package web

import (
	"net/http"
	"strings"

	"gitea.dooplex.hu/admin/felhom-controller/internal/stacks"
)

// THE APP PAGE (v0.315.0) — one page per app, four tabs, each tab its own URL.
//
// Until v0.314.0 one app was spread over six pages: the details page, the install/settings page, the
// logs page, the export page, the per-app backup panel, and a details card for moving data. Every
// „Vissza" on them went to the app LIST, so there was no way back to the app, and Start/Restart/Stop
// sat in a page header looking like menu buttons.
//
//	/apps/{slug}            the default tab — settings when installed, the guide when not
//	/apps/{slug}/settings   „Beallitasok"     — Mukodes, the cards that need the household, the form
//	/apps/{slug}/data       „Adatok es mentes" — data folders, move, backup settings, export
//	/apps/{slug}/guide      „Utmutato"         — description, screenshots, first steps, guide, FAQ
//	/apps/{slug}/logs       „Naplo"            — the log, polled only here
//	/apps/{slug}/install    the install wizard (a page, not a tab)
//
// WHY SERVER-RENDERED TABS AND NOT PANELS. Links in alerts and e-mails have to land ON a tab, and the
// log poller must not run on the other three. One page with hidden panels gives neither.
//
// THE DEFAULT TAB IS RENDERED, NOT REDIRECTED. `/apps/{slug}` serves the settings tab's content with
// the URL unchanged, so the address an alert, a bookmark or the app list carries stays the app's one
// address.
//
// THE OLD URLS STILL WORK, AND ONLY FOR READS. Every `/stacks/{name}/…` GET answers 302 to its tab —
// never 301, which browsers cache beyond anyone's reach. Every POST on those paths is untouched: the
// backup form, the app-email toggle and the reveal endpoints keep their URLs and their handlers.

const (
	appTabSettings = "settings"
	appTabData     = "data"
	appTabGuide    = "guide"
	appTabLogs     = "logs"
	appTabInstall  = "install"
)

// appTabOrder is the tab bar, left to right. The guide is last of the three „about" tabs and the log
// after it, because the household opens the log least often and the order must not move under them.
var appTabOrder = []string{appTabSettings, appTabData, appTabGuide, appTabLogs}

// appPageHandler serves `/apps/{slug}` and `/apps/{slug}/{tab}`.
//
// A NOT-INSTALLED app has one view and one URL: every tab suffix answers 302 to the base, because a
// settings tab for an app with no settings and a log tab for a container that does not exist are
// four ways to reach the same empty page.
func (s *Server) appPageHandler(w http.ResponseWriter, r *http.Request, slug, tab string) {
	found, data, ok := s.appCommonData(w, r, slug)
	if !ok {
		return
	}

	// v0.320.0: a protected infra stack is installed by definition — it is part of the box (appCommonData sets
	// Infra). It gets the settings, guide and log tabs; never the data tab (its export, move and backup are not the
	// household's), and never the install wizard. Pinned by TestAppPage_InfraAppHasNoInstall.
	infra, _ := data["Infra"].(bool)
	installed := found.Deployed || infra
	if !installed {
		if tab != "" {
			http.Redirect(w, r, s.cfg.AppPageURL(slug), http.StatusFound)
			return
		}
		tab = appTabGuide
	}
	if infra && tab == appTabData {
		http.Redirect(w, r, s.cfg.AppPageURL(slug), http.StatusFound)
		return
	}
	if tab == "" {
		tab = appTabSettings
	}

	data["ActiveTab"] = tab
	tabs := s.appTabLinks(r, slug, installed, tab)
	if infra {
		kept := tabs[:0]
		for _, t := range tabs {
			if t.Key != appTabData {
				kept = append(kept, t)
			}
		}
		tabs = kept
	}
	data["AppTabs"] = tabs
	data["Deployed"] = installed
	// The shell's „Megnyitas" shows only for an app that is actually up — a link to a stopped app's
	// address lands on the catch-all page, which is a worse answer than no link.
	data["AppOperational"] = installed && isOperationalState(found.State)

	switch tab {
	case appTabSettings:
		s.renderAppSettingsTab(w, r, found, data)
	case appTabData:
		s.renderAppDataTab(w, r, found, data)
	case appTabGuide:
		s.renderAppGuideTab(w, r, found, data)
	case appTabLogs:
		s.renderAppLogsTab(w, r, found, data)
	default:
		http.NotFound(w, r)
	}
}

