package ui

import (
	"context"
	"fmt"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/rivo/tview"

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

// settingsValues are the settings as shown in the Config view.
type settingsValues struct {
	radarrURL, radarrKey, radarrProfile, radarrFolder string
	sonarrURL, sonarrKey, sonarrProfile, sonarrFolder string
	sabURL, sabKey                                    string
	refresh                                           string // seconds, as typed
	covers                                            bool
	coverStyle                                        string
	notify, bell                                      bool
	theme                                             string
}

var (
	coverStyles = []string{"auto", "kitty", "sextant", "quadrant", "cells"}
	themes      = []string{"auto", "dark", "light"}
)

// settingsFrom reads the settings in use.
func settingsFrom(c *config.Config) settingsValues {
	style, th := c.UI.CoverStyle, c.UI.Theme
	if style == "" {
		style = "auto"
	}
	if th == "" {
		th = "auto"
	}
	return settingsValues{
		radarrURL: c.Radarr.URL, radarrKey: c.Radarr.APIKey,
		radarrProfile: c.Radarr.DefaultQualityProfile, radarrFolder: c.Radarr.DefaultRootFolder,
		sonarrURL: c.Sonarr.URL, sonarrKey: c.Sonarr.APIKey,
		sonarrProfile: c.Sonarr.DefaultQualityProfile, sonarrFolder: c.Sonarr.DefaultRootFolder,
		sabURL: c.SABnzbd.URL, sabKey: c.SABnzbd.APIKey,
		refresh: strconv.Itoa(c.UI.RefreshSeconds),
		covers:  c.UI.ShowCovers(), coverStyle: style,
		notify: c.UI.ShouldNotifyDownloads(), bell: c.UI.Bell,
		theme: th,
	}
}

// applySettings returns raw (the config file's contents) with the edited
// values. Settings the environment overrides are left as the file has them, so
// a value that only came from the environment is never written to disk. The
// result is checked the way the program checks its configuration.
func applySettings(raw config.Config, v settingsValues, overridden map[string]string) (config.Config, error) {
	set := func(key string, dst *string, value string) {
		if _, env := overridden[key]; !env {
			*dst = strings.TrimSpace(value)
		}
	}
	set("radarr.url", &raw.Radarr.URL, v.radarrURL)
	set("radarr.apikey", &raw.Radarr.APIKey, v.radarrKey)
	set("sonarr.url", &raw.Sonarr.URL, v.sonarrURL)
	set("sonarr.apikey", &raw.Sonarr.APIKey, v.sonarrKey)
	set("sabnzbd.url", &raw.SABnzbd.URL, v.sabURL)
	set("sabnzbd.apikey", &raw.SABnzbd.APIKey, v.sabKey)
	raw.Radarr.DefaultQualityProfile = strings.TrimSpace(v.radarrProfile)
	raw.Radarr.DefaultRootFolder = strings.TrimSpace(v.radarrFolder)
	raw.Sonarr.DefaultQualityProfile = strings.TrimSpace(v.sonarrProfile)
	raw.Sonarr.DefaultRootFolder = strings.TrimSpace(v.sonarrFolder)

	n, err := strconv.Atoi(strings.TrimSpace(v.refresh))
	if err != nil || n < 1 || n > 3600 {
		return raw, fmt.Errorf("refresh interval: %q is not a number of seconds between 1 and 3600", v.refresh)
	}
	raw.UI.RefreshSeconds = n
	// Defaults stay out of the file unless the file already named them.
	raw.UI.Covers = boolSetting(raw.UI.Covers, v.covers, true)
	raw.UI.NotifyDownloads = boolSetting(raw.UI.NotifyDownloads, v.notify, true)
	raw.UI.Bell = v.bell
	raw.UI.CoverStyle = v.coverStyle
	if v.coverStyle == "auto" {
		raw.UI.CoverStyle = ""
	}
	raw.UI.Theme = v.theme
	if v.theme == "auto" {
		raw.UI.Theme = ""
	}

	if _, err := raw.Effective(os.Getenv); err != nil {
		return raw, err
	}
	return raw, nil
}

// boolSetting keeps an optional boolean out of the file while it equals its
// default and was not in the file before.
func boolSetting(old *bool, value, def bool) *bool {
	if old == nil && value == def {
		return nil
	}
	return &value
}

// settingsView edits the configuration file's settings. Everything applies
// right after saving.
type settingsView struct {
	app  *App
	root *tview.Flex

	form     *tview.Form   // every field, one below the other, with section headings
	testItem *formAction   // the Test button, below the service settings
	actions  *tview.Form   // the buttons below it
	groups   []*tview.Form // keyboard order: the fields, then the buttons
	status   *tview.TextView

	inputs  map[string]*tview.InputField // by setting key, e.g. "radarr.url"
	choices map[string]*serverChoice     // "radarr.profile", "radarr.folder", ...

