package com.ankurm.ssews;

import java.util.List;

import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.web.server.LocalServerPort;

import static org.assertj.core.api.Assertions.assertThat;

/**
 * {@code .data(object)} and {@code .data(object, APPLICATION_JSON)} are not the same call.
 * This test prints both results side by side.
 */
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
        properties = "dashboard.broadcast.enabled=false")
class SseDataConversionTest {

    @LocalServerPort
    int port;

    @Test
    void mediaTypeDecidesTheConverter() throws Exception {
        List<String> lines;
        try (SseClient client = new SseClient(port, "/sse/payload")) {
            lines = client.readToEnd();
        }

        String withJson = dataAfter(lines, "event:with-json");
        String noMediaType = dataAfter(lines, "event:no-media-type");

        System.out.println("=== SseEmitter.event().data(record, APPLICATION_JSON) ===");
        System.out.println(withJson);
        System.out.println("=== SseEmitter.event().data(record)  [no media type] ===");
        System.out.println(noMediaType);

        assertThat(withJson).startsWith("{").contains("\"seq\":7").contains("\"host\":\"node-a\"");

        // The finding: for a POJO they are IDENTICAL. No media type does not mean toString().
        // send() asks the configured HttpMessageConverters which one canWrite(type, null), and
        // for a record the first (and only) answer is the Jackson converter.
        System.out.println("=== POJO: identical? " + withJson.equals(noMediaType) + " ===");
        assertThat(noMediaType).isEqualTo(withJson);

        String stringPlain = dataAfter(lines, "event:string-plain");
        String stringJson = dataAfter(lines, "event:string-json");
        System.out.println("=== String payload, no media type   -> " + stringPlain);
        System.out.println("=== String payload, APPLICATION_JSON -> " + stringJson);

        // The finding, and it is the opposite of what I expected when writing this test: for a
        // String the media type argument changes NOTHING. StringHttpMessageConverter supports
        // MediaType.ALL and sits ahead of the Jackson converter in the list, so it claims the
        // write even when you ask for application/json. There is no way to make send() quote a
        // String -- which is good news if you are streaming pre-rendered JSON, and a trap if you
        // expected a String field to be escaped for you.
        assertThat(stringPlain).isEqualTo("{\"already\":\"json\"}");
        assertThat(stringJson).isEqualTo(stringPlain);
    }

    private static String dataAfter(List<String> lines, String eventLine) {
        int i = lines.indexOf(eventLine);
        assertThat(i).as("event line %s present", eventLine).isGreaterThanOrEqualTo(0);
        for (int j = i; j < lines.size(); j++) {
            if (lines.get(j).startsWith("data:")) {
                return lines.get(j).substring("data:".length());
            }
        }
        throw new AssertionError("no data line after " + eventLine);
    }
}