package ui

import (
	"strconv"
	"strings"

	"git.yetaga.in/alazyreader/library/book"
	"github.com/gdamore/tcell"
)

type Drawable interface {
	Draw(tcell.Screen)
	SetSize(x, y, h, w int)
	SetStyle(tcell.Style)
}

type Offsets struct {
	Top     int
	Bottom  int
	Left    int
	Right   int
	Percent int
}

type Contents []struct {
	Offsets   Offsets
	Container Drawable
}

const (
	LayoutUnmanaged = iota
	LayoutHorizontalEven
	LayoutVerticalEven
	LayoutHorizontalPercent
	LayoutVerticalPercent
)

var (
	StyleActive   = tcell.Style(0).Foreground(tcell.ColorWhite).Background(tcell.ColorBlack)
	StyleInactive = tcell.Style(0).Foreground(tcell.ColorGray).Background(tcell.ColorBlack)
)

// A Container has no visible UI of its own, but arranges sub-components on the screen.
// layoutMethod manages how subcomponents are organized. If `LayoutUnmanaged`, it just uses the offsets
// in contents to paint on the screen. Otherwise, `LayoutHorizontalEven` and `LayoutVerticalEven` will
// have it compute even distributions of space for all components either horizontally or vertically,
// filling the container.
type Container struct {
	x, y         int
	h, w         int
	layoutMethod int
	contents     Contents
}

func NewContainer(contents Contents, layoutMethod int) *Container {
	return &Container{
		layoutMethod: layoutMethod,
		contents:     contents,
	}
}

func (c *Container) Draw(s tcell.Screen) {
	for i := range c.contents {
		c.contents[i].Container.Draw(s)
	}
}

func (c *Container) SetSize(x, y, h, w int) {
	c.x, c.y, c.h, c.w = x, y, h, w
	carry := 0
	if c.layoutMethod == LayoutVerticalEven {
		num := len(c.contents)
		extra := c.h % num
		for r := range c.contents {
			w := c.w
			h := c.h / num
			x := c.x
			y := c.y + (h * r) + carry
			if extra > 0 { // distribute "extra" space to containers as we have some left
				h++
				extra--
				carry++
			}
			c.contents[r].Container.SetSize(x, y, h, w)
		}
	} else if c.layoutMethod == LayoutHorizontalEven {
		num := len(c.contents)
		extra := c.w % num
		for r := range c.contents {
			w := c.w / num
			h := c.h
			x := c.x + (w * r) + carry
			y := c.y
			if extra > 0 { // distribute "extra" space to containers as we have some left
				w++
				extra--
				carry++
			}
			c.contents[r].Container.SetSize(x, y, h, w)
		}
	} else if c.layoutMethod == LayoutHorizontalPercent {
		// first, work out overall distribution
		total := 0
		for r := range c.contents {
			// `0` or negatives are set as minimum
			if c.contents[r].Offsets.Percent < 1 {
				total += 1
			} else {
				total += c.contents[r].Offsets.Percent
			}
		}
		carry := 0
		// push around containers
		for r := range c.contents {
			ratio := (float64(c.contents[r].Offsets.Percent) / float64(total))
			w := int(float64(c.w) * ratio)
			h := c.h
			x := c.x + carry
			y := c.y
			carry += w
			// and add any remaining space to the last container
			if r == len(c.contents)-1 {
				w += (c.w - carry)
			}
			c.contents[r].Container.SetSize(x, y, h, w)
		}
	} else if c.layoutMethod == LayoutVerticalPercent {
		// first, work out overall distribution
		total := 0
		for r := range c.contents {
			// `0` or negatives are set as minimum
			if c.contents[r].Offsets.Percent < 1 {
				total += 1
			} else {
				total += c.contents[r].Offsets.Percent
			}
		}
		carry := 0
		// push around containers
		for r := range c.contents {
			ratio := (float64(c.contents[r].Offsets.Percent) / float64(total))
			w := c.w
			h := int(float64(c.h) * ratio)
			x := c.x
			y := c.y + carry
			carry += h
			// and add any remaining space to the last container
			if r == len(c.contents)-1 {
				h += (c.h - carry)
			}
			c.contents[r].Container.SetSize(x, y, h, w)
		}
	} else {
		for r := range c.contents {
			x := c.x + c.contents[r].Offsets.Left
			y := c.y + c.contents[r].Offsets.Top
			h := c.h - c.contents[r].Offsets.Bottom
			w := c.w - c.contents[r].Offsets.Right
			c.contents[r].Container.SetSize(x, y, h, w)
		}
	}
}

