package main

import (
	"fmt"
	"math"
	"math/rand"
	"time"

	"gogs.bullercodeworks.com/brian/termbox-util"

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

const (
	modeInit = iota
	modeRun
	modeRunInput
	modePause
	modeGameOver
)

type mainScreen struct {
	GameMode   int
	PlayerTurn int
	Player1    *player
	Player2    *player
	Bullet     *projectile
	Buildings  []building
	PauseMenu  *termboxUtil.Menu
	r          *rand.Rand
	animating  bool
	gravity    float64
}

func (screen *mainScreen) handleKeyPress(event termbox.Event) int {
	if event.Key == termbox.KeyEsc {
		if screen.GameMode != modePause {
			screen.GameMode = modePause
		} else {
			screen.GameMode = modeRun
		}
	}
	if screen.GameMode == modePause || screen.GameMode == modeGameOver {
		screen.PauseMenu.HandleKeyPress(event)
		if screen.PauseMenu.IsDone() {
			selOpt := screen.PauseMenu.GetSelectedOption()
			if selOpt.GetText() == "Exit" {
				return exitScreenIndex
			} else if selOpt.GetText() == "Resume" {
				screen.GameMode = modeRun
			} else if selOpt.GetText() == "Restart" {
				screen.GameMode = modeInit
				return titleScreenIndex
			}
		}
	}
	if screen.GameMode == modeRunInput {
		p := screen.Player1
		if screen.PlayerTurn == 2 {
			p = screen.Player2
		}
		if event.Key == termbox.KeySpace {
			screen.Bullet.init(p)
			screen.animating = true
			screen.GameMode = modeRun
		} else if event.Key == termbox.KeyArrowLeft || event.Ch == 'a' {
			p.projAngle--
		} else if event.Key == termbox.KeyArrowRight || event.Ch == 'd' {
			p.projAngle++
		} else if event.Key == termbox.KeyArrowUp || event.Ch == 'w' {
			p.projSpeed++
		} else if event.Key == termbox.KeyArrowDown || event.Ch == 's' {
			p.projSpeed--
		}
	}
	return mainScreenIndex
}

func (screen *mainScreen) performLayout(style style) {
	var bldCity int
	if screen.GameMode == modeInit {
		// Default screen gravity:
		screen.gravity = float64(-9.81)
		b := projectile{gravity: screen.gravity}
		screen.Bullet = &b
		// TODO: Reset Buildings
		screen.Buildings = []building{}
		// Create a random seed (from time)
		seed := fmt.Sprintf("%d", time.Now().UnixNano())
		screen.r = rand.New(rand.NewSource(getSeedFromString(seed + "-world")))
		screen.PlayerTurn = (screen.r.Int() % 2) + 1
		for bldCity < ScreenWidth {
			w := screen.r.Intn(8) + 6
			h := screen.r.Intn(ScreenHeight-10) + 2
			var c termbox.Attribute
			switch screen.r.Intn(3) {
			case 0:
				c = termbox.ColorRed
			case 1:
				c = termbox.ColorGreen
			case 2:
				c = termbox.ColorBlue
			}
			if ScreenWidth-(bldCity+w) < 5 {
				w += ScreenWidth - (bldCity + w)
			}
			b := building{startX: bldCity, width: w, height: h, color: c}
			screen.Buildings = append(screen.Buildings, b)
			bldCity += w
		}
		// Player 1 should be on the first 1/3 of the buildings
		bld := screen.r.Intn(len(screen.Buildings) / 3)
		p1x, p1y := screen.getRndPosForBuilding(bld)
		screen.Player1 = createPlayer(p1x, p1y)
		screen.Player1.gravity = screen.gravity

		// Player 2 should be on the third 1/3 of the buildings
		bld = screen.r.Intn(len(screen.Buildings)/3) + ((len(screen.Buildings) * 2) / 3)
		p2x, p2y := screen.getRndPosForBuilding(bld)
		if ScreenWidth-p2x < 5 {
			p2x, p2y = screen.getRndPosForBuilding(bld - 1)
		}
		screen.Player2 = createPlayer(p2x, p2y)
		screen.Player2.projAngle = 225
		screen.Player2.gravity = screen.gravity

		screen.PauseMenu = termboxUtil.CreateMenu("** GOPHER BATTLE **",
			[]string{"Resume", "Restart", "Exit"},
			(ScreenWidth/2)-11, (ScreenHeight/2)-3, 22, 6,
			style.defaultFg, style.defaultBg)
		screen.PauseMenu.SetBordered(true)
		screen.PauseMenu.EnableVimMode()
		screen.GameMode = modeRun
	}
}

func createPlayer(px, py int) *player {
	p := player{
		x:         px,
		y:         py,
		projSpeed: 10,
		projAngle: 315,
		baseColor: termbox.ColorCyan,
	}
	return &p
}

