// Package ui contains the tview user interface.
package ui

import (
	"fmt"
	"strings"
	"time"

	"github.com/gdamore/tcell/v2"
	"github.com/rivo/tview"

	"git.stinnesbeck.com/nils/arr-tui/internal/config"
	"git.stinnesbeck.com/nils/arr-tui/internal/radarr"
	"git.stinnesbeck.com/nils/arr-tui/internal/sabnzbd"
	"git.stinnesbeck.com/nils/arr-tui/internal/sonarr"
)

type view struct {
	key  rune
	name string
	body tview.Primitive
	// Optional hooks, called when the view becomes visible / hidden.
	onShow, onHide func()
}

// App is the top-level arr-tui application.
type App struct {
	app    *tview.Application
	tabs   *tview.TextView
	pages  *tview.Pages
	status *tview.TextView
	views  []view
	active int

	message  string
	overlays []overlay // dialogs and full-screen views stacked above the pages

	services *tview.TextView
	state    map[string]serviceState // keyed by service name
}

// serviceState is the last known connection state of a backend service.
type serviceState struct {
	known   bool
	version string
	err     error
}

// serviceNames fixes the order of the connection indicators.
var serviceNames = []string{"Radarr", "Sonarr", "SABnzbd"}

// overlay is a page stacked above the main views; focus is restored on close.
type overlay struct {
	page  string
	focus tview.Primitive
}

// New builds the application shell: a tab bar, one page per view and a status bar.
func New(cfg *config.Config) *App {
	a := &App{
		app:    tview.NewApplication(),
		tabs:   tview.NewTextView().SetDynamicColors(true),
		pages:  tview.NewPages(),
		status: tview.NewTextView().SetDynamicColors(true),

		services: tview.NewTextView().SetDynamicColors(true).SetTextAlign(tview.AlignRight),
		state:    map[string]serviceState{},
	}

	radarrClient := radarr.NewClient(cfg.Radarr.URL, cfg.Radarr.APIKey)
	sonarrClient := sonarr.NewClient(cfg.Sonarr.URL, cfg.Sonarr.APIKey)
	downloads := newDownloadsView(a, sabnzbd.NewClient(cfg.SABnzbd.URL, cfg.SABnzbd.APIKey),
		[]arrSource{
			{name: "Radarr", queue: radarrClient.Queue, remove: radarrClient.RemoveQueueItem},
			{name: "Sonarr", queue: sonarrClient.Queue, remove: sonarrClient.RemoveQueueItem},
		},
		time.Duration(cfg.UI.RefreshSeconds)*time.Second)
	a.views = []view{
		{key: '1', name: "Movies", body: newSearchView(a, radarrBackend{radarrClient}, cfg.Radarr).root},
		{key: '2', name: "Series", body: newSearchView(a, sonarrBackend{sonarrClient}, cfg.Sonarr).root},
		{key: '3', name: "Downloads", body: downloads.root, onShow: downloads.activate, onHide: downloads.deactivate},
		{key: '4', name: "Library", body: placeholder("Library (v0.2)")},
	}
	for i, v := range a.views {
		a.pages.AddPage(v.name, v.body, true, i == 0)
	}

	layout := tview.NewFlex().SetDirection(tview.FlexRow).
		AddItem(tview.NewFlex().
			AddItem(a.tabs, 0, 1, false).
			AddItem(a.services, 34, 0, false), 1, 0, false).
		AddItem(a.pages, 0, 1, true).
		AddItem(a.status, 1, 0, false)

	a.app.SetRoot(layout, true).EnableMouse(false)
	a.app.SetInputCapture(a.handleKey)
	a.switchTo(0)
	a.renderStatus()
	a.renderServices()
	return a
}

// SetService records the outcome of a request to a service and updates the
// connection indicators. UI goroutine only. A nil err means reachable.
func (a *App) SetService(name, version string, err error) {
	prev := a.state[name]
	if err == nil && version == "" {
		version = prev.version
	}
	a.state[name] = serviceState{known: true, version: version, err: err}
	a.renderServices()
}

func (a *App) renderServices() {
	var s string
	for _, n := range serviceNames {
		st := a.state[n]
		switch {
		case !st.known:
			s += "[gray]○ " + n + "[-]  "
		case st.err != nil:
			s += "[red]● " + n + "[-]  "
		default:
			s += "[green]●[-] " + n + "  "
		}
	}
	a.services.SetText(s)
}

// serviceSummary describes every service for the help screen.
func (a *App) serviceSummary() string {
	var b strings.Builder
	for _, n := range serviceNames {
		st := a.state[n]
		switch {
		case !st.known:
			fmt.Fprintf(&b, "[gray]○ %s: not contacted yet[-]\n", n)
		case st.err != nil:
			fmt.Fprintf(&b, "[red]● %s: %s[-]\n", n, tview.Escape(st.err.Error()))
		case st.version != "":
			fmt.Fprintf(&b, "[green]●[-] %s %s: connected\n", n, tview.Escape(st.version))
		default:
			fmt.Fprintf(&b, "[green]●[-] %s: connected\n", n)
		}
	}
	return b.String()
}

