taba-client 0.1.0

//! The client: the configuration, the call with the common contract's retries (doc 19, section 18.4) and the
//! nine operations of the surface (section 18.3).

use std::fmt;
use std::sync::Arc;
use std::time::Duration;

use crate::base64;
use crate::http::{self, Request, Response, Url};
use crate::json::{self, Fields};
use crate::transport::{TcpTransport, Timeouts, Transport, TransportError};

/// The version of the API contract this connector implements (UC-CNT-028).
pub const CONTRACT_VERSION: &str = "1";

/// Above this, `consume` waits no more than the `waitTime` plus the slack below.
const LONG_POLL_SLACK: Duration = Duration::from_secs(10);

#[derive(Debug, Clone)]
pub struct Config {
    /// Address of the client API (`http://host:port` or `https://...`).
    pub base_url: String,
    pub token: Option<String>,
    pub connect_timeout: Duration,
    pub request_timeout: Duration,
    /// Attempts, counting the first.
    pub max_attempts: u32,
    pub user_agent: String,
    /// CA certificate (PEM) to trust, besides the system roots.
    pub ca_pem: Option<Vec<u8>>,
}

impl Config {
    pub fn new(base_url: impl Into<String>) -> Config {
        Config {
            base_url: base_url.into(),
            token: None,
            connect_timeout: Duration::from_secs(5),
            request_timeout: Duration::from_secs(30),
            max_attempts: 3,
            user_agent: format!("taba-rust/{}", env!("CARGO_PKG_VERSION")),
            ca_pem: None,
        }
    }
}

/// The only kind of error of the connector: the API `ErrorResponse`, or a failure of the client itself
/// (`status` zero and `code` `client.network`, `client.timeout` or `client.invalid-config`).
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Error {
    pub status: u16,
    pub code: String,
    pub message: String,
    pub request_id: Option<String>,
    /// Seconds of the `Retry-After`, if it came.
    pub retry_after: Option<u64>,
    /// The `details` list of the `ErrorResponse`, as JSON text.
    pub details: Option<String>,
    /// The response body, as it came (empty on a client failure).
    pub body: Vec<u8>,
}

impl Error {
    /// An error of the client itself (`status` zero), for whoever uses the connector to build their own.
    pub fn from_message(code: &str, message: impl Into<String>) -> Error {
        Error::client(code, message)
    }

    fn client(code: &str, message: impl Into<String>) -> Error {
        Error {
            status: 0,
            code: code.to_owned(),
            message: message.into(),
            request_id: None,
            retry_after: None,
            details: None,
            body: Vec::new(),
        }
    }

    /// A failure of the client itself, not a server response.
    pub fn is_client_side(&self) -> bool {
        self.status == 0
    }
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}: {}", self.code, self.message)?;
        if let Some(id) = &self.request_id {
            write!(f, " (requestId {id})")?;
        }
        Ok(())
    }
}

impl std::error::Error for Error {}

/// A call to the API, before it becomes HTTP.
#[derive(Debug, Clone)]
pub struct Call {
    pub method: &'static str,
    /// Path with the segments already encoded (`/topics/orders`).
    pub path: String,
    pub query: Vec<(String, String)>,
    pub body: Vec<u8>,
    /// Only applies with a body; default `application/json`.
    /// Extra headers (an `Accept` of its own replaces the default `application/json`).
    pub headers: Vec<(String, String)>,
    pub content_type: Option<String>,
    pub request_id: Option<String>,
    pub traceparent: Option<String>,
    /// Overrides the total time of the call (`consume` uses `waitTime + 10 s`).
    pub timeout: Option<Duration>,
    /// Retries `502` and `504`: only publishing to a FIFO queue, where the primary deduplicates.
    pub retry_gateway: bool,
    /// After a `503`, these responses count as success (the operation had already been applied):
    /// creating a topic (`409 topic.already-exists`) and deleting (`404`).
    pub recover: Vec<(u16, &'static str)>,
}

impl Call {
    pub fn new(method: &'static str, path: impl Into<String>) -> Call {
        Call {
            method,
            path: path.into(),
            query: Vec::new(),
            body: Vec::new(),
            headers: Vec::new(),
            content_type: None,
            request_id: None,
            traceparent: None,
            timeout: None,
            retry_gateway: false,
            recover: Vec::new(),
        }
    }

    pub fn query(mut self, key: &str, value: impl ToString) -> Call {
        self.query.push((key.to_owned(), value.to_string()));
        self
    }

    pub fn json_body(mut self, body: String) -> Call {
        self.body = body.into_bytes();
        self
    }
}

