bark-apns 0.1.0

use std::{
    collections::{BTreeMap, BTreeSet},
    sync::Mutex,
    time::{Duration, SystemTime, UNIX_EPOCH},
};

use jsonwebtoken::{Algorithm, EncodingKey, Header, encode};
use reqwest::{
    StatusCode,
    header::{AUTHORIZATION, HeaderMap, HeaderValue},
};
use serde::{Deserialize, Serialize};

use crate::{
    error::{Error, Result},
    message::Message,
};

const TOKEN_REFRESH_AFTER: u64 = 45 * 60;
const DEFAULT_TEAM_ID: &str = "5U8LBRXG3A";
const DEFAULT_AUTH_KEY_ID: &str = "LH4T9V5U4R";
const DEFAULT_TOPIC: &str = "me.fin.bark";
const DEFAULT_PRIVATE_KEY: &str = "-----BEGIN PRIVATE KEY-----\n\
MIGTAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBHkwdwIBAQQg4vtC3g5L5HgKGJ2+\n\
T1eA0tOivREvEAY2g+juRXJkYL2gCgYIKoZIzj0DAQehRANCAASmOs3JkSyoGEWZ\n\
sUGxFs/4pw1rIlSV2IC19M8u3G5kq36upOwyFWj9Gi3Ejc9d3sC7+SHRqXrEAJow\n\
8/7tRpV+\n\
-----END PRIVATE KEY-----\n";

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
enum Environment {
    Production,
    Sandbox,
}

impl Environment {
    pub const fn host(self) -> &'static str {
        match self {
            Self::Production => "api.push.apple.com",
            Self::Sandbox => "api.sandbox.push.apple.com",
        }
    }
}

#[derive(Clone)]
struct Credentials {
    team_id: String,
    auth_key_id: String,
    topic: String,
    encoding_key: EncodingKey,
}

impl Credentials {
    fn new<T, K, O, P>(team_id: T, auth_key_id: K, topic: O, private_key_pem: P) -> Result<Self>
    where
        T: Into<String>,
        K: Into<String>,
        O: Into<String>,
        P: Into<String>,
    {
        let private_key_pem = private_key_pem.into();
        let encoding_key = EncodingKey::from_ec_pem(private_key_pem.as_bytes())?;

        Ok(Self {
            team_id: team_id.into(),
            auth_key_id: auth_key_id.into(),
            topic: topic.into(),
            encoding_key,
        })
    }

    fn team_id(&self) -> &str {
        &self.team_id
    }

    fn auth_key_id(&self) -> &str {
        &self.auth_key_id
    }

    fn topic(&self) -> &str {
        &self.topic
    }

    fn token(&self, issued_at: u64) -> Result<String> {
        let mut header = Header::new(Algorithm::ES256);
        header.kid = Some(self.auth_key_id.clone());

        let claims = ApnsClaims {
            iss: &self.team_id,
            iat: issued_at,
        };

        Ok(encode(&header, &claims, &self.encoding_key)?)
    }
}

/// Direct APNs client for Bark notifications.
///
/// `Bark` signs APNs provider tokens with Bark's default credentials by default
/// and sends serialized [`Message`] payloads to iOS device tokens. It talks to
/// APNs directly; no Bark server is contacted.
///
/// Device tokens are normalized before sending: surrounding angle brackets and
/// ASCII whitespace are removed, and duplicate tokens are sent once.
///
/// [`Message`]: crate::Message
pub struct Bark {
    credentials: Credentials,
    environment: Environment,
    async_http: reqwest::Client,
    blocking_http: reqwest::blocking::Client,
    token: Mutex<Option<CachedToken>>,
}

impl Bark {
    /// Creates a client using Bark's default APNs team id, key id, topic, and
    /// private key.
    ///
    /// This matches the public Bark app topic `me.fin.bark`.
    ///
    /// # Errors
    ///
    /// Returns an error if the built-in APNs key cannot be parsed or the HTTP
    /// clients cannot be constructed.
    pub fn new() -> Result<Self> {
        Self::with_credentials(
            DEFAULT_TEAM_ID,
            DEFAULT_AUTH_KEY_ID,
            DEFAULT_TOPIC,
            DEFAULT_PRIVATE_KEY,
        )
    }

