feat(log): set style per level

[reitzig]

Fixes #944

Changes

• add new options, one per log level
• use them

Demonstration

Test Script

#!/usr/bin/env bash

mkdir -p out
go build -o out -v ./...

log_all_levels() {
  echo "---"
  out/gum log --level=none  "Nothing"
  out/gum log --level=debug "A Detail"
  out/gum log --level=info  "A Note"
  out/gum log --level=warn  "A Warning"
  out/gum log --level=error "An Error"
  out/gum log --level=fatal "A Fuckup"
  echo "---"
}

echo "Defaults:"
log_all_levels || true
echo ""

echo "Legacy:"
export GUM_LOG_LEVEL_FOREGROUND="#ea76cb"
env | grep GUM_LOG_LEVEL_
log_all_levels || true
echo ""

echo "Some customization, fallback to legacy:"
echo "Style per level:"
export GUM_LOG_LEVEL_DEBUG_FOREGROUND="#6c6f85"
export GUM_LOG_LEVEL_INFO_FOREGROUND="#6c6f85"
env | grep GUM_LOG_LEVEL_
log_all_levels || true
echo ""

echo "Style per level:"
export GUM_LOG_LEVEL_DEBUG_FOREGROUND="#6c6f85"
export GUM_LOG_LEVEL_INFO_FOREGROUND="#04a5e5"
export GUM_LOG_LEVEL_WARN_FOREGROUND="#df8e1d"
export GUM_LOG_LEVEL_ERROR_FOREGROUND="#dd7878"
export GUM_LOG_LEVEL_FATAL_FOREGROUND="#d20f39"
env | grep GUM_LOG_LEVEL_
log_all_levels || true

[reitzig]

If there's a neater way to check "has the user set any level.$level. option?", I'm all ears :)

Or a style merge, for that matter. 💁‍♂️

[reitzig]

Not sure why GitHub proposed @tauraamui and @kujtimiihoxha as reviewers; @caarlos0 , how to best proceed here?