/// The response of a call that succeeded.
#[derive(Debug, Clone)]
pub struct Reply {
    pub status: u16,
    pub headers: Vec<(String, String)>,
    pub body: Vec<u8>,
    pub request_id: Option<String>,
    /// `true` when the response is a `409`/`404` accepted as success after a `503` (the operation
    /// had been applied on the previous attempt).
    pub recovered: bool,
}

impl Reply {
    pub fn text(&self) -> String {
        String::from_utf8_lossy(&self.body).into_owned()
    }
}

type Sleeper = Arc<dyn Fn(Duration) + Send + Sync>;

pub struct Client {
    config: Config,
    url: Url,
    transport: Box<dyn Transport>,
    sleeper: Sleeper,
}

impl Client {
    pub fn new(config: Config) -> Result<Client, Error> {
        let transport = TcpTransport::new(config.ca_pem.clone());
        Client::with_transport(config, Box::new(transport), Arc::new(std::thread::sleep))
    }

    /// To swap the network stack (and, in tests, the wait between attempts).
    pub fn with_transport(
        config: Config,
        transport: Box<dyn Transport>,
        sleeper: Sleeper,
    ) -> Result<Client, Error> {
        let url =
            Url::parse(&config.base_url).map_err(|m| Error::client("client.invalid-config", m))?;
        Ok(Client {
            config,
            url,
            transport,
            sleeper,
        })
    }

    pub fn config(&self) -> &Config {
        &self.config
    }

    fn wire_request(&self, call: &Call) -> Request {
        let mut headers = Vec::new();
        if let Some(token) = &self.config.token {
            headers.push(("Authorization".to_owned(), format!("Bearer {token}")));
        }
        if !call
            .headers
            .iter()
            .any(|(k, _)| k.eq_ignore_ascii_case("accept"))
        {
            headers.push(("Accept".to_owned(), "application/json".to_owned()));
        }
        headers.extend(call.headers.iter().cloned());
        headers.push(("User-Agent".to_owned(), self.config.user_agent.clone()));
        if !call.body.is_empty() {
            headers.push((
                "Content-Type".to_owned(),
                call.content_type
                    .clone()
                    .unwrap_or_else(|| "application/json".to_owned()),
            ));
        }
        if let Some(id) = &call.request_id {
            headers.push(("X-Request-Id".to_owned(), id.clone()));
        }
        if let Some(tp) = &call.traceparent {
            headers.push(("traceparent".to_owned(), tp.clone()));
        }
        Request {
            method: call.method.to_owned(),
            target: http::build_target(&self.url.base_path, &call.path, &call.query),
            headers,
            body: call.body.clone(),
        }
    }

