module OptimMixture

import GLMakie as GLM
import DelimitedFiles as DF
import BenchmarkTools as BT
import UnicodePlots as UP
import NLopt
import LinearAlgebra: norm, mul!, axpy!, axpby!

import Logging
Logging.global_logger(Logging.ConsoleLogger(stderr, Logging.Info))

const ENERGIES = [2803, 2811, 2819, 2826, 2834, 2842, 2850, 2858, 2866, 2874,
  2882, 2890, 2897, 2905, 2913, 2921, 2929, 2937, 2945, 2953,
  2961, 2969, 2977, 2985, 2993, 3001, 3009, 3018, 3026, 3034,
  3042, 3050]

@kwdef struct Slab{T<:Real}
  energy::Int
  data::Matrix{T}
end

function load_slabs(; T::Type=Int, width::Int=512, height::Int=512)
  slabs = Slab[]
  i_min, i_max = typemax(Int), 0
  for e in ENERGIES
    slab::Slab{T} = Slab{T}(energy=e, data=DF.readdlm("test_sample/HeLa_F-SRS_512x512_$(e)cm-1.txt", ',', T))
    push!(slabs, slab)

    i_min, i_max = min(i_min, minimum(slab.data)), max(i_max, maximum(slab.data))

  end
  s = join(size(slabs[1].data), "x")
  @info "Loaded $(length(slabs)) $s slabs"
  return slabs, i_min, i_max
end

function E_loop(X::Matrix{Float64}, Y::Matrix{Float64})
  s = 0
  N, M = size(Y)
  m = size(X, 2)
  for i in 1:N
    for j in N+1:N+M
      x = 0
      for k in 1:m
        @inbounds x += X[i, k] * X[j, k]
      end
      @inbounds s += (x - Y[i, j-N])^2
    end
  end
  return s
end

function E!(X::Matrix{Float64}, Y::Matrix{Float64}, tmp::Matrix{Float64})
  N, M = size(Y)
  Q!(tmp, X, N)
  # roughly 6ms with N = 512*512, M = 32, m = 2
  # slighly faster than tmp .= tmp .- Y (7ms)
  # slighly faster than tmp .-= Y (7ms)
  axpy!(-1.0, Y, tmp)
  # roughly 2.5m
  # slightly faster than norm2(tmp)
  s = sum(x -> x^2, tmp)
  return s
end

function test_E(N::Int, M::Int, m::Int; benchmark::Bool=true)
  X = rand(N + M, m)
  Y = rand(N, M)

  tmp = zeros(N, M)

  E_from_loop = E_loop(X, Y)
  E_from_mul = E!(X, Y, tmp)

  @show abs(E_from_mul - E_from_loop)

  if benchmark
    @info "Running benchmarks..., this may take a while"
    show(stdout, "text/plain", BT.@benchmark E_loop($X, $Y))
    println()
    show(stdout, "text/plain", BT.@benchmark E!($X, $Y, $tmp))
  end
end


function Q!(dst::Matrix{Float64}, X::Matrix{Float64}, N::Int)
  N_plus_M, _ = size(X)
  # roughly 9ms with N = 512*512, M = 32, m = 2
  # could be sped up using StrideArray?
  mul!(dst, view(X, 1:N, :), view(X, N+1:N_plus_M, :)')
end

function Q_loop!(dst::Matrix{Float64}, X::Matrix{Float64}, N::Int)
  N_plus_M, m = size(X)
  # roughly 23.5ms with N = 512*512, M = 32, m = 2
  for i in 1:N
    for j in N+1:N_plus_M
      x = 0
      for k in 1:m
        @inbounds x += X[i, k] * X[j, k]
      end
      @inbounds dst[i, j-N] = x
    end
  end
end

function test_Q(N::Int, M::Int, m::Int; benchmark::Bool=true)
  X = rand(N + M, m)

  Q_from_loop = zeros(N, M)
  Q_from_mul = zeros(N, M)

  Q!(Q_from_mul, X, N)
  Q_loop!(Q_from_loop, X, N)

