package webui

import (
	"context"
	"fmt"
	"io"
	"log/slog"
	"os"
	"os/exec"
	"path/filepath"
	"runtime/debug"
	"sort"
	"strings"
	"sync"
	"syscall"
	"time"

	"bee/audit/internal/app"
	"bee/audit/internal/platform"
)

// Task statuses.
const (
	TaskPending   = "pending"
	TaskRunning   = "running"
	TaskDone      = "done"
	TaskFailed    = "failed"
	TaskCancelled = "cancelled"
)

// taskNames maps target → human-readable name for validate (SAT) runs.
var taskNames = map[string]string{
	"nvidia":                 "NVIDIA SAT",
	"nvidia-targeted-stress": "NVIDIA Targeted Stress Validate (dcgmi diag targeted_stress)",
	"nvidia-bench-perf":      "NVIDIA Bee Bench Perf",
	"nvidia-bench-power":     "NVIDIA Bee Bench Power",
	"nvidia-bench-autotune":  "NVIDIA Bee Bench Power Source Autotune",
	"nvidia-compute":         "NVIDIA Max Compute Load (dcgmproftester)",
	"nvidia-targeted-power":  "NVIDIA Targeted Power (dcgmi diag targeted_power)",
	"nvidia-pulse":           "NVIDIA Pulse Test (dcgmi diag pulse_test)",
	"nvidia-interconnect":    "NVIDIA Interconnect Test (NCCL all_reduce_perf)",
	"nvidia-bandwidth":       "NVIDIA Bandwidth Test (NVBandwidth)",
	"nvidia-stress":          "NVIDIA GPU Stress",
	"memory":                 "Memory SAT",
	"storage":                "Storage SAT",
	"tpm":                    "TPM Read-only Check",
	"nvidia-config":          "GPU Config & NVLink Check",
	"pcie-link":              "PCIe Link Check (forced retrain)",
	"nvidia-pcie-bandwidth":  "NVIDIA GPU PCIe Bandwidth Check",
	"cpu":                    "CPU SAT",
	"amd":                    "AMD GPU SAT",
	"amd-mem":                "AMD GPU MEM Integrity",
	"amd-bandwidth":          "AMD GPU MEM Bandwidth",
	"amd-stress":             "AMD GPU Burn-in",
	"memory-stress":          "Memory Burn-in",
	"sat-stress":             "SAT Stress (stressapptest)",
	"platform-stress":        "Platform Thermal Cycling",
	"audit":                  "Audit",
	"support-bundle":         "Support Bundle",
	"install":                "Install to Disk",
	"install-to-ram":         "Install to RAM",
	"nvme-format":            "NVMe Block Format Change",
}

// burnNames maps target → human-readable name when a burn profile is set.
var burnNames = map[string]string{
	"nvidia": "NVIDIA Burn-in",
	"memory": "Memory Burn-in",
	"cpu":    "CPU Burn-in",
	"amd":    "AMD GPU Burn-in",
}

func nvidiaStressTaskName(loader string) string {
	switch strings.TrimSpace(strings.ToLower(loader)) {
	case platform.NvidiaStressLoaderJohn:
		return "NVIDIA GPU Stress (John/OpenCL)"
	case platform.NvidiaStressLoaderNCCL:
		return "NVIDIA GPU Stress (NCCL)"
	default:
		return "NVIDIA GPU Stress (bee-gpu-burn)"
	}
}

func taskDisplayName(target, profile, loader string) string {
	name := taskNames[target]
	if profile != "" {
		if n, ok := burnNames[target]; ok {
			name = n
		}
	}
	if target == "nvidia-stress" {
		name = nvidiaStressTaskName(loader)
	}
	if name == "" {
		name = target
	}
	return name
}