    /// Makes the call, retrying only what the contract says to retry (section 18.4):
    /// `429` and `503` (waiting for the `Retry-After`, or 1 s, 2 s, 4 s), `502` and `504` only with
    /// `retry_gateway`, and a network failure **before** sending. Never a `4xx` (except `429`), nor
    /// a failure after sending the body, nor a timeout.
    pub fn call(&self, call: &Call) -> Result<Reply, Error> {
        let request = self.wire_request(call);
        let timeouts = Timeouts {
            connect: self.config.connect_timeout,
            total: call.timeout.unwrap_or(self.config.request_timeout),
        };
        let max = self.config.max_attempts.max(1);
        let mut attempt = 1;
        let mut after_503 = false;
        loop {
            let backoff = Duration::from_secs(1 << (attempt - 1).min(6));
            match self.transport.send(&self.url, &request, &timeouts) {
                Ok(response) => {
                    if response.status < 400 {
                        return Ok(reply(response, false));
                    }
                    if after_503
                        && call.recover.iter().any(|(status, code)| {
                            *status == response.status
                                && error_code(&response).as_deref() == Some(*code)
                        })
                    {
                        return Ok(reply(response, true));
                    }
                    let error = error_from(&response);
                    let retry = match response.status {
                        429 | 503 => true,
                        502 | 504 => call.retry_gateway,
                        _ => false,
                    };
                    if !retry || attempt >= max {
                        return Err(error);
                    }
                    after_503 |= response.status == 503;
                    (self.sleeper)(
                        error
                            .retry_after
                            .map(Duration::from_secs)
                            .unwrap_or(backoff),
                    );
                }
                Err(TransportError::Connect(message)) => {
                    if attempt >= max {
                        return Err(Error::client("client.network", message));
                    }
                    after_503 = true;
                    (self.sleeper)(backoff);
                }
                Err(TransportError::Timeout { sent: false }) => {
                    if attempt >= max {
                        return Err(Error::client(
                            "client.timeout",
                            "timed out opening the connection",
                        ));
                    }
                    after_503 = true;
                    (self.sleeper)(backoff);
                }
                Err(TransportError::Timeout { sent: true }) => {
                    return Err(Error::client(
                        "client.timeout",
                        "timed out waiting for the response",
                    ));
                }
                Err(TransportError::Io(message)) => {
                    return Err(Error::client("client.network", message))
                }
                Err(TransportError::Protocol(message)) => {
                    return Err(Error::client(
                        "client.network",
                        format!("invalid response: {message}"),
                    ))
                }
            }
            attempt += 1;
        }
    }
}

fn reply(response: Response, recovered: bool) -> Reply {
    Reply {
        request_id: response.header("x-request-id").map(str::to_owned),
        status: response.status,
        headers: response.headers,
        body: response.body,
        recovered,
    }
}

fn error_code(response: &Response) -> Option<String> {
    let text = std::str::from_utf8(&response.body).ok()?;
    Fields::parse(text).ok()?.string("code")
}

/// The response's `ErrorResponse`; if the body is not one, the error carries the code `http.<status>`.
fn error_from(response: &Response) -> Error {
    let text = String::from_utf8_lossy(&response.body);
    let fields = Fields::parse(&text).ok();
    let header_request_id = response.header("x-request-id").map(str::to_owned);
    let (code, message, request_id, details) = match &fields {
        Some(f) if f.string("code").is_some() => (
            f.string("code").unwrap_or_default(),
            f.string("message").unwrap_or_default(),
            f.string("requestId").or(header_request_id),
            f.raw("details").map(str::to_owned),
        ),
        _ => (
            format!("http.{}", response.status),
            if text.trim().is_empty() {
                format!("response {} with no body", response.status)
            } else {
                text.trim().chars().take(300).collect()
            },
            header_request_id,
            None,
        ),
    };
    Error {
        status: response.status,
        code,
        message,
        request_id,
        retry_after: response
            .header("retry-after")
            .and_then(|v| v.trim().parse().ok()),
        details,
        body: response.body.clone(),
    }
}

// ---------------------------------------------------------------------------------------------
// Modelos
// ---------------------------------------------------------------------------------------------

fn bad_response(what: &str, e: json::JsonError) -> Error {
    Error::client("client.invalid-response", format!("{what}: {e}"))
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Topic {
    pub id: String,
    pub name: String,
    /// `queue` or `distributor`.
    pub topic_type: String,
    pub created_at: String,
    pub fifo: Option<bool>,
    pub volatile: Option<bool>,
    /// The topic JSON, as the server returned it.
    pub raw: String,
}

impl Topic {
    pub fn parse(raw: &str) -> Result<Topic, Error> {
        let f = Fields::parse(raw).map_err(|e| bad_response("topic", e))?;
        Ok(Topic {
            id: f.string("id").unwrap_or_default(),
            name: f.string("name").unwrap_or_default(),
            topic_type: f.string("type").unwrap_or_default(),
            created_at: f.string("createdAt").unwrap_or_default(),
            fifo: f.boolean("fifo"),
            volatile: f.boolean("volatile"),
            raw: raw.to_owned(),
        })
    }
}

