package com.grafana.demo;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
import io.opentelemetry.sdk.autoconfigure.AutoConfiguredOpenTelemetrySdk;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.boot.env.OriginTrackedMapPropertySource;
import org.springframework.context.event.EventListener;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.PropertySource;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

@SpringBootApplication
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

	private Pattern pattern = Pattern.compile(
            "^Config resource 'class path resource \\[(.+)]' via location 'optional:classpath:/'$"
	);

	@EventListener
	public void on(ApplicationReadyEvent event) throws IOException {
		// get the application.yaml file that was used to start the application
		ConfigurableEnvironment environment = event.getApplicationContext().getEnvironment();
		if (environment.getProperty("otel.file_format") == null) {
			System.out.println("otel.file_format is not set, skipping application.yaml extraction.");
			return;
		}

		for (PropertySource<?> propertySource : environment.getPropertySources()) {
			if (propertySource instanceof OriginTrackedMapPropertySource source) {
                String name = source.getName();
				System.out.println("Property Source: " + name);
				Matcher matcher = pattern.matcher(name);
				if (matcher.matches()) {
					String file = matcher.group(1);
					System.out.println("Found application.yaml: " + file);

                    try (InputStream resourceAsStream = event.getClass().getClassLoader().getResourceAsStream(file)) {
						// Print the contents of the application.yaml file
						if (resourceAsStream != null) {
							String content = new String(resourceAsStream.readAllBytes());
							System.out.println("Contents of " + file + ":");
							System.out.println(content);

							extractOtelConfigFile(content);
						} else {
							System.out.println("Could not find the application.yaml file in the classpath.");
						}
                    }
				}
			}
		}
	}

	private void extractOtelConfigFile(String content) throws IOException {
//		https://github.com/open-telemetry/opentelemetry-configuration/blob/c205770a956713e512eddb056570a99737e3383a/examples/kitchen-sink.yaml#L11

		// 1. read to yaml tree in jackson
		ObjectMapper yamlMapper = new ObjectMapper(new YAMLFactory());
		JsonNode rootNode = yamlMapper.readTree(content);

		// 2. find the "otel" node
		JsonNode otelNode = rootNode.get("otel");
		if (otelNode == null) {
			System.out.println("No 'otel' configuration found in the YAML file.");
			return;
		}

		// 3. write the "otel" node to a temp file
		File tempFile = File.createTempFile("otel-config", ".yaml");
		try (FileWriter writer = new FileWriter(tempFile)) {
			writer.write(yamlMapper.writeValueAsString(otelNode));
		}

		System.out.println("OpenTelemetry configuration extracted to: " + tempFile.getAbsolutePath());

		// Set the system property to point to the extracted config file
		String key = "otel.experimental.config.file";
		System.setProperty(key, tempFile.getAbsolutePath());
		System.out.println("Set system property " + key + "=" + tempFile.getAbsolutePath());

		AutoConfiguredOpenTelemetrySdk sdk = AutoConfiguredOpenTelemetrySdk.initialize();
		System.out.println("OpenTelemetry SDK initialized with configuration from: " + sdk.getOpenTelemetrySdk());

		// print the config file

		System.out.println("OpenTelemetry configuration file content:");
		try (InputStream inputStream = new FileInputStream(tempFile)) {
			String configContent = new String(inputStream.readAllBytes());
			System.out.println(configContent);
		} catch (IOException e) {
			System.err.println("Error reading the OpenTelemetry configuration file: " + e.getMessage());
		}

		tempFile.delete();
	}
}