From 34add1a7290bd16fbb6aee4086b6c56fad7c9287 Mon Sep 17 00:00:00 2001
From: Jonathan Bernard <jonathan@jdbernard.com>
Date: Sat, 4 Jan 2025 23:01:17 -0600
Subject: [PATCH] Add the ability to filter by log level and namespace.

---
 slfmt.nimble  |  4 +--
 src/slfmt.nim | 89 ++++++++++++++++++++++++++++++++++++---------------
 2 files changed, 65 insertions(+), 28 deletions(-)

diff --git a/slfmt.nimble b/slfmt.nimble
index eca3386..11dc860 100644
--- a/slfmt.nimble
+++ b/slfmt.nimble
@@ -1,6 +1,6 @@
 # Package
 
-version       = "0.1.1"
+version       = "0.1.2"
 author        = "Jonathan Bernard"
 description   = "Small utility to pretty-print strucutured logs."
 license       = "MIT"
@@ -10,5 +10,5 @@ bin           = @["slfmt"]
 
 # Dependencies
 
-requires "nim >= 2.2.0"
+requires @["nim >= 2.2.0", "docopt"]
 requires "timeutils"
diff --git a/src/slfmt.nim b/src/slfmt.nim
index 3c111f9..1a3abca 100644
--- a/src/slfmt.nim
+++ b/src/slfmt.nim
@@ -1,19 +1,34 @@
-import std/[json, sequtils, streams, strutils, terminal, times]
+import std/[json, options, sequtils, streams, strutils, terminal, times]
 import timeutils
-#import docopt
+import docopt
 
-const VERSION = "0.1.0"
+from std/logging import Level
 
-# const USAGE = """Usage:
-#   slfmt
-#
-# Options:
-#
-#   -h, --help            Print this usage and help information
+const VERSION = "0.1.2"
+
+const USAGE = """Usage:
+   slfmt [options]
+
+Options:
+
+   -h, --help               Print this usage and help information
+   -l, --log-level <lvl>    Only show log events at or above this level
+   -n, --namespace <ns>     Only show log events from this namespace
+"""
 
 const fieldDisplayOrder = @[
   "scope", "level", "ts", "code", "sid", "sub", "msg", "err", "stack", "method", "args"]
 
+func parseLogLevel(s: string): Level =
+  case s.toUpper
+  of "DEBUG": result = Level.lvlDebug
+  of "INFO": result = Level.lvlInfo
+  of "NOTICE": result = Level.lvlNotice
+  of "WARN": result = Level.lvlWarn
+  of "ERROR": result = Level.lvlError
+  of "FATAL": result = Level.lvlFatal
+  else: result = Level.lvlAll
+
 func decorate(
     s: string,
     fg = fgDefault,
@@ -42,38 +57,60 @@ proc formatField(name: string, value: JsonNode): string =
     of "err": strVal = decorate(value.getStr, fgRed)
     of "msg": strVal = decorate(value.getStr, fgYellow)
     of "stack": strVal = decorate(value.getStr, fgBlack, {styleBright})
-    else: strVal = pretty(value)
+    else:
+      if value.kind == JString: strVal = decorate(value.getStr)
+      else: strVal = pretty(value)
 
   let valLines = splitLines(strVal)
   if name.len > 10 or strVal.len + 16 > terminalWidth() or valLines.len > 1:
     result &= "\n" & valLines.mapIt("  " & it).join("\n") & "\n"
   else: result &= strVal & "\n"
 
-proc prettyPrintFormat(logLine: string): string =
-  try:
-    var logJson = parseJson(logLine)
+proc prettyPrintFormat(logJson: JsonNode): string =
+  result = '-'.repeat(terminalWidth()) & "\n"
 
-    result = '-'.repeat(terminalWidth()) & "\n"
+  # Print the known fields in order first
+  for f in fieldDisplayOrder:
+    if logJson.hasKey(f):
+      result &= formatField(f, logJson[f])
+      logJson.delete(f)
 
-    # Print the known fields in order first
-    for f in fieldDisplayOrder:
-      if logJson.hasKey(f):
-        result &= formatField(f, logJson[f])
-        logJson.delete(f)
+  # Print the rest of the fields
+  for (key, val) in pairs(logJson): result &= formatField(key, val)
 
-    # Print the rest of the fields
-    for (key, val) in pairs(logJson): result &= formatField(key, val)
+  result &= "\n"
 
-    result &= "\n"
-
-  except ValueError, JsonParsingError:
-    result = logLine
+proc parseLogLine(logLine: string): JsonNode =
+  result = parseJson(logLine)
 
 when isMainModule:
   try:
+    let args = docopt(USAGE, version = VERSION)
+
+    let logLevel =
+      if args["--log-level"]: some(parseLogLevel($args["--log-level"]))
+      else: none[Level]()
+
+    let namespace =
+      if args["--namespace"]: some($args["--namespace"])
+      else: none[string]()
+
     var line: string = ""
     let sin = newFileStream(stdin)
-    while(sin.readLine(line)): stdout.writeLine(prettyPrintFormat(line))
+    while(sin.readLine(line)):
+      try:
+        let logJson = parseLogLine(line)
+
+        if logLevel.isSome and logJson.hasKey("level"):
+          let lvl = parseLogLevel(logJson["level"].getStr)
+          if lvl < logLevel.get: continue
+
+        if namespace.isSome and logJson.hasKey("scope"):
+          if not logJson["scope"].getStr.startsWith(namespace.get): continue
+
+        stdout.writeLine(prettyPrintFormat(logJson))
+      except ValueError, JsonParsingError:
+        stdout.writeLine(line)
   except:
     stderr.writeLine("slfmt - FATAL: " & getCurrentExceptionMsg())
     stderr.writeLine(getCurrentException().getStackTrace())