package chat

import (
	"context"
	"testing"
	"time"

	"github.com/google/uuid"
	"github.com/stretchr/testify/require"
)

// usageRepo is a tiny stub that records what was called and returns canned values.
// It satisfies only the UsageService-relevant subset of Repository; unused methods
// inherit panic stubs from fakeRepo so we don't need to declare them here.
type usageRepo struct {
	*fakeRepo

	insertedUsage []UsageRecord

	byUserCalls  []timeRange
	byModelCalls []timeRange
	byDayCalls   []timeRange
	dailyCalls   []userTimeRange

	usersOut  []UserUsageRow
	modelsOut []ModelUsageRow
	daysOut   []DayUsageRow
}

type timeRange struct{ from, to time.Time }
type userTimeRange struct {
	user uuid.UUID
	from time.Time
	to   time.Time
}

func (r *usageRepo) InsertUsage(_ context.Context, rec UsageRecord) error {
	r.insertedUsage = append(r.insertedUsage, rec)
	return nil
}
func (r *usageRepo) SummarizeUsageByUser(_ context.Context, from, to time.Time) ([]UserUsageRow, error) {
	r.byUserCalls = append(r.byUserCalls, timeRange{from, to})
	return r.usersOut, nil
}
func (r *usageRepo) SummarizeUsageByModel(_ context.Context, from, to time.Time) ([]ModelUsageRow, error) {
	r.byModelCalls = append(r.byModelCalls, timeRange{from, to})
	return r.modelsOut, nil
}
func (r *usageRepo) SummarizeUsageByDay(_ context.Context, from, to time.Time) ([]DayUsageRow, error) {
	r.byDayCalls = append(r.byDayCalls, timeRange{from, to})
	return r.daysOut, nil
}
func (r *usageRepo) SummarizeUserDaily(_ context.Context, uid uuid.UUID, from, to time.Time) ([]DayUsageRow, error) {
	r.dailyCalls = append(r.dailyCalls, userTimeRange{uid, from, to})
	return r.daysOut, nil
}

func TestUsageService_DelegatesToRepo(t *testing.T) {
	repo := &usageRepo{fakeRepo: newFakeRepo()}
	svc := NewUsageService(repo)
	from := time.Date(2026, 5, 1, 0, 0, 0, 0, time.UTC)
	to := from.Add(24 * time.Hour)
	uid := uuid.Must(uuid.NewV7())

	rec := UsageRecord{
		ConversationID: uuid.Must(uuid.NewV7()),
		MessageID:      42,
		UserID:         uid,
		PromptTokens:   100, CompletionTokens: 50, ThinkingTokens: 0,
		CostUSD: 0.001,
	}
	require.NoError(t, svc.Insert(context.Background(), rec))
	require.Len(t, repo.insertedUsage, 1)
	require.Equal(t, rec, repo.insertedUsage[0])

	repo.usersOut = []UserUsageRow{{UserID: uid, PromptTokens: 100}}
	users, err := svc.SummarizeByUser(context.Background(), from, to)
	require.NoError(t, err)
	require.Equal(t, repo.usersOut, users)
	require.Equal(t, []timeRange{{from, to}}, repo.byUserCalls)

	repo.modelsOut = []ModelUsageRow{{ModelID: uuid.Must(uuid.NewV7()), CostUSD: 1.5}}
	models, err := svc.SummarizeByModel(context.Background(), from, to)
	require.NoError(t, err)
	require.Equal(t, repo.modelsOut, models)
	require.Equal(t, []timeRange{{from, to}}, repo.byModelCalls)

	repo.daysOut = []DayUsageRow{{Day: from, PromptTokens: 200}}
	days, err := svc.SummarizeByDay(context.Background(), from, to)
	require.NoError(t, err)
	require.Equal(t, repo.daysOut, days)
	require.Equal(t, []timeRange{{from, to}}, repo.byDayCalls)

	dailyOut, err := svc.UserDaily(context.Background(), uid, from, to)
	require.NoError(t, err)
	require.Equal(t, repo.daysOut, dailyOut)
	require.Equal(t, []userTimeRange{{uid, from, to}}, repo.dailyCalls)
}