package hammerhead

import (
	"encoding/json"
	"errors"
	"fmt"
	"net"
	"net/http"
	"strings"
	"time"

	"git.veillax.com/Veillax/reef/model"
	"golang.org/x/crypto/bcrypt"
)

type mappingInput struct {
	model.Mapping
	NewPassword *string `json:"newPassword"` // nil = keep, "" = remove
	NewPin      *string `json:"newPin"`
}

type mappingView struct {
	model.Mapping
	Status model.MappingStatus `json:"status"`
	Known  bool                `json:"statusKnown"`
	Total  Total               `json:"total"`
}

func isWild(ip string) bool {
	p := net.ParseIP(ip)
	return p != nil && p.IsUnspecified()
}

func overlap(a, b string) bool { return a == b || isWild(a) || isWild(b) }

func netClass(proto string) string {
	if proto == model.ProtoUDP {
		return "udp"
	}
	return "tcp"
}

func listFromCSV(in []string) []string {
	out := []string{}
	seen := map[string]bool{}
	for _, v := range in {
		v = strings.ToLower(strings.TrimSpace(v))
		if v != "" && !seen[v] {
			seen[v] = true
			out = append(out, v)
		}
	}
	return out
}

// normalizeTags trims tags, drops blanks and repeats (ignoring case; the first spelling wins)
// and keeps the list short enough to stay readable in the dashboard.
func normalizeTags(in []string) ([]string, error) {
	var out []string
	seen := map[string]bool{}
	for _, t := range in {
		t = strings.Join(strings.Fields(t), " ")
		if t == "" || seen[strings.ToLower(t)] {
			continue
		}
		if len([]rune(t)) > 32 {
			return nil, errors.New("A tag can be at most 32 characters.")
		}
		if strings.ContainsAny(t, ",<>\"") {
			return nil, errors.New("Tags can't contain commas, quotes or angle brackets.")
		}
		seen[strings.ToLower(t)] = true
		out = append(out, t)
	}
	if len(out) > 10 {
		return nil, errors.New("Use at most 10 tags.")
	}
	return out, nil
}

// validateMapping checks m against org c and normalises it. Caller holds s.mu.
func (s *Server) validateMapping(c *orgCtx, m *model.Mapping) error {
	m.Name = strings.TrimSpace(m.Name)
	tags, err := normalizeTags(m.Tags)
	if err != nil {
		return err
	}
	m.Tags = tags
	m.Hostname = strings.ToLower(strings.TrimSpace(m.Hostname))
	m.OrgID = c.Org.ID
	switch m.Proto {
	case model.ProtoTCP, model.ProtoUDP, model.ProtoHTTP, model.ProtoHTTPS, model.ProtoTLS:
	default:
		return errors.New("protocol must be tcp, udp, http, https or tls")
	}
	edge := s.findEdge(m.EdgeID)
	if edge == nil || !s.edgeAllowedFor(edge, c.Org.ID) {
		return errors.New("choose an edge")
	}
	if len(m.Targets) == 0 {
		return errors.New("add at least one target")
	}
	if m.Proto == model.ProtoUDP && len(m.Targets) > 1 {
		return errors.New("udp ports support one target")
	}
	for i := range m.Targets {
		t := &m.Targets[i]
		t.Host = strings.TrimSpace(t.Host)
		site := s.findSite(t.SiteID)
		if site == nil || !s.siteVisible(c, site) {
			return errors.New("choose a site for every target")
		}
		if site.Local && site.EdgeID != m.EdgeID {
			return errors.New("a local site can only be used with its own edge")
		}
		if t.Host == "" {
			return errors.New("every target needs a host (e.g. 127.0.0.1 or 192.168.1.20)")
		}
		if t.Port < 1 || t.Port > 65535 {
			return errors.New("Target ports must be between 1 and 65535.")
		}
	}
	if m.BindIP == "" {
		m.BindIP = "0.0.0.0"
	}
	ip := net.ParseIP(m.BindIP)
	if ip == nil {
		return errors.New("bind IP is not a valid address")
	}
	m.BindIP = ip.String()
	if m.Port < 1 || m.Port > 65535 {
		return errors.New("The public port must be between 1 and 65535.")
	}
	switch {
	case m.PortEnd == 0 || m.PortEnd == m.Port:
		m.PortEnd = 0
	case m.PortEnd < m.Port:
		return errors.New("the end of a port range can't be before its start")
	case m.PortEnd > 65535:
		return errors.New("Public ports must be between 1 and 65535.")
	case m.Proto != model.ProtoTCP && m.Proto != model.ProtoUDP:
		return errors.New("port ranges work for tcp and udp only")
	case m.PortEnd-m.Port+1 > 1000:
		return errors.New("a range can open at most 1000 ports")
	}
	for _, t := range m.Targets {
		if t.Port+m.LastPort()-m.Port > 65535 {
			return errors.New("the target ports would run past 65535: each public port maps to the target port plus the same offset")
		}
	}