/// A page (`Page<T>`): the items and the cursor of the next one, if any.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Page<T> {
    pub items: Vec<T>,
    pub next_cursor: Option<String>,
    pub raw: String,
}

fn parse_page<T>(raw: &str, item: impl Fn(&str) -> Result<T, Error>) -> Result<Page<T>, Error> {
    let f = Fields::parse(raw).map_err(|e| bad_response("page", e))?;
    let items_raw = f.raw("items").unwrap_or("[]");
    let items = json::array_items(items_raw)
        .map_err(|e| bad_response("page items", e))?
        .into_iter()
        .map(item)
        .collect::<Result<Vec<_>, _>>()?;
    Ok(Page {
        items,
        next_cursor: f.string("nextCursor"),
        raw: raw.to_owned(),
    })
}

/// A delivered message. The `body` always comes out as bytes (section 18.4).
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Message {
    pub id: String,
    pub body: Vec<u8>,
    pub content_type: String,
    pub receipt_token: String,
    pub delivery_count: u64,
    pub published_at: String,
    pub invisible_until: String,
    pub group_id: Option<String>,
    pub deduplication_id: Option<String>,
    pub dead_lettered_at: Option<String>,
    pub dead_letter_reason: Option<String>,
    /// The message JSON, as the server returned it.
    pub raw: String,
}

fn is_json_type(content_type: &str) -> bool {
    let media = content_type
        .split(';')
        .next()
        .unwrap_or_default()
        .trim()
        .to_ascii_lowercase();
    media == "application/json" || media.ends_with("+json")
}

impl Message {
    pub fn parse(raw: &str) -> Result<Message, Error> {
        let f = Fields::parse(raw).map_err(|e| bad_response("message", e))?;
        let content_type = f
            .string("contentType")
            .unwrap_or_else(|| "application/json".to_owned());
        let body = match f.raw("body") {
            None => Vec::new(),
            Some(body) if f.string("bodyEncoding").as_deref() == Some("base64") => {
                let text =
                    json::decode_string(body).map_err(|e| bad_response("message body", e))?;
                base64::decode(&text).ok_or_else(|| {
                    Error::client("client.invalid-response", "invalid base64 body")
                })?
            }
            Some(body) if is_json_type(&content_type) => body.as_bytes().to_vec(),
            Some(body) => json::decode_string(body)
                .map_err(|e| bad_response("message body", e))?
                .into_bytes(),
        };
        Ok(Message {
            id: f.string("id").unwrap_or_default(),
            body,
            content_type,
            receipt_token: f.string("receiptToken").unwrap_or_default(),
            delivery_count: f.unsigned("deliveryCount").unwrap_or(0),
            published_at: f.string("publishedAt").unwrap_or_default(),
            invisible_until: f.string("invisibleUntil").unwrap_or_default(),
            group_id: f.string("groupId"),
            deduplication_id: f.string("deduplicationId"),
            dead_lettered_at: f.string("deadLetteredAt"),
            dead_letter_reason: f.string("deadLetterReason"),
            raw: raw.to_owned(),
        })
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct PublishResponse {
    /// The message `id` (queue). Absent from a distributor's response.
    pub id: Option<String>,
    /// FIFO queue only.
    pub duplicate: Option<bool>,
    /// Distributor only: how many queues matched.
    pub matched: Option<u64>,
    pub raw: String,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct VisibilityResponse {
    pub id: String,
    pub invisible_until: String,
    pub raw: String,
}

// ---------------------------------------------------------------------------------------------
// Requests
// ---------------------------------------------------------------------------------------------

fn json_map(pairs: &[(String, String)]) -> String {
    let items: Vec<String> = pairs
        .iter()
        .map(|(k, v)| format!("{}:{}", json::quote(k), json::quote(v)))
        .collect();
    format!("{{{}}}", items.join(","))
}

fn json_list(items: &[String]) -> String {
    let items: Vec<String> = items.iter().map(|i| json::quote(i)).collect();
    format!("[{}]", items.join(","))
}