// SetMessage shows a message in the status bar. UI goroutine only; use
// post from other goroutines.
func (a *App) SetMessage(text string) {
	a.message = text
	a.renderStatus()
}

// post runs f on the UI goroutine and redraws. Safe to call from any goroutine.
func (a *App) post(f func()) {
	a.app.QueueUpdateDraw(f)
}

// Run starts the event loop and blocks until the application quits.
func (a *App) Run() error {
	return a.app.Run()
}

func (a *App) renderStatus() {
	hints := "[gray]?/F9 help · q quit · F1-F4 views · Tab panels · / search"
	if len(a.overlays) > 0 {
		hints = "[gray]Esc back · Ctrl+C quit"
	}
	if a.message == "" {
		a.status.SetText(hints)
		return
	}
	a.status.SetText(a.message + " [gray]│ " + hints)
}

// pushOverlay stacks p above everything and focuses focus.
func (a *App) pushOverlay(p, focus tview.Primitive) {
	name := fmt.Sprintf("overlay-%d", len(a.overlays))
	a.overlays = append(a.overlays, overlay{page: name, focus: a.app.GetFocus()})
	a.pages.AddPage(name, p, true, true)
	a.app.SetFocus(focus)
	a.renderStatus()
}

// openModal shows p centered above the current view.
func (a *App) openModal(p tview.Primitive, width, height int) {
	box := tview.NewFlex().
		AddItem(nil, 0, 1, false).
		AddItem(tview.NewFlex().SetDirection(tview.FlexRow).
			AddItem(nil, 0, 1, false).
			AddItem(p, height, 0, true).
			AddItem(nil, 0, 1, false), width, 0, true).
		AddItem(nil, 0, 1, false)
	a.pushOverlay(box, p)
}

// openFull shows p above the whole view area (the tab bar and status bar stay visible).
func (a *App) openFull(p tview.Primitive) {
	a.pushOverlay(p, p)
}

// closeModal removes the topmost overlay and restores the previous focus.
func (a *App) closeModal() {
	if len(a.overlays) == 0 {
		return
	}
	top := a.overlays[len(a.overlays)-1]
	a.overlays = a.overlays[:len(a.overlays)-1]
	a.pages.RemovePage(top.page)
	if top.focus != nil {
		a.app.SetFocus(top.focus)
	}
	a.renderStatus()
}

// confirm asks a yes/no question; yes runs only if the user picks Delete/Yes.
func (a *App) confirm(text string, yes func()) {
	lines := strings.Count(text, "\n") + 1 + len([]rune(text))/44
	m := tview.NewModal().
		SetText(text).
		AddButtons([]string{"Cancel", "Confirm"}). // Cancel first so a stray Enter is safe
		SetDoneFunc(func(i int, _ string) {
			a.closeModal()
			if i == 1 {
				yes()
			}
		})
	a.openModal(m, 60, 7+min(lines, 10))
}

// typing reports whether keystrokes belong to a text field or dialog and must
// not trigger global shortcuts.
func (a *App) typing() bool {
	if len(a.overlays) > 0 {
		return true
	}
	_, isInput := a.app.GetFocus().(*tview.InputField)
	return isInput
}

func (a *App) handleKey(ev *tcell.EventKey) *tcell.EventKey {
	if ev.Key() == tcell.KeyCtrlC {
		a.app.Stop()
		return nil
	}
	// Shortcuts that also work while typing in a search box. Not while a dialog is open.
	if len(a.overlays) == 0 {
		if ev.Key() == tcell.KeyF9 {
			a.showHelp()
			return nil
		}
		if i := a.viewShortcut(ev); i >= 0 && i < len(a.views) {
			a.switchTo(i)
			return nil
		}
	}
	if a.typing() {
		return ev
	}
	switch ev.Key() {
	case tcell.KeyRune:
		if ev.Rune() == 'q' {
			a.app.Stop()
			return nil
		}
		for i, v := range a.views {
			if ev.Rune() == v.key {
				a.switchTo(i)
				return nil
			}
		}
	}
	return ev
}

// viewShortcut returns the view index for F1-F4, or -1.
func (a *App) viewShortcut(ev *tcell.EventKey) int {
	if ev.Key() >= tcell.KeyF1 && ev.Key() <= tcell.KeyF12 {
		return int(ev.Key() - tcell.KeyF1)
	}
	return -1
}

func (a *App) switchTo(i int) {
	if hide := a.views[a.active].onHide; hide != nil && i != a.active {
		hide()
	}
	if show := a.views[i].onShow; show != nil && i != a.active {
		show()
	}
	a.active = i
	a.pages.SwitchToPage(a.views[i].name)
	a.renderTabs()
}

func (a *App) renderTabs() {
	var s string
	for i, v := range a.views {
		if i == a.active {
			s += fmt.Sprintf("[black:white] %c %s [-:-] ", v.key, v.name)
		} else {
			s += fmt.Sprintf("[gray] %c %s [-] ", v.key, v.name)
		}
	}
	a.tabs.SetText(s)
}

func placeholder(text string) tview.Primitive {
	return tview.NewTextView().SetText(text).SetTextAlign(tview.AlignCenter)
}