package domain

import "strings"

const (
	SuggestUsageInclude = "include"
	SuggestUsageExclude = "exclude"

	// 建議數量上限：清單要能一眼看完並逐條決定，不是丟一大串讓人放棄。
	MaxSuggestions     = 20
	DefaultSuggestions = 8
)

/*
WatchTermSuggestion 是一則關鍵字建議。

Reason 是必填的：使用者要逐條決定採不採用，看不到「為什麼建議這個詞」就只能全採或全不採，
那這個功能就退化成一個猜測產生器。
*/
type WatchTermSuggestion struct {
	Term   string `json:"term"`
	Reason string `json:"reason"`
	Usage  string `json:"usage"`
}

func NormalizeSuggestUsage(s string) string {
	if strings.EqualFold(strings.TrimSpace(s), SuggestUsageExclude) {
		return SuggestUsageExclude
	}
	return SuggestUsageInclude
}

/*
CleanSuggestions 收掉空白與重複，丟掉沒有理由的項目，並套用數量上限。

沒有理由的項目直接丟：補一句「AI 建議」等於假裝有理由，比少一則更糟。
*/
func CleanSuggestions(in []WatchTermSuggestion, limit int) []WatchTermSuggestion {
	if limit <= 0 || limit > MaxSuggestions {
		limit = MaxSuggestions
	}
	out := make([]WatchTermSuggestion, 0, len(in))
	seen := map[string]bool{}
	for _, s := range in {
		term := strings.ToLower(strings.Join(strings.Fields(strings.ReplaceAll(s.Term, "\u3000", " ")), " "))
		reason := strings.TrimSpace(s.Reason)
		if term == "" || reason == "" {
			continue
		}
		if len([]rune(term)) < MinTermLen || len([]rune(term)) > MaxTermLen {
			continue
		}
		if seen[term] {
			continue
		}
		seen[term] = true
		out = append(out, WatchTermSuggestion{Term: term, Reason: reason, Usage: NormalizeSuggestUsage(s.Usage)})
		if len(out) >= limit {
			break
		}
	}
	return out
}