package webui

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strings"
	"sync"
	"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-stress":   "NVIDIA GPU Stress",
	"memory":          "Memory SAT",
	"storage":         "Storage SAT",
	"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",
}

// 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"`

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

// taskParams holds optional parameters parsed from the run request.
type taskParams struct {
	Duration           int      `json:"duration,omitempty"`
	DiagLevel          int      `json:"diag_level,omitempty"`
	GPUIndices         []int    `json:"gpu_indices,omitempty"`
	ExcludeGPUIndices  []int    `json:"exclude_gpu_indices,omitempty"`
	Loader             string   `json:"loader,omitempty"`
	BurnProfile        string   `json:"burn_profile,omitempty"`
	DisplayName        string   `json:"display_name,omitempty"`
	Device             string   `json:"device,omitempty"` // for install
	PlatformComponents []string `json:"platform_components,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"`
	Params    taskParams `json:"params,omitempty"`
}

type burnPreset struct {
	NvidiaDiag  int
	DurationSec int
}

func resolveBurnPreset(profile string) burnPreset {
	switch profile {
	case "overnight":
		return burnPreset{NvidiaDiag: 4, DurationSec: 8 * 60 * 60}
	case "acceptance":
		return burnPreset{NvidiaDiag: 3, DurationSec: 60 * 60}
	default:
		return burnPreset{NvidiaDiag: 1, DurationSec: 5 * 60}
	}
}

func resolvePlatformStressPreset(profile string) platform.PlatformStressOptions {
	switch profile {
	case "overnight":
		return platform.PlatformStressOptions{Cycles: []platform.PlatformStressCycle{
			{LoadSec: 600, IdleSec: 120},
			{LoadSec: 600, IdleSec: 60},
			{LoadSec: 600, IdleSec: 30},
			{LoadSec: 600, IdleSec: 120},
			{LoadSec: 600, IdleSec: 60},
			{LoadSec: 600, IdleSec: 30},
			{LoadSec: 600, IdleSec: 120},
			{LoadSec: 600, IdleSec: 60},
		}}
	case "acceptance":
		return platform.PlatformStressOptions{Cycles: []platform.PlatformStressCycle{
			{LoadSec: 300, IdleSec: 60},
			{LoadSec: 300, IdleSec: 30},
			{LoadSec: 300, IdleSec: 60},
			{LoadSec: 300, IdleSec: 30},
		}}
	default: // smoke
		return platform.PlatformStressOptions{Cycles: []platform.PlatformStressCycle{
			{LoadSec: 90, IdleSec: 60},
			{LoadSec: 90, IdleSec: 30},
		}}
	}
}

// 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, logFunc func(string)) (string, error) {
		return a.RunMemoryAcceptancePackCtx(ctx, baseDir, logFunc)
	}
	runStorageAcceptancePackCtx = func(a *app.App, ctx context.Context, baseDir string, logFunc func(string)) (string, error) {
		return a.RunStorageAcceptancePackCtx(ctx, baseDir, 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)
	}
)

// 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()
	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 {
	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
		go q.worker()
	}
	hasPending := q.nextPending() != nil
	q.mu.Unlock()
	if hasPending {
		select {
		case q.trigger <- struct{}{}:
		default:
		}
	}
}

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

		// Drain all pending tasks and start them in parallel.
		q.mu.Lock()
		var batch []*Task
		for {
			t := q.nextPending()
			if t == nil {
				break
			}
			now := time.Now()
			t.Status = TaskRunning
			t.StartedAt = &now
			t.DoneAt = nil
			t.ErrMsg = ""
			j := newTaskJobState(t.LogPath)
			t.job = j
			batch = append(batch, t)
		}
		if len(batch) > 0 {
			q.persistLocked()
		}
		q.mu.Unlock()

		var wg sync.WaitGroup
		for _, t := range batch {
			t := t
			j := t.job
			taskCtx, taskCancel := context.WithCancel(context.Background())
			j.cancel = taskCancel
			wg.Add(1)
			go func() {
				defer wg.Done()