/// `POST /topics`. The connector sends only what was filled in; whatever does not apply to the type, the server
/// refuses.
#[derive(Debug, Clone, Default)]
pub struct TopicRequest {
    pub name: String,
    /// `queue` or `distributor`.
    pub topic_type: String,
    pub tags: Vec<(String, String)>,
    pub prefixes: Vec<String>,
    pub volatile: Option<bool>,
    pub idle_timeout: Option<u64>,
    pub fifo: Option<bool>,
    pub max_message_bytes: Option<u64>,
    pub ttl: Option<u64>,
    pub max_deliveries: Option<u64>,
}

impl TopicRequest {
    pub fn to_json(&self) -> String {
        let mut fields = vec![
            format!("\"name\":{}", json::quote(&self.name)),
            format!("\"type\":{}", json::quote(&self.topic_type)),
        ];
        if !self.tags.is_empty() {
            fields.push(format!("\"tags\":{}", json_map(&self.tags)));
        }
        if !self.prefixes.is_empty() {
            fields.push(format!("\"prefixes\":{}", json_list(&self.prefixes)));
        }
        if let Some(v) = self.volatile {
            fields.push(format!("\"volatile\":{v}"));
        }
        if let Some(v) = self.idle_timeout {
            fields.push(format!("\"idleTimeout\":{v}"));
        }
        if let Some(v) = self.fifo {
            fields.push(format!("\"fifo\":{v}"));
        }
        if let Some(v) = self.max_message_bytes {
            fields.push(format!("\"maxMessageBytes\":{v}"));
        }
        if let Some(v) = self.ttl {
            fields.push(format!("\"ttl\":{v}"));
        }
        if let Some(v) = self.max_deliveries {
            fields.push(format!("\"maxDeliveries\":{v}"));
        }
        format!("{{{}}}", fields.join(","))
    }
}

/// A `PATCH` field that accepts going back to the server default (`null`).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum Nullable<T> {
    /// Does not send the field.
    #[default]
    Keep,
    /// Sends `null`: goes back to the server default.
    Default,
    Set(T),
}

impl<T: fmt::Display> Nullable<T> {
    fn push(&self, name: &str, fields: &mut Vec<String>) {
        match self {
            Nullable::Keep => {}
            Nullable::Default => fields.push(format!("\"{name}\":null")),
            Nullable::Set(v) => fields.push(format!("\"{name}\":{v}")),
        }
    }
}

/// `PATCH /topics/{topic}`: only what was filled in is sent.
#[derive(Debug, Clone, Default)]
pub struct TopicUpdate {
    /// Replaces the whole map (`Some(empty)` clears the tags).
    pub tags: Option<Vec<(String, String)>>,
    pub prefixes: Option<Vec<String>>,
    pub idle_timeout: Option<u64>,
    pub max_message_bytes: Nullable<u64>,
    pub ttl: Nullable<u64>,
    pub max_deliveries: Nullable<u64>,
}

impl TopicUpdate {
    pub fn to_json(&self) -> String {
        let mut fields = Vec::new();
        if let Some(tags) = &self.tags {
            fields.push(format!("\"tags\":{}", json_map(tags)));
        }
        if let Some(prefixes) = &self.prefixes {
            fields.push(format!("\"prefixes\":{}", json_list(prefixes)));
        }
        if let Some(v) = self.idle_timeout {
            fields.push(format!("\"idleTimeout\":{v}"));
        }
        self.max_message_bytes.push("maxMessageBytes", &mut fields);
        self.ttl.push("ttl", &mut fields);
        self.max_deliveries.push("maxDeliveries", &mut fields);
        format!("{{{}}}", fields.join(","))
    }
}

#[derive(Debug, Clone, Default)]
pub struct PublishOptions {
    /// Default `application/json`.
    pub content_type: Option<String>,
    pub group_id: Option<String>,
    pub deduplication_id: Option<String>,
    pub request_id: Option<String>,
    /// Set it when the topic is a FIFO queue: only there can `502`/`504` be retried.
    pub fifo: bool,
}

#[derive(Debug, Clone, Default)]
pub struct ConsumeOptions {
    pub max_messages: Option<u32>,
    pub visibility_timeout: Option<u32>,
    pub wait_time: Option<u32>,
    pub auto_create: bool,
    /// The next four only apply with `auto_create`.
    pub volatile: Option<bool>,
    pub idle_timeout: Option<u32>,
    pub fifo: Option<bool>,
    pub tags: Vec<(String, String)>,
    pub request_id: Option<String>,
}

fn segment(s: &str) -> String {
    http::percent_encode(s)
}

// ---------------------------------------------------------------------------------------------
// The nine operations
// ---------------------------------------------------------------------------------------------

impl Client {
    /// `POST /topics`.
    pub fn create_topic(&self, request: &TopicRequest) -> Result<Topic, Error> {
        let mut call = Call::new("POST", "/topics").json_body(request.to_json());
        call.recover = vec![(409, "topic.already-exists")];
        let reply = self.call(&call)?;
        if reply.recovered {
            return self.get_topic(&request.name);
        }
        Topic::parse(&reply.text())
    }

