package matrix

import "strings"

// SelectKnowledgeItems prefers explicit selections, otherwise falls back to all items.
func SelectKnowledgeItems(selected, all []string) []string {
	source := selected
	if len(source) == 0 {
		source = all
	}
	return dedupeKnowledgeLines(source)
}

// MergeKnowledgeItems combines explicit user selections without falling back to unselected items.
func MergeKnowledgeItems(parts ...[]string) []string {
	merged := make([]string, 0)
	for _, part := range parts {
		merged = append(merged, part...)
	}
	return dedupeKnowledgeLines(merged)
}

func dedupeKnowledgeLines(lines []string) []string {
	out := make([]string, 0, len(lines))
	seen := map[string]struct{}{}
	for _, item := range lines {
		item = strings.TrimSpace(item)
		if item == "" {
			continue
		}
		key := strings.ToLower(item)
		if _, ok := seen[key]; ok {
			continue
		}
		seen[key] = struct{}{}
		out = append(out, item)
	}
	return out
}

// FormatCopyResearchMapBlock renders a compact research-map block for LLM prompts.
func FormatCopyResearchMapBlock(audience, goal string, questions, pillars, exclusions []string, knowledgeItems ...[]string) string {
	var b strings.Builder
	if audience = strings.TrimSpace(audience); audience != "" {
		b.WriteString("受眾：")
		b.WriteString(audience)
		b.WriteString("\n")
	}
	if goal = strings.TrimSpace(goal); goal != "" {
		b.WriteString("內容目標：")
		b.WriteString(goal)
		b.WriteString("\n")
	}
	if len(pillars) > 0 {
		b.WriteString("支柱：")
		b.WriteString(strings.Join(pillars, "、"))
		b.WriteString("\n")
	}
	if len(questions) > 0 {
		b.WriteString("受眾問題：")
		b.WriteString(strings.Join(questions, "；"))
		b.WriteString("\n")
	}
	if len(knowledgeItems) > 0 && len(knowledgeItems[0]) > 0 {
		b.WriteString("勾選延伸知識：")
		b.WriteString(strings.Join(knowledgeItems[0], "；"))
		b.WriteString("\n")
	}
	if len(exclusions) > 0 {
		b.WriteString("排除：")
		b.WriteString(strings.Join(exclusions, "；"))
	}
	return strings.TrimSpace(b.String())
}