	if model.HostBased(m.Proto) {
		if m.Hostname == "" {
			return errors.New("a hostname is required for http, https and tls ports")
		}
		if !validHostname(m.Hostname) {
			return errors.New("hostname looks invalid (use something like app.example.com or *.example.com)")
		}
		if !s.hostnameAllowed(c.Org.ID, m.Hostname) {
			return fmt.Errorf("%s isn't under one of your domains; add the domain on the Domains tab first", m.Hostname)
		}
	} else {
		m.Hostname = ""
	}

	switch m.ProxyProtocol {
	case "":
	case "v1", "v2":
		if m.Proto != model.ProtoTCP && m.Proto != model.ProtoTLS {
			return errors.New("the PROXY protocol is for tcp and tls ports (web ports already pass the client address in X-Forwarded-For)")
		}
	default:
		return errors.New("PROXY protocol must be v1, v2 or off")
	}
	// web-only options
	if !model.Web(m.Proto) {
		m.Auth, m.Rules, m.RewriteHost = model.Auth{}, nil, ""
		m.RedirectHTTP, m.BackendHTTPS, m.HealthPath = false, false, ""
	} else {
		a := &m.Auth
		a.AllowedRoles, a.AllowedUsers, a.AllowedMails = listFromCSV(a.AllowedRoles), listFromCSV(a.AllowedUsers), listFromCSV(a.AllowedMails)
		for _, id := range a.AllowedRoles {
			if r := s.findRole(id); r == nil || r.OrgID != c.Org.ID {
				return errors.New("an allowed role doesn't belong to this organization")
			}
		}
		for _, id := range a.AllowedUsers {
			if s.member(id, c.Org.ID) == nil {
				return errors.New("an allowed user isn't a member of this organization")
			}
		}
		if a.Email && len(a.AllowedMails) == 0 {
			return errors.New("email codes need at least one allowed address (or *@example.com)")
		}
		if a.SessionHours < 0 || a.SessionHours > 24*90 {
			return errors.New("session length must be between 1 hour and 90 days")
		}
		for _, r := range m.Rules {
			if r.Action != "allow" && r.Action != "deny" {
				return errors.New("rule action must be allow or deny")
			}
			switch r.Match {
			case "path":
				if !strings.HasPrefix(r.Value, "/") {
					return errors.New("path rules must start with /")
				}
			case "ip":
				if net.ParseIP(r.Value) == nil {
					if _, _, err := net.ParseCIDR(r.Value); err != nil {
						return fmt.Errorf("%q is not an IP address or CIDR range", r.Value)
					}
				}
			default:
				return errors.New("rule match must be path or ip")
			}
		}
		m.RewriteHost = strings.TrimSpace(m.RewriteHost)
		if m.Proto != model.ProtoHTTPS {
			m.RedirectHTTP = false
		}
		if m.HealthPath != "" && !strings.HasPrefix(m.HealthPath, "/") {
			return errors.New("health check path must start with /")
		}
	}
	if m.HealthSeconds != 0 && m.HealthSeconds != -1 && (m.HealthSeconds < 5 || m.HealthSeconds > 3600) {
		return errors.New("The health check interval must be 5 to 3600 seconds, or off.")
	}

