parser.go

package main

import (
	"fmt"
	"maps"
	"slices"
	"sort"
	"strings"

	"github.com/fatih/color"
	"github.com/tidwall/gjson"
)

var (
	dimStyle  = color.New(color.Faint)
	boldStyle = color.New(color.Bold)
)

func processLine(line string, cfg *config, formatTime func(string) string) string {
	trimmed := strings.TrimSpace(line)
	if len(trimmed) == 0 || trimmed[0] != '{' {
		return line
	}

	parsed := gjson.Parse(trimmed)
	if parsed.Type != gjson.JSON {
		return line
	}

	keys := make(map[string]string)
	flatten(parsed, "", keys, cfg.exclude)

	var b strings.Builder
	if ts, ok := keys[cfg.tsField]; ok {
		delete(keys, cfg.tsField)

		b.WriteString(dimStyle.Sprint(formatTime(ts)))
		b.WriteByte(' ')
	}

	if lvl, ok := keys[cfg.levelField]; ok {
		delete(keys, cfg.levelField)

		b.WriteString(formatLevel(lvl))
		b.WriteByte(' ')
	}

	if msg, ok := keys[cfg.msgField]; ok {
		delete(keys, cfg.msgField)

		b.WriteString(boldStyle.Sprint(msg))
	}

	keySlice := slices.Collect(maps.Keys(keys))
	sort.Strings(keySlice)

	for _, key := range keySlice {
		val := keys[key]
		_, _ = fmt.Fprintf(&b, " %s=%s", coloredKey(key), val)
	}

	return b.String()
}

func flatten(result gjson.Result, prefix string, out map[string]string, exclude map[string]struct{}) {
	switch {
	case result.IsObject():
		result.ForEach(func(key, value gjson.Result) bool {
			newKey := key.String()
			if prefix != "" {
				newKey = prefix + "." + newKey
			}
			if _, ok := exclude[newKey]; ok {
				return true
			}

			flatten(value, newKey, out, exclude)

			return true
		})

	case result.IsArray():
		out[prefix] = result.Raw

	default:
		out[prefix] = result.String()
	}
}