// AppTabLink is one entry of the tab bar.
type AppTabLink struct {
	Key    string // the ASCII tab id, also the `data-tab` attribute a test asserts on
	Href   string
	Label  string // filled per request, in the household's language
	Active bool
}

// appTabLinks builds the tab bar. Empty for a not-installed app: it has one view, so a bar of one
// tab would be furniture.
//
// The LABEL is taken here and not in the template, with a literal key per tab, because a template
// that composed its key (`T (printf "app_page.tab_%s" .Key)`) would be invisible to the
// marker-coverage gate — the key would exist in no greppable form and a missing translation would
// render the key itself to the household.
func (s *Server) appTabLinks(r *http.Request, slug string, deployed bool, active string) []AppTabLink {
	return s.appTabLinksLang(s.langFor(r), slug, deployed, active)
}

// appTabLinksLang is appTabLinks for a language that is already known — the i18n parity harness
// renders one case in both languages from one request, so it cannot go through langFor.
func (s *Server) appTabLinksLang(lang, slug string, deployed bool, active string) []AppTabLink {
	if !deployed {
		return nil
	}
	labels := map[string]string{
		appTabSettings: s.msgLang(lang, "app_page.tab_settings"),
		appTabData:     s.msgLang(lang, "app_page.tab_data"),
		appTabGuide:    s.msgLang(lang, "app_page.tab_guide"),
		appTabLogs:     s.msgLang(lang, "app_page.tab_logs"),
	}
	base := s.cfg.AppPageURL(slug)
	out := make([]AppTabLink, 0, len(appTabOrder))
	for _, key := range appTabOrder {
		out = append(out, AppTabLink{Key: key, Href: base + "/" + key, Label: labels[key], Active: key == active})
	}
	return out
}

// renderAppSettingsTab — „Mukodes" first (the three buttons that used to sit in the page header),
// then the cards that still want something from the household, then the install-time and optional
// settings the install page used to show in its deployed mode.
func (s *Server) renderAppSettingsTab(w http.ResponseWriter, r *http.Request, found *stacks.Stack, data map[string]interface{}) {
	// The form half of this tab is deployPageData's — the same keys the install page gets, with
	// AlreadyDeployed true. Merged OVER the common data, except the four keys that say which page
	// this is: those belong to the tab, not to the form.
	//
	// v0.320.0: an infra stack has no install form, no app.yaml and no catalog fields — its tab is „Mukodes"
	// (restart only) and, for FileBrowser, the login. deployPageData is not asked.
	if infra, _ := data["Infra"].(bool); !infra {
		if form, ok := s.deployPageData(w, r, found.Name); ok {
			mergeAppPageData(data, form)
		} else {
			return
		}
		data["AfterStartFields"] = s.afterStartFields(found)
	}
	data["LoginAnswer"] = loginAnswerFor(data, &found.Meta)
	data["Title"] = found.Meta.DisplayName
	data["TitleKey"], data["TitleArgs"] = "page.title.app_settings", []interface{}{found.Meta.DisplayName}
	s.executeTemplate(w, r, "app_settings", data)
}

