package ui

import (
	"cmp"
	"context"
	"fmt"
	"slices"
	"strings"
	"time"

	"github.com/gdamore/tcell/v2"
	"github.com/rivo/tview"

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

// Sort modes of the release list; sortLabels[i] names mode i.
const (
	sortBest = iota
	sortSize
	sortAge
	numSortModes
)

var sortLabels = [numSortModes]string{"best", "size", "age"}

// releasesView is the full-screen interactive search result list.
type releasesView struct {
	app   *App
	title string
	grab  func(ctx context.Context, r arr.Release) error

	root   *tview.Flex
	header *tview.TextView
	table  *tview.Table
	detail *tview.TextView
	cancel context.CancelFunc // aborts the running indexer search

	all          []arr.Release // usenet releases only
	shown        []arr.Release
	torrents     int  // torrent releases left out
	searched     bool // the indexer search has finished
	sortMode     int
	hideRejected bool
}

// openReleases starts an interactive search and shows the results as they arrive.
func (a *App) openReleases(title string, fetch func(context.Context) ([]arr.Release, error), grab func(context.Context, arr.Release) error) {
	v := &releasesView{
		app:    a,
		title:  title,
		grab:   grab,
		header: tview.NewTextView().SetDynamicColors(true),
		table:  tview.NewTable().SetSelectable(true, false).SetFixed(1, 0),
		detail: tview.NewTextView().SetDynamicColors(true).SetWordWrap(true),
	}
	v.table.SetBorder(true)
	v.root = tview.NewFlex().SetDirection(tview.FlexRow).
		AddItem(v.header, 1, 0, false).
		AddItem(v.table, 0, 1, true).
		AddItem(v.detail, 3, 0, false)

	v.table.SetSelectionChangedFunc(func(int, int) { v.renderDetail() })
	v.table.SetSelectedFunc(func(int, int) { v.grabSelected() })
	v.table.SetInputCapture(func(ev *tcell.EventKey) *tcell.EventKey {
		switch {
		case ev.Key() == tcell.KeyEscape:
			v.close()
		case ev.Key() == tcell.KeyRune && ev.Rune() == 'g':
			v.grabSelected()
		case ev.Key() == tcell.KeyRune && ev.Rune() == 's':
			v.sortMode = (v.sortMode + 1) % numSortModes
			v.render()
		case ev.Key() == tcell.KeyRune && ev.Rune() == 'f':
			v.hideRejected = !v.hideRejected
			v.render()
		default:
			return ev
		}
		return nil
	})

	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
	v.cancel = cancel
	v.render() // shows the "searching" placeholder
	a.openFull(v.root, "Enter/g grab · s sort · f hide rejected · Esc back")

	go func() {
		releases, err := fetch(ctx)
		if ctx.Err() == context.Canceled {
			return
		}
		a.post(func() {
			if err != nil {
				v.header.SetText("[red]Search failed: " + tview.Escape(err.Error()))
				v.table.Clear()
				return
			}
			v.setReleases(releases)
		})
	}()
}

func (v *releasesView) close() {
	v.cancel()
	v.app.closeModal()
}

func (v *releasesView) setReleases(releases []arr.Release) {
	v.all, v.torrents = nil, 0
	for _, r := range releases {
		// Downloads go to SABnzbd, which can only handle Usenet.
		if r.Protocol == "torrent" {
			v.torrents++
			continue
		}
		v.all = append(v.all, r)
	}
	v.searched = true
	v.render()
}

// render rebuilds the table, keeping the selected release selected.
func (v *releasesView) render() {
	selGUID := ""
	if r, ok := v.selected(); ok {
		selGUID = r.GUID
	}
	v.shown = visibleReleases(v.all, v.hideRejected, v.sortMode)

	v.table.Clear()
	for i, c := range []string{"", "Title", "Quality", "Size", "Age", "Indexer", "Score"} {
		cell := tview.NewTableCell(c).SetTextColor(tcell.ColorYellow).SetSelectable(false)
		if c == "Title" {
			cell.SetExpansion(1)
		}
		v.table.SetCell(0, i, cell)
	}
	selRow := 0
	for i, r := range v.shown {
		cells := []string{
			releaseMark(r), tview.Escape(r.Title), tview.Escape(r.QualityName()), formatSize(r.Size),
			formatReleaseAge(r.AgeMinutes), tview.Escape(r.Indexer), fmt.Sprint(r.CustomFormatScore),
		}
		for c, text := range cells {
			cell := tview.NewTableCell(text)
			if c == 1 {
				cell.SetExpansion(1)
			}
			v.table.SetCell(i+1, c, cell)
		}
		if r.GUID == selGUID {
			selRow = i + 1
		}
	}
	switch {
	case !v.searched:
		v.table.SetCell(1, 1, tview.NewTableCell("[gray]Searching indexers… (Esc to cancel)").SetSelectable(false))
	case len(v.shown) == 0:
		msg := "No releases found. Are indexers configured?"
		if len(v.all) > 0 {
			msg = "All releases are hidden by the filter (f)"
		}
		v.table.SetCell(1, 1, tview.NewTableCell("[gray]"+msg).SetSelectable(false))
	}
	// With no selectable row tview's Down/Up handling never terminates.
	v.table.SetSelectable(len(v.shown) > 0, false)
	if len(v.shown) > 0 {
		v.table.Select(max(selRow, 1), 0)
		if selRow <= 1 {
			// Otherwise the table can keep a stale scroll offset from the
			// "searching" placeholder and show the middle of the list.
			v.table.ScrollToBeginning()
		}
	} else {
		v.table.Select(0, 0)
	}
	v.renderHeader()
	v.renderDetail()
}

