java/w10/strategy/StrategyFactory.java

package com.example.datacollect.strategy;

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;

public class StrategyFactory {
    private final List<CrawlStrategy> strategies = new ArrayList<>();
    private CrawlStrategy defaultStrategy;

    public StrategyFactory() {
        strategies.add(new HnuNewsStrategy());
        strategies.add(new BlogStrategy());
        strategies.add(new NewsStrategy());
        strategies.add(new GenericNewsStrategy());
        defaultStrategy = new DefaultStrategy();
    }

    public CrawlStrategy getStrategy(String url) {
        CrawlStrategy matched = null;
        int highestPriority = Integer.MIN_VALUE;

        for (CrawlStrategy s : strategies) {
            boolean supports = false;
            
            Pattern pattern = s.getPattern();
            if (pattern != null) {
                supports = pattern.matcher(url).find();
            } else {
                supports = s.supports(url);
            }

            if (supports) {
                int priority = s.getPriority();
                if (priority > highestPriority) {
                    highestPriority = priority;
                    matched = s;
                }
            }
        }

        if (matched != null) {
            return matched;
        }

        return defaultStrategy;
    }

    public void register(CrawlStrategy strategy) {
        strategies.add(strategy);
    }

    public void register(CrawlStrategy strategy, int priority) {
        strategies.add(new PrioritizedStrategy(strategy, priority));
    }

    public void setDefaultStrategy(CrawlStrategy defaultStrategy) {
        this.defaultStrategy = defaultStrategy;
    }

    private static class PrioritizedStrategy implements CrawlStrategy {
        private final CrawlStrategy delegate;
        private final int priority;

        public PrioritizedStrategy(CrawlStrategy delegate, int priority) {
            this.delegate = delegate;
            this.priority = priority;
        }

        @Override
        public List<Article> parse(String url, Document doc) {
            return delegate.parse(url, doc);
        }

        @Override
        public boolean supports(String url) {
            return delegate.supports(url);
        }

        @Override
        public int getPriority() {
            return priority;
        }

        @Override
        public Pattern getPattern() {
            return delegate.getPattern();
        }
    }

    private static class DefaultStrategy implements CrawlStrategy {
        @Override
        public List<Article> parse(String url, Document doc) {
            return List.of();
        }

        @Override
        public boolean supports(String url) {
            return false;
        }

        @Override
        public int getPriority() {
            return Integer.MIN_VALUE;
        }
    }
}