package main

import (
	"bufio"
	"bytes"
	"context"
	"crypto/sha256"
	"crypto/tls"
	"crypto/x509"
	"encoding/base64"
	"encoding/binary"
	"encoding/hex"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"hash/crc32"
	"io"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"sync"
	"syscall"
	"time"

	"github.com/easyai/easyai-ai-gateway/apps/api/internal/acceptanceworkload"
)

const (
	runHeader      = "X-EasyAI-Acceptance-Run"
	tokenHeader    = "X-EasyAI-Acceptance-Token"
	upstreamHeader = "X-EasyAI-Acceptance-Upstream"
)

var reportURLPattern = regexp.MustCompile(`(?i)(?:https?|postgres(?:ql)?):\/\/[^\s"'<>]+`)

type options struct {
	gateways       []string
	gatewayTLSName string
	gatewayCAFile  string
	emulatorURL    string
	apiKeys        []string
	runID          string
	runToken       string
	geminiModel    string
	videoModel     string
	profile        string
	reportPath     string
	realImageURLs  []string
	timeout        time.Duration
	mixedDuration  time.Duration
	imageRate      float64
	videoRate      float64
}

type report struct {
	SchemaVersion    string        `json:"schemaVersion"`
	RunID            string        `json:"runId"`
	Profile          string        `json:"profile"`
	StartedAt        time.Time     `json:"startedAt"`
	FinishedAt       time.Time     `json:"finishedAt"`
	Passed           bool          `json:"passed"`
	Phases           []phaseReport `json:"phases"`
	Failure          string        `json:"failure,omitempty"`
	FailureOperation string        `json:"failureOperation,omitempty"`
	SecretSafe       bool          `json:"secretSafe"`
}

type phaseReport struct {
	Name                  string  `json:"name"`
	Requests              int     `json:"requests"`
	Completed             int     `json:"completed"`
	Failed                int     `json:"failed"`
	DurationMS            int64   `json:"durationMs"`
	SubmissionDurationMS  int64   `json:"submissionDurationMs,omitempty"`
	P50MS                 float64 `json:"p50Ms"`
	P95MS                 float64 `json:"p95Ms"`
	P99MS                 float64 `json:"p99Ms"`
	DecodedOutputBytes    int64   `json:"decodedOutputBytes,omitempty"`
	OutputSHA256          string  `json:"outputSha256,omitempty"`
	UniqueTaskIDs         int     `json:"uniqueTaskIds,omitempty"`
	UniqueImageCombos     int     `json:"uniqueImageCombinations,omitempty"`
	ForcedConversionTasks int     `json:"forcedConversionTasks,omitempty"`
	Throttled             int     `json:"throttled,omitempty"`
	Unexpected5xx         int     `json:"unexpected5xx,omitempty"`
	OfferedRatePerSecond  float64 `json:"offeredRatePerSecond,omitempty"`
}

type phaseResult struct {
	report    phaseReport
	latencies []time.Duration
	err       error
}

type httpStatusError struct {
	Status int
	Body   string
}

type operationError struct {
	Operation string
	Err       error
}

func (e *operationError) Error() string { return e.Operation + ": " + e.Err.Error() }
func (e *operationError) Unwrap() error { return e.Err }

func withOperation(operation string, err error) error {
	if err == nil {
		return nil
	}
	var existing *operationError
	if errors.As(err, &existing) {
		return err
	}
	return &operationError{Operation: operation, Err: err}
}

func (e *httpStatusError) Error() string {
	return fmt.Sprintf("HTTP %d: %s", e.Status, e.Body)
}

func main() {
	opts, err := parseOptions()
	if err != nil {
		fmt.Fprintln(os.Stderr, "acceptance load configuration error:", err)
		os.Exit(2)
	}
	signalContext, stopSignals := signal.NotifyContext(
		context.Background(),
		os.Interrupt,
		syscall.SIGTERM,
	)
	defer stopSignals()
	ctx, cancel := context.WithTimeout(signalContext, opts.timeout)
	defer cancel()
	result := report{
		SchemaVersion: "acceptance-load-report/v1",
		RunID:         opts.runID, Profile: opts.profile, StartedAt: time.Now().UTC(), SecretSafe: true,
	}
	phaseResults, runErr := run(ctx, opts)
	for _, phase := range phaseResults {
		phase.report.P50MS = percentileMilliseconds(phase.latencies, 0.50)
		phase.report.P95MS = percentileMilliseconds(phase.latencies, 0.95)
		phase.report.P99MS = percentileMilliseconds(phase.latencies, 0.99)
		result.Phases = append(result.Phases, phase.report)
		if runErr == nil && phase.err != nil {
			runErr = phase.err
		}
	}
	result.FinishedAt = time.Now().UTC()
	result.Passed = runErr == nil
	if runErr != nil {
		result.Failure = redactError(runErr.Error(), opts)
		var operationErr *operationError
		if errors.As(runErr, &operationErr) {
			result.FailureOperation = operationErr.Operation
		}
	}
	payload, _ := json.MarshalIndent(result, "", "  ")
	fmt.Println(string(payload))
	if opts.reportPath != "" {
		if err := writeReportExclusive(opts.reportPath, payload); err != nil {
			fmt.Fprintln(os.Stderr, "write acceptance report failed:", err)
			os.Exit(1)
		}
	}
	if runErr != nil {
		os.Exit(1)
	}
}