func (c *Container) SetStyle(s tcell.Style) {
	// containers have no visible elements to style
}

func (c *Container) Contents() Contents {
	return c.contents
}

func (c *Container) SetContents(con Contents) {
	c.contents = con
}

// A Box draws a ASCII box around its contents, with an optional title and footer.
type Box struct {
	x, y      int
	h, w      int
	title     Drawable
	menuItems Drawable
	contents  Contents
	style     tcell.Style
	cascade   bool
}

func NewBox(title string, menuItems []string, contents Contents, initialStyle tcell.Style, cascade bool) *Box {
	return &Box{
		title:     NewPaddedText(title),
		menuItems: NewPaddedText(strings.Join(menuItems, " ")),
		contents:  contents,
		style:     initialStyle,
		cascade:   cascade,
	}
}

func (b *Box) SetSize(x, y, h, w int) {
	b.x, b.y, b.h, b.w = x, y, h, w
	b.title.SetSize(b.x+2, b.y, 0, 0)
	b.menuItems.SetSize(b.x+2, b.y+b.h-1, 0, 0)
	for c := range b.contents {
		x := b.x + b.contents[c].Offsets.Left
		y := b.y + b.contents[c].Offsets.Top
		h := b.h - b.contents[c].Offsets.Bottom
		w := b.w - b.contents[c].Offsets.Right
		b.contents[c].Container.SetSize(x, y, h, w)
	}
}

func (b *Box) Draw(s tcell.Screen) {
	for m := b.x + 1; m < b.x+b.w-1; m++ {
		s.SetContent(m, b.y, tcell.RuneHLine, nil, b.style)
		s.SetContent(m, b.y+b.h-1, tcell.RuneHLine, nil, b.style)
	}
	for m := b.y + 1; m < b.y+b.h-1; m++ {
		s.SetContent(b.x, m, tcell.RuneVLine, nil, b.style)
		s.SetContent(b.x+b.w-1, m, tcell.RuneVLine, nil, b.style)
	}
	s.SetContent(b.x, b.y, tcell.RuneULCorner, nil, b.style)
	s.SetContent(b.x+b.w-1, b.y, tcell.RuneURCorner, nil, b.style)
	s.SetContent(b.x, b.y+b.h-1, tcell.RuneLLCorner, nil, b.style)
	s.SetContent(b.x+b.w-1, b.y+b.h-1, tcell.RuneLRCorner, nil, b.style)

	if b.title != nil {
		b.title.Draw(s)
	}
	if b.menuItems != nil {
		b.menuItems.Draw(s)
	}
	for c := range b.contents {
		b.contents[c].Container.Draw(s)
	}
}

func (b *Box) SetStyle(s tcell.Style) {
	b.style = s
	b.title.SetStyle(s)
	b.menuItems.SetStyle(s)
	if b.cascade {
		for c := range b.contents {
			b.contents[c].Container.SetStyle(s)
		}
	}
}

func (b *Box) Contents() Contents {
	return b.contents
}

func (b *Box) SetContents(c Contents) {
	b.contents = c
}

// A List is a scrollable, pageable list with a selector token.
type List struct {
	x, y      int
	h, w      int
	selected  int
	listItems []ListKeyValue
	style     tcell.Style
}

type ListKeyValue struct {
	Key   int
	Value string
}

func NewList(listItems []ListKeyValue, initialSelected int) *List {
	return &List{
		listItems: listItems,
		selected:  initialSelected,
	}
}

func (l *List) SetSize(x, y, h, w int) {
	l.x, l.y, l.h, l.w = x, y, h, w
}

func (l *List) Draw(s tcell.Screen) {
	for i := range l.listItems {
		for j, r := range l.listItems[i].Value {
			s.SetContent(l.x+j, l.y+i, r, nil, l.style)
		}
		if i == l.selected {
			s.SetContent(l.x+len(l.listItems[i].Value)+1, l.y+i, '<', nil, l.style)
		}
	}
}

