. $PSScriptRoot\..\..\Load-PesterModules.ps1
$here = Split-Path -Parent $MyInvocation.MyCommand.Path
$sut = (Split-Path -Leaf $MyInvocation.MyCommand.Path) -replace '\.tests\.', '.'
$functionPath = Join-Path -Path $here -ChildPath $sut
Write-Host "Overriding SUT: $functionPath"
Import-Module $functionPath -Force
$moduleForMock = ''

Describe 'Get-FolderSizeMb' {

    $testSize = 1024 * 1024
    $testPath = 'TestDrive:\Test'
    $testServer = 'server1.test.local'

    Mock -CommandName Test-Path -ModuleName $moduleForMock -MockWith { return $true }
    Mock -CommandName Get-ChildItem -ModuleName $moduleForMock -MockWith { return @(@{Length = $testSize }) }
    Mock -CommandName Measure-Object -ModuleName $moduleForMock -MockWith { return @{Sum = $testSize } }
    Mock -CommandName Compare-StringToLocalMachineIdentifiers -ModuleName $moduleForMock -MockWith { return $true }
    Mock -CommandName Test-StringIsNullOrWhitespace -ModuleName $moduleForMock -MockWith { return $true }

    Mock -CommandName Invoke-Command -ModuleName $moduleForMock -MockWith {
        return $ScriptBlock.Invoke(@($testPath))
    }

    Context 'Input Validation' {

        It 'Throws if Path is null' {

            { Get-FolderSizeMb -Path $null } | Should -Throw
        }

        It 'Throws if Path is empty' {

            { Get-FolderSizeMb -Path '' } | Should -Throw
        }
    }

    Context 'Logic' {

        It 'Performs command on localhost by default' {

            Get-FolderSizeMb -Path $testPath | Out-Null

            Assert-MockCalled -ModuleName $moduleForMock -CommandName Test-StringIsNullOrWhitespace -Times 1 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Compare-StringToLocalMachineIdentifiers -Times 0 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Test-Path -Times 1 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Get-ChildItem -Times 1 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Measure-Object -Times 1 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Invoke-Command -Times 1 -Exactly -Scope It `
                -ParameterFilter { ( -not $PSBoundParameters.ContainsKey('ComputerName')) }
        }

        It 'Performs command on localhost if ComputerName matches current server' {

            Mock -CommandName Test-StringIsNullOrWhitespace -ModuleName $moduleForMock -MockWith { return $false }

            Get-FolderSizeMb -Path $testPath -ComputerName $testServer | Out-Null

            Assert-MockCalled -ModuleName $moduleForMock -CommandName Test-StringIsNullOrWhitespace -Times 1 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Compare-StringToLocalMachineIdentifiers -Times 1 -Exactly -Scope It `
                -ParameterFilter { $stringToCheck -eq $testServer }
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Invoke-Command -Times 1 -Exactly -Scope It `
                -ParameterFilter { ( -not $PSBoundParameters.ContainsKey('ComputerName')) }

            Mock -CommandName Test-StringIsNullOrWhitespace -ModuleName $moduleForMock -MockWith { return $true }
        }

        It 'Performs command on remote server if ComputerName does not match current server' {

            Mock -CommandName Test-StringIsNullOrWhitespace -ModuleName $moduleForMock -MockWith { return $false }
            Mock -CommandName Compare-StringToLocalMachineIdentifiers -ModuleName $moduleForMock -MockWith { return $false }

            $testServer2 = 'server2.test.local'

            Get-FolderSizeMb -Path $testPath -ComputerName $testServer2 | Out-Null

            Assert-MockCalled -ModuleName $moduleForMock -CommandName Test-StringIsNullOrWhitespace -Times 1 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Compare-StringToLocalMachineIdentifiers -Times 1 -Exactly -Scope It `
                -ParameterFilter { $stringToCheck -eq $testServer2 }
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Invoke-Command -Times 1 -Exactly -Scope It `
                -ParameterFilter { $ComputerName -eq $testServer2 }

            Mock -CommandName Test-StringIsNullOrWhitespace -ModuleName $moduleForMock -MockWith { return $true }
            Mock -CommandName Compare-StringToLocalMachineIdentifiers -ModuleName $moduleForMock -MockWith { return $true }
        }

        It 'Returns zero if path not found' {

            Mock -CommandName Test-Path -ModuleName $moduleForMock -MockWith { return $false }

            $result = Get-FolderSizeMb -Path $testPath
            $result | Should -BeExactly 0

            Assert-MockCalled -ModuleName $moduleForMock -CommandName Test-Path -Times 1 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Get-ChildItem -Times 0 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Measure-Object -Times 0 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Invoke-Command -Times 1 -Exactly -Scope It

            Mock -CommandName Test-Path -ModuleName $moduleForMock -MockWith { return $true }
        }

        It 'Returns size in MB if path is found' {

            $result = Get-FolderSizeMb -Path $testPath
            $result | Should -BeExactly ($testSize / 1Mb)

            Assert-MockCalled -ModuleName $moduleForMock -CommandName Test-Path -Times 1 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Get-ChildItem -Times 1 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Measure-Object -Times 1 -Exactly -Scope It
            Assert-MockCalled -ModuleName $moduleForMock -CommandName Invoke-Command -Times 1 -Exactly -Scope It
        }
    }
}