package tech.nevets.wikipediabot;

import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;

import java.io.IOException;
import java.net.URI;
import java.net.URLEncoder;
import java.net.http.HttpClient;
import java.net.http.HttpHeaders;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.charset.StandardCharsets;

public class WikipediaRequest {
    private static final Gson GSON = new Gson();

    public static String wikipediaRequest(String topic) {
        String topicProper = topic.replaceAll(" ", "_");
        String strRes = wikiApiCall("https://en.wikipedia.org/api/rest_v1/page/summary/" + topicProper);

        JsonObject res = GSON.fromJson(strRes, JsonObject.class);
        if (res.get("title").getAsString().equals("Not found.")) {
            JsonArray altRes = GSON.fromJson(wikiApiCall("https://en.wikipedia.org/w/api.php?action=opensearch&search=" + URLEncoder.encode(topic, StandardCharsets.UTF_8) + "&namespace=0&format=json"), JsonArray.class);
            JsonArray similarList = altRes.get(1).getAsJsonArray();
            if (similarList.size() == 0) {
                return "Cannot find topic \"" + topic + "\", please try a different spelling.";
            }
            StringBuilder sb = new StringBuilder();
            sb.append("Topic not found, did you mean:\n");
            for (JsonElement similarItem : similarList) {
                sb.append("- ").append(similarItem.getAsString()).append("\n");
            }
            return sb.toString();
        }
        return res.get("extract").getAsString();
    }

    private static String wikiApiCall(String url) {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .GET()
                .header("Accept", "application/json")
                .uri(URI.create(url))
                .build();
        HttpResponse<String> response;
        try {
            response = client.send(request, HttpResponse.BodyHandlers.ofString());
            HttpHeaders headers = response.headers();
            if ((response.statusCode() > 299 && response.statusCode() < 400) && headers.firstValue("location").isPresent()) {
                return followRedirect(headers.firstValue("location").get());
            }
            return response.body();
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
            return "Error making request: " + e.getMessage();
        }
    }

    private static String followRedirect(String redirectedUrl) {
        return wikiApiCall("https://en.wikipedia.org/api/rest_v1/page/summary/" + redirectedUrl);
    }
}