package webui

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os/exec"
	"path/filepath"
	"strings"
	"sync/atomic"
	"time"

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

// ── Job ID counter ────────────────────────────────────────────────────────────

var jobCounter atomic.Uint64

func newJobID(prefix string) string {
	return fmt.Sprintf("%s-%d", prefix, jobCounter.Add(1))
}

// ── SSE helpers ───────────────────────────────────────────────────────────────

func sseWrite(w http.ResponseWriter, event, data string) bool {
	f, ok := w.(http.Flusher)
	if !ok {
		return false
	}
	if event != "" {
		fmt.Fprintf(w, "event: %s\n", event)
	}
	fmt.Fprintf(w, "data: %s\n\n", data)
	f.Flush()
	return true
}

func sseStart(w http.ResponseWriter) bool {
	_, ok := w.(http.Flusher)
	if !ok {
		http.Error(w, "streaming not supported", http.StatusInternalServerError)
		return false
	}
	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")
	w.Header().Set("Access-Control-Allow-Origin", "*")
	return true
}

// streamJob streams lines from a jobState to a SSE response.
func streamJob(w http.ResponseWriter, r *http.Request, j *jobState) {
	if !sseStart(w) {
		return
	}
	existing, ch := j.subscribe()
	for _, line := range existing {
		sseWrite(w, "", line)
	}
	if ch == nil {
		// Job already finished
		sseWrite(w, "done", j.err)
		return
	}
	for {
		select {
		case line, ok := <-ch:
			if !ok {
				sseWrite(w, "done", j.err)
				return
			}
			sseWrite(w, "", line)
		case <-r.Context().Done():
			return
		}
	}
}

// runCmdJob runs an exec.Cmd as a background job, streaming stdout+stderr lines.
func runCmdJob(j *jobState, cmd *exec.Cmd) {
	pr, pw := io.Pipe()
	cmd.Stdout = pw
	cmd.Stderr = pw

	if err := cmd.Start(); err != nil {
		j.finish(err.Error())
		return
	}

	go func() {
		scanner := bufio.NewScanner(pr)
		for scanner.Scan() {
			j.append(scanner.Text())
		}
	}()

	err := cmd.Wait()
	_ = pw.Close()
	if err != nil {
		j.finish(err.Error())
	} else {
		j.finish("")
	}
}

// ── Audit ─────────────────────────────────────────────────────────────────────

func (h *handler) handleAPIAuditRun(w http.ResponseWriter, r *http.Request) {
	if h.opts.App == nil {
		writeError(w, http.StatusServiceUnavailable, "app not configured")
		return
	}
	id := newJobID("audit")
	j := globalJobs.create(id)
	go func() {
		j.append("Running audit...")
		result, err := h.opts.App.RunAuditNow(h.opts.RuntimeMode)
		if err != nil {
			j.append("ERROR: " + err.Error())
			j.finish(err.Error())
			return
		}
		for _, line := range strings.Split(result.Body, "\n") {
			if line != "" {
				j.append(line)
			}
		}
		j.finish("")
	}()
	writeJSON(w, map[string]string{"job_id": id})
}

func (h *handler) handleAPIAuditStream(w http.ResponseWriter, r *http.Request) {
	id := r.URL.Query().Get("job_id")
	j, ok := globalJobs.get(id)
	if !ok {
		http.Error(w, "job not found", http.StatusNotFound)
		return
	}
	streamJob(w, r, j)
}

// ── SAT ───────────────────────────────────────────────────────────────────────

func (h *handler) handleAPISATRun(target string) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if h.opts.App == nil {
			writeError(w, http.StatusServiceUnavailable, "app not configured")
			return
		}
		id := newJobID("sat-" + target)
		j := globalJobs.create(id)

		go func() {
			j.append(fmt.Sprintf("Starting %s acceptance test...", target))
			var (
				archive string
				err     error
			)

			// Parse optional parameters
			var body struct {
				Duration   int   `json:"duration"`
				DiagLevel  int   `json:"diag_level"`
				GPUIndices []int `json:"gpu_indices"`
			}
			body.DiagLevel = 1
			if r.ContentLength > 0 {
				_ = json.NewDecoder(r.Body).Decode(&body)
			}

			switch target {
			case "nvidia":
				if len(body.GPUIndices) > 0 || body.DiagLevel > 0 {
					result, e := h.opts.App.RunNvidiaAcceptancePackWithOptions(
						context.Background(), "", body.DiagLevel, body.GPUIndices,
					)
					if e != nil {
						err = e
					} else {
						archive = result.Body
					}
				} else {
					archive, err = h.opts.App.RunNvidiaAcceptancePack("")
				}
			case "memory":
				archive, err = h.opts.App.RunMemoryAcceptancePack("")
			case "storage":
				archive, err = h.opts.App.RunStorageAcceptancePack("")
			case "cpu":
				dur := body.Duration
				if dur <= 0 {
					dur = 60
				}
				archive, err = h.opts.App.RunCPUAcceptancePack("", dur)
			}

			if err != nil {
				j.append("ERROR: " + err.Error())
				j.finish(err.Error())
				return
			}
			j.append(fmt.Sprintf("Archive written: %s", archive))
			j.finish("")
		}()

		writeJSON(w, map[string]string{"job_id": id})
	}
}

func (h *handler) handleAPISATStream(w http.ResponseWriter, r *http.Request) {
	id := r.URL.Query().Get("job_id")
	j, ok := globalJobs.get(id)
	if !ok {
		http.Error(w, "job not found", http.StatusNotFound)
		return
	}
	streamJob(w, r, j)
}

