refactor: split subscription planner modules

internal/service/subscription_candidate_select.go

@@ -0,0 +1,124 @@
+package service
+
+import (
+	"sort"
+
+	"github.com/ShukeBta/MediaStationGo/internal/model"
+)
+
+func selectPreparedSubscriptionCandidates(candidates []siteSearchCandidate, sub *model.Subscription, local LocalAvailability) []siteSearchCandidate {
+	return selectPreparedSubscriptionCandidatesWithStats(candidates, sub, local, nil)
+}
+
+func selectPreparedSubscriptionCandidatesWithStats(candidates []siteSearchCandidate, sub *model.Subscription, local LocalAvailability, stats *siteSearchSelectionStats) []siteSearchCandidate {
+	if len(candidates) > 1 {
+		sort.SliceStable(candidates, func(i, j int) bool {
+			if candidates[i].Score != candidates[j].Score {
+				return candidates[i].Score > candidates[j].Score
+			}
+			if candidates[i].Item.Seeders != candidates[j].Item.Seeders {
+				return candidates[i].Item.Seeders > candidates[j].Item.Seeders
+			}
+			return candidates[i].Item.Size > candidates[j].Item.Size
+		})
+	}
+	if len(candidates) == 0 {
+		return recordPreparedSelection(nil, stats)
+	}
+
+	mediaType := normalizeMediaType(sub.MediaType, sub.Name+" "+sub.Filter, "")
+	if !isSubscriptionSeriesType(mediaType) {
+		// 非洗版订阅成功下载一次即满足，媒体库/下载中已存在则不再重复下载。
+		if (sub == nil || !sub.WashEnabled) && local.LocalMediaCount > 0 {
+			if stats != nil {
+				stats.LocalAlreadySatisfied = true
+			}
+			return recordPreparedSelection(nil, stats)
+		}
+		return recordPreparedSelection(candidates[:1], stats)
+	}
+
+	if local.HasSeriesPack {
+		if stats != nil {
+			stats.LocalSeriesPackPresent = true
+		}
+		return recordPreparedSelection(nil, stats)
+	}
+	if local.LocalMediaCount > 0 {
+		if local.TotalEpisodes > 0 && len(local.MissingEpisodes) == 0 {
+			if stats != nil {
+				stats.SeriesComplete = true
+			}
+			return recordPreparedSelection(nil, stats)
+		}
+		missingSet := missingEpisodeSet(local)
+		onlyMissing := make([]siteSearchCandidate, 0, len(candidates))
+		var packFallback *siteSearchCandidate
+		for i := range candidates {
+			candidate := candidates[i]
+			if candidate.Episode <= 0 {
+				// 整季/全集包(无单集号)。剧集完结后站点常只挂全集包,
+				// 这里记下来作兜底:当单集候选不足以补齐缺失集时启用,
+				// 否则"补全缺失集"在站点只有全集包时永远匹配为空。
+				if stats != nil {
+					stats.NoEpisodeSkipped++
+				}
+				if candidate.Pack && packFallback == nil {
+					packFallback = &candidates[i]
+					if stats != nil {
+						stats.PackFallbackAvailable = true
+					}
+				}
+				continue
+			}
+			season := candidate.Season
+			if season <= 0 {
+				season = 1
+			}
+			if _, exists := local.ExistingEpisodeKeys[episodeKey(season, candidate.Episode)]; exists {
+				if stats != nil {
+					stats.ExistingEpisodeSkipped++
+				}
+				continue
+			}
+			if local.TotalEpisodes > 0 {
+				if _, missing := missingSet[candidate.Episode]; !missing {
+					if stats != nil {
+						stats.NotMissingEpisodeSkipped++
+					}
+					continue
+				}
+			}
+			onlyMissing = append(onlyMissing, candidate)
+		}
+		selected := sortedEpisodeCandidates(onlyMissing)
+		if len(selected) == 0 && packFallback != nil {
+			// 没有可用的单集候选,但站点有整季/全集包 → 用包兜底补缺集。
+			// 代价是会重下已有集,但用户主动触发补全时这是可接受的。
+			if stats != nil {
+				stats.PackFallbackUsed = true
+			}
+			return recordPreparedSelection([]siteSearchCandidate{*packFallback}, stats)
+		}
+		return recordPreparedSelection(selected, stats)
+	}
+
+	for _, candidate := range candidates {
+		if candidate.Pack {
+			return recordPreparedSelection([]siteSearchCandidate{candidate}, stats)
+		}
+	}
+
+	selected := sortedEpisodeCandidates(candidates)
+	if len(selected) == 0 {
+		return recordPreparedSelection(candidates[:1], stats)
+	}
+	return recordPreparedSelection(selected, stats)
+}
+
+func recordPreparedSelection(candidates []siteSearchCandidate, stats *siteSearchSelectionStats) []siteSearchCandidate {
+	if stats != nil {
+		stats.Selected = len(candidates)
+	}
+	return candidates
+}