package com.ankurm.ssews;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

/**
 * A raw-socket SSE client.
 *
 * <p>Deliberately not an HTTP client library: the article quotes the bytes on the wire, and any
 * client that parses events for you hides exactly the thing being shown. It also lets a test
 * abandon the socket mid-stream, which is how the disconnect case is reproduced.
 */
final class SseClient implements AutoCloseable {

    private final Socket socket;
    private final BufferedReader reader;
    private final List<String> lines = new ArrayList<>();

    SseClient(int port, String path) throws Exception {
        this(port, path, null);
    }

    SseClient(int port, String path, String lastEventId) throws Exception {
        this.socket = new Socket("127.0.0.1", port);
        this.socket.setSoTimeout(15_000);
        StringBuilder req = new StringBuilder()
                .append("GET ").append(path).append(" HTTP/1.1\r\n")
                .append("Host: 127.0.0.1:").append(port).append("\r\n")
                .append("Accept: text/event-stream\r\n");
        if (lastEventId != null) {
            req.append("Last-Event-ID: ").append(lastEventId).append("\r\n");
        }
        req.append("Connection: close\r\n\r\n");
        OutputStream out = socket.getOutputStream();
        out.write(req.toString().getBytes(StandardCharsets.UTF_8));
        out.flush();
        this.reader = new BufferedReader(new InputStreamReader(socket.getInputStream(), StandardCharsets.UTF_8));
    }

    /** Read until the stream closes or {@code max} lines have arrived. Records everything. */
    List<String> read(int max) throws Exception {
        String line;
        while (lines.size() < max && (line = reader.readLine()) != null) {
            lines.add(line);
        }
        return List.copyOf(lines);
    }

    /** Read everything until the server closes the connection. */
    List<String> readToEnd() throws Exception {
        String line;
        while ((line = reader.readLine()) != null) {
            lines.add(line);
        }
        return List.copyOf(lines);
    }

    List<String> lines() {
        return List.copyOf(lines);
    }

    @Override
    public void close() throws Exception {
        socket.close();
    }
}