// ── Services ──────────────────────────────────────────────────────────────────

func (h *handler) handleAPIServicesList(w http.ResponseWriter, r *http.Request) {
	if h.opts.App == nil {
		writeError(w, http.StatusServiceUnavailable, "app not configured")
		return
	}
	names, err := h.opts.App.ListBeeServices()
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	type serviceInfo struct {
		Name  string `json:"name"`
		State string `json:"state"`
		Body  string `json:"body"`
	}
	result := make([]serviceInfo, 0, len(names))
	for _, name := range names {
		state := h.opts.App.ServiceState(name)
		body, _ := h.opts.App.ServiceStatus(name)
		result = append(result, serviceInfo{Name: name, State: state, Body: body})
	}
	writeJSON(w, result)
}

func (h *handler) handleAPIServicesAction(w http.ResponseWriter, r *http.Request) {
	if h.opts.App == nil {
		writeError(w, http.StatusServiceUnavailable, "app not configured")
		return
	}
	var req struct {
		Name   string `json:"name"`
		Action string `json:"action"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	var action platform.ServiceAction
	switch req.Action {
	case "start":
		action = platform.ServiceStart
	case "stop":
		action = platform.ServiceStop
	case "restart":
		action = platform.ServiceRestart
	default:
		writeError(w, http.StatusBadRequest, "action must be start|stop|restart")
		return
	}
	result, err := h.opts.App.ServiceActionResult(req.Name, action)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, map[string]string{"status": "ok", "output": result.Body})
}

// ── Network ───────────────────────────────────────────────────────────────────

func (h *handler) handleAPINetworkStatus(w http.ResponseWriter, r *http.Request) {
	if h.opts.App == nil {
		writeError(w, http.StatusServiceUnavailable, "app not configured")
		return
	}
	ifaces, err := h.opts.App.ListInterfaces()
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, map[string]any{
		"interfaces":    ifaces,
		"default_route": h.opts.App.DefaultRoute(),
	})
}

func (h *handler) handleAPINetworkDHCP(w http.ResponseWriter, r *http.Request) {
	if h.opts.App == nil {
		writeError(w, http.StatusServiceUnavailable, "app not configured")
		return
	}
	var req struct {
		Interface string `json:"interface"`
	}
	_ = json.NewDecoder(r.Body).Decode(&req)

	var result app.ActionResult
	var err error
	if req.Interface == "" || req.Interface == "all" {
		result, err = h.opts.App.DHCPAllResult()
	} else {
		result, err = h.opts.App.DHCPOneResult(req.Interface)
	}
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, map[string]string{"status": "ok", "output": result.Body})
}

func (h *handler) handleAPINetworkStatic(w http.ResponseWriter, r *http.Request) {
	if h.opts.App == nil {
		writeError(w, http.StatusServiceUnavailable, "app not configured")
		return
	}
	var req struct {
		Interface string   `json:"interface"`
		Address   string   `json:"address"`
		Prefix    string   `json:"prefix"`
		Gateway   string   `json:"gateway"`
		DNS       []string `json:"dns"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	cfg := platform.StaticIPv4Config{
		Interface: req.Interface,
		Address:   req.Address,
		Prefix:    req.Prefix,
		Gateway:   req.Gateway,
		DNS:       req.DNS,
	}
	result, err := h.opts.App.SetStaticIPv4Result(cfg)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, map[string]string{"status": "ok", "output": result.Body})
}

// ── Export ────────────────────────────────────────────────────────────────────

func (h *handler) handleAPIExportList(w http.ResponseWriter, r *http.Request) {
	entries, err := listExportFiles(h.opts.ExportDir)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, entries)
}

func (h *handler) handleAPIExportBundle(w http.ResponseWriter, r *http.Request) {
	archive, err := app.BuildSupportBundle(h.opts.ExportDir)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, map[string]string{
		"status": "ok",
		"path":   archive,
		"url":    "/export/support.tar.gz",
	})
}

// ── Tools ─────────────────────────────────────────────────────────────────────

var standardTools = []string{
	"dmidecode", "smartctl", "nvme", "lspci", "ipmitool",
	"nvidia-smi", "memtester", "stress-ng", "nvtop",
	"mstflint", "qrencode",
}

func (h *handler) handleAPIToolsCheck(w http.ResponseWriter, r *http.Request) {
	if h.opts.App == nil {
		writeError(w, http.StatusServiceUnavailable, "app not configured")
		return
	}
	statuses := h.opts.App.CheckTools(standardTools)
	writeJSON(w, statuses)
}

// ── Preflight ─────────────────────────────────────────────────────────────────

func (h *handler) handleAPIPreflight(w http.ResponseWriter, r *http.Request) {
	data, err := loadSnapshot(filepath.Join(h.opts.ExportDir, "runtime-health.json"))
	if err != nil {
		writeError(w, http.StatusNotFound, "runtime health not found")
		return
	}
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.Header().Set("Cache-Control", "no-store")
	_, _ = w.Write(data)
}

// ── Metrics SSE ───────────────────────────────────────────────────────────────

func (h *handler) handleAPIMetricsStream(w http.ResponseWriter, r *http.Request) {
	if !sseStart(w) {
		return
	}
	ticker := time.NewTicker(time.Second)
	defer ticker.Stop()
	for {
		select {
		case <-r.Context().Done():
			return
		case <-ticker.C:
			sample := platform.SampleLiveMetrics()
			b, err := json.Marshal(sample)
			if err != nil {
				continue
			}
			if !sseWrite(w, "metrics", string(b)) {
				return
			}
		}
	}
}