package cn.edu.bjut.textmining.util;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;

/**
 * UTF-8 文件读写工具类。
 */
public final class FileUtil {
	public static Path path(String first, String... more) {
		return Paths.get(first, more);
	}

	public static List<String> readUtf8Lines(Path path) {
		return readLines(path, StandardCharsets.UTF_8);
	}

	public static List<String> readNonEmptyUtf8Lines(Path path) {
		List<String> lines = readUtf8Lines(path);
		List<String> result = new ArrayList<String>();
		for (String line : lines) {
			if (line != null && line.trim().length() > 0) {
				result.add(line);
			}
		}
		return result;
	}

	public static List<String> readLines(Path path, Charset charset) {
		List<String> result = new ArrayList<String>();
		try (BufferedReader reader = Files.newBufferedReader(path, charset)) {
			for (String line; (line = reader.readLine()) != null;) {
				result.add(line);
			}
		} catch (IOException e) {
			throw new UncheckedIOException("读取文件失败：" + path.toAbsolutePath(), e);
		}
		return result;
	}

	public static String readUtf8Text(Path path) {
		List<String> lines = readUtf8Lines(path);
		StringBuilder builder = new StringBuilder();
		for (int i = 0; i < lines.size(); i++) {
			builder.append(lines.get(i));
			if (i < lines.size() - 1) {
				builder.append(System.lineSeparator());
			}
		}
		return builder.toString();
	}

	public static void writeUtf8Text(Path path, String content) {
		try {
			Path parent = path.getParent();
			if (parent != null) {
				Files.createDirectories(parent);
			}
			try (BufferedWriter writer = Files.newBufferedWriter(path, StandardCharsets.UTF_8)) {
				writer.write(content);
			}
		} catch (IOException e) {
			throw new UncheckedIOException("写入文件失败：" + path.toAbsolutePath(), e);
		}
	}
}