package web

import (
	"encoding/json"
	"html/template"
	"log"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"nasmon/internal/collect"
	"nasmon/internal/config"
	"nasmon/internal/sched"
	"nasmon/internal/store"
	"nasmon/internal/zfsadm"
)

type dashVM struct {
	S         sched.Status
	Th        config.Thresholds
	CPUSpark  template.HTML
	MemSpark  template.HTML
	TempSpark template.HTML
	MemPct    float64
	ARCPct    float64
	SwapPct   float64
}

func (s *Server) dashboard(w http.ResponseWriter, r *http.Request) {
	st := s.sch.Status()
	cfg := s.cfg.Get()
	samples := s.ring.Since(time.Now().Add(-24*time.Hour), 240)
	cpu := make([]float64, len(samples))
	mem := make([]float64, len(samples))
	tmp := make([]float64, len(samples))
	for i, p := range samples {
		cpu[i] = p.CPU
		if st.Mem.Total > 0 {
			mem[i] = float64(p.MemUsed) * 100 / float64(st.Mem.Total)
		}
		tmp[i] = p.CPUTemp
	}
	vm := dashVM{
		S: st, Th: cfg.Thresholds,
		CPUSpark:  sparkline(cpu, 100, "cpu"),
		MemSpark:  sparkline(mem, 100, "mem"),
		TempSpark: sparkline(tmp, 100, "temp"),
	}
	if st.Mem.Total > 0 {
		vm.MemPct = float64(st.Mem.Used) * 100 / float64(st.Mem.Total)
		vm.ARCPct = float64(st.Mem.ARCSize) * 100 / float64(st.Mem.Total)
	}
	if st.Mem.SwapTotal > 0 {
		vm.SwapPct = float64(st.Mem.SwapUsed) * 100 / float64(st.Mem.SwapTotal)
	}
	s.render(w, r, "dashboard", pageData{Title: "Dashboard", Data: vm, Alerts: len(st.Alerts), Flash: r.URL.Query().Get("msg")})
}

type diskVM struct {
	D          sched.DiskView
	Th         config.Thresholds
	History    []store.SmartPoint
	HistoryRev []store.SmartPoint // newest first, capped
	TempSpark  template.HTML
	Known      bool
}

func (s *Server) disk(w http.ResponseWriter, r *http.Request) {
	serial := r.PathValue("serial")
	st := s.sch.Status()
	var vm diskVM
	found := false
	for _, d := range st.Disks {
		if d.Serial == serial {
			vm.D, found = d, true
		}
	}
	if !found {
		// disk may be gone: show what we know from the last snapshot
		if sm, _ := s.st.LastSmart(serial); sm != nil {
			vm.D = sched.DiskView{Smart: sm}
			vm.D.Serial, vm.D.Model, vm.D.Path = sm.Serial, sm.Model, sm.Device
			found = true
		}
	}
	if !found {
		http.NotFound(w, r)
		return
	}
	vm.Th = s.cfg.Get().Thresholds
	vm.History, _ = s.st.SmartHistory(serial, time.Now().Add(-30*24*time.Hour))
	temps := make([]float64, len(vm.History))
	for i, p := range vm.History {
		temps[i] = float64(p.TempC)
	}
	vm.TempSpark = sparkline(temps, 0, "temp")
	for i := len(vm.History) - 1; i >= 0 && len(vm.HistoryRev) < 100; i-- {
		vm.HistoryRev = append(vm.HistoryRev, vm.History[i])
	}
	if seen, _ := s.st.SeenDisks(); seen != nil {
		for _, d := range seen {
			if d.Serial == serial {
				vm.Known = true
			}
		}
	}
	s.render(w, r, "disk", pageData{Title: "Disk " + vm.D.Model, Data: vm, Alerts: len(st.Alerts)})
}

func (s *Server) forgetDisk(w http.ResponseWriter, r *http.Request) {
	_ = s.st.ForgetDisk(r.PathValue("serial"))
	http.Redirect(w, r, "/?msg=Disk+forgotten", http.StatusSeeOther)
}

// ---- ZFS page + dataset management

// defaultOwner is pre-filled in the create form: uid/gid the Docker containers
// on this NAS run as, so a new dataset is writable for them right away.
const defaultOwner = "1000:1000"

type zfsVM struct {
	S        sched.Status
	Th       config.Thresholds
	Datasets []datasetRow
	// PoolDedup maps a pool to the dedup property of its root dataset.
	PoolDedup map[string]string
	Form      createForm // last submitted values (re-rendered after an error)
}

