package main

import (
	"context"
	"encoding/json"
	"errors"
	"log/slog"
	"net/http"
	"sync"
	"time"

	"nhooyr.io/websocket"
	"nhooyr.io/websocket/wsjson"

	"git.sunturtle.xyz/studio/shotgun/game"
	"git.sunturtle.xyz/studio/shotgun/lobby"
	"git.sunturtle.xyz/studio/shotgun/player"
	"git.sunturtle.xyz/studio/shotgun/serve"
)

type Server struct {
	l *lobby.Lobby

	creds    db
	sessions db

	mu sync.Mutex
	pp map[player.ID]*websocket.Conn
}

type db interface {
	player.RowQuerier
	player.Execer
}

type person struct {
	conn *websocket.Conn
	id   player.ID
}

func (s *Server) person(p player.ID) person {
	s.mu.Lock()
	defer s.mu.Unlock()
	return person{conn: s.pp[p], id: p}
}

func (s *Server) accept(w http.ResponseWriter, r *http.Request, p player.ID) (person, error) {
	conn, err := websocket.Accept(w, r, nil)
	if err != nil {
		return person{}, err
	}
	slog.Debug("upgraded", "player", p)
	s.mu.Lock()
	defer s.mu.Unlock()
	s.pp[p] = conn
	return person{conn: conn, id: p}, nil
}

func (s *Server) left(p player.ID) {
	s.mu.Lock()
	// NOTE(zeph): neither map index nor map delete can panic, so this critical
	// section does not need a defer
	c := s.pp[p]
	delete(s.pp, p)
	s.mu.Unlock()
	if c != nil {
		// We don't care about the error here since the connection is leaving.
		// It's probably already closed anyway.
		slog.Debug("leaving", "player", p)
		c.Close(websocket.StatusNormalClosure, "bye")
	}
}

func (s *Server) Register(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	slog := slog.With(
		slog.String("remote", r.RemoteAddr),
		slog.String("forwarded-for", r.Header.Get("X-Forwarded-For")),
		slog.String("user-agent", r.UserAgent()),
	)
	if err := r.ParseForm(); err != nil {
		slog.WarnContext(ctx, "error parsing form on register", "err", err.Error())
		http.Error(w, "what", http.StatusBadRequest)
		return
	}
	user, pass := r.PostFormValue("user"), r.PostFormValue("pass")
	if user == "" || pass == "" {
		slog.WarnContext(ctx, "missing user or pass on register")
		http.Error(w, "missing credentials", http.StatusBadRequest)
		return
	}
	err := player.Register(ctx, s.creds, user, pass)
	if err != nil {
		slog.ErrorContext(ctx, "registration failed", "err", err.Error())
		http.Error(w, "something went wrong, maybe someone already has that username, idk", http.StatusInternalServerError)
		return
	}
	p, err := player.Login(ctx, s.creds, user, pass)
	if err != nil {
		slog.ErrorContext(ctx, "login failed", "err", err.Error())
		http.Error(w, "no", http.StatusUnauthorized)
		return
	}
	id, err := player.StartSession(ctx, s.sessions, p, time.Now())
	if err != nil {
		slog.ErrorContext(ctx, "failed to create session", "player", p, "err", err.Error())
		http.Error(w, "something went wrong", http.StatusInternalServerError)
		return
	}
	serve.SetSession(w, id)
	http.Redirect(w, r, "/", http.StatusSeeOther)
	slog.InfoContext(ctx, "registered", "user", user)
}

func (s *Server) Login(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	slog := slog.With(
		slog.String("remote", r.RemoteAddr),
		slog.String("forwarded-for", r.Header.Get("X-Forwarded-For")),
		slog.String("user-agent", r.UserAgent()),
	)
	if err := r.ParseForm(); err != nil {
		slog.WarnContext(ctx, "error parsing form on login", "err", err.Error())
		http.Error(w, "what", http.StatusBadRequest)
		return
	}
	user, pass := r.PostFormValue("user"), r.PostFormValue("pass")
	if user == "" || pass == "" {
		slog.WarnContext(ctx, "missing user or pass on login")
		http.Error(w, "missing credentials", http.StatusBadRequest)
		return
	}
	p, err := player.Login(ctx, s.creds, user, pass)
	if err != nil {
		slog.ErrorContext(ctx, "login failed", "err", err.Error())
		http.Error(w, "no", http.StatusUnauthorized)
		return
	}
	id, err := player.StartSession(ctx, s.sessions, p, time.Now())
	if err != nil {
		slog.ErrorContext(ctx, "failed to create session", "player", p, "err", err.Error())
		http.Error(w, "something went wrong", http.StatusInternalServerError)
		return
	}
	serve.SetSession(w, id)
	http.Redirect(w, r, "/", http.StatusSeeOther)
	slog.InfoContext(ctx, "logged in", "player", p, "id", id)
}

func (s *Server) Logout(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	slog := slog.With(
		slog.String("remote", r.RemoteAddr),
		slog.String("forwarded-for", r.Header.Get("X-Forwarded-For")),
		slog.String("user-agent", r.UserAgent()),
	)
	id := serve.ReqSession(ctx)
	if id == (player.Session{}) {
		slog.WarnContext(ctx, "no session on logout")
		http.Error(w, "what", http.StatusUnauthorized)
		panic("unreachable")
	}
	err := player.Logout(ctx, s.sessions, id)
	if err != nil {
		slog.ErrorContext(ctx, "logout failed", "err", err.Error())
		http.Error(w, "something went wrong", http.StatusInternalServerError)
		return
	}
	serve.RemoveSession(w)
	slog.InfoContext(ctx, "logged out", "session", id)
	http.Redirect(w, r, "/", http.StatusSeeOther)
}

func (s *Server) Me(w http.ResponseWriter, r *http.Request) {
	id := serve.ReqPlayer(r.Context())
	if id == (player.ID{}) {
		panic("missing player ID")
	}
	q := struct {
		ID player.ID `json:"id"`
	}{id}
	json.NewEncoder(w).Encode(q)
}

// Queue connects players to games. The connection immediately upgrades.
// This handler MUST be wrapped in [serve.WithPlayerID].
func (s *Server) Queue(w http.ResponseWriter, r *http.Request) {
	p := serve.ReqPlayer(r.Context())
	person, err := s.accept(w, r, p)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	s.joinAndServe(person)
}

func (s *Server) joinAndServe(p person) {
	slog.Debug("joining", "player", p.id)
	ctx, stop := context.WithTimeoutCause(context.Background(), 10*time.Minute, errQueueEmpty)
	go func() {
		for {
			_, _, err := p.conn.Read(context.Background())
			if err != nil || ctx.Err() != nil {
				return
			}
		}
	}()
	id, chall, deal := s.l.Queue(ctx, p.id)
	stop()
	if id == (lobby.GameID{}) {
		// Context canceled.
		p.conn.Close(websocket.StatusTryAgainLater, "sorry, queue is empty...")
		return
	}
	if deal {
		g := game.New(p.id, chall)
		other := s.person(chall)
		// TODO(zeph): save the game state s.t. we can provide a join channel
		go gameActor(context.TODO(), g, p, other, nil)
	}
	// Reply with the game ID so they can share.
	r := serve.GameStart{
		ID:     id,
		Dealer: deal,
	}
	if err := wsjson.Write(context.TODO(), p.conn, r); err != nil {
		slog.WarnContext(ctx, "got a game but player dropped", "game", id, "player", p.id)
		s.left(p.id)
		return
	}
}

var errQueueEmpty = errors.New("sorry, queue is empty")