package ui

import (
	"context"
	"fmt"
	"slices"
	"strings"
	"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/radarr"
	"git.stinnesbeck.com/nils/arr-tui/internal/sonarr"
)

type libKind int

const (
	kindMovies libKind = iota
	kindSeries
)

func (k libKind) String() string {
	if k == kindMovies {
		return "Movies"
	}
	return "Series"
}

func (k libKind) service() string {
	if k == kindMovies {
		return "Radarr"
	}
	return "Sonarr"
}

// libItem is one row of the library: a movie or a series in display form.
type libItem struct {
	id        int
	title     string // plain, used for sorting and filtering
	label     string // escaped title with year
	monitored bool
	have      bool // at least one file on disk
	missing   bool // monitored and not complete
	status    string
	size      string
	details   detailText
	cover     coverRef
	movie     *radarr.Movie
	series    *sonarr.Series
	// File properties for the attribute filter. For series they are fetched on
	// demand, attrsKnown tells whether that has happened.
	attrs      []arr.FileAttrs
	attrsKnown bool
}

var libFilters = []struct {
	name  string
	match func(libItem) bool
}{
	{"all", func(libItem) bool { return true }},
	{"missing", func(i libItem) bool { return i.missing }},
	{"downloaded", func(i libItem) bool { return i.have }},
	{"monitored", func(i libItem) bool { return i.monitored }},
	{"unmonitored", func(i libItem) bool { return !i.monitored }},
}

func monMark(monitored bool) string {
	if monitored {
		return "[green]●[-]"
	}
	return "[gray]○[-]"
}

func sizeOrBlank(b int64) string {
	if b <= 0 {
		return ""
	}
	return formatSize(b)
}

func newMovieItem(m radarr.Movie) libItem {
	it := libItem{
		attrsKnown: true,
		id:         m.ID, title: m.Title, monitored: m.Monitored, have: m.HasFile,
		missing: m.Monitored && !m.HasFile && m.IsAvailable,
		size:    sizeOrBlank(m.SizeOnDisk), movie: &m,
	}
	if m.HasFile && m.MovieFile != nil {
		it.attrs = []arr.FileAttrs{m.MovieFile.Attrs()}
	}
	it.label = tview.Escape(m.Title)
	if m.Year > 0 {
		it.label += fmt.Sprintf(" (%d)", m.Year)
	}
	switch {
	case m.HasFile:
		it.status = "[green]✓ " + tview.Escape(m.QualityName())
	case !m.Monitored:
		it.status = "[gray]unmonitored"
	case !m.IsAvailable:
		it.status = "[gray]not released"
	default:
		it.status = "[yellow]missing"
	}
	it.details = movieDetails(m)
	it.details.head += monitoredLine(m.Monitored) + sizeLine(m.SizeOnDisk)
	if path := pathLine(m.Path); path != "" {
		it.details.plot += "\n\n" + path
	}
	return it
}

func newSeriesItem(s sonarr.Series) libItem {
	st := s.Statistics
	it := libItem{
		id: s.ID, title: s.Title, monitored: s.Monitored, have: st.EpisodeFileCount > 0,
		missing: s.Monitored && st.EpisodeFileCount < st.EpisodeCount,
		size:    sizeOrBlank(st.SizeOnDisk), series: &s,
	}
	it.attrsKnown = st.EpisodeFileCount == 0 // nothing to fetch for series without files
	it.label = tview.Escape(s.Title)
	if s.Year > 0 {
		it.label += fmt.Sprintf(" (%d)", s.Year)
	}
	counts := fmt.Sprintf("%d/%d", st.EpisodeFileCount, st.EpisodeCount)
	switch {
	case !s.Monitored:
		it.status = "[gray]" + counts + " unmonitored"
	case st.EpisodeFileCount >= st.EpisodeCount:
		it.status = "[green]" + counts
	default:
		it.status = "[yellow]" + counts
	}
	it.details = seriesDetails(s)
	it.details.head += monitoredLine(s.Monitored) + sizeLine(st.SizeOnDisk)
	return it
}

func monitoredLine(m bool) string {
	if m {
		return "Monitored: yes\n"
	}
	return "Monitored: [gray]no[-]\n"
}

func sizeLine(b int64) string {
	if b <= 0 {
		return ""
	}
	return "Size on disk: " + formatSize(b) + "\n"
}

func pathLine(p string) string {
	if p == "" {
		return ""
	}
	return "Path: " + tview.Escape(p) + "\n"
}

