package embed

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"testing"
)

func TestOllama_EmbedBatch_PreservesOrder(t *testing.T) {
	var mu sync.Mutex
	var seenPrompts []string
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var req ollamaRequest
		_ = json.NewDecoder(r.Body).Decode(&req)
		mu.Lock()
		seenPrompts = append(seenPrompts, req.Prompt)
		mu.Unlock()
		// Return a vector that encodes which prompt this was, so
		// we can assert order at the caller. 4-d vector for cheap.
		var vec [4]float64
		switch req.Prompt {
		case "alpha":
			vec = [4]float64{1, 0, 0, 0}
		case "beta":
			vec = [4]float64{0, 1, 0, 0}
		case "gamma":
			vec = [4]float64{0, 0, 1, 0}
		}
		_ = json.NewEncoder(w).Encode(map[string]any{"embedding": vec[:]})
	}))
	defer srv.Close()

	p := NewOllama(srv.URL, "test-model")
	res, err := p.Embed(context.Background(), []string{"alpha", "beta", "gamma"}, "")
	if err != nil {
		t.Fatal(err)
	}
	if res.Model != "test-model" || res.Dimension != 4 || len(res.Vectors) != 3 {
		t.Fatalf("Result: got %+v", res)
	}
	if res.Vectors[0][0] != 1 || res.Vectors[1][1] != 1 || res.Vectors[2][2] != 1 {
		t.Errorf("vectors out of order: %v", res.Vectors)
	}
	// Sanity: all three prompts hit the server.
	if len(seenPrompts) != 3 {
		t.Errorf("expected 3 upstream calls, got %d", len(seenPrompts))
	}
}

func TestOllama_EmptyTextsErrors(t *testing.T) {
	p := NewOllama("http://nope:0", "x")
	_, err := p.Embed(context.Background(), nil, "")
	if !errors.Is(err, ErrEmptyTexts) {
		t.Errorf("expected ErrEmptyTexts, got %v", err)
	}
}

func TestOllama_NoModelNoDefault(t *testing.T) {
	p := NewOllama("http://nope:0", "") // empty default
	_, err := p.Embed(context.Background(), []string{"hi"}, "")
	if err == nil || !strings.Contains(err.Error(), "no model") {
		t.Errorf("expected no-model error, got %v", err)
	}
}

func TestOllama_UpstreamErrorPropagates(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		http.Error(w, "model not loaded", http.StatusInternalServerError)
	}))
	defer srv.Close()
	p := NewOllama(srv.URL, "x")
	_, err := p.Embed(context.Background(), []string{"hi"}, "")
	if err == nil || !strings.Contains(err.Error(), "upstream status 500") {
		t.Errorf("expected wrapped 500 error, got %v", err)
	}
}

func TestOllama_DimensionMismatchMidBatch(t *testing.T) {
	calls := 0
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		calls++
		// First call returns 4-d, second returns 8-d → server changed
		// model under us. Provider should ErrModelMismatch.
		var v []float64
		if calls == 1 {
			v = []float64{1, 0, 0, 0}
		} else {
			v = []float64{1, 0, 0, 0, 0, 0, 0, 0}
		}
		_ = json.NewEncoder(w).Encode(map[string]any{"embedding": v})
	}))
	defer srv.Close()
	p := NewOllama(srv.URL, "x")
	_, err := p.Embed(context.Background(), []string{"a", "b"}, "")
	if !errors.Is(err, ErrModelMismatch) {
		t.Errorf("expected ErrModelMismatch, got %v", err)
	}
}

func TestOllama_EmptyEmbeddingErrors(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		_ = json.NewEncoder(w).Encode(map[string]any{"embedding": []float64{}})
	}))
	defer srv.Close()
	p := NewOllama(srv.URL, "x")
	_, err := p.Embed(context.Background(), []string{"hi"}, "")
	if err == nil || !strings.Contains(err.Error(), "empty embedding") {
		t.Errorf("expected empty-embedding error, got %v", err)
	}
}