// renderAppDataTab — where the files are, how to move them, how they are backed up, how to take them
// out. The three used to be a card on the details page, a panel reached from the backup page, and a
// page of its own.
func (s *Server) renderAppDataTab(w http.ResponseWriter, r *http.Request, found *stacks.Stack, data map[string]interface{}) {
	data["StackName"] = found.Name
	data["DisplayName"] = found.Meta.DisplayName
	if s.backupMgr != nil {
		info := s.backupMgr.Tier2Info(found.Name)
		data["Tier2"] = info
		if !info.IsHDDApp {
			// R-499: say where THIS box's whole-system backup goes, not where one usually does.
			data["SystemBackup"] = systemBackupFact(s.resolveBackupTargetState(r.Context()))
		}
	}
	if s.appExporter != nil {
		data["ExportOffered"] = true
		data["Drives"] = s.storageDriveList()
	}
	if flash := s.flashFrom(r, "flash"); flash != "" {
		data["Flash"] = flash
	}
	if flashErr := s.flashFrom(r, "flash_error"); flashErr != "" {
		data["FlashError"] = flashErr
	}
	data["Title"] = found.Meta.DisplayName
	data["TitleKey"], data["TitleArgs"] = "page.title.app_data", []interface{}{found.Meta.DisplayName}
	s.executeTemplate(w, r, "app_data", data)
}

// renderAppGuideTab — the app's own copy: what it is for, what it looks like, the first steps, the
// guide, the FAQ and the docs link. For a not-installed app this is the whole page, with „Telepites".
func (s *Server) renderAppGuideTab(w http.ResponseWriter, r *http.Request, found *stacks.Stack, data map[string]interface{}) {
	// A translation longer than the Hungarian guide is dropped silently by the overlay — say so once
	// here, where there is a logger and a request language.
	if secs, faq := found.Meta.GuideOverlayExtras(s.langFor(r)); secs > 0 || faq > 0 {
		s.logger.Printf("[WARN] [web] guide overlay for app %q in %q carries %d section(s) and %d FAQ entr(y/ies) beyond the Hungarian count — the extras are not rendered", found.Meta.Slug, s.langFor(r), secs, faq)
	}
	data["Title"] = found.Meta.DisplayName
	data["TitleKey"], data["TitleArgs"] = "page.title.app_guide", []interface{}{found.Meta.DisplayName}
	s.executeTemplate(w, r, "app_guide", data)
}

// renderAppLogsTab — today's logs page inside the shell. `?raw=1` still answers plain text, because
// that is what the tab's own poller asks for (and what the old /stacks/{name}/logs?raw=1 asked for,
// whose redirect carries the query through).
func (s *Server) renderAppLogsTab(w http.ResponseWriter, r *http.Request, found *stacks.Stack, data map[string]interface{}) {
	logs, err := s.stackMgr.GetLogs(found.Name, 200)
	if err != nil {
		logs = s.msg(r, "logs.fetch_failed", err)
	}
	if r.URL.Query().Get("raw") == "1" {
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		_, _ = w.Write([]byte(logs))
		return
	}
	data["Logs"] = logs
	data["Title"] = found.Meta.DisplayName
	data["TitleKey"], data["TitleArgs"] = "page.title.logs", []interface{}{found.Meta.DisplayName}
	s.executeTemplate(w, r, "app_logs", data)
}

// appInstallPageHandler is `/apps/{slug}/install` — the install wizard, reached from the guide tab's
// „Telepites" button. It renders what the deploy page always rendered for a not-installed app; the
// difference is where its Vissza goes, which is now the app, not the list.
func (s *Server) appInstallPageHandler(w http.ResponseWriter, r *http.Request, slug string) {
	name := s.stackNameForSlug(slug)
	if name == "" {
		http.NotFound(w, r)
		return
	}
	// v0.320.0: part of the box, never installed — the address answers with the app's page, like a tab of a
	// not-installed app does. The deploy POST refuses it too (api deployStack, stacks.DeployStack).
	if s.cfg.IsProtectedStack(name) {
		http.Redirect(w, r, s.cfg.AppPageURL(slug), http.StatusFound)
		return
	}
	s.deployHandler(w, r, name)
}