	for _, o := range s.st.Mappings {
		if o.ID == m.ID || o.EdgeID != m.EdgeID || netClass(o.Proto) != netClass(m.Proto) || !overlap(o.BindIP, m.BindIP) ||
			o.Port > m.LastPort() || m.Port > o.LastPort() {
			continue
		}
		if m.Proto == o.Proto && model.HostBased(m.Proto) && m.BindIP == o.BindIP && m.Hostname != o.Hostname {
			continue // same listener, different hostname
		}
		if m.Proto == o.Proto && model.Web(m.Proto) && m.BindIP != o.BindIP && isWild(m.BindIP) != isWild(o.BindIP) {
			continue // a website on every address steps aside for one that names an address
		}
		return fmt.Errorf("%s port %s on %s is already used by %q. Choose another port or address.", strings.ToUpper(netClass(m.Proto)), portLabel(*m), o.BindIP, o.Name)
	}
	// an https resource with the redirect on also answers on port 80 at its address, so a raw port
	// there would clash with it (and the other way round)
	for _, o := range s.st.Mappings {
		if o.ID == m.ID || o.EdgeID != m.EdgeID || !overlap(o.BindIP, m.BindIP) {
			continue
		}
		switch {
		case m.Proto == model.ProtoHTTPS && m.RedirectHTTP && netClass(o.Proto) == "tcp" && !model.Web(o.Proto) && o.Port <= 80 && 80 <= o.LastPort():
			return fmt.Errorf("Redirecting HTTP to HTTPS also uses TCP port 80 on %s, which %q uses. Turn the redirect off or choose another port for %q.", o.BindIP, o.Name, o.Name)
		case o.Proto == model.ProtoHTTPS && o.RedirectHTTP && netClass(m.Proto) == "tcp" && !model.Web(m.Proto) && m.Port <= 80 && 80 <= m.LastPort():
			return fmt.Errorf("TCP port 80 on %s is also used by %q to redirect HTTP to HTTPS. Choose another port, or turn that redirect off.", o.BindIP, o.Name)
		}
	}
	if m.Name == "" {
		if m.Hostname != "" {
			m.Name = m.Hostname
		} else {
			m.Name = fmt.Sprintf("%s %s:%s", m.Proto, m.BindIP, portLabel(*m))
		}
	}
	return nil
}

// portLabel is "25565" or, for a range, "2456-2458".
func portLabel(m model.Mapping) string {
	if m.LastPort() > m.Port {
		return fmt.Sprintf("%d-%d", m.Port, m.LastPort())
	}
	return fmt.Sprint(m.Port)
}

func checkPIN(p string) error {
	if len(p) < 4 || len(p) > 12 {
		return errors.New("A PIN is 4 to 12 digits.")
	}
	for _, c := range p {
		if c < '0' || c > '9' {
			return errors.New("a PIN is digits only")
		}
	}
	return nil
}

// applySecrets updates the password/PIN for mapping id and syncs the Auth flags. Caller holds s.mu.
func (s *Server) applySecrets(m *model.Mapping, pwHash, pinHash *string) {
	sec := s.st.Secrets[m.ID]
	if sec == nil {
		sec = &Secret{}
	}
	if pwHash != nil {
		sec.PasswordHash = *pwHash
	}
	if pinHash != nil {
		sec.PinHash = *pinHash
	}
	if !m.Auth.Password {
		sec.PasswordHash = ""
	}
	if !m.Auth.Pin {
		sec.PinHash = ""
	}
	m.Auth.Password, m.Auth.Pin = sec.PasswordHash != "", sec.PinHash != ""
	if sec.PasswordHash == "" && sec.PinHash == "" {
		delete(s.st.Secrets, m.ID)
	} else {
		s.st.Secrets[m.ID] = sec
	}
}

// hashSecrets prepares optional new secrets outside the lock (bcrypt is slow).
func hashSecrets(in *mappingInput) (pw, pin *string, err error) {
	one := func(v *string, check func(string) error) (*string, error) {
		if v == nil {
			return nil, nil
		}
		if *v == "" {
			e := ""
			return &e, nil
		}
		if err := check(*v); err != nil {
			return nil, err
		}
		b, err := bcrypt.GenerateFromPassword([]byte(*v), 10)
		h := string(b)
		return &h, err
	}
	if pw, err = one(in.NewPassword, func(p string) error {
		if len(p) < 6 {
			return errors.New("a resource password needs at least 6 characters")
		}
		return nil
	}); err != nil {
		return
	}
	pin, err = one(in.NewPin, checkPIN)
	return
}

