package ui

import (
	"image"

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

const (
	minCoverRows = 6  // a smaller poster is not worth showing
	minCoverCols = 8  //
	minTextRows  = 10 // the poster never takes these rows from the text
)

// detailPane shows the details of one title: the head (title and facts) with
// the poster to its right on top, and the plot below both. On panes too small
// for the poster everything is one text.
type detailPane struct {
	*tview.Flex // column: top row, plot
	app         *App
	top         *tview.Flex // row: head, cover
	head        *tview.TextView
	cover       *coverView
	plot        *tview.TextView

	text     detailText
	want     string // key of the poster that should be shown
	hasCover bool   // a poster (or its loading note) is part of the content
	combined bool   // head and plot are shown together in the plot view
}

func newDetailPane(app *App) *detailPane {
	d := &detailPane{
		Flex:  tview.NewFlex().SetDirection(tview.FlexRow),
		app:   app,
		top:   tview.NewFlex(),
		head:  tview.NewTextView().SetDynamicColors(true).SetWordWrap(true),
		cover: newCoverView(app.coverStyle),
		plot:  tview.NewTextView().SetDynamicColors(true).SetWordWrap(true),
	}
	d.cover.SetBorderPadding(0, 0, 1, 0)
	d.top.AddItem(d.head, 0, 1, false).AddItem(d.cover, 0, 0, false)
	d.AddItem(d.top, 0, 0, false).AddItem(d.plot, 0, 1, false)
	d.SetBorder(true).SetTitle(" Details ")
	d.combined = true
	return d
}

// Show displays the text and, if there is one, the poster.
func (d *detailPane) Show(text detailText, ref coverRef) {
	d.text = text
	d.applyText()
	if !d.app.covers || ref.fetch == nil {
		d.want, d.hasCover = "", false
		d.cover.setImage(nil)
		return
	}
	d.want, d.hasCover = ref.key, true
	d.cover.setNote("loading cover…")
	want := ref.key
	d.app.loadCover(ref, func(img *image.RGBA, err error) {
		if d.want != want {
			return // the selection moved on
		}
		if err != nil {
			d.hasCover = false // nothing to show: give the room back to the text
			d.cover.setImage(nil)
			return
		}
		d.cover.setImage(img)
	})
}

// Clear empties the pane.
func (d *detailPane) Clear() { d.Show(detailText{}, coverRef{}) }

// applyText puts the texts into their views for the current layout.
func (d *detailPane) applyText() {
	if d.combined {
		d.head.SetText("")
		d.plot.SetText(d.text.String()).ScrollToBeginning()
		return
	}
	d.head.SetText(d.text.head).ScrollToBeginning()
	d.plot.SetText(d.text.plot).ScrollToBeginning()
}

func (d *detailPane) Draw(screen tcell.Screen) {
	_, _, w, h := d.GetInnerRect()
	coverW, coverH := 0, 0
	if d.hasCover {
		aw, ah := d.cover.aspect()
		// At most 40% of the width, and the plot keeps its rows.
		coverW, coverH = coverCells(aw, ah, w*2/5, h-minTextRows)
		if coverH < minCoverRows || coverW < minCoverCols {
			coverW, coverH = 0, 0
		}
	}
	if combined := coverW == 0; combined != d.combined {
		d.combined = combined
		d.applyText()
	}
	d.ResizeItem(d.top, coverH, 0)
	d.top.ResizeItem(d.cover, coverW+1, 0) // +1: the padding left of the poster
	d.Flex.Draw(screen)
}