// Task represents one unit of work in the queue.
type Task struct {
	ID             string     `json:"id"`
	Name           string     `json:"name"`
	Target         string     `json:"target"`
	Priority       int        `json:"priority"`
	Status         string     `json:"status"`
	CreatedAt      time.Time  `json:"created_at"`
	StartedAt      *time.Time `json:"started_at,omitempty"`
	DoneAt         *time.Time `json:"done_at,omitempty"`
	ElapsedSec     int        `json:"elapsed_sec,omitempty"`
	ErrMsg         string     `json:"error,omitempty"`
	LogPath        string     `json:"log_path,omitempty"`
	ArtifactsDir   string     `json:"artifacts_dir,omitempty"`
	ReportJSONPath string     `json:"report_json_path,omitempty"`
	ReportHTMLPath string     `json:"report_html_path,omitempty"`

	// runtime fields (not serialised)
	job       *jobState
	runnerPID int
	params    taskParams
}

// taskParams holds optional parameters parsed from the run request.
type taskParams struct {
	Duration            int            `json:"duration,omitempty"`
	StressMode          bool           `json:"stress_mode,omitempty"`
	GPUIndices          []int          `json:"gpu_indices,omitempty"`
	ExcludeGPUIndices   []int          `json:"exclude_gpu_indices,omitempty"`
	StaggerGPUStart     bool           `json:"stagger_gpu_start,omitempty"`
	SizeMB              int            `json:"size_mb,omitempty"`
	Passes              int            `json:"passes,omitempty"`
	Loader              string         `json:"loader,omitempty"`
	BurnProfile         string         `json:"burn_profile,omitempty"`
	BenchmarkProfile    string         `json:"benchmark_profile,omitempty"`
	BenchmarkKind       string         `json:"benchmark_kind,omitempty"`
	RunNCCL             bool           `json:"run_nccl,omitempty"`
	ParallelGPUs        bool           `json:"parallel_gpus,omitempty"`
	RampStep            int            `json:"ramp_step,omitempty"`
	RampTotal           int            `json:"ramp_total,omitempty"`
	RampRunID           string         `json:"ramp_run_id,omitempty"`
	DisplayName         string         `json:"display_name,omitempty"`
	Device              string         `json:"device,omitempty"` // for install
	LBAF                int            `json:"lbaf,omitempty"`
	PlatformComponents  []string       `json:"platform_components,omitempty"`
	SAADmiChanges       []saaChange    `json:"saa_dmi_changes,omitempty"`
	FRUChanges          []fruChange    `json:"fru_changes,omitempty"`
	HuaweiElabelChanges []huaweiChange `json:"huawei_elabel_changes,omitempty"`
	RAIDController      int            `json:"raid_controller,omitempty"`
	RAIDDevices         []string       `json:"raid_devices,omitempty"`
	RAIDArrayName       string         `json:"raid_array_name,omitempty"`
	RAIDSlot            string         `json:"raid_slot,omitempty"`
	ScenarioName        string         `json:"scenario_name,omitempty"`
}

type persistedTask struct {
	ID             string     `json:"id"`
	Name           string     `json:"name"`
	Target         string     `json:"target"`
	Priority       int        `json:"priority"`
	Status         string     `json:"status"`
	CreatedAt      time.Time  `json:"created_at"`
	StartedAt      *time.Time `json:"started_at,omitempty"`
	DoneAt         *time.Time `json:"done_at,omitempty"`
	ErrMsg         string     `json:"error,omitempty"`
	LogPath        string     `json:"log_path,omitempty"`
	ArtifactsDir   string     `json:"artifacts_dir,omitempty"`
	ReportJSONPath string     `json:"report_json_path,omitempty"`
	ReportHTMLPath string     `json:"report_html_path,omitempty"`
	Params         taskParams `json:"params,omitempty"`
}

type burnPreset struct {
	DurationSec int
}

type nvidiaRampSpec struct {
	DurationSec      int
	StaggerSeconds   int
	TotalDurationSec int
}

