// This file wires the package's render helpers (RenderReadings, Themes,
// themeCSS, the embedded static/templates FS) into an HTTP server: the full
// page (GET /), the HTMX reading-pane partial (GET /readings), a theme
// stylesheet endpoint (GET /theme.css) and the embedded static assets (GET
// /static/...).
package web

import (
	"fmt"
	"html/template"
	"io"
	"io/fs"
	"net"
	"net/http"
	"net/url"
	"os"
	"os/exec"
	"regexp"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/lukaszkasprzak/lectio/internal/bible"
	"github.com/lukaszkasprzak/lectio/internal/bookmarks"
	"github.com/lukaszkasprzak/lectio/internal/config"
	"github.com/lukaszkasprzak/lectio/internal/export"
	"github.com/lukaszkasprzak/lectio/internal/i18n"
	"github.com/lukaszkasprzak/lectio/internal/liturgy"
	"github.com/lukaszkasprzak/lectio/internal/readings"
	"github.com/lukaszkasprzak/lectio/internal/render"
)

// bibleVersions is the fixed, Themes-independent list of scripture versions
// the web UI's checkboxes offer -- independent of any one cfg.Versions, so
// every visitor sees the same five choices regardless of their config file.
var bibleVersions = []string{"wuj", "vul", "grb", "drb"}

// server holds the live, mutable config + book table so /settings can apply
// changes to the running process. All handlers read a snapshot via get()/table().
type server struct {
	mu  sync.RWMutex
	cfg config.Config
	tbl *bible.BookTable
	bm  *bookmarks.Store
}

func (s *server) get() config.Config      { s.mu.RLock(); defer s.mu.RUnlock(); return s.cfg }
func (s *server) table() *bible.BookTable { s.mu.RLock(); defer s.mu.RUnlock(); return s.tbl }
func (s *server) apply(cfg config.Config, tbl *bible.BookTable) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.cfg = cfg
	if tbl != nil {
		s.tbl = tbl
	}
}

// NewServer builds lectio-web's route tree. cfg supplies the defaults
// (lectionary, versions, theme, offline) that requests can override via
// query parameters; it is never mutated -- /settings applies changes to a
// live, mutable copy held by server, which every handler reads per request.
func NewServer(cfg config.Config) http.Handler {
	tbl, _ := bible.LoadBookTable(config.UserBooksINI())
	s := &server{cfg: cfg, tbl: tbl, bm: bookmarks.Open()}

	mux := http.NewServeMux()
	mux.HandleFunc("GET /{$}", func(w http.ResponseWriter, r *http.Request) { indexHandler(s.get())(w, r) })
	mux.HandleFunc("GET /readings", func(w http.ResponseWriter, r *http.Request) { readingsHandler(s.get())(w, r) })
	mux.HandleFunc("GET /export", func(w http.ResponseWriter, r *http.Request) { exportHandler(s.get())(w, r) })
	mux.HandleFunc("GET /calendar", func(w http.ResponseWriter, r *http.Request) { calendarHandler(s.get())(w, r) })
	mux.HandleFunc("GET /api/calendar.json", func(w http.ResponseWriter, r *http.Request) { apiCalendarJSONHandler(s.get())(w, r) })
	mux.HandleFunc("GET /calendar.ics", func(w http.ResponseWriter, r *http.Request) { calendarICSHandler(s.get())(w, r) })
	mux.HandleFunc("GET /reader", func(w http.ResponseWriter, r *http.Request) { readerHandler(s.get(), s.table())(w, r) })
	mux.HandleFunc("GET /theme.css", func(w http.ResponseWriter, r *http.Request) { themeCSSHandler(s.get())(w, r) })
	mux.HandleFunc("GET /source", sourceHandler)
	mux.HandleFunc("GET /settings", settingsGet(s))
	mux.HandleFunc("POST /settings", settingsPost(s))
	mux.HandleFunc("POST /reader/bookmark", addBookmark(s))
	mux.HandleFunc("GET /bookmarks", listBookmarks(s))
	mux.HandleFunc("POST /bookmarks/delete", deleteBookmark(s))

	staticSub, err := fs.Sub(staticFS, "static")
	if err != nil {
		// Unreachable: "static" is embedded at build time by render.go.
		panic(err)
	}
	mux.Handle("GET /static/", http.StripPrefix("/static/", http.FileServer(http.FS(staticSub))))

	return noStore(mux)
}

// noStore stops the browser caching any lectio-web response, so a rebuilt or
// reinstalled server never has an old page, base.css or theme.css served from
// cache (which presents as "switching themes stopped working" after an update).
func noStore(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Cache-Control", "no-store")
		h.ServeHTTP(w, r)
	})
}

