package com.hlab.yanalyst.domain.channel;

import com.hlab.yanalyst.web.dto.YoutubeSearchResultDto;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

/** 검색된 Shorts 목록 → 채널별 최고 배율 후보 집계·필터·정렬(순수 로직). */
public final class DiscoveryRanker {

    private DiscoveryRanker() {}

    public record Candidate(String channelId, String channelTitle, String thumbnailUrl, Long subscriberCount,
                            String topVideoId, String topVideoTitle, Long topVideoViewCount,
                            double ratio, String region) {}

    public static List<Candidate> rank(List<YoutubeSearchResultDto> items, long maxSubscribers,
                                       double minRatio, Set<String> excludeChannelIds) {
        Map<String, Candidate> best = new LinkedHashMap<>();
        for (YoutubeSearchResultDto it : items) {
            String ch = it.getChannelId();
            Long subs = it.getSubscriberCount();
            Long views = it.getViewCount();
            if (ch == null || subs == null || subs <= 0 || views == null) continue;
            if (excludeChannelIds.contains(ch)) continue;
            if (subs > maxSubscribers) continue;

            double ratio = (double) views / subs;
            if (ratio < minRatio) continue;

            Candidate prev = best.get(ch);
            if (prev == null || ratio > prev.ratio()) {
                best.put(ch, new Candidate(ch, it.getChannelTitle(), it.getThumbnailUrl(), subs,
                        it.getVideoId(), it.getTitle(), views, ratio, it.getChannelCountry()));
            }
        }
        List<Candidate> out = new ArrayList<>(best.values());
        out.sort(Comparator.comparingDouble(Candidate::ratio).reversed());
        return out;
    }
}