func resolveMemoryValidatePreset(profile string, stress bool) (sizeMB, passes int) {
	switch strings.TrimSpace(strings.ToLower(profile)) {
	case "overnight":
		return 1024, 2
	case "acceptance":
		return 1024, 1
	case "smoke":
		return 256, 1
	}
	if stress {
		return 512, 1
	}
	return 256, 1
}

func taskMayLeaveOrphanWorkers(target string) bool {
	switch strings.TrimSpace(strings.ToLower(target)) {
	case "nvidia", "nvidia-targeted-stress", "nvidia-targeted-power", "nvidia-pulse",
		"nvidia-bandwidth", "nvidia-stress", "nvidia-compute", "nvidia-bench-perf",
		"memory", "memory-stress", "cpu", "sat-stress", "platform-stress":
		return true
	default:
		return false
	}
}

func resolveBurnPreset(profile string) burnPreset {
	switch profile {
	case "overnight":
		return burnPreset{DurationSec: 8 * 60 * 60}
	case "acceptance":
		return burnPreset{DurationSec: 60 * 60}
	default:
		return burnPreset{DurationSec: 5 * 60}
	}
}

func resolveNvidiaRampPlan(profile string, enabled bool, selected []int) (nvidiaRampSpec, error) {
	base := resolveBurnPreset(profile).DurationSec
	plan := nvidiaRampSpec{
		DurationSec:      base,
		TotalDurationSec: base,
	}
	if !enabled {
		return plan, nil
	}
	count := len(selected)
	if count == 0 {
		return nvidiaRampSpec{}, fmt.Errorf("staggered NVIDIA burn requires explicit GPU selection")
	}
	if count == 1 {
		return plan, nil
	}

	switch profile {
	case "acceptance":
		plan.StaggerSeconds = 10 * 60
		plan.TotalDurationSec = plan.DurationSec + plan.StaggerSeconds*(count-1)
	case "overnight":
		plan.StaggerSeconds = 60 * 60
		plan.TotalDurationSec = 8 * 60 * 60
		minTotal := count * 60 * 60
		if plan.TotalDurationSec < minTotal {
			plan.TotalDurationSec = minTotal
		}
		if plan.TotalDurationSec > 10*60*60 {
			return nvidiaRampSpec{}, fmt.Errorf("overnight staggered NVIDIA burn supports at most 10 GPUs")
		}
		plan.DurationSec = plan.TotalDurationSec - plan.StaggerSeconds*(count-1)
	default:
		plan.StaggerSeconds = 2 * 60
		plan.TotalDurationSec = plan.DurationSec + plan.StaggerSeconds*(count-1)
	}
	return plan, nil
}

func resolvePlatformStressPreset(profile string) platform.PlatformStressOptions {
	acceptanceCycles := []platform.PlatformStressCycle{
		{LoadSec: 85, IdleSec: 5},
		{LoadSec: 80, IdleSec: 10},
		{LoadSec: 55, IdleSec: 5},
		{LoadSec: 60, IdleSec: 0},
		{LoadSec: 100, IdleSec: 10},
		{LoadSec: 145, IdleSec: 15},
		{LoadSec: 190, IdleSec: 20},
		{LoadSec: 235, IdleSec: 25},
		{LoadSec: 280, IdleSec: 30},
		{LoadSec: 325, IdleSec: 35},
		{LoadSec: 370, IdleSec: 40},
		{LoadSec: 415, IdleSec: 45},
		{LoadSec: 460, IdleSec: 50},
		{LoadSec: 510, IdleSec: 0},
	}

	switch profile {
	case "overnight":
		cycles := make([]platform.PlatformStressCycle, 0, len(acceptanceCycles)*8)
		for range 8 {
			cycles = append(cycles, acceptanceCycles...)
		}
		return platform.PlatformStressOptions{Cycles: cycles}
	case "acceptance":
		return platform.PlatformStressOptions{Cycles: acceptanceCycles}
	default: // smoke
		return platform.PlatformStressOptions{Cycles: []platform.PlatformStressCycle{
			{LoadSec: 85, IdleSec: 5},
			{LoadSec: 80, IdleSec: 10},
			{LoadSec: 55, IdleSec: 5},
			{LoadSec: 60, IdleSec: 0},
		}}
	}
}

