#!/usr/bin/env bash
#
# Displays per-core CPU usage as Unicode block characters.
# Uses a temp file to track deltas between intervals.
#
# ▄ = load below 50%
# █ = load at or above 50%
# Colors escalate through warn1 -> warn2 -> crit thresholds.

PREV_FILE="/tmp/i3blocks_cpu_prev"

. ~/bin/i3blocks/_utils
# Read current idle and total ticks for each core from /proc/stat
declare -a cur_idle cur_total
i=0
while IFS=' ' read -r cpu user nice system idle iowait irq softirq rest; do
    [[ "$cpu" =~ ^cpu[0-9]+$ ]] || continue
    cur_idle[$i]=$((idle + iowait))
    cur_total[$i]=$((user + nice + system + idle + iowait + irq + softirq))
    ((i++))
done < /proc/stat
num_cores=$i

# Load previous snapshot if available
declare -a prev_idle prev_total
if [[ -f "$PREV_FILE" ]]; then
    i=0
    while IFS=' ' read -r p_idle p_total; do
        prev_idle[$i]=$p_idle
        prev_total[$i]=$p_total
        ((i++))
    done < "$PREV_FILE"
fi

# Save current snapshot for next run
for ((i=0; i<num_cores; i++)); do
    echo "${cur_idle[$i]} ${cur_total[$i]}"
done > "$PREV_FILE"

# Build output — one block character per core
output=""
for ((i=0; i<num_cores; i++)); do
    delta_total=$(( cur_total[i] - ${prev_total[$i]:-0} ))
    delta_idle=$(( cur_idle[i] - ${prev_idle[$i]:-0} ))

    if [[ $delta_total -eq 0 ]]; then
        pct=0
    else
        pct=$(( (delta_total - delta_idle) * 100 / delta_total ))
    fi

    color=""
    if [[ $pct -ge 50 ]]; then
        color=$crit_bg
        char="█"
    elif [[ $pct -ge 15 ]]; then
        color=$warn1_bg
        char="▄"
    else
        char="_"
    fi

    if [[ -n "$color" ]]; then
        output+="<span color=\"${color}\">${char}</span>"
    else
        output+="${char}"
    fi
done

echo -e "CPU $output\n"