package web

import (
	"context"
	"log/slog"
	"net/http"
	"slices"
	"strings"
	"sync"
	"time"

	"git.zio.sh/cs2/simpleadmin-web/internal/live"
	"git.zio.sh/cs2/simpleadmin-web/internal/playtime"
	"git.zio.sh/cs2/simpleadmin-web/internal/steam"
)

// PlaytimeHistory (plugins/PlaytimeHistory in the cs2 repo) records who played when, in its own
// database (SAW_PT_DSN). Without that database, or its tables, nothing about playtime shows
// anywhere. With tables but nothing recorded yet, only staff see that it's there.
//
// Anyone sees playtime, stats and maps. Staff with playtimeStaffPerm also see who's on with their
// location, staff activity, disconnect reasons, countries, and a player's names, sessions and ping:
// on the staff panel's Playtime page, and on the public site when they're signed in.

const playtimePlugin = "PlaytimeHistory"

// playtimeStaffPerm matches PlaytimeHistory's own default for looking up other players.
const playtimeStaffPerm = "@css/generic"

// Playtime states for /api/me.
const (
	ptOff   = ""      // not configured, the tables are missing, or the database is down
	ptEmpty = "empty" // the tables are there, but nothing's recorded yet
	ptOn    = "on"
)

type ptCache struct {
	pt  *playtime.Store
	ttl time.Duration

	mu        sync.Mutex
	state     string
	fetched   time.Time
	logged    string // the last state or error logged, so a down database logs once
	overviews map[string]ptOverview
}

type ptOverview struct {
	at   time.Time
	view playtime.Overview
}

func (c *ptCache) get(ctx context.Context) string {
	if c == nil {
		return ptOff
	}
	c.mu.Lock()
	defer c.mu.Unlock()
	if !c.fetched.IsZero() && time.Since(c.fetched) < c.ttl {
		return c.state
	}
	tables, data, err := c.pt.State(ctx)
	state, note := ptOff, ""
	switch {
	case err != nil:
		note = "PlaytimeHistory's database isn't answering; playtime is hidden: " + err.Error()
	case !tables:
		note = "PlaytimeHistory's tables aren't in its database; playtime is hidden"
	case !data:
		state, note = ptEmpty, "PlaytimeHistory hasn't recorded anything yet"
	default:
		state, note = ptOn, "PlaytimeHistory found"
	}
	if note != c.logged {
		slog.Info("playtime", "state", state, "note", note)
		c.logged = note
	}
	c.state, c.fetched = state, time.Now()
	return state
}

// overview caches the public page per time zone for a minute: it's the heaviest query here.
func (c *ptCache) overview(ctx context.Context, loc *time.Location) (playtime.Overview, error) {
	c.mu.Lock()
	if o, ok := c.overviews[loc.String()]; ok && time.Since(o.at) < c.ttl {
		c.mu.Unlock()
		return o.view, nil
	}
	c.mu.Unlock()
	v, err := c.pt.Overview(ctx, time.Now(), loc)
	if err != nil {
		return v, err
	}
	c.mu.Lock()
	if c.overviews == nil || len(c.overviews) > 64 {
		c.overviews = map[string]ptOverview{}
	}
	c.overviews[loc.String()] = ptOverview{at: time.Now(), view: v}
	c.mu.Unlock()
	return v, nil
}

func (s *Server) ptState(ctx context.Context) string { return s.ptc.get(ctx) }

// ptStaff is whether this viewer may see the staff-only playtime figures.
func (s *Server) ptStaff(ctx context.Context, id *Identity) bool {
	return id != nil && id.Has(playtimeStaffPerm) && s.ptState(ctx) != ptOff
}

// viewerZone is the browser's time zone (?tz=Europe/London), for days and hours of the day.
func viewerZone(r *http.Request) *time.Location {
	name := r.URL.Query().Get("tz")
	if name == "" || len(name) > 64 || strings.Contains(name, "..") {
		return time.UTC
	}
	loc, err := time.LoadLocation(name)
	if err != nil {
		return time.UTC
	}
	return loc
}

// periodSince reads ?period=7d|30d|all; all is nil.
func periodSince(r *http.Request, allowAll bool) (string, *time.Time) {
	return periodParam(r.URL.Query().Get("period"), allowAll)
}

