--PHYSICS ENGINE

local downForce = {}

local physics = {
    collision = function(body1, body2)
        return(
            {
                hit =   body1.AbsolutePosition.X + body1.AbsoluteSize.X > body2.AbsolutePosition.X and
                        body2.AbsolutePosition.X + body2.AbsoluteSize.X > body1.AbsolutePosition.X and
                        body1.AbsolutePosition.Y + body1.AbsoluteSize.Y > body2.AbsolutePosition.Y and
                        body2.AbsolutePosition.Y + body2.AbsoluteSize.Y > body1.AbsolutePosition.Y,

                side = {
                    left =      body2.AbsolutePosition.X + body2.AbsoluteSize.X - body1.AbsolutePosition.X < 5,
                    right =     body1.AbsolutePosition.X + body1.AbsoluteSize.X - body2.AbsolutePosition.X < 5,
                    top =       body2.AbsolutePosition.Y + body2.AbsoluteSize.Y - body1.AbsolutePosition.Y < 5,
                    bottom =    body1.AbsolutePosition.Y + body1.AbsoluteSize.Y - body2.AbsolutePosition.Y < 5
                }
            }
        )
    end,
    updateGravity = function(mode, name, ...)
        if not downForce[name] then
            downForce[name] = 0
        end
        local args = unpack({...})
        if mode == "increase" then
            downForce[name] = downForce[name] + args.inc
        elseif mode == "reset" then
            downForce[name] = 0
        elseif mode == "jump" then
            downForce[name] = -10
        end
        return downForce[name]
    end
}

return physics

--ACTUAL GAME STARTS HERE

game.StarterGui:SetCoreGuiEnabled("All", false)

local assets = {162359401, 85926303, 36527138}
for i, v in pairs(assets) do
    game:GetService("ContentProvider"):Preload("rbxassetid://" .. tostring(v))
end

local player = game.Players.LocalPlayer
repeat wait() until player.Character player.Character:Destroy()
local mouse = player:GetMouse()
local objects = script.Parent:WaitForChild("GameObjects")
local physics = require(Workspace.Physics)
local anchor = false
local anchorPos;
local isDown = {}
local bullets = {}
local enemies = {}
local enemyBullets = {}
local count = 0
local score = 0
local limit = 200

physics.gravity = 5

local player = {
    body = objects:WaitForChild("Player"),
    canJump = true,
    speed = 5,
    bulletSpeed = 10,
    upForce, downForce = 0, 0,
    lastSpot, lastShot;
}

function spawnBullet(side)
    if player.lastShot then
        if tick() - player.lastShot < 0.2 then
            return
        end
    end
    player.lastShot = tick()
    local velocity = side == "left" and -player.bulletSpeed or player.bulletSpeed
    local bullet = Instance.new("ImageLabel", objects)
    bullet.Size = UDim2.new(0, 50, 0, 10)
    bullet.Position = UDim2.new(
        player.body.Position.X.Scale,
        player.body.Position.X.Offset + (velocity * 6),
        player.body.Position.Y.Scale,
        player.body.Position.Y.Offset + ((player.body.Size.Y.Offset / 2) - (bullet.Size.Y.Offset / 2))
    )
    bullet.BackgroundTransparency = 1
    bullet.Image = "rbxassetid://85926303"
    bullet.ZIndex = 3
    table.insert(bullets, {body = bullet, speed = velocity, move = true, touch = function(hit)
        if hit.body.Name:find("Enemy") then
            hit.dead = true
            hit.body:Destroy()
            for i, v in pairs(enemies) do
                if v.body.Name == hit.body.Name then
                    table.remove(enemies, i)
                    break
                end
            end
        end
    end
    })
end

function spawnEnemyBullet(side, enemy)
    local velocity = side == "left" and 10 or -10
    local bullet = Instance.new("ImageLabel", objects)
    bullet.Size = UDim2.new(0, 50, 0, 10)
    bullet.Position = UDim2.new(
        enemy.body.Position.X.Scale,
        enemy.body.Position.X.Offset + (velocity * 6),
        enemy.body.Position.Y.Scale,
        enemy.body.Position.Y.Offset + ((enemy.body.Size.Y.Offset / 2) - (bullet.Size.Y.Offset / 2))
    )
    bullet.BackgroundTransparency = 1
    bullet.Image = "rbxassetid://36527138"
    bullet.ZIndex = 3
    table.insert(enemyBullets, {body = bullet, speed = velocity, move = true, touch = function(hit)
        if hit.body.Name == "Player" then
            hit.body:Destroy()
            wait(2)
            game:GetService("TeleportService"):Teleport(145098778)
        end
    end
    })
end

mouse.KeyDown:connect(function(key)
    isDown[key:lower()] = {
        true,
        key:lower() == "a" and UDim2.new(0, -player.speed, 0, 0) or
        key:lower() == "d" and UDim2.new(0, player.speed, 0, 0)
    }
    if key:byte() == 32 and player.canJump then
        anchor = false
        player.downForce = physics.updateGravity("jump", player.body.Name)
    elseif key:lower() == "l" then
        spawnBullet("right")
    elseif key:lower() == "k" then
        spawnBullet("left")
    end
end)

mouse.KeyUp:connect(function(key)
    isDown[key:lower()][1] = false
end)

