use std::future::{Ready, ready};

use actix_web::dev::Payload;
use actix_web::{FromRequest, HttpMessage, HttpRequest};
use uuid::Uuid;

pub const REQUEST_ID_HEADER: &str = "x-request-id";
pub const LEGACY_REQUEST_ID_HEADER: &str = "gitdata-request-id";
pub const REQUEST_ID_MAX_LEN: usize = 64;

#[derive(Debug, Clone)]
pub struct RequestId(pub String);

impl RequestId {
    pub fn from_header(value: Option<&str>) -> Self {
        Self(
            value
                .and_then(validate_request_id)
                .unwrap_or_else(new_request_id),
        )
    }

    pub fn as_str(&self) -> &str {
        &self.0
    }
}

pub fn validate_request_id(value: &str) -> Option<String> {
    let value = value.trim();
    if value.is_empty() || value.len() > REQUEST_ID_MAX_LEN {
        return None;
    }
    let allowed = value
        .bytes()
        .all(|byte| byte.is_ascii_alphanumeric() || matches!(byte, b'-' | b'_' | b'.' | b':'));
    allowed.then(|| value.to_owned())
}

pub fn new_request_id() -> String {
    Uuid::now_v7().to_string()
}

impl FromRequest for RequestId {
    type Error = actix_web::Error;
    type Future = Ready<Result<Self, Self::Error>>;

    fn from_request(req: &HttpRequest, _payload: &mut Payload) -> Self::Future {
        let request_id = req
            .extensions()
            .get::<RequestId>()
            .cloned()
            .unwrap_or_else(|| {
                RequestId::from_header(
                    req.headers()
                        .get(REQUEST_ID_HEADER)
                        .and_then(|value| value.to_str().ok()),
                )
            });
        ready(Ok(request_id))
    }
}