package main

// How the five settings of ADR 0329 reach the profile (§7–§9).
//
// Identities, calendars, address books and tags are matched as accounts are (ADR 0317): an entry the module
// recorded on this node is kept by its recorded key; else an entry under the module's own key is its creation;
// else a key a node's layer names is adopted when the profile holds it and it matches; else the profile's
// entries that match (an identity by its address within its account, a calendar and an address book by their
// address, a tag by its key): one is adopted, none means the entry is created under the module's own key, more
// than one is refused with the remedy. Their declared fields are written into the user.js the module places,
// where they win at every start. An entry leaving the setting releases what was adopted and removes the
// preferences of what was created; never a calendar's events, an address book's contacts or a cache.
//
// What Betterbird rewrites itself is written only while it does not run (§9): the lists in prefs.js (an adopted
// account's identities, the calendars' order) and each account's msgFilterRules.dat. Until then the module's
// check counts, per kind, the changes that wait.

import (
	"bufio"
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
)

// configRecordFile is where the module records, per profile, what it adopted or created of the five kinds and
// which filter files it wrote (ADR 0329 §7, §8, ADR 0317 §3).
const configRecordFile = ".config/betterbird/configuration-record.json"

// resolvedEntry is one declared entry as it resolved on this node.
type resolvedEntry struct {
	Kind string `json:"kind"`
	Name string `json:"name"`
	How  string `json:"how"`
	Key  string `json:"key,omitempty"`
	Why  string `json:"why,omitempty"`
}

type recordedEntry struct {
	How string `json:"how"`
	Key string `json:"key"`
}

// filterRecord is what the module did with one account's filter file on a profile.
type filterRecord struct {
	// File is the account's filter file as the module last wrote it, and Kept the file it replaced at its first write.
	File string `json:"file"`
	Kept string `json:"kept,omitempty"`
	// Released says the account left the setting filters: the module no longer writes its file (§8).
	Released bool `json:"released,omitempty"`
}

type configRecord struct {
	Entries map[string]map[string]recordedEntry `json:"entries,omitempty"`
	Filters map[string]filterRecord             `json:"filters,omitempty"`
}

func (m *Machine) readConfigRecord(profileDir string) configRecord {
	all := map[string]configRecord{}
	if raw, err := readBounded(m.home(configRecordFile)); err == nil {
		_ = json.Unmarshal(raw, &all)
	}
	r := all[profileDir]
	if r.Entries == nil {
		r.Entries = map[string]map[string]recordedEntry{}
	}
	if r.Filters == nil {
		r.Filters = map[string]filterRecord{}
	}
	return r
}

func (m *Machine) writeConfigRecord(profileDir string, r configRecord) error {
	all := map[string]configRecord{}
	if raw, err := readBounded(m.home(configRecordFile)); err == nil {
		_ = json.Unmarshal(raw, &all)
	}
	all[profileDir] = r
	body, err := json.MarshalIndent(all, "", "  ")
	if err != nil {
		return err
	}
	return writeAtomic(m.home(configRecordFile), append(body, '\n'), 0o600)
}

// writeAtomic writes a file beside itself and renames it into place.
func writeAtomic(path string, data []byte, mode os.FileMode) error {
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return err
	}
	tmp := path + ".mesh-new"
	if err := writeSynced(tmp, data, mode); err != nil {
		os.Remove(tmp)
		return err
	}
	if err := os.Rename(tmp, path); err != nil {
		os.Remove(tmp)
		return err
	}
	return nil
}

// The module's own keys for what it creates: each names the entry.
func ownIdentityKey(name string) string { return "ident_mesh_" + name }
func ownCalendarKey(name string) string { return "mesh_" + name }
func ownBookKey(name string) string     { return "mesh_" + name }

var (
	ownIdentity = regexp.MustCompile(`^ident_mesh_[a-z][a-z0-9]{0,30}$`)
	ownMeshKey  = regexp.MustCompile(`^mesh_[a-z][a-z0-9]{0,30}$`)
)