type datasetRow struct {
	collect.Dataset
	CanDestroy bool
	DomID      string
}

type createForm struct {
	Pool, Name, Owner, Compression, Dedup, Quota string
}

func (s *Server) zfsView(st sched.Status, form createForm) zfsVM {
	vm := zfsVM{S: st, Th: s.cfg.Get().Thresholds, Form: form, PoolDedup: map[string]string{}}
	if vm.Form.Owner == "" {
		vm.Form.Owner = defaultOwner
	}
	for _, d := range st.Datasets {
		if !strings.Contains(d.Name, "/") {
			vm.PoolDedup[d.Name] = d.Dedup
		}
		row := datasetRow{Dataset: d, DomID: strings.NewReplacer("/", "-", ".", "_", ":", "_").Replace(d.Name)}
		row.CanDestroy = strings.Contains(d.Name, "/") && d.Refer < zfsadm.EmptyRefer
		for _, o := range st.Datasets {
			if strings.HasPrefix(o.Name, d.Name+"/") {
				row.CanDestroy = false
			}
		}
		vm.Datasets = append(vm.Datasets, row)
	}
	return vm
}

func (s *Server) zfs(w http.ResponseWriter, r *http.Request) {
	st := s.sch.Status()
	s.render(w, r, "zfs", pageData{Title: "ZFS", Data: s.zfsView(st, createForm{}), Alerts: len(st.Alerts), Flash: r.URL.Query().Get("msg")})
}

func (s *Server) zfsCreate(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	f := createForm{
		Pool:        strings.TrimSpace(r.FormValue("pool")),
		Name:        strings.Trim(strings.TrimSpace(r.FormValue("name")), "/"),
		Owner:       strings.TrimSpace(r.FormValue("owner")),
		Compression: r.FormValue("compression"),
		Dedup:       r.FormValue("dedup"),
		Quota:       strings.ToUpper(strings.TrimSpace(r.FormValue("quota"))),
	}
	st := s.sch.Status()
	fail := func(msg string) {
		s.render(w, r, "zfs", pageData{Title: "ZFS", Data: s.zfsView(st, f), Alerts: len(st.Alerts), Error: "Not created: " + msg})
	}
	if !hasPool(st, f.Pool) {
		fail("unknown pool " + f.Pool)
		return
	}
	if err := zfsadm.ValidateRelName(f.Name); err != nil {
		fail(err.Error())
		return
	}
	full := f.Pool + "/" + f.Name
	for _, d := range st.Datasets {
		if d.Name == full {
			fail(full + " already exists")
			return
		}
	}
	for _, err := range []error{zfsadm.ValidateOwner(f.Owner), zfsadm.ValidateCompression(f.Compression), zfsadm.ValidateDedup(f.Dedup), zfsadm.ValidateSize(f.Quota)} {
		if err != nil {
			fail(err.Error())
			return
		}
	}
	err := s.admin.Create(full, zfsadm.CreateOpts{Compression: f.Compression, Dedup: f.Dedup, Quota: f.Quota, Owner: f.Owner})
	s.sch.RefreshStorage()
	if err != nil {
		log.Printf("zfs create %s: %v", full, err)
		fail(err.Error())
		return
	}
	log.Printf("dataset %s created (owner %s, compression %q, dedup %q, quota %q)", full, f.Owner, f.Compression, f.Dedup, f.Quota)
	http.Redirect(w, r, "/zfs?msg="+url.QueryEscape("Dataset "+full+" created")+"#"+url.PathEscape(f.Pool), http.StatusSeeOther)
}

func (s *Server) zfsDestroy(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	name := strings.TrimSpace(r.FormValue("name"))
	st := s.sch.Status()
	fail := func(msg string) {
		s.render(w, r, "zfs", pageData{Title: "ZFS", Data: s.zfsView(st, createForm{}), Alerts: len(st.Alerts), Error: "Not destroyed: " + msg})
	}
	if strings.TrimSpace(r.FormValue("confirm")) != name {
		fail("type the dataset name to confirm")
		return
	}
	eligible := false
	for _, row := range s.zfsView(st, createForm{}).Datasets {
		if row.Name == name {
			eligible = row.CanDestroy
		}
	}
	if !eligible {
		fail(name + " is not an empty dataset")
		return
	}
	err := s.admin.DestroyEmpty(name)
	s.sch.RefreshStorage()
	if err != nil {
		log.Printf("zfs destroy %s: %v", name, err)
		fail(err.Error())
		return
	}
	log.Printf("dataset %s destroyed", name)
	http.Redirect(w, r, "/zfs?msg="+url.QueryEscape("Dataset "+name+" destroyed"), http.StatusSeeOther)
}

