setupenv: Add dependency check

setupenv.bashrc

@@ -51,4 +51,70 @@ if [ -f "$PROJECT_BASE_DIR/.localenv.bashrc" ]; then
     echo "Loaded local environment customizations."
 fi
 
-echo ">>> Done."
+echo ">>> Checking for dependencies..."
+MISSING_DEPS=0
+
+if command -v wget > /dev/null 2>&1; then
+    true
+else
+    if command -v curl > /dev/null 2>&1; then
+        true
+    else
+        echo "WARNING: `wget` or `curl` is needed to download some additional dependencies."
+        MISSING_DEPS=1
+    fi
+fi
+
+if command -v sha256sum > /dev/null 2>&1; then
+    true
+else
+    if command -v sha256 > /dev/null 2>&1; then
+        true
+    else
+        echo "WARNING: Coreutils `sha256sum` or a `sha256` as found on NetBSD is needed to verify downloaded files."
+        MISSING_DEPS=1
+    fi
+fi
+
+if command -v gzip > /dev/null 2>&1; then
+    true
+else
+    echo "WARNING: `gzip` is needed to decompress downloaded dependencies."
+    MISSING_DEPS=1
+fi
+
+if command -v tar > /dev/null 2>&1; then
+    true
+else
+    echo "WARNING: `tar` is needed to unpack downloaded dependencies."
+    MISSING_DEPS=1
+fi
+
+if command -v cmake > /dev/null 2>&1; then
+    true
+else
+    echo "WARNING: `cmake` is needed to build downloaded dependencies."
+    MISSING_DEPS=1
+fi
+
+if [ -z "$CXX" ]; then
+    if command -v c++ > /dev/null 2>&1; then
+        true
+    else
+        echo "WARNING: Your system does not appear to have a standard C++ compiler. If you have a C++ compiler installed, but not linked to `c++` on your PATH, set it manually using `CXX=/path/to/your/compiler`."
+        MISSING_DEPS=1
+    fi
+fi
+
+if command -v xxd > /dev/null 2>&1; then
+    true
+else
+    echo "WARNING: `xxd` is needed for some tool scripts."
+    MISSING_DEPS=1
+fi
+
+if [ "$MISSING_DEPS" -eq 0 ]; then
+    echo "All set."
+fi
+
+unset MISSING_DEPS