    /// Creates a client with custom APNs credentials.
    ///
    /// Use this for a forked Bark app or a private APNs topic. The private key
    /// must be an APNs Auth Key in PEM format for ES256 signing.
    ///
    /// # Errors
    ///
    /// Returns an error if the private key cannot be parsed or the HTTP clients
    /// cannot be constructed.
    pub fn with_credentials<T, K, O, P>(
        team_id: T,
        auth_key_id: K,
        topic: O,
        private_key_pem: P,
    ) -> Result<Self>
    where
        T: Into<String>,
        K: Into<String>,
        O: Into<String>,
        P: Into<String>,
    {
        let credentials = Credentials::new(team_id, auth_key_id, topic, private_key_pem)?;
        Ok(Self {
            credentials,
            environment: Environment::Production,
            async_http: reqwest::ClientBuilder::new()
                .http2_adaptive_window(true)
                .build()
                .map_err(Error::HttpClient)?,
            blocking_http: reqwest::blocking::ClientBuilder::new()
                .http2_adaptive_window(true)
                .build()
                .map_err(Error::HttpClient)?,
            token: Mutex::new(None),
        })
    }

    /// Selects APNs production.
    ///
    /// This is the default and sends to `api.push.apple.com`.
    pub fn production(mut self) -> Self {
        self.environment = Environment::Production;
        self
    }

    /// Selects APNs sandbox.
    ///
    /// This sends to `api.sandbox.push.apple.com`, useful for development builds
    /// whose device tokens belong to the sandbox environment.
    pub fn sandbox(mut self) -> Self {
        self.environment = Environment::Sandbox;
        self
    }

    /// Returns the APNs team id used for provider-token signing.
    pub fn team_id(&self) -> &str {
        self.credentials.team_id()
    }

    /// Returns the APNs auth key id used in the JWT header.
    pub fn auth_key_id(&self) -> &str {
        self.credentials.auth_key_id()
    }

    /// Returns the APNs topic, normally Bark's bundle id.
    pub fn topic(&self) -> &str {
        self.credentials.topic()
    }

    /// Sends a message synchronously to one or more device tokens.
    ///
    /// The same serialized APNs payload is sent to each unique normalized token.
    /// For delete messages this method uses APNs `background` push type and
    /// priority `5`; otherwise it uses `alert` push type and priority `10`.
    ///
    /// # Errors
    ///
    /// Returns [`Error::ApnsFailures`] if any device fails. The error message
    /// includes the normalized device token and reason for each failed device.
    /// Validation, serialization, encryption, token-signing, and HTTP client
    /// errors are returned directly.
    ///
    /// [`Error::ApnsFailures`]: crate::Error::ApnsFailures
    pub fn send<I, D>(&self, message: &Message, devices: I) -> Result<()>
    where
        I: IntoIterator<Item = D>,
        D: Into<String>,
    {
        let body = message.payload_bytes()?;
        let headers = self.headers(message)?;
        let devices = collect_devices(devices);
        let mut failures = BTreeMap::new();

        for device in devices {
            let response = self
                .blocking_http
                .post(self.device_url(&device))
                .headers(headers.clone())
                .body(body.clone())
                .send();

            match response {
                Ok(response) => {
                    if !response.status().is_success() {
                        let status = response.status();
                        let reason = blocking_apns_reason(response);
                        failures.insert(device, format!("{status}: {reason}"));
                    }
                }
                Err(error) => {
                    failures.insert(device, error.to_string());
                }
            }
        }

        if failures.is_empty() {
            Ok(())
        } else {
            Err(Error::ApnsFailures(format_apns_failures(&failures)))
        }
    }

    /// Sends a message asynchronously to one or more device tokens.
    ///
    /// This has the same payload and error semantics as [`Bark::send`], but uses
    /// the asynchronous `reqwest` client.
    ///
    /// # Errors
    ///
    /// Returns [`Error::ApnsFailures`] if any device fails. The error message
    /// includes the normalized device token and reason for each failed device.
    /// Validation, serialization, encryption, token-signing, and HTTP client
    /// errors are returned directly.
    ///
    /// [`Error::ApnsFailures`]: crate::Error::ApnsFailures
    pub async fn send_async<I, D>(&self, message: &Message, devices: I) -> Result<()>
    where
        I: IntoIterator<Item = D>,
        D: Into<String>,
    {
        let body = message.payload_bytes()?;
        let headers = self.headers(message)?;
        let devices = collect_devices(devices);
        let mut failures = BTreeMap::new();

        for device in devices {
            let response = self
                .async_http
                .post(self.device_url(&device))
                .headers(headers.clone())
                .body(body.clone())
                .send()
                .await;

            match response {
                Ok(response) => {
                    if !response.status().is_success() {
                        let status = response.status();
                        let reason = async_apns_reason(response).await;
                        failures.insert(device, format!("{status}: {reason}"));
                    }
                }
                Err(error) => {
                    failures.insert(device, error.to_string());
                }
            }
        }

        if failures.is_empty() {
            Ok(())
        } else {
            Err(Error::ApnsFailures(format_apns_failures(&failures)))
        }
    }

