add in-built logging support for a better dev experience

vendor/github.com/aybabtme/humanlog/logfmt_handler.go

@@ -0,0 +1,239 @@
+package humanlog
+
+import (
+	"bytes"
+	"fmt"
+	"sort"
+	"strconv"
+	"strings"
+	"text/tabwriter"
+	"time"
+
+	"github.com/fatih/color"
+	"github.com/go-logfmt/logfmt"
+)
+
+// LogfmtHandler can handle logs emmited by logrus.TextFormatter loggers.
+type LogfmtHandler struct {
+	buf     *bytes.Buffer
+	out     *tabwriter.Writer
+	truncKV int
+
+	Opts *HandlerOptions
+
+	Level   string
+	Time    time.Time
+	Message string
+	Fields  map[string]string
+
+	last map[string]string
+}
+
+func (h *LogfmtHandler) clear() {
+	h.Level = ""
+	h.Time = time.Time{}
+	h.Message = ""
+	h.last = h.Fields
+	h.Fields = make(map[string]string)
+	if h.buf != nil {
+		h.buf.Reset()
+	}
+}
+
+// CanHandle tells if this line can be handled by this handler.
+func (h *LogfmtHandler) TryHandle(d []byte) bool {
+	if !bytes.ContainsRune(d, '=') {
+		return false
+	}
+
+	if !h.UnmarshalLogfmt(d) {
+		h.clear()
+		return false
+	}
+	return true
+}
+
+// HandleLogfmt sets the fields of the handler.
+func (h *LogfmtHandler) UnmarshalLogfmt(data []byte) bool {
+	dec := logfmt.NewDecoder(bytes.NewReader(data))
+	for dec.ScanRecord() {
+	next_kv:
+		for dec.ScanKeyval() {
+			key := dec.Key()
+			val := dec.Value()
+			if h.Time.IsZero() {
+				foundTime := checkEachUntilFound(supportedTimeFields, func(field string) bool {
+					time, ok := tryParseTime(string(val))
+					if ok {
+						h.Time = time
+					}
+					return ok
+				})
+				if foundTime {
+					continue next_kv
+				}
+			}
+
+			if len(h.Message) == 0 {
+				foundMessage := checkEachUntilFound(supportedMessageFields, func(field string) bool {
+					if !bytes.Equal(key, []byte(field)) {
+						return false
+					}
+					h.Message = string(val)
+					return true
+				})
+				if foundMessage {
+					continue next_kv
+				}
+			}
+
+			if len(h.Level) == 0 {
+				foundLevel := checkEachUntilFound(supportedLevelFields, func(field string) bool {
+					if !bytes.Equal(key, []byte(field)) {
+						return false
+					}
+					h.Level = string(val)
+					return true
+				})
+				if foundLevel {
+					continue next_kv
+				}
+			}
+
+			h.setField(key, val)
+		}
+	}
+	return dec.Err() == nil
+}
+
+// Prettify the output in a logrus like fashion.
+func (h *LogfmtHandler) Prettify(skipUnchanged bool) []byte {
+	defer h.clear()
+	if h.out == nil {
+		if h.Opts == nil {
+			h.Opts = DefaultOptions
+		}
+		h.buf = bytes.NewBuffer(nil)
+		h.out = tabwriter.NewWriter(h.buf, 0, 1, 0, '\t', 0)
+	}
+
+	var (
+		msgColor       *color.Color
+		msgAbsentColor *color.Color
+	)
+	if h.Opts.LightBg {
+		msgColor = h.Opts.MsgLightBgColor
+		msgAbsentColor = h.Opts.MsgAbsentLightBgColor
+	} else {
+		msgColor = h.Opts.MsgDarkBgColor
+		msgAbsentColor = h.Opts.MsgAbsentDarkBgColor
+	}
+
+	var msg string
+	if h.Message == "" {
+		msg = msgAbsentColor.Sprint("<no msg>")
+	} else {
+		msg = msgColor.Sprint(h.Message)
+	}
+
+	lvl := strings.ToUpper(h.Level)[:imin(4, len(h.Level))]
+	var level string
+	switch h.Level {
+	case "debug":
+		level = h.Opts.DebugLevelColor.Sprint(lvl)
+	case "info":
+		level = h.Opts.InfoLevelColor.Sprint(lvl)
+	case "warn", "warning":
+		level = h.Opts.WarnLevelColor.Sprint(lvl)
+	case "error":
+		level = h.Opts.ErrorLevelColor.Sprint(lvl)
+	case "fatal", "panic":
+		level = h.Opts.FatalLevelColor.Sprint(lvl)
+	default:
+		level = h.Opts.UnknownLevelColor.Sprint(lvl)
+	}
+
+	var timeColor *color.Color
+	if h.Opts.LightBg {
+		timeColor = h.Opts.TimeLightBgColor
+	} else {
+		timeColor = h.Opts.TimeDarkBgColor
+	}
+	_, _ = fmt.Fprintf(h.out, "%s |%s| %s\t %s",
+		timeColor.Sprint(h.Time.Format(h.Opts.TimeFormat)),
+		level,
+		msg,
+		strings.Join(h.joinKVs(skipUnchanged, "="), "\t "),
+	)
+
+	_ = h.out.Flush()
+
+	return h.buf.Bytes()
+}
+
+func (h *LogfmtHandler) setLevel(val []byte)   { h.Level = string(val) }
+func (h *LogfmtHandler) setMessage(val []byte) { h.Message = string(val) }
+func (h *LogfmtHandler) setTime(val []byte) (parsed bool) {
+	valStr := string(val)
+	if valFloat, err := strconv.ParseFloat(valStr, 64); err == nil {
+		h.Time, parsed = tryParseTime(valFloat)
+	} else {
+		h.Time, parsed = tryParseTime(string(val))
+	}
+	return
+}
+
+func (h *LogfmtHandler) setField(key, val []byte) {
+	if h.Fields == nil {
+		h.Fields = make(map[string]string)
+	}
+	h.Fields[string(key)] = string(val)
+}
+
+func (h *LogfmtHandler) joinKVs(skipUnchanged bool, sep string) []string {
+
+	kv := make([]string, 0, len(h.Fields))
+	for k, v := range h.Fields {
+		if !h.Opts.shouldShowKey(k) {
+			continue
+		}
+
+		if skipUnchanged {
+			if lastV, ok := h.last[k]; ok && lastV == v && !h.Opts.shouldShowUnchanged(k) {
+				continue
+			}
+		}
+
+		kstr := h.Opts.KeyColor.Sprint(k)
+
+		var vstr string
+		if h.Opts.Truncates && len(v) > h.Opts.TruncateLength {
+			vstr = v[:h.Opts.TruncateLength] + "..."
+		} else {
+			vstr = v
+		}
+		vstr = h.Opts.ValColor.Sprint(vstr)
+		kv = append(kv, kstr+sep+vstr)
+	}
+
+	sort.Strings(kv)
+
+	if h.Opts.SortLongest {
+		sort.Stable(byLongest(kv))
+	}
+
+	return kv
+}
+
+type byLongest []string
+
+func (s byLongest) Len() int           { return len(s) }
+func (s byLongest) Less(i, j int) bool { return len(s[i]) < len(s[j]) }
+func (s byLongest) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+
+func imin(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}