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

				q.runTask(t, j, taskCtx)

				if q.kmsgWatcher != nil {
					q.kmsgWatcher.NotifyTaskFinished(t.ID)
				}

				q.mu.Lock()
				now2 := time.Now()
				t.DoneAt = &now2
				if t.Status == TaskRunning {
					if j.err != "" {
						t.Status = TaskFailed
						t.ErrMsg = j.err
					} else {
						t.Status = TaskDone
					}
				}
				q.persistLocked()
				q.mu.Unlock()
			}()
		}
		wg.Wait()

		if len(batch) > 0 {
			q.mu.Lock()
			q.prune()
			q.persistLocked()
			q.mu.Unlock()
		}

		setCPUGovernor("powersave")
	}
}

// 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.
func (q *taskQueue) runTask(t *Task, j *jobState, ctx context.Context) {
	if q.opts == nil {
		j.append("ERROR: handler options not configured")
		j.finish("handler options not configured")
		return
	}
	a := q.opts.App

	j.append(fmt.Sprintf("Starting %s...", t.Name))
	if len(j.lines) > 0 {
		j.append(fmt.Sprintf("Recovered after bee-web restart at %s", time.Now().UTC().Format(time.RFC3339)))
	}

	var (
		archive string
		err     error
	)

	switch t.Target {
	case "nvidia":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		diagLevel := t.params.DiagLevel
		if t.params.BurnProfile != "" && diagLevel <= 0 {
			diagLevel = resolveBurnPreset(t.params.BurnProfile).NvidiaDiag
		}
		if len(t.params.GPUIndices) > 0 || diagLevel > 0 {
			result, e := a.RunNvidiaAcceptancePackWithOptions(
				ctx, "", diagLevel, t.params.GPUIndices, j.append,
			)
			if e != nil {
				err = e
			} else {
				archive = result.Body
			}
		} else {
			archive, err = a.RunNvidiaAcceptancePack("", j.append)
		}
	case "nvidia-stress":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		dur := t.params.Duration
		if t.params.BurnProfile != "" && dur <= 0 {
			dur = resolveBurnPreset(t.params.BurnProfile).DurationSec
		}
		archive, err = runNvidiaStressPackCtx(a, ctx, "", platform.NvidiaStressOptions{
			DurationSec:       dur,
			Loader:            t.params.Loader,
			GPUIndices:        t.params.GPUIndices,
			ExcludeGPUIndices: t.params.ExcludeGPUIndices,
		}, j.append)
	case "memory":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		archive, err = runMemoryAcceptancePackCtx(a, ctx, "", j.append)
	case "storage":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		archive, err = runStorageAcceptancePackCtx(a, ctx, "", j.append)
	case "cpu":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		dur := t.params.Duration
		if t.params.BurnProfile != "" && dur <= 0 {
			dur = resolveBurnPreset(t.params.BurnProfile).DurationSec
		}
		if dur <= 0 {
			dur = 60
		}
		j.append(fmt.Sprintf("CPU stress duration: %ds", dur))
		archive, err = runCPUAcceptancePackCtx(a, ctx, "", dur, j.append)
	case "amd":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		archive, err = runAMDAcceptancePackCtx(a, ctx, "", j.append)
	case "amd-mem":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		archive, err = runAMDMemIntegrityPackCtx(a, ctx, "", j.append)
	case "amd-bandwidth":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		archive, err = runAMDMemBandwidthPackCtx(a, ctx, "", j.append)
	case "amd-stress":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		dur := t.params.Duration
		if t.params.BurnProfile != "" && dur <= 0 {
			dur = resolveBurnPreset(t.params.BurnProfile).DurationSec
		}
		archive, err = runAMDStressPackCtx(a, ctx, "", dur, j.append)
	case "memory-stress":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		dur := t.params.Duration
		if t.params.BurnProfile != "" && dur <= 0 {
			dur = resolveBurnPreset(t.params.BurnProfile).DurationSec
		}
		archive, err = runMemoryStressPackCtx(a, ctx, "", dur, j.append)
	case "sat-stress":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		dur := t.params.Duration
		if t.params.BurnProfile != "" && dur <= 0 {
			dur = resolveBurnPreset(t.params.BurnProfile).DurationSec
		}
		archive, err = runSATStressPackCtx(a, ctx, "", dur, j.append)
	case "platform-stress":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		opts := resolvePlatformStressPreset(t.params.BurnProfile)
		opts.Components = t.params.PlatformComponents
		archive, err = a.RunPlatformStress(ctx, "", opts, j.append)
	case "audit":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		result, e := a.RunAuditNow(q.opts.RuntimeMode)
		if e != nil {
			err = e
		} else {
			for _, line := range splitLines(result.Body) {
				j.append(line)
			}
		}
	case "support-bundle":
		j.append("Building support bundle...")
		archive, err = buildSupportBundle(q.opts.ExportDir)
	case "install":
		if strings.TrimSpace(t.params.Device) == "" {
			err = fmt.Errorf("device is required")
			break
		}
		installLogPath := platform.InstallLogPath(t.params.Device)
		j.append("Install log: " + installLogPath)
		err = streamCmdJob(j, installCommand(ctx, t.params.Device, installLogPath))
	case "install-to-ram":
		if a == nil {
			err = fmt.Errorf("app not configured")
			break
		}
		err = a.RunInstallToRAM(ctx, j.append)
	default:
		j.append("ERROR: unknown target: " + t.Target)
		j.finish("unknown target")
		return
	}

