1
type LogLevel = "info" | "warn" | "error";
2
type LogContext = Record<string, unknown>;
3
 
4
function normalizeContext(context?: LogContext): LogContext | undefined {
5
  if (!context) {
6
    return undefined;
7
  }
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9
  return Object.fromEntries(Object.entries(context).filter(([, value]) => value !== undefined));
10
}
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12
function write(level: LogLevel, scope: string, event: string, message: string, context?: LogContext) {
13
  const entry = {
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    timestamp: new Date().toISOString(),
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    level,
16
    scope,
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    event,
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    message,
19
    ...normalizeContext(context),
20
  };
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22
  const payload = JSON.stringify(entry);
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24
  if (level === "error") {
25
    console.error(payload);
26
    return;
27
  }
28
 
29
  if (level === "warn") {
30
    console.warn(payload);
31
    return;
32
  }
33
 
34
  console.log(payload);
35
}
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37
export function errorContext(error: unknown) {
38
  if (error instanceof Error) {
39
    return {
40
      errorName: error.name,
41
      errorMessage: error.message,
42
    };
43
  }
44
 
45
  return {
46
    errorMessage: String(error),
47
  };
48
}
49
 
50
export function createLogger(scope: string) {
51
  return {
52
    info(event: string, message: string, context?: LogContext) {
53
      write("info", scope, event, message, context);
54
    },
55
    warn(event: string, message: string, context?: LogContext) {
56
      write("warn", scope, event, message, context);
57
    },
58
    error(event: string, message: string, context?: LogContext) {
59
      write("error", scope, event, message, context);
60
    },
61
  };
62
}