package snippet

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"regexp"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/qdrant/go-client/qdrant"
)

func Main() {
	// @block-start client-connection
	// Replace the host and API key with your own from https://cloud.qdrant.io
	client, err := qdrant.NewClient(&qdrant.Config{
		Host:   "xyz-example.qdrant.io",
		APIKey: "<your-api-key>",
		UseTLS: true,
	})
	// @block-end client-connection

	// @hide-start
	if err != nil {
		panic(err)
	}

	// data and text normalization are not the lesson of this tutorial:
	// the full CHUNKS list and normalize() live in the tutorial notebook
	type Chunk struct {
		URL         string
		Anchor      string
		ChunkNum    int
		Text        string
		SectionURL  string
		ContentHash string
		PointID     string
	}

	CHUNKS := []Chunk{
		{
			URL:      "https://qdrant.tech/documentation/tutorials-operations/secure-qdrant/",
			Anchor:   "prerequisites",
			ChunkNum: 0,
			Text:     "Prerequisites - Docker and Docker Compose installed - `curl` available in your terminal ...",
		},
		{
			URL:      "https://qdrant.tech/documentation/tutorials-operations/secure-qdrant/",
			Anchor:   "step-3-enable-an-admin-api-key",
			ChunkNum: 0,
			Text:     "Step 3: Enable an Admin API Key Without enabling authentication, anyone with network access ...",
		},
	}

	invisibleChars := regexp.MustCompile("[\u200B\u200C\u200D\uFEFF\u00AD]") // zero-width chars and soft hyphen
	whitespace := regexp.MustCompile(`\s+`)
	normalize := func(text string) string {
		text = invisibleChars.ReplaceAllString(text, "")
		return strings.TrimSpace(whitespace.ReplaceAllString(text, " "))
	}
	// @hide-end

	// @block-start create-collection
	MODEL := "sentence-transformers/all-MiniLM-L6-v2"
	PIPELINE := "docs-prep-pipeline-v1"
	COLLECTION := "docs-sync-tutorial"

	client.CreateCollection(context.Background(), &qdrant.CreateCollection{
		CollectionName: COLLECTION,
		VectorsConfig: qdrant.NewVectorsConfig(&qdrant.VectorParams{
			Size:     384, // all-MiniLM-L6-v2 output dimension
			Distance: qdrant.Distance_Cosine,
		}),
		Metadata: qdrant.NewValueMap(map[string]any{
			"embedding_model":  MODEL,
			"pipeline_version": PIPELINE,
		}),
	})
	// @block-end create-collection

	// @block-start check-gate
	checkGate := func() {
		// compare this pipeline's constants against what the collection records about itself
		info, err := client.GetCollectionInfo(context.Background(), COLLECTION)
		if err != nil { panic(err) } // @hide
		meta := info.GetConfig().GetMetadata()

		if meta["embedding_model"].GetStringValue() != MODEL || meta["pipeline_version"].GetStringValue() != PIPELINE {
			panic(fmt.Sprintf("collection was built by %v: full re-embed into a fresh collection required", meta))
		}
	}
	// @block-end check-gate

	// @block-start identity-and-fingerprint
	contentHash := func(text string) string {
		sum := sha256.Sum256([]byte(text))
		return hex.EncodeToString(sum[:])
	}

	pointID := func(url, anchor string, num int) string {
		// NewSHA1 with a namespace is UUIDv5; NameSpaceURL is a fixed constant it requires,
		// marking the input as a URL-like name
		return uuid.NewSHA1(uuid.NameSpaceURL, []byte(fmt.Sprintf("%s#%s::%d", url, anchor, num))).String()
	}

	// derive both values (and the section address) for every raw chunk
	prepareChunksForSync := func(chunks []Chunk) []Chunk {
		out := make([]Chunk, 0, len(chunks))
		for _, c := range chunks {
			c.Text = normalize(c.Text)
			c.SectionURL = c.URL
			if c.Anchor != "" {
				c.SectionURL = c.URL + "#" + c.Anchor
			}
			c.ContentHash = contentHash(c.Text)
			c.PointID = pointID(c.URL, c.Anchor, c.ChunkNum)
			out = append(out, c)
		}
		return out
	}
	// @block-end identity-and-fingerprint

