Split into several files and make more APIs

5 files changed, 495 insertions, 244 deletions

diff --git a/src/catalog.rs b/src/catalog.rs
new file mode 100644
index 0000000..952e99e
--- /dev/null
+++ b/src/catalog.rs
@@ -0,0 +1,230 @@
+use std::collections::HashMap;
+use std::fmt::Write;
+use std::sync::Arc;
+use std::time::Duration;
+
+use anyhow::Result;
+use futures::future::BoxFuture;
+use futures::stream::futures_unordered::FuturesUnordered;
+use futures::{FutureExt, StreamExt};
+use log::*;
+use serde::{Deserialize, Serialize};
+use tokio::select;
+use tokio::sync::watch;
+
+use crate::{Consul, WithIndex};
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "PascalCase")]
+pub struct ConsulNode {
+    pub node: String,
+    pub address: String,
+    pub meta: HashMap<String, String>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "PascalCase")]
+pub struct ConsulService {
+    pub service: String,
+    pub address: String,
+    pub port: u16,
+    pub tags: Vec<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "PascalCase")]
+pub struct ConsulCatalogNode {
+    pub node: ConsulNode,
+    pub services: HashMap<String, ConsulService>,
+}
+
+pub type ConsulServiceList = HashMap<String, Vec<String>>;
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "PascalCase")]
+pub struct ConsulServiceNode {
+    pub node: String,
+    pub address: String,
+    pub node_meta: HashMap<String, String>,
+    pub service_name: String,
+    pub service_tags: Vec<String>,
+    pub service_address: String,
+    pub service_port: u16,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "PascalCase")]
+pub struct ConsulHealthServiceNode {
+    pub node: ConsulNode,
+    pub service: ConsulService,
+    pub checks: Vec<ConsulHealthCheck>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "PascalCase")]
+pub struct ConsulHealthCheck {
+    pub node: String,
+    #[serde(rename = "CheckID")]
+    pub check_id: String,
+    pub name: String,
+    pub status: String,
+    pub output: String,
+    #[serde(rename = "Type")]
+    pub type_: String,
+}
+
+pub type AllServiceHealth = HashMap<String, Arc<[ConsulHealthServiceNode]>>;
+
+impl Consul {
+    pub async fn catalog_node_list(
+        &self,
+        last_index: Option<usize>,
+    ) -> Result<WithIndex<Vec<ConsulNode>>> {
+        self.get_with_index(format!("{}/v1/catalog/nodes", self.url), last_index)
+            .await
+    }
+
+    pub async fn catalog_node(
+        &self,
+        host: &str,
+        last_index: Option<usize>,
+    ) -> Result<WithIndex<Option<ConsulCatalogNode>>> {
+        self.get_with_index(format!("{}/v1/catalog/node/{}", self.url, host), last_index)
+            .await
+    }
+
+    pub async fn catalog_service_list(
+        &self,
+        last_index: Option<usize>,
+    ) -> Result<WithIndex<ConsulServiceList>> {
+        self.get_with_index::<ConsulServiceList>(
+            format!("{}/v1/catalog/services", self.url),
+            last_index,
+        )
+        .await
+    }
+
+    pub async fn catalog_service_nodes(
+        &self,
+        service: &str,
+        last_index: Option<usize>,
+    ) -> Result<WithIndex<Vec<ConsulServiceNode>>> {
+        self.get_with_index(
+            format!("{}/v1/catalog/service/{}", self.url, service),
+            last_index,
+        )
+        .await
+    }
+
+    pub async fn health_service_instances(
+        &self,
+        service: &str,
+        last_index: Option<usize>,
+    ) -> Result<WithIndex<Vec<ConsulHealthServiceNode>>> {
+        self.get_with_index(
+            format!("{}/v1/health/service/{}", self.url, service),
+            last_index,
+        )
+        .await
+    }
+
+    pub fn watch_all_service_health(&self) -> watch::Receiver<AllServiceHealth> {
+        let (tx, rx) = watch::channel(HashMap::new());
+
+        tokio::spawn(do_watch_all_service_health(self.clone(), tx));
+
+        rx
+    }
+
+    async fn get_with_index<T: for<'de> Deserialize<'de>>(
+        &self,
+        mut url: String,
+        last_index: Option<usize>,
+    ) -> Result<WithIndex<T>> {
+        if let Some(i) = last_index {
+            if url.contains('?') {
+                write!(&mut url, "&index={}", i).unwrap();
+            } else {
+                write!(&mut url, "?index={}", i).unwrap();
+            }
+        }
+        debug!("GET {} as {}", url, std::any::type_name::<T>());
+
+        let http = self.client.get(&url).send().await?;
+
+        Ok(WithIndex::<T>::index_from(&http)?.value(http.json().await?))
