working, but ugly

.gitignore

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+/target

Cargo.toml

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+[package]
+name = "ecb-exchange"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+clap = { version = "4.5.23", features = ["derive"] }
+quick-xml = { version = "0.37.2", features = ["async-tokio", "tokio"] }
+reqwest = "0.12.12"
+serde = { version = "1.0.217", features = ["derive", "rc"] }
+serde_json = "1.0.134"
+tokio = { version = "1.42.0", features = ["macros"] }

src/main.rs

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+use clap::{Parser, Subcommand};
+use quick_xml::events::Event;
+use quick_xml::Reader;
+use reqwest::Client;
+use serde::Serialize;
+use std::collections::HashMap;
+use std::error::Error;
+use std::fs;
+
+#[derive(Debug, Serialize)]
+pub struct ExchangeRateResult {
+    pub time: String,
+    pub rates: HashMap<String, f64>,
+}
+
+const ECB_DAILY: &'static str = "https://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml";
+const ECB_HIST_DAILY: &'static str = "https://www.ecb.europa.eu/stats/eurofxref/eurofxref-hist.xml";
+const ECB_HIST_90: &'static str =
+    "https://www.ecb.europa.eu/stats/eurofxref/eurofxref-hist-90d.xml";
+
+#[tokio::main(flavor = "current_thread")]
+async fn main() -> Result<(), Box<dyn Error>> {
+    let client = Client::new();
+    let xml_content = client.get(ECB_DAILY).send().await?.text().await?;
+    let parsed = parse(&xml_content).unwrap();
+    println!("{}", serde_json::to_string_pretty(&parsed).unwrap());
+    Ok(())
+}
+
+fn parse(xml: &str) -> Result<Vec<ExchangeRateResult>, Box<dyn Error>> {
+    let mut reader = Reader::from_str(xml);
+    reader.config_mut().trim_text(true);
+
+    let mut results = Vec::new();
+    let mut current_time: Option<String> = None;
+    let mut inside_cube_time = false;
+    let mut current_rates = HashMap::new();
+
+    fn handle_cube_element(
+        e: &quick_xml::events::BytesStart,
+        current_time: &mut Option<String>,
+        inside_cube_time: &mut bool,
+        current_rates: &mut HashMap<String, f64>,
+        results: &mut Vec<ExchangeRateResult>,
+    ) -> Result<(), Box<dyn Error>> {
+        if e.name().local_name().as_ref() != b"Cube" {
+            return Ok(());
+        }
+
+        let mut time_attr: Option<String> = None;
+        let mut currency_attr: Option<String> = None;
+        let mut rate_attr: Option<String> = None;
+
+        // Check attributes to see if it's a time-labeled Cube or a currency-labeled Cube
+        for attr_result in e.attributes() {
+            let attr = attr_result?;
+            let key = attr.key.as_ref();
+            let val = String::from_utf8_lossy(attr.value.as_ref()).to_string();
+
+            match key {
+                b"time" => {
+                    time_attr = Some(val);
+                }
+                b"currency" => {
+                    currency_attr = Some(val);
+                }
+                b"rate" => {
+                    rate_attr = Some(val);
+                }
+                _ => {}
+            }
+        }
+
+        // If we found a time attribute, it means we're at "Cube time='...'"
+        if let Some(t) = time_attr {
+            // If we already had a current_time, that means we finished one block
+            if current_time.is_some() {
+                let previous_time = current_time.take().unwrap();
+                results.push(ExchangeRateResult {
+                    time: previous_time,
+                    rates: current_rates.clone(),
+                });
+                current_rates.clear();
+            }
+            // Now set the new time
+            *current_time = Some(t);
+            *inside_cube_time = true;
+        }
+
+        // If we're inside an existing time block and we see currency/rate, store it
+        if *inside_cube_time {
+            if let (Some(c), Some(r_str)) = (currency_attr, rate_attr) {
+                let r = r_str.parse::<f64>()?;
+                current_rates.insert(c, r);
+            }
+        }
+
+        Ok(())
+    }
+
+    // Main parsing loop
+    while let Ok(event) = reader.read_event() {
+        match event {
+            // For normal (non-self-closing) <Cube> tags
+            Event::Start(e) => {
+                handle_cube_element(
+                    &e,
+                    &mut current_time,
+                    &mut inside_cube_time,
+                    &mut current_rates,
+                    &mut results,
+                )?;
+            }
+
+            // For self-closing <Cube .../> tags (like currency lines!)
+            Event::Empty(e) => {
+                handle_cube_element(
+                    &e,
+                    &mut current_time,
+                    &mut inside_cube_time,
+                    &mut current_rates,
+                    &mut results,
+                )?;
+            }
+            Event::Eof => break,
+            _ => {} // Event::End is here aswell
+        }
+    }
+
+    // If the document ended and we still have one block in memory
+    if let Some(last_time) = current_time {
+        results.push(ExchangeRateResult {
+            time: last_time,
+            rates: current_rates,
+        });
+    }
+
+    Ok(results)
+}