// taskQueue manages a priority-ordered list of tasks and runs them one at a time.
type taskQueue struct {
	mu          sync.Mutex
	tasks       []*Task
	trigger     chan struct{}
	opts        *HandlerOptions // set by startWorker
	statePath   string
	logsDir     string
	started     bool
	kmsgWatcher *kmsgWatcher
}

var globalQueue = &taskQueue{trigger: make(chan struct{}, 1)}

const maxTaskHistory = 50

var (
	runMemoryAcceptancePackCtx = func(a *app.App, ctx context.Context, baseDir string, sizeMB, passes int, logFunc func(string)) (string, error) {
		return a.RunMemoryAcceptancePackCtx(ctx, baseDir, sizeMB, passes, logFunc)
	}
	runStorageAcceptancePackCtx = func(a *app.App, ctx context.Context, baseDir string, extended bool, logFunc func(string)) (string, error) {
		return a.RunStorageAcceptancePackCtx(ctx, baseDir, extended, logFunc)
	}
	runTPMValidationPackCtx = func(a *app.App, ctx context.Context, baseDir string, logFunc func(string)) (string, error) {
		return a.RunTPMValidationPackCtx(ctx, baseDir, logFunc)
	}
	runNvidiaConfigCheckPackCtx = func(a *app.App, ctx context.Context, baseDir string, logFunc func(string)) (string, error) {
		return a.RunNvidiaConfigCheckPackCtx(ctx, baseDir, logFunc)
	}
	runPCIeLinkCheckPackCtx = func(a *app.App, ctx context.Context, baseDir string, logFunc func(string)) (string, error) {
		return a.RunPCIeLinkCheckPackCtx(ctx, baseDir, logFunc)
	}
	runNvidiaPCIeBandwidthPackCtx = func(a *app.App, ctx context.Context, baseDir string, gpuIndices []int, logFunc func(string)) (string, error) {
		return a.RunNvidiaPCIeBandwidthPackCtx(ctx, baseDir, gpuIndices, logFunc)
	}
	runCPUAcceptancePackCtx = func(a *app.App, ctx context.Context, baseDir string, durationSec int, logFunc func(string)) (string, error) {
		return a.RunCPUAcceptancePackCtx(ctx, baseDir, durationSec, logFunc)
	}
	runAMDAcceptancePackCtx = func(a *app.App, ctx context.Context, baseDir string, logFunc func(string)) (string, error) {
		return a.RunAMDAcceptancePackCtx(ctx, baseDir, logFunc)
	}
	runAMDMemIntegrityPackCtx = func(a *app.App, ctx context.Context, baseDir string, logFunc func(string)) (string, error) {
		return a.RunAMDMemIntegrityPackCtx(ctx, baseDir, logFunc)
	}
	runAMDMemBandwidthPackCtx = func(a *app.App, ctx context.Context, baseDir string, logFunc func(string)) (string, error) {
		return a.RunAMDMemBandwidthPackCtx(ctx, baseDir, logFunc)
	}
	runNvidiaStressPackCtx = func(a *app.App, ctx context.Context, baseDir string, opts platform.NvidiaStressOptions, logFunc func(string)) (string, error) {
		return a.RunNvidiaStressPackCtx(ctx, baseDir, opts, logFunc)
	}
	runAMDStressPackCtx = func(a *app.App, ctx context.Context, baseDir string, durationSec int, logFunc func(string)) (string, error) {
		return a.RunAMDStressPackCtx(ctx, baseDir, durationSec, logFunc)
	}
	runMemoryStressPackCtx = func(a *app.App, ctx context.Context, baseDir string, durationSec int, logFunc func(string)) (string, error) {
		return a.RunMemoryStressPackCtx(ctx, baseDir, durationSec, logFunc)
	}
	runSATStressPackCtx = func(a *app.App, ctx context.Context, baseDir string, durationSec int, logFunc func(string)) (string, error) {
		return a.RunSATStressPackCtx(ctx, baseDir, durationSec, logFunc)
	}
	buildSupportBundle = app.BuildSupportBundle
	installCommand     = func(ctx context.Context, device string, logPath string) *exec.Cmd {
		return exec.CommandContext(ctx, "bee-install", device, logPath)
	}
	externalTaskRunnerCommand = func(exportDir, taskID string) (*exec.Cmd, error) {
		exe, err := os.Executable()
		if err != nil {
			return nil, err
		}
		return exec.Command(exe, "bee-worker", "--export-dir", exportDir, "--task-id", taskID), nil
	}
)

