Read version from resource instead of hard-coding it (#220)

* Read version from resource instead of hard-coding it

* Moving to stamping to extract the version from tag or default to commit hash

* Cleaning up workspace_status.sh

Author: naveenOnarayanan

.bazelrc

@@ -2,3 +2,6 @@ run -c opt --show_loading_progress=false --show_progress=false --ui_event_filter
 run:verbose -c dbg --show_loading_progress=true --show_progress=true --ui_event_filters=info,error,debug
 # https://github.com/mockito/mockito/issues/1879
 test --sandbox_tmpfs_path=/tmp
+
+# To allow stamping git tag for version.
+build --workspace_status_command=$(pwd)/workspace_status.sh

cli/BUILD

@@ -8,6 +8,17 @@ config_setting(
     },
 )
 
+genrule(
+    name = "version_file",
+    srcs = [],
+    outs = ["version"],
+    cmd_bash = """
+        version_tag=$$(grep ^STABLE_GIT_TAG bazel-out/stable-status.txt | cut -d' ' -f2); \
+        printf '%s' $$version_tag > $@;
+    """,
+    stamp = 1,
+)
+
 java_binary(
     name = "bazel-diff",
     jvm_flags = select({
@@ -22,6 +33,7 @@ java_binary(
 kt_jvm_library(
     name = "cli-lib",
     srcs = glob(["src/main/kotlin/**/*.kt"]),
+    resources = [":version_file"],
     deps = [
         "@bazel_diff_maven//:com_google_code_gson_gson",
         "@bazel_diff_maven//:com_google_guava_guava",

cli/src/main/kotlin/com/bazel_diff/cli/VersionProvider.kt

@@ -1,9 +1,16 @@
 package com.bazel_diff.cli
 
 import picocli.CommandLine.IVersionProvider
+import java.io.BufferedReader
+import java.io.InputStreamReader
 
 class VersionProvider : IVersionProvider {
     override fun getVersion(): Array<String> {
-        return arrayOf("7.0.0")
+        val classLoader = this::class.java.classLoader
+        val inputStream = classLoader.getResourceAsStream("cli/version")
+            ?: throw IllegalArgumentException("unknown version as version file not found in resources")
+
+        val version = BufferedReader(InputStreamReader(inputStream)).use { it.readText().trim() }
+        return arrayOf(version)
     }
 }

workspace_status.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+
+# Get the current Git tag or default to the commit hash
+echo "STABLE_GIT_TAG $(git describe --tags --abbrev=0 2>/dev/null || git rev-parse HEAD)"