// today is lectio-web's "no ?date=" default, in the YYYY-MM-DD form every
// other package's Date fields expect.
func today() string {
	return time.Now().Format("2006-01-02")
}

// dateRe validates a ?date= query param before it is ever handed to
// readings.Load/liturgy.Load, which build a filesystem cache path by string
// concatenation from it -- an unvalidated date is a path-traversal vector.
// Compiled once at package scope (not per request), the same shape as
// internal/cli's dateRe. See resolveQuery.
var dateRe = regexp.MustCompile(`^\d{4}-\d{2}-\d{2}$`)

// shiftDate adds days to date (YYYY-MM-DD); an unparsable date is returned
// unchanged, mirroring internal/tui's shiftDate.
func shiftDate(date string, days int) string {
	t, err := time.Parse("2006-01-02", date)
	if err != nil {
		return date
	}
	return t.AddDate(0, 0, days).Format("2006-01-02")
}

// requestVersions returns the versions requested via one or more repeated
// ?v= query params. The controls form always submits a hidden "vset" marker,
// so a request that carries "vset" but no "v" means the user unchecked EVERY
// version -- return none (the pane then shows nothing). A request with neither
// (a fresh visit or a bare link) falls back to cfg.WebVersions, else a single
// cfg.DefaultVersion, so a plain visit checks exactly one box.
func requestVersions(cfg config.Config, r *http.Request) []string {
	if vs, ok := r.URL.Query()["v"]; ok && len(vs) > 0 {
		return vs
	}
	if r.URL.Query().Has("vset") {
		return nil // form submitted with every box unchecked
	}
	if len(cfg.WebVersions) > 0 {
		return append([]string(nil), cfg.WebVersions...)
	}
	return []string{cfg.DefaultVersion}
}

// queryBool reads a truthy/falsy query param ("1"/"true"/"on"/"yes" vs.
// "0"/"false"/"off"/"no"), falling back to def when the param is absent or
// unrecognized.
func queryBool(r *http.Request, name string, def bool) bool {
	if !r.URL.Query().Has(name) {
		return def
	}
	switch strings.ToLower(r.URL.Query().Get(name)) {
	case "1", "true", "on", "yes":
		return true
	case "0", "false", "off", "no":
		return false
	default:
		return def
	}
}

// requestLectionary returns the ?lectionary= override, falling back to
// cfg.Lectionary.
func requestLectionary(cfg config.Config, r *http.Request) string {
	if l := r.URL.Query().Get("lectionary"); l != "" {
		return l
	}
	return cfg.Lectionary
}

// requestDisplay returns the ?display= override (normalized the same way
// config.Load normalizes cfg.WebDisplay, so a bad/unknown value falls back
// to "horizontal" rather than reaching RenderReadings unchecked), falling
// back to cfg.WebDisplay when the param is absent.
func requestDisplay(cfg config.Config, r *http.Request) string {
	if d := r.URL.Query().Get("display"); d != "" {
		return config.NormalizeDisplay(d)
	}
	return cfg.WebDisplay
}

// resolveQuery resolves the date/lectionary/all/versions/display controls
// shared by indexHandler and readingsHandler from cfg (the defaults) and
// r's query params (the overrides) -- one place for both handlers so they
// can't drift.
func resolveQuery(cfg config.Config, r *http.Request) (date, lectionary string, all bool, versions []string, display string) {
	date = r.URL.Query().Get("date")
	if date == "" || !dateRe.MatchString(date) {
		date = today()
	}
	lectionary = requestLectionary(cfg, r)
	all = queryBool(r, "all", cfg.All)
	versions = requestVersions(cfg, r)
	display = requestDisplay(cfg, r)
	return date, lectionary, all, versions, display
}

