package domain

import "testing"

func TestPartitionTeamsBalancesMeanRatingBeforeOpposingSpread(t *testing.T) {
	players := []Candidate{
		{PlayerID: "a", Rating: 1000}, {PlayerID: "b", Rating: 1100},
		{PlayerID: "c", Rating: 1900}, {PlayerID: "d", Rating: 2000},
	}
	teams, err := PartitionTeams(players)
	if err != nil {
		t.Fatal(err)
	}
	if playerIDs(teams.Team0) != "a\x00d\x00" || playerIDs(teams.Team1) != "b\x00c\x00" {
		t.Fatalf("unexpected balanced partition: team0=%q team1=%q", playerIDs(teams.Team0), playerIDs(teams.Team1))
	}
}

func TestPartitionTeamsIsIndependentOfInputOrder(t *testing.T) {
	players := []Candidate{
		{PlayerID: "d", Rating: 1500}, {PlayerID: "b", Rating: 1500},
		{PlayerID: "c", Rating: 1500}, {PlayerID: "a", Rating: 1500},
	}
	first, err := PartitionTeams(players)
	if err != nil {
		t.Fatal(err)
	}
	second, err := PartitionTeams([]Candidate{players[2], players[0], players[3], players[1]})
	if err != nil {
		t.Fatal(err)
	}
	if playerIDs(first.Team0) != playerIDs(second.Team0) || playerIDs(first.Team1) != playerIDs(second.Team1) {
		t.Fatalf("input order changed partition: first=%q/%q second=%q/%q", playerIDs(first.Team0), playerIDs(first.Team1), playerIDs(second.Team0), playerIDs(second.Team1))
	}
}

func TestPartitionTeamsRejectsUnsupportedShapes(t *testing.T) {
	for _, count := range []int{0, 1, 3, 7} {
		players := make([]Candidate, count)
		if _, err := PartitionTeams(players); err == nil {
			t.Fatalf("accepted %d players", count)
		}
	}
}