package com.crawler.util;

import com.crawler.model.Article;

import java.io.*;
import java.nio.charset.StandardCharsets;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.List;

public class DataPersistence {
    private static final String DATA_FOLDER = "data";
    private static final String INDEX_FILE = DATA_FOLDER + File.separator + "index.txt";
    private static final DateTimeFormatter DATE_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

    static {
        File folder = new File(DATA_FOLDER);
        if (!folder.exists()) {
            folder.mkdirs();
        }
    }

    public static void saveArticles(List<Article> articles) {
        try {
            for (Article article : articles) {
                saveSingleArticle(article);
            }
            saveIndex(articles);
            System.out.println(ColorUtil.green("✓ Saved " + articles.size() + " articles to '" + DATA_FOLDER + "' folder"));
        } catch (Exception e) {
            System.err.println(ColorUtil.red("✗ Failed to save articles: " + e.getMessage()));
        }
    }

    private static void saveSingleArticle(Article article) throws IOException {
        String filename = DATA_FOLDER + File.separator + "article_" + article.getId() + ".txt";
        try (BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(filename), StandardCharsets.UTF_8))) {
            writer.write("========================================\n");
            writer.write("           文章详细信息\n");
            writer.write("========================================\n\n");
            writer.write("ID: " + article.getId() + "\n");
            writer.write("标题: " + article.getTitle() + "\n");
            writer.write("URL: " + article.getUrl() + "\n");
            if (article.getAuthor() != null) {
                writer.write("作者: " + article.getAuthor() + "\n");
            }
            if (article.getSource() != null) {
                writer.write("来源: " + article.getSource() + "\n");
            }
            if (article.getPublishDate() != null) {
                writer.write("发布时间: " + article.getPublishDate().format(DATE_FORMATTER) + "\n");
            }
            writer.write("爬取时间: " + article.getCrawlDate().format(DATE_FORMATTER) + "\n");
            writer.write("\n========================================\n");
            writer.write("           文章内容\n");
            writer.write("========================================\n");
            if (article.getContent() != null) {
                writer.write(article.getContent());
            }
            writer.write("\n\n");
        }
    }

    private static void saveIndex(List<Article> articles) throws IOException {
        try (BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(INDEX_FILE), StandardCharsets.UTF_8))) {
            writer.write("========================================\n");
            writer.write("           文章索引\n");
            writer.write("========================================\n\n");
            writer.write("共有 " + articles.size() + " 篇文章\n\n");
            
            for (Article article : articles) {
                writer.write("[" + article.getId() + "] " + article.getTitle() + "\n");
                writer.write("    URL: " + article.getUrl() + "\n");
                writer.write("    文件名: article_" + article.getId() + ".txt\n");
                if (article.getCrawlDate() != null) {
                    writer.write("    爬取时间: " + article.getCrawlDate().format(DATE_FORMATTER) + "\n");
                }
                writer.write("\n");
            }
        }
    }

    public static List<Article> loadArticles() {
        List<Article> articles = new ArrayList<>();
        File indexFile = new File(INDEX_FILE);
        if (!indexFile.exists()) {
            return articles;
        }

        File folder = new File(DATA_FOLDER);
        File[] files = folder.listFiles((dir, name) -> name.startsWith("article_") && name.endsWith(".txt"));
        
        if (files != null) {
            for (File file : files) {
                try {
                    Article article = loadSingleArticle(file);
                    if (article != null) {
                        articles.add(article);
                    }
                } catch (Exception e) {
                    System.err.println(ColorUtil.yellow("⚠ 无法加载文件: " + file.getName()));
                }
            }
        }

        System.out.println(ColorUtil.green("✓ Loaded " + articles.size() + " articles from '" + DATA_FOLDER + "' folder"));
        return articles;
    }

    private static Article loadSingleArticle(File file) throws IOException {
        Article article = new Article();
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(file), StandardCharsets.UTF_8))) {
            String line;
            StringBuilder content = new StringBuilder();
            boolean inContent = false;
            
            while ((line = reader.readLine()) != null) {
                if (line.contains("文章内容")) {
                    inContent = true;
                    // Skip the next separator line
                    reader.readLine();
                    continue;
                }
                
                if (!inContent) {
                    if (line.startsWith("ID: ")) {
                        article.setId(line.substring(4));
                    } else if (line.startsWith("标题: ")) {
                        article.setTitle(line.substring(4));
                    } else if (line.startsWith("URL: ")) {
                        article.setUrl(line.substring(5));
                    } else if (line.startsWith("作者: ")) {
                        article.setAuthor(line.substring(4));
                    } else if (line.startsWith("来源: ")) {
                        article.setSource(line.substring(4));
                    }
                } else {
                    if (content.length() > 0) {
                        content.append("\n");
                    }
                    content.append(line);
                }
            }
            
            if (content.length() > 0) {
                article.setContent(content.toString());
            }
        }
        return article;
    }
}