package services

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"nearle/models"
)

/*
The health score on the product screen.

Most of this file is about what the score REFUSES to say. The number itself is
the service's; the judgements around it — which band, whether the match is sure
enough to state plainly, whether the product is even food — are decisions this
code makes on a shopper's behalf, and each one has a way of being wrong that
matters more than being absent.

The fixture is the service's own record for Balaji Wafers Simply Salted, read
from mcp.nearle.ai.in on 29 Sep 2026: a real score of 65.3 on a real product in
a real tenant's catalogue, matched at 0.607 confidence — below the line.
*/
const balajiJSON = `{
  "data_status": "verified", "category": "Snacks",
  "health_score": 65.3, "nutrition_score": 61.0, "match_confidence": 0.607,
  "positive_insights": ["Good source of fibre (9.3 g per 100 g)."],
  "nutritional_cautions": ["High in saturated fat (14.4 g per 100 g)."],
  "diet_tags": ["Vegetarian"], "allergens": [],
  "data_source": "openfoodfacts", "source_url": "https://world.openfoodfacts.org/product/1",
  "calories_kcal": 545, "protein_g": 7.5, "total_fat_g": 30.7
}`

func healthOf(t *testing.T, raw string) *models.HealthScore {
	t.Helper()
	var source NutritionSource
	if err := json.Unmarshal([]byte(raw), &source); err != nil {
		t.Fatalf("fixture: %v", err)
	}
	return source.Health()
}

func TestARealScoreReachesTheApp(t *testing.T) {
	score := healthOf(t, balajiJSON)
	if score == nil {
		t.Fatal("no score from a verified, edible, scored product")
	}
	if score.Score != 65 {
		// Rounded: the service sends 65.3 and nobody reads the decimal.
		t.Errorf("score = %d, want 65", score.Score)
	}
	if score.Band != "good" || score.Label != "Healthy" {
		t.Errorf("band = %q / %q", score.Band, score.Label)
	}
	if len(score.Positives) != 1 || len(score.Cautions) != 1 {
		t.Errorf("insights lost: %+v / %+v", score.Positives, score.Cautions)
	}
	if score.Source == nil || score.Source.Label != "openfoodfacts" {
		t.Errorf("source lost: %+v", score.Source)
	}
}

/* ── What it refuses to say ──────────────────────────────────────────────── */

func TestSomethingThatIsNotFoodGetsNoScore(t *testing.T) {
	// The reason this guard exists. Measured 4 Sep 2026, the upstream
	// per-product endpoint rated Godrej Hit insecticide 80/100 with
	// data_status "verified"; soap and shampoo both scored 37.5 the same way.
	// Those records now read "unavailable", and the guard stays: this tenant
	// sells soap and toothpaste next to its biscuits.
	for _, category := range []string{"Household", "Personal Care", "Insecticide", "Cosmetics"} {
		raw := strings.Replace(balajiJSON, `"category": "Snacks"`, `"category": "`+category+`"`, 1)
		if score := healthOf(t, raw); score != nil {
			t.Errorf("%s was rated %d/100", category, score.Score)
		}
	}
}

func TestAnUnknownCategoryIsTreatedAsNotFood(t *testing.T) {
	// An allowlist, because the two failure modes are not symmetric. Withholding
	// a badge from real food costs a shopper something they never had; putting
	// one on bleach is a different order of mistake.
	for _, category := range []string{`null`, `""`, `"General"`, `"Miscellaneous"`} {
		raw := strings.Replace(balajiJSON, `"category": "Snacks"`, `"category": `+category, 1)
		if score := healthOf(t, raw); score != nil {
			t.Errorf("category %s was scored %d/100", category, score.Score)
		}
	}
}

func TestAnUnscoredProductGetsNoScore(t *testing.T) {
	// The common case: the service knows the product and has not rated it.
	raw := strings.Replace(balajiJSON, `"health_score": 65.3`, `"health_score": null`, 1)
	if score := healthOf(t, raw); score != nil {
		t.Fatalf("invented a score: %+v", score)
	}
}

/* ── Saying how sure it is ───────────────────────────────────────────────── */

func TestAWeakMatchIsDeclared(t *testing.T) {
	// 0.607 is below the 0.7 line. A nutrition table presented as fact on a 61%
	// match is a claim the data does not support.
	score := healthOf(t, balajiJSON)
	if score.Caveat == "" {
		t.Fatal("a 0.607 match was presented as fact")
	}
	if !strings.Contains(score.Caveat, "61%") {
		t.Errorf("the caveat does not say how sure: %q", score.Caveat)
	}
}

func TestAStrongMatchNeedsNoApology(t *testing.T) {
	raw := strings.Replace(balajiJSON, `"match_confidence": 0.607`, `"match_confidence": 0.94`, 1)
	if score := healthOf(t, raw); score.Caveat != "" {
		t.Errorf("apologised for a 94%% match: %q", score.Caveat)
	}
}

func TestAnEmptyAllergenListOnAWeakMatchIsFlagged(t *testing.T) {
	// The one that could actually hurt somebody. The service matches sources
	// down to 0.32 confidence, and "verified" speaks to the numbers being real,
	// not to the record being THIS product. Silence must not stand in for
	// "contains none" — the app has to say "not confirmed" rather than draw
	// nothing.
	score := healthOf(t, balajiJSON)
	if !score.Allergensunconfirmed {
		t.Fatal("an empty allergen list on a 61% match was left to speak for itself")
	}
}

func TestADeclaredAllergenIsAlwaysShown(t *testing.T) {
	// A false positive sends somebody to read the packet. A false negative sends
	// them to hospital. So a declared allergen survives a weak match.
	raw := strings.Replace(balajiJSON, `"allergens": []`, `"allergens": ["Milk", "Soy"]`, 1)
	score := healthOf(t, raw)
	if len(score.Allergens) != 2 {
		t.Fatalf("a declared allergen was dropped: %+v", score.Allergens)
	}
	if score.Allergensunconfirmed {
		t.Error("a list with entries in it was flagged as unconfirmed")
	}
}

func TestAnEmptyListOnAStrongMatchIsNotFlagged(t *testing.T) {
	raw := strings.Replace(balajiJSON, `"match_confidence": 0.607`, `"match_confidence": 0.94`, 1)
	if healthOf(t, raw).Allergensunconfirmed {
		t.Error("flagged an empty list that the match actually supports")
	}
}

