androidenv: support 5 years of Android APIs with images; test 10 without

Cut down on the number of system images that need to be fetched by just
supporting packages from the last 5 years. Still test the last 10 years
of APIs without images.

doc/languages-frameworks/android.section.md

···
   have an aarch64-linux compile).
 * `platformVersions` specifies which platform SDK versions should be included.
   It defaults to including only the latest API level, though you can add more.
+* `numLatestPlatformVersions` specifies how many of the latest API levels to include,
+  if you are using the default for `platformVersions`. It defaults to 1, though you can
+  increase this to, for example, 5 to get the last 5 years of Android API packages.
 * `minPlatformVersion` and `maxPlatformVersion` take priority over `platformVersions`
   if both are provided. Note that `maxPlatformVersion` always defaults to the latest
   Android SDK platform version, allowing you to specify `minPlatformVersion` to describe

pkgs/development/mobile/androidenv/compose-android-packages.nix

···
   emulatorVersion ? repo.latest.emulator,
   minPlatformVersion ? null,
   maxPlatformVersion ? coerceInt repo.latest.platforms,
+  numLatestPlatformVersions ? 1,
   platformVersions ?
     if minPlatformVersion != null && maxPlatformVersion != null then
       let
···
         lib.max minPlatformVersionInt maxPlatformVersionInt
       )
     else
-      map coerceInt [ repo.latest.platforms ],
+      let
+        minPlatformVersionInt = if minPlatformVersion == null then 1 else coerceInt minPlatformVersion;
+        latestPlatformVersionInt = lib.max minPlatformVersionInt (coerceInt repo.latest.platforms);
+        firstPlatformVersionInt = lib.max minPlatformVersionInt (
+          latestPlatformVersionInt - (lib.max 1 numLatestPlatformVersions) + 1
+        );
+      in
+      lib.range firstPlatformVersionInt latestPlatformVersionInt,
   includeSources ? false,
   includeSystemImages ? false,
   systemImageTypes ? [

pkgs/development/mobile/androidenv/default.nix

···
   };
 
   androidPkgs = composeAndroidPackages {
-    minPlatformVersion = 28;
+    # Support roughly the last 5 years of Android packages and system images by default in nixpkgs.
+    numLatestPlatformVersions = 5;
     includeEmulator = "if-supported";
     includeSystemImages = "if-supported";
     includeNDK = "if-supported";

pkgs/development/mobile/androidenv/examples/shell.nix

···
 
   androidComposition = androidEnv.composeAndroidPackages {
     includeSources = true;
-    includeSystemImages = true;
+    includeSystemImages = false;
     includeEmulator = "if-supported";
     includeNDK = "if-supported";
     useGoogleAPIs = true;
 
-    minPlatformVersion = 23;
+    # Make sure everything from the last decade works since we are not using system images.
+    numLatestPlatformVersions = 10;
 
     # If you want to use a custom repo JSON:
     # repoJson = ../repo.json;
···
 
   androidSdk = androidComposition.androidsdk;
   platformTools = androidComposition.platform-tools;
+  firstSdk = pkgs.lib.foldl' pkgs.lib.min 100 androidComposition.platformVersions;
   latestSdk = pkgs.lib.foldl' pkgs.lib.max 0 androidComposition.platformVersions;
   jdk = pkgs.jdk;
 in
···
             "extras;google;gcm"
           )
 
-          for x in $(seq 23 ${toString latestSdk}); do
+          for x in $(seq ${toString firstSdk} ${toString latestSdk}); do
             if [ $x -ne 34 ]; then
               # FIXME couldn't find platforms;android-34, even though it's in the correct directory!! sdkmanager's bug?!
               packages+=("platforms;android-$x")
             fi
             packages+=("sources;android-$x")
-            if [ $x -ge 28 ]; then
-              if [ $x -lt 34 ]; then
-                packages+=("system-images;android-$x;google_apis_playstore;x86_64")
-              else
-                packages+=("system-images;android-$x;google_apis;x86_64")
-              fi
-            fi
           done
 
           ${pkgs.lib.optionalString includeAuto ''packages+=("extras;google;auto")''}