local Vec3 = require "lib/vec3"
local tree = require "lib/tree"

local EPSILON = 0.001

--- @class (exact) Camera
--- @field position Vec3
--- @field velocity Vec3
--- @field speed number
--- @field pixelsPerMeter integer
local camera = {
    position = Vec3 {},
    velocity = Vec3 {},
    speed = 5,
    pixelsPerMeter = 100
}

---@todo Отрефакторить и вынести кнопки управления в controls, не должно быть таких ужасных проверок
function camera:update(dt)
    local ws = tree.instance().wheelscroll
    if ws.delta:length() > 0 then
        local worldDelta = ws.delta:scale(1 / self.pixelsPerMeter):scale(dt):scale(self.speed)
        self.velocity = self.velocity + worldDelta
    elseif love.keyboard.isDown("w") or love.keyboard.isDown("a") or love.keyboard.isDown("s") or love.keyboard.isDown("d") then
        if love.keyboard.isDown("w") then self.velocity = self.velocity + Vec3({ 0, -1 }) end
        if love.keyboard.isDown("a") then self.velocity = self.velocity + Vec3({ -1 }) end
        if love.keyboard.isDown("s") then self.velocity = self.velocity + Vec3({ 0, 1 }) end
        if love.keyboard.isDown("d") then self.velocity = self.velocity + Vec3({ 1 }) end
        self.velocity = (self.velocity:normalize() or Vec3 {}):scale(self.speed):scale(dt)
    end

    self.position = self.position + self.velocity
    self.velocity = self.velocity -
        self.velocity * 5 *
        dt -- магическая формула, которая означает "экспоненциально замедлиться до нуля"
    if self.velocity:length() < EPSILON then self.velocity = Vec3 {} end
end

function camera:attach()
    love.graphics.push()
    love.graphics.scale(self.pixelsPerMeter)
    love.graphics.translate(-self.position.x, -self.position.y)
end

function camera:detach()
    love.graphics.pop()
end

--- @return Camera
local function new()
    return setmetatable({}, {
        __index = camera
    })
end

return { new = new }