#Requires -Modules @{ ModuleName = 'Pester'; ModuleVersion = '5.0.0' }

<#
    SC-005: every write body has exactly one key, equal to engine.targetAttribute.

    This is the assertion that bounds the blast radius. OTD-003 records that Graph
    application permissions have no per-property scope: whatever this engine can write
    to the persona attribute, it could equally write to any other user property. The
    directory will not stop a body with a second key, so this test is the thing that
    does.
#>

BeforeAll {
    $repoRoot = Split-Path (Split-Path $PSScriptRoot -Parent) -Parent
    . (Join-Path $repoRoot 'tests/TestHelpers.ps1')
    foreach ($file in (Get-PersonaSourceFile -RepoRoot $repoRoot)) { . $file }

    $script:target = 'extension_<EXTENSION-APP-ID>_<PERSONA>'
    $script:approved = @($script:target)
}

Describe 'Write body construction (SC-005)' -Tag 'Safety' {

    It 'produces a body with exactly one key' {
        $body = New-PersonaWriteBody -AttributeName $target -Value 'Employee' `
            -TargetAttribute $target -ApprovedWritableAttributes $approved

        $body.Count | Should -Be 1
    }

    It 'names that key exactly the target attribute' {
        $body = New-PersonaWriteBody -AttributeName $target -Value 'Employee' `
            -TargetAttribute $target -ApprovedWritableAttributes $approved

        @($body.Keys)[0] | Should -BeExactly $target
    }

    It 'carries the calculated value unchanged' {
        $body = New-PersonaWriteBody -AttributeName $target -Value 'Tier0-Admin' `
            -TargetAttribute $target -ApprovedWritableAttributes $approved

        $body[$target] | Should -BeExactly 'Tier0-Admin'
    }

    It 'permits an empty value, which clears the attribute' {
        # Clearing is a legitimate outcome when a rule set stops matching an account.
        # It must go through the same single-key path as any other write.
        $body = New-PersonaWriteBody -AttributeName $target -Value '' `
            -TargetAttribute $target -ApprovedWritableAttributes $approved

        $body.Count | Should -Be 1
        $body[$target] | Should -Be ''
    }
}

Describe 'Every body issued during a run has exactly one key' -Tag 'Safety' {

    It 'holds across a full enforcing population' {
        # The unit test above proves the builder is correct. This proves the run loop
        # actually uses it, on every account, with no other path to a PATCH.
        $script:captured = [System.Collections.Generic.List[object]]::new()

        Mock Write-Host { }
        Mock Get-PersonaUsers { @(New-TestPopulation -Count 20 -TargetAttribute $script:target) }
        Mock Invoke-PersonaGraphRequest {
            if ($Method -eq 'PATCH') { $script:captured.Add($Body) }
            @{}
        }

        $outcome = Invoke-PersonaEngineRun `
            -Configuration (New-TestRuntimeConfiguration -TargetAttribute $script:target) `
            -TargetAttribute $script:target -Context (New-TestAuditContext -Mode 'Enforce') `
            -IsEnforcing -ShouldProcessGate { param($t, $d) $true }

        $script:captured.Count | Should -BeGreaterThan 0
        $script:captured.Count | Should -Be $outcome.Counters.Updated

        foreach ($body in $script:captured) {
            $body.Count | Should -Be 1
            @($body.Keys)[0] | Should -BeExactly $script:target
        }
    }

    It 'issues a PATCH and nothing else as a write method' {
        $script:methods = [System.Collections.Generic.List[string]]::new()

        Mock Write-Host { }
        Mock Get-PersonaUsers { @(New-TestPopulation -Count 10 -TargetAttribute $script:target) }
        Mock Invoke-PersonaGraphRequest {
            $script:methods.Add($Method)
            @{}
        }

        $null = Invoke-PersonaEngineRun `
            -Configuration (New-TestRuntimeConfiguration -TargetAttribute $script:target) `
            -TargetAttribute $script:target -Context (New-TestAuditContext -Mode 'Enforce') `
            -IsEnforcing -ShouldProcessGate { param($t, $d) $true }

        # No PUT and no DELETE: a PUT would replace the whole user object, and there
        # is no circumstance in which this engine removes one.
        $script:methods | Should -Not -Contain 'PUT'
        $script:methods | Should -Not -Contain 'DELETE'
        $script:methods | Should -Not -Contain 'POST'
        $script:methods | Should -Contain 'PATCH'
    }
}

Describe 'New-PersonaWriteBody is the only construction path' -Tag 'Safety' {

    It 'is the only source file that builds a PATCH body' {
        # A second construction site would make SC-005 a property of a convention
        # rather than of a testable function.
        $sources = Get-ChildItem -Path (Join-Path $repoRoot 'src') -Filter '*.ps1' -Recurse -File

        $offenders = foreach ($file in $sources) {
            if ($file.Name -eq 'New-PersonaWriteBody.ps1') { continue }

            $text = Get-Content -LiteralPath $file.FullName -Raw
            if ($text -match "Method\s*=?\s*'PATCH'" -and $text -notmatch 'New-PersonaWriteBody') {
                # Invoke-PersonaGraphRequest declares PATCH in a ValidateSet; it does
                # not construct a body.
                if ($file.Name -ne 'Invoke-PersonaGraphRequest.ps1') { $file.Name }
            }
        }

        $offenders | Should -BeNullOrEmpty
    }
}