local World = {
    GAME_W = 1024,
    GAME_H = 768,
    FIELD_SIZE = 4000,
    visibleH = 768,
    scale = 1,
    offsetX = 0,
    offsetY = 0,
    screenW = 0,
    screenH = 0,
    -- Viewport regions (screen pixels)
    radarH = 0,
    viewY = 0,
    viewH = 0,
    -- Classic vector-arcade thresholds (defaults matching the most common DIP
    -- switch settings documented in arcade-preservation records).
    MISSILE_THRESHOLD = 10000,       -- binary: below score, no missiles; at/above, missiles mix in
    SUPERTANK_MISSILE_COUNT = 6,     -- super tanks replace slow tanks after this many missiles have launched
    SAUCER_THRESHOLD = 2000,         -- saucer becomes eligible
    SAUCER_MIN_DELAY = 0,
    SAUCER_MAX_DELAY = 17,
    EVADE_TANK_TIME_MIN = 48,        -- if current tank stays alive this long, swap it for a missile (arcade: 48-64s)
    EVADE_TANK_TIME_MAX = 64,
    RESPAWN_SPAWN_BEAT = 2.5,        -- seconds between enemy death and next spawn
    FIRE_SUPPRESSION = 2.0,          -- seconds after enemy spawn during which it cannot fire (arcade rule)
    -- State
    state = "title",
    score = 0,
    highScore = 0,
    lives = 3,
    nextExtraLife = 15000,
    enemiesDestroyed = 0,
    gameOverTimer = 0,
    spawnTimer = 0,
    saucerCooldown = 0,              -- seconds until next saucer eligible
    missilesLaunched = 0,            -- total missile spawns this game (gates super-tank transition)
    evadeDeadline = 0,               -- RNG'd 48..64s lifetime limit for the current tank
}

function World.resize(w, h)
    if not w or not h then w, h = love.graphics.getDimensions() end
    World.screenW = w
    World.screenH = h
    World.scale = w / World.GAME_W
    World.visibleH = h / World.scale
    World.offsetX = 0
    World.offsetY = 0
    -- Viewport layout
    World.radarH = math.floor(h * 0.18)
    World.viewY = World.radarH
    World.viewH = h - World.radarH
end

function World.ensureScale()
    local w, h = love.graphics.getDimensions()
    if w ~= World.screenW or h ~= World.screenH then
        World.resize(w, h)
        local Fonts = require("rendering.fonts")
        Fonts.init(World.scale)
        local Camera = require("game.camera")
        Camera.initViewport()
    end
end

function World.wrapField(x, z)
    local S = World.FIELD_SIZE
    return (x % S + S) % S, (z % S + S) % S
end

function World.wrappedDelta(a, b, size)
    local d = b - a
    if d > size / 2 then d = d - size end
    if d < -size / 2 then d = d + size end
    return d
end

function World.wrappedDist(x1, z1, x2, z2)
    local S = World.FIELD_SIZE
    local dx = World.wrappedDelta(x1, x2, S)
    local dz = World.wrappedDelta(z1, z2, S)
    return dx, dz, math.sqrt(dx*dx + dz*dz)
end

function World.addScore(points)
    World.score = World.score + points
    local granted = false
    while World.score >= World.nextExtraLife do
        World.lives = World.lives + 1
        granted = true
        if World.nextExtraLife < 100000 then
            World.nextExtraLife = 100000
        else
            World.nextExtraLife = World.nextExtraLife + 100000
        end
    end
    if granted then
        local ok, Sounds = pcall(require, "audio.sounds")
        if ok and Sounds.play then Sounds.play("extra_life") end
    end
    if World.score > World.highScore then
        World.highScore = World.score
    end
end

return World