@logtape/windows-eventlog/dist/sink.deno.js

Windows Event Log sink for LogTape

import { DEFAULT_EVENT_ID_MAPPING } from "./types.js";
import { validateWindowsPlatform } from "./platform.js";
import { EVENTLOG_ERROR_TYPE, EVENTLOG_INFORMATION_TYPE, EVENTLOG_WARNING_TYPE, WindowsEventLogFFI } from "./ffi.deno.js";
import { getLogger } from "@logtape/logtape";

//#region sink.deno.ts
/**
* Formats a log record message into a string suitable for Windows Event Log.
* Combines the template and arguments into a readable message.
*/
function formatMessage(record) {
	let message = "";
	for (let i = 0; i < record.message.length; i++) if (i % 2 === 0) message += record.message[i];
	else {
		const arg = record.message[i];
		if (typeof arg === "string") message += arg;
		else message += JSON.stringify(arg);
	}
	return message;
}
/**
* Formats additional context information for the log entry.
* Includes category, properties, and other metadata.
*/
function formatContext(record) {
	const context = [];
	if (record.category && record.category.length > 0) context.push(`Category: ${record.category.join(".")}`);
	if (record.properties && Object.keys(record.properties).length > 0) context.push(`Properties: ${JSON.stringify(record.properties)}`);
	context.push(`Timestamp: ${new Date(record.timestamp).toISOString()}`);
	return context.length > 0 ? `\n\n${context.join("\n")}` : "";
}
/**
* Maps LogTape log levels to Windows Event Log types.
*/
function getEventType(level) {
	switch (level) {
		case "fatal":
		case "error": return EVENTLOG_ERROR_TYPE;
		case "warning": return EVENTLOG_WARNING_TYPE;
		case "info":
		case "debug":
		case "trace":
		default: return EVENTLOG_INFORMATION_TYPE;
	}
}
/**
* Creates a Windows Event Log sink for Deno environments using FFI.
*
* This implementation uses Deno's Foreign Function Interface to directly
* call Windows Event Log APIs, providing reliable Event Log integration
* without depending on external packages.
*
* @param options Configuration options for the sink
* @returns A LogTape sink that writes to Windows Event Log
* @throws {WindowsPlatformError} If not running on Windows
* @throws {WindowsEventLogError} If Event Log operations fail
*
* @example
* ```typescript
* import { getWindowsEventLogSink } from "@logtape/windows-eventlog";
*
* const sink = getWindowsEventLogSink({
*   sourceName: "MyApp"
* });
* ```
*
* @since 1.0.0
*/
function getWindowsEventLogSink(options) {
	validateWindowsPlatform();
	const { sourceName, eventIdMapping = {} } = options;
	const eventIds = {
		...DEFAULT_EVENT_ID_MAPPING,
		...eventIdMapping
	};
	let ffi = null;
	const metaLogger = getLogger([
		"logtape",
		"meta",
		"windows-eventlog"
	]);
	const sink = (record) => {
		if (!ffi) try {
			ffi = new WindowsEventLogFFI(sourceName);
			ffi.initialize();
		} catch (error) {
			metaLogger.error("Failed to initialize Windows Event Log FFI: {error}", { error });
			return;
		}
		const message = formatMessage(record);
		const context = formatContext(record);
		const fullMessage = message + context;
		const eventType = getEventType(record.level);
		const eventId = eventIds[record.level];
		try {
			ffi.writeEvent(eventType, eventId, fullMessage);
		} catch (error) {
			metaLogger.error("Failed to write {level} message to Windows Event Log: {error}", {
				level: record.level,
				error
			});
		}
	};
	sink[Symbol.dispose] = () => {
		if (ffi) {
			ffi.dispose();
			ffi = null;
		}
	};
	return sink;
}

//#endregion
export { getWindowsEventLogSink };
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