package hammerhead

import (
	"errors"
	"net"
	"net/http"
	"sort"
	"strings"
	"time"

	"git.veillax.com/Veillax/reef/model"
)

const onlineWindow = 60 * time.Second

func (s *Server) edgeOnline(e *model.Edge) bool { return time.Since(e.LastSeen) < onlineWindow }

// edgeView is what browsers see. Only server admins get tokens and org lists.
type edgeView struct {
	ID         string   `json:"id"`
	Name       string   `json:"name"`
	IPs        []string `json:"ips"`
	Online     bool     `json:"online"`
	TunnelAddr string   `json:"tunnelAddr,omitempty"`
	Token      string   `json:"token,omitempty"`
	OrgIDs     []string `json:"orgIds,omitempty"`

	Version       string `json:"version,omitempty"`
	AutoUpdate    bool   `json:"autoUpdate,omitempty"`
	UpdatePending bool   `json:"updatePending,omitempty"`
	UpdateMsg     string `json:"updateMsg,omitempty"`
}

func (s *Server) viewEdge(e *model.Edge, admin bool) edgeView {
	v := edgeView{ID: e.ID, Name: e.Name, IPs: e.IPs, Online: s.edgeOnline(e)}
	if v.IPs == nil {
		v.IPs = []string{}
	}
	if admin {
		v.TunnelAddr, v.Token, v.OrgIDs = e.TunnelAddr, e.Token, e.OrgIDs
		v.Version, v.AutoUpdate, v.UpdatePending, v.UpdateMsg = e.Version, e.AutoUpdate, e.UpdateID != "", e.UpdateMsg
		if v.OrgIDs == nil {
			v.OrgIDs = []string{}
		}
	}
	return v
}

func validAddr(a string) bool {
	h, p, err := net.SplitHostPort(a)
	if err != nil || h == "" {
		return false
	}
	n := 0
	for _, c := range p {
		if c < '0' || c > '9' {
			return false
		}
		n = n*10 + int(c-'0')
		if n > 65535 {
			return false
		}
	}
	return n > 0
}

func (s *Server) listEdges(w http.ResponseWriter, r *http.Request, p *principal) {
	s.mu.Lock()
	defer s.mu.Unlock()
	out := []edgeView{}
	for _, e := range s.st.Edges {
		if p.User.ServerAdmin {
			out = append(out, s.viewEdge(e, true))
			continue
		}
		for _, m := range s.st.Members {
			if m.UserID == p.User.ID && s.edgeAllowedFor(e, m.OrgID) {
				out = append(out, s.viewEdge(e, false))
				break
			}
		}
	}
	writeJSON(w, 200, out)
}

func (s *Server) saveEdge(w http.ResponseWriter, r *http.Request, p *principal) {
	var in model.Edge
	if !decode(w, r, &in) {
		return
	}
	in.Name = strings.TrimSpace(in.Name)
	if in.Name == "" {
		fail(w, 400, errors.New("name is required"))
		return
	}
	if !validAddr(in.TunnelAddr) {
		fail(w, 400, errors.New("WireGuard endpoint must look like host:port (the edge's public address and UDP port)"))
		return
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	for _, o := range in.OrgIDs {
		if s.findOrg(o) == nil {
			fail(w, 400, errors.New("unknown organization in the allowed list"))
			return
		}
	}
	if id := r.PathValue("id"); id != "" {
		e := s.findEdge(id)
		if e == nil {
			fail(w, 404, errors.New("no such edge"))
			return
		}
		e.Name, e.TunnelAddr, e.OrgIDs = in.Name, in.TunnelAddr, in.OrgIDs
		for _, st := range s.st.Sites {
			if st.Local && st.EdgeID == e.ID {
				st.Name = e.Name + " (this machine)"
			}
		}
		s.bump()
		writeJSON(w, 200, s.viewEdge(e, true))
		return
	}
	e := &model.Edge{ID: newID(), Name: in.Name, Token: randHex(24), AuthKey: randHex(32),
		TunnelAddr: in.TunnelAddr, TunnelIP: s.allocIPLocked(), OrgIDs: in.OrgIDs, IPs: []string{}}
	s.st.Edges = append(s.st.Edges, e)
	// every edge gets a built-in site for services on the edge's own machine
	s.st.Sites = append(s.st.Sites, &model.Site{ID: newID(), Name: in.Name + " (this machine)",
		Local: true, EdgeID: e.ID, Connected: []string{}})
	s.bump()
	s.audit("", p.User.Email, "edge.create", e.Name)
	writeJSON(w, 200, s.viewEdge(e, true))
}

