package web

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"time"

	"gitea.dooplex.hu/admin/felhom-controller/internal/settings"
	"gitea.dooplex.hu/admin/felhom-controller/internal/stacks"
)

// „Megosztás" — LAN network sharing (R-7 slice 1). The customer enables sharing, sets one household
// SMB password, and exports folders. Every customer-supplied path goes through sharingResolvePath,
// which is load-bearing security, not defence in depth.

// errNotShareable is the single refusal surfaced for every deny-listed / out-of-root path. It is
// deliberately uniform: a distinct message per reason would let the picker act as a filesystem oracle.
var errNotShareable = errors.New("Ez a mappa nem osztható meg.")

// pathWithin reports whether path IS root or lives under it. Segment-wise and separator-agnostic, so
// neither a "/mnt/drive-evil" sibling nor a non-POSIX separator can pass as containment.
func pathWithin(path, root string) bool {
	p := filepath.ToSlash(filepath.Clean(path))
	r := filepath.ToSlash(filepath.Clean(root))
	return p == r || strings.HasPrefix(p, r+"/")
}

// sharingOwningRoot returns the registered, non-decommissioned storage root that contains path.
func (s *Server) sharingOwningRoot(path string) (string, bool) {
	for _, sp := range s.settings.GetStoragePaths() {
		if sp.Decommissioned {
			continue
		}
		if pathWithin(path, sp.Path) {
			return sp.Path, true
		}
	}
	return "", false
}

// sharingResolvePath is THE security gate for this feature. A path is accepted only when it
// (1) is absolute, (2) resolves — SYMLINKS INCLUDED — into a registered live storage root, (3) is not
// inside a deny-listed system subtree (appdata/, backups/, the drive root itself, felhom-data), and
// (4) is a real directory. EvalSymlinks runs BEFORE the containment assert so a symlink planted inside
// a root cannot point outside it.
func (s *Server) sharingResolvePath(raw string) (string, error) {
	if strings.TrimSpace(raw) == "" {
		return "", errNotShareable
	}
	clean := filepath.Clean(raw)
	if !filepath.IsAbs(clean) {
		return "", errNotShareable
	}
	resolved, err := filepath.EvalSymlinks(clean)
	if err != nil {
		return "", errNotShareable
	}
	root, ok := s.sharingOwningRoot(resolved)
	if !ok {
		return "", errNotShareable
	}
	// A whole drive is never shareable (exact match — the subtree rule below must NOT include the
	// root, or every legitimate share under it would be refused).
	if filepath.Clean(resolved) == filepath.Clean(root) {
		return "", errNotShareable
	}
	for _, denied := range stacks.SharingDeniedRoots(root) {
		if pathWithin(resolved, denied) {
			return "", errNotShareable
		}
	}
	fi, err := os.Stat(resolved)
	if err != nil || !fi.IsDir() {
		return "", errNotShareable
	}
	return resolved, nil
}

// sharingPageData assembles the „Megosztás" page state.
func (s *Server) sharingPageData() map[string]interface{} {
	data := s.settingsBaseData("sharing", "Hálózati megosztás")
	smb := s.settings.GetSMBSettings()
	data["SMBEnabled"] = smb.Enabled
	data["SMBServerName"] = smb.EffectiveServerName()
	data["SMBUserSet"] = smb.UserSet
	data["SMBRunning"] = s.stackMgr.SambaRunning()

	type shareRow struct {
		Name      string
		Path      string
		ReadOnly  bool
		Offsite   bool
		Available bool
	}
	var rows []shareRow
	for _, sh := range s.settings.GetSMBShares() {
		fi, err := os.Stat(sh.Path)
		rows = append(rows, shareRow{
			Name: sh.Name, Path: sh.Path, ReadOnly: sh.ReadOnly, Offsite: sh.Offsite,
			Available: err == nil && fi.IsDir(),
		})
	}
	data["SMBShares"] = rows

	// Storage roots offered for the "new folder on a drive" flow.
	var roots []map[string]string
	for _, sp := range s.settings.GetStoragePaths() {
		if sp.Decommissioned || sp.Disconnected {
			continue
		}
		label := sp.Label
		if label == "" {
			label = filepath.Base(sp.Path)
		}
		roots = append(roots, map[string]string{"Path": sp.Path, "Label": label})
	}
	data["StorageRoots"] = roots
	return data
}

func (s *Server) sharingPageHandler(w http.ResponseWriter, r *http.Request) {
	data := s.sharingPageData()
	if f := strings.TrimSpace(r.URL.Query().Get("flash")); f != "" {
		data["Flash"] = f
	}
	s.executeTemplate(w, r, "sharing", data)
}

