Write log messages from the daemon to a file

src/debug.ts

@@ -1,29 +1,59 @@
 import { format } from 'util'
+import { createWriteStream } from 'node:fs'
+import { mkdirSync } from 'fs'
+
+type LogWriter = (logEntry: string) => void
+let isClient = true
+let logWriter: LogWriter = console.error
+
+const useColor = () => process.stderr.isTTY && isClient
 
 const yellow = (s: string) =>
-  process.stderr.isTTY ? `\x1b[43;30m${s}\x1b[m` : s
-const blue = (s: string) =>
-  process.stderr.isTTY ? `\x1b[44;37m${s}\x1b[m` : s
+  useColor() ? `\x1b[43;30m${s}\x1b[m` : s
+const blue = (s: string) => (useColor() ? `\x1b[44;37m${s}\x1b[m` : s)
 const red = (s: string) =>
-  process.stderr.isTTY ? `\x1b[41;30;1m${s}\x1b[m` : s
+  useColor() ? `\x1b[41;30;1m${s}\x1b[m` : s
 const magenta = (s: string) =>
-  process.stderr.isTTY ? `\x1b[45;30m${s}\x1b[m` : s
+  useColor() ? `\x1b[45;30m${s}\x1b[m` : s
 const green = (s: string) =>
-  process.stderr.isTTY ? `\x1b[42;30;2m${s}\x1b[m` : s
+  useColor() ? `\x1b[42;30;2m${s}\x1b[m` : s
 
 const level = parseInt(process.env.TSIMP_DEBUG || '0', 10)
 
+type Logger = (...args: any[]) => undefined
+
 const getLogger =
-  (name: string, color: (s: string) => string) =>
+  (name: string, color: (s: string) => string): Logger =>
   (...args: any[]) => {
     const prefix = `TSIMP ${color(name)} ${process.pid}: `
     const msg = format(...args).trim()
-    console.error(prefix + msg.split('\n').join(`\n${prefix}`))
+    logWriter(prefix + msg.split('\n').join(`\n${prefix}`))
+  }
+
+export let error: Logger
+export let warn: Logger
+export let debug: Logger
+export let info: Logger
+export let trace: Logger
+
+const initializeLoggers = () => {
+  error = getLogger('error', red)
+  warn = level > 0 ? getLogger('warn', yellow) : () => {}
+  debug = level > 1 ? getLogger('debug', magenta) : () => {}
+  info = level > 2 ? getLogger('info', blue) : () => {}
+  trace = getLogger('trace', green)
+}
+
+export const markProcessAsDaemon = () => {
+  if (isClient) {
+    isClient = false
+    mkdirSync('.tsimp/daemon', { recursive: true })
+    const writeStream = createWriteStream('.tsimp/daemon/log', {
+      flags: 'a',
+    })
+    logWriter = text => writeStream.write(`${text}\n`)
+    initializeLoggers()
   }
+}
 
-export const error = getLogger('error', red)
-export const warn = level > 0 ? getLogger('warn', yellow) : () => {}
-export const debug =
-  level > 1 ? getLogger('debug', magenta) : () => {}
-export const info = level > 2 ? getLogger('info', blue) : () => {}
-export const trace = getLogger('trace', green)
+initializeLoggers()

src/service/daemon.mts

@@ -1,4 +1,6 @@
 import { DaemonServer } from './service.js'
+import { markProcessAsDaemon } from '../debug.js'
+markProcessAsDaemon()
 const cwd = process.cwd()
 /* c8 ignore start */
 const home = (process.env.HOME ?? '').replace(/[\\\/]$/, '')