package platform

import (
	"archive/tar"
	"compress/gzip"
	"context"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"time"
)

// NvidiaGPU holds basic GPU info from nvidia-smi.
type NvidiaGPU struct {
	Index    int
	Name     string
	MemoryMB int
}

// ListNvidiaGPUs returns GPUs visible to nvidia-smi.
func (s *System) ListNvidiaGPUs() ([]NvidiaGPU, error) {
	out, err := exec.Command("nvidia-smi",
		"--query-gpu=index,name,memory.total",
		"--format=csv,noheader,nounits").Output()
	if err != nil {
		return nil, fmt.Errorf("nvidia-smi: %w", err)
	}
	var gpus []NvidiaGPU
	for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}
		parts := strings.SplitN(line, ", ", 3)
		if len(parts) != 3 {
			continue
		}
		idx, err := strconv.Atoi(strings.TrimSpace(parts[0]))
		if err != nil {
			continue
		}
		memMB, _ := strconv.Atoi(strings.TrimSpace(parts[2]))
		gpus = append(gpus, NvidiaGPU{
			Index:    idx,
			Name:     strings.TrimSpace(parts[1]),
			MemoryMB: memMB,
		})
	}
	return gpus, nil
}

func (s *System) RunNvidiaAcceptancePack(baseDir string) (string, error) {
	return runAcceptancePack(baseDir, "gpu-nvidia", nvidiaSATJobs())
}

// RunNvidiaAcceptancePackWithOptions runs the NVIDIA SAT with explicit duration,
// GPU memory size, and GPU index selection. ctx cancellation kills the running job.
func (s *System) RunNvidiaAcceptancePackWithOptions(ctx context.Context, baseDir string, durationSec int, sizeMB int, gpuIndices []int) (string, error) {
	return runAcceptancePackCtx(ctx, baseDir, "gpu-nvidia", nvidiaSATJobsWithOptions(durationSec, sizeMB, gpuIndices))
}

func (s *System) RunMemoryAcceptancePack(baseDir string) (string, error) {
	sizeMB := envInt("BEE_MEMTESTER_SIZE_MB", 128)
	passes := envInt("BEE_MEMTESTER_PASSES", 1)
	return runAcceptancePack(baseDir, "memory", []satJob{
		{name: "01-free-before.log", cmd: []string{"free", "-h"}},
		{name: "02-memtester.log", cmd: []string{"memtester", fmt.Sprintf("%dM", sizeMB), fmt.Sprintf("%d", passes)}},
		{name: "03-free-after.log", cmd: []string{"free", "-h"}},
	})
}

func (s *System) RunCPUAcceptancePack(baseDir string, durationSec int) (string, error) {
	if durationSec <= 0 {
		durationSec = 60
	}
	return runAcceptancePack(baseDir, "cpu", []satJob{
		{name: "01-lscpu.log", cmd: []string{"lscpu"}},
		{name: "02-sensors-before.log", cmd: []string{"sensors"}},
		{name: "03-stress-ng.log", cmd: []string{"stress-ng", "--cpu", "0", "--cpu-method", "all", "--timeout", fmt.Sprintf("%d", durationSec)}},
		{name: "04-sensors-after.log", cmd: []string{"sensors"}},
	})
}

func (s *System) RunStorageAcceptancePack(baseDir string) (string, error) {
	if baseDir == "" {
		baseDir = "/var/log/bee-sat"
	}
	ts := time.Now().UTC().Format("20060102-150405")
	runDir := filepath.Join(baseDir, "storage-"+ts)
	if err := os.MkdirAll(runDir, 0755); err != nil {
		return "", err
	}
	verboseLog := filepath.Join(runDir, "verbose.log")

	devices, err := listStorageDevices()
	if err != nil {
		return "", err
	}
	sort.Strings(devices)

