import java.util.function.Supplier;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Pattern;

// ─────────────────────────────────────────────
// Command 接口
// ─────────────────────────────────────────────
interface Command {
    String getName();
    void execute(String[] args, List<Article> articles);
}

// ─────────────────────────────────────────────
// HelpCommand
// ─────────────────────────────────────────────
class HelpCommand implements Command {
    private final ConsoleView view;
    HelpCommand(ConsoleView v) { this.view = v; }

    @Override public String getName() { return "help"; }

    @Override
    public void execute(String[] args, List<Article> articles) {
        view.printInfo("可用命令：");
        view.printInfo("  crawl <url>  抓取 URL（别名: c）");
        view.printInfo("  list         列出所有文章");
        view.printInfo("  analyze      策略命中统计");
        view.printInfo("  history      历史命令记录");
        view.printInfo("  help         显示帮助");
        view.printInfo("  exit         退出");
    }
}

// ─────────────────────────────────────────────
// ListCommand
// ─────────────────────────────────────────────
class ListCommand implements Command {
    private final ConsoleView       view;
    private final ArticleRepository repo;
    ListCommand(ConsoleView v, ArticleRepository r) { view = v; repo = r; }

    @Override public String getName() { return "list"; }

    @Override
    public void execute(String[] args, List<Article> ignored) {
        view.display(repo.getAll());
    }
}

// ─────────────────────────────────────────────
// CrawlCommand（W11升级：异常体系 + 指数退避 + 断路器）
// ─────────────────────────────────────────────
class CrawlCommand implements Command {
    private final ConsoleView        view;
    private final ArticleRepository  repo;
    private final StrategySelector   selector;
    // 选做：断路器，连续失败3次熔断，冷却10秒
    private final CircuitBreaker     breaker = new CircuitBreaker(3, 10_000);

    private static final Pattern URL_PAT =
        Pattern.compile("^https?://[^\\s/$.?#].[^\\s]*$");

    CrawlCommand(ConsoleView v, ArticleRepository r, StrategySelector s) {
        view = v; repo = r; selector = s;
    }

    @Override public String getName()  { return "crawl"; }
    public        String getAlias()    { return "c"; }

    @Override
    public void execute(String[] args, List<Article> ignored) {
        if (args.length < 2 || args[1].isBlank()) {
            view.printError("用法：crawl <url>");
            return;
        }
        String url = args[1].trim();

        // 必做1：URL 格式校验改为抛出 UrlFormatException（Unchecked）
        try {
            validateUrl(url);
        } catch (UrlFormatException e) {
            view.printError(e.getMessage());
            return;
        }

        if (repo.findByUrl(url) != null) {
            view.printWarning("已抓取过，跳过：" + url);
            return;
        }

        ParseStrategy strategy = selector.select(url);
        if (strategy == null) {
            view.printError("无可用策略：" + url);
            return;
        }

        // 必做2：指数退避重试 + 选做：断路器保护
        final ParseStrategy finalStrategy = strategy;
        boolean success = RetryUtils.retryWithFastFail(() ->
            breaker.call(() -> {
                Article article = finalStrategy.parse(url);
                repo.add(article);
                view.printSuccess("已抓取 [" + finalStrategy.getName() + "]：" + article.getTitle());
                return true;
            }), 3
        );

        if (!success) {
            view.printError("抓取失败（已重试/熔断）：" + url);
            if (breaker.getState() == CircuitBreaker.State.OPEN) {
                view.printWarning("断路器已熔断，请稍后再试。");
            }
        }
    }

    /** 必做1：集中校验，校验失败抛 UrlFormatException */
    private void validateUrl(String url) {
        if (!URL_PAT.matcher(url).matches()) {
            throw new UrlFormatException(url);
        }
    }
}

// ─────────────────────────────────────────────
// AnalyzeCommand
// ─────────────────────────────────────────────
class AnalyzeCommand implements Command {
    private final ConsoleView      view;
    private final ArticleRepository repo;
    private final StrategySelector selector;

    AnalyzeCommand(ConsoleView v, ArticleRepository r, StrategySelector s) {
        view = v; repo = r; selector = s;
    }

    @Override public String getName() { return "analyze"; }

    @Override
    public void execute(String[] args, List<Article> ignored) {
        List<Article> all = repo.getAll();
        if (all.isEmpty()) { view.printWarning("暂无文章。"); return; }

        Map<String, Integer> hits = new HashMap<>();
        int unmatched = 0;
        for (Article a : all) {
            ParseStrategy s = selector.select(a.getUrl());
            if (s == null) unmatched++;
            else           hits.merge(s.getName(), 1, Integer::sum);
        }

        view.printBold("── 策略分析报告（共 " + all.size() + " 篇）──");
        for (ParseStrategy s : selector.getAll()) {
            view.printInfo(String.format("  %-25s priority=%-4d 命中 %d 篇",
                    s.getName(), s.getPriority(), hits.getOrDefault(s.getName(), 0)));
        }
        if (unmatched > 0) view.printWarning("无策略匹配：" + unmatched + " 篇");
    }
}

// ─────────────────────────────────────────────
// HistoryCommand
// ─────────────────────────────────────────────
class HistoryCommand implements Command {
    private final ConsoleView  view;
    private final List<String> history;
    HistoryCommand(ConsoleView v, List<String> h) { view = v; history = h; }

    @Override public String getName() { return "history"; }

    @Override
    public void execute(String[] args, List<Article> ignored) {
        if (history.isEmpty()) { view.printInfo("暂无历史记录。"); return; }
        view.printBold("── 历史命令（共 " + history.size() + " 条）──");
        for (int i = 0; i < history.size(); i++)
            view.printInfo(String.format("%3d  %s", i + 1, history.get(i)));
    }
}

// ─────────────────────────────────────────────
// ExitCommand
// ─────────────────────────────────────────────
class ExitCommand implements Command {
    private final ConsoleView view;
    ExitCommand(ConsoleView v) { this.view = v; }

    @Override public String getName() { return "exit"; }

    @Override
    public void execute(String[] args, List<Article> ignored) {
        view.printSuccess("Bye!");
        System.exit(0);
    }
}