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//go:build !chunkdemo

package main

import (
	"fmt"
	"math"
	"os"
	"time"
)

// main is omitted under -tags chunkdemo, where chunkdemo.go provides its own.
// Everything below this point (the embedder, the downloader) is shared by both.
func main() {
	if err := run(); err != nil {
		fmt.Fprintf(os.Stderr, "fedisearch-spike: %v\n", err)
		os.Exit(1)
	}
}

func run() error {
	modelDir, err := ensureModel()
	if err != nil {
		return fmt.Errorf("obtaining model: %w", err)
	}

	emb, err := newEmbedder(modelDir)
	if err != nil {
		return fmt.Errorf("loading model: %w", err)
	}
	defer emb.close()

	fmt.Printf("model inputs:  %v\n", emb.inputNames)
	fmt.Printf("model outputs: %v\n", emb.outputNames)

	const text = "robert smith"
	start := time.Now()
	vec, err := emb.embed(text)
	if err != nil {
		return fmt.Errorf("embedding %q: %w", text, err)
	}
	elapsed := time.Since(start)

	fmt.Printf("\nembedding of %q: %d dims in %s\n", text, len(vec), elapsed.Round(time.Millisecond))
	fmt.Printf("first 8: %v\n", vec[:8])
	fmt.Printf("L2 norm: %.5f\n", l2Norm(vec))

	if err := checkAgainstReference(vec); err != nil {
		return err
	}
	fmt.Printf("\nOK: matches reference vector within %g\n", tolerance)
	return nil
}

// checkAgainstReference compares the computed embedding against the known-good
// vector, reporting the worst offender rather than just the first mismatch, so
// a systematic error is easier to recognise than a one-off.
func checkAgainstReference(got []float32) error {
	if len(got) != 384 {
		return fmt.Errorf("expected 384 dimensions, got %d", len(got))
	}
	worstIdx, worstDiff := -1, 0.0
	for i, want := range expectedRobertSmith {
		diff := math.Abs(float64(got[i] - want))
		if diff > worstDiff {
			worstIdx, worstDiff = i, diff
		}
	}
	if worstDiff > tolerance {
		return fmt.Errorf(
			"embedding does not match reference: worst mismatch at dim %d: got %v, want %v (diff %g > %g)",
			worstIdx, got[worstIdx], expectedRobertSmith[worstIdx], worstDiff, tolerance)
	}
	return nil
}

func l2Norm(v []float32) float64 {
	var sum float64
	for _, x := range v {
		sum += float64(x) * float64(x)
	}
	return math.Sqrt(sum)
}