// loadSections computes one request's readings offline: date/lectionary
// override cfg, all controls part filtering, and versions is passed through
// render.EffectiveVersions (which maps any legacy "bt" to "wuj") so the
// caller's column labels always match what was actually loadable. dayInfo is
// the day's celebration identity (see liturgy.DayInfo), zero when none.
func loadSections(cfg config.Config, lectionary, date string, all bool, versions []string) (secs []liturgy.Section, dayInfo liturgy.DayInfo, effVersions []string, err error) {
	cfg.Lectionary = lectionary
	effVersions = render.EffectiveVersions(versions, lectionary, cfg.Offline)
	secs, dayInfo, err = readings.Load(cfg, readings.Options{Date: date, All: all})
	return secs, dayInfo, effVersions, err
}

// indexData is what templates/index.html ranges/branches over.
type indexData struct {
	Date, PrevDate, NextDate string
	Lectionary               string
	VersionOpts              []versionOpt
	All                      bool
	ThemeOpts                []themeOpt
	Theme                    string
	Display                  string
	Mono                     bool
	Reading                  template.HTML
	// L holds the localised control labels (lectionary/layout/theme/...),
	// set from i18n.Get(cfg.UILanguage) -- index.html references its
	// fields (e.g. {{.L.Lectionary}}) instead of hardcoded Polish text.
	L i18n.UI
	// Lang is cfg.UILanguage, rendered into <html lang="...">.
	Lang string
}

type versionOpt struct {
	Code    string
	Checked bool
}

type themeOpt struct {
	Name     string
	Selected bool
}

// indexHandler serves the full page: controls reflecting the request's
// query (defaulting from cfg) plus the reading pane pre-rendered for that
// same query, so a plain (JS-less) GET / already shows today's gospel.
func indexHandler(cfg config.Config) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		date, lectionary, all, versions, display := resolveQuery(cfg, r)
		theme := r.URL.Query().Get("theme")
		if theme == "" {
			theme = cfg.WebTheme
		}

		// No version selected -> fetch nothing and show nothing (empty pane, no
		// day-info/headings); loadVersions stays nil so no box is checked.
		var reading template.HTML
		var loadVersions []string
		if len(versions) > 0 {
			secs, dayInfo, lv, err := loadSections(cfg, lectionary, date, all, versions)
			loadVersions = lv
			reading = renderOrError(secs, lv, lectionary, display, cfg.UILanguage, dayInfo, err)
		}

		// Check the boxes for the versions actually rendered (loadVersions),
		// not the raw request: traditional/offline substitute pl->wuj, so the
		// pl box must not show checked while Wujek is what's displayed.
		selected := map[string]bool{}
		for _, v := range loadVersions {
			selected[v] = true
		}
		versionOpts := make([]versionOpt, 0, len(bibleVersions))
		for _, v := range bibleVersions {
			versionOpts = append(versionOpts, versionOpt{Code: v, Checked: selected[v]})
		}

		themes := Themes()
		themeOpts := make([]themeOpt, 0, len(themes))
		for _, name := range themes {
			themeOpts = append(themeOpts, themeOpt{Name: name, Selected: name == theme})
		}

		data := indexData{
			Date:        date,
			PrevDate:    shiftDate(date, -1),
			NextDate:    shiftDate(date, 1),
			Lectionary:  lectionary,
			VersionOpts: versionOpts,
			All:         all,
			ThemeOpts:   themeOpts,
			Theme:       theme,
			Display:     display,
			Mono:        queryBool(r, "mono", cfg.WebMono),
			Reading:     reading,
			L:           i18n.Get(cfg.UILanguage),
			Lang:        cfg.UILanguage,
		}

		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		if err := tmpl.ExecuteTemplate(w, "index.html", data); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
	}
}

// readingsHandler serves the HTMX reading-pane partial: a fragment only,
// produced entirely by RenderReadings (never re-implemented here).
func readingsHandler(cfg config.Config) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		date, lectionary, all, versions, display := resolveQuery(cfg, r)

		var reading template.HTML
		if len(versions) > 0 {
			secs, dayInfo, loadVersions, err := loadSections(cfg, lectionary, date, all, versions)
			reading = renderOrError(secs, loadVersions, lectionary, display, cfg.UILanguage, dayInfo, err)
		}

		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		io.WriteString(w, string(reading))
	}
}