+    }
+}
+
+async fn do_watch_all_service_health(consul: Consul, tx: watch::Sender<AllServiceHealth>) {
+    let mut services = AllServiceHealth::new();
+    let mut service_watchers = FuturesUnordered::<BoxFuture<(String, Result<_>)>>::new();
+    let mut service_list: BoxFuture<Result<_>> = Box::pin(consul.catalog_service_list(None));
+
+    loop {
+        select! {
+            list_res = &mut service_list => {
+                match list_res {
+                    Ok(list) => {
+                        let list_index = list.index();
+                        for service in list.into_inner().keys() {
+                            if !services.contains_key(service) {
+                                services.insert(service.to_string(), Arc::new([]));
+
+                                let service = service.to_string();
+                                service_watchers.push(Box::pin(async {
+                                    let res = consul.health_service_instances(&service, None).await;
+                                    (service, res)
+                                }));
+                            }
+                        }
+                        service_list = Box::pin(consul.catalog_service_list(Some(list_index)));
+                    }
+                    Err(e) => {
+                        warn!("Error listing services: {}", e);
+                        service_list = Box::pin(async {
+                            tokio::time::sleep(Duration::from_secs(30)).await;
+                            consul.catalog_service_list(None).await
+                        });
+                    }
+                }
+            }
+            (service, watch_res) = service_watchers.next().then(some_or_pending) => {
+                match watch_res {
+                    Ok(nodes) => {
+                        let index = nodes.index();
+                        services.insert(service.clone(), nodes.into_inner().into());
+
+                        let consul = &consul;
+                        service_watchers.push(Box::pin(async move {
+                            let res = consul.health_service_instances(&service, Some(index)).await;
+                            (service, res)
+                        }));
+
+                        if tx.send(services.clone()).is_err() {
+                            break;
+                        }
+                    }
+                    Err(e) => {
+                        warn!("Error getting service {}: {}", service, e);
+                        service_watchers.push(Box::pin(async {
+                            tokio::time::sleep(Duration::from_secs(30)).await;
+                            let res = consul.health_service_instances(&service, None).await;
+                            (service, res)
+                        }));
+                    }
+                }
+            }
+            _ = tx.closed() => {
+                break;
+            }
+        }
+    }
+}
+
+async fn some_or_pending<T>(value: Option<T>) -> T {
+    match value {
+        Some(v) => v,
+        None => futures::future::pending().await,
+    }
+}
diff --git a/src/kv.rs b/src/kv.rs
new file mode 100644
index 0000000..6c6f15a
--- /dev/null
+++ b/src/kv.rs
@@ -0,0 +1,64 @@
+use anyhow::{anyhow, Result};
+use bytes::Bytes;
+use log::*;
+use reqwest::StatusCode;
+use serde::{Deserialize, Serialize};
+
+use crate::Consul;
+
+impl Consul {
+    pub async fn kv_get(&self, key: &str) -> Result<Option<Bytes>> {
+        debug!("kv_get {}", key);
+
+        let url = format!("{}/v1/kv/{}{}?raw", self.url, self.kv_prefix, key);
+        let http = self.client.get(&url).send().await?;
+        match http.status() {
+            StatusCode::OK => Ok(Some(http.bytes().await?)),
+            StatusCode::NOT_FOUND => Ok(None),
+            _ => Err(anyhow!(
+                "Consul request failed: {:?}",
+                http.error_for_status()
+            )),
+        }
+    }
+
+    pub async fn kv_get_json<T: for<'de> Deserialize<'de>>(&self, key: &str) -> Result<Option<T>> {
+        debug!("kv_get_json {}", key);
+
+        let url = format!("{}/v1/kv/{}{}?raw", self.url, self.kv_prefix, key);
+        let http = self.client.get(&url).send().await?;
