chore: update and automatically install premake5

generate.sh

@@ -1,7 +1,71 @@
 #!/bin/bash
 
+PREMAKE_URL='https://github.com/premake/premake-core/releases/download/v5.0.0-beta4/premake-5.0.0-beta4-linux.tar.gz'
+PREMAKE_HASH='4356ab7cdec6085183d68fb240089376eacdc2fb751ffbd8063d797ae43abeb3'
+
+function install_premake {
+    if [[ ! -x "$(command -v wget)" ]]; then
+        echo "Failed: Installation requires wget" >&2
+        exit 2
+    fi
+    if [[ ! -x "$(command -v tar)" ]]; then
+        echo "Failed: Installation requires tar" >&2
+        exit 2
+    fi
+    if [[ ! -x "$(command -v sha256sum)" ]]; then
+        echo "Failed: Installation requires sha256sum" >&2
+        exit 2
+    fi
+
+    mkdir -p build
+    wget -nd -O build/premake.tar.gz "$PREMAKE_URL"
+    if [[ $? -ne 0 ]]; then
+        echo "Download failed" >&2
+        exit 2
+    fi
+
+    tar -xf build/premake.tar.gz -C build
+    if [[ $? -ne 0 ]]; then
+        echo "Extraction failed" >&2
+        exit 2
+    fi
+
+    rm build/premake.tar.gz
+
+    echo "${PREMAKE_HASH} build/premake5" | sha256sum -c
+    if [[ $? -ne 0 ]]; then
+        echo "Hash verification failed" >&2
+        rm build/premake5
+        exit 2
+    fi
+
+    chmod +x build/premake5
+}
+
 # Go to repository root
 cd "$(dirname "$0")" || exit 2
 
+if [[ ! -d ".git" ]]; then
+    echo "You must clone the OpenAssetTools repository using 'git clone'. Please read README.md." >&2
+    exit 1
+fi
+
+PREMAKE_BIN=''
+if [[ -x "$(command -v premake5)" ]]; then
+    PREMAKE_BIN='premake5'
+elif [[ -x "$(command -v build/premake5)" ]]; then
+    PREMAKE_BIN='build/premake5'
+else
+    echo "Could not find premake5. You can either install it yourself or this script download it for you."
+    if [[ "$(read -e -p 'Do you wish to download it automatically? [y/N]> '; echo $REPLY)" == [Yy]* ]]; then
+        echo "Installing premake"
+        install_premake
+        PREMAKE_BIN='build/premake5'
+    else
+        echo "Please install premake5 and try again"
+        exit 1
+    fi
+fi
+
 git submodule update --init --recursive
-tools/premake5 $@ gmake2
+$PREMAKE_BIN $@ gmake2