#!/bin/bash
set -euo pipefail

DEV=${DDR_DEV:-/sys/class/devfreq/dmc}
STATE_DIR=${DDR_STATE_DIR:-/tmp/orangepi-ddr-mode}

usage() {
    cat <<'EOF'
Usage:
  sudo ./scripts/ddr_mode.sh status
  sudo ./scripts/ddr_mode.sh performance
  sudo ./scripts/ddr_mode.sh ondemand
  sudo ./scripts/ddr_mode.sh restore
EOF
}

require_dev() {
    if [[ ! -d "$DEV" ]]; then
        echo "DDR devfreq node not found: $DEV" >&2
        exit 1
    fi
}

show_status() {
    require_dev
    echo "DDR devfreq node: $DEV"
    [[ -f "$DEV/name" ]] && echo "name: $(cat "$DEV/name")"
    [[ -f "$DEV/governor" ]] && echo "governor: $(cat "$DEV/governor")"
    [[ -f "$DEV/available_governors" ]] && echo "available_governors: $(cat "$DEV/available_governors")"
    [[ -f "$DEV/min_freq" ]] && echo "min_freq: $(cat "$DEV/min_freq")"
    [[ -f "$DEV/max_freq" ]] && echo "max_freq: $(cat "$DEV/max_freq")"
    [[ -f "$DEV/cur_freq" ]] && echo "cur_freq: $(cat "$DEV/cur_freq")"
    [[ -f "$DEV/available_frequencies" ]] && echo "available_frequencies: $(cat "$DEV/available_frequencies")"
}

save_state() {
    mkdir -p "$STATE_DIR"
    [[ -f "$DEV/governor" ]] && cat "$DEV/governor" > "$STATE_DIR/governor"
    [[ -f "$DEV/min_freq" ]] && cat "$DEV/min_freq" > "$STATE_DIR/min_freq"
    [[ -f "$DEV/max_freq" ]] && cat "$DEV/max_freq" > "$STATE_DIR/max_freq"
}

set_performance() {
    require_dev
    save_state
    if [[ -f "$DEV/available_governors" ]] && grep -qw performance "$DEV/available_governors"; then
        echo performance > "$DEV/governor"
    elif [[ -f "$DEV/available_frequencies" ]]; then
        max=$(tr ' ' '\n' < "$DEV/available_frequencies" | sort -n | tail -n1)
        echo "$max" > "$DEV/min_freq"
        echo "$max" > "$DEV/max_freq"
    else
        echo "No performance governor or available_frequencies for $DEV" >&2
        exit 1
    fi
    show_status
}

set_ondemand() {
    require_dev
    if [[ -f "$DEV/available_governors" ]] && grep -qw dmc_ondemand "$DEV/available_governors"; then
        echo dmc_ondemand > "$DEV/governor"
    else
        echo "dmc_ondemand governor not available for $DEV" >&2
        exit 1
    fi
    show_status
}

restore_state() {
    require_dev
    if [[ ! -d "$STATE_DIR" ]]; then
        echo "No saved DDR state found in $STATE_DIR" >&2
        exit 1
    fi
    [[ -f "$STATE_DIR/governor" ]] && cat "$STATE_DIR/governor" > "$DEV/governor"
    [[ -f "$STATE_DIR/min_freq" ]] && cat "$STATE_DIR/min_freq" > "$DEV/min_freq"
    [[ -f "$STATE_DIR/max_freq" ]] && cat "$STATE_DIR/max_freq" > "$DEV/max_freq"
    show_status
}

case "${1:-status}" in
    status)
        show_status
        ;;
    performance)
        set_performance
        ;;
    ondemand)
        set_ondemand
        ;;
    restore)
        restore_state
        ;;
    -h|--help|help)
        usage
        ;;
    *)
        usage
        exit 1
        ;;
esac