	// Loading the choices from the servers, per service.
	choiceTimers map[string]*time.Timer
	choiceGen    map[string]int
	choiceErr    map[string]string // last error reported, so it is not repeated
	refresh      *tview.InputField
	covers       *tview.Checkbox
	style        *tview.DropDown
	theme        *tview.DropDown
	notify       *tview.Checkbox
	bell         *tview.Checkbox
	showKeys     *tview.Checkbox
	overridden   map[string]string
	dirty        bool
	filling      bool // set while the fields are filled, so that does not count as an edit
}

func settingsHints() string {
	return "↑↓ move through the fields · Space toggles or presses a button · Tab jumps between fields and Save/Revert"
}

func newSettingsView(app *App) *settingsView {
	v := &settingsView{app: app, inputs: map[string]*tview.InputField{}, overridden: config.Overrides(os.Getenv),
		choices: map[string]*serverChoice{}, choiceTimers: map[string]*time.Timer{}, choiceGen: map[string]int{}, choiceErr: map[string]string{}}
	quiet := func() func() {
		was := v.filling
		v.filling = true
		return func() { v.filling = was }
	}

	// One form with every field below the other: ↑↓ moves through all of them
	// and the form scrolls to keep the focused field in view.
	f := tview.NewForm().SetItemPadding(0)
	f.SetBorder(true).SetTitle(" Settings ")
	f.SetBorderPadding(0, 0, 1, 1) // one row per field
	v.form = f

	input := func(label, key string) {
		in := tview.NewInputField().SetLabel(label)
		if strings.HasSuffix(key, ".apikey") {
			in.SetMaskCharacter('*')
		}
		if _, ok := v.overridden[key]; ok {
			in.SetLabel(label + " (env)")
			in.SetDisabled(true)
		}
		in.SetChangedFunc(func(string) {
			v.edited()
			// New address or key: ask that server for its profiles and folders.
			if service, field, _ := strings.Cut(key, "."); service != "sabnzbd" && !v.filling && (field == "url" || field == "apikey") {
				v.scheduleChoices(service)
			}
		})
		f.AddFormItem(in)
		v.inputs[key] = in
	}
	choice := func(label, key string) {
		c := newServerChoice(label, quiet, v.edited)
		f.AddFormItem(c)
		v.choices[key] = c
	}
	service := func(title, name string, withDefaults bool) {
		f.AddFormItem(newFormHeading(title))
		input("Address", name+".url")
		input("API key", name+".apikey")
		if withDefaults {
			choice("Default quality profile", name+".profile")
			choice("Default root folder", name+".folder")
		}
	}
	service("Radarr", "radarr", true)
	service("Sonarr", "sonarr", true)
	service("SABnzbd", "sabnzbd", false)
	// Right below the connection settings it checks.
	v.testItem = newFormAction("Test", v.test)
	f.AddFormItem(v.testItem)

	f.AddFormItem(newFormHeading("Interface"))
	v.refresh = tview.NewInputField().SetLabel("Downloads refresh (seconds)").SetFieldWidth(6)
	v.refresh.SetChangedFunc(func(string) { v.edited() })
	f.AddFormItem(v.refresh)
	v.covers = tview.NewCheckbox().SetLabel("Posters").SetChangedFunc(func(bool) { v.edited() })
	f.AddFormItem(v.covers)
	v.style = tview.NewDropDown().SetLabel("Poster style").SetOptions(coverStyles, func(string, int) { v.edited() })
	f.AddFormItem(v.style)
	v.theme = tview.NewDropDown().SetLabel("Theme").SetOptions(themes, func(string, int) { v.edited() })
	f.AddFormItem(v.theme)
	v.notify = tview.NewCheckbox().SetLabel("Notify about finished downloads").SetChangedFunc(func(bool) { v.edited() })
	f.AddFormItem(v.notify)
	v.bell = tview.NewCheckbox().SetLabel("Ring the terminal bell too").SetChangedFunc(func(bool) { v.edited() })
	f.AddFormItem(v.bell)
	v.showKeys = tview.NewCheckbox().SetLabel("Show API keys").SetChangedFunc(func(shown bool) { v.maskKeys(!shown) })
	f.AddFormItem(v.showKeys)

	v.actions = tview.NewForm().SetItemPadding(0)
	v.actions.SetBorder(true).SetTitle(" Actions ")
	v.actions.SetBorderPadding(0, 0, 1, 1)
	v.actions.SetButtonsAlign(tview.AlignCenter)
	v.actions.AddButton("Save", v.save)
	v.actions.AddButton("Revert", v.revert)

