// Package live polls the game server through the WebPanelBridge plugin and caches the result, so
// page views never wait on RCON.
package live

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

	"git.zio.sh/cs2/simpleadmin-web/internal/rcon"
)

const (
	TeamSpectator = 1
	TeamT         = 2
	TeamCT        = 3
)

type Player struct {
	UserID  int    `json:"userid"`
	Name    string `json:"name"`
	SteamID string `json:"steamid"`
	Team    int    `json:"team"`
	Kills   int    `json:"kills"`
	Deaths  int    `json:"deaths"`
	Ping    int    `json:"ping"`
	Bot     bool   `json:"bot"`
}

type Status struct {
	Online     bool      `json:"online"`
	Error      string    `json:"-"`
	Hostname   string    `json:"hostname"`
	Map        string    `json:"map"`
	MaxPlayers int       `json:"maxPlayers"`
	ScoreT     int       `json:"scoreT"`
	ScoreCT    int       `json:"scoreCt"`
	Warmup     bool      `json:"warmup"`
	Players    []Player  `json:"players"`
	Updated    time.Time `json:"updated"`
}

// Humans returns the connected players that aren't bots.
func (s Status) Humans() []Player {
	out := make([]Player, 0, len(s.Players))
	for _, p := range s.Players {
		if !p.Bot {
			out = append(out, p)
		}
	}
	return out
}

// Find returns the online player with this SteamID64.
func (s Status) Find(steamid string) (Player, bool) {
	for _, p := range s.Players {
		if !p.Bot && p.SteamID == steamid {
			return p, true
		}
	}
	return Player{}, false
}

var errNoBridge = errors.New("WebPanelBridge didn't answer; is the plugin installed?")

// Parse reads css_webpanel_status output.
func Parse(out string) (Status, error) {
	var st Status
	gotServer, gotEnd := false, false
	for line := range strings.SplitSeq(out, "\n") {
		line = strings.TrimSpace(line)
		rest, ok := strings.CutPrefix(line, "wpb ")
		if !ok {
			continue
		}
		if rest == "end" {
			gotEnd = true
			continue
		}
		if !gotServer {
			var srv struct {
				V          int    `json:"v"`
				Hostname   string `json:"hostname"`
				Map        string `json:"map"`
				MaxPlayers int    `json:"maxPlayers"`
				ScoreT     int    `json:"scoreT"`
				ScoreCt    int    `json:"scoreCt"`
				Warmup     bool   `json:"warmup"`
			}
			if err := json.Unmarshal([]byte(rest), &srv); err != nil || srv.V != 1 {
				return st, errors.New("unrecognised WebPanelBridge output")
			}
			st.Hostname, st.Map, st.MaxPlayers = srv.Hostname, srv.Map, srv.MaxPlayers
			st.ScoreT, st.ScoreCT, st.Warmup = srv.ScoreT, srv.ScoreCt, srv.Warmup
			gotServer = true
			continue
		}
		var p Player
		if err := json.Unmarshal([]byte(rest), &p); err == nil {
			st.Players = append(st.Players, p)
		}
	}
	if !gotServer {
		return st, errNoBridge
	}
	if !gotEnd {
		return st, errors.New("WebPanelBridge output was cut off")
	}
	st.Online = true
	return st, nil
}

type Poller struct {
	rc       *rcon.Client
	interval time.Duration

	mu      sync.RWMutex
	current Status
}

func NewPoller(rc *rcon.Client, interval time.Duration) *Poller {
	return &Poller{rc: rc, interval: interval}
}

// Run polls until ctx is done.
func (p *Poller) Run(ctx context.Context) {
	t := time.NewTicker(p.interval)
	defer t.Stop()
	p.Refresh()
	for {
		select {
		case <-ctx.Done():
			return
		case <-t.C:
			p.Refresh()
		}
	}
}

// Refresh polls now. Actions call it so the next page load shows their effect.
func (p *Poller) Refresh() Status {
	out, err := p.rc.Exec("css_webpanel_status")
	var st Status
	if err == nil {
		st, err = Parse(out)
	}
	st.Updated = time.Now()
	if err != nil {
		st = Status{Error: err.Error(), Updated: st.Updated}
		// Log each new kind of failure once, so a wrong password or missing plugin shows up in the
		// log without repeating every few seconds. ErrDown only repeats the previous failure.
		p.mu.RLock()
		changed := p.current.Online || p.current.Updated.IsZero() || p.current.Error != st.Error
		p.mu.RUnlock()
		if changed && !errors.Is(err, rcon.ErrDown) {
			slog.Warn("game server status unavailable", "err", err)
		}
	}
	p.mu.Lock()
	if st.Online && !p.current.Online && !p.current.Updated.IsZero() {
		slog.Info("game server status available again")
	}
	// While backing off, keep the underlying error rather than "retrying shortly".
	if errors.Is(err, rcon.ErrDown) && p.current.Error != "" {
		st.Error = p.current.Error
	}
	p.current = st
	p.mu.Unlock()
	return st
}

func (p *Poller) Current() Status {
	p.mu.RLock()
	defer p.mu.RUnlock()
	return p.current
}