// configPlan is what an apply does for the five kinds on this profile.
type configPlan struct {
	Entries []resolvedEntry
	// lines are the user.js statements, a comment before each entry's.
	lines []string
	// identityLists are, per adopted account key, the identity keys of the module's own it wants in its list.
	identityLists map[string][]string
	// calendarOrder are the calendar keys the module created, for calendar.list.sortOrder.
	calendarOrder []string
	// removals are the preference prefixes of what the module created and the setting no longer holds.
	removals []string
	filters  []filterPlan
	// released are the accounts that left the setting filters since the module last wrote their file.
	released []string
	record   configRecord
	problem  string
}

// filterPlan is one declared account's filter file on this node.
type filterPlan struct {
	Account string `json:"account"`
	File    string `json:"file,omitempty"`
	// Waiting says why the file cannot be written yet, when it cannot.
	Waiting string `json:"waiting,omitempty"`
	Refused string `json:"refused,omitempty"`
	want    string
	have    string
	exists  bool
	path    string
}

func (p filterPlan) changes() bool { return p.Refused == "" && p.path != "" && p.want != p.have }

// planConfiguration resolves every declared entry against the profile and says what an apply writes.
func (m *Machine) planConfiguration(profile Profile, c Configuration, accounts map[string]Account,
	ra []resolvedAccount, prefs map[string]string) configPlan {
	rec := m.readConfigRecord(profile.Dir)
	plan := configPlan{identityLists: map[string][]string{},
		record: configRecord{Entries: map[string]map[string]recordedEntry{}, Filters: map[string]filterRecord{}}}
	byName := map[string]resolvedAccount{}
	for _, r := range ra {
		byName[r.name] = r
	}
	have := profileAccounts(prefs)
	listOfAccount := map[string][]string{}
	for _, a := range have {
		listOfAccount[a.Key] = a.Identities
	}
	identityKeyOf := map[string]string{}

	// Identities.
	taken := map[string]bool{}
	for _, name := range sortedKeys(c.Identities) {
		id := c.Identities[name]
		e := resolvedEntry{Kind: kindIdentities, Name: name}
		acct, declared := byName[id.Account]
		switch {
		case !declared:
			e.How, e.Why = refused, fmt.Sprintf("its account %s is not in the setting accounts", id.Account)
		case acct.How == refused:
			e.How, e.Why = refused, fmt.Sprintf("its account %s is refused: betterbird_check says why", id.Account)
		case id.Address == "":
			e.How, e.Key = acct.How, acct.Keys.Identity
			if taken[e.Key] {
				e.How, e.Key, e.Why = refused, "", fmt.Sprintf("account %s has its default identity declared twice", id.Account)
			}
		default:
			list := listOfAccount[acct.Keys.Account]
			var others []string
			if len(list) > 1 {
				others = list[1:]
			}
			present := func(k string) bool {
				for _, x := range others {
					if x == k {
						return true
					}
				}
				return false
			}
			matches := func(k string) bool {
				return strings.EqualFold(unquote(prefs["mail.identity."+k+".useremail"]), id.Address)
			}
			e = resolveEntry(kindIdentities, name, id.Key, ownIdentityKey(name), rec.Entries[kindIdentities][name],
				others, present, matches, taken, "an identity of its account with its address",
				"give the one to adopt as key in this node's layer of the setting identities")
			if e.How == created {
				plan.identityLists[acct.Keys.Account] = append(plan.identityLists[acct.Keys.Account], e.Key)
			}
		}
		if e.How != refused {
			taken[e.Key] = true
			identityKeyOf[name] = e.Key
			plan.lines = append(plan.lines, fmt.Sprintf("// identity %s: %s under %s", name, e.How, e.Key))
			plan.lines = append(plan.lines, identityLines(e, id, acct)...)
		}
		plan.Entries = append(plan.Entries, e)
	}
	// A created account's identity list is the module's whole: its default and the identities it created.
	for _, name := range sortedKeys(byName) {
		r := byName[name]
		if r.How == created && len(plan.identityLists[r.Keys.Account]) > 0 {
			list := append([]string{r.Keys.Identity}, plan.identityLists[r.Keys.Account]...)
			plan.lines = append(plan.lines, fmt.Sprintf("user_pref(%s, %s);", quoted("mail.account."+r.Keys.Account+".identities"),
				quoted(strings.Join(list, ","))))
			delete(plan.identityLists, r.Keys.Account)
		}
	}
	// Adopted accounts keep their list in prefs.js: the module's own keys are written into it while Betterbird is
	// closed. An adopted account whose list holds none of them and wants none is left out.
	for _, a := range have {
		if _, wanted := plan.identityLists[a.Key]; wanted {
			continue
		}
		for _, k := range a.Identities {
			if ownIdentity.MatchString(k) {
				plan.identityLists[a.Key] = []string{}
				break
			}
		}
	}