func (s *Server) addMapping(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	var in mappingInput
	if !decode(w, r, &in) {
		return
	}
	pw, pin, err := hashSecrets(&in)
	if err != nil {
		fail(w, 400, err)
		return
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	m := in.Mapping
	m.ID, m.AuthEpoch = "", 0
	if err := s.validateMapping(c, &m); err != nil {
		fail(w, 400, err)
		return
	}
	m.ID = newID()
	s.applySecrets(&m, pw, pin)
	s.st.Mappings = append(s.st.Mappings, &m)
	s.bump()
	s.audit(c.Org.ID, c.Actor, "mapping.create", m.Name)
	writeJSON(w, 200, m)
}

// authChanged reports whether an edit changes who may open a resource, which
// must sign existing visitors out (their old sessions were granted under the old rules).
func authChanged(o, n model.Auth, pwChanged, pinChanged bool) bool {
	o.SessionHours, n.SessionHours = 0, 0
	ob, _ := json.Marshal(o)
	nb, _ := json.Marshal(n)
	return pwChanged || pinChanged || string(ob) != string(nb)
}

// revokeOrgVisitorsLocked signs out every visitor of the org's protected resources.
// The caller must then call s.bump() so the edges learn the new epoch.
func (s *Server) revokeOrgVisitorsLocked(orgID string) {
	for _, m := range s.st.Mappings {
		if m.OrgID == orgID && m.Auth.Protected() {
			m.AuthEpoch++
		}
	}
}

// revokeVisitors signs everyone out of one resource.
func (s *Server) revokeVisitors(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	s.mu.Lock()
	defer s.mu.Unlock()
	m := s.findMapping(r.PathValue("id"))
	if m == nil || m.OrgID != c.Org.ID {
		fail(w, 404, errors.New("no such port"))
		return
	}
	m.AuthEpoch++
	s.bump()
	s.audit(c.Org.ID, c.Actor, "mapping.signout-visitors", m.Name)
	ok(w)
}

func (s *Server) putMapping(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	var in mappingInput
	if !decode(w, r, &in) {
		return
	}
	pw, pin, err := hashSecrets(&in)
	if err != nil {
		fail(w, 400, err)
		return
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	id := r.PathValue("id")
	for i, old := range s.st.Mappings {
		if old.ID != id || old.OrgID != c.Org.ID {
			continue
		}
		m := in.Mapping
		m.ID = id
		if err := s.validateMapping(c, &m); err != nil {
			fail(w, 400, err)
			return
		}
		s.applySecrets(&m, pw, pin)
		m.AuthEpoch = old.AuthEpoch // only hammerhead moves this, never the request
		if authChanged(old.Auth, m.Auth, pw != nil, pin != nil) {
			m.AuthEpoch++
		}
		s.st.Mappings[i] = &m
		delete(s.status, id)
		s.bump()
		s.audit(c.Org.ID, c.Actor, "mapping.update", m.Name)
		writeJSON(w, 200, m)
		return
	}
	fail(w, 404, errors.New("no such port"))
}

func (s *Server) deleteMapping(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	id := r.PathValue("id")
	s.mu.Lock()
	defer s.mu.Unlock()
	m := s.findMapping(id)
	if m == nil || m.OrgID != c.Org.ID {
		fail(w, 404, errors.New("no such port"))
		return
	}
	s.dropMappingLocked(id)
	s.st.Mappings = filter(s.st.Mappings, func(o *model.Mapping) bool { return o.ID != id })
	s.bump()
	s.audit(c.Org.ID, c.Actor, "mapping.delete", m.Name)
	ok(w)
}

// ---------- share links ----------

func (s *Server) listShares(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	s.mu.Lock()
	defer s.mu.Unlock()
	out := []ShareLink{}
	for _, l := range s.st.Shares {
		if l.OrgID == c.Org.ID && l.MappingID == r.PathValue("id") {
			cp := *l
			cp.TokenHash = ""
			out = append(out, cp)
		}
	}
	writeJSON(w, 200, out)
}