func writeReportExclusive(path string, payload []byte) error {
	reportFile, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o600)
	if err != nil {
		return err
	}
	if _, err := reportFile.Write(append(payload, '\n')); err != nil {
		_ = reportFile.Close()
		return err
	}
	return reportFile.Close()
}

func parseOptions() (options, error) {
	var profile string
	var reportPath string
	var timeout time.Duration
	var mixedDuration time.Duration
	var imageRate float64
	var videoRate float64
	flag.StringVar(&profile, "profile", env("AI_GATEWAY_ACCEPTANCE_PROFILE", "simulated-all"), "simulated-all, Gemini profile, video profile, or real-canary")
	flag.StringVar(&reportPath, "report", env("AI_GATEWAY_ACCEPTANCE_REPORT", ""), "secret-safe JSON report path")
	flag.DurationVar(&timeout, "timeout", 45*time.Minute, "overall timeout")
	flag.DurationVar(&mixedDuration, "duration", envDuration("AI_GATEWAY_ACCEPTANCE_MIXED_DURATION", 10*time.Minute), "mixed workload duration")
	flag.Float64Var(&imageRate, "image-rate", envFloat("AI_GATEWAY_ACCEPTANCE_IMAGE_RATE", 0), "mixed image requests per second")
	flag.Float64Var(&videoRate, "video-rate", envFloat("AI_GATEWAY_ACCEPTANCE_VIDEO_RATE", 0), "mixed video requests per second")
	flag.Parse()
	opts := options{
		gateways:       splitCSV(os.Getenv("AI_GATEWAY_ACCEPTANCE_GATEWAYS")),
		gatewayTLSName: strings.TrimSpace(os.Getenv("AI_GATEWAY_ACCEPTANCE_GATEWAY_TLS_SERVER_NAME")),
		gatewayCAFile:  strings.TrimSpace(os.Getenv("AI_GATEWAY_ACCEPTANCE_GATEWAY_CA_FILE")),
		emulatorURL:    strings.TrimRight(strings.TrimSpace(os.Getenv("AI_GATEWAY_ACCEPTANCE_EMULATOR_URL")), "/"),
		apiKeys:        splitCSV(env("AI_GATEWAY_ACCEPTANCE_API_KEYS", os.Getenv("AI_GATEWAY_ACCEPTANCE_API_KEY"))),
		runID:          strings.TrimSpace(os.Getenv("AI_GATEWAY_ACCEPTANCE_RUN_ID")),
		runToken:       strings.TrimSpace(os.Getenv("AI_GATEWAY_ACCEPTANCE_RUN_TOKEN")),
		geminiModel:    strings.TrimSpace(os.Getenv("AI_GATEWAY_ACCEPTANCE_GEMINI_MODEL")),
		videoModel:     strings.TrimSpace(os.Getenv("AI_GATEWAY_ACCEPTANCE_VIDEO_MODEL")),
		profile:        strings.ToLower(strings.TrimSpace(profile)),
		reportPath:     strings.TrimSpace(reportPath),
		realImageURLs:  splitCSV(os.Getenv("AI_GATEWAY_ACCEPTANCE_REAL_IMAGE_URLS")),
		timeout:        timeout,
		mixedDuration:  mixedDuration,
		imageRate:      imageRate,
		videoRate:      videoRate,
	}
	if len(opts.gateways) != 2 {
		return options{}, errors.New("AI_GATEWAY_ACCEPTANCE_GATEWAYS must contain exactly two API base URLs")
	}
	for index := range opts.gateways {
		opts.gateways[index] = strings.TrimRight(opts.gateways[index], "/")
		if _, err := url.ParseRequestURI(opts.gateways[index]); err != nil {
			return options{}, fmt.Errorf("gateway %d URL is invalid", index+1)
		}
	}
	if opts.gatewayTLSName != "" &&
		(strings.ContainsAny(opts.gatewayTLSName, "/:@") || !strings.Contains(opts.gatewayTLSName, ".")) {
		return options{}, errors.New("AI_GATEWAY_ACCEPTANCE_GATEWAY_TLS_SERVER_NAME must be a DNS hostname")
	}
	if len(opts.apiKeys) == 0 || opts.runID == "" || opts.runToken == "" {
		return options{}, errors.New("acceptance API key, Run ID, and Run Token environment variables are required")
	}
	if opts.geminiModel == "" || opts.videoModel == "" {
		return options{}, errors.New("Gemini and video model environment variables are required")
	}
	if opts.timeout <= 0 {
		return options{}, errors.New("timeout must be positive")
	}
	switch opts.profile {
	case "simulated-smoke", "simulated-all", "gemini-baseline", "gemini-large", "gemini-peak", "video-throughput", "video-recovery",
		"mixed-soak", "mixed-overload":
		if opts.emulatorURL == "" {
			return options{}, errors.New("AI_GATEWAY_ACCEPTANCE_EMULATOR_URL is required for simulated profiles")
		}
		if (opts.profile == "mixed-soak" || opts.profile == "mixed-overload") &&
			(opts.mixedDuration <= 0 || opts.imageRate < 0 || opts.videoRate < 0 ||
				opts.imageRate+opts.videoRate <= 0) {
			return options{}, errors.New("mixed profiles require a positive duration and offered rate")
		}
	case "real-canary":
		if len(opts.realImageURLs) < 3 {
			return options{}, errors.New("real-canary requires at least three public AI_GATEWAY_ACCEPTANCE_REAL_IMAGE_URLS")
		}
	default:
		return options{}, fmt.Errorf("unsupported profile %q", opts.profile)
	}
	return opts, nil
}

