abstract type Env <: AbstractEnv end

mutable struct EnvSharedProps{n_state_dims}
    n_actions::Int64
    action_space::Vector{SVector{2,Float64}}
    action_id_space::OneTo{Int64}

    n_states::Int64
    state_id_tensor::Array{Int64,n_state_dims}
    state_id_space::OneTo{Int64}
    state_id::Int64

    reward::Float64
    terminated::Bool

    function EnvSharedProps(
        n_states::Int64, # Can be different from the sum of state_id_tensor_dims
        state_id_tensor_dims::NTuple{n_state_dims,Int64};
        n_v_actions::Int64=2,
        n_ω_actions::Int64=3,
        max_v::Float64=40.0,
        max_ω::Float64=π / 2,
    ) where {n_state_dims}
        @assert n_v_actions > 1
        @assert n_ω_actions > 1
        @assert max_v > 0
        @assert max_ω > 0

        v_action_space = range(; start=0.0, stop=max_v, length=n_v_actions)
        ω_action_space = range(; start=-max_ω, stop=max_ω, length=n_ω_actions)

        n_actions = n_v_actions * n_ω_actions

        action_space = Vector{SVector{2,Float64}}(undef, n_actions)

        ind = 1
        for v in v_action_space
            for ω in ω_action_space
                action_space[ind] = SVector(v, ω)
                ind += 1
            end
        end

        action_id_space = OneTo(n_actions)

        state_id_tensor = Array{Int64,n_state_dims}(undef, state_id_tensor_dims)

        id = 1
        for ind in eachindex(state_id_tensor)
            state_id_tensor[ind] = id
            id += 1
        end

        state_id_space = OneTo(n_states)

        return new{n_state_dims}(
            n_actions,
            action_space,
            action_id_space,
            n_states,
            state_id_tensor,
            state_id_space,
            INITIAL_STATE_IND,
            INITIAL_REWARD,
            false,
        )
    end
end

function reset!(env::Env)
    env.shared.terminated = false

    return nothing
end

function RLBase.state_space(env::Env)
    return env.shared.state_id_space
end

function RLBase.state(env::Env)
    return env.shared.state_id
end

function RLBase.action_space(env::Env)
    return env.shared.action_id_space
end

function RLBase.reward(env::Env)
    return env.shared.reward
end

function RLBase.is_terminated(env::Env)
    return env.shared.terminated
end