// exportHandler serves GET /export?fmt=txt|md|pdf: the current day's readings
// as a downloadable file (Content-Disposition attachment), reusing the same
// date/lectionary/all/version resolution as the reading pane.
func exportHandler(cfg config.Config) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if l := r.URL.Query().Get("lang"); l != "" {
			cfg.UILanguage = config.NormalizeUILanguage(l)
		}
		date, lectionary, all, versions, _ := resolveQuery(cfg, r)
		secs, dayInfo, loadVersions, err := loadSections(cfg, lectionary, date, all, versions)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		if len(secs) == 0 {
			http.Error(w, i18n.Get(cfg.UILanguage).NoReadingsDay, http.StatusNotFound)
			return
		}
		version := cfg.DefaultVersion
		if len(loadVersions) > 0 {
			version = loadVersions[0]
		}

		switch r.URL.Query().Get("fmt") {
		case "pdf":
			data, perr := export.ReadingsPDF(date, dayInfo, secs, version, lectionary, cfg.UILanguage)
			if perr != nil {
				http.Error(w, perr.Error(), http.StatusInternalServerError)
				return
			}
			w.Header().Set("Content-Type", "application/pdf")
			w.Header().Set("Content-Disposition", `attachment; filename="lectio-`+date+`.pdf"`)
			w.Write(data)
		case "md":
			w.Header().Set("Content-Type", "text/markdown; charset=utf-8")
			w.Header().Set("Content-Disposition", `attachment; filename="lectio-`+date+`.md"`)
			io.WriteString(w, export.Markdown(date, dayInfo, secs, version, lectionary, cfg.UILanguage))
		default:
			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
			w.Header().Set("Content-Disposition", `attachment; filename="lectio-`+date+`.txt"`)
			io.WriteString(w, export.Text(date, dayInfo, secs, version, lectionary, cfg.UILanguage))
		}
	}
}

// calendarHandler serves GET /calendar?month=YYYY-MM&lectionary=: a printable
// A4 PDF month calendar of the celebration names + gospel references. Missing/
// bad month defaults to the current month.
func calendarHandler(cfg config.Config) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if l := r.URL.Query().Get("lang"); l != "" {
			cfg.UILanguage = config.NormalizeUILanguage(l)
		}
		t, err := time.Parse("2006-01", r.URL.Query().Get("month"))
		if err != nil {
			t = time.Now()
		}
		year, month := t.Year(), int(t.Month())
		cfg.Lectionary = requestLectionary(cfg, r)
		first := time.Date(year, time.Month(month), 1, 0, 0, 0, 0, time.UTC)

		var days []export.CalendarDay
		for d := first; int(d.Month()) == month; d = d.AddDate(0, 0, 1) {
			cd := export.CalendarDay{Day: d.Day()}
			if secs, info, lerr := readings.Load(cfg, readings.Options{Date: d.Format("2006-01-02"), All: false}); lerr == nil {
				cd.Name = info.Name
				cd.Colour = info.Colour
				cd.Citation = readings.GospelCitation(secs)
			}
			days = append(days, cd)
		}

		data, perr := export.CalendarPDF(year, month, days, cfg.Lectionary, cfg.UILanguage)
		if perr != nil {
			http.Error(w, perr.Error(), http.StatusInternalServerError)
			return
		}
		w.Header().Set("Content-Type", "application/pdf")
		w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="lectio-%04d-%02d-calendar.pdf"`, year, month))
		w.Write(data)
	}
}

// renderOrError returns RenderReadings' fragment, or (on a readings.Load
// error, or no sections at all for the date) a small escaped error
// paragraph, localised via lang -- readings.Load errors are expected in
// normal operation (an unpublished date, no network while online, ...) so
// the pane should show them, not 500.
func renderOrError(secs []liturgy.Section, versions []string, lectionary, display, lang string, dayInfo liturgy.DayInfo, err error) template.HTML {
	if err != nil {
		return template.HTML(`<p class="error">` + template.HTMLEscapeString(err.Error()) + `</p>`)
	}
	if len(secs) == 0 {
		return template.HTML(`<p class="error">` + template.HTMLEscapeString(i18n.Get(lang).NoReadingsDay) + `</p>`)
	}
	return RenderReadings(secs, versions, lectionary, display, lang, dayInfo)
}