// publicURL is how visitors reach a web mapping, or "" for wildcard hostnames.
func publicURL(m *model.Mapping) string {
	if !model.Web(m.Proto) || m.Hostname == "" || strings.HasPrefix(m.Hostname, "*") {
		return ""
	}
	if m.Proto == model.ProtoHTTPS {
		if m.Port == 443 {
			return "https://" + m.Hostname
		}
		return fmt.Sprintf("https://%s:%d", m.Hostname, m.Port)
	}
	if m.Port == 80 {
		return "http://" + m.Hostname
	}
	return fmt.Sprintf("http://%s:%d", m.Hostname, m.Port)
}

func (s *Server) createShare(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	var in struct {
		Name    string
		Hours   int
		MaxUses int
	}
	if !decode(w, r, &in) {
		return
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	m := s.findMapping(r.PathValue("id"))
	if m == nil || m.OrgID != c.Org.ID {
		fail(w, 404, errors.New("no such port"))
		return
	}
	base := publicURL(m)
	if base == "" {
		fail(w, 400, errors.New("share links need a web port with one concrete hostname"))
		return
	}
	if !m.Auth.Protected() {
		fail(w, 400, errors.New("this port has no login in front of it, so there is nothing to share past"))
		return
	}
	tok := randHex(20)
	l := &ShareLink{ID: newID(), MappingID: m.ID, OrgID: c.Org.ID, Name: strings.TrimSpace(in.Name),
		TokenHash: sha(tok), MaxUses: in.MaxUses, Created: time.Now()}
	if in.Hours > 0 {
		l.Expires = time.Now().Add(time.Duration(in.Hours) * time.Hour)
	}
	s.st.Shares = append(s.st.Shares, l)
	s.save()
	s.audit(c.Org.ID, c.Actor, "share.create", m.Name)
	writeJSON(w, 200, map[string]string{"url": base + "/?hh_share=" + tok})
}

func (s *Server) deleteShare(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	id := r.PathValue("share")
	s.mu.Lock()
	defer s.mu.Unlock()
	for _, l := range s.st.Shares {
		if l.ID == id && l.OrgID == c.Org.ID {
			// sessions started from a share link can't be told apart from others, so
			// revoking one signs out everyone on that resource
			if m := s.findMapping(l.MappingID); m != nil {
				m.AuthEpoch++
			}
		}
	}
	s.st.Shares = filter(s.st.Shares, func(l *ShareLink) bool { return !(l.ID == id && l.OrgID == c.Org.ID) })
	s.bump()
	ok(w)
}

// ---------- combined state for the UI ----------

func (s *Server) orgState(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	s.mu.Lock()
	defer s.mu.Unlock()
	edges := []edgeView{}
	for _, e := range s.st.Edges {
		if s.edgeAllowedFor(e, c.Org.ID) {
			edges = append(edges, s.viewEdge(e, false))
		}
	}
	sites := []model.Site{}
	online := map[string]bool{}
	for _, st := range s.st.Sites {
		if !s.siteVisible(c, st) {
			continue
		}
		cp := *st
		if !c.Admin || st.Local {
			cp.Token = ""
		}
		sites = append(sites, cp)
		online[st.ID] = s.siteOnline(st)
	}
	domains := []model.Domain{}
	for _, d := range s.st.Domains {
		if d.OrgID == c.Org.ID {
			domains = append(domains, *d)
		}
	}
	maps := []mappingView{}
	for _, m := range s.st.Mappings {
		if m.OrgID != c.Org.ID {
			continue
		}
		v := mappingView{Mapping: *m}
		v.Status, v.Known = s.status[m.ID]
		if t := s.st.Totals[m.ID]; t != nil {
			v.Total = *t
		}
		maps = append(maps, v)
	}
	writeJSON(w, 200, map[string]any{
		"org": c.Org, "admin": c.Admin, "edges": edges, "sites": sites, "online": online,
		"domains": domains, "mappings": maps, "roles": s.rolesLocked(c.Org.ID), "mailEgress": s.mailEgressViewsLocked(c.Org.ID),
		"mailConfigured": s.st.Settings.SMTP.Host != "",
		"dashboardUrl":   s.st.Settings.DashboardURL,
	})
}