using LinearAlgebra

struct Grid{T}
    cols::Int
    rows::Int
    dim::Int
    domainCol::T
    domainRow::T
    deltaCol::T
    deltaRow::T
    concentrations::Ref{Matrix{T}}
    alphaX::Matrix{T}
    alphaY::Union{Matrix{T},Nothing}
    alphaX_t::Union{Matrix{T},Nothing}
    alphaY_t::Union{Matrix{T},Nothing}

    # Constructor for 1D-Grid
    function Grid{T}(length::Int, alpha::Matrix{T}) where {T}
        if length <= 3
            throw(ArgumentError("Given grid length too small. Must be greater than 3."))
        end
        if size(alpha, 1) != 1 || size(alpha, 2) != length
            error("Given matrix of alpha coefficients mismatch with Grid dimensions!")
        end

        new{T}(length, 1, 1, T(length), 0, T(1), 0, Ref(fill(T(0), 1, length)), alpha, nothing, nothing, nothing)
    end

    # Constructor for 2D-Grid
    function Grid{T}(rows::Int, cols::Int, alphaX::Matrix{T}, alphaY::Matrix{T}) where {T}
        if rows <= 3 || cols <= 3
            throw(ArgumentError("Given grid dimensions too small. Must each be greater than 3."))
        end
        if size(alphaX) != (rows, cols) || size(alphaY) != (rows, cols)
            error("Given matrices of alpha coefficients mismatch with Grid dimensions!")
        end

        alphaX_t = alphaX'
        alphaY_t = alphaY'

        new{T}(cols, rows, 2, T(cols), T(rows), T(1), T(1), Ref(fill(T(0), rows, cols)), alphaX, alphaY, alphaX_t, alphaY_t)
    end
end

function getAlphaX(grid::Grid{T})::Matrix{T} where {T}
    grid.alphaX
end

function getAlphaY(grid::Grid{T})::Matrix{T} where {T}
    grid.alphaY
end

function getAlphaX_t(grid::Grid{T})::Matrix{T} where {T}
    grid.alphaX_t
end

function getAlphaY_t(grid::Grid{T})::Matrix{T} where {T}
    grid.alphaY_t
end

function getConcentrations(grid::Grid{T})::Matrix{T} where {T}
    grid.concentrations[]
end

function setConcentrations!(grid::Grid{T}, new_concentrations::Matrix{T}) where {T}
    grid.concentrations[] = new_concentrations
end

function getCols(grid::Grid{T})::Int where {T}
    grid.cols
end

function getRows(grid::Grid{T})::Int where {T}
    grid.rows
end