# frozen_string_literal: true

require 'spec_helper'

# Simple examples taken from: https://blog.scottlogic.com/2018/04/26/webassembly-by-hand.html

RSpec.describe 'WAT code generation' do
  let(:mod) { WAG::Module.new }
  subject { mod }

  context 'Basic example' do
    let(:mod) do
      super().tap do |mod|
        mod.func do
          result(:i32)
          i32.const(42)
        end
        mod.export('helloWorld') do
          func(0)
        end
      end
    end

    describe '#to_wat' do
      subject { mod.to_wat.to_s }
      it { is_expected.to eq '(module (export "helloWorld" (func 0)) (func (result i32) (i32.const 42)))' }
    end

    describe '#to_wasm' do
      subject { mod.to_wasm }

      it { is_expected.to be_valid }
    end
  end

  context 'Game of life example' do
    let(:mod) do
      super().tap do |mod|
        mod.import('console', 'log') do
          func(:log) do
            param(:i32)
            param(:i32)
          end
        end

        mod.memory(:mem, 1)

        mod.table(16, :anyfunc)

        mod.elem(0, :dead, :dead, :dead, :alive, :dead, :dead, :dead, :dead,
                 :dead, :dead, :dead, :alive, :alive, :dead, :dead, :dead,
                 :dead, :dead)

        mod.func(:alive) do
          result(:i32)
          i32.const(1)
        end

        mod.func(:dead) do
          result(:i32)
          i32.const(0)
        end

        mod.func(:offsetFromCoordinate) do
          param(:x, :i32)
          param(:y, :i32)
          result(:i32)

          i32.add do
            i32.mul do
              i32.const(200)
              local.get(:y)
            end
            i32.mul do
              i32.const(4)
              local.get(:x)
            end
          end
        end

        mod.func(:setCell) do
          param(:x, :i32)
          param(:y, :i32)
          param(:value, :i32)

          i32.store do
            call(:offsetFromCoordinate) do
              local.get(:x)
              local.get(:y)
            end
            local.get(:value)
          end
        end

        mod.func(:getCell) do
          param(:x, :i32)
          param(:y, :i32)
          result(:i32)

          if_ do
            result(:i32)
            block do
              result(:i32)
              i32.and do
                call(:inRange) do
                  i32.const(0)
                  i32.const(50)
                  local.get(:x)
                end
                call(:inRange) do
                  i32.const(0)
                  i32.const(50)
                  local.get(:y)
                end
              end
            end
            then_ do
              i32.load8_u do
                call(:offsetFromCoordinate) do
                  local.get(:x)
                  local.get(:y)
                end
              end
            end
            else_ do
              i32.const(0)
            end
          end
        end

        mod.func(:liveNeighbourCount) do
          param(:x, :i32)
          param(:y, :i32)
          result(:i32)

          i32.const(0)

          # add the cell value from x + 1, y
          call(:isCellAlive) do
            i32.add do
              local.get(:x)
              i32.const(1)
            end
            local.get(:y)
          end
          i32.add

          # add the cell value from x - 1, y
          call(:isCellAlive) do
            i32.add do
              local.get(:x)
              i32.const(-1)
            end
            local.get(:y)
          end
          i32.add

          # add the cell value from x, y - 1
          call(:isCellAlive) do
            local.get(:x)
            i32.add do
              local.get(:y)
              i32.const(-1)
            end
          end
          i32.add

          # add the cell value from x - 1, y - 1
          call(:isCellAlive) do
            i32.add do
              local.get(:x)
              i32.const(-1)
            end
            i32.add do
              local.get(:y)
              i32.const(-1)
            end
          end
          i32.add

          # add the cell value from x + 1, y - 1
          call(:isCellAlive) do
            i32.add do
              local.get(:x)
              i32.const(1)
            end
            i32.add do
              local.get(:y)
              i32.const(-1)
            end
          end
          i32.add

          # add the cell value from x, y + 1
          call(:isCellAlive) do
            local.get(:x)
            i32.add do
              local.get(:y)
              i32.const(1)
            end
          end
          i32.add

          # add the cell value from x - 1, y + 1
          call(:isCellAlive) do
            i32.add do
              local.get(:x)
              i32.const(-1)
            end
            i32.add do
              local.get(:y)
              i32.const(1)
            end
          end
          i32.add