func (s *Server) deleteEdge(w http.ResponseWriter, r *http.Request, p *principal) {
	id := r.PathValue("id")
	s.mu.Lock()
	defer s.mu.Unlock()
	e := s.findEdge(id)
	if e == nil {
		fail(w, 404, errors.New("no such edge"))
		return
	}
	s.st.Edges = filter(s.st.Edges, func(x *model.Edge) bool { return x.ID != id })
	s.st.Sites = filter(s.st.Sites, func(x *model.Site) bool { return !(x.Local && x.EdgeID == id) })
	s.st.Domains = filter(s.st.Domains, func(d *model.Domain) bool { return d.EdgeID != id })
	s.st.MailEgress = filter(s.st.MailEgress, func(x *model.MailEgress) bool { return x.EdgeID != id })
	for _, m := range s.st.Mappings {
		if m.EdgeID == id {
			s.dropMappingLocked(m.ID)
		}
	}
	s.st.Mappings = filter(s.st.Mappings, func(m *model.Mapping) bool { return m.EdgeID != id })
	s.bump()
	s.audit("", p.User.Email, "edge.delete", e.Name)
	ok(w)
}

// dropMappingLocked removes everything hanging off a mapping except the mapping itself.
func (s *Server) dropMappingLocked(id string) {
	delete(s.st.Secrets, id)
	delete(s.st.Totals, id)
	delete(s.status, id)
	s.st.Shares = filter(s.st.Shares, func(l *ShareLink) bool { return l.MappingID != id })
}

// ---------- sites ----------

func (s *Server) siteVisible(c *orgCtx, st *model.Site) bool {
	if st.Local {
		if !c.Org.AllowLocal {
			return false
		}
		e := s.findEdge(st.EdgeID)
		return e != nil && s.edgeAllowedFor(e, c.Org.ID)
	}
	return st.OrgID == c.Org.ID
}

func (s *Server) siteOnline(st *model.Site) bool {
	if st.Local {
		e := s.findEdge(st.EdgeID)
		return e != nil && s.edgeOnline(e)
	}
	return time.Since(st.LastSeen) < onlineWindow
}

func (s *Server) addSite(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	var in struct{ Name string }
	if !decode(w, r, &in) {
		return
	}
	in.Name = strings.TrimSpace(in.Name)
	if in.Name == "" {
		fail(w, 400, errors.New("name is required"))
		return
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	st := &model.Site{ID: newID(), OrgID: c.Org.ID, Name: in.Name, Token: randHex(24), Connected: []string{}, TunnelIP: s.allocIPLocked()}
	s.st.Sites = append(s.st.Sites, st)
	s.bump()
	s.audit(c.Org.ID, c.Actor, "site.create", in.Name)
	writeJSON(w, 200, st)
}

// putSite renames a site and sets its tags. The built-in local site is shared between
// organizations, so it can't be edited here.
func (s *Server) putSite(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	var in struct {
		Name string   `json:"name"`
		Tags []string `json:"tags"`
	}
	if !decode(w, r, &in) {
		return
	}
	in.Name = strings.TrimSpace(in.Name)
	if in.Name == "" {
		fail(w, 400, errors.New("name is required"))
		return
	}
	tags, err := normalizeTags(in.Tags)
	if err != nil {
		fail(w, 400, err)
		return
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	st := s.findSite(r.PathValue("id"))
	if st == nil || st.OrgID != c.Org.ID {
		fail(w, 404, errors.New("no such site"))
		return
	}
	if st.Local {
		fail(w, 400, errors.New("the built-in local site can't be edited"))
		return
	}
	st.Name, st.Tags = in.Name, tags
	s.bump()
	s.audit(c.Org.ID, c.Actor, "site.update", st.Name)
	ok(w)
}

func (s *Server) deleteSite(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	id := r.PathValue("id")
	s.mu.Lock()
	defer s.mu.Unlock()
	st := s.findSite(id)
	if st == nil || st.OrgID != c.Org.ID {
		fail(w, 404, errors.New("no such site"))
		return
	}
	if st.Local {
		fail(w, 400, errors.New("the built-in local site goes away with its edge"))
		return
	}
	s.st.Sites = filter(s.st.Sites, func(e *model.Site) bool { return e.ID != id })
	s.st.MailEgress = filter(s.st.MailEgress, func(x *model.MailEgress) bool { return x.SiteID != id })
	for _, m := range s.st.Mappings {
		kept := []model.Target{}
		for _, t := range m.Targets {
			if t.SiteID != id {
				kept = append(kept, t)
			}
		}
		if len(kept) != len(m.Targets) {
			m.Targets = kept
			if len(kept) == 0 {
				s.dropMappingLocked(m.ID)
			}
		}
	}
	s.st.Mappings = filter(s.st.Mappings, func(m *model.Mapping) bool { return len(m.Targets) > 0 || m.IsRedirect() })
	s.bump()
	s.audit(c.Org.ID, c.Actor, "site.delete", st.Name)
	ok(w)
}

