#!/usr/bin/env pwsh
#
# Business Central Data Export via BC API v2.0
# Authenticates to Azure AD and extracts critical business data as JSON
#

param(
    [Parameter(Mandatory=$true)]
    [string]$OutputPath,
    [string]$SinceDateTime = ""  # ISO 8601, e.g. "2026-02-15T00:00:00Z" for incremental
)

# Get configuration from environment variables
$tenantId = $env:AZURE_TENANT_ID
$clientId = $env:AZURE_CLIENT_ID
$clientSecret = $env:AZURE_CLIENT_SECRET
$environmentName = $env:BC_ENVIRONMENT_NAME
$bcCompanyName = $env:BC_COMPANY_NAME  # optional: filter to specific company

$baseUrl = "https://api.businesscentral.dynamics.com/v2.0/$tenantId/$environmentName/api/v2.0"

# Standalone entities to extract (support lastModifiedDateTime filter for incremental)
$entities = @(
    "accounts",
    "customers",
    "vendors",
    "items",
    "generalLedgerEntries",
    "bankAccounts",
    "employees",
    "dimensions",
    "dimensionValues",
    "currencies",
    "paymentTerms",
    "paymentMethods",
    "journals",
    "journalLines",
    "countriesRegions",
    "companyInformation",
    "itemCategories",
    "shipmentMethods",
    "taxAreas",
    "taxGroups",
    "unitsOfMeasure",
    "timeRegistrationEntries",
    "contacts",
    "generalProductPostingGroups",
    "inventoryPostingGroups",
    "itemLedgerEntries",
    "opportunities",
    "locations",
    "projects",
    "irs1099"
)

# Financial report entities (always full export, no incremental filter support)
$reportEntities = @(
    "agedAccountsPayable",
    "agedAccountsReceivable",
    "balanceSheet",
    "cashFlowStatement",
    "incomeStatement",
    "retainedEarningsStatement",
    "trialBalance",
    "customerFinancialDetails",
    "customerSales",
    "vendorPurchases"
)

# Document entities with line items
# Lines cannot be queried standalone at the top level.
# We fetch document headers first, then fetch lines per document.
$documentEntities = @{
    "salesInvoices"            = "salesInvoiceLines"
    "salesOrders"              = "salesOrderLines"
    "salesCreditMemos"         = "salesCreditMemoLines"
    "purchaseInvoices"         = "purchaseInvoiceLines"
    "purchaseOrders"           = "purchaseOrderLines"
    "salesQuotes"              = "salesQuoteLines"
    "salesShipments"           = "salesShipmentLines"
    "purchaseReceipts"         = "purchaseReceiptLines"
    "customerPaymentJournals"  = "customerPayments"
    "vendorPaymentJournals"    = "vendorPayments"
}

# Token management
$script:currentToken = $null
$script:tokenExpiry = [datetime]::MinValue

function Write-Log {
    param([string]$Message, [string]$Level = "INFO")
    $timestamp = Get-Date -Format "yyyy-MM-dd HH:mm:ss"
    Write-Host "[$timestamp] [$Level] $Message"
}

function Get-AzureADToken {
    Write-Log "Authenticating to Azure AD..."

    $tokenUrl = "https://login.microsoftonline.com/$tenantId/oauth2/v2.0/token"

    $body = @{
        client_id     = $clientId
        client_secret = $clientSecret
        scope         = "https://api.businesscentral.dynamics.com/.default"
        grant_type    = "client_credentials"
    }

    try {
        $response = Invoke-RestMethod -Uri $tokenUrl -Method Post -Body $body -ContentType "application/x-www-form-urlencoded"
        $script:currentToken = $response.access_token
        # Refresh 5 minutes before actual expiry (tokens typically last 60-90 min)
        $script:tokenExpiry = (Get-Date).AddSeconds($response.expires_in - 300)
        Write-Log "Successfully authenticated (token valid for $($response.expires_in)s)"
        return $script:currentToken
    }
    catch {
        Write-Log "Failed to authenticate: $_" "ERROR"
        throw
    }
}

function Get-ValidToken {
    if ($null -eq $script:currentToken -or (Get-Date) -ge $script:tokenExpiry) {
        Write-Log "Token expired or missing, refreshing..."
        Get-AzureADToken | Out-Null
    }
    return $script:currentToken
}

function Invoke-BCApi {
    param(
        [string]$Url,
        [int]$TimeoutSec = 120,
        [int]$MaxRetries = 10
    )

    for ($attempt = 1; $attempt -le $MaxRetries; $attempt++) {
        $token = Get-ValidToken
        $headers = @{
            "Authorization" = "Bearer $token"
            "Accept"        = "application/json"
        }

        try {
            $response = Invoke-RestMethod -Uri $Url -Method Get -Headers $headers -TimeoutSec $TimeoutSec
            return $response
        }
        catch {
            $statusCode = $null
            $errorBody = ""
            if ($_.Exception.Response) {
                $statusCode = [int]$_.Exception.Response.StatusCode
            }
            if ($_.ErrorDetails.Message) {
                $errorBody = $_.ErrorDetails.Message
            }