func run(ctx context.Context, opts options) ([]phaseResult, error) {
	var tlsConfig *tls.Config
	if opts.gatewayTLSName != "" || opts.gatewayCAFile != "" {
		rootCAs, err := acceptanceRootCAs(opts.gatewayCAFile)
		if err != nil {
			return nil, err
		}
		tlsConfig = &tls.Config{
			MinVersion: tls.VersionTLS12,
			ServerName: opts.gatewayTLSName,
			RootCAs:    rootCAs,
		}
	}
	client := &http.Client{
		Timeout: opts.timeout,
		Transport: &http.Transport{
			MaxIdleConns:        2048,
			MaxIdleConnsPerHost: 1024,
			MaxConnsPerHost:     1024,
			ForceAttemptHTTP2:   true,
			TLSClientConfig:     tlsConfig,
		},
	}
	results := make([]phaseResult, 0, 5)
	runPhase := func(name string) error {
		var result phaseResult
		if profile, ok := acceptanceworkload.GeminiProfileByName(name); ok {
			result = runGemini(ctx, client, opts, name, profile.Requests, profile.InputBytes, profile.OutputBytes, false)
		} else {
			switch name {
			case "smoke-gemini":
				result = runGemini(ctx, client, opts, name, 4, 256<<10, 256<<10, false)
			case "smoke-video":
				result = runVideo(ctx, client, opts, name, 10, false, opts.emulatorFixtureURLs(), false, 0)
			case "video-throughput":
				result = runVideo(ctx, client, opts, name, 1200, false, opts.emulatorFixtureURLs(), false, 0)
			case "video-recovery":
				result = runVideo(ctx, client, opts, name, 96, true, opts.emulatorFixtureURLs(), false, 0)
			case "mixed-soak", "mixed-overload":
				result = runMixed(ctx, client, opts, name == "mixed-overload")
			case "real-gemini-canary":
				result = runGemini(ctx, client, opts, name, 1, 256<<10, 0, true)
			case "real-video-canary":
				result = runVideo(ctx, client, opts, name, 1, false, opts.realImageURLs, true, 0)
			default:
				return fmt.Errorf("unknown phase %q", name)
			}
		}
		results = append(results, result)
		return result.err
	}
	phases := []string{opts.profile}
	if opts.profile == "simulated-smoke" {
		phases = []string{"smoke-gemini", "smoke-video"}
	} else if opts.profile == "simulated-all" {
		phases = []string{"gemini-baseline", "gemini-large", "gemini-peak", "video-throughput", "video-recovery"}
	} else if opts.profile == "real-canary" {
		phases = []string{"real-gemini-canary", "real-video-canary"}
	}
	for _, phase := range phases {
		if err := runPhase(phase); err != nil {
			return results, err
		}
	}
	return results, nil
}

func runGemini(
	ctx context.Context,
	client *http.Client,
	opts options,
	name string,
	requestCount int,
	inputBytes int,
	expectedOutputBytes int,
	realUpstream bool,
) phaseResult {
	startedAt := time.Now()
	expectedHash := ""
	if expectedOutputBytes > 0 {
		sum := sha256.Sum256(paddedPNG(expectedOutputBytes))
		expectedHash = hex.EncodeToString(sum[:])
	}
	latencies := make([]time.Duration, requestCount)
	var decodedBytes int64
	var completed int
	var failures int
	var firstErr error
	var mu sync.Mutex
	slots := make(chan struct{}, requestCount)
	var wg sync.WaitGroup
	for index := 0; index < requestCount; index++ {
		index := index
		wg.Add(1)
		go func() {
			defer wg.Done()
			select {
			case slots <- struct{}{}:
			case <-ctx.Done():
				return
			}
			defer func() { <-slots }()
			requestStarted := time.Now()
			endpoint := opts.gateways[index%len(opts.gateways)] + "/v1beta/models/" + url.PathEscape(opts.geminiModel) + ":generateContent"
			requestBody := streamGeminiRequestBody(paddedPNGVariant(inputBytes, index+1))
			req, err := http.NewRequestWithContext(
				ctx,
				http.MethodPost,
				endpoint,
				requestBody,
			)
			if err != nil {
				_ = requestBody.Close()
			}
			if err == nil {
				opts.setHeaders(req, index, realUpstream)
				req.Header.Set("Content-Type", "application/json")
				var response *http.Response
				response, err = client.Do(req)
				if err == nil {
					if response.StatusCode != http.StatusOK {
						err = withOperation("gemini_submit", responseStatusError(response))
					} else {
						var size int64
						var outputHash string
						size, outputHash, err = streamGeminiImageHash(response.Body)
						err = withOperation("gemini_response", err)
						_ = response.Body.Close()
						if err == nil && expectedOutputBytes > 0 && (size != int64(expectedOutputBytes) || outputHash != expectedHash) {
							err = withOperation("gemini_response", fmt.Errorf("Gemini output mismatch: bytes=%d hash=%s", size, outputHash))
						}
						if err == nil {
							mu.Lock()
							decodedBytes += size
							if expectedHash == "" {
								expectedHash = outputHash
							}
							mu.Unlock()
						}
					}
				}
			}
			err = withOperation("gemini_submit", err)
			latency := time.Since(requestStarted)
			mu.Lock()
			latencies[index] = latency
			if err != nil {
				failures++
				if firstErr == nil {
					firstErr = err
				}
			} else {
				completed++
			}
			mu.Unlock()
		}()
	}
	wg.Wait()
	elapsed := time.Since(startedAt)
	result := phaseReport{
		Name: name, Requests: requestCount, Completed: completed, Failed: failures,
		DurationMS: elapsed.Milliseconds(), DecodedOutputBytes: decodedBytes, OutputSHA256: expectedHash,
	}
	if firstErr == nil && name == "gemini-baseline" && elapsed > 8*time.Minute {
		firstErr = fmt.Errorf("Gemini baseline exceeded 8 minutes: %s", elapsed)
	}
	if firstErr == nil && completed != requestCount {
		firstErr = fmt.Errorf("Gemini completed %d of %d requests", completed, requestCount)
	}
	return phaseResult{report: result, latencies: latencies, err: firstErr}
}