func (s *Server) siteContainers(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	s.mu.Lock()
	defer s.mu.Unlock()
	st := s.findSite(r.PathValue("id"))
	if st == nil || !s.siteVisible(c, st) {
		fail(w, 404, errors.New("no such site"))
		return
	}
	out := s.containers[st.ID]
	if out == nil {
		out = []model.Container{}
	}
	writeJSON(w, 200, out)
}

// ---------- domains ----------

func domainsOverlap(a, b string) bool {
	return a == b || strings.HasSuffix(a, "."+b) || strings.HasSuffix(b, "."+a)
}

func validHostname(h string) bool {
	h = strings.TrimPrefix(h, "*.")
	if h == "" || len(h) > 253 || !strings.Contains(h, ".") {
		return false
	}
	for _, c := range h {
		if !(c >= 'a' && c <= 'z' || c >= '0' && c <= '9' || c == '-' || c == '.') {
			return false
		}
	}
	return !strings.HasPrefix(h, ".") && !strings.HasSuffix(h, ".") && !strings.Contains(h, "..")
}

func (s *Server) addDomain(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	var in model.Domain
	if !decode(w, r, &in) {
		return
	}
	in.Name = strings.ToLower(strings.TrimSpace(in.Name))
	if !validHostname(in.Name) || strings.HasPrefix(in.Name, "*.") {
		fail(w, 400, errors.New("enter a domain like example.com"))
		return
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	if in.EdgeID != "" {
		e := s.findEdge(in.EdgeID)
		if e == nil || !s.edgeAllowedFor(e, c.Org.ID) {
			fail(w, 400, errors.New("choose an edge"))
			return
		}
	}
	for _, d := range s.st.Domains {
		if d.OrgID != c.Org.ID && domainsOverlap(d.Name, in.Name) {
			fail(w, 400, errors.New("that domain (or a parent/child of it) belongs to another organization"))
			return
		}
		if d.OrgID == c.Org.ID && d.Name == in.Name {
			fail(w, 400, errors.New("you already added that domain"))
			return
		}
	}
	in.ID, in.OrgID = newID(), c.Org.ID
	s.st.Domains = append(s.st.Domains, &in)
	s.save()
	s.audit(c.Org.ID, c.Actor, "domain.add", in.Name)
	writeJSON(w, 200, in)
}

func (s *Server) deleteDomain(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	id := r.PathValue("id")
	s.mu.Lock()
	defer s.mu.Unlock()
	s.st.Domains = filter(s.st.Domains, func(d *model.Domain) bool { return !(d.ID == id && d.OrgID == c.Org.ID) })
	s.save()
	ok(w)
}

// checkDomain resolves the domain (and a probe subdomain) and compares with the edge's IPs.
func (s *Server) checkDomain(w http.ResponseWriter, r *http.Request, c *orgCtx) {
	s.mu.Lock()
	var d *model.Domain
	for _, x := range s.st.Domains {
		if x.ID == r.PathValue("id") && x.OrgID == c.Org.ID {
			cp := *x
			d = &cp
		}
	}
	var edgeIPs []string
	if d != nil {
		if e := s.findEdge(d.EdgeID); e != nil {
			edgeIPs = append(edgeIPs, e.IPs...)
		}
	}
	s.mu.Unlock()
	if d == nil {
		fail(w, 404, errors.New("no such domain"))
		return
	}
	want := map[string]bool{}
	for _, ip := range edgeIPs {
		want[ip] = true
	}
	if d.IP != "" {
		want[d.IP] = true
	}
	resolved, err := net.LookupHost(d.Name)
	if err != nil {
		writeJSON(w, 200, map[string]any{"resolved": []string{}, "matches": false, "error": "no DNS record found"})
		return
	}
	sort.Strings(resolved)
	matches := false
	for _, ip := range resolved {
		if want[ip] {
			matches = true
		}
	}
	writeJSON(w, 200, map[string]any{"resolved": resolved, "matches": matches})
}

// hostnameAllowed reports whether org owns a domain that covers host.
func (s *Server) hostnameAllowed(orgID, host string) bool {
	host = strings.TrimPrefix(host, "*.")
	for _, d := range s.st.Domains {
		if d.OrgID == orgID && (host == d.Name || strings.HasSuffix(host, "."+d.Name)) {
			return true
		}
	}
	return false
}