// zfsDedup turns dedup on/off on a pool's root dataset (inherited by children).
func (s *Server) zfsDedup(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	pool := strings.TrimSpace(r.FormValue("pool"))
	value := r.FormValue("dedup")
	st := s.sch.Status()
	fail := func(msg string) {
		s.render(w, r, "zfs", pageData{Title: "ZFS", Data: s.zfsView(st, createForm{}), Alerts: len(st.Alerts), Error: "Dedup not changed: " + msg})
	}
	if !hasPool(st, pool) {
		fail("unknown pool " + pool)
		return
	}
	if value != "on" && value != "off" {
		fail("dedup must be on or off")
		return
	}
	err := s.admin.SetDedup(pool, value)
	s.sch.RefreshStorage()
	if err != nil {
		log.Printf("zfs set dedup=%s %s: %v", value, pool, err)
		fail(err.Error())
		return
	}
	log.Printf("dedup=%s set on pool %s", value, pool)
	http.Redirect(w, r, "/zfs?msg="+url.QueryEscape("Dedup "+value+" for "+pool)+"#"+url.PathEscape(pool), http.StatusSeeOther)
}

func hasPool(st sched.Status, name string) bool {
	for _, p := range st.Pools {
		if p.Name == name {
			return true
		}
	}
	return false
}

// ---- alerts

// resolvedWindow is how long resolved alerts stay in the default /alerts view.
const resolvedWindow = 7 * 24 * time.Hour

type alertsVM struct {
	List        []store.Alert
	LastMailErr string
	All         bool
	Hidden      int // resolved alerts outside the window (only when !All)
}

func (s *Server) alerts(w http.ResponseWriter, r *http.Request) {
	vm := alertsVM{All: r.URL.Query().Get("all") == "1"}
	since := time.Time{}
	if !vm.All {
		since = time.Now().Add(-resolvedWindow)
		vm.Hidden, _ = s.st.CountResolvedBefore(since)
	}
	vm.List, _ = s.st.RecentAlerts(500, since)
	st := s.sch.Status()
	vm.LastMailErr = st.LastMailErr
	s.render(w, r, "alerts", pageData{Title: "Alerts", Data: vm, Alerts: len(st.Alerts), Flash: r.URL.Query().Get("msg")})
}

// alertAction handles ack / unack / delete for one alert and sends the browser
// back where it came from.
func (s *Server) alertAction(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.Error(w, "bad id", http.StatusBadRequest)
		return
	}
	a, err := s.st.GetAlert(id)
	if err != nil || a == nil {
		http.NotFound(w, r)
		return
	}
	var msg string
	switch r.PathValue("action") {
	case "ack":
		if a.ResolvedAt != nil {
			http.Error(w, "alert is already resolved", http.StatusConflict)
			return
		}
		err = s.st.AckAlert(id, time.Now())
		msg = "Alert acknowledged"
		log.Printf("alert acknowledged: %s — %s", a.Key, a.Title)
	case "unack":
		err = s.st.UnackAlert(id)
		msg = "Alert shown again"
	case "delete":
		if a.ResolvedAt == nil {
			http.Error(w, "only resolved alerts can be deleted", http.StatusConflict)
			return
		}
		err = s.st.DeleteAlert(id)
		msg = "Alert removed from the log"
	default:
		http.NotFound(w, r)
		return
	}
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	s.sch.RefreshAlerts()
	if r.Header.Get("X-Requested-With") == "fetch" {
		w.WriteHeader(http.StatusNoContent)
		return
	}
	back := r.Header.Get("Referer")
	if back == "" || !strings.HasPrefix(back, "/") && !strings.Contains(back, r.Host) {
		back = "/alerts"
	}
	if u, err := url.Parse(back); err == nil {
		q := u.Query()
		q.Set("msg", msg)
		u.RawQuery = q.Encode()
		back = u.String()
	}
	http.Redirect(w, r, back, http.StatusSeeOther)
}

func (s *Server) smartRun(w http.ResponseWriter, r *http.Request) {
	s.sch.RunSmartNow()
	http.Redirect(w, r, "/?msg=SMART+check+started", http.StatusSeeOther)
}

// ---- settings

type settingsVM struct {
	C       config.Settings
	HasPass bool
	ToText  string
}

func (s *Server) settings(w http.ResponseWriter, r *http.Request) {
	c := s.cfg.Get()
	s.render(w, r, "settings", pageData{Title: "Settings", Data: settingsVM{C: c, HasPass: c.SMTP.Pass != "", ToText: strings.Join(c.SMTP.To, "\n")}})
}

