package viral

import (
	"strings"

	"haixun-backend/internal/library/placement"
)

const (
	MinEngagementScore = 24
	MinLikeCount       = 8
	HotEngagementScore = 80
)

// ScorePost ranks viral imitation candidates by engagement signals.
func ScorePost(likes, replies int) int {
	if likes < 0 {
		likes = 0
	}
	if replies < 0 {
		replies = 0
	}
	score := likes*2 + replies*3
	if likes >= 20 && replies >= 3 {
		score += 15
	}
	if replies > 0 && likes > 0 && replies*3 >= likes {
		score += 10
	}
	if score > 100 {
		return 100
	}
	return score
}

func PriorityLabel(score int) string {
	if score >= HotEngagementScore {
		return "hot"
	}
	if score >= MinEngagementScore {
		return "warm"
	}
	return "cold"
}

func PassesViralCandidate(text string, likes, replies, engagementScore int, exclusions []string) bool {
	if strings.TrimSpace(text) == "" {
		return false
	}
	if placement.MatchesExclusion(text, exclusions) {
		return false
	}
	if placement.LooksLikeCasualChat(text) && !hasViralSignal(text) {
		return false
	}
	if likes < MinLikeCount && engagementScore < MinEngagementScore {
		return false
	}
	if engagementScore < MinEngagementScore {
		return false
	}
	return true
}

func hasViralSignal(text string) bool {
	text = strings.ToLower(text)
	signals := []string{"分享", "推薦", "心得", "技巧", "方法", "語錄", "故事", "怎麼", "為什麼", "必看"}
	for _, s := range signals {
		if strings.Contains(text, s) {
			return true
		}
	}
	return len([]rune(text)) >= 40
}