware, SecurityHeadersMiddleware
from src.presentation.routing import kyc_router


security = HTTPBasic()


async def verify_credentials(credentials: HTTPBasicCredentials = Depends(security)) -> HTTPBasicCredentials:
    user_ok = secrets.compare_digest(credentials.username, settings.DOCS_USERNAME)
    pass_ok = secrets.compare_digest(credentials.password, settings.DOCS_PASSWORD)
    if not (user_ok and pass_ok):
        exception = UnauthorizedException()
        exception.headers = {'WWW-Authenticate': 'Basic'}
        raise exception
    return credentials


@asynccontextmanager
async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:

    instance_id = generate_instance_id()
    logger.set_format(LogFormat(settings.LOG_FORMAT.lower()))
    logger.set_min_level(LogLevel[settings.LOG_LEVEL.upper()])
    logger.set_instance_id(instance_id)
    logger.info(f'Users service instance started with id {instance_id}')

    jwt_store = JwtKeyStore(
        vault_addr=settings.VAULT_ADDR,
        vault_role_id=settings.VAULT_ROLE_ID,
        vault_secret_id=settings.VAULT_SECRET_ID,
        vault_namespace=settings.VAULT_NAMESPACE,
        mount_point=settings.VAULT_MOUNT_POINT,
        kid_path=settings.VAULT_JWT_KID_PATH,
        kids_prefix=settings.VAULT_JWT_KIDS_PREFIX,
    )

    await jwt_store.refresh()

    jwt_scheduler = start_jwt_keys_scheduler(jwt_store, refresh_seconds=settings.JWT_KEYS_REFRESH_SECONDS)

    app.state.jwt_key_store = jwt_store
    app.state.jwt_keys_scheduler = jwt_scheduler
    try:
        yield
    finally:
        app.state.jwt_keys_scheduler.shutdown(wait=False)
        logger.info(f'KYC service instance ended with id {instance_id}')


app: FastAPI = FastAPI(
    redoc_url=None,
    docs_url=None,
    lifespan=lifespan,
    title='Elcsa Users Service'
)

app.add_exception_handler(ApplicationException, application_exception_handler)
app.add_exception_handler(RequestValidationError, validation_exception_handler)
app.add_exception_handler(Exception, unhandled_exception_handler)

app.add_middleware(PrometheusMetricsMiddleware)

app.include_router(kyc_router)


app.add_middleware(TraceIDMiddleware, logger=logger)
app.add_middleware(
    SecurityHeadersMiddleware,
    hsts=True,
    hsts_preload=False,
    frame_options='DENY',
    referrer_policy='strict-origin-when-cross-origin',
    content_security_policy=(
        "default-src 'self'; "
        "script-src 'self' 'unsafe-inline' https://unpkg.com https://cdn.jsdelivr.net; "
        "style-src 'self' 'unsafe-inline' https://unpkg.com https://cdn.jsdelivr.net; "
        "img-src 'self' data: https:; "
        "font-src 'self' https://unpkg.com https://cdn.jsdelivr.net data:; "
        "connect-src 'self'; "
        "frame-ancestors 'none'; "
        "base-uri 'self'; "
        "object-src 'none'"
    ),
)
app.add_middleware(
    CORSMiddleware,
    allow_origins=[],
    allow_origin_regex=settings.CORS_ALLOW_ORIGIN_REGEX,
    allow_credentials=True,
    allow_methods=['*'],
    allow_headers=['*'],
)


@app.get('/docs', include_in_schema=False)
async def custom_swagger_ui_html(_credentials: HTTPBasicCredentials = Depends(verify_credentials)) -> HTMLResponse:
    '''Custom Swagger documentation, optionally protected with basic authentication.'''
    return get_swagger_ui_html(
        openapi_url=getattr(app, 'openapi_url', '/openapi.json'),
        title=getattr(app, 'title', 'FastAPI') + ' - Swagger UI',
        oauth2_redirect_url=getattr(app, 'swagger_ui_oauth2_redirect_url', None),
        swagger_js_url='https://unpkg.com/swagger-ui-dist@5/swagger-ui-bundle.js',
        swagger_css_url='https://unpkg.com/swagger-ui-dist@5/swagger-ui.css',
    )


@app.get('/redoc', include_in_schema=False)
async def custom_redoc_html(_credentials: HTTPBasicCredentials = Depends(verify_credentials)) -> HTMLResponse:
    '''Custom ReDoc documentation, optionally protected with basic authentication.'''
    return get_redoc_html(
        openapi_url=getattr(app, 'openapi_url', '/openapi.json'),
        title=getattr(app, 'title', 'FastAPI') + ' - ReDoc',
        redoc_js_url='https://cdn.jsdelivr.net/npm/redoc@next/bundles/redoc.standalone.js',
    )


@app.get('/metrics', include_in_schema=False)
async def metrics() -> Response:
    return await metrics_response()


@app.post('/ping')
async def ping() -> dict[str, str]:
    return {
        'message': 'pong',
        'status': 'ok',
    }

@app.get('/healthcheck')
@app.get('/health')
async def health() -> dict[str, str]:
    return {
        'status': 'ok',
    }