feat: async image conversion service (avif/webp) with backfill

crates/adapters/image-converter/src/config.rs

@@ -0,0 +1,90 @@
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum Format {
+    Avif,
+    Webp,
+}
+
+impl Format {
+    pub fn extension(self) -> &'static str {
+        match self {
+            Format::Avif => ".avif",
+            Format::Webp => ".webp",
+        }
+    }
+}
+
+pub struct ConversionConfig {
+    pub format: Format,
+}
+
+impl ConversionConfig {
+    pub fn from_env() -> anyhow::Result<Option<Self>> {
+        Self::from_vars(
+            std::env::var("IMAGE_CONVERSION_ENABLED").ok().as_deref(),
+            std::env::var("IMAGE_CONVERSION_FORMAT").ok().as_deref(),
+        )
+    }
+
+    fn from_vars(enabled: Option<&str>, format: Option<&str>) -> anyhow::Result<Option<Self>> {
+        if enabled != Some("true") {
+            return Ok(None);
+        }
+
+        let format_str = format.ok_or_else(|| {
+            anyhow::anyhow!("IMAGE_CONVERSION_FORMAT required when IMAGE_CONVERSION_ENABLED=true")
+        })?;
+
+        let format = match format_str {
+            "avif" => Format::Avif,
+            "webp" => Format::Webp,
+            other => anyhow::bail!(
+                "Unknown IMAGE_CONVERSION_FORMAT: {other:?}. Valid values: avif, webp"
+            ),
+        };
+
+        Ok(Some(Self { format }))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn disabled_by_default() {
+        assert!(ConversionConfig::from_vars(None, None).unwrap().is_none());
+        assert!(ConversionConfig::from_vars(Some("false"), None).unwrap().is_none());
+    }
+
+    #[test]
+    fn enabled_avif() {
+        let cfg = ConversionConfig::from_vars(Some("true"), Some("avif")).unwrap().unwrap();
+        assert_eq!(cfg.format, Format::Avif);
+    }
+
+    #[test]
+    fn enabled_webp() {
+        let cfg = ConversionConfig::from_vars(Some("true"), Some("webp")).unwrap().unwrap();
+        assert_eq!(cfg.format, Format::Webp);
+    }
+
+    #[test]
+    fn unknown_format_is_error() {
+        assert!(ConversionConfig::from_vars(Some("true"), Some("gif")).is_err());
+    }
+
+    #[test]
+    fn missing_format_when_enabled_is_error() {
+        assert!(ConversionConfig::from_vars(Some("true"), None).is_err());
+    }
+
+    #[test]
+    fn avif_extension() {
+        assert_eq!(Format::Avif.extension(), ".avif");
+    }
+
+    #[test]
+    fn webp_extension() {
+        assert_eq!(Format::Webp.extension(), ".webp");
+    }
+}