  @show norm(Q_from_mul - Q_from_loop)

  if benchmark
    @info "Running benchmarks..., this may take a while"
    show(stdout, "text/plain", BT.@benchmark Q!($Q_from_mul, $X, $N))
    println()
    show(stdout, "text/plain", BT.@benchmark Q_loop!($Q_from_loop, $X, $N))
  end
end

function DE_loop!(dst::Matrix{Float64}, X::Matrix{Float64}, Y::Matrix{Float64})
  dst_W = zeros(size(Y))
  DE_loop!!(dst, dst_W, X, Y)
end

function DE!!(dst::Matrix{Float64}, dst_W::Matrix{Float64}, X::Matrix{Float64}, Y::Matrix{Float64})
  N_plus_M, m = size(X)
  N, M = size(Y)
  # dst is the same size as X
  # we need storage of size Y
  Q!(dst_W, X, N)
  # compute W = 2(Q(X) - Y)
  axpby!(-2.0, Y, 2.0, dst_W)
  mul!(view(dst, 1:N, :), dst_W, view(X, N+1:N_plus_M, :))
  mul!(view(dst, N+1:N_plus_M, :), dst_W', view(X, 1:N, :))
end

function DE_loop!!(dst::Matrix{Float64}, dst_W::Matrix{Float64}, X::Matrix{Float64}, Y::Matrix{Float64})
  _, m = size(X)
  N, M = size(Y)
  # dst is the same size as X
  # we need storage of size Y
  Q_loop!(dst_W, X, N)
  # compute W = Q(X) - Y
  dst_W .-= Y
  for k in 1:m
    for i in 1:N
      x = 0
      for j in 1:M
        @inbounds x += dst_W[i, j] * X[N+j, k]
      end
      @inbounds dst[i, k] = x
    end
    for j in 1:M
      x = 0
      for i in 1:N
        @inbounds x += dst_W[i, j] * X[i, k]
      end
      @inbounds dst[N+j, k] = x
    end
  end
  dst .*= 2
end

function check_derivative_E(N::Int, M::Int, m::Int; loop::Bool=false)
  X = rand(N + M, m)
  Y = rand(N, M)
  V = rand(N + M, m) .- 0.5

  EX = E_loop(X, Y)
  grad_EX = zeros(size(X))
  tmp = zeros(size(Y))
  if loop
    DE_loop!!(grad_EX, tmp, X, Y)
  else
    DE!!(grad_EX, tmp, X, Y)
  end

  eps = [10.0^k for k in 1:-1:-12]
  errors = zeros(size(eps))

  for i in eachindex(eps)
    if loop
      EX_V_true = E_loop(X + eps[i] * V, Y)
    else
      EX_V_true = E!(X + eps[i] * V, Y, tmp)
    end
    EX_V_approx = EX + eps[i] * sum(grad_EX .* V)
    # @show EX_V_true
    # @show EX_V_approx
    errors[i] = abs(EX_V_true - EX_V_approx)
  end

  # @show eps
  # @show errors

  foo = UP.lineplot(eps, errors, xscale=:log10, yscale=:log10)
  UP.lineplot!(foo, eps, eps)
  println(foo)
end

function test_DE(N::Int, M::Int, m::Int; benchmark::Bool=true)
  X = rand(N + M, m)
  Y = rand(N, M)

  tmp_W = zeros(N, M)

  ∇E_loop = zeros(N + M, m)
  ∇E = zeros(N + M, m)

  DE_loop!!(∇E_loop, tmp_W, X, Y)
  DE!!(∇E, tmp_W, X, Y)

  @show norm(∇E_loop - ∇E)

  if benchmark
    @info "Running benchmarks..., this may take a while"
    show(stdout, "text/plain", BT.@benchmark DE_loop!!($∇E_loop, $tmp_W, $X, $Y))
    println()
    show(stdout, "text/plain", BT.@benchmark DE!!($∇E, $tmp_W, $X, $Y))
  end
end

function benchmark()
  slabs, _, _ = load_slabs(T=Float64)
  Y::Matrix{Float64} = hcat([vec(slab.data) for slab in slabs]...)
  @show size(Y)