+        match http.status() {
+            StatusCode::OK => Ok(Some(http.json().await?)),
+            StatusCode::NOT_FOUND => Ok(None),
+            _ => Err(anyhow!(
+                "Consul request failed: {:?}",
+                http.error_for_status()
+            )),
+        }
+    }
+
+    pub async fn kv_put(&self, key: &str, bytes: Bytes) -> Result<()> {
+        debug!("kv_put {}", key);
+
+        let url = format!("{}/v1/kv/{}{}", self.url, self.kv_prefix, key);
+        let http = self.client.put(&url).body(bytes).send().await?;
+        http.error_for_status()?;
+        Ok(())
+    }
+
+    pub async fn kv_put_json<T: Serialize>(&self, key: &str, value: &T) -> Result<()> {
+        debug!("kv_put_json {}", key);
+
+        let url = format!("{}/v1/kv/{}{}", self.url, self.kv_prefix, key);
+        let http = self.client.put(&url).json(value).send().await?;
+        http.error_for_status()?;
+        Ok(())
+    }
+
+    pub async fn kv_delete(&self, key: &str) -> Result<()> {
+        let url = format!("{}/v1/kv/{}{}", self.url, self.kv_prefix, key);
+        let http = self.client.delete(&url).send().await?;
+        http.error_for_status()?;
+        Ok(())
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 8a9ad53..6326fa0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,258 +1,75 @@
-use std::collections::HashMap;
+mod catalog;
+mod kv;
+mod locking;
+mod with_index;
+
 use std::fs::File;
 use std::io::Read;
 
-use anyhow::{anyhow, bail, Result};
-use bytes::Bytes;
-use log::*;
-use reqwest::StatusCode;
-use serde::{Deserialize, Serialize};
-
-pub struct ConsulConfig {
-	pub addr: String,
-	pub ca_cert: Option<String>,
-	pub tls_skip_verify: bool,
-	pub client_cert: Option<String>,
-	pub client_key: Option<String>,
-}
-
-// ---- Watch and retrieve Consul catalog ----
-//
-#[derive(Serialize, Deserialize, Debug)]
-pub struct ConsulNode {
-	#[serde(rename = "Node")]
-	pub node: String,
-	#[serde(rename = "Address")]
-	pub address: String,
-	#[serde(rename = "Meta")]
-	pub meta: HashMap<String, String>,
-}
-
-#[derive(Serialize, Deserialize, Debug)]
-pub struct ConsulServiceEntry {
-	#[serde(rename = "Service")]
-	pub service: String,
-
-	#[serde(rename = "Address")]
-	pub address: String,
-
-	#[serde(rename = "Port")]
-	pub port: u16,
-
-	#[serde(rename = "Tags")]
-	pub tags: Vec<String>,
-}
-
-#[derive(Serialize, Deserialize, Debug)]
-pub struct ConsulNodeCatalog {
-	#[serde(rename = "Node")]
-	pub node: ConsulNode,
-	#[serde(rename = "Services")]
-	pub services: HashMap<String, ConsulServiceEntry>,
-}
+use anyhow::{bail, Result};
 
-// ---- Consul session management ----
+pub use with_index::WithIndex;
 
-#[derive(Serialize, Deserialize, Debug)]
-pub struct ConsulSessionRequest {
-	#[serde(rename = "Name")]
-	pub name: String,
-
-	#[serde(rename = "Node")]
-	pub node: Option<String>,
-
-	#[serde(rename = "LockDelay")]
-	pub lock_delay: Option<String>,
-
-	#[serde(rename = "TTL")]
-	pub ttl: Option<String>,
-
-	#[serde(rename = "Behavior")]
-	pub behavior: Option<String>,
-}
-
-#[derive(Serialize, Deserialize, Debug)]
-pub struct ConsulSessionResponse {
-	#[serde(rename = "ID")]
-	pub id: String,
+pub struct ConsulConfig {
+    pub addr: String,
+    pub ca_cert: Option<String>,
+    pub tls_skip_verify: bool,
+    pub client_cert: Option<String>,
+    pub client_key: Option<String>,
 }
 
 #[derive(Clone)]
 pub struct Consul {
-	client: reqwest::Client,
+    client: reqwest::Client,
 
-	url: String,
-	kv_prefix: String,
+    url: String,
+    kv_prefix: String,
 }
 
 impl Consul {
-	pub fn new(config: ConsulConfig, kv_prefix: &str) -> Result<Self> {
-		let client = match (&config.client_cert, &config.client_key) {
-			(Some(client_cert), Some(client_key)) => {
-				let mut client_cert_buf = vec![];
-				File::open(client_cert)?.read_to_end(&mut client_cert_buf)?;
-
-				let mut client_key_buf = vec![];
-				File::open(client_key)?.read_to_end(&mut client_key_buf)?;
-
-				let identity = reqwest::Identity::from_pem(
-					&[&client_cert_buf[..], &client_key_buf[..]].concat()[..],
-				)?;
-
-				if config.tls_skip_verify {
-					reqwest::Client::builder()
-						.use_rustls_tls()
-						.danger_accept_invalid_certs(true)
-						.identity(identity)
-						.build()?
