package api

// Guest logins: a temporary account for handing to somebody you want to show around. It is
// an ordinary account with a clock on it — every tab, every action, on this machine and on
// every machine this hub manages — that stops working at its expiry (half an hour by
// default) or the moment it is revoked.
//
// Deliberately not a reduced account: Mitchell, 2026-09-27, replacing a read-only version
// built the same day. He gives these to people he trusts and revokes them otherwise, and a
// console with half its buttons missing is not the console he wanted to show off. What that
// means in practice: a guest has the Terminal tab, which is a shell as the user the daemon
// runs as — root on every host here — and can make an account or a token of its own that
// outlives the guest login.

import (
	"encoding/json"
	"io"
	"log"
	"net/http"
	"strings"
	"time"

	"hamlab/internal/auth"
	"hamlab/internal/config"
	"hamlab/internal/store"
)

const (
	guestPrefix     = "guest-"
	guestTTLDefault = 30 * time.Minute
	guestTTLMax     = 24 * time.Hour
	guestReapEvery  = time.Minute
)

// ---- the accounts themselves ----

func (s *Server) listGuests(w http.ResponseWriter, r *http.Request) {
	now := time.Now()
	counts := s.sessions.Count()
	out := []map[string]any{}
	s.cfg.View(func(c *config.Config) {
		for _, u := range c.Users {
			if !u.Guest || u.Expired(now) {
				continue
			}
			out = append(out, map[string]any{
				"name": u.Name, "created": u.Created, "expires": u.Expires,
				"issued_by": u.IssuedBy, "sessions": counts[u.Name], "used": !u.LastSeen.IsZero(),
			})
		}
	})
	jsonOK(w, 200, out)
}

// addGuest makes a guest login and hands back its password — the only time it is ever
// readable, here as everywhere else a password is generated.
func (s *Server) addGuest(w http.ResponseWriter, r *http.Request) {
	me := actorOf(r)
	var body struct {
		Minutes int `json:"minutes"`
	}
	_ = json.NewDecoder(io.LimitReader(r.Body, 4096)).Decode(&body)
	ttl := guestTTLDefault
	if body.Minutes > 0 {
		ttl = time.Duration(body.Minutes) * time.Minute
	}
	if ttl > guestTTLMax {
		jsonErr(w, 400, "a guest login lasts at most 24 hours")
		return
	}
	pw, err := auth.GuestPassword()
	if err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	hash, err := auth.HashPassword(pw)
	if err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	var name string
	for try := 0; try < 8 && name == ""; try++ {
		suffix, err := auth.GuestSuffix()
		if err != nil {
			jsonErr(w, 500, err.Error())
			return
		}
		candidate := guestPrefix + suffix
		s.cfg.View(func(c *config.Config) {
			if _, taken := c.User(candidate); !taken {
				name = candidate
			}
		})
	}
	if name == "" {
		jsonErr(w, 500, "could not find a free guest name")
		return
	}
	now := time.Now()
	expires := now.Add(ttl)
	if err := s.cfg.Update(func(c *config.Config) {
		c.Users = append(c.Users, config.User{Name: name, Hash: hash, Created: now, Guest: true, Expires: expires, IssuedBy: me.User})
	}); err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	log.Printf("guest login %q issued until %s (by %s)", name, expires.Format(time.RFC3339), clientIP(r))
	jsonOK(w, 200, map[string]any{"name": name, "password": pw, "expires": expires, "minutes": int(ttl.Minutes())})
}

// revokeGuest ends a guest login now. No password: it only ever takes access away, and the
// whole point of the thing is that ending it is one tap.
func (s *Server) revokeGuest(w http.ResponseWriter, r *http.Request) {
	name := r.PathValue("name")
	found := false
	if err := s.cfg.Update(func(c *config.Config) {
		kept := c.Users[:0]
		for _, u := range c.Users {
			if u.Name == name && u.Guest {
				found = true
				continue
			}
			kept = append(kept, u)
		}
		c.Users = kept
	}); err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	if !found {
		jsonErr(w, 404, "no such guest login")
		return
	}
	s.forgetGuest(name)
	log.Printf("guest login %q revoked (by %s)", name, clientIP(r))
	w.WriteHeader(204)
}

// forgetGuest signs a guest out everywhere and drops the look they left behind.
func (s *Server) forgetGuest(name string) {
	s.sessions.RevokeUser(name)
	_ = s.store.Update(func(st *store.State) { delete(st.Users, name) })
}

// watchGuests clears out guest logins whose time is up. Expiry is enforced on every request
// as well — this is what keeps the config file from collecting them, and what signs a guest
// out of a console they left open rather than waiting for their next click.
func (s *Server) watchGuests() {
	for {
		s.reapGuests()
		time.Sleep(guestReapEvery)
	}
}

func (s *Server) reapGuests() {
	now := time.Now()
	var gone []string
	var have bool
	s.cfg.View(func(c *config.Config) {
		for _, u := range c.Users {
			if u.Guest {
				have = true
				if u.Expired(now) {
					gone = append(gone, u.Name)
				}
			}
		}
	})
	if !have || len(gone) == 0 {
		return
	}
	expired := map[string]bool{}
	for _, n := range gone {
		expired[n] = true
	}
	if err := s.cfg.Update(func(c *config.Config) {
		kept := c.Users[:0]
		for _, u := range c.Users {
			if expired[u.Name] {
				continue
			}
			kept = append(kept, u)
		}
		c.Users = kept
	}); err != nil {
		log.Printf("guests: %v", err)
		return
	}
	for _, n := range gone {
		s.forgetGuest(n)
	}
	log.Printf("guest login(s) expired: %s", strings.Join(gone, ", "))
}