          # add the cell value from x + 1, y + 1
          call(:isCellAlive) do
            i32.add do
              local.get(:x)
              i32.const(1)
            end
            i32.add do
              local.get(:y)
              i32.const(1)
            end
          end
          i32.add
        end

        mod.func(:inRange) do
          param(:low, :i32)
          param(:high, :i32)
          param(:value, :i32)
          result(:i32)

          i32.and do
            i32.ge_s do
              local.get(:value)
              local.get(:low)
            end
            i32.lt_s do
              local.get(:value)
              local.get(:high)
            end
          end
        end

        mod.func(:isCellAlive) do
          param(:x, :i32)
          param(:y, :i32)
          result(:i32)

          i32.and do
            call(:getCell) do
              local.get(:x)
              local.get(:y)
            end
            i32.const(1)
          end
        end

        mod.func(:setCellStateForNextGeneration) do
          param(:x, :i32)
          param(:y, :i32)
          param(:value, :i32)

          call(:setCell) do
            local.get(:x)
            local.get(:y)
            i32.or do
              call(:isCellAlive) do
                local.get(:x)
                local.get(:y)
              end
              i32.shl do
                local.get(:value)
                i32.const(1)
              end
            end
          end
        end

        mod.func(:evolveCellToNextGeneration) do
          param(:x, :i32)
          param(:y, :i32)

          call(:setCellStateForNextGeneration) do
            local.get(:x)
            local.get(:y)
            call_indirect do
              result(:i32)
              i32.or do
                i32.mul do
                  i32.const(9)
                  call(:isCellAlive) do
                    local.get(:x)
                    local.get(:y)
                  end
                end
                call(:liveNeighbourCount) do
                  local.get(:x)
                  local.get(:y)
                end
              end
            end
          end
        end

        mod.func(:increment) do
          param(:value, :i32)
          result(:i32)

          i32.add do
            local.get(:value)
            i32.const(1)
          end
        end

        mod.func(:evolveAllCells) do
          local(:x, :i32)
          local(:y, :i32)

          local.set(:x) do
            i32.const(0)
          end
          local.set(:y) do
            i32.const(0)
          end

          block do
            loop_ do
              local.set(:x) do
                i32.const(0)
              end

              block do
                loop_ do
                  call(:evolveCellToNextGeneration) do
                    local.get(:x)
                    local.get(:y)
                  end
                  local.set(:x) do
                    call(:increment) do
                      local.get(:x)
                    end
                  end
                  br_if(1) do
                    i32.eq do
                      local.get(:x)
                      i32.const(50)
                    end
                  end
                  br(0)
                end
              end

              local.set(:y) do
                call(:increment) do
                  local.get(:y)
                end
              end
              br_if(1) do
                i32.eq do
                  local.get(:y)
                  i32.const(50)
                end
              end
              br(0)
            end
          end
        end

        mod.func(:promoteNextGeneration) do
          local(:x, :i32)
          local(:y, :i32)

          local.set(:x) do
            i32.const(0)
          end
          local.set(:y) do
            i32.const(0)
          end

          block do
            loop_ do
              local.set(:x) do
                i32.const(0)
              end

              block do
                loop_ do
                  call(:setCell) do
                    local.get(:x)
                    local.get(:y)
                    i32.shr_u do
                      call(:getCell) do
                        local.get(:x)
                        local.get(:y)
                      end
                      i32.const(1)
                    end
                  end

                  local.set(:x) do
                    call(:increment) do
                      local.get(:x)
                    end
                  end
                  br_if(1) do
                    i32.eq do
                      local.get(:x)
                      i32.const(50)
                    end
                  end
                  br(0)
                end
              end

              local.set(:y) do
                call(:increment) do
                  local.get(:y)
                end
              end
              br_if(1) do
                i32.eq do
                  local.get(:y)
                  i32.const(50)
                end
              end
              br(0)
            end
          end
        end

        mod.func(:tick) do
          call(:evolveAllCells)
          call(:promoteNextGeneration)
        end

        mod.export('tick') do
          func(:tick)
        end
        mod.export('promoteNextGeneration') do
          func(:promoteNextGeneration)
        end
        mod.export('evolveAllCells') do
          func(:evolveAllCells)
        end
        mod.export('evolveCellToNextGeneration') do
          func(:evolveCellToNextGeneration)
        end
        mod.export('setCellStateForNextGeneration') do
          func(:setCellStateForNextGeneration)
        end
        mod.export('isCellAlive') do
          func(:isCellAlive)
        end
        mod.export('inRange') do
          func(:inRange)
        end
        mod.export('offsetFromCoordinate') do
          func(:offsetFromCoordinate)
        end
        mod.export('liveNeighbourCount') do
          func(:liveNeighbourCount)
        end
        mod.export('getCell') do
          func(:getCell)
        end
        mod.export('setCell') do
          func(:setCell)
        end
        mod.export('memory') do
          memory(:mem)
        end
      end
    end

    describe '#to_wasm' do
      subject { mod.to_wasm }
      it { is_expected.to be_valid }
    end
  end
end