	// @block-start payload
	payload := func(c Chunk, lastUpdated string) map[string]any {
		if lastUpdated == "" {
			lastUpdated = time.Now().UTC().Format(time.RFC3339)
		}
		return map[string]any{
			"url":          c.URL,
			"anchor":       c.Anchor,
			"chunk_num":    c.ChunkNum,
			"section_url":  c.SectionURL,
			"text":         c.Text,
			"content_hash": c.ContentHash,
			"last_updated": lastUpdated,
		}
	}
	// @block-end payload

	// @block-start payload-indexes
	for _, field := range []string{"content_hash", "url", "section_url"} {
		client.CreateFieldIndex(context.Background(), &qdrant.CreateFieldIndexCollection{
			CollectionName: COLLECTION,
			FieldName:      field,
			FieldType:      qdrant.FieldType_FieldTypeKeyword.Enum(),
		})
	}
	// @block-end payload-indexes

	// @block-start populate
	var points []*qdrant.PointStruct
	for _, c := range prepareChunksForSync(CHUNKS) {
		points = append(points, &qdrant.PointStruct{
			Id: qdrant.NewID(c.PointID),

			Vectors: qdrant.NewVectorsDocument(&qdrant.Document{Text: c.Text, Model: MODEL}),
			Payload: qdrant.NewValueMap(payload(c, "")),
		})
	}
	client.Upsert(context.Background(), &qdrant.UpsertPoints{
		CollectionName: COLLECTION,
		Points:         points,
		Wait:           qdrant.PtrOf(true),
	})
	// @block-end populate

	// @block-start search
	QUERY := "Where exactly to set `QDRANT__SERVICE__API_KEY` variable to enable authentication for a self-hosted Qdrant?"

	client.Query(context.Background(), &qdrant.QueryPoints{
		CollectionName: COLLECTION,
		Query:          qdrant.NewQueryDocument(&qdrant.Document{Text: QUERY, Model: MODEL}),
		Limit:          qdrant.PtrOf(uint64(3)),
		WithPayload:    qdrant.NewWithPayloadInclude("section_url", "text"),
	})
	// @block-end search

	// @hide-start
	// the simulated month of edits (LATEST_CHUNKS) is spelled out in the tutorial and the notebook
	LATEST_CHUNKS := prepareChunksForSync(CHUNKS)
	// @hide-end

	// @block-start split-by-state
	// compare the incoming chunk list to the collection: who is unchanged, changed, or unknown
	splitByState := func(latestChunks []Chunk) (map[string]Chunk, []Chunk, []Chunk, []Chunk) {
		incoming := make(map[string]Chunk, len(latestChunks))
		ids := make([]*qdrant.PointId, 0, len(latestChunks))
		for _, c := range latestChunks {
			incoming[c.PointID] = c
			ids = append(ids, qdrant.NewID(c.PointID))
		}

		retrieved, err := client.Get(context.Background(), &qdrant.GetPoints{
			CollectionName: COLLECTION,
			Ids:            ids,
			WithPayload:    qdrant.NewWithPayloadInclude("content_hash"),
			WithVectors:    qdrant.NewWithVectors(false),
		})
		if err != nil { panic(err) } // @hide
		stored := make(map[string]string, len(retrieved))
		for _, p := range retrieved {
			stored[p.GetId().GetUuid()] = p.GetPayload()["content_hash"].GetStringValue()
		}

		var unchanged, contentChanged, unknownIDs []Chunk
		for pid, c := range incoming {
			storedHash, found := stored[pid]
			switch {
			case found && storedHash == c.ContentHash:
				unchanged = append(unchanged, c)
			case found:
				contentChanged = append(contentChanged, c)
			default:
				unknownIDs = append(unknownIDs, c)
			}
		}

		return incoming, unchanged, contentChanged, unknownIDs
	}

	incomingIDs, unchanged, contentChanged, unknownIDs := splitByState(LATEST_CHUNKS)
	// @block-end split-by-state

	// @hide-start
	_, _, _, _ = incomingIDs, unchanged, contentChanged, unknownIDs
	// @hide-end