// enqueue adds a task to the queue and notifies the worker.
func (q *taskQueue) enqueue(t *Task) {
	q.mu.Lock()
	q.assignTaskLogPathLocked(t)
	q.tasks = append(q.tasks, t)
	q.prune()
	q.persistLocked()
	q.mu.Unlock()
	taskSerialEvent(t, "queued")
	select {
	case q.trigger <- struct{}{}:
	default:
	}
}

// prune removes oldest completed tasks beyond maxTaskHistory.
func (q *taskQueue) prune() {
	var done []*Task
	var active []*Task
	for _, t := range q.tasks {
		switch t.Status {
		case TaskDone, TaskFailed, TaskCancelled:
			done = append(done, t)
		default:
			active = append(active, t)
		}
	}
	if len(done) > maxTaskHistory {
		done = done[len(done)-maxTaskHistory:]
	}
	q.tasks = append(active, done...)
}

// nextPending returns the highest-priority pending task (nil if none).
func (q *taskQueue) nextPending() *Task {
	for _, t := range q.tasks {
		if t.Status == TaskRunning {
			return nil
		}
	}
	var best *Task
	for _, t := range q.tasks {
		if t.Status != TaskPending {
			continue
		}
		if best == nil || t.Priority > best.Priority ||
			(t.Priority == best.Priority && t.CreatedAt.Before(best.CreatedAt)) {
			best = t
		}
	}
	return best
}

// findByID looks up a task by ID.
func (q *taskQueue) findByID(id string) (*Task, bool) {
	q.mu.Lock()
	defer q.mu.Unlock()
	for _, t := range q.tasks {
		if t.ID == id {
			return t, true
		}
	}
	return nil, false
}

// findJob returns the jobState for a task ID (for SSE streaming compatibility).
func (q *taskQueue) findJob(id string) (*jobState, bool) {
	t, ok := q.findByID(id)
	if !ok || t.job == nil {
		return nil, false
	}
	return t.job, true
}

type taskStreamSource struct {
	status  string
	errMsg  string
	logPath string
	job     *jobState
}

func (q *taskQueue) taskStreamSource(id string) (taskStreamSource, bool) {
	q.mu.Lock()
	defer q.mu.Unlock()
	for _, t := range q.tasks {
		if t.ID != id {
			continue
		}
		return taskStreamSource{
			status:  t.Status,
			errMsg:  t.ErrMsg,
			logPath: t.LogPath,
			job:     t.job,
		}, true
	}
	return taskStreamSource{}, false
}

func (q *taskQueue) hasActiveTarget(target string) bool {
	q.mu.Lock()
	defer q.mu.Unlock()
	for _, t := range q.tasks {
		if t.Target != target {
			continue
		}
		if t.Status == TaskPending || t.Status == TaskRunning {
			return true
		}
	}
	return false
}

