Make 'rustup target add *' to Gradle tasks

Signed-off-by: Hui-Hong You <hiroshi@ghostsinthelab.org>

Author: hiroshiyui

README.md

@@ -6,14 +6,6 @@ The libchewingAndroidAppModule is a byproduct of the [Guileless Bopomofo](https:
 
 libchewingAndroidAppModule 是[樸實注音鍵盤](https://github.com/hiroshiyui/GuilelessBopomofo)專案的副產品，將[新酷音函式庫](https://github.com/chewing/libchewing)打包為 Android App Module (AAR) 格式，透過模組化途徑方便開發與元件再利用。
 
-# Prerequisites for Rust targets 編譯 Rust 程式碼的必備項目
-
-* [rustup](https://rustup.rs/) - installer for the systems programming language Rust
-* `rustup target add aarch64-linux-android`
-* `rustup target add armv7-linux-androideabi`
-* `rustup target add i686-linux-android`
-* `rustup target add x86_64-linux-android`
-
 # Build 組建
 
 1. `git clone --recursive https://github.com/hiroshiyui/libchewingAndroidAppModule.git`

app/build.gradle.kts

@@ -99,8 +99,74 @@ android {
         }
     }
 
+    tasks.register<Exec>("rustupTargetAddAarch64LinuxAndroid") {
+        onlyIf {
+            try {
+                val result = exec {
+                    isIgnoreExitValue = true
+                    commandLine("rustup", "-V")
+                }
+                result.exitValue != 0
+            } catch (e: Exception) {
+                return@onlyIf false
+            }
+        }
+        commandLine("rustup", "target", "add", "aarch64-linux-android")
+    }
+
+    tasks.register<Exec>("rustupTargetAddArmv7LinuxAndroideabi") {
+        onlyIf {
+            try {
+                val result = exec {
+                    isIgnoreExitValue = true
+                    commandLine("rustup", "-V")
+                }
+                result.exitValue != 0
+            } catch (e: Exception) {
+                return@onlyIf false
+            }
+        }
+        commandLine("rustup", "target", "add", "armv7-linux-androideabi")
+    }
+
+    tasks.register<Exec>("rustupTargetAddI686LinuxAndroid") {
+        onlyIf {
+            try {
+                val result = exec {
+                    isIgnoreExitValue = true
+                    commandLine("rustup", "-V")
+                }
+                result.exitValue != 0
+            } catch (e: Exception) {
+                return@onlyIf false
+            }
+        }
+        commandLine("rustup", "target", "add", "i686-linux-android")
+    }
+
+    tasks.register<Exec>("rustupTargetAddX64LinuxAndroid") {
+        onlyIf {
+            try {
+                val result = exec {
+                    isIgnoreExitValue = true
+                    commandLine("rustup", "-V")
+                }
+                result.exitValue != 0
+            } catch (e: Exception) {
+                return@onlyIf false
+            }
+        }
+        commandLine("rustup", "target", "add", "x86_64-linux-android")
+    }
+
     tasks.preBuild {
-        dependsOn("copyChewingDataFiles")
+        dependsOn(
+            "copyChewingDataFiles",
+            "rustupTargetAddAarch64LinuxAndroid",
+            "rustupTargetAddArmv7LinuxAndroideabi",
+            "rustupTargetAddI686LinuxAndroid",
+            "rustupTargetAddX64LinuxAndroid"
+        )
     }
 
     tasks.register<Delete>("cleanChewingDataFiles") {