func streamGeminiRequestBody(input []byte) io.ReadCloser {
	reader, writer := io.Pipe()
	go func() {
		closeWithError := func(err error) {
			_ = writer.CloseWithError(err)
		}
		if _, err := io.WriteString(writer, `{"contents":[{"role":"user","parts":[{"text":"将参考图编辑为蓝色赛博朋克风格，保留主体结构"},{"inlineData":{"mimeType":"image/png","data":"`); err != nil {
			closeWithError(err)
			return
		}
		encoder := base64.NewEncoder(base64.StdEncoding, writer)
		if _, err := encoder.Write(input); err != nil {
			closeWithError(err)
			return
		}
		if err := encoder.Close(); err != nil {
			closeWithError(err)
			return
		}
		if _, err := io.WriteString(writer, `"}}]}],"generationConfig":{"responseModalities":["IMAGE"]}}`); err != nil {
			closeWithError(err)
			return
		}
		_ = writer.Close()
	}()
	return reader
}

func runVideo(
	ctx context.Context,
	client *http.Client,
	opts options,
	name string,
	requestCount int,
	longRun bool,
	imageURLs []string,
	realUpstream bool,
	requestOffset int,
) phaseResult {
	startedAt := time.Now()
	combinationCount := 128
	if realUpstream {
		combinationCount = 1
	}
	combinations := videoCombinations(imageURLs, combinationCount)
	var taskIDs = make([]string, requestCount)
	latencies := make([]time.Duration, requestCount)
	startedTasks := make([]time.Time, requestCount)
	var completed int
	var failures int
	var forcedConversions int
	var firstErr error
	var mu sync.Mutex
	var wg sync.WaitGroup
	submitStartedAt := time.Now()
	for index := 0; index < requestCount; index++ {
		index := index
		wg.Add(1)
		go func() {
			defer wg.Done()
			logicalIndex := index + requestOffset
			requestStarted := time.Now()
			startedTasks[index] = requestStarted
			imageCount := acceptanceworkload.VideoImageCount(logicalIndex)
			combo := append([]string(nil), combinations[logicalIndex%len(combinations)]...)
			if len(combo) > imageCount {
				combo = combo[:imageCount]
			}
			if !realUpstream && logicalIndex%4 == 0 {
				combo[0] = imageURLs[12+(logicalIndex/4)%4]
			}
			content := make([]any, 0, len(combo)+1)
			prompt := "多参考图生成连续运镜视频，保持人物、服装和场景一致"
			if longRun {
				prompt += " acceptance-long-recovery"
			}
			if !realUpstream && logicalIndex%4 == 0 {
				prompt += " acceptance-force-conversion"
			}
			content = append(content, map[string]any{"type": "text", "text": prompt})
			for imageIndex, imageURL := range combo {
				role := "reference_image"
				if logicalIndex%5 == 0 && imageIndex == 0 {
					role = "first_frame"
				}
				if logicalIndex%5 == 0 && len(combo) > 3 && imageIndex == len(combo)-1 {
					role = "last_frame"
				}
				content = append(content, map[string]any{
					"type": "image_url", "role": role,
					"image_url": map[string]any{"url": imageURL},
				})
			}
			body, _ := json.Marshal(map[string]any{
				"model": opts.videoModel, "modelType": "omni_video", "content": content, "seed": logicalIndex + 1,
				"duration": 5, "ratio": "16:9", "resolution": "720p",
			})
			endpoint := opts.gateways[logicalIndex%len(opts.gateways)] + "/api/v1/videos/generations"
			req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, bytes.NewReader(body))
			if err == nil {
				opts.setHeaders(req, logicalIndex, realUpstream)
				req.Header.Set("Content-Type", "application/json")
				req.Header.Set("X-Async", "true")
				var response *http.Response
				response, err = client.Do(req)
				if err == nil {
					if response.StatusCode != http.StatusAccepted {
						err = withOperation("video_submit", responseStatusError(response))
					} else {
						var accepted struct {
							TaskID string `json:"taskId"`
						}
						err = json.NewDecoder(io.LimitReader(response.Body, 1<<20)).Decode(&accepted)
						_ = response.Body.Close()
						taskIDs[index] = strings.TrimSpace(accepted.TaskID)
						if err == nil && taskIDs[index] == "" {
							err = errors.New("video acceptance response did not include taskId")
						}
					}
				}
			}
			err = withOperation("video_submit", err)
			mu.Lock()
			latencies[index] = time.Since(requestStarted)
			if !realUpstream && logicalIndex%4 == 0 {
				forcedConversions++
			}
			if err != nil {
				failures++
				if firstErr == nil {
					firstErr = err
				}
			}
			mu.Unlock()
		}()
	}
	wg.Wait()
	submissionDuration := time.Since(submitStartedAt)
	if firstErr == nil && name == "video-throughput" && submissionDuration > 10*time.Second {
		firstErr = fmt.Errorf("1200 video submissions exceeded 10 seconds: %s", submissionDuration)
	}
	uniqueTaskIDs := map[string]struct{}{}
	for _, taskID := range taskIDs {
		if taskID != "" {
			uniqueTaskIDs[taskID] = struct{}{}
		}
	}
	if firstErr == nil && len(uniqueTaskIDs) != requestCount {
		firstErr = fmt.Errorf("video task IDs are not unique: unique=%d requests=%d", len(uniqueTaskIDs), requestCount)
	}
	pollSlots := make(chan struct{}, 256)
	for index, taskID := range taskIDs {
		if taskID == "" {
			continue
		}
		index, taskID := index, taskID
		logicalIndex := index + requestOffset
		wg.Add(1)
		go func() {
			defer wg.Done()
			select {
			case pollSlots <- struct{}{}:
			case <-ctx.Done():
				return
			}
			defer func() { <-pollSlots }()
			err := pollVideoTask(ctx, client, opts, taskID, logicalIndex, realUpstream)
			mu.Lock()
			latencies[index] = time.Since(startedTasks[index])
			if err != nil {
				failures++
				if firstErr == nil {
					firstErr = err
				}
			} else {
				completed++
			}
			mu.Unlock()
		}()
	}
	wg.Wait()
	comboSet := map[string]struct{}{}
	for _, combo := range combinations {
		comboSet[strings.Join(combo, "\x00")] = struct{}{}
	}
	if firstErr == nil && !realUpstream && len(comboSet) != 128 {
		firstErr = fmt.Errorf("video image combinations=%d, want 128", len(comboSet))
	}
	elapsed := time.Since(startedAt)
	result := phaseReport{
		Name: name, Requests: requestCount, Completed: completed, Failed: failures,
		DurationMS: elapsed.Milliseconds(), SubmissionDurationMS: submissionDuration.Milliseconds(),
		UniqueTaskIDs: len(uniqueTaskIDs), UniqueImageCombos: len(comboSet),
		ForcedConversionTasks: forcedConversions,
	}
	if firstErr == nil && completed != requestCount {
		firstErr = fmt.Errorf("video completed %d of %d tasks", completed, requestCount)
	}
	return phaseResult{report: result, latencies: latencies, err: firstErr}
}