// snapshot returns a copy of all tasks sorted for display with newest tasks first.
func (q *taskQueue) snapshot() []Task {
	q.mu.Lock()
	defer q.mu.Unlock()
	out := make([]Task, len(q.tasks))
	for i, t := range q.tasks {
		out[i] = *t
		out[i].ElapsedSec = taskElapsedSec(&out[i], time.Now())
	}
	sort.SliceStable(out, func(i, j int) bool {
		if !out[i].CreatedAt.Equal(out[j].CreatedAt) {
			return out[i].CreatedAt.After(out[j].CreatedAt)
		}
		si := statusOrder(out[i].Status)
		sj := statusOrder(out[j].Status)
		if si != sj {
			return si < sj
		}
		if out[i].Priority != out[j].Priority {
			return out[i].Priority > out[j].Priority
		}
		return out[i].Name < out[j].Name
	})
	return out
}

func statusOrder(s string) int {
	switch s {
	case TaskRunning:
		return 0
	case TaskPending:
		return 1
	default:
		return 2
	}
}

// startWorker launches the queue runner goroutine.
func (q *taskQueue) startWorker(opts *HandlerOptions) {
	q.mu.Lock()
	q.opts = opts
	q.statePath = filepath.Join(opts.ExportDir, "tasks-state.json")
	q.logsDir = filepath.Join(opts.ExportDir, "tasks")
	_ = os.MkdirAll(q.logsDir, 0755)
	if !q.started {
		q.loadLocked()
		q.started = true
		q.resumeRunningTasksLocked()
		goRecoverLoop("task worker", 2*time.Second, q.worker)
	}
	hasPending := q.nextPending() != nil
	q.mu.Unlock()
	if hasPending {
		select {
		case q.trigger <- struct{}{}:
		default:
		}
	}
}

func (q *taskQueue) worker() {
	for {
		<-q.trigger
		func() {
			setCPUGovernor("performance")
			defer setCPUGovernor("powersave")

			for {
				q.mu.Lock()
				t := q.nextPending()
				if t == nil {
					q.prune()
					q.persistLocked()
					q.mu.Unlock()
					return
				}
				now := time.Now()
				t.Status = TaskRunning
				t.StartedAt = &now
				t.DoneAt = nil
				t.ErrMsg = ""
				j := newTaskJobState(t.LogPath)
				t.job = j
				q.persistLocked()
				q.mu.Unlock()

				q.runTaskExternal(t, j)

				q.mu.Lock()
				q.prune()
				q.persistLocked()
				q.mu.Unlock()
			}
		}()

	}
}

func (q *taskQueue) resumeRunningTasksLocked() {
	for _, t := range q.tasks {
		if t.Status != TaskRunning {
			continue
		}
		if t.job == nil {
			t.job = newTaskJobState(t.LogPath)
		}
		q.attachExternalTaskControlsLocked(t, t.job)
		q.startRecoveredTaskMonitorLocked(t, t.job)
	}
}

func (q *taskQueue) attachExternalTaskControlsLocked(t *Task, j *jobState) {
	if t == nil || j == nil {
		return
	}
	j.cancel = func() {
		pid := t.runnerPID
		if pid <= 0 {
			if state, ok := readTaskRunnerState(t); ok {
				pid = state.PID
			}
		}
		if pid > 0 {
			_ = syscall.Kill(pid, syscall.SIGTERM)
		}
	}
}

func (q *taskQueue) startRecoveredTaskMonitorLocked(t *Task, j *jobState) {
	if t == nil || j == nil || t.runnerPID <= 0 {
		return
	}
	goRecoverOnce("task runner monitor", func() {
		stopTail := make(chan struct{})
		doneTail := make(chan struct{})
		go q.followTaskLog(t, j, stopTail, doneTail)
		for processAlive(t.runnerPID) {
			time.Sleep(500 * time.Millisecond)
		}
		close(stopTail)
		<-doneTail
		q.finishExternalTask(t, j, nil)
	})
}