// requestReaderVersions returns the corpus versions the reader request asks for
// (repeated ?v=), dropping "bt" (no corpus) and anything invalid; falling back
// to the configured default (or "wuj" when that is bt/invalid) so a plain visit
// shows exactly one column.
func requestReaderVersions(cfg config.Config, r *http.Request) []string {
	var out []string
	for _, v := range r.URL.Query()["v"] {
		if v != "bt" && config.ValidVersion(v) {
			out = append(out, v)
		}
	}
	if len(out) == 0 {
		d := cfg.DefaultVersion
		if d == "bt" || !config.ValidVersion(d) {
			d = "wuj"
		}
		out = []string{d}
	}
	return out
}

// findBook returns the BookInfo whose Canonical matches, and whether found.
func findBook(books []bible.BookInfo, canonical string) (bible.BookInfo, bool) {
	for _, b := range books {
		if b.Canonical == canonical {
			return b, true
		}
	}
	return bible.BookInfo{}, false
}

// clampChap keeps chap within the book's available chapters (contiguous in
// practice); 0 when the book has none in any corpus version.
func clampChap(chap int, chaps []int) int {
	if len(chaps) == 0 {
		return 0
	}
	if chap < chaps[0] {
		return chaps[0]
	}
	last := chaps[len(chaps)-1]
	if chap > last {
		return last
	}
	return chap
}

// atoiDefault parses s as an int, returning def when it is empty/unparsable.
func atoiDefault(s string, def int) int {
	if n, err := strconv.Atoi(strings.TrimSpace(s)); err == nil {
		return n
	}
	return def
}

type readerData struct {
	BookOpts           []bookOpt
	Book               string // canonical name of the selected book (for the bookmark-add form)
	Chap               int
	PrevChap, NextChap int
	ChapOpts           []chapOpt
	VersionOpts        []versionOpt
	Display            string
	ThemeOpts          []themeOpt
	Theme              string
	Mono               bool
	Reading            template.HTML
	L                  i18n.UI
	Lang               string
}

type bookOpt struct {
	Value    string // canonical name (corpus/query value)
	Label    string // dialect display name
	Selected bool
}

type chapOpt struct {
	N        int
	Selected bool
}

// readerHandler serves GET /reader: a book picker (dialect names), chapter
// navigation and corpus-version compare, rendering the same reading-pane
// templates/themes as the daily view. The controls form re-fetches /reader and
// hx-selects #reader-root, so book/chapter/version selects stay in sync.
func readerHandler(cfg config.Config, tbl *bible.BookTable) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		books := tbl.Books(cfg.SiglaLang())
		if len(books) == 0 { // defensive: embedded table always has books
			http.Error(w, "web: no books", http.StatusInternalServerError)
			return
		}

		info, ok := findBook(books, r.URL.Query().Get("book"))
		if !ok {
			info = books[0]
		}
		versions := requestReaderVersions(cfg, r)
		chaps := UnionChapters(info.Canonical)
		first := 1
		if len(chaps) > 0 {
			first = chaps[0]
		}
		chap := clampChap(atoiDefault(r.URL.Query().Get("chap"), first), chaps)
		display := requestDisplay(cfg, r)
		theme := r.URL.Query().Get("theme")
		if theme == "" {
			theme = cfg.WebTheme
		}

		reading := RenderPassage(info.Canonical, info.Name, chap, versions, display, cfg.UILanguage)

		bookOpts := make([]bookOpt, 0, len(books))
		for _, b := range books {
			bookOpts = append(bookOpts, bookOpt{Value: b.Canonical, Label: b.Name, Selected: b.Canonical == info.Canonical})
		}
		chapOpts := make([]chapOpt, 0, len(chaps))
		for _, c := range chaps {
			chapOpts = append(chapOpts, chapOpt{N: c, Selected: c == chap})
		}
		selected := map[string]bool{}
		for _, v := range versions {
			selected[v] = true
		}
		versionOpts := make([]versionOpt, 0, len(readerCorpusVersions))
		for _, v := range readerCorpusVersions {
			versionOpts = append(versionOpts, versionOpt{Code: v, Checked: selected[v]})
		}
		themes := Themes()
		themeOpts := make([]themeOpt, 0, len(themes))
		for _, name := range themes {
			themeOpts = append(themeOpts, themeOpt{Name: name, Selected: name == theme})
		}

