package com.tsystems.inwo.vgl.service;

import com.fasterxml.jackson.databind.JsonNode;
import org.springframework.stereotype.Service;

import java.util.Objects;
import java.util.function.Function;

@Service
public class HtmlRenderingService {

    public String buildPersonFieldHtml(JsonNode rightPerson, JsonNode leftPerson, Function<JsonNode, String> extractor, boolean hasChanges) {
        if (!hasChanges || rightPerson == null) {
            JsonNode primary = rightPerson != null ? rightPerson : leftPerson;
            return primary != null ? escape(extractor.apply(primary)) : "";
        }
        
        String rightVal = rightPerson != null ? extractor.apply(rightPerson) : "";
        String leftVal = leftPerson != null ? extractor.apply(leftPerson) : "";
        
        if (!Objects.equals(rightVal, leftVal)) {
            return cellHtml(rightVal, leftVal, true);
        } else {
            return escape(rightVal);
        }
    }
    
    public String buildItemFieldHtml(JsonNode rightItem, JsonNode leftItem, Function<JsonNode, String> extractor, boolean hasChanges) {
        if (!hasChanges || rightItem == null) {
            JsonNode primary = rightItem != null ? rightItem : leftItem;
            return primary != null ? escape(extractor.apply(primary)) : "";
        }
        
        String rightVal = rightItem != null ? extractor.apply(rightItem) : "";
        String leftVal = leftItem != null ? extractor.apply(leftItem) : "";
        
        if (!Objects.equals(rightVal, leftVal)) {
            return cellHtml(rightVal, leftVal, true);
        } else {
            return escape(rightVal);
        }
    }

    public String buildEinkommenFieldHtml(JsonNode rightItem, JsonNode leftItem, Function<JsonNode, String> extractor, boolean hasChanges) {
        if (!hasChanges || rightItem == null) {
            JsonNode primary = rightItem != null ? rightItem : leftItem;
            return primary != null ? escape(extractor.apply(primary)) : "";
        }
        
        String rightVal = rightItem != null ? extractor.apply(rightItem) : "";
        String leftVal = leftItem != null ? extractor.apply(leftItem) : "";
        
        if (!Objects.equals(rightVal, leftVal)) {
            return cellHtml(rightVal, leftVal, true);
        } else {
            return escape(rightVal);
        }
    }

    public String buildFreibetragFieldHtml(JsonNode rightItem, JsonNode leftItem, Function<JsonNode, String> extractor, boolean hasChanges) {
        if (!hasChanges || rightItem == null) {
            JsonNode primary = rightItem != null ? rightItem : leftItem;
            return primary != null ? escape(extractor.apply(primary)) : "";
        }
        
        String rightVal = rightItem != null ? extractor.apply(rightItem) : "";
        String leftVal = leftItem != null ? extractor.apply(leftItem) : "";
        
        if (!Objects.equals(rightVal, leftVal)) {
            return cellHtml(rightVal, leftVal, true);
        } else {
            return escape(rightVal);
        }
    }

    public String buildKitaFieldHtml(JsonNode rightItem, JsonNode leftItem, Function<JsonNode, String> extractor, boolean hasChanges) {
        if (!hasChanges || rightItem == null) {
            JsonNode primary = rightItem != null ? rightItem : leftItem;
            return primary != null ? escape(extractor.apply(primary)) : "";
        }
        
        String rightVal = rightItem != null ? extractor.apply(rightItem) : "";
        String leftVal = leftItem != null ? extractor.apply(leftItem) : "";
        
        if (!Objects.equals(rightVal, leftVal)) {
            return cellHtml(rightVal, leftVal, true);
        } else {
            return escape(rightVal);
        }
    }

    public String cellHtml(String newVal, String oldVal, boolean changed) {
        if (!changed) {
            return escape(newVal);
        }
        
        // Handle empty old values
        String displayOldVal = (oldVal == null || oldVal.trim().isEmpty()) ? "leer" : oldVal;
        
        // Return with cell-changed class and proper old value display
        return "<span class='cell-changed'>" + escape(newVal) + 
               "<div class='old'>Alt: " + escape(displayOldVal) + "</div></span>";
    }
    
    public String escape(String s) {
        if (s == null) return "";
        return s.replace("&", "&")
                .replace("<", "<")
                .replace(">", ">");
    }
}