func (q *taskQueue) runTaskExternal(t *Task, j *jobState) {
	startedKmsgWatch := false
	if q.kmsgWatcher != nil && isSATTarget(t.Target) {
		q.kmsgWatcher.NotifyTaskStarted(t.ID, t.Target)
		startedKmsgWatch = true
	}
	defer func() {
		if startedKmsgWatch && q.kmsgWatcher != nil {
			q.kmsgWatcher.NotifyTaskFinished(t.ID)
		}
	}()

	stopTail := make(chan struct{})
	doneTail := make(chan struct{})
	defer func() {
		close(stopTail)
		<-doneTail
	}()
	go q.followTaskLog(t, j, stopTail, doneTail)

	cmd, err := externalTaskRunnerCommand(q.opts.ExportDir, t.ID)
	if err != nil {
		j.appendFromLog("ERROR: " + err.Error())
		q.finishExternalTask(t, j, err)
		return
	}
	if err := cmd.Start(); err != nil {
		j.appendFromLog("ERROR: " + err.Error())
		q.finishExternalTask(t, j, err)
		return
	}

	q.mu.Lock()
	t.runnerPID = cmd.Process.Pid
	q.attachExternalTaskControlsLocked(t, j)
	q.persistLocked()
	q.mu.Unlock()

	waitErr := cmd.Wait()
	time.Sleep(200 * time.Millisecond)
	q.finishExternalTask(t, j, waitErr)
}

func (q *taskQueue) followTaskLog(t *Task, j *jobState, stop <-chan struct{}, done chan<- struct{}) {
	defer close(done)
	path := ""
	if t != nil {
		path = t.LogPath
	}
	if strings.TrimSpace(path) == "" {
		return
	}
	offset := int64(0)
	if info, err := os.Stat(path); err == nil {
		offset = info.Size()
	}
	var partial string
	ticker := time.NewTicker(250 * time.Millisecond)
	defer ticker.Stop()
	flush := func() {
		data, newOffset, err := readTaskLogDelta(path, offset)
		if err != nil || len(data) == 0 {
			offset = newOffset
			return
		}
		offset = newOffset
		text := partial + strings.ReplaceAll(string(data), "\r\n", "\n")
		lines := strings.Split(text, "\n")
		partial = lines[len(lines)-1]
		for _, line := range lines[:len(lines)-1] {
			if line == "" {
				continue
			}
			j.appendFromLog(line)
		}
	}
	for {
		select {
		case <-ticker.C:
			flush()
		case <-stop:
			flush()
			if strings.TrimSpace(partial) != "" {
				j.appendFromLog(partial)
			}
			return
		}
	}
}

func readTaskLogDelta(path string, offset int64) ([]byte, int64, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, offset, err
	}
	defer f.Close()
	info, err := f.Stat()
	if err != nil {
		return nil, offset, err
	}
	if info.Size() < offset {
		offset = 0
	}
	if _, err := f.Seek(offset, io.SeekStart); err != nil {
		return nil, offset, err
	}
	data, err := io.ReadAll(io.LimitReader(f, 1<<20))
	return data, offset + int64(len(data)), err
}

func (q *taskQueue) finishExternalTask(t *Task, j *jobState, waitErr error) {
	q.mu.Lock()
	defer q.mu.Unlock()
	if t.Status == TaskDone || t.Status == TaskFailed || t.Status == TaskCancelled {
		if j != nil && !j.isDone() {
			j.finish(t.ErrMsg)
			j.closeLog()
		}
		select {
		case q.trigger <- struct{}{}:
		default:
		}
		return
	}

	state, ok := readTaskRunnerState(t)
	switch {
	case ok && state.Status != TaskRunning:
		t.Status = state.Status
		t.ErrMsg = state.Error
		now := state.UpdatedAt
		if now.IsZero() {
			now = time.Now()
		}
		t.DoneAt = &now
	case waitErr != nil:
		now := time.Now()
		t.Status = TaskFailed
		t.ErrMsg = waitErr.Error()
		t.DoneAt = &now
	default:
		now := time.Now()
		t.Status = TaskFailed
		t.ErrMsg = "task runner exited without final state"
		t.DoneAt = &now
	}
	t.runnerPID = 0
	q.finalizeTaskArtifactPathsLocked(t)
	q.persistLocked()