            # Log the actual error so we can diagnose issues
            $shortError = if ($errorBody.Length -gt 200) { $errorBody.Substring(0, 200) + "..." } else { $errorBody }
            if (-not $shortError) { $shortError = "$_" }

            # Table lock: BC returns 500 with very specific wording
            $isTableLock = $errorBody -match "transaction done by another session|being updated in a transaction|deadlock victim"
            # Rate limit
            $isThrottled = ($statusCode -eq 429)
            # Timeout
            $isTimeout = ($_ -match "Timeout")
            # Other server errors (500+)
            $isServerError = ($statusCode -ge 500 -and -not $isTableLock)

            $isRetryable = $isTableLock -or $isThrottled -or $isServerError -or $isTimeout

            if ($isRetryable -and $attempt -lt $MaxRetries) {
                if ($isTableLock) {
                    $wait = [math]::Min(30 + ($attempt * 15), 120)
                    Write-Log "    Table lock (attempt $attempt/$MaxRetries), waiting ${wait}s... Error: $shortError" "WARN"
                }
                elseif ($isThrottled) {
                    $wait = [math]::Min(30 * $attempt, 300)
                    Write-Log "    Rate limited (attempt $attempt/$MaxRetries), waiting ${wait}s..." "WARN"
                }
                elseif ($isTimeout) {
                    $wait = [math]::Min(15 * $attempt, 120)
                    Write-Log "    Timeout (attempt $attempt/$MaxRetries), retrying in ${wait}s..." "WARN"
                }
                else {
                    $wait = [math]::Min(15 * $attempt, 120)
                    Write-Log "    HTTP $statusCode (attempt $attempt/$MaxRetries), retrying in ${wait}s... Error: $shortError" "WARN"
                }
                Start-Sleep -Seconds $wait
                continue
            }
            throw
        }
    }
}

function Get-BCData {
    param(
        [string]$Url
    )

    $allRecords = @()
    $currentUrl = $Url

    while ($currentUrl) {
        $response = Invoke-BCApi -Url $currentUrl

        if ($response.value) {
            $allRecords += $response.value
        }

        $currentUrl = $response.'@odata.nextLink'
    }

    return $allRecords
}

function Get-Companies {
    Write-Log "Fetching companies..."
    $companiesUrl = "$baseUrl/companies"
    $companies = Get-BCData -Url $companiesUrl
    Write-Log "Found $($companies.Count) company/companies"
    return $companies
}

function Export-EntityData {
    param(
        [string]$CompanyId,
        [string]$CompanyName,
        [string]$EntityName,
        [string]$OutputDir,
        [switch]$NoFilter
    )

    $entityUrl = "$baseUrl/companies($CompanyId)/$EntityName"
    if ($SinceDateTime -and -not $NoFilter) {
        $entityUrl += "?`$filter=lastModifiedDateTime gt $SinceDateTime"
    }
    $maxEntityRetries = 5

    for ($entityAttempt = 1; $entityAttempt -le $maxEntityRetries; $entityAttempt++) {
        Write-Log "  Exporting $EntityName..."

        try {
            $data = Get-BCData -Url $entityUrl
            $count = 0
            if ($data) { $count = $data.Count }

            $outputFile = Join-Path $OutputDir "$EntityName.json"
            $data | ConvertTo-Json -Depth 10 | Out-File -FilePath $outputFile -Encoding utf8

            Write-Log "  $EntityName : $count records"
            return $count
        }
        catch {
            $errorMsg = "$_"
            $isTableLock = $errorMsg -match "transaction done by another session|being updated in a transaction|deadlock victim"

            if ($isTableLock -and $entityAttempt -lt $maxEntityRetries) {
                $wait = 60 * $entityAttempt
                Write-Log "  Table lock on $EntityName (attempt $entityAttempt/$maxEntityRetries), restarting in ${wait}s..." "WARN"
                Start-Sleep -Seconds $wait
                continue
            }

            Write-Log "  Failed to export ${EntityName}: $errorMsg" "WARN"
            $outputFile = Join-Path $OutputDir "$EntityName.json"
            "[]" | Out-File -FilePath $outputFile -Encoding utf8
            return 0
        }
    }

    return 0
}

function Export-DocumentWithLines {
    param(
        [string]$CompanyId,
        [string]$CompanyName,
        [string]$DocumentEntity,
        [string]$LineEntity,
        [string]$OutputDir
    )

    # Retry the entire entity export if it fails (e.g. table lock on first page)
    $maxEntityRetries = 5

    for ($entityAttempt = 1; $entityAttempt -le $maxEntityRetries; $entityAttempt++) {
        Write-Log "  Exporting $DocumentEntity (headers + lines)..."