func runMixed(
	ctx context.Context,
	client *http.Client,
	opts options,
	expectThrottling bool,
) phaseResult {
	runCtx, stopRun := context.WithCancel(ctx)
	defer stopRun()
	startedAt := time.Now()
	totalRate := opts.imageRate + opts.videoRate
	interval := time.Duration(float64(time.Second) / totalRate)
	if interval < time.Millisecond {
		interval = time.Millisecond
	}
	ticker := time.NewTicker(interval)
	defer ticker.Stop()
	stop := time.NewTimer(opts.mixedDuration)
	defer stop.Stop()
	slots := make(chan struct{}, 4096)
	var wg sync.WaitGroup
	var mu sync.Mutex
	latencies := make([]time.Duration, 0, int(totalRate*opts.mixedDuration.Seconds()))
	requests := 0
	completed := 0
	failed := 0
	throttled := 0
	unexpected5xx := 0
	var firstErr error
	imageAccumulator := float64(0)
	generating := true
	for generating {
		select {
		case <-runCtx.Done():
			generating = false
			if ctx.Err() != nil {
				mu.Lock()
				if firstErr == nil {
					firstErr = ctx.Err()
				}
				mu.Unlock()
			}
		case <-stop.C:
			generating = false
		case <-ticker.C:
			select {
			case slots <- struct{}{}:
			case <-runCtx.Done():
				generating = false
				continue
			}
			requestIndex := requests
			requests++
			imageAccumulator += opts.imageRate
			isImage := imageAccumulator >= totalRate
			if isImage {
				imageAccumulator -= totalRate
			}
			wg.Add(1)
			go func() {
				defer wg.Done()
				defer func() { <-slots }()
				var result phaseResult
				if isImage {
					result = runGemini(runCtx, client, opts, "mixed-image", 1, 256<<10, 256<<10, false)
				} else {
					result = runVideo(
						runCtx,
						client,
						opts,
						"mixed-video",
						1,
						false,
						opts.emulatorFixtureURLs(),
						false,
						requestIndex,
					)
				}
				latency := time.Since(startedAt)
				if len(result.latencies) > 0 {
					latency = result.latencies[0]
				}
				mu.Lock()
				defer mu.Unlock()
				latencies = append(latencies, latency)
				if result.err == nil {
					completed++
					return
				}
				var statusErr *httpStatusError
				if errors.As(result.err, &statusErr) && statusErr.Status == http.StatusTooManyRequests {
					throttled++
					if !expectThrottling && firstErr == nil {
						firstErr = result.err
						failed++
						stopRun()
					}
					return
				}
				if errors.As(result.err, &statusErr) && statusErr.Status >= 500 {
					unexpected5xx++
				}
				failed++
				if firstErr == nil {
					firstErr = result.err
					stopRun()
				}
			}()
		}
	}
	wg.Wait()
	if firstErr == nil && expectThrottling && throttled == 0 {
		firstErr = errors.New("mixed overload did not receive any 429 response")
	}
	if firstErr == nil && completed+throttled != requests {
		firstErr = fmt.Errorf(
			"mixed workload accounted for %d of %d requests",
			completed+throttled,
			requests,
		)
	}
	if firstErr == nil && unexpected5xx > 0 {
		firstErr = fmt.Errorf("mixed workload received %d unexpected 5xx responses", unexpected5xx)
	}
	return phaseResult{
		report: phaseReport{
			Name:                 map[bool]string{false: "mixed-soak", true: "mixed-overload"}[expectThrottling],
			Requests:             requests,
			Completed:            completed,
			Failed:               failed,
			DurationMS:           time.Since(startedAt).Milliseconds(),
			Throttled:            throttled,
			Unexpected5xx:        unexpected5xx,
			OfferedRatePerSecond: totalRate,
		},
		latencies: latencies,
		err:       firstErr,
	}
}

