package gel

import (
	"image"

	"github.com/p9c/p9/pkg/gel/gio/font"
	l "github.com/p9c/p9/pkg/gel/gio/layout"
	"github.com/p9c/p9/pkg/gel/gio/op"
	"github.com/p9c/p9/pkg/gel/gio/op/clip"
	"github.com/p9c/p9/pkg/gel/gio/text"
	"github.com/p9c/p9/pkg/gel/gio/unit"

	"golang.org/x/image/math/fixed"
)

// Text is a widget for laying out and drawing text.
type Text struct {
	*Window
	// alignment specify the text alignment.
	alignment text.Alignment
	// maxLines limits the number of lines. Zero means no limit.
	maxLines int
}

func (w *Window) Text() *Text {
	return &Text{Window: w}
}

// Alignment sets the alignment for the text
func (t *Text) Alignment(alignment text.Alignment) *Text {
	t.alignment = alignment
	return t
}

// MaxLines sets the alignment for the text
func (t *Text) MaxLines(maxLines int) *Text {
	t.maxLines = maxLines
	return t
}

func (t *Text) Fn(gtx l.Context, s *text.Shaper, fnt font.Font, size unit.Sp, txt string) l.Dimensions {
	cs := gtx.Constraints
	textSize := fixed.I(gtx.Sp(size))

	s.LayoutString(text.Parameters{
		Font:      fnt,
		PxPerEm:   textSize,
		MaxLines:  t.maxLines,
		Alignment: t.alignment,
		MaxWidth:  cs.Max.X,
		MinWidth:  cs.Min.X,
		Locale:    gtx.Locale,
	}, txt)

	m := op.Record(gtx.Ops)
	viewport := image.Rectangle{Max: cs.Max}
	it := GlyphIterator{
		Viewport: viewport,
		MaxLines: t.maxLines,
	}
	var glyphs [32]text.Glyph
	line := glyphs[:0]
	for g, ok := s.NextGlyph(); ok; g, ok = s.NextGlyph() {
		var ok bool
		if line, ok = it.PaintGlyph(gtx, s, g, line); !ok {
			break
		}
	}
	call := m.Stop()
	viewport.Min = viewport.Min.Add(it.Padding.Min)
	viewport.Max = viewport.Max.Add(it.Padding.Max)
	clipStack := clip.Rect(viewport).Push(gtx.Ops)
	call.Add(gtx.Ops)
	dims := l.Dimensions{Size: it.Bounds.Size()}
	dims.Size = cs.Constrain(dims.Size)
	dims.Baseline = dims.Size.Y - it.Baseline
	clipStack.Pop()
	return dims
}