Add get price task (#20)

* implement get price task

* let get_price task into metrics system

* update readme

* update description

README.md

@@ -20,6 +20,7 @@ This exporter has below custom metrics right now!
 | BridgedBalance | the specific token balance of reserving safe on source chain ( this metric displays with 6 digits as the fractional part so need to divide the metric value by 10 to the power of 6 ) |
 | BridgedSupply | the token supply total minted on the destination chain ( this metric displays with 6 digits as the fractional part so need to divide the metric value by 10 to the power of 6 ) |
 | NavtiveBalance | the native balance of reserving safe on source chain ( this metric displays with 6 digits as the fractional part so need to divide the metric value by 10 to the power of 6 ) |
+| GetPrice | the close price of the related currency pair from gate.io ( this metric displays with 6 digits as the fractional part so need to divide the metric value by 10 to the power of 6 ) |
 
 ## Installation
 

src/config.rs

@@ -75,6 +75,7 @@ pub(crate) enum TaskName {
     BridgedBalance,
     BridgedSupply,
     NativeBalance,
+    GetPrice,
 }
 
 impl Default for TaskName {

src/crawler.rs

@@ -97,6 +97,14 @@ impl Crawler {
                     target.extra_opts.clone(),
                     crate::tasks::native_balance,
                 ),
+                TaskName::GetPrice => Task::new(
+                    "get_price".to_string(),
+                    // in this case the host_addr is the currency_pair
+                    target.host_addr.clone(),
+                    metric,
+                    target.extra_opts.clone(),
+                    crate::tasks::get_price,
+                ),
             };
 
             tasks.push(Arc::new(task));

src/metrics.rs

@@ -127,6 +127,11 @@ where
                 "the native balance of reserving safe on source chain",
             )
             .context("new native_balance failed")?,
+            TaskName::GetPrice => GenericGauge::new(
+                "get_price",
+                "the close price of the related currency pair from gate.io",
+            )
+            .context("new get_price failed")?,
         };
 
         registry

src/tasks/get_price.rs

@@ -0,0 +1,81 @@
+// curl -H 'Accept: application/json' -X GET https://api.gateio.ws/api/v4/spot/candlesticks\?currency_pair\=FRA_USDT\&interval\=15m\&limit\=1
+// [[unix_timestamp, trading_volume, close_price, highest_price, lowest_price, open_price]]
+// [["1645749900","2839.79160470986265","0.01815","0.01897","0.01793","0.01889"]]
+use crate::config::ExtraOpts;
+
+use anyhow::{bail, Context, Result};
+use prometheus::core::Number;
+use serde_json::Value;
+
+pub(crate) fn get_price<N: Number>(pair: &str, _opts: &Option<ExtraOpts>) -> Result<N> {
+    // https://api.gateio.ws/api/v4/spot/candlesticks\?currency_pair\=FRA_USDT\&interval\=15m\&limit\=1
+    let path = format!(
+        "https://api.gateio.ws/api/v4/spot/candlesticks?interval=15m&limit=1&currency_pair={}",
+        pair
+    );
+
+    let data: Value = ureq::get(&path)
+        .set("Accept", "application/json")
+        .call()
+        .with_context(|| format!("requesting gate.io call failed, pair:{:?}", pair))?
+        .into_json()
+        .with_context(|| format!("requesting gate.io json failed, pair:{:?}", pair))?;
+
+    if !data.is_array() || !data[0].is_array() {
+        bail!(
+            "the data is not an array which is:{:?}, pair:{:?}",
+            data,
+            pair
+        )
+    }
+
+    let d = data
+        .as_array()
+        .with_context(|| format!("data as_array failed, data:{:?}, pair:{:?}", data, pair))?;
+
+    if d.len() != 1 {
+        bail!(
+            "first level of data length is not 1: data:{:?}, pair:{:?}",
+            data,
+            pair
+        );
+    }
+
+    let info = d[0]
+        .as_array()
+        .with_context(|| format!("info as_array failed, data:{:?}, pair:{:?}", data, pair))?;
+
+    if info.len() < 3 {
+        bail!(
+            "second level of data length is smaller than 3: data:{:?}, pair:{:?}",
+            data,
+            pair
+        );
+    }
+
+    let price = info[2].as_str().with_context(|| {
+        format!(
+            "close price as_str failed, price:{:?}, pair:{:?}",
+            info[2], pair
+        )
+    })?;
+
+    let price = price.parse::<f64>().with_context(|| {
+        format!(
+            "close price parse into f64 failed, price:{:?}, pair:{:?}",
+            price, pair,
+        )
+    })?;
+
+    Ok(N::from_i64((price * 1000000.0).round() as i64))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_get_price() {
+        assert!(get_price::<u64>("FRA_USDT", &None).is_ok())
+    }
+}

src/tasks/mod.rs

@@ -12,3 +12,5 @@ mod bridged_supply;
 pub(crate) use bridged_supply::bridged_supply;
 mod native_balance;
 pub(crate) use native_balance::native_balance;
+mod get_price;
+pub(crate) use get_price::get_price;

src/tasks/native_balance.rs

@@ -81,16 +81,6 @@ mod tests {
 
     #[test]
     fn test_native_balance() {
-        println!(
-            "{:?}",
-            native_balance::<u64>(
-                "https://data-seed-prebsc-1-s1.binance.org:8545",
-                &Some(ExtraOpts::NativeBalance {
-                    native_address: "0xae13d989dac2f0debff460ac112a837c89baa7cd".to_string(),
-                    decimal: 18,
-                }),
-            )
-        );
         assert!(native_balance::<u64>(
             "https://data-seed-prebsc-1-s1.binance.org:8545",
             &Some(ExtraOpts::NativeBalance {