	var summary strings.Builder
	stats := satStats{}
	fmt.Fprintf(&summary, "run_at_utc=%s\n", time.Now().UTC().Format(time.RFC3339))
	if len(devices) == 0 {
		fmt.Fprintln(&summary, "devices=0")
		stats.Unsupported++
	} else {
		fmt.Fprintf(&summary, "devices=%d\n", len(devices))
	}

	for index, devPath := range devices {
		prefix := fmt.Sprintf("%02d-%s", index+1, filepath.Base(devPath))
		commands := storageSATCommands(devPath)
		for cmdIndex, job := range commands {
			name := fmt.Sprintf("%s-%02d-%s.log", prefix, cmdIndex+1, job.name)
			out, err := runSATCommand(verboseLog, job.name, job.cmd)
			if writeErr := os.WriteFile(filepath.Join(runDir, name), out, 0644); writeErr != nil {
				return "", writeErr
			}
			status, rc := classifySATResult(job.name, out, err)
			stats.Add(status)
			key := filepath.Base(devPath) + "_" + strings.ReplaceAll(job.name, "-", "_")
			fmt.Fprintf(&summary, "%s_rc=%d\n", key, rc)
			fmt.Fprintf(&summary, "%s_status=%s\n", key, status)
		}
	}

	writeSATStats(&summary, stats)
	if err := os.WriteFile(filepath.Join(runDir, "summary.txt"), []byte(summary.String()), 0644); err != nil {
		return "", err
	}
	archive := filepath.Join(baseDir, "storage-"+ts+".tar.gz")
	if err := createTarGz(archive, runDir); err != nil {
		return "", err
	}
	return archive, nil
}

type satJob struct {
	name       string
	cmd        []string
	env        []string // extra env vars (appended to os.Environ)
	collectGPU bool     // collect GPU metrics via nvidia-smi while this job runs
	gpuIndices []int    // GPU indices to collect metrics for (empty = all)
}

type satStats struct {
	OK          int
	Failed      int
	Unsupported int
}

func nvidiaSATJobs() []satJob {
	seconds := envInt("BEE_GPU_STRESS_SECONDS", 5)
	sizeMB := envInt("BEE_GPU_STRESS_SIZE_MB", 64)
	return []satJob{
		{name: "01-nvidia-smi-q.log", cmd: []string{"nvidia-smi", "-q"}},
		{name: "02-dmidecode-baseboard.log", cmd: []string{"dmidecode", "-t", "baseboard"}},
		{name: "03-dmidecode-system.log", cmd: []string{"dmidecode", "-t", "system"}},
		{name: "04-nvidia-bug-report.log", cmd: []string{"nvidia-bug-report.sh", "--output-file", "{{run_dir}}/nvidia-bug-report.log"}},
		{name: "05-bee-gpu-stress.log", cmd: []string{"bee-gpu-stress", "--seconds", fmt.Sprintf("%d", seconds), "--size-mb", fmt.Sprintf("%d", sizeMB)}},
	}
}

func runAcceptancePack(baseDir, prefix string, jobs []satJob) (string, error) {
	if baseDir == "" {
		baseDir = "/var/log/bee-sat"
	}
	ts := time.Now().UTC().Format("20060102-150405")
	runDir := filepath.Join(baseDir, prefix+"-"+ts)
	if err := os.MkdirAll(runDir, 0755); err != nil {
		return "", err
	}
	verboseLog := filepath.Join(runDir, "verbose.log")