// Trigger all updates
func (screen *mainScreen) update() {
	if screen.GameMode == modeRun {
		if !screen.animating {
			if screen.PlayerTurn == 1 {
				screen.PlayerTurn = 2
				screen.Player1.turn = false
				screen.Player2.turn = true
			} else {
				screen.PlayerTurn = 1
				screen.Player1.turn = true
				screen.Player2.turn = false
			}
			screen.GameMode = modeRunInput
		} else {
			if screen.Bullet.x > 0 && screen.Bullet.x < ScreenWidth && screen.Bullet.y < ScreenHeight && screen.Bullet.y > -5000 {
				screen.Bullet.update()
				// Check for collisions
				if screen.Player1.didCollide(screen.Bullet) {
					screen.Player1.dead = true
					screen.PauseMenu.SetOptionDisabled(0)
					if screen.PlayerTurn == 1 {
						// Self kill
						screen.PauseMenu.SetTitle("Player 1 LOSES.")
					} else {
						// Victory!
						screen.PauseMenu.SetTitle("Player 2 Wins!")
					}
					screen.GameMode = modePause
				}
				if screen.Player2.didCollide(screen.Bullet) {
					screen.Player2.dead = true
					screen.PauseMenu.SetOptionDisabled(0)
					if screen.PlayerTurn == 2 {
						// Self kill
						screen.PauseMenu.SetTitle("Player 2 LOSES.")
					} else {
						// Victory!
						screen.PauseMenu.SetTitle("Player 1 Wins!")
					}
					screen.GameMode = modePause
				}
				for i := range screen.Buildings {
					if screen.Buildings[i].didCollide(screen.Bullet) {
						// Collision
						screen.animating = false
						break
					}
				}
			} else {
				// Bullet went off the sides of the screen
				screen.animating = false
			}
		}
	}
}

func (screen *mainScreen) drawScreen(style style) {
	// Draw Landscape
	var x int
	for i := range screen.Buildings {
		screen.Buildings[i].draw(x)
		x += screen.Buildings[i].width
	}
	if screen.GameMode == modeRun {
		// Draw Projectile(s)
		if screen.Bullet != nil {
			screen.Bullet.draw()
		}
	} else if screen.GameMode == modeRunInput {
		// Draw inputs
		if screen.PlayerTurn == 1 {
			angleText := fmt.Sprintf("Angle: %d", screen.Player1.projAngle)
			speedText := fmt.Sprintf("Speed: %d", screen.Player1.projSpeed)
			termboxUtil.DrawStringAtPoint(angleText, 0, 0, style.defaultFg, style.defaultBg)
			termboxUtil.DrawStringAtPoint(speedText, 0, 1, style.defaultFg, style.defaultBg)
			termboxUtil.DrawStringAtPoint("'space' to fire", 0, 2, style.defaultFg, style.defaultBg)
		} else {
			angleText := fmt.Sprintf("Angle: %d", screen.Player2.projAngle)
			speedText := fmt.Sprintf("Speed: %d", screen.Player2.projSpeed)
			termboxUtil.DrawStringAtPoint(angleText, ScreenWidth-11, 0, style.defaultFg, style.defaultBg)
			termboxUtil.DrawStringAtPoint(speedText, ScreenWidth-11, 1, style.defaultFg, style.defaultBg)
			termboxUtil.DrawStringAtPoint("'space' to fire", ScreenWidth-15, 2, style.defaultFg, style.defaultBg)
		}
	}

	// Draw Player 1
	screen.Player1.draw()
	// Draw Player 2
	screen.Player2.draw()

	if screen.GameMode == modePause {
		// Draw the pause menu
		screen.PauseMenu.Draw()
	}
}

func (screen *mainScreen) getRndPosForBuilding(i int) (int, int) {
	retY := ScreenHeight - screen.Buildings[i].height
	bldStX := 0
	for idx := 0; idx < i; idx++ {
		bldStX += screen.Buildings[idx].width
	}
	retX := screen.r.Intn(screen.Buildings[i].width-5) + bldStX
	return retX, retY
}

func getSeedFromString(seed string) int64 {
	// Does this algorithm work for string->seed generation?
	// ~\_(o.o)_/~ - seems to.
	var ret int64
	for i, k := range seed {
		ret += int64(k) * int64(i)
	}
	return ret
}

func degToRad(d int) float64 {
	return (float64(d) * (math.Pi / float64(180)))
}

type projectile struct {
	x, y           int
	startX, startY int
	speed, angle   int
	gravity        float64
	launchTime     time.Time
}

func (p *projectile) init(pl *player) {
	p.launchTime = time.Now()
	p.angle = pl.projAngle
	p.speed = pl.projSpeed
	p.startX, p.startY = pl.GetClosestTrajectory()
	//p.startX, p.startY = pl.x+2, pl.y+2
	p.x = p.startX
	p.y = p.startY
}

