FromTheDepths-AutoTarget.lua

function Update()
    target = acquireTarget(800)
    if target ~= nil then
        fireAt(target)
    end 
end

function acquireTarget(minDistance)
    target = nil
    for i = 0, I:GetNumberOfMainframes(), 1 do
        for j = 0, I:GetNumberOfTargets(i), 1 do
            t = I:GetTargetInfo(i, j)
            if t.Valid and (target == nil or t.Priority < target.Priority) and t.Position.GroundDistance < minDistance then
                target = t
            end
        end
    end
    return target
end

function fireAt(target)
    for i = 0, I:GetWeaponCount(), 1 do
        weaponInfo = I:GetWeaponInfo(i)
        if weaponInfo.Valid then
            weaponPosition = I:GetWeaponInfo(i).GlobalPosition
            targetPosition = target.AimPointPosition
            I:AimWeaponInDirection(
                i,
                targetPosition.x- weaponPosition.x,
                targetPosition.y - weaponPosition.y,
                targetPosition.z - weaponPosition.z,
                0)
            I:FireWeapon(i, 0)
        end
    end
end

I:BindUpdateFunction(Update)