/* ── Bands ───────────────────────────────────────────────────────────────── */

func TestTheBandThresholdsAreTheServices(t *testing.T) {
	// Confirmed by that team in writing. The per-product endpoint sends no
	// band, so these are the only path — picking our own would be one API
	// disagreeing with itself depending which endpoint a screen called.
	for _, tc := range []struct {
		score float64
		band  string
		label string
	}{
		{92, "excellent", "Very healthy"},
		{80, "excellent", "Very healthy"},
		{79.9, "good", "Healthy"},
		{60, "good", "Healthy"},
		{59.9, "fair", "Okay"},
		{40, "fair", "Okay"},
		{39.9, "poor", "Less healthy"},
		{0, "poor", "Less healthy"},
	} {
		band := models.BandFor(tc.score, "")
		if band != tc.band || models.BandLabel(band) != tc.label {
			t.Errorf("%v → %q/%q, want %q/%q",
				tc.score, band, models.BandLabel(band), tc.band, tc.label)
		}
	}
}

func TestTheServicesOwnBandWinsWhenItSendsOne(t *testing.T) {
	// It does not today, from this endpoint. When it starts, its answer is the
	// authority and the thresholds above become the fallback they were meant to
	// be.
	if got := models.BandFor(20, "excellent"); got != "excellent" {
		t.Errorf("ignored the service's own band: %q", got)
	}
	if got := models.BandFor(20, "  GOOD  "); got != "good" {
		t.Errorf("did not normalise the service's band: %q", got)
	}
	if got := models.BandFor(85, "nonsense"); got != "excellent" {
		t.Errorf("trusted a band it does not recognise: %q", got)
	}
}

/* ── On the wire ─────────────────────────────────────────────────────────── */

func TestTheScoreAndThePanelAreIndependent(t *testing.T) {
	// A product can be scored with no figures published, and carry figures with
	// no score. Tying them together would blank one because the other was
	// missing.
	noFigures := `{"category":"Snacks","health_score":65.3,"match_confidence":0.9}`
	var source NutritionSource
	if err := json.Unmarshal([]byte(noFigures), &source); err != nil {
		t.Fatalf("fixture: %v", err)
	}
	if source.Panel() != nil {
		t.Error("made a panel with no figures")
	}
	if source.Health() == nil {
		t.Error("withheld a score because there were no figures")
	}
}

func TestBothHalvesComeFromOneRequest(t *testing.T) {
	// Splitting a record the service returns whole would double the traffic to
	// a third party on a screen a shopper is waiting on.
	var hits int
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path == "/brands" {
			_, _ = w.Write([]byte(`{"brands":["Balaji"]}`))
			return
		}
		hits++
		_, _ = w.Write([]byte(balajiJSON))
	}))
	defer server.Close()

	found := NewNutritionService(server.URL).ForProduct("balaji", "balaji_wafers_135g")
	if hits != 1 {
		t.Fatalf("made %d requests for one product", hits)
	}
	if !found.Panel.HasValues() || found.Health == nil {
		t.Fatal("one of the two halves was lost")
	}
}

func TestTheWireNamesForTheScore(t *testing.T) {
	row := models.Products{Productid: 7101}
	row.Healthscore = healthOf(t, balajiJSON)

	encoded, err := json.Marshal(row)
	if err != nil {
		t.Fatalf("marshal: %v", err)
	}
	var out map[string]any
	if err := json.Unmarshal(encoded, &out); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}

	health, ok := out["healthscore"].(map[string]any)
	if !ok {
		t.Fatalf("no `healthscore` key: %s", encoded)
	}
	for _, key := range []string{"score", "band", "label", "caveat", "allergensunconfirmed"} {
		if _, ok := health[key]; !ok {
			t.Errorf("missing %q: %v", key, health)
		}
	}
}

func TestAProductWithNoScoreHasNoKeyAtAll(t *testing.T) {
	// Not `"healthscore": null`. Most products have none.
	encoded, _ := json.Marshal(models.Products{Productid: 1})
	var out map[string]any
	_ = json.Unmarshal(encoded, &out)
	if _, present := out["healthscore"]; present {
		t.Fatalf("an absent score was sent as a key: %s", encoded)
	}
}

func TestSoapOnTheProductScreenCarriesNoScore(t *testing.T) {
	// End to end, through the decoration the endpoint actually calls. This is
	// the failure a shopper would see: a health rating on a bar of soap.
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path == "/brands" {
			_, _ = w.Write([]byte(`{"brands":["Godrej"]}`))
			return
		}
		_, _ = w.Write([]byte(strings.Replace(balajiJSON,
			`"category": "Snacks"`, `"category": "Personal Care"`, 1)))
	}))
	defer server.Close()

	rows := []models.Products{{Productid: 7121, Productbrand: "godrej", Imageid: "godrej_soap_100g"}}
	decorateNutrition(NewNutritionService(server.URL), rows)

	if rows[0].Healthscore != nil {
		t.Fatalf("a bar of soap was rated %d/100", rows[0].Healthscore.Score)
	}
}