// filterItems applies the filter preset, the text filter and the file
// property filter, sorted by title. Items whose file properties are not known
// yet do not match an active property filter.
func filterItems(items []libItem, filter int, text string, af attrFilter) []libItem {
	text = strings.ToLower(strings.TrimSpace(text))
	var out []libItem
	for _, it := range items {
		if !libFilters[filter].match(it) || !strings.Contains(strings.ToLower(it.title), text) {
			continue
		}
		if !af.active() || af.match(it.attrs) {
			out = append(out, it)
		}
	}
	slices.SortFunc(out, func(a, b libItem) int {
		return strings.Compare(strings.ToLower(a.title), strings.ToLower(b.title))
	})
	return out
}

// libPane is one of the two lists (movies, series) of the library view.
type libPane struct {
	kind   libKind
	table  *tview.Table
	all    []libItem
	shown  []libItem
	loaded bool
	err    error
	gen    int    // invalidates stale loads
	text   string // text filter, set with / while this pane is the current one
	// Each list has its own filters.
	filter int        // status preset, index into libFilters
	attr   attrFilter // file properties
}

// libraryView shows the movies of Radarr above the series of Sonarr, with the
// details of the selected item on the right.
type libraryView struct {
	app    *App
	radarr *radarr.Client
	sonarr *sonarr.Client

	root    *tview.Flex
	header  *tview.TextView
	input   *tview.InputField
	details *detailPane
	panes   [2]*libPane

	// UI-goroutine state.
	cur libKind // the pane that has (or last had) focus

	// File properties of series, fetched on demand and cached. An entry is
	// reused while the series' file count and size stay the same.
	seriesFiles map[int]seriesFiles
	fileGen     int // invalidates running fetches
	filePending int

	refreshDialog func() // re-evaluates the options of the open filter dialog
}

type seriesFiles struct {
	count int
	size  int64
	attrs []arr.FileAttrs
}

func newLibraryView(app *App, r *radarr.Client, s *sonarr.Client) *libraryView {
	v := &libraryView{
		app: app, radarr: r, sonarr: s,
		header:  tview.NewTextView().SetDynamicColors(true),
		input:   tview.NewInputField().SetLabel("Filter Movies: ").SetFieldWidth(0),
		details: newDetailPane(app),

		seriesFiles: map[int]seriesFiles{},
	}

	lists := tview.NewFlex().SetDirection(tview.FlexRow) // movies above series
	for _, kind := range []libKind{kindMovies, kindSeries} {
		p := &libPane{kind: kind, table: tview.NewTable().SetSelectable(true, false).SetFixed(1, 0)}
		p.table.SetBorder(true)
		p.table.SetSelectionChangedFunc(func(int, int) { v.renderDetails() })
		p.table.SetSelectedFunc(func(int, int) { v.open() })
		p.table.SetInputCapture(v.handleKey)
		p.table.SetFocusFunc(func() {
			v.cur = kind
			v.input.SetLabel("Filter " + kind.String() + ": ")
			v.input.SetText(p.text)
			p.table.SetBorderColor(tcell.ColorYellow)
			v.renderDetails()
		})
		p.table.SetBlurFunc(func() { p.table.SetBorderColor(tview.Styles.BorderColor) })
		v.panes[kind] = p
		lists.AddItem(p.table, 0, 1, kind == kindMovies)
	}
	v.root = tview.NewFlex().SetDirection(tview.FlexRow).
		AddItem(v.header, 1, 0, false).
		AddItem(v.input, 1, 0, false).
		AddItem(tview.NewFlex().
			AddItem(lists, 0, 3, true).
			AddItem(v.details, 0, 2, false), 0, 1, true)

	v.input.SetChangedFunc(func(text string) {
		v.pane().text = text // the text filter only acts on the current pane
		v.render()
	})
	v.input.SetDoneFunc(func(tcell.Key) { v.app.app.SetFocus(v.pane().table) })
	v.render()
	return v
}

func (v *libraryView) pane() *libPane { return v.panes[v.cur] }

func (v *libraryView) handleKey(ev *tcell.EventKey) *tcell.EventKey {
	switch ev.Key() {
	case tcell.KeyTab, tcell.KeyBacktab:
		v.app.app.SetFocus(v.panes[1-v.cur].table)
		return nil
	case tcell.KeyRune:
		switch ev.Rune() {
		case '/':
			v.app.app.SetFocus(v.input)
		case 'f':
			p := v.pane()
			p.filter = (p.filter + 1) % len(libFilters)
			v.render()
		case 'F':
			v.openFilterDialog()
		case 'r':
			v.seriesFiles = map[int]seriesFiles{} // a manual reload also refreshes file properties
			v.reload()
		case 'i':
			v.open()
		case 's':
			v.search()
		case 't':
			v.toggleMonitored()
		default:
			return ev
		}
		return nil
	}
	return ev
}

// activate is called when the view becomes visible; it always refreshes so
// changes made elsewhere show up.
func (v *libraryView) activate() {
	v.app.app.SetFocus(v.pane().table)
	v.render()
	v.reload()
}