    /// `GET /topics/{topic}`.
    pub fn get_topic(&self, name: &str) -> Result<Topic, Error> {
        let reply = self.call(&Call::new("GET", format!("/topics/{}", segment(name))))?;
        Topic::parse(&reply.text())
    }

    /// `GET /topics`. Parameters that are `None` do not go in the query.
    pub fn list_topics(
        &self,
        limit: Option<u32>,
        cursor: Option<&str>,
        name: Option<&str>,
    ) -> Result<Page<Topic>, Error> {
        let mut call = Call::new("GET", "/topics");
        if let Some(limit) = limit {
            call = call.query("limit", limit);
        }
        if let Some(cursor) = cursor {
            call = call.query("cursor", cursor);
        }
        if let Some(name) = name {
            call = call.query("name", name);
        }
        parse_page(&self.call(&call)?.text(), Topic::parse)
    }

    /// All topics, page by page.
    pub fn list_all_topics(&self, name: Option<&str>) -> Result<Vec<Topic>, Error> {
        let mut all = Vec::new();
        let mut cursor: Option<String> = None;
        loop {
            let page = self.list_topics(None, cursor.as_deref(), name)?;
            all.extend(page.items);
            match page.next_cursor {
                Some(next) => cursor = Some(next),
                None => return Ok(all),
            }
        }
    }

    /// `PATCH /topics/{topic}`.
    pub fn update_topic(&self, name: &str, update: &TopicUpdate) -> Result<Topic, Error> {
        let call =
            Call::new("PATCH", format!("/topics/{}", segment(name))).json_body(update.to_json());
        Topic::parse(&self.call(&call)?.text())
    }

    /// `DELETE /topics/{topic}`.
    pub fn delete_topic(&self, name: &str) -> Result<(), Error> {
        let mut call = Call::new("DELETE", format!("/topics/{}", segment(name)));
        call.recover = vec![(404, "topic.not-found")];
        self.call(&call).map(|_| ())
    }

    /// `POST /topics/{topic}/messages`. The body goes as bytes, without validation.
    pub fn publish(
        &self,
        topic: &str,
        body: &[u8],
        options: &PublishOptions,
    ) -> Result<PublishResponse, Error> {
        let mut call = Call::new("POST", format!("/topics/{}/messages", segment(topic)));
        call.body = body.to_vec();
        call.content_type = Some(
            options
                .content_type
                .clone()
                .unwrap_or_else(|| "application/json".to_owned()),
        );
        if let Some(group) = &options.group_id {
            call = call.query("groupId", group);
        }
        if let Some(dedup) = &options.deduplication_id {
            call = call.query("deduplicationId", dedup);
        }
        call.request_id = options.request_id.clone();
        call.retry_gateway = options.fifo;
        // A publication with an empty body still needs a `Content-Type`: the body goes as it came.
        let raw = self.call(&call)?.text();
        let f = Fields::parse(&raw).map_err(|e| bad_response("publication", e))?;
        Ok(PublishResponse {
            id: f.string("id"),
            duplicate: f.boolean("duplicate"),
            matched: f.unsigned("matched"),
            raw,
        })
    }

    pub fn publish_json(&self, topic: &str, json_text: &str) -> Result<PublishResponse, Error> {
        self.publish(topic, json_text.as_bytes(), &PublishOptions::default())
    }

    pub fn publish_text(&self, topic: &str, text: &str) -> Result<PublishResponse, Error> {
        let options = PublishOptions {
            content_type: Some("text/plain; charset=utf-8".to_owned()),
            ..PublishOptions::default()
        };
        self.publish(topic, text.as_bytes(), &options)
    }

