using Test

using Sbplib.SbpOperators
using Sbplib.Grids
using Sbplib.RegionIndices
using Sbplib.LazyTensors

import Sbplib.SbpOperators.Stencil
import Sbplib.SbpOperators.VolumeOperator
import Sbplib.SbpOperators.volume_operator
import Sbplib.SbpOperators.odd
import Sbplib.SbpOperators.even

@testset "VolumeOperator" begin
    inner_stencil = CenteredStencil(1/4, 2/4, 1/4)
    closure_stencils = (Stencil(1/2, 1/2; center=1), Stencil(0.,1.; center=2))
    g_1D = EquidistantGrid(11,0.,1.)
    g_2D = EquidistantGrid((11,12),(0.,0.),(1.,1.))
    g_3D = EquidistantGrid((11,12,10),(0.,0.,0.),(1.,1.,1.))
    @testset "Constructors" begin
        @testset "1D" begin
            op = VolumeOperator(inner_stencil,closure_stencils,(11,),even)
            @test op == VolumeOperator(g_1D,inner_stencil,closure_stencils,even)
            @test op == volume_operator(g_1D,inner_stencil,closure_stencils,even,1)
            @test op isa LazyTensor{T,1,1} where T
        end
        @testset "2D" begin
            op_x = volume_operator(g_2D,inner_stencil,closure_stencils,even,1)
            op_y = volume_operator(g_2D,inner_stencil,closure_stencils,even,2)
            Ix = IdentityTensor{Float64}((11,))
            Iy = IdentityTensor{Float64}((12,))
            @test op_x == VolumeOperator(inner_stencil,closure_stencils,(11,),even)⊗Iy
            @test op_y == Ix⊗VolumeOperator(inner_stencil,closure_stencils,(12,),even)
            @test op_x isa LazyTensor{T,2,2} where T
            @test op_y isa LazyTensor{T,2,2} where T
        end
        @testset "3D" begin
            op_x = volume_operator(g_3D,inner_stencil,closure_stencils,even,1)
            op_y = volume_operator(g_3D,inner_stencil,closure_stencils,even,2)
            op_z = volume_operator(g_3D,inner_stencil,closure_stencils,even,3)
            Ix = IdentityTensor{Float64}((11,))
            Iy = IdentityTensor{Float64}((12,))
            Iz = IdentityTensor{Float64}((10,))
            @test op_x == VolumeOperator(inner_stencil,closure_stencils,(11,),even)⊗Iy⊗Iz
            @test op_y == Ix⊗VolumeOperator(inner_stencil,closure_stencils,(12,),even)⊗Iz
            @test op_z == Ix⊗Iy⊗VolumeOperator(inner_stencil,closure_stencils,(10,),even)
            @test op_x isa LazyTensor{T,3,3} where T
            @test op_y isa LazyTensor{T,3,3} where T
            @test op_z isa LazyTensor{T,3,3} where T
        end
    end

    @testset "Sizes" begin
        @testset "1D" begin
            op = volume_operator(g_1D,inner_stencil,closure_stencils,even,1)
            @test range_size(op) == domain_size(op) == size(g_1D)
        end

        @testset "2D" begin
            op_x = volume_operator(g_2D,inner_stencil,closure_stencils,even,1)
            op_y = volume_operator(g_2D,inner_stencil,closure_stencils,even,2)
            @test range_size(op_y) == domain_size(op_y) ==
                  range_size(op_x) == domain_size(op_x) == size(g_2D)
        end
        @testset "3D" begin
            op_x = volume_operator(g_3D,inner_stencil,closure_stencils,even,1)
            op_y = volume_operator(g_3D,inner_stencil,closure_stencils,even,2)
            op_z = volume_operator(g_3D,inner_stencil,closure_stencils,even,3)
            @test range_size(op_z) == domain_size(op_z) ==
                  range_size(op_y) == domain_size(op_y) ==
                  range_size(op_x) == domain_size(op_x) == size(g_3D)
        end
    end

    op_x = volume_operator(g_2D,inner_stencil,closure_stencils,even,1)
    op_y = volume_operator(g_2D,inner_stencil,closure_stencils,odd,2)
    v = zeros(size(g_2D))
    Nx = size(g_2D)[1]
    Ny = size(g_2D)[2]
    for i = 1:Nx
        v[i,:] .= i
    end
    rx = copy(v)
    rx[1,:] .= 1.5
    rx[Nx,:] .= (2*Nx-1)/2
    ry = copy(v)
    ry[:,Ny-1:Ny] = -v[:,Ny-1:Ny]

    @testset "Application" begin
        @test op_x*v ≈ rx rtol = 1e-14
        @test op_y*v ≈ ry rtol = 1e-14

        @test (op_x*rand(ComplexF64,size(g_2D)))[2,2] isa ComplexF64
    end

    @testset "Regions" begin
        @test (op_x*v)[Index(1,Lower),Index(3,Interior)] ≈ rx[1,3] rtol = 1e-14
        @test (op_x*v)[Index(2,Lower),Index(3,Interior)] ≈ rx[2,3] rtol = 1e-14
        @test (op_x*v)[Index(6,Interior),Index(3,Interior)] ≈ rx[6,3] rtol = 1e-14
        @test (op_x*v)[Index(10,Upper),Index(3,Interior)] ≈ rx[10,3] rtol = 1e-14
        @test (op_x*v)[Index(11,Upper),Index(3,Interior)] ≈ rx[11,3] rtol = 1e-14

        @test_throws BoundsError (op_x*v)[Index(3,Lower),Index(3,Interior)]
        @test_throws BoundsError (op_x*v)[Index(9,Upper),Index(3,Interior)]

        @test (op_y*v)[Index(3,Interior),Index(1,Lower)] ≈ ry[3,1] rtol = 1e-14
        @test (op_y*v)[Index(3,Interior),Index(2,Lower)] ≈ ry[3,2] rtol = 1e-14
        @test (op_y*v)[Index(3,Interior),Index(6,Interior)] ≈ ry[3,6] rtol = 1e-14
        @test (op_y*v)[Index(3,Interior),Index(11,Upper)] ≈ ry[3,11] rtol = 1e-14
        @test (op_y*v)[Index(3,Interior),Index(12,Upper)] ≈ ry[3,12] rtol = 1e-14

        @test_throws BoundsError (op_y*v)[Index(3,Interior),Index(10,Upper)]
        @test_throws BoundsError (op_y*v)[Index(3,Interior),Index(3,Lower)]
    end

    @testset "Inferred" begin
        @test_skip @inferred apply(op_x, v,1,1)
        @inferred apply(op_x, v, Index(1,Lower),Index(1,Lower))
        @inferred apply(op_x, v, Index(6,Interior),Index(1,Lower))
        @inferred apply(op_x, v, Index(11,Upper),Index(1,Lower))
        @test_skip @inferred apply(op_y, v,1,1)
        @inferred apply(op_y, v, Index(1,Lower),Index(1,Lower))
        @inferred apply(op_y, v, Index(1,Lower),Index(6,Interior))
        @inferred apply(op_y, v, Index(1,Lower),Index(11,Upper))
    end
end