    fn headers(&self, message: &Message) -> Result<HeaderMap> {
        message.validate_headers()?;

        let mut headers = HeaderMap::new();
        let authorization = format!("bearer {}", self.apns_token()?);
        headers.insert(
            AUTHORIZATION,
            HeaderValue::from_str(&authorization).map_err(|source| Error::InvalidHeaderValue {
                name: "authorization",
                source,
            })?,
        );
        headers.insert(
            "apns-topic",
            HeaderValue::from_str(self.credentials.topic()).map_err(|source| {
                Error::InvalidHeaderValue {
                    name: "apns-topic",
                    source,
                }
            })?,
        );
        headers.insert(
            "apns-push-type",
            HeaderValue::from_static(if message.is_delete() {
                "background"
            } else {
                "alert"
            }),
        );
        headers.insert(
            "apns-priority",
            HeaderValue::from_static(if message.is_delete() { "5" } else { "10" }),
        );

        if let Some(id) = message.id_value() {
            headers.insert(
                "apns-collapse-id",
                HeaderValue::from_str(id).map_err(|source| Error::InvalidHeaderValue {
                    name: "apns-collapse-id",
                    source,
                })?,
            );
        }

        Ok(headers)
    }

    fn apns_token(&self) -> Result<String> {
        let now = unix_timestamp();
        let mut cached = self.token.lock().expect("APNs token cache poisoned");

        if let Some(cached) = cached.as_ref()
            && cached.issued_at + TOKEN_REFRESH_AFTER > now
        {
            return Ok(cached.value.clone());
        }

        let value = self.credentials.token(now)?;
        *cached = Some(CachedToken {
            issued_at: now,
            value: value.clone(),
        });
        Ok(value)
    }

    fn device_url(&self, device: &str) -> String {
        format!("https://{}/3/device/{device}", self.environment.host())
    }
}

#[derive(Clone, Debug)]
struct CachedToken {
    issued_at: u64,
    value: String,
}

#[derive(Debug, Serialize)]
struct ApnsClaims<'a> {
    iss: &'a str,
    iat: u64,
}

#[derive(Debug, Deserialize)]
struct ApnsErrorBody {
    reason: Option<String>,
}

fn collect_devices<I, D>(devices: I) -> Vec<String>
where
    I: IntoIterator<Item = D>,
    D: Into<String>,
{
    devices
        .into_iter()
        .filter_map(|device| {
            let normalized = normalize_device_token(device.into());
            (!normalized.is_empty()).then_some(normalized)
        })
        .collect::<BTreeSet<_>>()
        .into_iter()
        .collect()
}

fn normalize_device_token(device: String) -> String {
    device
        .trim()
        .trim_start_matches('<')
        .trim_end_matches('>')
        .chars()
        .filter(|ch| !ch.is_ascii_whitespace())
        .collect()
}

async fn async_apns_reason(response: reqwest::Response) -> String {
    let status = response.status();
    match response.text().await {
        Ok(text) => apns_reason_from_text(status, &text),
        Err(error) => error.to_string(),
    }
}

fn blocking_apns_reason(response: reqwest::blocking::Response) -> String {
    let status = response.status();
    match response.text() {
        Ok(text) => apns_reason_from_text(status, &text),
        Err(error) => error.to_string(),
    }
}

fn apns_reason_from_text(status: StatusCode, text: &str) -> String {
    if text.trim().is_empty() {
        return status.to_string();
    }

    serde_json::from_str::<ApnsErrorBody>(text)
        .ok()
        .and_then(|body| body.reason)
        .unwrap_or_else(|| text.to_owned())
}

fn format_apns_failures(failures: &BTreeMap<String, String>) -> String {
    failures
        .iter()
        .map(|(device, reason)| format!("{device}: {reason}"))
        .collect::<Vec<_>>()
        .join("; ")
}

fn unix_timestamp() -> u64 {
    SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap_or_else(|_| Duration::from_secs(0))
        .as_secs()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn credentials_accept_str_and_string() {
        let credentials = Credentials::new(
            String::from(DEFAULT_TEAM_ID),
            DEFAULT_AUTH_KEY_ID,
            DEFAULT_TOPIC,
            DEFAULT_PRIVATE_KEY,
        )
        .unwrap();

        assert_eq!(credentials.team_id(), DEFAULT_TEAM_ID);
        assert_eq!(credentials.auth_key_id(), DEFAULT_AUTH_KEY_ID);
        assert_eq!(credentials.topic(), DEFAULT_TOPIC);
    }

    #[test]
    fn device_tokens_are_normalized_and_deduped() {
        let devices = collect_devices(["<aa bb>", "aabb", "  ", "cc"]);

        assert_eq!(devices, vec!["aabb", "cc"]);
    }
}