	// Calendars.
	cals := profileCalendars(prefs)
	calKeys := map[string]profileCalendar{}
	var caldav []string
	for _, pc := range cals {
		calKeys[pc.Key] = pc
		if pc.Kind == "caldav" {
			caldav = append(caldav, pc.Key)
		}
	}
	taken = map[string]bool{}
	for _, name := range sortedKeys(c.Calendars) {
		cal := c.Calendars[name]
		present := func(k string) bool { pc, ok := calKeys[k]; return ok && pc.Kind == "caldav" }
		matches := func(k string) bool { return sameURL(calKeys[k].Value.URL, cal.URL) }
		e := resolveEntry(kindCalendars, name, cal.Key, ownCalendarKey(name), rec.Entries[kindCalendars][name],
			caldav, present, matches, taken, "a CalDAV calendar at its address",
			"remove the duplicate in Betterbird, or give the one to adopt as key in this node's layer of the setting calendars")
		if e.How != refused {
			taken[e.Key] = true
			if e.How == created {
				plan.calendarOrder = append(plan.calendarOrder, e.Key)
			}
			plan.lines = append(plan.lines, fmt.Sprintf("// calendar %s: %s under %s", name, e.How, e.Key))
			plan.lines = append(plan.lines, calendarLines(e, cal, identityKeyOf[cal.Invitations])...)
		}
		plan.Entries = append(plan.Entries, e)
	}

	// Address books.
	books := profileAddressBooks(prefs)
	bookKeys := map[string]profileAddressBook{}
	var carddav []string
	for _, b := range books {
		bookKeys[b.Key] = b
		if b.CardDAV {
			carddav = append(carddav, b.Key)
		}
	}
	taken = map[string]bool{}
	for _, name := range sortedKeys(c.AddressBooks) {
		ab := c.AddressBooks[name]
		present := func(k string) bool { b, ok := bookKeys[k]; return ok && b.CardDAV }
		matches := func(k string) bool { return sameURL(bookKeys[k].Value.URL, ab.URL) }
		e := resolveEntry(kindAddressBooks, name, ab.Key, ownBookKey(name), rec.Entries[kindAddressBooks][name],
			carddav, present, matches, taken, "a CardDAV address book at its address",
			"remove the duplicate in Betterbird, or give the one to adopt as key in this node's layer of the setting address-books")
		if e.How != refused {
			taken[e.Key] = true
			plan.lines = append(plan.lines, fmt.Sprintf("// address book %s: %s under %s", name, e.How, e.Key))
			plan.lines = append(plan.lines, addressBookLines(e, ab, name)...)
		}
		plan.Entries = append(plan.Entries, e)
	}

	// Tags: a tag's key is its own, unique in a profile, so a match is never ambiguous.
	tagKeys := map[string]bool{}
	for _, t := range profileTags(prefs) {
		tagKeys[t.Key] = true
	}
	for _, key := range sortedKeys(c.Tags) {
		t := c.Tags[key]
		e := resolvedEntry{Kind: kindTags, Name: key, Key: key, How: adopted}
		if was, ok := rec.Entries[kindTags][key]; ok && was.How == created {
			e.How = created
		} else if !tagKeys[key] {
			e.How = created
		}
		plan.lines = append(plan.lines, fmt.Sprintf("// tag %s: %s", key, e.How))
		plan.lines = append(plan.lines, tagLines(key, t)...)
		plan.Entries = append(plan.Entries, e)
	}