	var summary strings.Builder
	stats := satStats{}
	fmt.Fprintf(&summary, "run_at_utc=%s\n", time.Now().UTC().Format(time.RFC3339))
	for _, job := range jobs {
		cmd := make([]string, 0, len(job.cmd))
		for _, arg := range job.cmd {
			cmd = append(cmd, strings.ReplaceAll(arg, "{{run_dir}}", runDir))
		}
		out, err := runSATCommand(verboseLog, job.name, cmd)
		if writeErr := os.WriteFile(filepath.Join(runDir, job.name), out, 0644); writeErr != nil {
			return "", writeErr
		}
		status, rc := classifySATResult(job.name, out, err)
		stats.Add(status)
		key := strings.TrimSuffix(strings.TrimPrefix(job.name, "0"), ".log")
		fmt.Fprintf(&summary, "%s_rc=%d\n", key, rc)
		fmt.Fprintf(&summary, "%s_status=%s\n", key, status)
	}
	writeSATStats(&summary, stats)
	if err := os.WriteFile(filepath.Join(runDir, "summary.txt"), []byte(summary.String()), 0644); err != nil {
		return "", err
	}

	archive := filepath.Join(baseDir, prefix+"-"+ts+".tar.gz")
	if err := createTarGz(archive, runDir); err != nil {
		return "", err
	}
	return archive, nil
}

func nvidiaSATJobsWithOptions(durationSec, sizeMB int, gpuIndices []int) []satJob {
	var env []string
	if len(gpuIndices) > 0 {
		ids := make([]string, len(gpuIndices))
		for i, idx := range gpuIndices {
			ids[i] = strconv.Itoa(idx)
		}
		env = []string{"CUDA_VISIBLE_DEVICES=" + strings.Join(ids, ",")}
	}
	return []satJob{
		{name: "01-nvidia-smi-q.log", cmd: []string{"nvidia-smi", "-q"}},
		{name: "02-dmidecode-baseboard.log", cmd: []string{"dmidecode", "-t", "baseboard"}},
		{name: "03-dmidecode-system.log", cmd: []string{"dmidecode", "-t", "system"}},
		{name: "04-nvidia-bug-report.log", cmd: []string{"nvidia-bug-report.sh", "--output-file", "{{run_dir}}/nvidia-bug-report.log"}},
		{
			name:       "05-bee-gpu-stress.log",
			cmd:        []string{"bee-gpu-stress", "--seconds", strconv.Itoa(durationSec), "--size-mb", strconv.Itoa(sizeMB)},
			env:        env,
			collectGPU: true,
			gpuIndices: gpuIndices,
		},
	}
}

func runAcceptancePackCtx(ctx context.Context, baseDir, prefix string, jobs []satJob) (string, error) {
	if baseDir == "" {
		baseDir = "/var/log/bee-sat"
	}
	ts := time.Now().UTC().Format("20060102-150405")
	runDir := filepath.Join(baseDir, prefix+"-"+ts)
	if err := os.MkdirAll(runDir, 0755); err != nil {
		return "", err
	}
	verboseLog := filepath.Join(runDir, "verbose.log")

	var summary strings.Builder
	stats := satStats{}
	fmt.Fprintf(&summary, "run_at_utc=%s\n", time.Now().UTC().Format(time.RFC3339))
	for _, job := range jobs {
		if ctx.Err() != nil {
			break
		}
		cmd := make([]string, 0, len(job.cmd))
		for _, arg := range job.cmd {
			cmd = append(cmd, strings.ReplaceAll(arg, "{{run_dir}}", runDir))
		}

		var out []byte
		var err error

		if job.collectGPU {
			out, err = runSATCommandWithMetrics(ctx, verboseLog, job.name, cmd, job.env, job.gpuIndices, runDir)
		} else {
			out, err = runSATCommandCtx(ctx, verboseLog, job.name, cmd, job.env)
		}

		if writeErr := os.WriteFile(filepath.Join(runDir, job.name), out, 0644); writeErr != nil {
			return "", writeErr
		}
		status, rc := classifySATResult(job.name, out, err)
		stats.Add(status)
		key := strings.TrimSuffix(strings.TrimPrefix(job.name, "0"), ".log")
		fmt.Fprintf(&summary, "%s_rc=%d\n", key, rc)
		fmt.Fprintf(&summary, "%s_status=%s\n", key, status)
	}
	writeSATStats(&summary, stats)
	if err := os.WriteFile(filepath.Join(runDir, "summary.txt"), []byte(summary.String()), 0644); err != nil {
		return "", err
	}

