package ui

import (
	"slices"
	"strings"

	"github.com/rivo/tview"

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

// attrFilter narrows the library by properties of the downloaded files. An
// empty field means "any". All fields must match the same file; a series
// matches when any of its files does.
type attrFilter struct {
	res, codec, hdr, audio, lang string
}

const anyOption = "any"

var (
	resOptions   = []string{"2160p", "1080p", "720p", "SD"}
	codecOptions = []string{arr.CodecX265, arr.CodecX264, arr.CodecAV1}
	hdrOptions   = []string{"HDR", "DV", "SDR"}
	audioOptions = []string{arr.AudioAtmos, arr.AudioTrueHD, arr.AudioDTSX, arr.AudioDTSHD, arr.AudioDTS,
		arr.AudioDDPlus, arr.AudioDD, arr.AudioAAC, arr.AudioFLAC, arr.AudioOpus}
)

func (f attrFilter) active() bool { return f != attrFilter{} }

// String lists the active criteria for the header, e.g. "1080p x265 DV".
func (f attrFilter) String() string {
	var parts []string
	for _, p := range []string{f.res, f.codec, f.hdr, f.audio, f.lang} {
		if p != "" {
			parts = append(parts, p)
		}
	}
	return strings.Join(parts, " ")
}

func (f attrFilter) matchFile(a arr.FileAttrs) bool {
	switch f.res {
	case "":
	case "SD":
		if a.Resolution <= 0 || a.Resolution > 576 {
			return false
		}
	default:
		if f.res != itoa(a.Resolution)+"p" {
			return false
		}
	}
	if f.codec != "" && f.codec != a.Codec {
		return false
	}
	switch f.hdr {
	case "HDR":
		if !a.HDR {
			return false
		}
	case "DV":
		if !a.DV {
			return false
		}
	case "SDR":
		if a.HDR || a.DV {
			return false
		}
	}
	if f.audio != "" && !slices.Contains(a.Audio, f.audio) {
		return false
	}
	if f.lang != "" && !slices.ContainsFunc(a.Languages, func(l string) bool { return strings.EqualFold(l, f.lang) }) {
		return false
	}
	return true
}

// match reports whether any of the files matches. Without files nothing matches.
func (f attrFilter) match(files []arr.FileAttrs) bool {
	return slices.ContainsFunc(files, f.matchFile)
}

// filterPool is what the filter dialog works on: the files of every item that
// passes the other filters. It decides which dropdown entries are offered.
type filterPool struct {
	files   [][]arr.FileAttrs // one entry per item (a series has several files)
	unknown bool              // some files are not read yet: nothing can be ruled out
}

// has reports whether at least one item matches f.
func (p filterPool) has(f attrFilter) bool {
	return p.unknown || slices.ContainsFunc(p.files, f.match)
}

// languages lists the audio languages in the pool, sorted.
func (p filterPool) languages() []string {
	seen := map[string]bool{}
	var out []string
	for _, files := range p.files {
		for _, a := range files {
			for _, l := range a.Languages {
				if !seen[l] {
					seen[l] = true
					out = append(out, l)
				}
			}
		}
	}
	slices.Sort(out)
	return out
}

// facet is one dropdown of the filter dialog.
type facet struct {
	label      string
	candidates func(filterPool) []string
	get        func(attrFilter) string
	with       func(attrFilter, string) attrFilter

	dd     *tview.DropDown
	values []string // the listed options; values[0] is "" for "any"
}

func staticOptions(o []string) func(filterPool) []string {
	return func(filterPool) []string { return o }
}

var facetDefs = []facet{
	{"Quality", staticOptions(resOptions), func(f attrFilter) string { return f.res }, func(f attrFilter, v string) attrFilter { f.res = v; return f }, nil, nil},
	{"Language", filterPool.languages, func(f attrFilter) string { return f.lang }, func(f attrFilter, v string) attrFilter { f.lang = v; return f }, nil, nil},
	{"Codec", staticOptions(codecOptions), func(f attrFilter) string { return f.codec }, func(f attrFilter, v string) attrFilter { f.codec = v; return f }, nil, nil},
	{"HDR", staticOptions(hdrOptions), func(f attrFilter) string { return f.hdr }, func(f attrFilter, v string) attrFilter { f.hdr = v; return f }, nil, nil},
	{"Audio", staticOptions(audioOptions), func(f attrFilter) string { return f.audio }, func(f attrFilter, v string) attrFilter { f.audio = v; return f }, nil, nil},
}