	// What the setting no longer holds: an adopted entry is released (its lines go), a created one's preferences
	// are removed from prefs.js while Betterbird is closed.
	declaredNow := map[string]map[string]bool{}
	for _, e := range plan.Entries {
		if declaredNow[e.Kind] == nil {
			declaredNow[e.Kind] = map[string]bool{}
		}
		declaredNow[e.Kind][e.Name] = true
		if e.How != refused {
			if plan.record.Entries[e.Kind] == nil {
				plan.record.Entries[e.Kind] = map[string]recordedEntry{}
			}
			plan.record.Entries[e.Kind][e.Name] = recordedEntry{How: e.How, Key: e.Key}
		}
	}
	for _, kind := range []string{kindIdentities, kindCalendars, kindAddressBooks, kindTags} {
		for _, name := range sortedKeys(rec.Entries[kind]) {
			was := rec.Entries[kind][name]
			if declaredNow[kind][name] || was.How != created {
				continue
			}
			switch kind {
			case kindIdentities:
				plan.removals = append(plan.removals, "mail.identity."+was.Key+".")
			case kindCalendars:
				plan.removals = append(plan.removals, "calendar.registry."+was.Key+".")
			case kindAddressBooks:
				plan.removals = append(plan.removals, "ldap_2.servers."+was.Key+".")
			case kindTags:
				plan.removals = append(plan.removals, "mailnews.tags."+was.Key+".")
			}
		}
	}

	// Filters, owned whole per declared account (§8).
	for _, account := range sortedAccountsOf(c.Filters) {
		fp := filterPlan{Account: account}
		r, ok := byName[account]
		switch {
		case !ok:
			fp.Refused = fmt.Sprintf("its account %s is not in the setting accounts", account)
		case r.How == refused:
			fp.Refused = fmt.Sprintf("its account %s is refused: betterbird_check says why", account)
		default:
			dir := m.accountDirectory(profile.path, prefs, r.Keys.Server)
			if dir == "" {
				fp.Waiting = "Betterbird has not made the account's directory yet: it does at its first start with the account"
				break
			}
			fp.path = filepath.Join(dir, filterFileName)
			fp.File = m.tilde(strings.TrimPrefix(fp.path, m.Root))
			fp.want = renderFilters(c.Filters[account], folderBase(prefs, r.Keys.Server))
			raw, err := readBounded(fp.path)
			fp.exists = err == nil
			fp.have = string(raw)
		}
		was := rec.Filters[account]
		was.Released = false
		if fp.path != "" {
			was.File = fp.File
		}
		if was.File != "" || was.Kept != "" {
			plan.record.Filters[account] = was
		}
		plan.filters = append(plan.filters, fp)
	}
	for _, account := range sortedKeys(rec.Filters) {
		if _, still := c.Filters[account]; still {
			continue
		}
		was := rec.Filters[account]
		if !was.Released {
			plan.released = append(plan.released, account)
		}
		was.Released = true
		plan.record.Filters[account] = was
	}
	return plan
}

// resolveEntry resolves an identity, a calendar or an address book as ADR 0317 resolves an account (§7).
func resolveEntry(kind, name, layerKey, own string, was recordedEntry, candidates []string, present, matches func(string) bool,
	taken map[string]bool, what, remedy string) resolvedEntry {
	e := resolvedEntry{Kind: kind, Name: name}
	refuse := func(format string, args ...any) resolvedEntry {
		e.How, e.Key, e.Why = refused, "", fmt.Sprintf(format, args...)
		return e
	}
	// 1. Recorded, while the profile still holds it.
	if was.Key != "" && !taken[was.Key] && (present(was.Key) || was.How == created) && (layerKey == "" || layerKey == was.Key) {
		e.How, e.Key = was.How, was.Key
		return e
	}
	// 2. Under the module's own key: its creation.
	if present(own) {
		e.How, e.Key = created, own
		return e
	}
	// 3. The key a node's layer names.
	if layerKey != "" {
		switch {
		case !present(layerKey):
			return refuse("the key %s this node's layer names is not in the profile", layerKey)
		case taken[layerKey]:
			return refuse("the key %s is already another declared entry's", layerKey)
		case !matches(layerKey):
			return refuse("the key %s this node's layer names is not %s", layerKey, what)
		}
		e.How, e.Key = adopted, layerKey
		return e
	}
	// 4. By the match.
	var found []string
	for _, k := range candidates {
		if !taken[k] && !ownMeshKey.MatchString(k) && !ownIdentity.MatchString(k) && matches(k) {
			found = append(found, k)
		}
	}
	switch len(found) {
	case 0:
		e.How, e.Key = created, own
	case 1:
		e.How, e.Key = adopted, found[0]
	default:
		return refuse("%d entries in the profile are %s (%s): %s (novox/hq ADR 0329 §7)", len(found), what,
			strings.Join(found, ", "), remedy)
	}
	return e
}