	// @block-start re-embed-changed
	reEmbedChanged := func(contentChanged []Chunk) {
		if len(contentChanged) == 0 {
			return
		}
		points := make([]*qdrant.PointStruct, 0, len(contentChanged))
		for _, c := range contentChanged {
			points = append(points, &qdrant.PointStruct{
				Id:      qdrant.NewID(c.PointID),
				Vectors: qdrant.NewVectorsDocument(&qdrant.Document{Text: c.Text, Model: MODEL}),
				Payload: qdrant.NewValueMap(payload(c, "")),
			})
		}
		client.Upsert(context.Background(), &qdrant.UpsertPoints{
			CollectionName: COLLECTION,
			Points:         points,
			Wait:           qdrant.PtrOf(true),
		})
	}
	// @block-end re-embed-changed

	// @block-start reuse-or-add
	// reuse an existing embedding when the same text is already stored; embed only what is new
	reuseOrAdd := func(unknownIDs []Chunk) (int, int) {
		reused, added := 0, 0

		for _, c := range unknownIDs {
			sameText := &qdrant.Filter{
				Must: []*qdrant.Condition{
					qdrant.NewMatch("content_hash", c.ContentHash),
				},
			}
			hits, err := client.Scroll(context.Background(), &qdrant.ScrollPoints{
				CollectionName: COLLECTION,
				Filter:         sameText,
				Limit:          qdrant.PtrOf(uint32(1)),
				WithPayload:    qdrant.NewWithPayloadInclude("last_updated"),
				WithVectors:    qdrant.NewWithVectors(true),
			})
			if err != nil { panic(err) } // @hide

			var point *qdrant.PointStruct
			if len(hits) > 0 { // same text, new address: copy the vector, keep its last_updated
				point = &qdrant.PointStruct{
					Id:      qdrant.NewID(c.PointID),
					Vectors: qdrant.NewVectors(hits[0].GetVectors().GetVector().GetData()...),
					Payload: qdrant.NewValueMap(payload(c, hits[0].GetPayload()["last_updated"].GetStringValue())),
				}
				reused++
			} else { // genuinely new content: embed and insert
				point = &qdrant.PointStruct{
					Id:      qdrant.NewID(c.PointID),
					Vectors: qdrant.NewVectorsDocument(&qdrant.Document{Text: c.Text, Model: MODEL}),
					Payload: qdrant.NewValueMap(payload(c, "")),
				}
				added++
			}

			client.Upsert(context.Background(), &qdrant.UpsertPoints{
				CollectionName: COLLECTION,
				Points:         []*qdrant.PointStruct{point},
				Wait:           qdrant.PtrOf(true),
			})
		}

		return reused, added
	}
	// @block-end reuse-or-add

	// @block-start delete-gone
	// remove every point the current crawl no longer contains, return how many
	deleteGone := func(incomingIDs map[string]Chunk) int {
		if len(incomingIDs) == 0 {
			panic("Refusing to delete from an empty source snapshot.")
		}

		ids := make([]*qdrant.PointId, 0, len(incomingIDs))
		for pid := range incomingIDs {
			ids = append(ids, qdrant.NewID(pid))
		}
		stale := &qdrant.Filter{
			MustNot: []*qdrant.Condition{qdrant.NewHasID(ids...)},
		}

		toDelete, err := client.Count(context.Background(), &qdrant.CountPoints{
			CollectionName: COLLECTION,
			Filter:         stale,
		})
		if err != nil { panic(err) } // @hide

		// potential check against a threshold to avoid accidental mass deletion could be added here
		client.Delete(context.Background(), &qdrant.DeletePoints{
			CollectionName: COLLECTION,
			Points:         qdrant.NewPointsSelectorFilter(stale),
			Wait:           qdrant.PtrOf(true),
		})
		return int(toDelete)
	}
	// @block-end delete-gone

	// @block-start sync
	sync := func(latestChunks []Chunk) map[string]int {
		checkGate() // refuse to mix embedding models or pipeline versions

		chunks := prepareChunksForSync(latestChunks)
		incomingIDs, unchanged, contentChanged, unknownIDs := splitByState(chunks)

		reEmbedChanged(contentChanged)
		reused, added := reuseOrAdd(unknownIDs)
		deleted := deleteGone(incomingIDs)

		return map[string]int{
			"unchanged":        len(unchanged),
			"re-embedded":      len(contentChanged),
			"reused_embedding": reused,
			"added":            added,
			"deleted":          deleted,
		}
	}
	// @block-end sync

	// @block-start run-sync
	run := sync(LATEST_CHUNKS)
	fmt.Println(run)
	// @block-end run-sync
}