TCL: Make code cleaner from nested if-statements

This is a procedure of one of the items of the status bar on i3 window manager on linux. Is run every second. Basically deals with frequency governors. If temperature reaches a certain number then switch to powersave mode, or if a certain application is running, e.g. steam, or the laptop is running on batteries. If temperature reaches a lower point then it will switch to performance, etc.

The procedure runs very well so far, no issues. However the code aesthetically does not look good to me, because it has some many nested if-else statements, that when I add something new it is hard to follow, maintain and understand.

proc cpu_freq {} {
    set app steam
    set cpu_power [exec sudo cpupower frequency-info | sed -ne /speed/p]
    set cpu_temp [exec sensors | grep Core | sed -n  {2p} | awk {{print $3}} | cut -c2-3]
    set battery [exec acpi]
    if {[string match *performance* $cpu_power]} {set cpu_freq HIGH; set color "$::green"}
    if {[string match *powersave* $cpu_power]}   {set cpu_freq LOW;  set color "$::red"}
    if {![file isfile $::i3dir/powersave.freq] && ![file isfile $::i3dir/performance.freq]} {
        set switch AUTO
    }
        # ON BATTERY 
    if {[string match *Discharging* $battery]} {
        # WHEN IN PERFORMANCE MODE
        if {[string match *performance* $cpu_power]} {
           if {![file isfile $::i3dir/performance.freq]} {
               # AND NOT IN MANUAL
               # SWITCH TO POWERSAVE 
               exec sudo cpupower frequency-set -g powersave
               set cpu_freq LOW
               set switch AUTO
               set color "$::red"
               set ::on_battery true
          } else { 
              # SWITCH TO MANUAL PERFORMANCE MODE
              if {[file isfile $::i3dir/performance.freq]} {
                  exec sudo cpupower frequency-set -g performance
                  set cpu_freq HIGH
                  set switch MAN
                  set color "$::green"
                  set ::on_battery true
              } else {
             if {[file isfile $::i3dir/powersave.freq]} {
                 # SWITCH TO MANUAL POWERSAVE MODE 
                 exec sudo cpupower frequency-set -g powersave
                 set cpu_freq LOW
                 set switch MAN
                 set color "$::red"
                 set ::on_battery true
              }
              }                
           } 
       } else {
       # WHEN IN POWERSAVE MODE (AUTO)
       # SWITCH TO MANUAL POWERSAVE
       if {[string match *powersave* $cpu_power]} {
          if {[file isfile $::i3dir/powersave.freq]} {
              exec sudo cpupower frequency-set -g powersave
              set cpu_freq LOW
              set switch MAN
              set color "$::red"
              set ::on_battery true
          } else {
       # SWITCH TO MANUAL PERFORMANCE
          if {[file isfile $::i3dir/performance.freq]} {
              exec sudo cpupower frequency-set -g performance
              set cpu_freq HIGH
              set switch MAN
              set color "$::green"
              set ::on_battery true
             }
          }
       }
    }
       # ON MAINS
    } else {
         # WHEN IN POWERSAVE MODE
         if {[string match *powersave* $cpu_power]} {
                # RUNNING APP OR MANUAL SWITCH
            if {[file isfile $::i3dir/powersave.freq]} {
                set cpu_freq LOW
                set switch MAN
                } else {
            if {[isRunning $app]} {
                set cpu_freq LOW
                set switch AUTO
                # DO NOTHING, KEEP RUNNING IN POWERSAVE MODE
                } else {
                # SWITCH TO PERFORMANCE AFTER RUNNING ON BATTERIES
                if {$::on_battery==true} {
                    exec sudo cpupower frequency-set -g performance
                    set cpu_freq HIGH
                    set switch AUTO
                    set color "$::green"
                    set ::on_battery false
                # SWITCH TO PERFORMANCE WHEN REACHING LOWER TEMPS
                } elseif {$cpu_temp <= 55} {
                    exec sudo cpupower frequency-set -g performance
                    set cpu_freq HIGH
                    set switch AUTO
                    set color "$::green"
                   }
                }
            }
         # WHEN IN PERFORMANCE MODE
        } else {
                # MANUAL SWITCH
            if {[file isfile $::i3dir/performance.freq]} {
                set switch MAN
                set cpu_freq HIGH
                # DO NOTHING, KEEP RUNNING IN PERFORMANCE MODE
                } else {
                # HOT TEMPERATURE OR RUNNING APP
                # SWITCH TO POWERSAVE
                if {$cpu_temp >= 75 || [isRunning $app] } {
                    exec sudo cpupower frequency-set -g powersave
                    set cpu_freq LOW
                    set switch AUTO
                    set color "$::red"
                } else {
                    set cpu_freq HIGH
                    set switch AUTO
                }
            }
        } 
    }
    set stdout {{"name":"cpu_freq","full_text":"$switch:$cpu_freq","color":"$color"}}
    set stdout [subst -nocommands $stdout]
    puts -nonewline $stdout
}