Add structured logging functionality to enhance debugging capabilities

lib/log.lua

@@ -0,0 +1,45 @@
+-- lib/log.lua — Structured logging for CC:Tweaked programs
+-- Usage:
+--   local log = dofile("lib/log.lua")
+--   log.info("SMELT", "Loaded %d recipes", count)
+--   log.warn("NET",   "No modem found")
+--   log.setLevel("DEBUG")   -- show everything
+--
+-- Levels: DEBUG < INFO < WARN < ERROR
+-- Default level: INFO (suppresses DEBUG)
+
+local LEVELS = { DEBUG = 1, INFO = 2, WARN = 3, ERROR = 4 }
+local minLevel = LEVELS.INFO
+
+local log = {}
+
+--- Set minimum log level (string: "DEBUG", "INFO", "WARN", "ERROR")
+function log.setLevel(level)
+    minLevel = LEVELS[level] or LEVELS.INFO
+end
+
+--- Get the current minimum level name
+function log.getLevel()
+    for name, val in pairs(LEVELS) do
+        if val == minLevel then return name end
+    end
+    return "INFO"
+end
+
+local function emit(levelName, tag, msg, ...)
+    if LEVELS[levelName] < minLevel then return end
+    local text
+    if select("#", ...) > 0 then
+        text = string.format(msg, ...)
+    else
+        text = msg
+    end
+    print(string.format("[%s][%s] %s", levelName, tag, text))
+end
+
+function log.debug(tag, msg, ...) emit("DEBUG", tag, msg, ...) end
+function log.info(tag, msg, ...)  emit("INFO",  tag, msg, ...) end
+function log.warn(tag, msg, ...)  emit("WARN",  tag, msg, ...) end
+function log.error(tag, msg, ...) emit("ERROR", tag, msg, ...) end
+
+return log