	archive := filepath.Join(baseDir, prefix+"-"+ts+".tar.gz")
	if err := createTarGz(archive, runDir); err != nil {
		return "", err
	}
	return archive, nil
}

func runSATCommandCtx(ctx context.Context, verboseLog, name string, cmd []string, env []string) ([]byte, error) {
	start := time.Now().UTC()
	appendSATVerboseLog(verboseLog,
		fmt.Sprintf("[%s] start %s", start.Format(time.RFC3339), name),
		"cmd: "+strings.Join(cmd, " "),
	)

	c := exec.CommandContext(ctx, cmd[0], cmd[1:]...)
	if len(env) > 0 {
		c.Env = append(os.Environ(), env...)
	}
	out, err := c.CombinedOutput()

	rc := 0
	if err != nil {
		rc = 1
	}
	appendSATVerboseLog(verboseLog,
		fmt.Sprintf("[%s] finish %s", time.Now().UTC().Format(time.RFC3339), name),
		fmt.Sprintf("rc: %d", rc),
		fmt.Sprintf("duration_ms: %d", time.Since(start).Milliseconds()),
		"",
	)
	return out, err
}

func listStorageDevices() ([]string, error) {
	out, err := exec.Command("lsblk", "-dn", "-o", "NAME,TYPE").Output()
	if err != nil {
		return nil, err
	}
	var devices []string
	for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
		fields := strings.Fields(strings.TrimSpace(line))
		if len(fields) != 2 || fields[1] != "disk" {
			continue
		}
		devices = append(devices, "/dev/"+fields[0])
	}
	return devices, nil
}

func storageSATCommands(devPath string) []satJob {
	if strings.Contains(filepath.Base(devPath), "nvme") {
		return []satJob{
			{name: "nvme-id-ctrl", cmd: []string{"nvme", "id-ctrl", devPath, "-o", "json"}},
			{name: "nvme-smart-log", cmd: []string{"nvme", "smart-log", devPath, "-o", "json"}},
			{name: "nvme-device-self-test", cmd: []string{"nvme", "device-self-test", devPath, "-s", "1", "--wait"}},
		}
	}
	return []satJob{
		{name: "smartctl-health", cmd: []string{"smartctl", "-H", "-A", devPath}},
		{name: "smartctl-self-test-short", cmd: []string{"smartctl", "-t", "short", devPath}},
	}
}

func (s *satStats) Add(status string) {
	switch status {
	case "OK":
		s.OK++
	case "UNSUPPORTED":
		s.Unsupported++
	default:
		s.Failed++
	}
}

func (s satStats) Overall() string {
	if s.Failed > 0 {
		return "FAILED"
	}
	if s.Unsupported > 0 {
		return "PARTIAL"
	}
	return "OK"
}

func writeSATStats(summary *strings.Builder, stats satStats) {
	fmt.Fprintf(summary, "overall_status=%s\n", stats.Overall())
	fmt.Fprintf(summary, "job_ok=%d\n", stats.OK)
	fmt.Fprintf(summary, "job_failed=%d\n", stats.Failed)
	fmt.Fprintf(summary, "job_unsupported=%d\n", stats.Unsupported)
}

func classifySATResult(name string, out []byte, err error) (string, int) {
	rc := 0
	if err != nil {
		rc = 1
	}
	if err == nil {
		return "OK", rc
	}

	text := strings.ToLower(string(out))
	if strings.Contains(text, "unsupported") ||
		strings.Contains(text, "not supported") ||
		strings.Contains(text, "invalid opcode") ||
		strings.Contains(text, "unknown command") ||
		strings.Contains(text, "not implemented") ||
		strings.Contains(text, "not available") ||
		strings.Contains(text, "cuda_error_system_not_ready") ||
		strings.Contains(text, "no such device") ||
		(strings.Contains(name, "self-test") && strings.Contains(text, "aborted")) {
		return "UNSUPPORTED", rc
	}
	return "FAILED", rc
}

