package api

import (
	"testing"

	"github.com/ponzischeme89/memby/server/internal/store"
)

func TestNormaliseGenreAffinityScalesToTheTopGenre(t *testing.T) {
	response := normaliseGenreAffinity(store.GenreAffinity{
		Sessions: 40,
		Genres: []store.GenreWeight{
			{Genre: "Crime", Score: 20},
			{Genre: "Drama", Score: 10},
			{Genre: "Western", Score: 1},
		},
	})
	if response.Sessions != 40 {
		t.Fatalf("sessions = %d, want 40", response.Sessions)
	}
	if len(response.Genres) != 3 {
		t.Fatalf("genres = %d, want 3", len(response.Genres))
	}
	if response.Genres[0].Genre != "Crime" || response.Genres[0].Weight != 1 {
		t.Fatalf("top = %+v, want Crime at 1", response.Genres[0])
	}
	if response.Genres[1].Weight != 0.5 {
		t.Fatalf("Drama = %v, want 0.5", response.Genres[1].Weight)
	}
}

// A share is the whole point: two households with wildly different amounts of viewing must
// produce the same ordering from the same balance of it.
func TestNormaliseGenreAffinityIsScaleFree(t *testing.T) {
	light := normaliseGenreAffinity(store.GenreAffinity{Sessions: 12, Genres: []store.GenreWeight{
		{Genre: "Comedy", Score: 3}, {Genre: "Horror", Score: 1},
	}})
	heavy := normaliseGenreAffinity(store.GenreAffinity{Sessions: 900, Genres: []store.GenreWeight{
		{Genre: "Comedy", Score: 300}, {Genre: "Horror", Score: 100},
	}})
	for i := range light.Genres {
		if light.Genres[i] != heavy.Genres[i] {
			t.Fatalf("entry %d: %+v vs %+v", i, light.Genres[i], heavy.Genres[i])
		}
	}
}

// An empty or nonsensical reading has to come back as an empty *list* rather than as null,
// because the television reads "no genres" as "use the default order" and a null would be
// one more shape for it to have an opinion about.
func TestNormaliseGenreAffinityRefusesToInventWeights(t *testing.T) {
	for name, affinity := range map[string]store.GenreAffinity{
		"nothing watched": {},
		"all zero":        {Sessions: 5, Genres: []store.GenreWeight{{Genre: "Drama"}}},
		"negative":        {Sessions: 5, Genres: []store.GenreWeight{{Genre: "Drama", Score: -2}}},
	} {
		response := normaliseGenreAffinity(affinity)
		if response.Genres == nil {
			t.Fatalf("%s: genres is nil, want an empty list", name)
		}
		if len(response.Genres) != 0 {
			t.Fatalf("%s: genres = %+v, want none", name, response.Genres)
		}
	}
}

// A blank label cannot be matched against anything on the television, so it is dropped
// rather than sent as a row with a weight the set would have to know to ignore.
func TestNormaliseGenreAffinityDropsBlankLabels(t *testing.T) {
	response := normaliseGenreAffinity(store.GenreAffinity{Sessions: 20, Genres: []store.GenreWeight{
		{Genre: "Drama", Score: 4}, {Genre: "", Score: 2},
	}})
	if len(response.Genres) != 1 || response.Genres[0].Genre != "Drama" {
		t.Fatalf("genres = %+v, want Drama alone", response.Genres)
	}
}