package ui

import (
	"context"
	"strings"
	"time"

	"github.com/rivo/tview"

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

// serverChoice is a setting whose values come from the server: a dropdown of
// the names Radarr/Sonarr know (quality profiles, root folders), with "(none)"
// first. The value in use is kept as an option even when the server does not
// list it (or cannot be asked), so nothing is lost by opening the view.
type serverChoice struct {
	*tview.DropDown
	value  string   // the selected value; "" = none
	names  []string // from the server, in its order
	loaded bool     // names came from the server
	quiet  func() func()
	picked func(text string, index int) // SetOptions replaces it, so it is kept here
}

const noChoice = "(none)"

// newServerChoice makes the dropdown. quiet marks changes as not made by the
// user while the options are rebuilt; it returns the function that ends that.
func newServerChoice(label string, quiet func() func(), changed func()) *serverChoice {
	c := &serverChoice{DropDown: tview.NewDropDown().SetLabel(label), quiet: quiet}
	c.picked = func(_ string, i int) {
		c.value = c.valueAt(i)
		changed()
	}
	c.rebuild()
	return c
}

// options lists the values in the order shown: none, the server's names, and
// the value in use when the server does not have it.
func (c *serverChoice) options() []string {
	opts := append([]string{""}, c.names...)
	if c.value != "" && !contains(c.names, c.value) {
		opts = append(opts, c.value)
	}
	return opts
}

func (c *serverChoice) valueAt(i int) string {
	opts := c.options()
	if i < 0 || i >= len(opts) {
		return ""
	}
	return opts[i]
}

// rebuild puts the options into the dropdown and selects the value.
func (c *serverChoice) rebuild() {
	done := c.quiet()
	defer done()
	value := c.value
	var labels []string
	sel := 0
	for i, o := range c.options() {
		label := o
		switch {
		case o == "":
			label = noChoice
		case c.loaded && !contains(c.names, o):
			label = o + " (not on the server)"
		}
		labels = append(labels, label)
		if o == value {
			sel = i
		}
	}
	c.value = value
	c.SetOptions(labels, c.picked)
	c.SetCurrentOption(sel) // reports sel, which is value
}

// set selects a value.
func (c *serverChoice) set(value string) {
	c.value = strings.TrimSpace(value)
	c.rebuild()
}

// setNames replaces the server's names; nil with loaded false means they are
// not known.
func (c *serverChoice) setNames(names []string, loaded bool) {
	c.names, c.loaded = names, loaded
	c.rebuild()
}

func contains(list []string, s string) bool {
	for _, x := range list {
		if x == s {
			return true
		}
	}
	return false
}

// choicesDelay is how long typing in an address or API key pauses before the
// server is asked for its profiles and folders.
const choicesDelay = 700 * time.Millisecond

// scheduleChoices asks the service again once its address and key have not
// changed for choicesDelay.
func (v *settingsView) scheduleChoices(service string) {
	if t := v.choiceTimers[service]; t != nil {
		t.Stop()
	}
	v.choiceTimers[service] = time.AfterFunc(choicesDelay, func() {
		v.app.post(func() { v.loadChoices(service) })
	})
}

// loadChoices fills the profile and folder dropdowns of a service ("radarr" or
// "sonarr") from the server, using the address and key typed in the fields.
func (v *settingsView) loadChoices(service string) {
	profile, folder := v.choices[service+".profile"], v.choices[service+".folder"]
	url := strings.TrimSpace(v.inputs[service+".url"].GetText())
	key := strings.TrimSpace(v.inputs[service+".apikey"].GetText())
	v.choiceGen[service]++
	gen := v.choiceGen[service]
	if url == "" || key == "" {
		profile.setNames(nil, false)
		folder.setNames(nil, false)
		return
	}
	go func() {
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		profiles, folders, err := fetchChoices(ctx, url, key)
		v.app.post(func() { v.applyChoices(service, gen, profiles, folders, err) })
	}()
}

// fetchChoices asks a Radarr/Sonarr for its quality profile names and root
// folder paths.
func fetchChoices(ctx context.Context, url, key string) (profiles, folders []string, err error) {
	client := arr.NewClient(url, key)
	qp, err := client.QualityProfiles(ctx)
	if err != nil {
		return nil, nil, err
	}
	rf, err := client.RootFolders(ctx)
	if err != nil {
		return nil, nil, err
	}
	for _, p := range qp {
		profiles = append(profiles, p.Name)
	}
	for _, f := range rf {
		folders = append(folders, f.Path)
	}
	return profiles, folders, nil
}

// applyChoices puts what fetchChoices found into the dropdowns, unless the
// address or key changed since it was asked (gen).
func (v *settingsView) applyChoices(service string, gen int, profiles, folders []string, err error) {
	if v.choiceGen[service] != gen {
		return
	}
	profile, folder := v.choices[service+".profile"], v.choices[service+".folder"]
	if err != nil {
		profile.setNames(nil, false)
		folder.setNames(nil, false)
		name := map[string]string{"radarr": "Radarr", "sonarr": "Sonarr"}[service]
		if msg := err.Error(); v.choiceErr[service] != msg {
			v.choiceErr[service] = msg
			v.report("[yellow]" + name + ": quality profiles and root folders not loaded: " + tview.Escape(msg) + "[-]")
		}
		return
	}
	delete(v.choiceErr, service)
	profile.setNames(profiles, true)
	folder.setNames(folders, true)
}