		prev, next := chap-1, chap+1
		if len(chaps) > 0 {
			prev = clampChap(chap-1, chaps)
			next = clampChap(chap+1, chaps)
		}

		data := readerData{
			BookOpts:    bookOpts,
			Book:        info.Canonical,
			Chap:        chap,
			PrevChap:    prev,
			NextChap:    next,
			ChapOpts:    chapOpts,
			VersionOpts: versionOpts,
			Display:     display,
			ThemeOpts:   themeOpts,
			Theme:       theme,
			Mono:        queryBool(r, "mono", cfg.WebMono),
			Reading:     reading,
			L:           i18n.Get(cfg.UILanguage),
			Lang:        cfg.UILanguage,
		}

		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		if err := tmpl.ExecuteTemplate(w, "reader.html", data); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
	}
}

// addBookmark saves the current reader book+chapter with a note and tags, then
// returns to the reader at that location.
func addBookmark(s *server) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if err := r.ParseForm(); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}
		book := r.PostForm.Get("book")
		chap := atoiOr(r.PostForm.Get("chap"), 0)
		verse := atoiOr(r.PostForm.Get("verse"), 0)
		if verse < 0 {
			verse = 0
		}
		if book != "" && chap > 0 {
			_, _ = s.bm.Add(bookmarks.Bookmark{
				Book:    book,
				Chapter: chap,
				Verse:   verse,
				Note:    strings.TrimSpace(r.PostForm.Get("note")),
				Tags:    bookmarks.ParseTags(r.PostForm.Get("tags")),
			})
		}
		http.Redirect(w, r, "/reader?book="+url.QueryEscape(book)+"&chap="+strconv.Itoa(chap), http.StatusSeeOther)
	}
}

// bookmarkView is one row of templates/bookmarks.html.
type bookmarkView struct {
	ID      string
	Book    string // canonical (for the ?book= open link)
	Display string // dialect display name
	Chapter int
	Verse   int // 0 = whole chapter
	Note    string
	Tags    []string
	Created string
}

type bookmarksData struct {
	Items   []bookmarkView
	AllTags []string
	Tag     string // active filter ("" = all)
	L       i18n.UI
	Lang    string
}

// listBookmarks renders the bookmarks page, optionally filtered by ?tag=.
func listBookmarks(s *server) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		cfg := s.get()
		tag := r.URL.Query().Get("tag")
		items, err := s.bm.List(tag)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		names := map[string]string{}
		for _, b := range s.table().Books(cfg.SiglaLang()) {
			names[b.Canonical] = b.Name
		}
		views := make([]bookmarkView, 0, len(items))
		for _, b := range items {
			disp := names[b.Book]
			if disp == "" {
				disp = b.Book
			}
			views = append(views, bookmarkView{ID: b.ID, Book: b.Book, Display: disp, Chapter: b.Chapter, Verse: b.Verse, Note: b.Note, Tags: b.Tags, Created: b.Created})
		}
		allTags, _ := s.bm.Tags()
		data := bookmarksData{Items: views, AllTags: allTags, Tag: tag, L: i18n.Get(cfg.UILanguage), Lang: cfg.UILanguage}
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		if err := tmpl.ExecuteTemplate(w, "bookmarks.html", data); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
	}
}

// deleteBookmark removes a bookmark and returns to the list.
func deleteBookmark(s *server) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if err := r.ParseForm(); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}
		_ = s.bm.Delete(r.PostForm.Get("id"))
		http.Redirect(w, r, "/bookmarks", http.StatusSeeOther)
	}
}

// themeCSSHandler serves one theme's stylesheet: the requested name, or
// (unknown/invalid) cfg.WebTheme, or (that also unknown) the built-in
// default -- so an unrecognized ?name= degrades to a working theme instead
// of a broken page.
func themeCSSHandler(cfg config.Config) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		name := r.URL.Query().Get("name")
		css, err := themeCSS(name)
		if err != nil {
			css, err = themeCSS(cfg.WebTheme)
		}
		if err != nil {
			css, err = themeCSS(config.Default().WebTheme)
		}
		if err != nil {
			http.Error(w, "web: no theme available", http.StatusInternalServerError)
			return
		}
		w.Header().Set("Content-Type", "text/css; charset=utf-8")
		w.Write(css)
	}
}

