package se.bilhalsning.service;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;
import se.bilhalsning.dto.VehicleInfoResponse;
import se.bilhalsning.exception.VehicleLookupException;
import se.bilhalsning.exception.VehicleNotFoundException;

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.Map;

@Service
public class VehicleLookupService {

    private static final Logger log = LoggerFactory.getLogger(VehicleLookupService.class);
    private static final String BASE_URL = "https://biluppgifter.se/fordon";

    public VehicleInfoResponse lookup(String plate) {
        Document doc = fetchPage(plate);
        Map<String, String> fields = new LinkedHashMap<>();

        extractSummaryFields(doc, fields);
        extractDataSectionFields(doc, fields);

        if (fields.isEmpty() || !fields.containsKey("Fabrikat")) {
            throw new VehicleNotFoundException(plate);
        }

        String make = fields.getOrDefault("Fabrikat", "");
        String model = buildModel(fields);
        int year = parseYearFromFields(fields);
        String color = fields.getOrDefault("Färg", "");
        String fuel = fields.getOrDefault("Bränsle", "");

        return new VehicleInfoResponse(make, model, year, color, fuel);
    }

    Document fetchPage(String plate) {
        String url = BASE_URL + "/" + plate.toLowerCase() + "/";
        try {
            return Jsoup.connect(url)
                    .userAgent("BilHej/1.0")
                    .timeout(10_000)
                    .get();
        } catch (IOException e) {
            log.warn("Failed to fetch vehicle data for plate {}", plate, e);
            throw new VehicleLookupException("Failed to fetch vehicle data", e);
        }
    }

    void extractSummaryFields(Document doc, Map<String, String> fields) {
        Elements infoDivs = doc.select(".info > em");
        for (Element em : infoDivs) {
            Element span = em.nextElementSibling();
            if (span != null && span.tagName().equals("span")) {
                String label = span.text().trim();
                String value = em.ownText().trim();
                if (!label.isEmpty() && !value.isEmpty()) {
                    fields.putIfAbsent(label, value);
                }
            }
        }
    }

    void extractDataSectionFields(Document doc, Map<String, String> fields) {
        Element heading = doc.selectFirst("h2:containsOwn(Fordonsdata)");
        if (heading == null) {
            return;
        }

        Element section = findParentSection(heading);
        if (section == null) {
            return;
        }

        Elements listItems = section.select("ul.list > li");
        for (Element li : listItems) {
            Element labelEl = li.selectFirst("span.label");
            Element valueEl = li.selectFirst("span.value");
            if (labelEl != null && valueEl != null) {
                String label = labelEl.text().trim();
                String value = valueEl.text().trim();
                if (!label.isEmpty() && !value.isEmpty() && !value.equals("Logga in")) {
                    fields.putIfAbsent(label, value);
                }
            }
        }
    }

    Map<String, String> extractFields(Document doc) {
        Map<String, String> fields = new LinkedHashMap<>();
        extractSummaryFields(doc, fields);
        extractDataSectionFields(doc, fields);
        return fields;
    }

    private Element findParentSection(Element heading) {
        Element current = heading.parent();
        while (current != null) {
            if ("section".equals(current.tagName())) {
                return current;
            }
            current = current.parent();
        }
        return heading.parent();
    }

    private String buildModel(Map<String, String> fields) {
        String model = fields.getOrDefault("Modell", "");
        String variant = fields.getOrDefault("Variant", "");

        if (!model.isEmpty() && !variant.isEmpty()) {
            return model + " " + variant;
        }
        return model.isEmpty() ? variant : model;
    }

    private int parseYearFromFields(Map<String, String> fields) {
        String yearText = fields.getOrDefault("Fordonsår / Modellår", "");
        if (yearText.isEmpty()) {
            yearText = fields.getOrDefault("Modellår", "");
        }

        if (yearText.isEmpty()) {
            return 0;
        }

        String[] parts = yearText.split("/");
        try {
            return Integer.parseInt(parts[0].trim());
        } catch (NumberFormatException e) {
            return 0;
        }
    }
}