package index

import (
	"searchEngine/core/analyzer"
	"sync"
)

type Posting struct {
	DocId          int
	BodyCount      int
	TitleCount     int
	BodyPositions  []int
	TitlePositions []int
}

type InvertedIndex struct {
	Mu       sync.RWMutex
	Data     map[string][]Posting
	DocNames map[int]string
}

func New() *InvertedIndex {
	return &InvertedIndex{
		Data:     make(map[string][]Posting),
		DocNames: make(map[int]string),
	}
}

func (idx *InvertedIndex) Add(docID int, title string, bodyTokens []string) {
	titleTokens := analyzer.ProcessText(title)

	type fieldStats struct {
		body           int
		bodyPositions  []int
		title          int
		titlePositions []int
	}
	docStats := make(map[string]fieldStats)

	for position, token := range titleTokens {
		stats := docStats[token]
		stats.title++
		stats.titlePositions = append(stats.titlePositions, position)
		docStats[token] = stats
	}

	for position, token := range bodyTokens {
		stats := docStats[token]
		stats.body++
		stats.bodyPositions = append(stats.bodyPositions, position)
		docStats[token] = stats
	}

	idx.Mu.Lock()
	defer idx.Mu.Unlock()

	idx.DocNames[docID] = title

	for token, stats := range docStats {
		idx.Data[token] = append(idx.Data[token], Posting{
			DocId:          docID,
			BodyCount:      stats.body,
			TitleCount:     stats.title,
			BodyPositions:  stats.bodyPositions,
			TitlePositions: stats.titlePositions,
		})
	}
}