// sharingRedirect returns to the page with a Hungarian flash.
func sharingRedirect(w http.ResponseWriter, r *http.Request, flash string) {
	http.Redirect(w, r, "/sharing?flash="+urlQueryEscape(flash), http.StatusSeeOther)
}

func urlQueryEscape(s string) string {
	return strings.NewReplacer(" ", "+", "&", "%26", "?", "%3F", "#", "%23").Replace(s)
}

// sharingEnableHandler toggles the feature and updates the server name (POST /sharing/enable).
func (s *Server) sharingEnableHandler(w http.ResponseWriter, r *http.Request) {
	_ = r.ParseForm()
	enable := r.FormValue("enabled") == "on" || r.FormValue("enabled") == "true"
	name := strings.TrimSpace(r.FormValue("server_name"))

	if name != "" {
		if err := settings.ValidateSMBServerName(name); err != nil {
			sharingRedirect(w, r, err.Error())
			return
		}
		if err := s.settings.SetSMBServerName(name); err != nil {
			sharingRedirect(w, r, "A mentés nem sikerült.")
			return
		}
	}
	if err := s.settings.SetSMBEnabled(enable); err != nil {
		sharingRedirect(w, r, "A mentés nem sikerült.")
		return
	}
	if !enable {
		if err := s.stackMgr.DisableSamba(); err != nil {
			s.logger.Printf("[WARN] [sharing] disable failed: %v", err)
		}
		sharingRedirect(w, r, "A hálózati megosztás kikapcsolva. A mappák és a fájlok megmaradtak.")
		return
	}
	if err := s.stackMgr.ReconcileSamba(); err != nil {
		s.logger.Printf("[WARN] [sharing] reconcile failed: %v", err)
	}
	sharingRedirect(w, r, "Beállítás mentve.")
}

// sharingPasswordHandler sets the household SMB password (POST /sharing/password).
// SECRET: the password is read from the form and handed straight to the stacks layer, which puts it
// on smbpasswd's stdin. It is never logged and never persisted.
func (s *Server) sharingPasswordHandler(w http.ResponseWriter, r *http.Request) {
	_ = r.ParseForm()
	pw := r.FormValue("smb_password")
	pw2 := r.FormValue("smb_password_confirm")
	if len(pw) < 8 {
		sharingRedirect(w, r, "A jelszónak legalább 8 karakter hosszúnak kell lennie.")
		return
	}
	if pw != pw2 {
		sharingRedirect(w, r, "A két jelszó nem egyezik.")
		return
	}
	if err := s.stackMgr.SetSMBPassword(pw); err != nil {
		s.logger.Printf("[ERROR] [sharing] password apply failed: %v", err)
		sharingRedirect(w, r, "A jelszó beállítása nem sikerült.")
		return
	}
	if err := s.stackMgr.ReconcileSamba(); err != nil {
		s.logger.Printf("[WARN] [sharing] reconcile after password failed: %v", err)
	}
	sharingRedirect(w, r, "Megosztási jelszó beállítva.")
}

// sharingShareCreateHandler creates a share (POST /sharing/shares). Either a NEW folder under
// <storage>/shares/ or an EXISTING folder picked in the browser — both go through the same guard.
func (s *Server) sharingShareCreateHandler(w http.ResponseWriter, r *http.Request) {
	_ = r.ParseForm()
	name := strings.TrimSpace(r.FormValue("name"))
	mode := r.FormValue("mode") // "new" | "existing"
	readOnly := r.FormValue("read_only") == "on"

	if err := settings.ValidateSMBShareName(name); err != nil {
		sharingRedirect(w, r, err.Error())
		return
	}

	var target string
	switch mode {
	case "new":
		root, err := s.sharingResolvePath(r.FormValue("storage_root"))
		if err != nil {
			sharingRedirect(w, r, errNotShareable.Error())
			return
		}
		dir := filepath.Join(root, "shares", name)
		// The name is already NetBIOS-validated (no slash/dot), but assert containment anyway —
		// a join that escaped its root must never reach MkdirAll.
		if !pathWithin(dir, root) {
			sharingRedirect(w, r, errNotShareable.Error())
			return
		}
		if err := os.MkdirAll(dir, 0o775); err != nil {
			s.logger.Printf("[ERROR] [sharing] mkdir failed: %v", err)
			sharingRedirect(w, r, "A mappa létrehozása nem sikerült.")
			return
		}
		// uid:gid 1000 so apps and both backup tiers see the same ownership as SMB writes.
		if err := os.Chown(dir, 1000, 1000); err != nil {
			s.logger.Printf("[WARN] [sharing] chown 1000:1000 failed: %v", err)
		}
		target = dir
	case "existing":
		resolved, err := s.sharingResolvePath(r.FormValue("path"))
		if err != nil {
			sharingRedirect(w, r, errNotShareable.Error())
			return
		}
		target = resolved
	default:
		sharingRedirect(w, r, errNotShareable.Error())
		return
	}

	share := settings.SMBShare{
		Name:      name,
		Path:      target,
		ReadOnly:  readOnly,
		Offsite:   true, // [R4] new shares default to mandatory (offsite + tier-2)
		CreatedAt: time.Now().UTC().Format(time.RFC3339),
	}
	if err := s.settings.AddSMBShare(share); err != nil {
		sharingRedirect(w, r, err.Error())
		return
	}
	if err := s.stackMgr.ReconcileSamba(); err != nil {
		s.logger.Printf("[WARN] [sharing] reconcile after share create failed: %v", err)
	}
	sharingRedirect(w, r, "A megosztás létrehozva.")
}