// listedValues returns the options a facet offers: those that, together with
// the other chosen criteria, still leave at least one result, plus the
// current choice. The first entry is always "" (any).
func listedValues(f facet, state attrFilter, pool filterPool) []string {
	cur := f.get(state)
	vals := []string{""}
	cands := f.candidates(pool)
	if cur != "" && !slices.Contains(cands, cur) {
		cands = append([]string{cur}, cands...)
	}
	for _, o := range cands {
		if o == cur || pool.has(f.with(state, o)) {
			vals = append(vals, o)
		}
	}
	return vals
}

// openAttrFilter shows the dialog to pick quality, language, codec, HDR and
// audio (the most used first). Every change is passed to set immediately so the list behind the
// dialog follows along, also while moving through an open list; Cancel and Esc
// restore cur. Entries that would leave no results are not offered. The
// returned function re-evaluates them when the pool has changed; onClose runs
// when the dialog goes away.
func (a *App) openAttrFilter(cur attrFilter, pool func() filterPool, set func(attrFilter), onClose func()) (refresh func()) {
	orig, state := cur, cur
	facets := make([]*facet, len(facetDefs))
	form := tview.NewForm()
	byDropDown := map[*tview.DropDown]*facet{}
	for i := range facetDefs {
		f := facetDefs[i]
		facets[i] = &f
		form.AddDropDown(f.label, []string{anyOption}, 0, nil)
		f.dd = form.GetFormItem(i).(*tview.DropDown)
		f.values = []string{""}
		byDropDown[f.dd] = facets[i]
		facets[i].dd = f.dd
	}

	rebuilding := false
	var onSelect func(f *facet) func(string, int)
	refresh = func() {
		p := pool()
		rebuilding = true
		defer func() { rebuilding = false }()
		for _, f := range facets {
			if f.dd.IsOpen() {
				continue // do not pull the list from under the user
			}
			vals := listedValues(*f, state, p)
			if slices.Equal(vals, f.values) {
				continue
			}
			f.values = vals
			f.dd.SetOptions(append([]string{anyOption}, vals[1:]...), onSelect(f))
			f.dd.SetCurrentOption(slices.Index(vals, f.get(state)))
		}
	}
	onSelect = func(f *facet) func(string, int) {
		return func(_ string, index int) {
			if rebuilding || index < 0 || index >= len(f.values) {
				return
			}
			state = f.with(state, f.values[index])
			set(state)
			refresh()
		}
	}
	for _, f := range facets {
		f.dd.SetSelectedFunc(onSelect(f))
	}
	refresh()

	cancel := func() {
		a.closeModal()
		set(orig)
	}
	form.AddButton("Apply", a.closeModal)
	form.AddButton("Reset", func() {
		a.closeModal()
		set(attrFilter{})
	})
	form.AddButton("Cancel", cancel)
	arrowNavigation(form, cancel, &browseHooks{
		browse: func(dd *tview.DropDown, index int) {
			if f := byDropDown[dd]; f != nil && index >= 0 && index < len(f.values) {
				set(f.with(state, f.values[index]))
			}
		},
		abort: func() { set(state) }, // list closed without choosing: back to the committed value
	})
	form.SetBorder(true).SetTitle(" Filter by properties ")
	a.openSidePanel(form, 40, 17, "↑↓ move · ←→ change (applies live) · Enter apply · Esc cancel", onClose)
	return refresh
}