local physicsBodies = {
    {body = objects:WaitForChild("Ground")},
    {body = objects:WaitForChild("Plat1")},
    {body = objects:WaitForChild("Plat2")},
    {body = script.Parent:WaitForChild("Wall1")},
    {body = script.Parent:WaitForChild("Wall2")},
    {body = script.Parent:WaitForChild("Wall4")},
}

function explode(bullet)
    coroutine.wrap(function()
        bullet.move = false
        bullet.body.Image = "rbxassetid://162359401"
        local size = bullet.body.Size
        local position = bullet.body.Position
        for x = 1, 50, 5 do
            wait()
            bullet.body.Size = size + UDim2.new(0, x, 0, x+3)
            bullet.body.Position = position - UDim2.new(0, x/2, 0, (x/2)+1.5)
        end
        bullet.body:Destroy()
    end)()
end

game:GetService("RunService").RenderStepped:connect(function()
    --handle physics and player movement
    for _, v in pairs(isDown) do
        if v[1] and v[2] then
            player.body.Position = player.body.Position + v[2]
        end
    end
    local gotHit;
    for _, object in pairs(physicsBodies) do
        local collision = physics.collision(object.body, player.body)
        local ignore;
        if collision.hit then
            if not collision.side.left and not collision.side.right then
                gotHit = true
            end
            if collision.side.top then
                anchor = true
                anchorPos = {object.body.Position.Y.Scale, object.body.Position.Y.Offset}
            end
            if not ignore then
                if player.lastSpot then
                    player.body.Position = player.lastSpot
                end
            end
        end
    end
    if not gotHit then
        player.canJump = false
        player.lastSpot = player.body.Position
        player.downForce = physics.updateGravity("increase", player.body.Name, {inc = 0.5})
    else
        player.canJump = true
        player.downForce = physics.updateGravity("reset", player.body.Name)
    end
    if anchor then
        player.body.Position = UDim2.new(
            player.body.Position.X.Scale,
            player.body.Position.X.Offset,
            anchorPos[1],
            anchorPos[2] - player.body.Size.Y.Offset
        )
        physics.updateGravity("reset", player.body.Name)
        player.canJump = true
    end
    player.body.Position = player.body.Position + UDim2.new(0, 0, 0, player.downForce)

    --handle bullets
    for i, bullet in pairs(bullets) do
        if bullet.body and bullet.move then
            bullet.body.Position = bullet.body.Position + UDim2.new(0, bullet.speed, 0, 0)
            for _, object in pairs(physicsBodies) do
                if physics.collision(bullet.body, object.body).hit then
                    explode(bullet)
                end
            end
            for _, enemy in pairs(enemies) do
                if physics.collision(bullet.body, enemy.body).hit then
                    explode(bullet)
                    bullet.touch(enemy)
                    score = score + 1
                    script.Parent:WaitForChild("Score").Text = score
                end
            end
        end
    end

    --handle enemies and enemy physics
    count = count + 1
    if count % limit == 0 then
        limit = limit - 1
        print("spawned enemy #" .. count)
        local enemy = player.body:clone()
        enemy.Parent = objects
        enemy.Name = "Enemy" .. tostring(count)
        enemy.BackgroundColor3 = Color3.new(1, 1, 1)
        enemy.BorderColor3 = Color3.new(1, 0, 0)
        enemy.Position = UDim2.new(0, math.random(60, 680), 0, -50)
        table.insert(enemies, {
            body = enemy,
            downForce = 0,
            lastSpot, hasLanded, dead;
        })
    end
    for _, enemy in pairs(enemies) do
        if enemy.body then
            local gotHit;
            enemy.lastSpot = enemy.body.Position
            enemy.downForce = physics.updateGravity("increase", enemy.body.Name, {inc = 0.1})
            for _, object in pairs(physicsBodies) do
                local collision = physics.collision(object.body, enemy.body)
                if collision.hit then
                    gotHit = true
                    if collision.side.top then
                        enemy.body.Position = UDim2.new(
                            enemy.body.Position.X.Scale,
                            enemy.body.Position.X.Offset,
                            object.body.Position.Y.Scale,
                            object.body.Position.Y.Offset - enemy.body.Size.Y.Offset
                        )
                    end
                    enemy.body.Position = enemy.lastSpot
                    enemy.hasLanded = true
                end
            end
            if not gotHit then
                enemy.body.Position = enemy.body.Position + UDim2.new(0, 0, 0, enemy.downForce)
            end
            if enemy.hasLanded and not enemy["IS_SHOOTING"] then
                enemy["IS_SHOOTING"] = true
                coroutine.wrap(function()
                    while wait(math.random(1, 5)) do
                        if enemy.dead or not enemy.body then break end
                        spawnEnemyBullet(math.random() < 0.5 and "left" or "right", enemy)
                    end
                end)()
            end
        end
    end

    --handle enemy bullets
    for i, bullet in pairs(enemyBullets) do
        if bullet.move and bullet.body then
            bullet.body.Position = bullet.body.Position + UDim2.new(0, bullet.speed, 0, 0)
            for _, object in pairs(physicsBodies) do
                if physics.collision(bullet.body, object.body).hit then
                    explode(bullet)
                end
            end
            if physics.collision(bullet.body, player.body).hit then
                explode(bullet)
                bullet.touch(player)
            end
        end
    end
end)