fix: order the catalogs

Fixes #5

app/catalog.json

@@ -9,21 +9,24 @@
       "rel": "child",
       "type": "application/json",
       "title": "Microsoft Planetary Computer",
-      "heystac:id": "microsoft-pc"
+      "heystac:id": "microsoft-pc",
+      "heystac:index": 0
     },
     {
-      "href": "https://landsatlook.usgs.gov/stac-server",
+      "href": "https://earth-search.aws.element84.com/v1",
       "rel": "child",
       "type": "application/json",
-      "title": "USGS Landsat",
-      "heystac:id": "usgs-landsat"
+      "title": "Earth Search by Element 84",
+      "heystac:id": "earth-search-aws",
+      "heystac:index": 1
     },
     {
-      "href": "https://earth-search.aws.element84.com/v1",
+      "href": "https://landsatlook.usgs.gov/stac-server",
       "rel": "child",
       "type": "application/json",
-      "title": "Earth Search by Element 84",
-      "heystac:id": "earth-search-aws"
+      "title": "USGS Landsat",
+      "heystac:id": "usgs-landsat",
+      "heystac:index": 2
     }
   ]
 }

config.toml

@@ -1,11 +1,14 @@
 [catalogs.microsoft-pc]
 href = "https://planetarycomputer.microsoft.com/api/stac/v1"
 title = "Microsoft Planetary Computer"
+index = 0
 
 [catalogs.earth-search-aws]
 href = "https://earth-search.aws.element84.com/v1"
 title = "Earth Search by Element 84"
+index = 1
 
 [catalogs.usgs-landsat]
 href = "https://landsatlook.usgs.gov/stac-server"
 title = "USGS Landsat"
+index = 2

src/lib.rs

@@ -20,6 +20,7 @@ pub struct Config {
 struct CatalogConfig {
     href: String,
     title: String,
+    index: usize,
 }
 
 impl Config {
@@ -37,8 +38,17 @@ impl Config {
                 Link::child(&catalog_config.href).title(Some(catalog_config.title.clone()));
             link.additional_fields
                 .insert("heystac:id".into(), id.as_str().into());
+            link.additional_fields
+                .insert("heystac:index".into(), catalog_config.index.into());
             catalog.links.push(link);
         }
+        catalog.links.sort_by_key(|c| {
+            c.additional_fields
+                .get("heystac:index")
+                .unwrap()
+                .as_i64()
+                .unwrap()
+        });
         let file = File::create(path)?;
         serde_json::to_writer_pretty(file, &catalog).map_err(Error::from)
     }