func pollVideoTask(ctx context.Context, client *http.Client, opts options, taskID string, index int, realUpstream bool) error {
	ticker := time.NewTicker(time.Second)
	defer ticker.Stop()
	for {
		endpoint := opts.gateways[index%len(opts.gateways)] + "/api/v1/ai/result/" + url.PathEscape(taskID)
		req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
		if err != nil {
			return withOperation("video_poll", err)
		}
		opts.setHeaders(req, index, realUpstream)
		response, err := client.Do(req)
		if err == nil {
			if response.StatusCode != http.StatusOK {
				err = responseStatusError(response)
			} else {
				var payload map[string]any
				err = json.NewDecoder(io.LimitReader(response.Body, 2<<20)).Decode(&payload)
				_ = response.Body.Close()
				status := strings.ToLower(strings.TrimSpace(fmt.Sprint(payload["status"])))
				switch status {
				case "succeeded", "success":
					mediaURL := findMediaURL(payload)
					if mediaURL == "" {
						return withOperation("video_poll", fmt.Errorf("video task %s succeeded without a media URL", taskID))
					}
					return withOperation("video_download", validateVideoAsset(ctx, client, opts, mediaURL, index))
				case "failed", "cancelled", "canceled":
					return withOperation("video_poll", fmt.Errorf("video task %s finished with status %s", taskID, status))
				}
			}
		}
		if err != nil {
			return withOperation("video_poll", err)
		}
		select {
		case <-ctx.Done():
			return withOperation("video_poll", ctx.Err())
		case <-ticker.C:
		}
	}
}

func findMediaURL(value any) string {
	switch typed := value.(type) {
	case map[string]any:
		preferredKeys := []string{"video_url", "url", "data", "content", "output", "result", "upload"}
		visited := make(map[string]struct{}, len(typed))
		for _, key := range preferredKeys {
			item, ok := typed[key]
			if !ok {
				continue
			}
			visited[key] = struct{}{}
			normalized := strings.ToLower(strings.TrimSpace(key))
			if (normalized == "url" || normalized == "video_url") && acceptanceMediaURL(strings.TrimSpace(fmt.Sprint(item))) {
				return strings.TrimSpace(fmt.Sprint(item))
			}
			if mediaURL := findMediaURL(item); mediaURL != "" {
				return mediaURL
			}
		}
		keys := make([]string, 0, len(typed)-len(visited))
		for key := range typed {
			if _, ok := visited[key]; !ok {
				keys = append(keys, key)
			}
		}
		sort.Strings(keys)
		for _, key := range keys {
			if mediaURL := findMediaURL(typed[key]); mediaURL != "" {
				return mediaURL
			}
		}
	case []any:
		for _, item := range typed {
			if mediaURL := findMediaURL(item); mediaURL != "" {
				return mediaURL
			}
		}
	}
	return ""
}

func acceptanceMediaURL(value string) bool {
	return strings.HasPrefix(value, "/") || strings.HasPrefix(value, "http://") || strings.HasPrefix(value, "https://")
}

func validateVideoAsset(ctx context.Context, client *http.Client, opts options, mediaURL string, index int) error {
	requestURL, gatewayRequest, err := acceptanceMediaRequestURL(opts, mediaURL, index)
	if err != nil {
		return fmt.Errorf("resolve final video: %w", err)
	}
	request, err := http.NewRequestWithContext(ctx, http.MethodGet, requestURL, nil)
	if err != nil {
		return err
	}
	if gatewayRequest {
		opts.setHeaders(request, index, false)
	}
	response, err := client.Do(request)
	if err != nil {
		return fmt.Errorf("download final video: %w", err)
	}
	defer response.Body.Close()
	if response.StatusCode < 200 || response.StatusCode >= 300 {
		return fmt.Errorf("download final video: HTTP %d", response.StatusCode)
	}
	payload, err := io.ReadAll(io.LimitReader(response.Body, 64<<10))
	if err != nil {
		return fmt.Errorf("read final video: %w", err)
	}
	contentType := strings.ToLower(strings.TrimSpace(response.Header.Get("Content-Type")))
	hasMP4Header := len(payload) >= 12 && string(payload[4:8]) == "ftyp"
	if len(payload) < 12 || (!strings.HasPrefix(contentType, "video/") && !hasMP4Header) {
		return fmt.Errorf("final video asset is invalid: bytes=%d content_type=%q", len(payload), contentType)
	}
	return nil
}