    /// `GET /topics/{topic}/messages`. The read time is `waitTime + 10 s`, not the
    /// `requestTimeout`.
    pub fn consume(&self, topic: &str, options: &ConsumeOptions) -> Result<Vec<Message>, Error> {
        let call = self.consume_call(topic, options);
        let raw = self.call(&call)?.text();
        let f = Fields::parse(&raw).map_err(|e| bad_response("consumo", e))?;
        json::array_items(f.raw("messages").unwrap_or("[]"))
            .map_err(|e| bad_response("messages", e))?
            .into_iter()
            .map(Message::parse)
            .collect()
    }

    pub fn consume_call(&self, topic: &str, options: &ConsumeOptions) -> Call {
        let mut call = Call::new("GET", format!("/topics/{}/messages", segment(topic)));
        if let Some(v) = options.max_messages {
            call = call.query("maxMessages", v);
        }
        if let Some(v) = options.visibility_timeout {
            call = call.query("visibilityTimeout", v);
        }
        if let Some(v) = options.wait_time {
            call = call.query("waitTime", v);
        }
        if options.auto_create {
            call = call.query("autoCreate", true);
            if let Some(v) = options.volatile {
                call = call.query("volatile", v);
            }
            if let Some(v) = options.idle_timeout {
                call = call.query("idleTimeout", v);
            }
            if let Some(v) = options.fifo {
                call = call.query("fifo", v);
            }
            for (k, v) in &options.tags {
                call = call.query(&format!("tag.{k}"), v);
            }
        }
        call.request_id = options.request_id.clone();
        call.timeout =
            Some(Duration::from_secs(u64::from(options.wait_time.unwrap_or(0))) + LONG_POLL_SLACK);
        call
    }

    /// `DELETE /topics/{topic}/messages/{id}?receiptToken=`.
    pub fn ack(&self, topic: &str, message_id: &str, receipt_token: &str) -> Result<(), Error> {
        let call = Call::new(
            "DELETE",
            format!(
                "/topics/{}/messages/{}",
                segment(topic),
                segment(message_id)
            ),
        )
        .query("receiptToken", receipt_token);
        self.call(&call).map(|_| ())
    }

    /// `PUT /topics/{topic}/messages/{id}/visibility?receiptToken=`.
    pub fn change_visibility(
        &self,
        topic: &str,
        message_id: &str,
        receipt_token: &str,
        seconds: u32,
    ) -> Result<VisibilityResponse, Error> {
        let call = Call::new(
            "PUT",
            format!(
                "/topics/{}/messages/{}/visibility",
                segment(topic),
                segment(message_id)
            ),
        )
        .query("receiptToken", receipt_token)
        .json_body(format!("{{\"visibilityTimeout\":{seconds}}}"));
        let raw = self.call(&call)?.text();
        let f = Fields::parse(&raw).map_err(|e| bad_response("invisibilidade", e))?;
        Ok(VisibilityResponse {
            id: f.string("id").unwrap_or_default(),
            invisible_until: f.string("invisibleUntil").unwrap_or_default(),
            raw,
        })
    }

    /// The consume loop (D71.1): long polling (`waitTime` 20 and one message at a time, if not
    /// set), calls the `handler` and acknowledges by itself **only if it returns `Ok`**. `stop` is
    /// checked before each consume and after each message; returning `true`, the loop ends.
    /// A server error while consuming or acknowledging propagates.
    pub fn subscribe<H, S>(
        &self,
        topic: &str,
        options: &ConsumeOptions,
        mut stop: S,
        mut handler: H,
    ) -> Result<(), Error>
    where
        H: FnMut(&Message) -> Result<(), Box<dyn std::error::Error>>,
        S: FnMut() -> bool,
    {
        let mut options = options.clone();
        options.wait_time.get_or_insert(20);
        options.max_messages.get_or_insert(1);
        while !stop() {
            for message in self.consume(topic, &options)? {
                if handler(&message).is_ok() {
                    match self.ack(topic, &message.id, &message.receipt_token) {
                        // The message already went back to the queue (deadline expired, `409`) or is already gone (`404`):
                        // there is nothing to acknowledge, and the loop goes on.
                        Err(e) if e.status == 409 || e.status == 404 => {}
                        other => other?,
                    }
                }
                if stop() {
                    return Ok(());
                }
            }
        }
        Ok(())
    }
}

mod handlers;
pub use handlers::{
    ConsumeError, Delivery, HandlerError, DEFAULT_MAX_MESSAGES, DEFAULT_VISIBILITY_TIMEOUT,
    DEFAULT_WAIT_TIME,
};

#[cfg(test)]
mod tests;