// sameURL compares two addresses without a trailing slash's difference.
func sameURL(a, b string) bool {
	return a != "" && strings.EqualFold(strings.TrimRight(a, "/"), strings.TrimRight(b, "/"))
}

func pref(name, value string) string { return fmt.Sprintf("user_pref(%s, %s);", quoted(name), value) }

func boolWord(b bool) string { return strconv.FormatBool(b) }

// identityLines are an identity's declared fields under its key. The default identity's name and address are
// the setting accounts' (§4), so only another identity carries them here.
func identityLines(e resolvedEntry, id *Identity, acct resolvedAccount) []string {
	p := "mail.identity." + e.Key + "."
	var out []string
	if id.Address != "" {
		out = append(out, pref(p+"fullName", jsQuoted(id.Name)), pref(p+"useremail", jsQuoted(id.Address)))
		if e.How == created {
			out = append(out, pref(p+"valid", "true"), pref(p+"smtpServer", quoted(acct.Keys.SMTP)))
		}
	}
	above := 0
	if id.SignatureAboveQuote {
		above = 1
	}
	out = append(out,
		pref(p+"reply_to", jsQuoted(id.ReplyTo)),
		pref(p+"organization", jsQuoted(id.Organization)),
		pref(p+"htmlSigText", jsQuoted(strings.Join(id.Signature, "\n"))),
		pref(p+"htmlSigFormat", boolWord(id.SignatureHTML)),
		pref(p+"attach_signature", "false"),
		pref(p+"reply_on_top", strconv.Itoa(above)),
		pref(p+"sig_bottom", boolWord(!id.SignatureAboveQuote)))
	return out
}

func calendarLines(e resolvedEntry, cal *Calendar, identityKey string) []string {
	p := "calendar.registry." + e.Key + "."
	var out []string
	if e.How == created {
		out = append(out, pref(p+"type", quoted("caldav")), pref(p+"cache.enabled", "true"),
			pref(p+"calendar-main-in-composite", "true"))
	}
	reminders := cal.Reminders == nil || *cal.Reminders
	out = append(out, pref(p+"uri", jsQuoted(cal.URL)), pref(p+"name", jsQuoted(cal.Name)))
	if cal.Color != "" {
		out = append(out, pref(p+"color", jsQuoted(strings.ToLower(cal.Color))))
	}
	out = append(out, pref(p+"readOnly", boolWord(cal.ReadOnly)), pref(p+"suppressAlarms", boolWord(!reminders)),
		pref(p+"username", jsQuoted(cal.User)), pref(p+"imip.identity.key", jsQuoted(identityKey)))
	return out
}

func addressBookLines(e resolvedEntry, ab *AddressBook, name string) []string {
	p := "ldap_2.servers." + e.Key + "."
	var out []string
	if e.How == created {
		out = append(out, pref(p+"dirType", "102"), pref(p+"filename", quoted("abook-mesh_"+name+".sqlite")))
	}
	return append(out, pref(p+"description", jsQuoted(ab.Name)), pref(p+"carddav.url", jsQuoted(ab.URL)),
		pref(p+"carddav.username", jsQuoted(ab.User)))
}

func tagLines(key string, t *Tag) []string {
	p := "mailnews.tags." + key + "."
	out := []string{pref(p+"tag", jsQuoted(t.Name))}
	if t.Color != "" {
		out = append(out, pref(p+"color", jsQuoted(strings.ToUpper(t.Color))))
	}
	if t.Order > 0 {
		out = append(out, pref(p+"ordinal", quoted(tagOrdinal(t.Order))))
	}
	return out
}