-				} else if let Some(ca_cert) = &config.ca_cert {
-					let mut ca_cert_buf = vec![];
-					File::open(ca_cert)?.read_to_end(&mut ca_cert_buf)?;
-
-					reqwest::Client::builder()
-						.use_rustls_tls()
-						.add_root_certificate(reqwest::Certificate::from_pem(&ca_cert_buf[..])?)
-						.identity(identity)
-						.build()?
-				} else {
-					reqwest::Client::builder()
-						.use_rustls_tls()
-						.identity(identity)
-						.build()?
-				}
-			}
-			(None, None) => reqwest::Client::new(),
-			_ => bail!("Incomplete Consul TLS configuration parameters"),
-		};
-
-		Ok(Self {
-			client,
-			url: config.addr.trim_end_matches('/').to_string(),
-			kv_prefix: kv_prefix.to_string(),
-		})
-	}
-
-	pub async fn list_nodes(&self) -> Result<Vec<ConsulNode>> {
-		debug!("list_nodes");
-
-		let url = format!("{}/v1/catalog/nodes", self.url);
-
-		let http = self.client.get(&url).send().await?;
-		let resp: Vec<ConsulNode> = http.json().await?;
-		Ok(resp)
-	}
-
-	pub async fn watch_node(
-		&self,
-		host: &str,
-		idx: Option<usize>,
-	) -> Result<(Option<ConsulNodeCatalog>, usize)> {
-		debug!("watch_node {} {:?}", host, idx);
-
-		let url = match idx {
-			Some(i) => format!("{}/v1/catalog/node/{}?index={}", self.url, host, i),
-			None => format!("{}/v1/catalog/node/{}", self.url, host),
-		};
-
-		let http = self.client.get(&url).send().await?;
-		let new_idx = match http.headers().get("X-Consul-Index") {
-			Some(v) => v.to_str()?.parse::<usize>()?,
-			None => bail!("X-Consul-Index header not found"),
-		};
-
-		let resp: Option<ConsulNodeCatalog> = http.json().await?;
-		Ok((resp, new_idx))
-	}
-
-	// ---- KV get and put ----
-
-	pub async fn kv_get(&self, key: &str) -> Result<Option<Bytes>> {
-		debug!("kv_get {}", key);
-
-		let url = format!("{}/v1/kv/{}{}?raw", self.url, self.kv_prefix, key);
-		let http = self.client.get(&url).send().await?;
-		match http.status() {
-			StatusCode::OK => Ok(Some(http.bytes().await?)),
-			StatusCode::NOT_FOUND => Ok(None),
-			_ => Err(anyhow!(
-				"Consul request failed: {:?}",
-				http.error_for_status()
-			)),
-		}
-	}
-
-	pub async fn kv_get_json<T: for<'de> Deserialize<'de>>(&self, key: &str) -> Result<Option<T>> {
-		debug!("kv_get_json {}", key);
-
-		let url = format!("{}/v1/kv/{}{}?raw", self.url, self.kv_prefix, key);
-		let http = self.client.get(&url).send().await?;
-		match http.status() {
-			StatusCode::OK => Ok(Some(http.json().await?)),
-			StatusCode::NOT_FOUND => Ok(None),
-			_ => Err(anyhow!(
-				"Consul request failed: {:?}",
-				http.error_for_status()
-			)),
-		}
-	}
-
-	pub async fn kv_put(&self, key: &str, bytes: Bytes) -> Result<()> {
-		debug!("kv_put {}", key);
-
-		let url = format!("{}/v1/kv/{}{}", self.url, self.kv_prefix, key);
-		let http = self.client.put(&url).body(bytes).send().await?;
-		http.error_for_status()?;
-		Ok(())
-	}
-
-	pub async fn kv_put_json<T: Serialize>(&self, key: &str, value: &T) -> Result<()> {
-		debug!("kv_put_json {}", key);