// sharingShareDeleteHandler removes a share (POST /sharing/shares/delete). CONFIG ONLY — by
// construction there is no filesystem removal anywhere in this feature.
func (s *Server) sharingShareDeleteHandler(w http.ResponseWriter, r *http.Request) {
	_ = r.ParseForm()
	name := strings.TrimSpace(r.FormValue("name"))
	if err := s.settings.RemoveSMBShare(name); err != nil {
		sharingRedirect(w, r, err.Error())
		return
	}
	if err := s.stackMgr.ReconcileSamba(); err != nil {
		s.logger.Printf("[WARN] [sharing] reconcile after share delete failed: %v", err)
	}
	sharingRedirect(w, r, "A megosztás törölve — a mappa és a fájlok megmaradtak.")
}

// sharingShareOffsiteHandler flips a share's „Felhőmentés" toggle (POST /sharing/shares/offsite).
func (s *Server) sharingShareOffsiteHandler(w http.ResponseWriter, r *http.Request) {
	_ = r.ParseForm()
	name := strings.TrimSpace(r.FormValue("name"))
	on := r.FormValue("offsite") == "on" || r.FormValue("offsite") == "true"
	if err := s.settings.SetSMBShareOffsite(name, on); err != nil {
		sharingRedirect(w, r, err.Error())
		return
	}
	sharingRedirect(w, r, "Beállítás mentve.")
}

// sharingBrowseHandler is the folder picker (GET /api/sharing/browse?path=). With no path it lists
// the registered live storage roots; otherwise the sub-DIRECTORIES of a guard-approved path, sorted.
// Deny-listed children are omitted so the picker never offers an unshareable folder.
func (s *Server) sharingBrowseHandler(w http.ResponseWriter, r *http.Request) {
	type entry struct {
		Name string `json:"name"`
		Path string `json:"path"`
	}
	resp := struct {
		Path    string  `json:"path"`
		Parent  string  `json:"parent,omitempty"`
		Entries []entry `json:"entries"`
		Error   string  `json:"error,omitempty"`
	}{Entries: []entry{}}

	raw := r.URL.Query().Get("path")
	if strings.TrimSpace(raw) == "" {
		for _, sp := range s.settings.GetStoragePaths() {
			if sp.Decommissioned || sp.Disconnected {
				continue
			}
			label := sp.Label
			if label == "" {
				label = filepath.Base(sp.Path)
			}
			resp.Entries = append(resp.Entries, entry{Name: label, Path: sp.Path})
		}
		sort.Slice(resp.Entries, func(i, j int) bool { return resp.Entries[i].Name < resp.Entries[j].Name })
		writeSharingJSON(w, http.StatusOK, resp)
		return
	}

	dir, err := s.sharingResolvePath(raw)
	if err != nil {
		resp.Error = errNotShareable.Error()
		writeSharingJSON(w, http.StatusBadRequest, resp)
		return
	}
	resp.Path = dir
	if root, ok := s.sharingOwningRoot(dir); ok && dir != root {
		resp.Parent = filepath.Dir(dir)
	}

	items, rerr := os.ReadDir(dir)
	if rerr != nil {
		resp.Error = "A mappa nem érhető el."
		writeSharingJSON(w, http.StatusBadRequest, resp)
		return
	}
	root, _ := s.sharingOwningRoot(dir)
	denied := stacks.SharingDeniedRoots(root)
	for _, it := range items {
		if !it.IsDir() || strings.HasPrefix(it.Name(), ".") {
			continue
		}
		child := filepath.Join(dir, it.Name())
		skip := false
		for _, d := range denied {
			if pathWithin(child, d) {
				skip = true
				break
			}
		}
		if skip {
			continue
		}
		resp.Entries = append(resp.Entries, entry{Name: it.Name(), Path: child})
	}
	sort.Slice(resp.Entries, func(i, j int) bool { return resp.Entries[i].Name < resp.Entries[j].Name })
	writeSharingJSON(w, http.StatusOK, resp)
}

func writeSharingJSON(w http.ResponseWriter, code int, v interface{}) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(code)
	if err := json.NewEncoder(w).Encode(v); err != nil {
		fmt.Fprintf(w, `{"error":"encode"}`)
	}
}