package client

import (
	"errors"
	"fmt"
	"math"

	"hackerbots.us/server"

	"github.com/nsf/termbox-go"
)

const d = 'v'
const u = '^'
const r = '>'
const l = '<'

// NewSpectator initializes and returns a *Spectator.
func NewSpectator(w, h float64) *Spectator {
	return &Spectator{
		StateStream: make(chan *server.Boardstate),
		Die:         make(chan struct{}),
		width:       w,
		height:      h,
	}
}

// Spectator encodes a termbox ui.
type Spectator struct {
	// max dimensions of field
	width, height float64

	// dimensions of the terminal window
	viewX, viewY int

	StateStream chan *server.Boardstate

	// when closed will cause the Spectator to exit the render loop.
	Die chan struct{}

	// User, if populated, will return a stream of (ostensibly keyboard) events
	// for use outside of the Spectator.
	User chan termbox.Event
}

// SetIDs is implemented so Spectator can be used as a client.Player.
func (s Spectator) SetIDs(map[string]string) {}

// GetStats is implemented so Spectator can be used as a client.Player.
func (s Spectator) GetStats() map[string]server.StatsRequest { return nil }

// Update is implemented so Spectator can be used as a client.Player.
func (s Spectator) Update(bs *server.Boardstate) map[string]server.Instruction {
	s.StateStream <- bs
	return nil
}

// Spectate runs the termbox render loop.
func (s *Spectator) Spectate() error {
	err := termbox.Init()
	if err != nil {
		return err
	}

	termbox.SetInputMode(termbox.InputMouse)

	s.viewX, s.viewY = termbox.Size()

	events := make(chan termbox.Event, 1024)
	go func() {
		for {
			events <- termbox.PollEvent()
		}
	}()

	termbox.HideCursor()
	termbox.Clear(termbox.ColorBlack, termbox.ColorBlack)

	func() {
		for {
			select {
			case event := <-events:
				switch event.Type {
				case termbox.EventKey:
					switch event.Key {
					case termbox.KeyCtrlZ, termbox.KeyCtrlC:
						return
					}

					switch event.Ch {
					case 'q':
						return
					case 'f':
						termbox.SetCell(
							20,
							20,
							'*',
							termbox.ColorRed, termbox.ColorBlack,
						)
					case 'c':
						termbox.Clear(termbox.ColorBlack, termbox.ColorBlack)
					}

				case termbox.EventResize:
					s.viewX, s.viewY = event.Width, event.Height
				case termbox.EventError:
					err = fmt.Errorf("Quitting because of termbox error:\n%v\n", event.Err)
					return
				}

				if s.User != nil {
					s.User <- event
				}
			case update := <-s.StateStream:
				termbox.Clear(termbox.ColorBlack, termbox.ColorBlack)

				for _, obstacle := range update.Obstacles {
					startX := int((obstacle.Bounds.A.X / s.width) * float64(s.viewX))
					stopX := int((obstacle.Bounds.B.X / s.width) * float64(s.viewX))
					startY := int((obstacle.Bounds.A.Y / s.height) * float64(s.viewY))
					stopY := int((obstacle.Bounds.B.Y / s.height) * float64(s.viewY))
					for x := startX; x < stopX; x++ {
						for y := startY; y < stopY; y++ {
							termbox.SetCell(
								x,
								s.viewY-y,
								' ',
								termbox.ColorBlack, termbox.ColorBlue,
							)
						}
					}
				}

				for _, bot := range update.OtherRobots {
					x := int((bot.Position.X / s.width) * float64(s.viewX))
					y := int((bot.Position.Y / s.height) * float64(s.viewY))
					var b rune
					if math.Abs(bot.Heading.X) > math.Abs(bot.Heading.Y) {
						if bot.Heading.X > 0 {
							b = r
						} else {
							b = l
						}
					} else {
						if bot.Heading.Y > 0 {
							b = u
						} else {
							b = d
						}
					}
					c := termbox.ColorRed
					if bot.Health <= 0 {
						c = termbox.ColorBlack
					}
					termbox.SetCell(
						x,
						s.viewY-y,
						b,
						c, termbox.ColorBlack,
					)
				}

				for _, p := range update.Projectiles {
					x := int((p.Position.X / s.width) * float64(s.viewX))
					y := int((p.Position.Y / s.height) * float64(s.viewY))
					termbox.SetCell(
						x,
						s.viewY-y,
						'·',
						termbox.ColorWhite|termbox.AttrBold, termbox.ColorBlack,
					)
				}

				for _, splosion := range update.Splosions {
					startX := int(((splosion.Position.X - float64(splosion.Radius)) / s.width) * float64(s.viewX))
					startY := int(((splosion.Position.Y - float64(splosion.Radius)) / s.height) * float64(s.viewY))
					stopX := int(((splosion.Position.X+float64(splosion.Radius))/s.width)*float64(s.viewX)) + 1
					stopY := int(((splosion.Position.Y+float64(splosion.Radius))/s.height)*float64(s.viewY)) + 1
					for x := startX; x < stopX; x++ {
						for y := startY; y < stopY; y++ {
							realX := float64(x) * s.width / float64(s.viewX)
							realY := float64(y) * s.height / float64(s.viewY)
							dX := realX - splosion.Position.X
							dY := realY - splosion.Position.Y
							curRad := math.Sqrt(dX*dX + dY*dY)
							if curRad < float64(splosion.Radius) {
								termbox.SetCell(
									x,
									s.viewY-y,
									'·',
									termbox.ColorYellow|termbox.AttrBold, termbox.ColorRed,
								)
							}
						}
					}
				}

				for _, bot := range update.MyRobots {
					x := int((bot.Position.X / s.width) * float64(s.viewX))
					y := int((bot.Position.Y / s.height) * float64(s.viewY))
					var b rune
					if math.Abs(bot.Heading.X) > math.Abs(bot.Heading.Y) {
						if bot.Heading.X > 0 {
							b = r
						} else {
							b = l
						}
					} else {
						if bot.Heading.Y > 0 {
							b = u
						} else {
							b = d
						}
					}
					c := termbox.ColorWhite
					if bot.Health <= 0 {
						c = termbox.ColorBlack
					}
					termbox.SetCell(
						x,
						s.viewY-y,
						b,
						c|termbox.AttrBold, termbox.ColorBlack,
					)
				}

				err = termbox.Flush()
			case <-s.Die:
				err = errors.New("was told to die")
				return
			}
		}
	}()

	termbox.Close()
	return err
}