func (s *Server) settingsPost(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	old := s.cfg.Get()
	c := formToSettings(r, old)
	pd := pageData{Title: "Settings"}
	if err := s.cfg.Save(c); err != nil {
		pd.Error = "Not saved: " + err.Error()
		pd.Data = settingsVM{C: c, HasPass: c.SMTP.Pass != "", ToText: strings.Join(c.SMTP.To, "\n")}
		s.render(w, r, "settings", pd)
		return
	}
	s.sch.Reload()
	pd.Flash = "Settings saved."
	if r.FormValue("action") == "test" {
		host := s.sch.Status().Host
		body := "This is a test message from nasmon on " + host + ".\nIf you can read this, alert delivery works."
		if err := s.send(c.SMTP, strings.TrimSpace(c.SMTP.SubjectPrefix+" test message from "+host), body); err != nil {
			pd.Error = "Test mail failed: " + err.Error()
		} else {
			pd.Flash = "Settings saved, test mail sent to " + strings.Join(c.SMTP.To, ", ") + "."
		}
	}
	saved := s.cfg.Get()
	pd.Data = settingsVM{C: saved, HasPass: saved.SMTP.Pass != "", ToText: strings.Join(saved.SMTP.To, "\n")}
	s.render(w, r, "settings", pd)
}

func formToSettings(r *http.Request, old config.Settings) config.Settings {
	num := func(name string, def int) int {
		n, err := strconv.Atoi(strings.TrimSpace(r.FormValue(name)))
		if err != nil {
			return def
		}
		return n
	}
	on := func(name string) bool { return r.FormValue(name) != "" }
	c := old
	c.SMTP.Host = strings.TrimSpace(r.FormValue("smtp_host"))
	c.SMTP.Port = num("smtp_port", 587)
	c.SMTP.Security = r.FormValue("smtp_security")
	c.SMTP.User = strings.TrimSpace(r.FormValue("smtp_user"))
	if p := r.FormValue("smtp_pass"); p != "" {
		c.SMTP.Pass = p
	}
	if on("smtp_clear_pass") {
		c.SMTP.Pass = ""
	}
	c.SMTP.From = strings.TrimSpace(r.FormValue("smtp_from"))
	c.SMTP.SubjectPrefix = strings.TrimSpace(r.FormValue("smtp_prefix"))
	c.SMTP.To = nil
	for _, line := range strings.FieldsFunc(r.FormValue("smtp_to"), func(r rune) bool { return r == '\n' || r == ',' || r == ';' || r == ' ' }) {
		if line = strings.TrimSpace(line); line != "" {
			c.SMTP.To = append(c.SMTP.To, line)
		}
	}
	c.AlertsEnabled = on("alerts_enabled")
	c.NotifyResolved = on("notify_resolved")
	c.RemindHours = num("remind_hours", old.RemindHours)
	c.SmartIntervalMin = num("smart_interval", old.SmartIntervalMin)
	c.SmartSkipStandby = on("smart_skip_standby")
	c.Thresholds.DiskTempC = num("th_disk_temp", old.Thresholds.DiskTempC)
	c.Thresholds.CPUTempC = num("th_cpu_temp", old.Thresholds.CPUTempC)
	c.Thresholds.PoolCapacityPct = num("th_pool_cap", old.Thresholds.PoolCapacityPct)
	c.Thresholds.ScrubMaxAgeDays = num("th_scrub_days", old.Thresholds.ScrubMaxAgeDays)
	c.Thresholds.RootFSFreePct = num("th_rootfs_free", old.Thresholds.RootFSFreePct)
	c.Thresholds.NVMeUsedPct = num("th_nvme_used", old.Thresholds.NVMeUsedPct)
	c.Thresholds.NVMeSparePct = num("th_nvme_spare", old.Thresholds.NVMeSparePct)
	c.SelfTests.Enabled = on("st_enabled")
	c.SelfTests.ShortDays = num("st_short_days", old.SelfTests.ShortDays)
	c.SelfTests.LongDays = num("st_long_days", old.SelfTests.LongDays)
	c.SelfTests.Hour = num("st_hour", old.SelfTests.Hour)
	return c
}

// ---- JSON API

func writeJSON(w http.ResponseWriter, v any) {
	w.Header().Set("Content-Type", "application/json")
	enc := json.NewEncoder(w)
	enc.SetIndent("", " ")
	_ = enc.Encode(v)
}

func (s *Server) apiStatus(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, s.sch.Status())
}

func (s *Server) apiHistory(w http.ResponseWriter, r *http.Request) {
	hours, _ := strconv.Atoi(r.URL.Query().Get("hours"))
	if hours <= 0 || hours > 24 {
		hours = 24
	}
	writeJSON(w, s.ring.Since(time.Now().Add(-time.Duration(hours)*time.Hour), 1000))
}

func (s *Server) apiDiskHistory(w http.ResponseWriter, r *http.Request) {
	days, _ := strconv.Atoi(r.URL.Query().Get("days"))
	if days <= 0 || days > 365 {
		days = 30
	}
	pts, err := s.st.SmartHistory(r.PathValue("serial"), time.Now().Add(-time.Duration(days)*24*time.Hour))
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	if pts == nil {
		pts = []store.SmartPoint{}
	}
	writeJSON(w, pts)
}