func acceptanceMediaRequestURL(opts options, mediaURL string, index int) (string, bool, error) {
	mediaURL = strings.TrimSpace(mediaURL)
	if mediaURL == "" {
		return "", false, errors.New("empty media URL")
	}
	if strings.HasPrefix(mediaURL, "/") {
		if len(opts.gateways) == 0 {
			return "", false, errors.New("no gateway URL configured")
		}
		base, err := url.Parse(opts.gateways[index%len(opts.gateways)])
		if err != nil {
			return "", false, err
		}
		reference, err := url.Parse(mediaURL)
		if err != nil {
			return "", false, err
		}
		return base.ResolveReference(reference).String(), true, nil
	}
	parsed, err := url.Parse(mediaURL)
	if err != nil {
		return "", false, err
	}
	if opts.gatewayTLSName == "" || !strings.EqualFold(parsed.Hostname(), opts.gatewayTLSName) {
		return parsed.String(), false, nil
	}
	if len(opts.gateways) == 0 {
		return "", false, errors.New("no gateway URL configured")
	}
	base, err := url.Parse(opts.gateways[index%len(opts.gateways)])
	if err != nil {
		return "", false, err
	}
	base.Path = parsed.Path
	base.RawPath = parsed.RawPath
	base.RawQuery = parsed.RawQuery
	base.Fragment = parsed.Fragment
	return base.String(), true, nil
}

func (o options) setHeaders(request *http.Request, requestIndex int, realUpstream bool) {
	if o.gatewayTLSName != "" {
		request.Host = o.gatewayTLSName
	}
	request.Header.Set("Authorization", "Bearer "+o.apiKeys[requestIndex%len(o.apiKeys)])
	request.Header.Set(runHeader, o.runID)
	request.Header.Set(tokenHeader, o.runToken)
	if realUpstream {
		request.Header.Set(upstreamHeader, "real")
	}
}

func (o options) emulatorFixtureURLs() []string {
	out := make([]string, 0, 16)
	for index := 0; index < 4; index++ {
		out = append(out, fmt.Sprintf("%s/fixtures/image-%02d.png", o.emulatorURL, index))
	}
	for index := 4; index < 8; index++ {
		out = append(out, fmt.Sprintf("%s/fixtures/image-%02d.jpg", o.emulatorURL, index))
	}
	for index := 8; index < 12; index++ {
		out = append(out, fmt.Sprintf("%s/fixtures/image-%02d.webp", o.emulatorURL, index))
	}
	for index := 12; index < 16; index++ {
		out = append(out, fmt.Sprintf("%s/fixtures/image-%02d-oversized.jpg", o.emulatorURL, index))
	}
	return out
}

func videoCombinations(images []string, count int) [][]string {
	if len(images) < 3 {
		return nil
	}
	if len(images) < 9 {
		return [][]string{append([]string(nil), images[:3]...)}
	}
	out := make([][]string, 0, count)
	seen := map[string]struct{}{}
	for seed := 0; len(out) < count; seed++ {
		imageCount := acceptanceworkload.VideoImageCount(seed)
		combo := make([]string, 0, imageCount)
		used := map[int]struct{}{}
		state := uint64(seed + 1)
		for len(combo) < imageCount {
			state = state*6364136223846793005 + 1442695040888963407
			index := int((state >> 32) % uint64(len(images)))
			if _, exists := used[index]; exists {
				continue
			}
			used[index] = struct{}{}
			combo = append(combo, images[index])
		}
		signature := strings.Join(combo, "\x00")
		if _, exists := seen[signature]; exists {
			continue
		}
		seen[signature] = struct{}{}
		out = append(out, combo)
	}
	return out
}

func streamGeminiImageHash(reader io.Reader) (int64, string, error) {
	buffered := bufio.NewReaderSize(reader, 64<<10)
	if err := scanUntil(buffered, []byte(`"inlineData"`), 256<<20); err != nil {
		return 0, "", err
	}
	if err := scanUntil(buffered, []byte(`"data"`), 1<<20); err != nil {
		return 0, "", err
	}
	for {
		item, err := buffered.ReadByte()
		if err != nil {
			return 0, "", err
		}
		if item == ':' {
			break
		}
	}
	for {
		item, err := buffered.ReadByte()
		if err != nil {
			return 0, "", err
		}
		if item == '"' {
			break
		}
		if item != ' ' && item != '\t' && item != '\r' && item != '\n' {
			return 0, "", errors.New("Gemini inlineData.data is not a JSON string")
		}
	}
	jsonString := &base64JSONStringReader{reader: buffered}
	digest := sha256.New()
	decodedBytes, err := io.Copy(digest, base64.NewDecoder(base64.StdEncoding, jsonString))
	if err != nil {
		return 0, "", fmt.Errorf("decode Gemini Base64 output: %w", err)
	}
	if decodedBytes == 0 {
		return 0, "", errors.New("Gemini Base64 output is empty")
	}
	return decodedBytes, hex.EncodeToString(digest.Sum(nil)), nil
}