// periodParam turns 7d, 30d or all into when it starts; all is nil. Anything else is 7d.
func periodParam(p string, allowAll bool) (string, *time.Time) {
	now := time.Now()
	switch {
	case p == "30d":
		t := now.Add(-30 * 24 * time.Hour)
		return p, &t
	case p == "all" && allowAll:
		return p, nil
	default:
		t := now.Add(-7 * 24 * time.Hour)
		return "7d", &t
	}
}

type leaderView struct {
	playtime.Leader
	Rank *rankView `json:"rank,omitempty"`
}

// publicPlaytime is the public Playtime page: ?period= for the leaderboard, ?tz= for the charts.
func (s *Server) publicPlaytime(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	if s.ptState(ctx) != ptOn {
		fail(w, http.StatusNotFound, "Playtime isn't being recorded.")
		return
	}
	o, err := s.ptc.overview(ctx, viewerZone(r))
	if err != nil {
		internal(w, r, err)
		return
	}
	period, since := periodSince(r, true)
	leaders, err := s.pt.Leaders(ctx, since, 10)
	if err != nil {
		internal(w, r, err)
		return
	}
	x, err := s.staffIdx(ctx)
	if err != nil {
		internal(w, r, err)
		return
	}
	lv := make([]leaderView, 0, len(leaders))
	for _, l := range leaders {
		lv = append(lv, leaderView{Leader: l, Rank: s.rankOf(x, l.SteamID)})
	}
	resp := map[string]any{"overview": o, "period": period, "leaders": lv}
	// Records (?records=7d|30d|all) need pt_events, from PlaytimeHistory 0.2.0.
	if s.pt.HasEvents() {
		rp, rsince := periodParam(r.URL.Query().Get("records"), true)
		rec, err := s.pt.Records(ctx, rsince, 5)
		if err != nil {
			internal(w, r, err)
			return
		}
		resp["records"], resp["recordsPeriod"] = rec, rp
	}
	writeJSON(w, http.StatusOK, resp)
}

type onlineView struct {
	SteamID string    `json:"steamid"`
	Name    string    `json:"name"`
	Rank    *rankView `json:"rank,omitempty"`
	Team    int       `json:"team"`
	Ping    int       `json:"ping"`
	playtime.Online
}

type activityView struct {
	SteamID string    `json:"steamid"`
	Name    string    `json:"name"`
	Rank    *rankView `json:"rank,omitempty"`
	Online  bool      `json:"online"`
	playtime.Activity
}

// adminPlaytime is the staff-only half of the Playtime page (?period=7d|30d for staff activity).
// The public half comes from publicPlaytime.
func (s *Server) adminPlaytime(w http.ResponseWriter, r *http.Request, id *Identity, x *staffIndex) {
	ctx := r.Context()
	if !id.Has(playtimeStaffPerm) {
		fail(w, http.StatusForbidden, "You need "+playtimeStaffPerm+" to see staff playtime.")
		return
	}
	state := s.ptState(ctx)
	if state == ptOff {
		fail(w, http.StatusNotFound, "The panel can't reach PlaytimeHistory's database, or its tables aren't there.")
		return
	}
	now := time.Now()
	month := now.Add(-30 * 24 * time.Hour)
	st := s.poll.Current()

	// Who's on comes from the live status, which leaves out admins hidden with css_hide.
	humans := st.Humans()
	ids := make([]uint64, 0, len(humans))
	for _, p := range humans {
		if n, err := playtime.ParseID(p.SteamID); err == nil {
			ids = append(ids, n)
		}
	}
	open, err := s.pt.Online(ctx, ids)
	if err != nil {
		internal(w, r, err)
		return
	}
	online := make([]onlineView, 0, len(humans))
	for _, p := range humans {
		online = append(online, onlineView{SteamID: p.SteamID, Name: p.Name, Rank: s.rankOf(x, p.SteamID),
			Team: p.Team, Ping: p.Ping, Online: open[p.SteamID]})
	}
	// Longest on first; anyone without a recorded session last.
	slices.SortStableFunc(online, func(a, b onlineView) int {
		switch {
		case a.Since == nil || b.Since == nil:
			return boolInt(a.Since == nil) - boolInt(b.Since == nil)
		default:
			return a.Since.Compare(*b.Since)
		}
	})

