#!/usr/bin/env bash
# powerdown-functions

shopt -s nullglob extglob

# turn on kernel options
opt() {
    [[ -f "$1" ]] || return
    [[ -w "$1" ]] && echo "$2" | tee "$1" &>/dev/null || echo "[powerdown] cannot write $2 to $1"
}

# unload kernel module
unload_mod() {
    has_mod "$1" || return
    modprobe -r "$1" || echo "[powerdown] cannot unload module $1"
}

unload_mod_recursive() {
	local dep
	for dep in $(lsmod | awk -v mod="$1" '$1==mod {gsub(",", " ", $4); print $4}'); do
		unload_mod_recursive "$dep"
	done
	unload_mod "$1"
}

# load kernel module
load_mod() {
    has_mod "$1" || return
    modprobe "$1" || echo "[powerdown] cannot load module $1"
}

# module exists
has_mod() {
    modprobe -nq "$1"
}

# module loaded
mod_loaded() {
    grep -qs "^$1 " /proc/modules
}

# brightness scale 0 to 5
# $1 = max file
# $2 = value
num_scale() {
    echo $(($(< "$1") / 5 * $2))
}

# command
run() {
    "$@" &> /dev/null || echo "[powerdown] cannot run $@"
}

has_bat() {
	local bat
	for bat in /sys/class/power_supply/BAT*; do
		return 0
	done
	return 1
}

# get current power usage
display_power() {
    if ! has_bat; then
        echo "[powerdown] no battery"
        return
    fi
    local bat
    for bat in /sys/class/power_supply/BAT*; do
        local watt
        if [[ -f "$bat/power_now" ]]; then
            watt="$(bc <<< "scale=3; $(< "$bat/power_now") / 1000000")"
        else
            watt="$(bc <<< "scale=3; $(< "$bat/current_now") * $(< "$bat/voltage_now") / 1000000000000")"
        fi
        echo "[powerdown] $(basename "$bat") using $watt watts"
    done
}

# get readahead
display_readahead() {
    echo "- $1 readahead: $(blockdev --getra "$1")"
}

# dump kernel option content
dump () {
    [[ -r "$1" ]] || return
    echo "- $1: $(< "$1")"
}

display_module() {
    has_mod "$1" || return
    echo -n "- $1 "
    mod_loaded "$1" && echo "loaded" || echo "not loaded"
}

display_wireless() {
    echo "- $1 $(iw dev "$1" get power_save)"
}

hibernate_offset() {
    filefrag -v /hibernate | awk 'NR==4 {print $4}' | tr -d .
}

root_part() {
    df / | awk 'NR==2 {print $1}'
}

has_swap_part () {
    grep -qs swap /etc/fstab
}

can_suspend_to_disk () {
    [[ -f /hibernate ]] || has_swap_part
}

swap_part() {
    awk '$3=="swap" {print $1; exit}' /etc/fstab
}

resume_boot_option() {
    if [[ -f /hibernate ]]; then
        echo "resume=$(root_part) resume_offset=$(hibernate_offset)"
    elif has_swap_part; then
        echo "resume=$(swap_part)"
    fi
}

# lock the file until the script finishes
lock() {
    local LOCK=/tmp/powerdown.lock
    if ! mkdir "$LOCK" 2> /dev/null; then
        echo "Working... $LOCK"
        exit
    fi
    trap "rm -rf $LOCK" EXIT
}

# $1 = device path
is_usb_hid() {
    local subdev
    for subdev in $1/*:*; do
        # USB_DEVICE_CLASS 3 = HID
        [[ "$(< "$subdev/bInterfaceClass")" == 03 ]] && return 0
    done
    return 1
}

usb_powersave() {
    local usbdev
    for usbdev in /sys/bus/usb/devices/+([^:]); do
        is_usb_hid "$usbdev" && opt "$usbdev/power/control" on || opt "$usbdev/power/control" auto
    done
}