	v.status = tview.NewTextView().SetDynamicColors(true).SetWordWrap(true)
	v.status.SetBorder(true).SetTitle(" Result ")

	left := tview.NewFlex().SetDirection(tview.FlexRow).
		AddItem(v.form, 0, 1, true).
		AddItem(v.actions, 4, 0, false)
	v.root = tview.NewFlex().AddItem(left, 0, 3, true).AddItem(v.status, 0, 2, false)

	v.groups = []*tview.Form{v.form, v.actions}
	for i, g := range v.groups {
		i := i
		arrowNavigation(g, func() {}, &browseHooks{
			// ↓ past the last field reaches the buttons, ↑ from them goes back.
			edge: func(down bool) bool {
				if down && i+1 < len(v.groups) {
					v.focusGroup(i+1, false)
					return true
				}
				if !down && i > 0 {
					v.focusGroup(i-1, true)
					return true
				}
				return false
			},
			tab: func(dir int) bool {
				v.focusGroup((i+dir+len(v.groups))%len(v.groups), false)
				return true
			},
		})
	}
	v.fill(settingsFrom(app.cfg))
	v.maskKeys(true)
	v.describe()
	return v
}

// focusGroup moves the focus to a group, to its first or last field.
func (v *settingsView) focusGroup(i int, last bool) {
	// tview only blurs the leaf that had the focus, not the other items of a
	// form or the form itself; a form that keeps thinking it has focus would
	// take the key presses.
	for j, other := range v.groups {
		if j != i {
			blurForm(other)
		}
	}
	g := v.groups[i]
	idx := firstFocusable(g)
	if last {
		idx = g.GetFormItemCount() + g.GetButtonCount() - 1
	}
	g.SetFocus(idx)
	v.app.app.SetFocus(g)
}

// blurForm takes the focus away from a form and everything in it.
func blurForm(f *tview.Form) {
	for i := 0; i < f.GetFormItemCount(); i++ {
		f.GetFormItem(i).Blur()
	}
	for i := 0; i < f.GetButtonCount(); i++ {
		f.GetButton(i).Blur()
	}
	f.Blur()
}

func (v *settingsView) edited() {
	if !v.filling {
		v.dirty = true
	}
}

// maskKeys hides or shows the API keys.
func (v *settingsView) maskKeys(hide bool) {
	for key, in := range v.inputs {
		if strings.HasSuffix(key, ".apikey") {
			if hide {
				in.SetMaskCharacter('*')
			} else {
				in.SetMaskCharacter(0)
			}
		}
	}
}

// fill puts the values into the fields.
func (v *settingsView) fill(s settingsValues) {
	v.filling = true
	defer func() { v.filling = false }()
	set := map[string]string{
		"radarr.url": s.radarrURL, "radarr.apikey": s.radarrKey,
		"sonarr.url": s.sonarrURL, "sonarr.apikey": s.sonarrKey,
		"sabnzbd.url": s.sabURL, "sabnzbd.apikey": s.sabKey,
	}
	for key, value := range set {
		v.inputs[key].SetText(value)
	}
	for key, value := range map[string]string{
		"radarr.profile": s.radarrProfile, "radarr.folder": s.radarrFolder,
		"sonarr.profile": s.sonarrProfile, "sonarr.folder": s.sonarrFolder,
	} {
		v.choices[key].set(value)
	}
	v.refresh.SetText(s.refresh)
	v.covers.SetChecked(s.covers)
	for i, name := range coverStyles {
		if name == s.coverStyle {
			v.style.SetCurrentOption(i)
		}
	}
	for i, name := range themes {
		if name == s.theme {
			v.theme.SetCurrentOption(i)
		}
	}
	v.notify.SetChecked(s.notify)
	v.bell.SetChecked(s.bell)
	v.dirty = false
}

// read collects the values from the fields.
func (v *settingsView) read() settingsValues {
	text := func(key string) string {
		if c, ok := v.choices[key]; ok {
			return c.value
		}
		return v.inputs[key].GetText()
	}
	i, _ := v.style.GetCurrentOption()
	style := "auto"
	if i >= 0 && i < len(coverStyles) {
		style = coverStyles[i]
	}
	th := "auto"
	if i, _ := v.theme.GetCurrentOption(); i >= 0 && i < len(themes) {
		th = themes[i]
	}
	return settingsValues{
		radarrURL: text("radarr.url"), radarrKey: text("radarr.apikey"),
		radarrProfile: text("radarr.profile"), radarrFolder: text("radarr.folder"),
		sonarrURL: text("sonarr.url"), sonarrKey: text("sonarr.apikey"),
		sonarrProfile: text("sonarr.profile"), sonarrFolder: text("sonarr.folder"),
		sabURL: text("sabnzbd.url"), sabKey: text("sabnzbd.apikey"),
		refresh: v.refresh.GetText(),
		covers:  v.covers.IsChecked(), coverStyle: style,
		notify: v.notify.IsChecked(), bell: v.bell.IsChecked(),
		theme: th,
	}
}

