package ui

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"sync"
	"time"

	"github.com/gdamore/tcell/v2"
	"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/radarr"
)

const (
	searchDebounce = 300 * time.Millisecond
	minAutoSearch  = 2 // characters before the debounced search kicks in
)

// moviesView is the movie search / add screen backed by Radarr.
type moviesView struct {
	app    *App
	client *radarr.Client
	cfg    config.Arr

	root    *tview.Flex
	input   *tview.InputField
	list    *tview.List
	details *tview.TextView

	// UI-goroutine state.
	results []radarr.Movie
	timer   *time.Timer
	cancel  context.CancelFunc
	gen     int

	// Add-form options, loaded in the background.
	mu       sync.Mutex
	profiles []arr.QualityProfile
	folders  []arr.RootFolder
	optsErr  error
	loaded   bool
}

func newMoviesView(app *App, cfg config.Arr) *moviesView {
	v := &moviesView{
		app:     app,
		client:  radarr.NewClient(cfg.URL, cfg.APIKey),
		cfg:     cfg,
		input:   tview.NewInputField().SetLabel("Search: "),
		list:    tview.NewList().ShowSecondaryText(false),
		details: tview.NewTextView().SetDynamicColors(true).SetWordWrap(true),
	}
	v.list.SetBorder(true).SetTitle(" Movies ")
	v.details.SetBorder(true).SetTitle(" Details ")

	left := tview.NewFlex().SetDirection(tview.FlexRow).
		AddItem(v.input, 1, 0, true).
		AddItem(v.list, 0, 1, false)
	v.root = tview.NewFlex().
		AddItem(left, 0, 1, true).
		AddItem(v.details, 0, 1, false)

	v.input.SetChangedFunc(v.onSearchChanged)
	v.input.SetDoneFunc(func(key tcell.Key) {
		switch key {
		case tcell.KeyEnter:
			v.search(strings.TrimSpace(v.input.GetText()))
			v.app.app.SetFocus(v.list)
		case tcell.KeyEscape, tcell.KeyTab:
			v.app.app.SetFocus(v.list)
		}
	})
	v.input.SetInputCapture(func(ev *tcell.EventKey) *tcell.EventKey {
		if ev.Key() == tcell.KeyDown {
			v.app.app.SetFocus(v.list)
			return nil
		}
		return ev
	})

	v.list.SetChangedFunc(func(i int, _, _ string, _ rune) { v.showDetails(i) })
	v.list.SetSelectedFunc(func(i int, _, _ string, _ rune) { v.add(i) })
	v.list.SetInputCapture(func(ev *tcell.EventKey) *tcell.EventKey {
		if ev.Key() != tcell.KeyRune {
			return ev
		}
		switch ev.Rune() {
		case '/':
			v.app.app.SetFocus(v.input)
			return nil
		case 'a':
			v.add(v.list.GetCurrentItem())
			return nil
		}
		return ev
	})

	go v.loadOptions()
	return v
}

// loadOptions checks the connection and fetches the data the add form needs.
func (v *moviesView) loadOptions() {
	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
	defer cancel()

	var (
		profiles []arr.QualityProfile
		folders  []arr.RootFolder
	)
	status, err := v.client.SystemStatus(ctx)
	if err == nil {
		profiles, err = v.client.QualityProfiles(ctx)
	}
	if err == nil {
		folders, err = v.client.RootFolders(ctx)
	}

	v.mu.Lock()
	v.profiles, v.folders, v.optsErr, v.loaded = profiles, folders, err, true
	v.mu.Unlock()

	v.app.post(func() {
		if err != nil {
			v.app.SetMessage("[red]Radarr: " + tview.Escape(err.Error()))
			return
		}
		v.app.SetMessage(fmt.Sprintf("[green]Radarr %s connected", tview.Escape(status.Version)))
	})
}

func (v *moviesView) options() ([]arr.QualityProfile, []arr.RootFolder, error) {
	v.mu.Lock()
	defer v.mu.Unlock()
	if !v.loaded {
		return nil, nil, errors.New("still connecting to Radarr")
	}
	return v.profiles, v.folders, v.optsErr
}

// onSearchChanged debounces typing into a search.
func (v *moviesView) onSearchChanged(text string) {
	if v.timer != nil {
		v.timer.Stop()
	}
	text = strings.TrimSpace(text)
	if len([]rune(text)) < minAutoSearch {
		v.invalidate()
		if text == "" {
			v.setResults(nil)
		}
		return
	}
	gen := v.invalidate()
	ctx, cancel := context.WithCancel(context.Background())
	v.cancel = cancel
	v.timer = time.AfterFunc(searchDebounce, func() { v.run(ctx, gen, text) })
}

// invalidate cancels any in-flight search and returns the new generation.
func (v *moviesView) invalidate() int {
	if v.cancel != nil {
		v.cancel()
		v.cancel = nil
	}
	v.gen++
	return v.gen
}

// search runs a search immediately (UI goroutine).
func (v *moviesView) search(text string) {
	if v.timer != nil {
		v.timer.Stop()
	}
	gen := v.invalidate()
	if text == "" {
		v.setResults(nil)
		return
	}
	ctx, cancel := context.WithCancel(context.Background())
	v.cancel = cancel
	go v.run(ctx, gen, text)
}

