# Setup Rust / Cargo environment, tools, and shell completions
_setup_cargo() {
    [ -n "$ZSH_VERSION" ] && setopt localoptions nonomatch nullglob

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

    # 1. Respect or detect CARGO_HOME and RUSTUP_HOME
    if [ -z "$CARGO_HOME" ] && [ -d "$HOME/.cargo" ]; then
        export CARGO_HOME="$HOME/.cargo"
    fi
    if [ -z "$RUSTUP_HOME" ] && [ -d "$HOME/.rustup" ]; then
        export RUSTUP_HOME="$HOME/.rustup"
    fi

    _cargo_dir="${CARGO_HOME:-$HOME/.cargo}"

    # 2. Source official env file if present, or add bin directory to PATH
    if [ -f "$_cargo_dir/env" ]; then
        \. "$_cargo_dir/env"
    elif [ -d "$_cargo_dir/bin" ]; then
        _add_to_path "$_cargo_dir/bin"
    fi

    # 3. Fallback search for system or alternative Cargo/Rust locations if not in PATH
    if ! command -v cargo >/dev/null 2>&1; then
        for _cand in \
            "/usr/local/cargo/bin" \
            "/opt/homebrew/opt/rust/bin" \
            "/usr/local/opt/rust/bin" \
            "/opt/homebrew/bin" \
            "/usr/local/bin" \
            "$HOME/.local/bin"
        do
            if [ -x "$_cand/cargo" ]; then
                _add_to_path "$_cand"
                break
            fi
        done
    fi

    # 4. Enable shell completions if available and files are present
    if command -v cargo >/dev/null 2>&1; then
        _rustup_dir="${RUSTUP_HOME:-$HOME/.rustup}"

        if [ -n "$BASH_VERSION" ]; then
            for _comp in \
                "$_rustup_dir"/toolchains/*/etc/bash_completion.d/cargo \
                "$_rustup_dir"/toolchains/*/etc/bash_completion.d/rustup \
                "/opt/homebrew/etc/bash_completion.d/cargo" \
                "/usr/share/bash-completion/completions/cargo"
            do
                if [ -r "$_comp" ]; then
                    \. "$_comp"
                fi
            done
        elif [ -n "$ZSH_VERSION" ]; then
            for _zsh_comp_dir in "$_rustup_dir"/toolchains/*/share/zsh/site-functions; do
                if [ -d "$_zsh_comp_dir" ]; then
                    case " ${fpath[*]} " in
                        *" $_zsh_comp_dir "*) ;;
                        *) fpath=("$_zsh_comp_dir" "${fpath[@]}") ;;
                    esac
                fi
            done
        fi
    fi
}
_setup_cargo
unset -f _setup_cargo _add_to_path