package handler

import (
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"
)

// TestGetRuntimeUsage_BucketsByUsageTime ensures a task that was enqueued on
// one calendar day but whose tokens were reported the next day (e.g. execution
// crossed midnight, or the task sat in the queue) is attributed to the day
// tokens were actually produced, not the enqueue day. It also verifies the
// ?days=N cutoff covers the full earliest calendar day, not just "now minus N
// days" which would clip the morning of that day.
func TestGetRuntimeUsage_BucketsByUsageTime(t *testing.T) {
	if testHandler == nil {
		t.Skip("database not available")
	}
	ctx := context.Background()

	// Pick a runtime bound to the fixture workspace.
	var runtimeID string
	if err := testPool.QueryRow(ctx, `
		SELECT id FROM agent_runtime WHERE workspace_id = $1 LIMIT 1
	`, testWorkspaceID).Scan(&runtimeID); err != nil {
		t.Fatalf("fetch runtime: %v", err)
	}
	var agentID string
	if err := testPool.QueryRow(ctx, `
		SELECT id FROM agent WHERE workspace_id = $1 LIMIT 1
	`, testWorkspaceID).Scan(&agentID); err != nil {
		t.Fatalf("fetch agent: %v", err)
	}

	// Create an issue for the tasks to reference.
	var issueID string
	if err := testPool.QueryRow(ctx, `
		INSERT INTO issue (workspace_id, title, creator_id, creator_type)
		VALUES ($1, 'runtime usage test', $2, 'member')
		RETURNING id
	`, testWorkspaceID, testUserID).Scan(&issueID); err != nil {
		t.Fatalf("create issue: %v", err)
	}
	t.Cleanup(func() {
		testPool.Exec(ctx, `DELETE FROM issue WHERE id = $1`, issueID)
	})

	// enqueued yesterday 23:58 UTC, finished today 00:05 UTC — tokens belong to today.
	now := time.Now().UTC()
	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, time.UTC)
	yesterdayLate := today.Add(-2 * time.Minute)
	todayEarly := today.Add(5 * time.Minute)
	// Task that ran entirely yesterday around 05:00 — used to verify the
	// ?days cutoff isn't clipping yesterday's morning.
	yesterdayMorning := today.Add(-19 * time.Hour)

	insertTaskWithUsage := func(enqueueAt, usageAt time.Time, inputTokens int64) string {
		var taskID string
		if err := testPool.QueryRow(ctx, `
			INSERT INTO agent_task_queue (agent_id, issue_id, runtime_id, status, created_at)
			VALUES ($1, $2, $3, 'completed', $4)
			RETURNING id
		`, agentID, issueID, runtimeID, enqueueAt).Scan(&taskID); err != nil {
			t.Fatalf("insert task: %v", err)
		}
		if _, err := testPool.Exec(ctx, `
			INSERT INTO task_usage (task_id, provider, model, input_tokens, output_tokens, created_at)
			VALUES ($1, 'claude', 'claude-3-5-sonnet', $2, 0, $3)
		`, taskID, inputTokens, usageAt); err != nil {
			t.Fatalf("insert task_usage: %v", err)
		}
		t.Cleanup(func() {
			testPool.Exec(ctx, `DELETE FROM agent_task_queue WHERE id = $1`, taskID)
		})
		return taskID
	}

	insertTaskWithUsage(yesterdayLate, todayEarly, 1000)     // cross-midnight
	insertTaskWithUsage(yesterdayMorning, yesterdayMorning, 2000) // full-day yesterday

	// Call the handler with ?days=1 at whatever "now" is. That should include
	// both today and yesterday in full.
	w := httptest.NewRecorder()
	req := newRequest("GET", "/api/runtimes/"+runtimeID+"/usage?days=1", nil)
	req = withURLParam(req, "runtimeId", runtimeID)
	testHandler.GetRuntimeUsage(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("GetRuntimeUsage: expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var resp []RuntimeUsageResponse
	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
		t.Fatalf("decode response: %v", err)
	}

	byDate := make(map[string]int64)
	for _, r := range resp {
		byDate[r.Date] += r.InputTokens
	}

	todayKey := today.Format("2006-01-02")
	yesterdayKey := today.Add(-24 * time.Hour).Format("2006-01-02")

	// Cross-midnight task must attribute to today (tu.created_at), not yesterday
	// (atq.created_at). Before the fix this was 0 on today / 1000 on yesterday.
	if byDate[todayKey] != 1000 {
		t.Errorf("cross-midnight task: today bucket expected 1000 input tokens, got %d (full map: %v)", byDate[todayKey], byDate)
	}
	// Yesterday's morning task must still be included — this is what breaks
	// when ?days=N is interpreted as a rolling window instead of calendar days.
	if byDate[yesterdayKey] != 2000 {
		t.Errorf("yesterday morning task: yesterday bucket expected 2000 input tokens, got %d (full map: %v)", byDate[yesterdayKey], byDate)
	}
}