  N::Int, M::Int = size(Y)
  m::Int = 2

  X::Vector{Float64} = fill(0.5, (N + M) * m)
  ∇E::Vector{Float64} = zeros((N + M) * m)
  tmp = zeros(size(Y))

  show(stdout, "text/plain", BT.@benchmark DE_loop!!(reshape($∇E, $N + $M, $m), $tmp, reshape($X, $N + $M, $m), reshape($Y, $N, $M)))
  println()
  show(stdout, "text/plain", BT.@benchmark E_loop(reshape($X, $N + $M, $m), reshape($Y, $N, $M)))
end

function plot_result_mixture_1(X::Vector{Float64}, N::Int, M::Int, m::Int)
  X_ = reshape(X, N + M, m)
  λ = view(X_, 1:N, :)
  s = view(X_, N+1:N+M, :)

  @show size(λ)
  @show size(s)

  fig = GLM.Figure()
  axes = map(1:m+1) do i
    aspect = if i < m + 1
      GLM.DataAspect()
    else
      nothing
    end
    GLM.Axis(fig[1, i], aspect=aspect)
  end

  n = Int(sqrt(N))

  # Component density
  GLM.image!(axes[1], reshape(view(λ, :, 1), n, n))
  GLM.image!(axes[2], reshape(view(λ, :, 2), n, n))

  # Spectra
  GLM.lines!(axes[3], s[:, 1])
  GLM.lines!(axes[3], s[:, 2])

  @show norm(λ[:, 1] - λ[:, 2])
  @show norm(s[:, 1] - s[:, 2])

  display(fig)
end

function optim(algo::Symbol=:LD_MMA)
  slabs, _, _ = load_slabs(T=Float64)
  Y::Matrix{Float64} = hcat([vec(slab.data) for slab in slabs]...)
  @show size(Y)

  N::Int, M::Int = size(Y)
  m::Int = 2

  # Initial choice of X
  # it seems that:
  # * ∇E(0) = 0
  # X::Vector{Float64} = zeros((N + M) * m)
  # * choosing X = 0.5 and BFGS yields a relatively quick convergence to two identical components
  # X::Vector{Float64} = fill(0.5, (N + M) * m)
  X::Vector{Float64} = 0.5 .+ 0.1 * rand((N + M) * m)
  ∇E::Vector{Float64} = zeros((N + M) * m)
  tmp = zeros(size(Y))

  function objective(X::Vector{Float64}, grad::Vector{Float64})
    if length(grad) > 0
      DE!!(reshape(grad, N + M, m), tmp, reshape(X, N + M, m), reshape(Y, N, M))
    else
      @debug "No gradient requested!"
    end
    # @show "|∇E| = $(norm(grad))"
    max_Σ_λ = maximum(sum(view(reshape(X, N + M, m), 1:N, :); dims=2))
    value = E!(reshape(X, N + M, m), reshape(Y, N, M), tmp)
    @info "E = $value, |∇E| = $(norm(grad)), max_Σ_λ = $max_Σ_λ"
    return value
  end

  opt = NLopt.Opt(algo, (N + M) * m)
  NLopt.lower_bounds!(opt, fill(0.0, (N + M) * m))
  NLopt.upper_bounds!(opt, vec([fill(1.0, N, m); fill(Inf, M, m)]))
  NLopt.min_objective!(opt, objective)

  res = NLopt.optimize(opt, X)

  @show opt

  return res, opt
end


end # module

# possible algorithms from NLopt
#    LD_LBFGS_NOCEDAL
#    LD_LBFGS
#    LD_VAR1
#    LD_VAR2
#    LD_TNEWTON
#    LD_TNEWTON_RESTART
#    LD_TNEWTON_PRECOND
#    LD_TNEWTON_PRECOND_RESTART
#    LD_MMA
#    LD_AUGLAG
#    LD_AUGLAG_EQ
#    LD_SLSQP
#    LD_CCSAQ

res, opt = OptimMixture.optim(:LD_LBFGS);
# res, opt = OptimMixture.optim(:LD_TNEWTON)
OptimMixture.plot_result_mixture_1(res[2], 512 * 512, 32, 2)
# OptimMixture.benchmark();
# OptimMixture.test_E(512 * 512, 32, 2)
# OptimMixture.test_DE(512 * 512, 32, 2)
# OptimMixture.test_Q(512 * 512, 32, 2)
# OptimMixture.check_derivative_E(512 * 512, 32, 2)
# OptimMixture.check_derivative_E(512 * 512, 32, 2; loop=true)

# vim: ts=2:sw=2:sts=2