package ui

import (
	"image"

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

const (
	coverRows    = 20 // poster height in terminal rows
	minCoverRows = 6  // a smaller poster is not worth showing
	minTextRows  = 10 // the poster never takes these rows from the text
)

// detailPane shows a poster above a text. The poster shrinks on short panes
// and is dropped when the text would get too little room.
type detailPane struct {
	*tview.Flex
	app   *App
	cover *coverView
	text  *tview.TextView

	want      string // key of the poster that should be shown
	hasCover  bool   // a poster (or its loading note) is part of the content
	coverSize int    // rows currently given to the poster
}

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

// Show displays the text and, if there is one, the poster.
func (d *detailPane) Show(text string, ref coverRef) {
	d.text.SetText(text).ScrollToBeginning()
	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("", coverRef{}) }

func (d *detailPane) Draw(screen tcell.Screen) {
	_, _, _, h := d.GetInnerRect()
	rows := 0
	if d.hasCover {
		rows = min(coverRows, h-minTextRows)
		if rows < minCoverRows {
			rows = 0
		}
	}
	if rows != d.coverSize {
		d.coverSize = rows
		d.ResizeItem(d.cover, rows, 0)
	}
	d.Flex.Draw(screen)
}