	// If the SAT archive was produced, check overall_status and write to component DB.
	if archive != "" {
		archivePath := app.ExtractArchivePath(archive)
		if err == nil {
			if app.ReadSATOverallStatus(archivePath) == "FAILED" {
				err = fmt.Errorf("SAT overall_status=FAILED (see summary.txt)")
			}
		}
		if db := q.statusDB(); db != nil {
			app.ApplySATResultToDB(db, t.Target, archivePath)
		}
	}

	if err != nil {
		if ctx.Err() != nil {
			j.append("Aborted.")
			j.finish("aborted")
		} else {
			j.append("ERROR: " + err.Error())
			j.finish(err.Error())
		}
		return
	}
	if archive != "" {
		j.append("Archive: " + archive)
	}
	j.finish("")
}

func (q *taskQueue) statusDB() *app.ComponentStatusDB {
	if q.opts == nil || q.opts.App == nil {
		return nil
	}
	return q.opts.App.StatusDB
}

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 ─────────────────────────────────────────────────────────────

func (h *handler) handleAPITasksList(w http.ResponseWriter, _ *http.Request) {
	tasks := globalQueue.snapshot()
	writeJSON(w, tasks)
}

func (h *handler) handleAPITasksCancel(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	t, ok := globalQueue.findByID(id)
	if !ok {
		writeError(w, http.StatusNotFound, "task not found")
		return
	}
	globalQueue.mu.Lock()
	defer globalQueue.mu.Unlock()
	switch t.Status {
	case TaskPending:
		t.Status = TaskCancelled
		now := time.Now()
		t.DoneAt = &now
		globalQueue.persistLocked()
		writeJSON(w, map[string]string{"status": "cancelled"})
	case TaskRunning:
		if t.job != nil {
			t.job.abort()
		}
		t.Status = TaskCancelled
		now := time.Now()
		t.DoneAt = &now
		globalQueue.persistLocked()
		writeJSON(w, map[string]string{"status": "cancelled"})
	default:
		writeError(w, http.StatusConflict, "task is not running or pending")
	}
}

func (h *handler) handleAPITasksPriority(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	t, ok := globalQueue.findByID(id)
	if !ok {
		writeError(w, http.StatusNotFound, "task not found")
		return
	}
	var req struct {
		Delta int `json:"delta"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid body")
		return
	}
	globalQueue.mu.Lock()
	defer globalQueue.mu.Unlock()
	if t.Status != TaskPending {
		writeError(w, http.StatusConflict, "only pending tasks can be reprioritised")
		return
	}
	t.Priority += req.Delta
	globalQueue.persistLocked()
	writeJSON(w, map[string]int{"priority": t.Priority})
}

func (h *handler) handleAPITasksCancelAll(w http.ResponseWriter, _ *http.Request) {
	globalQueue.mu.Lock()
	now := time.Now()
	n := 0
	for _, t := range globalQueue.tasks {
		switch t.Status {
		case TaskPending:
			t.Status = TaskCancelled
			t.DoneAt = &now
			n++
		case TaskRunning:
			if t.job != nil {
				t.job.abort()
			}
			t.Status = TaskCancelled
			t.DoneAt = &now
			n++
		}
	}
	globalQueue.persistLocked()
	globalQueue.mu.Unlock()
	writeJSON(w, map[string]int{"cancelled": n})
}

func (h *handler) handleAPITasksKillWorkers(w http.ResponseWriter, _ *http.Request) {
	// Cancel all queued/running tasks in the queue first.
	globalQueue.mu.Lock()
	now := time.Now()
	cancelled := 0
	for _, t := range globalQueue.tasks {
		switch t.Status {
		case TaskPending:
			t.Status = TaskCancelled
			t.DoneAt = &now
			cancelled++
		case TaskRunning:
			if t.job != nil {
				t.job.abort()
			}
			t.Status = TaskCancelled
			t.DoneAt = &now
			cancelled++
		}
	}
	globalQueue.persistLocked()
	globalQueue.mu.Unlock()

