[PATCH proxmox-yew-comp v4 04/12] rrd: add rrd_value_renderer module

[Lukas Wagner <l.wagner@proxmox.com>]

This new module houses a couple of helpers that are commonly used
when rendering values in RRD graphs.

Signed-off-by: Lukas Wagner <l.wagner@proxmox.com>
---
 src/lib.rs                    |  2 +-
 src/rrd/mod.rs                |  2 +
 src/rrd/rrd_value_renderer.rs | 84 +++++++++++++++++++++++++++++++++++
 3 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100644 src/rrd/rrd_value_renderer.rs

diff --git a/src/lib.rs b/src/lib.rs
index 62aa571..2b09bf4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -124,7 +124,7 @@ pub use role_selector::RoleSelector;
 #[cfg(feature = "rrd")]
 mod rrd;
 #[cfg(feature = "rrd")]
-pub use rrd::{RRDGraph, Series};
+pub use rrd::{rrd_value_renderer, RRDGraph, Series};
 
 #[cfg(feature = "rrd")]
 mod rrd_grid;
diff --git a/src/rrd/mod.rs b/src/rrd/mod.rs
index 5bcc9be..031505d 100644
--- a/src/rrd/mod.rs
+++ b/src/rrd/mod.rs
@@ -9,3 +9,5 @@ pub(crate) mod series;
 pub use series::Series;
 
 pub(crate) mod units;
+
+pub mod rrd_value_renderer;
diff --git a/src/rrd/rrd_value_renderer.rs b/src/rrd/rrd_value_renderer.rs
new file mode 100644
index 0000000..d7ba3c4
--- /dev/null
+++ b/src/rrd/rrd_value_renderer.rs
@@ -0,0 +1,84 @@
+//! Helpers for rendering values in RRD graphs.
+
+/// Render CPU usage in percent. `v` is multiplied by 100 to get the percent value.
+pub fn render_cpu_usage(v: &f64) -> String {
+    if v.is_finite() {
+        format!("{:.1}%", v * 100.0)
+    } else {
+        v.to_string()
+    }
+}
+
+/// Render server load value.
+pub fn render_load(v: &f64) -> String {
+    if v.is_finite() {
+        format!("{:.2}", v)
+    } else {
+        v.to_string()
+    }
+}
+
+/// Render a byte value.
+pub fn render_bytes(v: &f64) -> String {
+    if v.is_finite() {
+        proxmox_human_byte::HumanByte::from(*v as u64).to_string()
+    } else {
+        v.to_string()
+    }
+}
+
+/// Render bandwidth.
+pub fn render_bandwidth(v: &f64) -> String {
+    if v.is_finite() {
+        let bytes = proxmox_human_byte::HumanByte::from(*v as u64);
+        format!("{bytes}/s")
+    } else {
+        v.to_string()
+    }
+}
+
+/// Render pressure stall value.
+pub fn render_pressure(v: &f64) -> String {
+    if v.is_finite() {
+        format!("{:.1}%", v)
+    } else {
+        v.to_string()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_render_cpu_usage() {
+        assert_eq!(render_cpu_usage(&0.532), "53.2%");
+        assert_eq!(render_cpu_usage(&f64::NAN), "NaN");
+    }
+
+    #[test]
+    fn test_render_load() {
+        assert_eq!(render_load(&0.538), "0.54");
+        assert_eq!(render_load(&f64::NAN), "NaN");
+    }
+
+    #[test]
+    fn test_render_bytes() {
+        assert_eq!(render_bytes(&(1024f64 * 1024f64)), "1 MiB");
+        assert_eq!(render_bytes(&(1254f64 * 1024f64)), "1.225 MiB");
+        assert_eq!(render_bytes(&f64::NAN), "NaN");
+    }
+
+    #[test]
+    fn test_render_bandwidth() {
+        assert_eq!(render_bandwidth(&(1024f64 * 1024f64)), "1 MiB/s");
+        assert_eq!(render_bandwidth(&(1254f64 * 1024f64)), "1.225 MiB/s");
+        assert_eq!(render_bandwidth(&f64::NAN), "NaN");
+    }
+
+    #[test]
+    fn test_render_pressure() {
+        assert_eq!(render_pressure(&0.538), "0.5%");
+        assert_eq!(render_pressure(&f64::NAN), "NaN");
+    }
+}
-- 
2.47.3