	if j != nil && !j.isDone() {
		j.finish(t.ErrMsg)
		j.closeLog()
	}
	if t.ErrMsg != "" {
		taskSerialEvent(t, "finished with status="+t.Status+" error="+t.ErrMsg)
	} else {
		taskSerialEvent(t, "finished with status="+t.Status)
	}
	select {
	case q.trigger <- struct{}{}:
	default:
	}
}

func (q *taskQueue) executeTask(t *Task, j *jobState, ctx context.Context) {
	startedKmsgWatch := false
	defer q.finalizeTaskRun(t, j)
	defer func() {
		if startedKmsgWatch && q.kmsgWatcher != nil {
			q.kmsgWatcher.NotifyTaskFinished(t.ID)
		}
	}()
	defer func() {
		if rec := recover(); rec != nil {
			msg := fmt.Sprintf("task panic: %v", rec)
			slog.Error("task panic",
				"task_id", t.ID,
				"target", t.Target,
				"panic", fmt.Sprint(rec),
				"stack", string(debug.Stack()),
			)
			j.append("ERROR: " + msg)
			j.finish(msg)
		}
	}()

	if q.kmsgWatcher != nil && isSATTarget(t.Target) {
		q.kmsgWatcher.NotifyTaskStarted(t.ID, t.Target)
		startedKmsgWatch = true
	}

	q.runTask(t, j, ctx)
}

func (q *taskQueue) finalizeTaskRun(t *Task, j *jobState) {
	q.mu.Lock()
	now := time.Now()
	t.DoneAt = &now
	if t.Status == TaskRunning {
		if j.err != "" {
			t.Status = TaskFailed
			t.ErrMsg = j.err
		} else {
			t.Status = TaskDone
			t.ErrMsg = ""
		}
	}
	q.finalizeTaskArtifactPathsLocked(t)
	q.persistLocked()
	q.mu.Unlock()

	if err := writeTaskReportArtifacts(t); err != nil {
		appendJobLog(t.LogPath, "WARN: task report generation failed: "+err.Error())
	}
	j.closeLog()
	if t.ErrMsg != "" {
		taskSerialEvent(t, "finished with status="+t.Status+" error="+t.ErrMsg)
		return
	}
	taskSerialEvent(t, "finished with status="+t.Status)
}

// setCPUGovernor writes the given governor to all CPU scaling_governor sysfs files.
// Silently ignores errors (e.g. when cpufreq is not available).
func setCPUGovernor(governor string) {
	matches, err := filepath.Glob("/sys/devices/system/cpu/cpu*/cpufreq/scaling_governor")
	if err != nil || len(matches) == 0 {
		return
	}
	for _, path := range matches {
		_ = os.WriteFile(path, []byte(governor), 0644)
	}
}

// runTask executes the work for a task, writing output to j. It delegates
// to executeTaskWithOptions — the exact same target dispatch the external
// task runner (RunPersistedTask, see task_runner.go) uses in its own
// subprocess — so the in-process path (recovered tasks, unit tests) and the
// subprocess path can never drift to different target coverage. Adding a new
// task target means editing one switch, not two.
func (q *taskQueue) runTask(t *Task, j *jobState, ctx context.Context) {
	executeTaskWithOptions(q.opts, t, j, ctx)
}

func splitLines(s string) []string {
	var out []string
	for _, l := range splitNL(s) {
		if l != "" {
			out = append(out, l)
		}
	}
	return out
}

func splitNL(s string) []string {
	var out []string
	start := 0
	for i, c := range s {
		if c == '\n' {
			out = append(out, s[start:i])
			start = i + 1
		}
	}
	out = append(out, s[start:])
	return out
}

// ── HTTP handlers ─────────────────────────────────────────────────────────────