// configBlock is the user.js block of the five kinds.
func (p configPlan) configBlock() string {
	if len(p.lines) == 0 {
		return ""
	}
	return "\n// The identities, calendars, address books and tags the settings declare (novox/hq ADR 0329), under the\n" +
		"// keys each was adopted or created under. No password, token or cookie.\n" + strings.Join(p.lines, "\n") + "\n"
}

// closedFor says why the profile's own files may not be written now, or "": Betterbird runs, or the profile's
// lock says one holds it (§9).
func (m *Machine) closedFor(profile string) string {
	if ps := m.mainProcs(); len(ps) > 0 {
		return fmt.Sprintf("Betterbird is running (pid %d), and it rewrites these files when it quits", ps[0].PID)
	}
	if _, err := os.Lstat(filepath.Join(profile, "lock")); err == nil {
		return "the profile is locked (its lock file is there): a Betterbird holds it, or one ended without quitting"
	}
	return ""
}

// prefsChanges is prefs.js as the plan wants it, and how many changes each kind has in it.
func (p configPlan) prefsChanges(text string) (string, map[string]int) {
	counts := map[string]int{}
	var lines []string
	done := map[string]bool{}
	s := bufio.NewScanner(strings.NewReader(text))
	s.Buffer(make([]byte, 64<<10), 4<<20)
	for s.Scan() {
		line := s.Text()
		mm := prefLine.FindStringSubmatch(line)
		if mm == nil {
			lines = append(lines, line)
			continue
		}
		name := mm[1]
		removed := false
		for _, prefix := range p.removals {
			if strings.HasPrefix(name, prefix) {
				removed = true
				counts[kindOfPrefix(prefix)]++
				break
			}
		}
		if removed {
			continue
		}
		if acct, ok := strings.CutPrefix(name, "mail.account."); ok && strings.HasSuffix(acct, ".identities") {
			key := strings.TrimSuffix(acct, ".identities")
			if want, ok := p.identityLists[key]; ok {
				done[name] = true
				next := listedWithOwn(listOf(mm[2]), want, ownIdentity.MatchString, ",")
				if next != strings.Join(listOf(mm[2]), ",") {
					line = pref(name, quoted(next))
					counts[kindIdentities]++
				}
			}
		}
		if name == "calendar.list.sortOrder" {
			done[name] = true
			have := strings.Fields(unquote(mm[2]))
			next := listedWithOwn(have, p.calendarOrder, ownMeshKey.MatchString, " ")
			if next != strings.Join(have, " ") {
				line = pref(name, quoted(next))
				counts[kindCalendars]++
			}
		}
		lines = append(lines, line)
	}
	if !done["calendar.list.sortOrder"] && len(p.calendarOrder) > 0 {
		lines = append(lines, pref("calendar.list.sortOrder", quoted(strings.Join(p.calendarOrder, " "))))
		counts[kindCalendars]++
	}
	out := strings.Join(lines, "\n")
	if text == "" || strings.HasSuffix(text, "\n") {
		out += "\n"
	}
	return out, counts
}

func kindOfPrefix(prefix string) string {
	switch {
	case strings.HasPrefix(prefix, "mail.identity."):
		return kindIdentities
	case strings.HasPrefix(prefix, "calendar."):
		return kindCalendars
	case strings.HasPrefix(prefix, "ldap_2."):
		return kindAddressBooks
	}
	return kindTags
}

// listedWithOwn is a list with the module's own keys made the wanted ones, every other key in its place.
func listedWithOwn(have, wanted []string, own func(string) bool, sep string) string {
	want := map[string]bool{}
	for _, k := range wanted {
		want[k] = true
	}
	var out []string
	there := map[string]bool{}
	for _, k := range have {
		if own(k) && !want[k] {
			continue
		}
		out = append(out, k)
		there[k] = true
	}
	for _, k := range wanted {
		if !there[k] {
			out = append(out, k)
		}
	}
	return strings.Join(out, sep)
}

