// mail-page-dev: the mail page, run locally to click through (issue 1859.5). It serves mesh-mail-web's own page
// handlers (internal/web, NewServer) on 127.0.0.1 only, over invented mail in two accounts and an in-memory
// mail reading; nothing reaches the mesh: no bus, no database, no Keycloak, no mail server, and nothing is
// written to disk. Sign-in is a stand-in that is always signed in, so every form works. It is not part of the
// module's build (module.json builds cmd/mesh-mail-web alone).
//
//	go run ./cmd/mail-page-dev [-addr 127.0.0.1:8463] [-now 2026-10-22T09:00:00+02:00]
package main

import (
	"errors"
	"flag"
	"fmt"
	"net"
	"net/http"
	"os"
	"time"

	"mesh-mail-web/internal/web"
)

// DefaultAddr is where the local run listens unless told another 127.0.0.1 address.
const DefaultAddr = "127.0.0.1:8463"

// localRun is a running local page.
type localRun struct {
	URL    string
	server *http.Server
	world  *world
}

func (l *localRun) Close() error { return l.server.Close() }

// newBundle is the page's Bundle over the world's stand-ins: every seat the page reaches is given, so nothing
// ever falls back to the bus.
func newBundle(w *world) *web.Bundle {
	r := w.read
	return &web.Bundle{
		Accounts:      w.accounts,
		Search:        w.search,
		Read:          w.readMail,
		Send:          w.send,
		SendStatus:    w.sendStatus,
		AccountBucket: w.bucket,
		MailEntries:   r.verb(r.entriesVerb),
		MailGroups:    r.verb(r.groupsVerb),
		MailStatus:    r.verb(r.statusVerb),
		MailCorrect:   r.verb(r.correctVerb),
		MailLessons:   r.verb(r.lessonsVerb),
		MailUndo:      r.verb(r.undoVerb),
		MailList:      r.verb(r.listVerb),
		MailHandle:    r.verb(r.act("handle")),
		MailUnhandle:  r.verb(r.act("unhandle")),
		MailRemind:    r.verb(r.act("remind")),
		MailRecord:    r.verb(r.recordVerb),
		ModesSetting: func() (map[string][]string, error) {
			return map[string][]string{"work": {"work"}, "personal": {"personal"}}, nil
		},
		Now: w.now,
	}
}

// start serves the page at addr, which must be a 127.0.0.1 address; now fixes "today" when not zero.
func start(addr string, now time.Time) (*localRun, error) {
	host, _, err := net.SplitHostPort(addr)
	if err != nil {
		return nil, fmt.Errorf("-addr %q is not host:port: %v", addr, err)
	}
	if host != "127.0.0.1" {
		return nil, errors.New("-addr must be a 127.0.0.1 address: the local run serves this machine alone")
	}
	clock := time.Now
	begin := time.Now()
	if !now.IsZero() {
		offset := now.Sub(begin)
		clock = func() time.Time { return time.Now().Add(offset) }
		begin = now
	}
	w := newWorld(begin, clock)

	// The stand-in sign-in: one session, made now, put on every request in place of whatever cookie the
	// browser carries — so every page and every form (their token is this session's) works, and no request
	// ever goes to sign in.
	sessions := web.NewSessions(clock)
	id, err := sessions.Create("operator (the local run's stand-in)")
	if err != nil {
		return nil, err
	}
	page := web.NewServer(host, &web.Auth{Sessions: sessions, Pending: web.NewPendingAuths(clock)}, newBundle(w))
	signedIn := http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
		req.Header.Del("Cookie")
		req.AddCookie(&http.Cookie{Name: web.SessionCookie, Value: id})
		page.ServeHTTP(rw, req)
	})

	ln, err := net.Listen("tcp", addr)
	if err != nil {
		return nil, err
	}
	srv := &http.Server{Handler: signedIn, ReadHeaderTimeout: 10 * time.Second}
	go func() { _ = srv.Serve(ln) }()
	return &localRun{URL: "http://" + ln.Addr().String() + "/", server: srv, world: w}, nil
}

func main() {
	addr := flag.String("addr", DefaultAddr, "where to listen: a 127.0.0.1 address only")
	nowFlag := flag.String("now", "", "fix today's time (RFC 3339, such as 2026-10-22T09:00:00+02:00), to show the list on that day")
	flag.Parse()
	var now time.Time
	if *nowFlag != "" {
		t, err := time.Parse(time.RFC3339, *nowFlag)
		if err != nil {
			fmt.Fprintf(os.Stderr, "mail-page-dev: -now %q is not RFC 3339: %v\n", *nowFlag, err)
			os.Exit(2)
		}
		now = t
	}
	run, err := start(*addr, now)
	if err != nil {
		fmt.Fprintf(os.Stderr, "mail-page-dev: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("mail-page-dev: the mail page with invented mail, at %s\n", run.URL)
	fmt.Println("mail-page-dev: it serves 127.0.0.1 alone; sign-in is a stand-in, always signed in")
	fmt.Println("mail-page-dev: nothing reaches the mesh: no bus, no database, no Keycloak, no mail; nothing is kept after it stops")
	if !now.IsZero() {
		fmt.Printf("mail-page-dev: today is fixed at %s\n", now.Format(time.RFC3339))
	}
	fmt.Println("mail-page-dev: Ctrl-C stops it")
	select {}
}