package prizepool

import (
	"context"
	"errors"
	"testing"
)

func TestPickAvailableSkipsUnavailableItems(t *testing.T) {
	counter := UserIssueCounterFunc(func(_ context.Context, itemID int64, userID int64) (int64, error) {
		if itemID == 4 && userID == 1001 {
			return 1, nil
		}
		return 0, nil
	})
	picker := Picker{RandomIntn: func(max int) (int, error) {
		if max != 7 {
			t.Fatalf("max = %d, want 7", max)
		}
		return 6, nil
	}}

	picked, err := picker.PickAvailable(context.Background(), []Item{
		{ID: 1, Enabled: false, Weight: 100},
		{ID: 2, Enabled: true, Weight: 0},
		{ID: 3, Enabled: true, Weight: 5, TotalLimit: 10, IssuedCount: 10},
		{ID: 4, Enabled: true, Weight: 8, UserLimit: 1},
		{ID: 5, Enabled: true, Weight: 7},
	}, 1001, counter)
	if err != nil {
		t.Fatalf("PickAvailable() error = %v", err)
	}
	if picked.Item.ID != 5 || picked.Index != 4 {
		t.Fatalf("picked = %+v, want item 5 at original index 4", picked)
	}
}

func TestPickAvailableNoAvailableItem(t *testing.T) {
	_, err := Picker{}.PickAvailable(context.Background(), []Item{
		{ID: 1, Enabled: true, Weight: 1, TotalLimit: 1, IssuedCount: 1},
	}, 1001, nil)
	if !errors.Is(err, ErrNoAvailableItem) {
		t.Fatalf("error = %v, want ErrNoAvailableItem", err)
	}
}

func TestPickAvailableRequiresCounterForUserLimit(t *testing.T) {
	_, err := Picker{}.PickAvailable(context.Background(), []Item{
		{ID: 1, Enabled: true, Weight: 1, UserLimit: 1},
	}, 1001, nil)
	if !errors.Is(err, ErrUserIssueCounterRequired) {
		t.Fatalf("error = %v, want ErrUserIssueCounterRequired", err)
	}
}

func TestPickWeightedUsesWeights(t *testing.T) {
	picker := Picker{RandomIntn: func(max int) (int, error) {
		if max != 10 {
			t.Fatalf("max = %d, want 10", max)
		}
		return 3, nil
	}}

	picked, err := picker.PickWeighted([]PickResult{
		{Item: Item{ID: 1, Enabled: true, Weight: 3}, Index: 0},
		{Item: Item{ID: 2, Enabled: true, Weight: 7}, Index: 1},
	})
	if err != nil {
		t.Fatalf("PickWeighted() error = %v", err)
	}
	if picked.Item.ID != 2 {
		t.Fatalf("picked item = %d, want 2", picked.Item.ID)
	}
}