        $docFile = Join-Path $OutputDir "$DocumentEntity.jsonl"
        $lineFile = Join-Path $OutputDir "$LineEntity.jsonl"
        [System.IO.File]::WriteAllText($docFile, "")
        [System.IO.File]::WriteAllText($lineFile, "")

        $docCount = 0
        $lineCount = 0
        $failed = $false

        try {
            # Step 1: Fetch document headers page by page (no $expand)
            # BC API default page size is ~100, with @odata.nextLink for more
            $currentUrl = "$baseUrl/companies($CompanyId)/$DocumentEntity"
            if ($SinceDateTime) {
                $currentUrl += "?`$filter=lastModifiedDateTime gt $SinceDateTime"
            }

            while ($currentUrl) {
                $response = Invoke-BCApi -Url $currentUrl

                if (-not $response.value -or $response.value.Count -eq 0) {
                    break
                }

                # Step 2: For each document in this page, fetch its lines
                foreach ($doc in $response.value) {
                    $docCount++
                    $docId = $doc.id

                    # Write document header to disk
                    $jsonLine = $doc | ConvertTo-Json -Depth 10 -Compress
                    [System.IO.File]::AppendAllText($docFile, $jsonLine + "`n")

                    # Fetch lines for this document
                    $linesUrl = "$baseUrl/companies($CompanyId)/$DocumentEntity($docId)/$LineEntity"
                    try {
                        $linesResponse = Invoke-BCApi -Url $linesUrl -TimeoutSec 60
                        if ($linesResponse.value -and $linesResponse.value.Count -gt 0) {
                            foreach ($line in $linesResponse.value) {
                                $lineCount++
                                $lineJson = $line | ConvertTo-Json -Depth 10 -Compress
                                [System.IO.File]::AppendAllText($lineFile, $lineJson + "`n")
                            }

                            # Handle pagination within lines (unlikely but possible)
                            $nextLinesUrl = $linesResponse.'@odata.nextLink'
                            while ($nextLinesUrl) {
                                $moreLinesResponse = Invoke-BCApi -Url $nextLinesUrl -TimeoutSec 60
                                if ($moreLinesResponse.value) {
                                    foreach ($line in $moreLinesResponse.value) {
                                        $lineCount++
                                        $lineJson = $line | ConvertTo-Json -Depth 10 -Compress
                                        [System.IO.File]::AppendAllText($lineFile, $lineJson + "`n")
                                    }
                                }
                                $nextLinesUrl = $moreLinesResponse.'@odata.nextLink'
                            }
                        }
                    }
                    catch {
                        Write-Log "    Warning: failed to fetch lines for $DocumentEntity $docId : $_" "WARN"
                    }

                    # Progress every 100 documents
                    if ($docCount % 100 -eq 0) {
                        Write-Log "    Progress: $docCount documents, $lineCount lines"
                    }
                }

                # Next page of documents
                $currentUrl = $response.'@odata.nextLink'
            }

            Write-Log "  $DocumentEntity : $docCount documents, $lineCount lines (complete)"
            return ($docCount + $lineCount)
        }
        catch {
            $errorMsg = "$_"
            $isTableLock = $errorMsg -match "transaction done by another session|being updated in a transaction|deadlock victim"

            if ($isTableLock -and $entityAttempt -lt $maxEntityRetries) {
                $wait = 60 * $entityAttempt
                Write-Log "  Table lock on $DocumentEntity (attempt $entityAttempt/$maxEntityRetries), restarting in ${wait}s..." "WARN"
                Start-Sleep -Seconds $wait
                continue
            }

            Write-Log "  Failed to export ${DocumentEntity} at doc #$docCount : $errorMsg" "WARN"
            Write-Log "  Partial data saved ($docCount docs, $lineCount lines)" "WARN"
            return ($docCount + $lineCount)
        }
    }

    return 0
}

# Main execution
try {
    $exportMode = if ($SinceDateTime) { "incremental" } else { "full" }

    Write-Log "========================================="
    Write-Log "BC Data Export Script (API v2.0)"
    Write-Log "========================================="
    Write-Log "Environment: $environmentName"
    Write-Log "Mode: $exportMode"
    if ($SinceDateTime) {
        Write-Log "Changes since: $SinceDateTime"
    }
    Write-Log "Output Path: $OutputPath"
    $totalEntityCount = $entities.Count + $reportEntities.Count + $documentEntities.Count
    Write-Log "Entities to extract: $totalEntityCount ($($entities.Count) standalone, $($reportEntities.Count) reports, $($documentEntities.Count) with line items)"