func runSATCommand(verboseLog, name string, cmd []string) ([]byte, error) {
	start := time.Now().UTC()
	appendSATVerboseLog(verboseLog,
		fmt.Sprintf("[%s] start %s", start.Format(time.RFC3339), name),
		"cmd: "+strings.Join(cmd, " "),
	)

	out, err := exec.Command(cmd[0], cmd[1:]...).CombinedOutput()

	rc := 0
	if err != nil {
		rc = 1
	}
	appendSATVerboseLog(verboseLog,
		fmt.Sprintf("[%s] finish %s", time.Now().UTC().Format(time.RFC3339), name),
		fmt.Sprintf("rc: %d", rc),
		fmt.Sprintf("duration_ms: %d", time.Since(start).Milliseconds()),
		"",
	)
	return out, err
}

// runSATCommandWithMetrics runs a command while collecting GPU metrics in the background.
// On completion it writes gpu-metrics.csv and gpu-metrics.html into runDir.
func runSATCommandWithMetrics(ctx context.Context, verboseLog, name string, cmd []string, env []string, gpuIndices []int, runDir string) ([]byte, error) {
	stopCh := make(chan struct{})
	doneCh := make(chan struct{})
	var metricRows []GPUMetricRow
	start := time.Now()

	go func() {
		defer close(doneCh)
		ticker := time.NewTicker(time.Second)
		defer ticker.Stop()
		for {
			select {
			case <-stopCh:
				return
			case <-ticker.C:
				samples, err := sampleGPUMetrics(gpuIndices)
				if err != nil {
					continue
				}
				elapsed := time.Since(start).Seconds()
				for i := range samples {
					samples[i].ElapsedSec = elapsed
				}
				metricRows = append(metricRows, samples...)
			}
		}
	}()

	out, err := runSATCommandCtx(ctx, verboseLog, name, cmd, env)

	close(stopCh)
	<-doneCh

	if len(metricRows) > 0 {
		_ = WriteGPUMetricsCSV(filepath.Join(runDir, "gpu-metrics.csv"), metricRows)
		_ = WriteGPUMetricsHTML(filepath.Join(runDir, "gpu-metrics.html"), metricRows)
		chart := RenderGPUTerminalChart(metricRows)
		_ = os.WriteFile(filepath.Join(runDir, "gpu-metrics-term.txt"), []byte(chart), 0644)
	}

	return out, err
}

func appendSATVerboseLog(path string, lines ...string) {
	if path == "" {
		return
	}
	f, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
	if err != nil {
		return
	}
	defer f.Close()
	for _, line := range lines {
		_, _ = io.WriteString(f, line+"\n")
	}
}

func envInt(name string, fallback int) int {
	raw := strings.TrimSpace(os.Getenv(name))
	if raw == "" {
		return fallback
	}
	value, err := strconv.Atoi(raw)
	if err != nil || value <= 0 {
		return fallback
	}
	return value
}

func createTarGz(dst, srcDir string) error {
	file, err := os.Create(dst)
	if err != nil {
		return err
	}
	defer file.Close()

	gz := gzip.NewWriter(file)
	defer gz.Close()

	tw := tar.NewWriter(gz)
	defer tw.Close()

	base := filepath.Dir(srcDir)
	return filepath.Walk(srcDir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() {
			return nil
		}
		header, err := tar.FileInfoHeader(info, "")
		if err != nil {
			return err
		}
		rel, err := filepath.Rel(base, path)
		if err != nil {
			return err
		}
		header.Name = rel
		if err := tw.WriteHeader(header); err != nil {
			return err
		}
		file, err := os.Open(path)
		if err != nil {
			return err
		}
		defer file.Close()
		_, err = io.Copy(tw, file)
		return err
	})
}