// describe writes the standing information into the result box.
func (v *settingsView) describe() {
	var b strings.Builder
	if v.app.cfgPath == "" {
		b.WriteString("[yellow]No config file is known, changes cannot be saved.[-]\n")
	} else {
		b.WriteString("Config file: " + tview.Escape(v.app.cfgPath) + "\n")
	}
	b.WriteString("Changes take effect when you save; nothing needs a restart.\n")
	if !v.app.cfg.AnyConfigured() {
		b.WriteString("[yellow]No service is set up yet.[-] Enter the address and API key of Radarr, Sonarr and/or SABnzbd (Settings → General in each app), then Save. A service left empty is simply not used.\n")
	}
	if len(v.overridden) > 0 {
		var names []string
		for _, env := range v.overridden {
			names = append(names, env)
		}
		b.WriteString("[gray]Greyed-out fields come from the environment (" + strings.Join(names, ", ") + ") and are not written to the file.[-]\n")
	}
	v.status.SetText(b.String())
}

// activate refreshes the fields when the view is shown, unless they hold unsaved edits.
func (v *settingsView) activate() {
	if !v.dirty {
		v.fill(settingsFrom(v.app.cfg))
	}
	v.loadChoices("radarr")
	v.loadChoices("sonarr")
	v.focusGroup(0, false)
}

// report appends a line to the result box.
func (v *settingsView) report(line string) {
	fmt.Fprintln(v.status, line)
	v.status.ScrollToEnd()
}

func (v *settingsView) revert() {
	v.fill(settingsFrom(v.app.cfg))
	v.loadChoices("radarr")
	v.loadChoices("sonarr")
	v.describe()
	v.report("[green]Reverted to the saved settings.[-]")
}

// test checks the three services with the values in the fields, without saving.
func (v *settingsView) test() {
	s := v.read()
	v.describe()
	v.report("Testing the connections…")
	type probeFn func(ctx context.Context) (string, error)
	tests := []struct {
		name string
		run  probeFn
	}{
		{"Radarr", func(ctx context.Context) (string, error) {
			st, err := arr.NewClient(strings.TrimSpace(s.radarrURL), strings.TrimSpace(s.radarrKey)).SystemStatus(ctx)
			return st.Version, err
		}},
		{"Sonarr", func(ctx context.Context) (string, error) {
			st, err := arr.NewClient(strings.TrimSpace(s.sonarrURL), strings.TrimSpace(s.sonarrKey)).SystemStatus(ctx)
			return st.Version, err
		}},
		{"SABnzbd", func(ctx context.Context) (string, error) {
			return sabnzbd.NewClient(strings.TrimSpace(s.sabURL), strings.TrimSpace(s.sabKey)).Version(ctx)
		}},
	}
	for _, t := range tests {
		go func() {
			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
			defer cancel()
			version, err := t.run(ctx)
			v.app.post(func() {
				if err != nil {
					v.report("[red]✗ " + t.name + ": " + tview.Escape(err.Error()) + "[-]")
					return
				}
				v.report("[green]✓ " + t.name + " " + tview.Escape(version) + " answers[-]")
			})
		}()
	}
}

// save writes the config file and applies the settings.
func (v *settingsView) save() {
	v.describe()
	if v.app.cfgPath == "" || v.app.cfgFile == nil {
		v.report("[red]There is no config file to save to.[-]")
		return
	}
	raw, err := applySettings(*v.app.cfgFile, v.read(), v.overridden)
	if err != nil {
		v.report("[red]Not saved: " + tview.Escape(err.Error()) + "[-]")
		return
	}
	if err := config.Save(v.app.cfgPath, &raw); err != nil {
		v.report("[red]Not saved: " + tview.Escape(err.Error()) + "[-]")
		return
	}
	effective, err := raw.Effective(os.Getenv)
	if err != nil { // cannot happen: applySettings validated it
		v.report("[red]Saved, but not applied: " + tview.Escape(err.Error()) + "[-]")
		return
	}
	v.app.cfgFile = &raw
	v.app.applyConfig(effective)
	v.dirty = false
	v.describe() // what it says may depend on the settings (e.g. nothing set up yet)
	v.report("[green]Saved to " + tview.Escape(v.app.cfgPath) + " and applied.[-]")
	v.app.Notify(levelSuccess, "Settings saved")
}