package buffer

import (
	"citrons.xyz/talk/tui"
)

type Buffer struct {
	id string
	top *bufList
	bottom *bufList
	scroll tui.ScrollState
	Closed bool
}

type Message interface {
	Id() string
	Show(odd bool)
}

type bufList struct {
	msg Message
	odd bool
	prev *bufList
	next *bufList
}

func New(id string) Buffer {
	return Buffer {id: id}
}

func (b *Buffer) Add(msg Message) {
	l := &bufList {msg: msg} 
	if b.bottom != nil {
		b.bottom.next = l
		l.prev = b.bottom
		l.odd = !b.bottom.odd
	}
	b.bottom = l
	if b.top == nil {
		b.top = b.bottom
	}
}

func (b *Buffer) AddTop(msg Message) {
	l := bufList {msg: msg} 
	if b.top != nil {
		b.top.prev = &l
		l.next = b.top
		l.odd = !b.bottom.odd
	}
	b.top = &l
	if b.bottom == nil {
		b.bottom = b.top
	}
}

func (b *Buffer) Scroll(amnt int) {
	b.scroll.Scroll(amnt)
}

func (b *Buffer) ScrollBottom() {
	b.scroll.ToStart()
}

func (b *Buffer) AtBottom() bool {
	return b.scroll.AtFirst()
}

func (b *Buffer) AtTop() bool {
	return b.scroll.AtLast()
}

func (b *Buffer) Show() (atTop bool) {
	tui.Push(b.id, tui.Box {
		Width: tui.Fill, Height: tui.Fill, Dir: tui.Up, Overflow: true,
		Scroll: &b.scroll,
	})
	defer tui.Pop()

	for m := b.bottom; m != nil; m = m.prev {
		var bg int32 = tui.Black
		if m.odd {
			bg = 236
		}
		tui.Push(m.msg.Id(), tui.Box {
			Width: tui.Fill, Height: tui.Children,
			Style: &tui.Style {Fg: tui.White, Bg: bg},
		})
		m.msg.Show(m.odd)
		tui.Pop()
	}

	return atTop
}