// appPageDataKeysOwnedByTab are the keys that say WHICH page this is. deployPageData sets them for
// the install page; on a tab they would overwrite the tab's own title and nav highlight, so the merge
// keeps the tab's.
var appPageDataKeysOwnedByTab = map[string]bool{
	"Page": true, "Title": true, "TitleKey": true, "TitleArgs": true,
	"ActiveTab": true, "AppTabs": true, "Deployed": true, "AppOperational": true,
}

// mergeAppPageData copies src into dst, leaving the tab-owned keys alone. A key src does not set is
// never written, so the common data's value survives — which is what keeps EffectiveSubdomain (set
// always by appCommonData, only sometimes by deployPageData) correct on the settings tab.
func mergeAppPageData(dst, src map[string]interface{}) {
	for k, v := range src {
		if appPageDataKeysOwnedByTab[k] {
			continue
		}
		dst[k] = v
	}
}

// ── the old URLs ──────────────────────────────────────────────────────────────────────────────────

// redirectStackGETToAppTab answers an old `/stacks/{name}/{suffix}` GET with a 302 to the matching
// tab. The query string is carried through — `?raw=1` on the logs URL is the poller of a page that
// was open when the box updated, and `?flash=…` comes back from a save.
//
// 302, never 301: a 301 is cached by the browser for as long as it likes, and a wrong one cannot be
// taken back. These paths will be redirects for one release, not forever.
func (s *Server) redirectStackGETToAppTab(w http.ResponseWriter, r *http.Request, name, tab string) {
	slug := s.slugForStackName(name)
	if slug == "" {
		http.NotFound(w, r)
		return
	}
	dest := s.cfg.AppPageURL(slug)
	if tab != "" {
		dest += "/" + tab
	}
	if q := r.URL.RawQuery; q != "" {
		dest += "?" + q
	}
	http.Redirect(w, r, dest, http.StatusFound)
}

// redirectStackDeployGET sends the old settings/install URL to whichever of the two it now is: an
// installed app has a settings tab, a not-installed one has the install wizard.
func (s *Server) redirectStackDeployGET(w http.ResponseWriter, r *http.Request, name string) {
	st := s.stackBySlug(s.slugForStackName(name))
	if st == nil {
		http.NotFound(w, r)
		return
	}
	tab := appTabInstall
	if st.Deployed {
		tab = appTabSettings
	}
	s.redirectStackGETToAppTab(w, r, name, tab)
}

// appTabPathSuffix splits `{slug}` or `{slug}/{tab}` out of the path after `/apps/`, and reports
// whether the suffix is one this router knows. An unknown suffix is NOT a tab and must not be read as
// part of a slug — `/apps/grocy/nonsense` is a 404, not the app page for „grocy/nonsense".
func appTabPathSuffix(rest string) (slug, tab string, known bool) {
	rest = strings.Trim(rest, "/")
	if rest == "" {
		return "", "", false
	}
	slug, tail, found := strings.Cut(rest, "/")
	if !found {
		return slug, "", true
	}
	switch tail {
	case appTabSettings, appTabData, appTabGuide, appTabLogs, appTabInstall:
		return slug, tail, true
	}
	return slug, tail, false
}

// appPageURLFor is the household-facing URL of one tab, for a handler that redirects after a save.
func (s *Server) appPageURLFor(slug, tab string) string {
	dest := s.cfg.AppPageURL(slug)
	if tab != "" {
		dest += "/" + tab
	}
	return dest
}

// appPageURLForName is appPageURLFor keyed by stack name, for the two save handlers that know the
// name and not the slug. It falls back to the app list rather than inventing a URL.
func (s *Server) appPageURLForName(name, tab string) string {
	if slug := s.slugForStackName(name); slug != "" {
		return s.appPageURLFor(slug, tab)
	}
	return "/stacks"
}