func (l *List) SetStyle(s tcell.Style) {
	l.style = s
}

func (l *List) Selected() int {
	return l.selected
}

func (l *List) SelectedID() int {
	if l.listItems == nil || len(l.listItems) == 0 {
		return 0
	}
	return l.listItems[l.selected].Key
}

func (l *List) SetSelected(i int) {
	l.selected = i
}

func (l *List) ListMembers() []ListKeyValue {
	return l.listItems
}

// BookDetails displays an editable list of book details
type BookDetails struct {
	x, y  int
	h, w  int
	book  *book.Book
	style tcell.Style
}

func NewBookDetails(b *book.Book) *BookDetails {
	return &BookDetails{
		book: b,
	}
}

func (l *BookDetails) SetBook(b *book.Book) {
	l.book = b
}

func (l *BookDetails) SetSize(x, y, h, w int) {
	l.x, l.y, l.h, l.w = x, y, h, w
}

func (l *BookDetails) Draw(s tcell.Screen) {
	if l.book == nil {
		return
	}
	items := []struct {
		label string
		value string
	}{
		{"Title", l.book.Title},
		{"Authors", strings.Join(l.book.Authors, ", ")},
		{"Sort Author", l.book.SortAuthor},
		{"ISBN-10", l.book.ISBN10},
		{"ISBN-13", l.book.ISBN13},
		{"Format", l.book.Format},
		{"Genre", l.book.Genre},
		{"Publisher", l.book.Publisher},
		{"Series", l.book.Series},
		{"Volume", l.book.Volume},
		{"Year", l.book.Year},
		{"Signed", strconv.FormatBool(l.book.Signed)},
		{"On Loan", l.book.OnLoan},
		{"Cover URL", l.book.CoverURL},
		{"Notes", l.book.Notes},
		{"Description", l.book.Description},
	}
	for i := range items {
		if i < l.h-2 {
			kv := NewKeyValue(items[i].label, ": ", items[i].value)
			kv.SetSize(l.x, l.y+i, 0, 0)
			kv.SetStyle(l.style)
			kv.Draw(s)
		}
	}
}

func (l *BookDetails) SetStyle(s tcell.Style) {
	l.style = s
}

// PaddedText outputs strings with a space on both sides.
// Useful for generating headings, footers, etc. Used by Box.
type PaddedText struct {
	x, y  int
	h, w  int
	text  string
	style tcell.Style
}

func NewPaddedText(text string) *PaddedText {
	return &PaddedText{text: text}
}

func (p *PaddedText) SetSize(x, y, _, _ int) {
	p.x, p.y, p.h, p.w = x, y, 1, len(p.text)+2
}

func (p *PaddedText) SetStyle(s tcell.Style) {
	p.style = s
}

func (p *PaddedText) Draw(s tcell.Screen) {
	if p.text == "" {
		return
	}
	t := p.x
	s.SetContent(t, p.y, ' ', nil, p.style)
	t++
	for _, r := range p.text {
		s.SetContent(t, p.y, r, nil, p.style)
		t++
	}
	s.SetContent(t, p.y, ' ', nil, p.style)
}

type KeyValue struct {
	x, y      int
	h, w      int
	key       string
	value     string
	separator string
	style     tcell.Style
}

func NewKeyValue(key, separator, value string) *KeyValue {
	return &KeyValue{
		key:       key,
		separator: separator,
		value:     value,
	}
}

func (p *KeyValue) SetSize(x, y, _, _ int) {
	p.x, p.y, p.h, p.w = x, y, 1, len(p.key)+len(p.separator)+len(p.value)
}

func (p *KeyValue) SetStyle(s tcell.Style) {
	p.style = s
}

func (p *KeyValue) Draw(s tcell.Screen) {
	for j, r := range p.key {
		s.SetContent(p.x+j, p.y, r, nil, p.style)
	}
	for j, r := range p.separator {
		s.SetContent(p.x+len(p.key)+j, p.y, r, nil, p.style)
	}
	for j, r := range p.value {
		s.SetContent(p.x+len(p.key)+len(p.separator)+j, p.y, r, nil, p.style)
	}
}

func (p *KeyValue) GetValue() string {
	return p.value
}