# Setup Java environment (JAVA_HOME, JDK_HOME, and PATH)
_setup_java() {
    [ -n "$ZSH_VERSION" ] && setopt localoptions nonomatch nullglob

    _is_valid_jre() {
        [ -n "$1" ] && [ -d "$1" ] && [ -x "$1/bin/java" ]
    }

    _is_valid_jdk() {
        _is_valid_jre "$1" && [ -x "$1/bin/javac" ]
    }

    _add_to_path() {
        [ -d "$1" ] || return 0
        case ":$PATH:" in
            *":$1:"*) ;;
            *) PATH="$1:$PATH"; export PATH ;;
        esac
    }

    # 1. If user already has a valid JAVA_HOME configured, respect it
    _has_user_jre=0
    if _is_valid_jre "${JAVA_HOME:-}"; then
        _has_user_jre=1
        _add_to_path "$JAVA_HOME/bin"
        if _is_valid_jdk "$JAVA_HOME"; then
            [ -z "$JDK_HOME" ] && export JDK_HOME="$JAVA_HOME"
        fi
    fi

    # If both a valid JRE (JAVA_HOME) and JDK (JDK_HOME) are already configured, we are done
    if [ "$_has_user_jre" -eq 1 ] && [ -n "$JDK_HOME" ] && _is_valid_jdk "$JDK_HOME"; then
        return 0
    fi

    # 2. Gather candidates across macOS and Linux
    _candidates=()

    # macOS tool: /usr/libexec/java_home
    if [ "$(uname -s 2>/dev/null)" = "Darwin" ] && [ -x "/usr/libexec/java_home" ]; then
        _jh=$(/usr/libexec/java_home 2>/dev/null)
        [ -n "$_jh" ] && _candidates+=("$_jh")
    fi

    # Linux tools: update-java-alternatives (Debian/Ubuntu) and readlink on java command
    if command -v update-java-alternatives >/dev/null 2>&1; then
        for _alt_path in $(update-java-alternatives -l 2>/dev/null | awk '{print $NF}'); do
            [ -d "$_alt_path" ] && _candidates+=("$_alt_path")
        done
    fi

    if command -v java >/dev/null 2>&1; then
        _java_bin=$(command -v java 2>/dev/null)
        if command -v readlink >/dev/null 2>&1; then
            _real_java=$(readlink -f "$_java_bin" 2>/dev/null)
            if [ -n "$_real_java" ] && [ -x "$_real_java" ]; then
                _alt_home="$(dirname "$(dirname "$_real_java")")"
                [ -n "$_alt_home" ] && _candidates+=("$_alt_home")
            fi
        fi
    fi

    # Cross-platform user managers (SDKMAN)
    [ -d "$HOME/.sdkman/candidates/java/current" ] && _candidates+=("$HOME/.sdkman/candidates/java/current")

    # macOS locations
    if [ "$(uname -s 2>/dev/null)" = "Darwin" ]; then
        # Homebrew OpenJDK
        for _d in /opt/homebrew/opt/openjdk/libexec/openjdk.jdk/Contents/Home \
                  /opt/homebrew/opt/openjdk@*/libexec/openjdk.jdk/Contents/Home \
                  /usr/local/opt/openjdk/libexec/openjdk.jdk/Contents/Home; do
            [ -d "$_d" ] && _candidates+=("$_d")
        done

        # Installed JVMs in /Library/Java/JavaVirtualMachines and ~/Library/...
        # Version-sorted descending to prefer newer releases
        for _d in $(
            for _jvm in /Library/Java/JavaVirtualMachines/*/Contents/Home \
                        "$HOME/Library/Java/JavaVirtualMachines"/*/Contents/Home; do
                [ -d "$_jvm" ] && echo "$_jvm"
            done | sort -V -r 2>/dev/null
        ); do
            _candidates+=("$_d")
        done

        # Android Studio bundled JBR/JDK
        for _d in \
            "/Applications/Android Studio.app/Contents/jbr/Contents/Home" \
            "/Applications/Android Studio.app/Contents/jre/Contents/Home" \
            "/Applications/Android Studio.app/Contents/jre/jdk/Contents/Home" \
            "$HOME/Applications/Android Studio.app/Contents/jbr/Contents/Home" \
            "$HOME/Applications/Android Studio.app/Contents/jre/Contents/Home"
        do
            [ -d "$_d" ] && _candidates+=("$_d")
        done
    fi

    # Linux / WSL locations
    if [ "$(uname -s 2>/dev/null)" = "Linux" ]; then
        # Default java symlink on Debian/Ubuntu
        [ -d "/usr/lib/jvm/default-java" ] && _candidates+=("/usr/lib/jvm/default-java")

        # Distribution JVMs in /usr/lib/jvm, version-sorted descending
        for _d in $(
            for _jvm in /usr/lib/jvm/*; do
                [ -d "$_jvm" ] && echo "$_jvm"
            done | sort -V -r 2>/dev/null
        ); do
            _candidates+=("$_d")
        done

        for _d in \
            "/usr/java/latest" \
            "/usr/java/default" \
            "/opt/android-studio/jbr" \
            "/opt/android-studio/jre" \
            "$HOME/android-studio/jbr" \
            "$HOME/.local/share/JetBrains/Toolbox/apps/android-studio/jbr"
        do
            [ -d "$_d" ] && _candidates+=("$_d")
        done
    fi

    # 3. Evaluate candidates: find best JRE (preferring SDK JREs) and best JDK
    _best_jdk=""
    _best_jre=""

    for _cand in "${_candidates[@]}"; do
        if [ -n "$_cand" ]; then
            if _is_valid_jdk "$_cand"; then
                [ -z "$_best_jdk" ] && _best_jdk="$_cand"
                [ -z "$_best_jre" ] && _best_jre="$_cand"
            elif _is_valid_jre "$_cand"; then
                [ -z "$_best_jre" ] && _best_jre="$_cand"
            fi
            if [ -n "$_best_jdk" ] && [ -n "$_best_jre" ]; then
                break
            fi
        fi
    done

    # 4. If no valid JAVA_HOME was set by user, configure it with best JRE (preferring SDK)
    if [ "$_has_user_jre" -eq 0 ] && [ -n "$_best_jre" ]; then
        export JAVA_HOME="$_best_jre"
        _add_to_path "$JAVA_HOME/bin"
    fi

    # 5. If no SDK/JDK_HOME is set, configure it with best JDK
    if [ -z "$JDK_HOME" ] || ! _is_valid_jdk "$JDK_HOME"; then
        if _is_valid_jdk "${JAVA_HOME:-}"; then
            export JDK_HOME="$JAVA_HOME"
        elif [ -n "$_best_jdk" ]; then
            export JDK_HOME="$_best_jdk"
            _add_to_path "$_best_jdk/bin"
        fi
    fi
}
_setup_java
unset -f _setup_java _is_valid_jre _is_valid_jdk _add_to_path