// reload fetches both lists in parallel.
func (v *libraryView) reload() {
	for _, p := range v.panes {
		v.reloadPane(p)
	}
}

func (v *libraryView) reloadPane(p *libPane) {
	p.gen++
	gen, kind := p.gen, p.kind
	go func() {
		ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
		defer cancel()
		var items []libItem
		var err error
		if kind == kindMovies {
			var movies []radarr.Movie
			if movies, err = v.radarr.Movies(ctx); err == nil {
				for _, m := range movies {
					it := newMovieItem(m)
					it.cover = coverFor(v.radarr.Client, m.Images, true)
					items = append(items, it)
				}
			}
		} else {
			var series []sonarr.Series
			if series, err = v.sonarr.Series(ctx); err == nil {
				for _, s := range series {
					it := newSeriesItem(s)
					it.cover = coverFor(v.sonarr.Client, s.Images, true)
					items = append(items, v.withCachedFiles(it))
				}
			}
		}
		v.app.post(func() {
			v.app.SetService(kind.service(), "", err)
			if gen != p.gen {
				return
			}
			p.err = err
			if err == nil && kind == kindSeries {
				defer v.loadSeriesFiles(false)
			}
			if err != nil {
				// Keep showing the last good list; say why it is stale.
				v.app.SetMessage("[red]" + kind.service() + ": " + tview.Escape(err.Error()))
			} else {
				p.all, p.loaded = items, true
			}
			v.render()
		})
	}()
}

func (v *libraryView) selected() (libItem, bool) {
	p := v.pane()
	r, _ := p.table.GetSelection()
	if r < 1 || r > len(p.shown) {
		return libItem{}, false
	}
	return p.shown[r-1], true
}

func (v *libraryView) render() {
	for _, p := range v.panes {
		v.renderPane(p)
	}
	v.header.SetText("[::b]Library[::-] · Tab switches list · each list has its own filters")
	v.renderDetails()
}

func (v *libraryView) renderPane(p *libPane) {
	selID := -1
	if r, _ := p.table.GetSelection(); r >= 1 && r <= len(p.shown) {
		selID = p.shown[r-1].id
	}
	p.shown = filterItems(p.all, p.filter, p.text, p.attr)

	p.table.Clear()
	header(p.table, 0, "Title", "Status", "Size")
	selRow := 0
	for i, it := range p.shown {
		p.table.SetCell(i+1, 0, tview.NewTableCell(monMark(it.monitored)+" "+it.label).SetExpansion(1))
		p.table.SetCell(i+1, 1, tview.NewTableCell(it.status))
		p.table.SetCell(i+1, 2, tview.NewTableCell(it.size).SetAlign(tview.AlignRight))
		if it.id == selID {
			selRow = i + 1
		}
	}
	placeholder := "Nothing matches the filter"
	switch {
	case p.err != nil && !p.loaded:
		placeholder = "Could not load, press r to retry"
	case !p.loaded:
		placeholder = "Loading…"
	case len(p.all) == 0:
		placeholder = "Empty"
	}
	restoreSelection(p.table, len(p.shown), selRow, placeholder)
	if selRow == 0 {
		p.table.ScrollToBeginning()
	}
	title := fmt.Sprintf(" %s %d/%d", p.kind, len(p.shown), len(p.all))
	if p.filter > 0 {
		title += " · [yellow]" + libFilters[p.filter].name + "[-]"
	}
	if p.attr.active() {
		title += " · [yellow]" + p.attr.String() + "[-]"
		if p.kind == kindSeries && v.filePending > 0 {
			title += fmt.Sprintf(" [gray](reading %d…)[-]", v.filePending)
		}
	}
	if p.err != nil && p.loaded {
		title += " [red](outdated)[-]"
	}
	p.table.SetTitle(title + " ")
}

func (v *libraryView) renderDetails() {
	if it, ok := v.selected(); ok {
		v.details.Show(it.details, it.cover)
		return
	}
	v.details.Clear()
}

// open starts the interactive search (movie) or the episode drill-down (series).
func (v *libraryView) open() {
	it, ok := v.selected()
	if !ok {
		return
	}
	if it.movie != nil {
		m := *it.movie
		v.app.openReleases("Releases for "+tview.Escape(movieTitleYear(m)),
			func(ctx context.Context) ([]arr.Release, error) { return v.radarr.Releases(ctx, m.ID) },
			v.radarr.Grab)
		return
	}
	v.app.openSeries(v.sonarr, *it.series, v.reload)
}

func (v *libraryView) search() {
	it, ok := v.selected()
	if !ok {
		return
	}
	if it.movie != nil {
		v.run("Searching for "+it.label, "Search started for "+it.label,
			func(ctx context.Context) error { return v.radarr.SearchMovie(ctx, it.id) }, nil)
		return
	}
	v.app.confirm("Search for all missing episodes of "+it.label+"?", func() {
		v.run("Searching for "+it.label, "Search started for "+it.label,
			func(ctx context.Context) error { return v.sonarr.SearchSeries(ctx, it.id) }, nil)
	})
}

func (v *libraryView) toggleMonitored() {
	it, ok := v.selected()
	if !ok {
		return
	}
	want := !it.monitored
	doing, done := "Monitoring ", "Monitored "
	if !want {
		doing, done = "Unmonitoring ", "Unmonitored "
	}
	v.run(doing+it.label, done+it.label, func(ctx context.Context) error {
		if it.movie != nil {
			return v.radarr.SetMonitored(ctx, it.id, want)
		}
		return v.sonarr.SetMonitored(ctx, it.id, want)
	}, v.reload)
}