// sourceHandler serves the AGPL-3.0 §13 source offer: where to obtain the
// code this server is running. Every page footer links here, so a user
// interacting with lectio-web over a network is never more than one click
// from the corresponding source.
//
// Deliberately dependency-free (no template, no config read): it must answer
// even when config is broken or a template failed to parse, because a §13
// offer that only works on healthy days is not an offer. Plain text keeps it
// readable by both a browser and curl.
func sourceHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	w.Header().Set("X-Content-Type-Options", "nosniff")
	fmt.Fprintf(w, `lectio %s
Licence: %s (GNU Affero General Public License, version 3 or later)
Source:  %s

lectio is free software. You may use, study, share and modify it under the
terms of the AGPL. The full licence text ships with the source as LICENSE.

Because this is the Affero GPL, section 13 applies to this server: if the
code running here has been MODIFIED, whoever operates it must offer you the
modified source. If this address does not lead to the version you are
talking to, that is the operator's obligation to fix, not lectio's.
`, config.Version, config.License, config.SourceURL)
}

// settingsData drives templates/settings.html.
type settingsData struct {
	Cfg            config.Config
	Books          string       // current books.ini text (user override, else the embedded default)
	ThemeOpts      []themeOpt   // for the web_theme <select>
	VersionOpts    []versionOpt // all five, Checked if in Cfg.Versions
	WebVersionOpts []versionOpt // all five, Checked if in Cfg.WebVersions
	Saved          bool         // show a "saved" note (post-redirect)
	Error          string       // validation error to show (empty = none)
	L              i18n.UI
	Lang           string
}

func newSettingsData(cfg config.Config, books, errMsg string, saved bool) settingsData {
	themes := Themes()
	opts := make([]themeOpt, 0, len(themes))
	for _, name := range themes {
		opts = append(opts, themeOpt{Name: name, Selected: name == cfg.WebTheme})
	}

	versionsSet := map[string]bool{}
	for _, v := range cfg.Versions {
		versionsSet[v] = true
	}
	versionOpts := make([]versionOpt, 0, len(bibleVersions))
	for _, v := range bibleVersions {
		versionOpts = append(versionOpts, versionOpt{Code: v, Checked: versionsSet[v]})
	}

	webVersionsSet := map[string]bool{}
	for _, v := range cfg.WebVersions {
		webVersionsSet[v] = true
	}
	webVersionOpts := make([]versionOpt, 0, len(bibleVersions))
	for _, v := range bibleVersions {
		webVersionOpts = append(webVersionOpts, versionOpt{Code: v, Checked: webVersionsSet[v]})
	}

	return settingsData{
		Cfg:            cfg,
		Books:          books,
		ThemeOpts:      opts,
		VersionOpts:    versionOpts,
		WebVersionOpts: webVersionOpts,
		Saved:          saved,
		Error:          errMsg,
		L:              i18n.Get(cfg.UILanguage),
		Lang:           cfg.UILanguage,
	}
}

func currentBooksText() string {
	if b := config.UserBooksINI(); len(b) > 0 {
		return string(b)
	}
	return string(bible.DefaultBooksINI())
}

// settingsGet renders the settings form for the live config.
func settingsGet(s *server) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		data := newSettingsData(s.get(), currentBooksText(), "", r.URL.Query().Get("saved") == "1")
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		if err := tmpl.ExecuteTemplate(w, "settings.html", data); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
	}
}

// settingsPost validates and persists the submitted settings + books.ini, then
// applies them to the running server and redirects (PRG). On a validation error
// it re-renders the form with the message and the user's edits, HTTP 200.
func settingsPost(s *server) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if err := r.ParseForm(); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		cfg := s.get() // start from live cfg so Parts/SchemaVersion are preserved
		cfg.Lectionary = normLect(r.PostForm.Get("lectionary"), cfg.Lectionary)
		cfg.UILanguage = config.NormalizeUILanguage(r.PostForm.Get("ui_language"))
		cfg.SiglaStyle = config.NormalizeSiglaStyle(r.PostForm.Get("sigla_style"))
		cfg.WebDisplay = config.NormalizeDisplay(r.PostForm.Get("web_display"))
		cfg.WebTheme = r.PostForm.Get("web_theme")
		cfg.DefaultVersion = r.PostForm.Get("default_version")
		cfg.Versions = r.PostForm["versions"]
		cfg.WebVersions = r.PostForm["web_versions"]
		cfg.All = r.PostForm.Get("all") != ""
		cfg.Offline = r.PostForm.Get("offline") != ""
		cfg.WebMono = r.PostForm.Get("web_mono") != ""
		cfg.Width = atoiOr(r.PostForm.Get("width"), cfg.Width)
		cfg.WebPort = atoiOr(r.PostForm.Get("web_port"), cfg.WebPort)
		cfg.Pager = r.PostForm.Get("pager")

		booksText := r.PostForm.Get("books")

