# This is a module for 8.08 - 8.S308 numerics recitation.
module Rec
    #parameters of the model
    mutable struct Param
        dt::Float64             # time step
        L::Int64                # number of sites per dimension
        J::Float64              # interaction strength
        T::Float64              # Temperature
    end

    #constructor
    function setParam(L, J, T)
        param = Param(0, L, J, T)
        return param
    end

    #state variables of the model
    mutable struct State
        t::Float64                  # current time
        s::Array{Int8, 2}           # spin array
    end

    #constructor
    function setState(param)
        s = zeros(Float64, param.L, param.L)
        state = State(0, s)
        return state
    end
end

function tower_sampling(w, W, rng)
    
    ### Implement your tower sampling algorithm
    index = 1

    return index
end

function run_simulation!(state, param, t_run, rng)

    t_now = state.t     # time at the beginning of your simulation
    L, J, T = param.L, param.J, param.T       # loading parameters

    beta = 1/T
    
    x, y = 0, 0
    ei, ef = 0.0, 0.0
    m = 0.0

    move = 0
    w = zeros(Float64, 2)
    W = 0.0

    # move(1) = flip spin, 1 -> -1 or -1 -> 1
    # move(2) = don't do anything

    dt = 1/exp(4*J/T)

    while state.t < t_now + t_run
        # I selected a spin location for you
        x = rand(rng, 1:L)
        y = rand(rng, 1:L)

        ### Please write your algorithm for simulation the model here 
        # magnetization of the neighbors felt by the spin
        m = 

        # energy of the initial configuration
        ei = 
        # energy of the final configuration
        ef =

        # your transition probabilities
        w[1] = 
        w[2] = 

        W = sum(w)

        move = tower_sampling(w, W, rng)

        if move==1
            state.s[x,y] =
        elseif move==2
            state.s[x,y] = 
        end

        state.t += dt/(L^2)
    end
end

function get_movie!(state, param, rng, t_gap, n_frame, in_fps)
    x_range = range(1,L, length = L)    # lattice x coordinates    
    y_range = range(1,L, length = L)    # lattice y coordinates

    anim = @animate for frame in 1:n_frame
        run_simulation!(state, param, t_gap, rng)

        heatmap(x_range, y_range, transpose(state.s), 
        size=(600,600), c=cgrad(:inferno), clim=(-1.2,1.2), aspectratio=1, xlabel="x", ylabel="y")
    end

    name = "Rec11_Ising.gif"
    gif(anim, name, fps=in_fps)
end