func (v *releasesView) renderHeader() {
	s := "[::b]" + v.title + "[::-]" // callers escape the title
	if v.searched {
		s += fmt.Sprintf(" · %d of %d releases", len(v.shown), len(v.all))
	}
	s += " · sort: " + sortLabels[v.sortMode]
	if v.hideRejected {
		s += " · [yellow]rejected hidden[-]"
	}
	if v.torrents > 0 {
		s += fmt.Sprintf(" · [gray]%d torrent release%s hidden[-]", v.torrents, plural(v.torrents))
	}
	v.header.SetText(s)
}

func (v *releasesView) renderDetail() {
	r, ok := v.selected()
	if !ok {
		v.detail.SetText("")
		return
	}
	var lines []string
	switch {
	case len(r.Rejections) > 0:
		lines = append(lines, "[red]Rejected:[-] "+tview.Escape(strings.Join(r.Rejections, "; ")))
	case r.Approved:
		lines = append(lines, "[green]Approved[-]")
	}
	var facts []string
	if r.ReleaseGroup != "" {
		facts = append(facts, "group "+tview.Escape(r.ReleaseGroup))
	}
	if l := r.LanguageNames(); l != "" {
		facts = append(facts, tview.Escape(l))
	}
	if len(facts) > 0 {
		lines = append(lines, "[gray]"+strings.Join(facts, " · ")+"[-]")
	}
	v.detail.SetText(strings.Join(lines, "\n"))
}

func (v *releasesView) selected() (arr.Release, bool) {
	row, _ := v.table.GetSelection()
	if row < 1 || row > len(v.shown) {
		return arr.Release{}, false
	}
	return v.shown[row-1], true
}

// grabSelected sends the selected release to the download client; rejected
// releases need an explicit confirmation first.
func (v *releasesView) grabSelected() {
	r, ok := v.selected()
	if !ok {
		return
	}
	if len(r.Rejections) == 0 && !r.Rejected {
		v.doGrab(r)
		return
	}
	reasons := r.Rejections
	extra := ""
	if len(reasons) > 3 {
		extra = fmt.Sprintf("\n+%d more", len(reasons)-3)
		reasons = reasons[:3]
	}
	v.app.confirm("This release was rejected:\n"+tview.Escape(strings.Join(reasons, "\n"))+extra+"\n\nGrab it anyway?",
		func() { v.doGrab(r) })
}

func (v *releasesView) doGrab(r arr.Release) {
	v.app.SetMessage("Grabbing " + tview.Escape(truncate(r.Title, 60)) + "…")
	go func() {
		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
		defer cancel()
		err := v.grab(ctx, r)
		v.app.post(func() {
			if err != nil {
				v.app.SetMessage("[red]Grab failed: " + tview.Escape(err.Error()))
				return
			}
			v.app.SetMessage("[green]Sent to the download client: " + tview.Escape(truncate(r.Title, 60)))
		})
	}()
}

// visibleReleases applies the filter and sort order, returning a new slice.
func visibleReleases(all []arr.Release, hideRejected bool, mode int) []arr.Release {
	out := make([]arr.Release, 0, len(all))
	for _, r := range all {
		if hideRejected && isRejected(r) {
			continue
		}
		out = append(out, r)
	}
	slices.SortStableFunc(out, func(a, b arr.Release) int {
		switch mode {
		case sortSize:
			return cmp.Compare(b.Size, a.Size)
		case sortAge:
			return cmp.Compare(a.AgeMinutes, b.AgeMinutes)
		}
		// best: approved first, then format score, quality, and newest
		return cmp.Or(
			cmp.Compare(boolInt(isRejected(a)), boolInt(isRejected(b))),
			cmp.Compare(b.CustomFormatScore, a.CustomFormatScore),
			cmp.Compare(b.QualityWeight, a.QualityWeight),
			cmp.Compare(a.AgeMinutes, b.AgeMinutes),
		)
	})
	return out
}

func isRejected(r arr.Release) bool { return r.Rejected || len(r.Rejections) > 0 }

func boolInt(b bool) int {
	if b {
		return 1
	}
	return 0
}

// releaseMark is the status glyph in the first column.
func releaseMark(r arr.Release) string {
	switch {
	case !isRejected(r):
		return "[green]✓[-]"
	case r.TemporarilyRejected:
		return "[yellow]~[-]"
	}
	return "[red]✗[-]"
}

// formatSize renders a byte count as "1.4 GB".
func formatSize(b int64) string {
	const k = 1024.0
	f := float64(b)
	switch {
	case f >= k*k*k:
		return fmt.Sprintf("%.1f GB", f/(k*k*k))
	case f >= k*k:
		return fmt.Sprintf("%.0f MB", f/(k*k))
	case f > 0:
		return fmt.Sprintf("%.0f KB", f/k)
	}
	return "-"
}

// formatReleaseAge renders an age given in minutes as "45m", "5h" or "3d".
func formatReleaseAge(minutes float64) string {
	switch {
	case minutes < 60:
		return fmt.Sprintf("%dm", int(minutes))
	case minutes < 48*60:
		return fmt.Sprintf("%dh", int(minutes/60))
	}
	return fmt.Sprintf("%dd", int(minutes/(24*60)))
}