func (p *projectile) update() {
	tm := time.Since(p.launchTime).Seconds()
	useSpeed := float64(p.speed)
	useX, useY := float64(p.startX), float64(p.startY)
	useA := degToRad(p.angle)
	p.x = int(useX + (useSpeed * math.Cos(useA) * tm))
	p.y = int(useY + (useSpeed*math.Sin(useA)*tm - p.gravity*tm*tm/2))
}

func (p *projectile) draw() {
	if p.y < 0 {
		termbox.SetCell(p.x, 0, '^', termbox.ColorYellow, termbox.ColorBlack)
	} else {
		termbox.SetCell(p.x, p.y, '0', termbox.ColorYellow, termbox.ColorBlack)
	}
}

type player struct {
	x, y      int
	projSpeed int
	projAngle int
	gravity   float64
	baseColor termbox.Attribute
	turn      bool
	dead      bool
}

func (p *player) draw() {
	termbox.SetCell(p.x, p.y-4, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+1, p.y-4, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+2, p.y-4, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+3, p.y-4, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+4, p.y-4, ' ', p.baseColor, p.baseColor)

	termbox.SetCell(p.x, p.y-3, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+2, p.y-3, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+4, p.y-3, ' ', p.baseColor, p.baseColor)
	if p.dead {
		termbox.SetCell(p.x+1, p.y-3, 'X', termbox.ColorRed, termbox.ColorBlack)
		termbox.SetCell(p.x+3, p.y-3, 'X', termbox.ColorRed, termbox.ColorBlack)
	} else {
		termbox.SetCell(p.x+1, p.y-3, '@', termbox.ColorBlack, termbox.ColorWhite)
		termbox.SetCell(p.x+3, p.y-3, '@', termbox.ColorBlack, termbox.ColorWhite)
	}

	termbox.SetCell(p.x, p.y-2, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+1, p.y-2, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+2, p.y-2, 'w', termbox.ColorWhite, p.baseColor)
	termbox.SetCell(p.x+3, p.y-2, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+4, p.y-2, ' ', p.baseColor, p.baseColor)

	termbox.SetCell(p.x, p.y-1, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+1, p.y-1, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+2, p.y-1, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+3, p.y-1, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+4, p.y-1, ' ', p.baseColor, p.baseColor)

	termbox.SetCell(p.x, p.y, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+1, p.y, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+2, p.y, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+3, p.y, ' ', p.baseColor, p.baseColor)
	termbox.SetCell(p.x+4, p.y, ' ', p.baseColor, p.baseColor)

	// Now draw the arms
	if p.turn {
		bulletHandX, bulletHandY := p.GetBulletHandPos()
		termbox.SetCell(bulletHandX, bulletHandY, 'X', termbox.ColorRed|termbox.AttrBold, termbox.ColorBlack)
	}
}

func (p *player) didCollide(pr *projectile) bool {
	if pr.x >= p.x && pr.x <= p.x+4 {
		return pr.y <= p.y && pr.y >= p.y-4
	}
	return false
}

func (p *player) GetClosestTrajectory() (int, int) {
	// Find the spot closest to the player in a direct line with the target
	bHx, bHy := p.GetBulletHandPos()
	gx, gy := p.x+2, p.y-2
	for gx >= p.x && gx <= p.x+4 && gy >= p.y-4 && gy <= p.y {
		if math.Abs(float64(bHx-gx)) > math.Abs(float64(bHy-gy)) {
			if bHx > gx {
				gx++
			} else {
				gx--
			}
		} else {
			if bHy > gy {
				gy++
			} else {
				gy--
			}
		}
	}
	return gx, gy
}

func (p *player) GetBulletHandPos() (int, int) {
	tm := 0.5
	useSpeed := float64(p.projSpeed)
	useX, useY := float64(p.x+2), float64(p.y-2)
	useA := degToRad(p.projAngle)
	retX := int(useX + (useSpeed * math.Cos(useA) * tm))
	retY := int(useY + (useSpeed*math.Sin(useA)*tm - p.gravity*tm*tm/2))
	return retX, retY
}

type building struct {
	startX        int
	width, height int
	color         termbox.Attribute
	windowsOn     []int
}

func (b *building) draw(x int) {
	for i := 0; i < b.height; i++ {
		for j := 0; j < b.width; j++ {
			c := b.color
			/* TODO: Windows
			if i > 0 && i < b.height && j > 0 && j < b.width {
				if i%2 == 1 && j%2 == 1 {
					c = termbox.ColorBlack
				}
			}
			*/
			termbox.SetCell(x+j, ScreenHeight-i, ' ', c, c)
		}
	}
}

func (b *building) didCollide(p *projectile) bool {
	if p.x >= b.startX && p.x <= b.startX+b.width {
		return p.y >= ScreenHeight-b.height
	}
	return false
}