	period, since := periodSince(r, false)
	var staffIDs []uint64
	for _, a := range x.admins {
		if n, err := playtime.ParseID(a.SteamID); err == nil && s.isStaff(x, a.SteamID) {
			staffIDs = append(staffIDs, n)
		}
	}
	act, err := s.pt.Activity(ctx, staffIDs, *since)
	if err != nil {
		internal(w, r, err)
		return
	}
	staffList := []activityView{}
	for _, a := range x.admins {
		if !s.isStaff(x, a.SteamID) {
			continue
		}
		_, on := st.Find(a.SteamID)
		staffList = append(staffList, activityView{SteamID: a.SteamID, Name: a.Name, Rank: s.rankOf(x, a.SteamID),
			Online: on, Activity: act[a.SteamID]})
	}
	slices.SortStableFunc(staffList, func(a, b activityView) int {
		if a.Hours != b.Hours {
			if a.Hours > b.Hours {
				return -1
			}
			return 1
		}
		return x.groupIndex(x.primaryGroup(x.bySteam[a.SteamID])) - x.groupIndex(x.primaryGroup(x.bySteam[b.SteamID]))
	})

	reasons, err := s.pt.Reasons(ctx, month)
	if err != nil {
		internal(w, r, err)
		return
	}
	countries, err := s.pt.Countries(ctx)
	if err != nil {
		internal(w, r, err)
		return
	}
	ends, err := s.pt.EndKinds(ctx, month)
	if err != nil {
		internal(w, r, err)
		return
	}
	resp := map[string]any{
		"state": state, "period": period, "online": online, "staff": staffList,
		"reasons": reasons, "countries": countries,
		"endKinds": map[string]int{
			"open": ends[playtime.EndOpen], "disconnect": ends[playtime.EndDisconnect], "mapChange": ends[playtime.EndMapChange],
			"unload": ends[playtime.EndUnload], "stale": ends[playtime.EndStale],
		},
	}
	// The recorder's own status can carry database errors, so it's for Root, as css_pt_status is.
	if id.Has("@css/root") {
		resp["recorder"] = s.ptRecorder()
	}
	writeJSON(w, http.StatusOK, resp)
}

func boolInt(b bool) int {
	if b {
		return 1
	}
	return 0
}

// ptRecorder is whether PlaytimeHistory is loaded and, if it is, what css_pt_status says.
func (s *Server) ptRecorder() map[string]any {
	state, version := s.poll.Plugin(playtimePlugin)
	out := map[string]any{"plugin": state, "version": version, "lines": []string{}}
	if state != live.PluginLoaded {
		return out
	}
	res, err := s.rc.Exec("css_pt_status")
	if err != nil {
		return out
	}
	var lines []string
	for _, l := range strings.Split(res, "\n") {
		if l = strings.TrimSpace(l); strings.HasPrefix(l, "[Playtime] ") {
			lines = append(lines, strings.TrimPrefix(l, "[Playtime] "))
		}
	}
	if lines != nil {
		out["lines"] = lines
	}
	return out
}

// playerPlaytime is the Playtime part of a player's drawer, or nil when playtime isn't shown.
// Errors are logged and leave it out: playtime is extra, never worth failing the drawer.
func (s *Server) playerPlaytime(r *http.Request, steamid string, staff bool) map[string]any {
	ctx := r.Context()
	state := s.ptState(ctx)
	if state == ptOff || (state == ptEmpty && !staff) || !steam.ValidID(steamid) {
		return nil
	}
	n, err := playtime.ParseID(steamid)
	if err != nil {
		return nil
	}
	now := time.Now()
	p, err := s.pt.Player(ctx, n, now, viewerZone(r))
	if err != nil {
		slog.Warn("playtime for a player", "steamid", steamid, "err", err)
		return nil
	}
	out := map[string]any{"player": p}
	if staff {
		extra, err := s.pt.PlayerStaff(ctx, n)
		if err != nil {
			slog.Warn("staff playtime for a player", "steamid", steamid, "err", err)
			return out
		}
		out["staff"] = extra
	}
	return out
}