-
-		let url = format!("{}/v1/kv/{}{}", self.url, self.kv_prefix, key);
-		let http = self.client.put(&url).json(value).send().await?;
-		http.error_for_status()?;
-		Ok(())
-	}
-
-	pub async fn kv_delete(&self, key: &str) -> Result<()> {
-		let url = format!("{}/v1/kv/{}{}", self.url, self.kv_prefix, key);
-		let http = self.client.delete(&url).send().await?;
-		http.error_for_status()?;
-		Ok(())
-	}
-
-	// ---- Locking ----
-
-	pub async fn create_session(&self, req: &ConsulSessionRequest) -> Result<String> {
-		debug!("create_session {:?}", req);
-
-		let url = format!("{}/v1/session/create", self.url);
-		let http = self.client.put(&url).json(req).send().await?;
-		let resp: ConsulSessionResponse = http.json().await?;
-		Ok(resp.id)
-	}
-
-	pub async fn acquire(&self, key: &str, bytes: Bytes, session: &str) -> Result<bool> {
-		debug!("acquire {}", key);
-
-		let url = format!(
-			"{}/v1/kv/{}{}?acquire={}",
-			self.url, self.kv_prefix, key, session
-		);
-		let http = self.client.put(&url).body(bytes).send().await?;
-		let resp: bool = http.json().await?;
-		Ok(resp)
-	}
-
-	pub async fn release(&self, key: &str, bytes: Bytes, session: &str) -> Result<()> {
-		debug!("release {}", key);
-
-		let url = format!(
-			"{}/v1/kv/{}{}?release={}",
-			self.url, self.kv_prefix, key, session
-		);
-		let http = self.client.put(&url).body(bytes).send().await?;
-		http.error_for_status()?;
-		Ok(())
-	}
+    pub fn new(config: ConsulConfig, kv_prefix: &str) -> Result<Self> {
+        let client = match (&config.client_cert, &config.client_key) {
+            (Some(client_cert), Some(client_key)) => {
+                let mut client_cert_buf = vec![];
+                File::open(client_cert)?.read_to_end(&mut client_cert_buf)?;
+
+                let mut client_key_buf = vec![];
+                File::open(client_key)?.read_to_end(&mut client_key_buf)?;
+
+                let identity = reqwest::Identity::from_pem(
+                    &[&client_cert_buf[..], &client_key_buf[..]].concat()[..],
+                )?;
+
+                if config.tls_skip_verify {
+                    reqwest::Client::builder()
+                        .use_rustls_tls()
+                        .danger_accept_invalid_certs(true)
+                        .identity(identity)
+                        .build()?
+                } else if let Some(ca_cert) = &config.ca_cert {
+                    let mut ca_cert_buf = vec![];
+                    File::open(ca_cert)?.read_to_end(&mut ca_cert_buf)?;
+
+                    reqwest::Client::builder()
+                        .use_rustls_tls()
+                        .add_root_certificate(reqwest::Certificate::from_pem(&ca_cert_buf[..])?)
+                        .identity(identity)
+                        .build()?
+                } else {
+                    reqwest::Client::builder()
+                        .use_rustls_tls()
+                        .identity(identity)
+                        .build()?
