package indexDB

import (
	"context"
	"fmt"
	"path/filepath"
	"runtime"

	"github.com/philippgille/chromem-go"

	"apigo.cc/go/cast"
)

type Store struct {
	db *chromem.DB
}

type Config struct {
	StorageDir string 
}

func newVectorStore(cfg Config) (*Store, error) {
	var db *chromem.DB
	var err error

	if cfg.StorageDir == "" {
		db = chromem.NewDB()
	} else {
		path := filepath.Clean(cfg.StorageDir)
		db, err = chromem.NewPersistentDB(path, false)
		if err != nil {
			return nil, fmt.Errorf("failed to open persistent vector DB: %w", err)
		}
	}

	return &Store{db: db}, nil
}

type Collection struct {
	coll *chromem.Collection
}

func (s *Store) GetOrCreateCollection(name string) (*Collection, error) {
	coll := s.db.GetCollection(name, nil)
	if coll == nil {
		var err error
		coll, err = s.db.CreateCollection(name, nil, nil)
		if err != nil {
			return nil, fmt.Errorf("failed to create collection: %w", err)
		}
	}
	return &Collection{coll: coll}, nil
}

func (c *Collection) AddRecord(id string, vector []float32, metadata map[string]any, allowUsers []string) error {
	rawJson := cast.As(cast.ToJSON(metadata))
	metaStr := map[string]string{
		"raw_json": rawJson,
	}
	for _, u := range allowUsers {
		metaStr["U-"+u] = "1"
	}

	doc := chromem.Document{
		ID:        id,
		Embedding: vector,
		Metadata:  metaStr,
	}

	err := c.coll.AddDocuments(context.Background(), []chromem.Document{doc}, runtime.NumCPU())
	if err != nil {
		return fmt.Errorf("failed to add records: %w", err)
	}
	return nil
}

func (c *Collection) Search(queryVector []float32, topK int, userID string, idPrefix string, filter []Condition) ([]SearchResult, error) {
	var vFilter map[string]string
	if userID != "" && userID != SystemUserID {
		vFilter = map[string]string{
			"U-" + userID: "1",
		}
	}

	count := c.coll.Count()
	if count == 0 {
		return nil, nil
	}

	nResults := topK * 10
	if len(filter) > 0 || idPrefix != "" {
		// If there are filters, we should fetch as much as possible to ensure accuracy.
		nResults = count
	}

	if nResults > count {
		nResults = count
	}

	// We query more and filter in memory since Chromem-go only supports exact map filter.
	res, err := c.coll.QueryEmbedding(context.Background(), queryVector, nResults, vFilter, nil)
	if err != nil {
		return nil, fmt.Errorf("vector search failed: %w", err)
	}

	var results []SearchResult
	for _, r := range res {
		var metaIfc map[string]any
		if raw, ok := r.Metadata["raw_json"]; ok {
			metaIfc = cast.As(cast.FromJSON[map[string]any](raw))
		} else {
			metaIfc = make(map[string]any)
		}

		if !evalCondition(metaIfc, r.ID, idPrefix, filter) {
			continue
		}

		results = append(results, SearchResult{
			ID:       r.ID,
			Score:    r.Similarity,
			Content:  r.Content,
			Metadata: metaIfc,
		})

		if len(results) >= topK {
			break
		}
	}

	return results, nil
}

func (c *Collection) DeleteRecord(id string) error {
	return c.coll.Delete(context.Background(), nil, nil, id)
}