// run executes fn off the UI goroutine, reports the outcome and then calls after.
func (v *libraryView) run(doing, done string, fn func(ctx context.Context) error, after func()) {
	v.app.SetMessage(doing + "…")
	go func() {
		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
		defer cancel()
		err := fn(ctx)
		v.app.post(func() {
			if err != nil {
				v.app.SetMessage("[red]" + tview.Escape(err.Error()))
				return
			}
			v.app.SetMessage("[green]" + done)
			if after != nil {
				after()
			}
		})
	}()
}

// openFilterDialog opens the property filter for the focused list. For series
// the files of all series are read so the dialog can leave out options that
// would match nothing.
func (v *libraryView) openFilterDialog() {
	p := v.pane()
	set := func(f attrFilter) {
		p.attr = f
		v.render()
		if p.kind == kindSeries {
			v.loadSeriesFiles(false)
		}
	}
	v.refreshDialog = v.app.openAttrFilter(p.attr, func() filterPool { return v.filterPool(p) }, set, func() { v.refreshDialog = nil })
	if p.kind == kindSeries {
		v.loadSeriesFiles(true)
	}
}

// filterPool lists the files of the items of one list that pass its status
// and text filters, for the filter dialog.
func (v *libraryView) filterPool(p *libPane) filterPool {
	var pool filterPool
	for _, it := range filterItems(p.all, p.filter, p.text, attrFilter{}) {
		if !it.attrsKnown {
			pool.unknown = true
		}
		pool.files = append(pool.files, it.attrs)
	}
	return pool
}

// withCachedFiles fills in the file properties of a series from the cache.
func (v *libraryView) withCachedFiles(it libItem) libItem {
	if it.attrsKnown || it.series == nil {
		return it
	}
	st := it.series.Statistics
	if c, ok := v.seriesFiles[it.id]; ok && c.count == st.EpisodeFileCount && c.size == st.SizeOnDisk {
		it.attrs, it.attrsKnown = c.attrs, true
	}
	return it
}

// loadSeriesFiles fetches the file properties of all series that lack them,
// but only while a property filter is active or the filter dialog is open
// (it costs one request per series).
func (v *libraryView) loadSeriesFiles(force bool) {
	if !force && !v.panes[kindSeries].attr.active() {
		return
	}
	p := v.panes[kindSeries]
	var todo []sonarr.Series
	for i, it := range p.all {
		p.all[i] = v.withCachedFiles(it)
		if !p.all[i].attrsKnown {
			todo = append(todo, *p.all[i].series)
		}
	}
	v.render()
	if len(todo) == 0 {
		return
	}
	v.fileGen++
	gen := v.fileGen
	v.filePending = len(todo)
	v.render()

	type fetched struct {
		s     sonarr.Series
		attrs []arr.FileAttrs
		err   error
	}
	jobs := make(chan sonarr.Series)
	results := make(chan fetched)
	const workers = 6
	for range workers {
		go func() {
			for s := range jobs {
				ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
				files, err := v.sonarr.EpisodeFiles(ctx, s.ID)
				cancel()
				f := fetched{s: s, err: err}
				for _, mf := range files {
					f.attrs = append(f.attrs, mf.Attrs())
				}
				results <- f
			}
		}()
	}
	go func() {
		for _, s := range todo {
			jobs <- s
		}
		close(jobs)
	}()
	go func() {
		for range todo {
			f := <-results
			v.app.post(func() {
				if gen != v.fileGen {
					return
				}
				v.filePending--
				if f.err != nil {
					v.app.SetService("Sonarr", "", f.err)
				} else {
					v.seriesFiles[f.s.ID] = seriesFiles{f.s.Statistics.EpisodeFileCount, f.s.Statistics.SizeOnDisk, f.attrs}
					for i, it := range p.all {
						if it.id == f.s.ID {
							p.all[i].attrs, p.all[i].attrsKnown = f.attrs, true
						}
					}
				}
				if v.filePending%10 == 0 { // keep redraws cheap for big libraries
					v.render()
					if v.refreshDialog != nil {
						v.refreshDialog()
					}
				}
			})
		}
	}()
}