+                }
+            }
+            (None, None) => reqwest::Client::new(),
+            _ => bail!("Incomplete Consul TLS configuration parameters"),
+        };
+
+        Ok(Self {
+            client,
+            url: config.addr.trim_end_matches('/').to_string(),
+            kv_prefix: kv_prefix.to_string(),
+        })
+    }
 }
diff --git a/src/locking.rs b/src/locking.rs
new file mode 100644
index 0000000..12e9ac0
--- /dev/null
+++ b/src/locking.rs
@@ -0,0 +1,65 @@
+use anyhow::Result;
+use bytes::Bytes;
+use log::*;
+use serde::{Deserialize, Serialize};
+
+use crate::Consul;
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct ConsulSessionRequest {
+    #[serde(rename = "Name")]
+    pub name: String,
+
+    #[serde(rename = "Node")]
+    pub node: Option<String>,
+
+    #[serde(rename = "LockDelay")]
+    pub lock_delay: Option<String>,
+
+    #[serde(rename = "TTL")]
+    pub ttl: Option<String>,
+
+    #[serde(rename = "Behavior")]
+    pub behavior: Option<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct ConsulSessionResponse {
+    #[serde(rename = "ID")]
+    pub id: String,
+}
+
+impl Consul {
+    pub async fn create_session(&self, req: &ConsulSessionRequest) -> Result<String> {
+        debug!("create_session {:?}", req);
+
+        let url = format!("{}/v1/session/create", self.url);
+        let http = self.client.put(&url).json(req).send().await?;
+        let resp: ConsulSessionResponse = http.json().await?;
+        Ok(resp.id)
+    }
+
+    pub async fn acquire(&self, key: &str, bytes: Bytes, session: &str) -> Result<bool> {
+        debug!("acquire {}", key);
+
+        let url = format!(
+            "{}/v1/kv/{}{}?acquire={}",
+            self.url, self.kv_prefix, key, session
+        );
+        let http = self.client.put(&url).body(bytes).send().await?;
+        let resp: bool = http.json().await?;
+        Ok(resp)
+    }
+
+    pub async fn release(&self, key: &str, bytes: Bytes, session: &str) -> Result<()> {
+        debug!("release {}", key);
+
+        let url = format!(
+            "{}/v1/kv/{}{}?release={}",
+            self.url, self.kv_prefix, key, session
+        );
+        let http = self.client.put(&url).body(bytes).send().await?;
+        http.error_for_status()?;
+        Ok(())
+    }
+}
diff --git a/src/with_index.rs b/src/with_index.rs
new file mode 100644
index 0000000..90e06be
--- /dev/null
+++ b/src/with_index.rs
@@ -0,0 +1,75 @@
+use std::fmt::{Debug, Display};
+
+use anyhow::{bail, Result};
+use reqwest::Response;
+
+pub struct WithIndex<T> {
+    value: T,
+    index: usize,
+}
+
+impl<T> WithIndex<T> {
+    pub fn index_from(resp: &Response) -> Result<WithIndexBuilder<T>> {
+        let index = match resp.headers().get("X-Consul-Index") {
+            Some(v) => v.to_str()?.parse::<usize>()?,
+            None => bail!("X-Consul-Index header not found"),
+        };
+        Ok(WithIndexBuilder {
+            index,
+            _phantom: Default::default(),
+        })
+    }
+
+    pub fn into_inner(self) -> T {
+        self.value
+    }
+
+    pub fn index(&self) -> usize {
+        self.index
+    }
+}
+
+impl<T> std::convert::AsRef<T> for WithIndex<T> {
+    fn as_ref(&self) -> &T {
+        &self.value
+    }
+}
+
+impl<T> std::borrow::Borrow<T> for WithIndex<T> {
+    fn borrow(&self) -> &T {
+        &self.value
+    }
+}
+
+impl<T> std::ops::Deref for WithIndex<T> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        &self.value
+    }
+}
+
+impl<T: Debug> Debug for WithIndex<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        <T as Debug>::fmt(self, f)
+    }
+}
+
+impl<T: Display> Display for WithIndex<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        <T as Display>::fmt(self, f)
+    }
+}
+
+pub struct WithIndexBuilder<T> {
+    _phantom: std::marker::PhantomData<T>,
+    index: usize,
+}
+
+impl<T> WithIndexBuilder<T> {
+    pub fn value(self, value: T) -> WithIndex<T> {
+        WithIndex {
+            value,
+            index: self.index,
+        }
+    }
+}