// Waiting counts, per kind, the changes of what Betterbird rewrites that wait for it to close (§9).
func (m *Machine) waiting(profile string, p configPlan, ra []resolvedAccount) map[string]int {
	raw, _ := readBounded(filepath.Join(profile, "prefs.js"))
	_, counts := p.prefsChanges(string(raw))
	var wantAccounts, wantSMTP []string
	for _, r := range ra {
		if r.How == created {
			wantAccounts, wantSMTP = append(wantAccounts, r.Keys.Account), append(wantSMTP, r.Keys.SMTP)
		}
	}
	if _, changed := withListed(string(raw), map[string][]string{
		"mail.accountmanager.accounts": wantAccounts, "mail.smtpservers": wantSMTP}); changed {
		counts["accounts"]++
	}
	for _, f := range p.filters {
		if f.changes() {
			counts[kindFilters]++
		}
	}
	for k, v := range counts {
		if v == 0 {
			delete(counts, k)
		}
	}
	return counts
}

// writeClosed writes what Betterbird rewrites itself, only while it is closed: prefs.js's lists and the
// removals, and each declared account's filter file, keeping the file it replaces at its first write. It
// answers what it wrote, or why it waits.
func (m *Machine) writeClosed(profile Profile, p *configPlan) (string, error) {
	var said []string
	path := filepath.Join(profile.path, "prefs.js")
	raw, err := readBounded(path)
	if err != nil && !errors.Is(err, os.ErrNotExist) {
		return "", err
	}
	next, counts := p.prefsChanges(string(raw))
	pending := next != string(raw)
	for _, f := range p.filters {
		pending = pending || f.changes()
	}
	if !pending {
		return "unchanged", nil
	}
	if why := m.closedFor(profile.path); why != "" {
		return "", errors.New(why + ": the identities' and calendars' lists, the removals and the filter files are " +
			"written at its next start from the launcher, or by betterbird_restart")
	}
	if next != string(raw) {
		mode := os.FileMode(0o600)
		if st, err := os.Stat(path); err == nil {
			mode = st.Mode().Perm()
		}
		if err := writeAtomic(path, []byte(next), mode); err != nil {
			return "", err
		}
		said = append(said, fmt.Sprintf("prefs.js: %d change(s) to the lists and removals", sum(counts)))
	}
	for i, f := range p.filters {
		if !f.changes() {
			continue
		}
		was := p.record.Filters[f.Account]
		if was.Kept == "" && f.exists {
			kept := m.keptFilterFile(profile.Dir, f.Account)
			if err := writeAtomic(kept, []byte(f.have), 0o600); err != nil {
				return strings.Join(said, "; "), fmt.Errorf("the filter file of %s was not written: the file it replaces could not be kept: %v", f.Account, err)
			}
			was.Kept = m.tilde(strings.TrimPrefix(kept, m.Root))
		}
		mode := os.FileMode(0o644)
		if st, err := os.Stat(f.path); err == nil {
			mode = st.Mode().Perm()
		}
		if err := writeAtomic(f.path, []byte(f.want), mode); err != nil {
			return strings.Join(said, "; "), err
		}
		was.File = f.File
		p.record.Filters[f.Account] = was
		p.filters[i].have, p.filters[i].exists = f.want, true
		said = append(said, "the filters of "+f.Account)
	}
	if len(said) == 0 {
		return "unchanged", nil
	}
	return "written: " + strings.Join(said, "; "), nil
}

func sum(m map[string]int) int {
	n := 0
	for _, v := range m {
		n += v
	}
	return n
}

// accountDirectory is an account's directory in the profile, as its server's preferences name it, or "" when
// they name none within the profile.
func (m *Machine) accountDirectory(profile string, prefs map[string]string, server string) string {
	if dir := accountDirectory(profile, prefs, server); dir != "" {
		return dir
	}
	abs := unquote(prefs["mail.server."+server+".directory"])
	if abs == "" {
		return ""
	}
	dir := m.path(abs)
	if strings.HasPrefix(filepath.Clean(dir), filepath.Clean(profile)+string(filepath.Separator)) {
		return dir
	}
	return ""
}

func mustJSON(v any) string {
	b, _ := json.Marshal(v)
	return string(bytes.TrimSpace(b))
}