// run performs the request off the UI goroutine and applies fresh results.
func (v *moviesView) run(ctx context.Context, gen int, term string) {
	v.app.post(func() {
		if gen == v.gen {
			v.app.SetMessage("Searching…")
		}
	})
	movies, err := v.client.Lookup(ctx, term)
	if errors.Is(err, context.Canceled) {
		return
	}
	v.app.post(func() {
		if gen != v.gen {
			return // superseded by a newer search
		}
		if err != nil {
			v.app.SetMessage("[red]Search failed: " + tview.Escape(err.Error()))
			return
		}
		v.app.SetMessage(fmt.Sprintf("%d results for %q", len(movies), tview.Escape(term)))
		v.setResults(movies)
	})
}

// setResults replaces the list contents (UI goroutine).
func (v *moviesView) setResults(movies []radarr.Movie) {
	v.results = movies
	v.render(0)
}

// render rebuilds the list, selecting index sel.
func (v *moviesView) render(sel int) {
	v.list.Clear()
	for _, m := range v.results {
		v.list.AddItem(movieLabel(m), "", 0, nil)
	}
	if len(v.results) == 0 {
		v.details.SetText("")
		return
	}
	sel = min(max(sel, 0), len(v.results)-1)
	v.list.SetCurrentItem(sel)
	v.showDetails(sel)
}

func (v *moviesView) showDetails(i int) {
	if i < 0 || i >= len(v.results) {
		v.details.SetText("")
		return
	}
	v.details.SetText(movieDetails(v.results[i])).ScrollToBeginning()
}

// add opens the add dialog for the result at index i.
func (v *moviesView) add(i int) {
	if i < 0 || i >= len(v.results) {
		return
	}
	m := v.results[i]
	if m.InLibrary() {
		v.app.SetMessage(fmt.Sprintf("[yellow]%s is already in Radarr", tview.Escape(m.Title)))
		return
	}
	profiles, folders, err := v.options()
	switch {
	case err != nil:
		v.app.SetMessage("[red]Radarr: " + tview.Escape(err.Error()))
		return
	case len(profiles) == 0 || len(folders) == 0:
		v.app.SetMessage("[red]Radarr has no quality profiles or root folders configured")
		return
	}

	profileNames := make([]string, len(profiles))
	for i, p := range profiles {
		profileNames[i] = p.Name
	}
	folderPaths := make([]string, len(folders))
	for i, f := range folders {
		folderPaths[i] = f.Path
	}

	const (
		lProfile = "Quality profile"
		lFolder  = "Root folder"
		lMonitor = "Monitored"
		lSearch  = "Search now"
	)
	form := tview.NewForm().
		AddDropDown(lProfile, profileNames, profileIndex(profiles, v.cfg.DefaultQualityProfile), nil).
		AddDropDown(lFolder, folderPaths, folderIndex(folders, v.cfg.DefaultRootFolder), nil).
		AddCheckbox(lMonitor, true, nil).
		AddCheckbox(lSearch, true, nil)
	form.AddButton("Add", func() {
		opts := radarr.AddOptions{
			QualityProfileID: profiles[selected(form, lProfile)].ID,
			RootFolderPath:   folders[selected(form, lFolder)].Path,
			Monitored:        form.GetFormItemByLabel(lMonitor).(*tview.Checkbox).IsChecked(),
			SearchNow:        form.GetFormItemByLabel(lSearch).(*tview.Checkbox).IsChecked(),
		}
		v.app.closeModal()
		v.doAdd(m, opts)
	})
	form.AddButton("Cancel", v.app.closeModal)
	form.SetCancelFunc(v.app.closeModal)
	form.SetBorder(true).SetTitle(" Add " + tview.Escape(m.Title) + " ")

	v.app.openModal(form, 60, 13)
}

func (v *moviesView) doAdd(m radarr.Movie, opts radarr.AddOptions) {
	v.app.SetMessage("Adding " + tview.Escape(m.Title) + "…")
	go func() {
		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
		defer cancel()
		created, err := v.client.AddMovie(ctx, m, opts)
		v.app.post(func() {
			if err != nil {
				v.app.SetMessage("[red]Add failed: " + tview.Escape(err.Error()))
				return
			}
			msg := "[green]Added " + tview.Escape(m.Title)
			if opts.SearchNow {
				msg += " and started a search"
			}
			v.app.SetMessage(msg)
			v.markAdded(created)
		})
	}()
}

// markAdded flags the matching result as in the library, keeping the selection.
func (v *moviesView) markAdded(created radarr.Movie) {
	for i := range v.results {
		if v.results[i].TMDBID == created.TMDBID {
			v.results[i].ID = created.ID
			v.results[i].Monitored = created.Monitored
		}
	}
	v.render(v.list.GetCurrentItem())
}

// selected returns the chosen index of the dropdown labelled label.
func selected(form *tview.Form, label string) int {
	i, _ := form.GetFormItemByLabel(label).(*tview.DropDown).GetCurrentOption()
	return i
}