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package com.zandero.template;

import com.fasterxml.jackson.databind.JsonNode;
import com.github.mustachejava.DefaultMustacheFactory;
import com.github.mustachejava.Mustache;
import com.github.mustachejava.MustacheFactory;
import com.zandero.utils.Assert;
import com.zandero.utils.ResourceUtils;
import com.zandero.utils.extra.JsonUtils;

import java.io.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

/**
 * Helper class wrapping Mustache template engine
 */
public class MustacheUtils {

	private static ThreadLocal factory;

	public MustacheUtils() {

	}

	public Mustache compile(String template, String path) {

		Assert.notNull(template, "Missing template!");
		MustacheFactory mf = getFactory();
		return mf.compile(new StringReader(template), path);
	}

	public Mustache load(String path) {

		Assert.notNullOrEmptyTrimmed(path, "Missing template path!");

		InputStream resource = this.getClass().getResourceAsStream(path);
		Assert.notNull(resource, "Could not load template: '" + path + "'");

		String content = ResourceUtils.getString(resource);

		MustacheFactory mf = getFactory();
		return mf.compile(new StringReader(content), path);
	}

	public Mustache loadFile(String path) {

		Assert.notNullOrEmptyTrimmed(path, "Missing template file path!");

		File file = new File(path);
		Assert.isTrue(file.exists(), "File not found: '" + path + "'");

		try {
			String content = ResourceUtils.readFileToString(file);
			MustacheFactory mf = getFactory();
			return mf.compile(new StringReader(content), path);
		}
		catch (IOException e) {
			throw new IllegalArgumentException("Failed to load file: '" + file + "' " + e.getMessage());
		}
	}

	public String render(Mustache template, Object data) {

		Assert.notNull(template, "Missing template!");

		StringWriter out = new StringWriter();
		Object mustacheObject = data;
		if ((data != null) && (data instanceof JsonNode)) {
			mustacheObject = toMustacheObject((JsonNode) data);
		}

		template.execute(out, mustacheObject); // apply mustache template
		return out.toString();
	}

	public String renderStrings(Mustache template, String... data) {

		Assert.notNull(template, "Missing template!");

		Map map = new HashMap<>();
		int count = 0;
		String name = null;

		for (String item: data) {
			if (count % 2 == 1) {
				map.put(name, item);
			}
			else {
				name = item;
			}
			count ++;
		}

		StringWriter out = new StringWriter();
		template.execute(out, map); // apply mustache template
		return out.toString();
	}

	public String renderJson(Mustache template, String dataAsJson) {

		Assert.notNull(template, "Missing template!");

		Map data = JsonUtils.fromJsonAsMap(dataAsJson, String.class, Object.class);

		StringWriter out = new StringWriter();
		template.execute(out, data); // apply mustache template
		return out.toString();
	}

	/**
	 * code copied from https://github.com/spullara/mustache.java/blob/master/handlebar/src/main/java/com/sampullara/mustache/Handlebar.java
	 * converts a tree of JsonNode objects to nested HashMaps, which are used by mustache template engine
	 *
	 * @param node to convert
	 * @return mustache object node
	 */
	private static Object toMustacheObject(final JsonNode node) {

		if (node.isArray()) {
			return new ArrayList