	// Kill orphaned test worker processes at the OS level.
	killed := platform.KillTestWorkers()
	writeJSON(w, map[string]any{
		"cancelled": cancelled,
		"killed":    len(killed),
		"processes": killed,
	})
}

func (h *handler) handleAPITasksStream(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	src, ok := globalQueue.taskStreamSource(id)
	if !ok {
		http.Error(w, "task not found", http.StatusNotFound)
		return
	}
	if src.job != nil {
		streamJob(w, r, src.job)
		return
	}
	if src.status == TaskDone || src.status == TaskFailed || src.status == TaskCancelled {
		j := newTaskJobState(src.logPath)
		j.finish(src.errMsg)
		streamJob(w, r, j)
		return
	}
	if !sseStart(w) {
		return
	}
	sseWrite(w, "", "Task is queued. Waiting for worker...")
	ticker := time.NewTicker(200 * time.Millisecond)
	defer ticker.Stop()
	for {
		select {
		case <-ticker.C:
			src, ok = globalQueue.taskStreamSource(id)
			if !ok {
				sseWrite(w, "done", "task not found")
				return
			}
			if src.job != nil {
				streamSubscribedJob(w, r, src.job)
				return
			}
			if src.status == TaskDone || src.status == TaskFailed || src.status == TaskCancelled {
				j := newTaskJobState(src.logPath)
				j.finish(src.errMsg)
				streamSubscribedJob(w, r, j)
				return
			}
		case <-r.Context().Done():
			return
		}
	}
}

func (q *taskQueue) assignTaskLogPathLocked(t *Task) {
	if t.LogPath != "" || q.logsDir == "" || t.ID == "" {
		return
	}
	t.LogPath = filepath.Join(q.logsDir, t.ID+".log")
}

func (q *taskQueue) loadLocked() {
	if q.statePath == "" {
		return
	}
	data, err := os.ReadFile(q.statePath)
	if err != nil || len(data) == 0 {
		return
	}
	var persisted []persistedTask
	if err := json.Unmarshal(data, &persisted); err != nil {
		return
	}
	for _, pt := range persisted {
		t := &Task{
			ID:        pt.ID,
			Name:      pt.Name,
			Target:    pt.Target,
			Priority:  pt.Priority,
			Status:    pt.Status,
			CreatedAt: pt.CreatedAt,
			StartedAt: pt.StartedAt,
			DoneAt:    pt.DoneAt,
			ErrMsg:    pt.ErrMsg,
			LogPath:   pt.LogPath,
			params:    pt.Params,
		}
		q.assignTaskLogPathLocked(t)
		if t.Status == TaskRunning {
			// The task was interrupted by a bee-web restart. Child processes
			// (e.g. bee-gpu-burn-worker) survive the restart in their own
			// process groups and cannot be cancelled retroactively. Mark the
			// task as failed so the user can decide whether to re-run it
			// rather than blindly re-launching duplicate workers.
			now := time.Now()
			t.Status = TaskFailed
			t.DoneAt = &now
			t.ErrMsg = "interrupted by bee-web restart"
		} else if t.Status == TaskPending {
			t.StartedAt = nil
			t.DoneAt = nil
			t.ErrMsg = ""
		}
		q.tasks = append(q.tasks, t)
	}
	q.prune()
	q.persistLocked()
}

func (q *taskQueue) persistLocked() {
	if q.statePath == "" {
		return
	}
	state := make([]persistedTask, 0, len(q.tasks))
	for _, t := range q.tasks {
		state = append(state, persistedTask{
			ID:        t.ID,
			Name:      t.Name,
			Target:    t.Target,
			Priority:  t.Priority,
			Status:    t.Status,
			CreatedAt: t.CreatedAt,
			StartedAt: t.StartedAt,
			DoneAt:    t.DoneAt,
			ErrMsg:    t.ErrMsg,
			LogPath:   t.LogPath,
			Params:    t.params,
		})
	}
	data, err := json.MarshalIndent(state, "", "  ")
	if err != nil {
		return
	}
	tmp := q.statePath + ".tmp"
	if err := os.WriteFile(tmp, data, 0644); err != nil {
		return
	}
	_ = os.Rename(tmp, q.statePath)
}

func taskElapsedSec(t *Task, now time.Time) int {
	if t == nil || t.StartedAt == nil || t.StartedAt.IsZero() {
		return 0
	}
	start := *t.StartedAt
	if !t.CreatedAt.IsZero() && start.Before(t.CreatedAt) {
		start = t.CreatedAt
	}
	end := now
	if t.DoneAt != nil && !t.DoneAt.IsZero() {
		end = *t.DoneAt
	}
	if end.Before(start) {
		return 0
	}
	return int(end.Sub(start).Round(time.Second) / time.Second)
}