package web

import (
	"fmt"
	"log/slog"
	"net/http"
	"time"

	"pete/internal/storage"
)

// "While you were away" — the one panel on the site that is about the reader.
//
// Everything else in the adventure section is the realm's news: the board, the
// Siege, the standings. This is the owner's own adventurer, and only what has
// happened to them since they last looked. It pairs with W6's push alerts and
// covers the gap those deliberately leave: the alerts are four opt-in categories
// chosen for being worth interrupting somebody over, while this catches
// everything, for people who would rather not be interrupted at all.
//
// It renders on /adventure page 1 only. The panel is present tense and page 2 of
// an archive is not where anybody looks for what just happened, which is the same
// rule the roster and the Siege strip already follow.

// awayCap bounds the panel. Six lines is a glance; a longer list is the trail on
// the adventurer's own page, which is where the "all of it" link goes.
const awayCap = 6

// awayView is the panel. Has is false in every case where there is nothing
// honest to show — not signed in, no adventurer, first ever visit, or simply
// nothing new — and the template renders nothing at all rather than an empty box
// announcing that nothing happened.
type awayView struct {
	Has   bool
	Name  string // the reader's own character
	Since string // "3 hours", "2 days" — how long they were gone
	Lines []awayLine
	// HasMore says there is more than the cap, without saying how much more. The
	// window query reads one row past the cap to learn this; an exact count would
	// need a second query over the same window to tell somebody a number they are
	// about to click past anyway.
	HasMore bool
	Token   string // their adventurer page, where the rest of the trail is
}

// awayLine is one thing that happened, in the trail's own shape. Built from the
// fact rather than from the dispatch headline for the same reason buildTimeline
// is: a headline is a news sentence written to be shouted once, and six of them
// stacked in a panel read as shouting.
type awayLine struct {
	Emoji     string
	Label     string
	Line      string
	When      string // relative: this panel is about recency
	Permalink string
	Notable   bool
}

// awayPanel builds the panel for whoever is asking, and stamps their visit.
//
// The stamp is written even when the panel comes back empty — even for a signed-in
// user with no adventurer at all — and that is deliberate: a clock that only
// advances when there is something to show would hand somebody their entire
// backlog on the day they finally rolled a character.
func (s *Server) awayPanel(r *http.Request) awayView {
	if s.auth == nil {
		return awayView{}
	}
	u := s.auth.userFromRequest(r)
	if u == nil {
		return awayView{}
	}

	now := time.Now().Unix()
	from, first, err := storage.AdvVisitWindow(u.Sub, now)
	if err != nil {
		slog.Error("away: visit clock failed", "sub", u.Sub, "err", err)
		return awayView{}
	}
	if first {
		// Never seen before. Their history is not news to them, and a first visit
		// greeted by every death their character ever suffered is a worse welcome
		// than no panel at all.
		return awayView{}
	}

	// The ownership join, re-read on every request rather than cached anywhere —
	// same discipline as the alert sender and the run report link. It fails closed
	// on an opt-out and on a player gogobee has stopped pushing, both of which mean
	// Pete cannot honestly say which adventurer is this reader's.
	lp := buyerLocalpart(u)
	if lp == "" {
		return awayView{}
	}
	name, ok := storage.AdvCharacterForOwner(lp)
	if !ok {
		return awayView{}
	}

	// One extra row is fetched past the cap purely to answer "is there more",
	// without a second COUNT query over the same window.
	events, err := storage.EventsBySubjectSince(name, from, awayCap+1)
	if err != nil {
		slog.Error("away: dispatch lookup failed", "subject", name, "err", err)
		return awayView{}
	}
	if len(events) == 0 {
		return awayView{}
	}

	v := awayView{Has: true, Name: name, Since: awaySince(now - from)}
	if token, ok := storage.SelfToken(lp); ok {
		v.Token = token
	}
	if len(events) > awayCap {
		v.HasMore = true
		events = events[:awayCap]
	}
	for _, e := range events {
		label, emoji := advEventMeta(e.EventType)
		v.Lines = append(v.Lines, awayLine{
			Emoji:     emoji,
			Label:     label,
			Line:      timelineLine(name, e),
			When:      awayAgo(now - e.OccurredAt),
			Permalink: s.advPermalink(e.GUID),
			Notable: e.EventType == "boss_first" || e.EventType == "zone_first" ||
				e.EventType == "death",
		})
	}
	return v
}

// awaySince phrases the gap the panel covers. Rounded down, and it never claims
// less than an hour: the window is at least one session gap wide, and "since 34
// minutes ago" is a precision the clock behind it does not have.
func awaySince(secs int64) string {
	switch d := time.Duration(secs) * time.Second; {
	case d < 2*time.Hour:
		return "an hour"
	case d < 48*time.Hour:
		return fmt.Sprintf("%d hours", int(d.Hours()))
	case d < 14*24*time.Hour:
		return fmt.Sprintf("%d days", int(d.Hours())/24)
	default:
		return "a while"
	}
}

// awayAgo is a compact relative stamp for one line. Deliberately not the trail's
// "Jan 2, 2006": everything in this panel is recent by construction, and a date
// on it would make the reader do the subtraction themselves.
func awayAgo(secs int64) string {
	switch d := time.Duration(secs) * time.Second; {
	case d < time.Minute:
		return "just now"
	case d < time.Hour:
		return fmt.Sprintf("%dm ago", int(d.Minutes()))
	case d < 24*time.Hour:
		return fmt.Sprintf("%dh ago", int(d.Hours()))
	default:
		return fmt.Sprintf("%dd ago", int(d.Hours())/24)
	}
}