		// Validate config.
		if err := config.Validate(cfg); err != nil {
			renderSettingsError(w, cfg, booksText, err.Error())
			return
		}
		// Validate books.ini (parse via the same loader the app uses).
		var newTbl *bible.BookTable
		if strings.TrimSpace(booksText) != "" {
			t, berr := bible.LoadBookTable([]byte(booksText))
			if berr != nil {
				renderSettingsError(w, cfg, booksText, "books.ini: "+berr.Error())
				return
			}
			newTbl = t
		}

		// Persist.
		if err := config.Save(cfg); err != nil {
			renderSettingsError(w, cfg, booksText, "saving config: "+err.Error())
			return
		}
		// Only write books.ini when the editor actually carried content, so a
		// submit with an empty/absent books field never clobbers an existing
		// override (the form always pre-fills the textarea).
		if strings.TrimSpace(booksText) != "" {
			if p, err := config.BooksPath(); err == nil {
				_ = os.WriteFile(p, []byte(booksText), 0o644)
			}
		}

		s.apply(cfg, newTbl)
		http.Redirect(w, r, "/settings?saved=1", http.StatusSeeOther)
	}
}

func renderSettingsError(w http.ResponseWriter, cfg config.Config, books, msg string) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.WriteHeader(http.StatusOK)
	_ = tmpl.ExecuteTemplate(w, "settings.html", newSettingsData(cfg, books, msg, false))
}

// normLect normalizes a lectionary form value, falling back to def on anything invalid.
func normLect(v, def string) string {
	if n, ok := config.NormalizeLectionary(v); ok {
		return n
	}
	return def
}

func atoiOr(s string, def int) int {
	if n, err := strconv.Atoi(strings.TrimSpace(s)); err == nil {
		return n
	}
	return def
}

// defaultWebPort is the port chooseListener prefers when cfg.WebPort is 0.
const defaultWebPort = 1099

// chooseListener binds the port to serve on, on loopback only (127.0.0.1) --
// lectio-web is documented as a personal tool and Run prints an
// http://localhost/... URL, so it must not be reachable from the LAN. port==0
// means "prefer defaultWebPort (1099), else let the OS pick a free port"; a
// non-zero port is bound exactly (and its bind error surfaced if the port is
// in use).
func chooseListener(port int) (net.Listener, error) {
	if port != 0 {
		return net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", port))
	}
	if ln, err := net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", defaultWebPort)); err == nil {
		return ln, nil
	}
	return net.Listen("tcp", "127.0.0.1:0") // 1099 taken -> any free port
}

// Run starts lectio-web: listens on cfg.WebPort via chooseListener (0
// prefers 1099, falling back to a free OS port), prints the URL, best-effort
// opens it in a browser, and serves until the listener errors.
func Run(cfg config.Config) error {
	ln, err := chooseListener(cfg.WebPort)
	if err != nil {
		return err
	}
	port := ln.Addr().(*net.TCPAddr).Port
	url := fmt.Sprintf("http://localhost:%d", port)
	fmt.Println("lectio-web on " + url)

	openBrowser(url) // best-effort; ignore failure (no browser, headless, ...)

	return http.Serve(ln, NewServer(cfg))
}

// openBrowser best-effort launches the platform's "open a URL" command;
// any failure (missing command, no display, ...) is silently ignored, as
// lectio-web is fully usable by just visiting the printed URL manually.
func openBrowser(url string) {
	var cmd *exec.Cmd
	switch runtime.GOOS {
	case "darwin":
		cmd = exec.Command("open", url)
	case "windows":
		cmd = exec.Command("cmd", "/c", "start", "", url)
	default:
		cmd = exec.Command("xdg-open", url)
	}
	_ = cmd.Start()
}