type base64JSONStringReader struct {
	reader *bufio.Reader
	done   bool
}

func (r *base64JSONStringReader) Read(payload []byte) (int, error) {
	if r.done {
		return 0, io.EOF
	}
	written := 0
	for written < len(payload) {
		item, err := r.reader.ReadByte()
		if err != nil {
			return written, err
		}
		if item == '"' {
			r.done = true
			if written == 0 {
				return 0, io.EOF
			}
			return written, nil
		}
		if item == '\\' {
			return written, errors.New("escaped Base64 JSON strings are not supported")
		}
		payload[written] = item
		written++
	}
	return written, nil
}

func scanUntil(reader *bufio.Reader, target []byte, limit int64) error {
	matched := 0
	for read := int64(0); read < limit; read++ {
		item, err := reader.ReadByte()
		if err != nil {
			return err
		}
		if item == target[matched] {
			matched++
			if matched == len(target) {
				return nil
			}
			continue
		}
		if item == target[0] {
			matched = 1
		} else {
			matched = 0
		}
	}
	return errors.New("Gemini inlineData output was not found")
}

func responseStatusError(response *http.Response) error {
	defer response.Body.Close()
	payload, _ := io.ReadAll(io.LimitReader(response.Body, 512))
	return &httpStatusError{Status: response.StatusCode, Body: strings.TrimSpace(string(payload))}
}

func percentileMilliseconds(values []time.Duration, quantile float64) float64 {
	filtered := make([]time.Duration, 0, len(values))
	for _, value := range values {
		if value > 0 {
			filtered = append(filtered, value)
		}
	}
	if len(filtered) == 0 {
		return 0
	}
	sort.Slice(filtered, func(i, j int) bool { return filtered[i] < filtered[j] })
	index := int(float64(len(filtered)-1) * quantile)
	return float64(filtered[index].Microseconds()) / 1000
}

func paddedPNG(size int) []byte {
	return paddedPNGVariant(size, 0)
}

func paddedPNGVariant(size int, variant int) []byte {
	base, _ := base64.StdEncoding.DecodeString("iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNk+A8AAQUBAScY42YAAAAASUVORK5CYII=")
	if size <= len(base) {
		return base
	}
	iendOffset := len(base) - 12
	paddingLength := size - len(base) - 12
	if paddingLength < 0 {
		paddingLength = 0
	}
	chunk := make([]byte, 12+paddingLength)
	binary.BigEndian.PutUint32(chunk[:4], uint32(paddingLength))
	copy(chunk[4:8], []byte("teST"))
	if variant != 0 && paddingLength >= 8 {
		binary.BigEndian.PutUint64(chunk[8:16], uint64(variant))
	}
	binary.BigEndian.PutUint32(chunk[8+paddingLength:], crc32.ChecksumIEEE(chunk[4:8+paddingLength]))
	out := make([]byte, 0, size)
	out = append(out, base[:iendOffset]...)
	out = append(out, chunk...)
	out = append(out, base[iendOffset:]...)
	return out
}

func redactError(message string, opts options) string {
	for _, secret := range append(append([]string(nil), opts.apiKeys...), opts.runToken) {
		if secret != "" {
			message = strings.ReplaceAll(message, secret, "[REDACTED]")
		}
	}
	return reportURLPattern.ReplaceAllString(message, "[REDACTED_URL]")
}

func acceptanceRootCAs(path string) (*x509.CertPool, error) {
	if strings.TrimSpace(path) == "" {
		return nil, nil
	}
	info, err := os.Lstat(path)
	if err != nil {
		return nil, fmt.Errorf("read Gateway CA file: %w", err)
	}
	if !info.Mode().IsRegular() || info.Mode()&os.ModeSymlink != 0 {
		return nil, errors.New("Gateway CA file must be a regular non-symlink file")
	}
	payload, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read Gateway CA file: %w", err)
	}
	roots, err := x509.SystemCertPool()
	if err != nil || roots == nil {
		roots = x509.NewCertPool()
	}
	if !roots.AppendCertsFromPEM(payload) {
		return nil, errors.New("Gateway CA file does not contain a PEM certificate")
	}
	return roots, nil
}

func splitCSV(value string) []string {
	items := strings.Split(value, ",")
	out := make([]string, 0, len(items))
	for _, item := range items {
		if item = strings.TrimSpace(item); item != "" {
			out = append(out, item)
		}
	}
	return out
}

func env(name string, fallback string) string {
	if value := strings.TrimSpace(os.Getenv(name)); value != "" {
		return value
	}
	return fallback
}

func envDuration(name string, fallback time.Duration) time.Duration {
	value := strings.TrimSpace(os.Getenv(name))
	if value == "" {
		return fallback
	}
	parsed, err := time.ParseDuration(value)
	if err != nil {
		return -1
	}
	return parsed
}

func envFloat(name string, fallback float64) float64 {
	value := strings.TrimSpace(os.Getenv(name))
	if value == "" {
		return fallback
	}
	parsed, err := strconv.ParseFloat(value, 64)
	if err != nil {
		return -1
	}
	return parsed
}