    # Create output directory
    $exportDir = $OutputPath
    if (-not (Test-Path $exportDir)) {
        New-Item -ItemType Directory -Path $exportDir -Force | Out-Null
    }

    # Step 1: Get Azure AD token
    Get-AzureADToken | Out-Null

    # Step 2: Get companies
    $companies = Get-Companies

    if ($companies.Count -eq 0) {
        Write-Log "No companies found in environment $environmentName" "ERROR"
        exit 1
    }

    # Save companies list
    $companies | ConvertTo-Json -Depth 10 | Out-File -FilePath (Join-Path $exportDir "companies.json") -Encoding utf8

    # Filter to specific company if configured
    $targetCompanies = $companies
    if ($bcCompanyName) {
        $targetCompanies = $companies | Where-Object { $_.name -eq $bcCompanyName -or $_.displayName -eq $bcCompanyName }
        if ($targetCompanies.Count -eq 0) {
            Write-Log "Company '$bcCompanyName' not found. Available: $($companies.name -join ', ')" "ERROR"
            exit 1
        }
        Write-Log "Filtering to company: $bcCompanyName"
    }

    $totalRecords = 0
    $totalEntities = 0
    $failedEntities = @()

    # Step 3: Export data for each company
    foreach ($company in $targetCompanies) {
        $companyName = $company.name
        $companyId = $company.id

        Write-Log "-----------------------------------------"
        Write-Log "Exporting company: $companyName ($companyId)"

        # Create company directory (sanitize name for filesystem)
        $safeName = $companyName -replace '[\\/:*?"<>|]', '_'
        $companyDir = Join-Path $exportDir $safeName
        if (-not (Test-Path $companyDir)) {
            New-Item -ItemType Directory -Path $companyDir -Force | Out-Null
        }

        # Export standalone entities
        foreach ($entity in $entities) {
            $count = Export-EntityData `
                -CompanyId $companyId `
                -CompanyName $companyName `
                -EntityName $entity `
                -OutputDir $companyDir

            $totalRecords += $count
            $totalEntities++

            if ($count -eq 0) {
                $failedEntities += "$companyName/$entity"
            }
        }

        # Export financial report entities (always full, no incremental filter)
        foreach ($entity in $reportEntities) {
            $count = Export-EntityData `
                -CompanyId $companyId `
                -CompanyName $companyName `
                -EntityName $entity `
                -OutputDir $companyDir `
                -NoFilter

            $totalRecords += $count
            $totalEntities++

            if ($count -eq 0) {
                $failedEntities += "$companyName/$entity"
            }
        }

        # Export document entities with their line items
        foreach ($docEntity in $documentEntities.Keys) {
            $lineEntity = $documentEntities[$docEntity]

            $count = Export-DocumentWithLines `
                -CompanyId $companyId `
                -CompanyName $companyName `
                -DocumentEntity $docEntity `
                -LineEntity $lineEntity `
                -OutputDir $companyDir

            $totalRecords += $count
            $totalEntities++

            if ($count -eq 0) {
                $failedEntities += "$companyName/$docEntity"
            }
        }
    }

    # Save export metadata
    $metadata = @{
        exportDate       = (Get-Date -Format "yyyy-MM-dd HH:mm:ss UTC" -AsUTC)
        environment      = $environmentName
        mode             = $exportMode
        sinceDateTime    = if ($SinceDateTime) { $SinceDateTime } else { $null }
        companies        = @($targetCompanies | ForEach-Object { $_.name })
        entitiesExported = $totalEntities
        totalRecords     = $totalRecords
        failedEntities   = $failedEntities
    }
    $metadata | ConvertTo-Json -Depth 5 | Out-File -FilePath (Join-Path $exportDir "export-metadata.json") -Encoding utf8

    Write-Log "========================================="
    Write-Log "Export completed"
    Write-Log "Mode: $exportMode"
    Write-Log "Companies: $($targetCompanies.Count)"
    Write-Log "Entities: $totalEntities"
    Write-Log "Total records: $totalRecords"
    if ($failedEntities.Count -gt 0) {
        Write-Log "Failed/empty: $($failedEntities.Count) entities" "WARN"
    }
    Write-Log "========================================="

    # Exit code 2 = success but no records (used by bc-backup.sh to skip empty incrementals)
    if ($totalRecords -eq 0 -and $exportMode -eq "incremental") {
        Write-Log "No changes detected since $SinceDateTime"
        exit 2
    }
    exit 0
}
catch {
    Write-Log "Unexpected error: $_" "ERROR"
    Write-Log "Stack trace: $($_.ScriptStackTrace)" "ERROR"
    exit 1
}