param(
    [Parameter(Mandatory = $true)]
    [string]$Source,

    [string]$Output = (Join-Path $PSScriptRoot '..\artifacts\requirements-source-inventory.md')
)

$ErrorActionPreference = 'Stop'

Add-Type -AssemblyName System.IO.Compression.FileSystem

$sourcePath = (Resolve-Path -LiteralPath $Source).Path
$outputPath = [System.IO.Path]::GetFullPath($Output)
$outputDirectory = Split-Path -Parent $outputPath
if (-not (Test-Path -LiteralPath $outputDirectory)) {
    New-Item -ItemType Directory -Path $outputDirectory | Out-Null
}

$stylesByID = @{}
$archive = [System.IO.Compression.ZipFile]::OpenRead($sourcePath)
try {
    $entry = $archive.GetEntry('word/document.xml')
    if ($null -eq $entry) {
        throw 'DOCX中缺少word/document.xml'
    }
    $stream = $entry.Open()
    try {
        $reader = [System.IO.StreamReader]::new($stream, [System.Text.Encoding]::UTF8, $true)
        try {
            [xml]$document = $reader.ReadToEnd()
        }
        finally {
            $reader.Dispose()
        }
    }
    finally {
        $stream.Dispose()
    }

    $stylesEntry = $archive.GetEntry('word/styles.xml')
    if ($null -ne $stylesEntry) {
        $stylesStream = $stylesEntry.Open()
        try {
            $stylesReader = [System.IO.StreamReader]::new($stylesStream, [System.Text.Encoding]::UTF8, $true)
            try {
                [xml]$stylesDocument = $stylesReader.ReadToEnd()
            }
            finally {
                $stylesReader.Dispose()
            }
        }
        finally {
            $stylesStream.Dispose()
        }
        $stylesNamespace = [System.Xml.XmlNamespaceManager]::new($stylesDocument.NameTable)
        $stylesNamespace.AddNamespace('w', 'http://schemas.openxmlformats.org/wordprocessingml/2006/main')
        foreach ($styleNode in $stylesDocument.SelectNodes('/w:styles/w:style', $stylesNamespace)) {
            $idAttribute = $styleNode.Attributes.GetNamedItem('styleId', 'http://schemas.openxmlformats.org/wordprocessingml/2006/main')
            $nameNode = $styleNode.SelectSingleNode('./w:name', $stylesNamespace)
            if ($null -eq $idAttribute -or $null -eq $nameNode) {
                continue
            }
            $nameAttribute = $nameNode.Attributes.GetNamedItem('val', 'http://schemas.openxmlformats.org/wordprocessingml/2006/main')
            if ($null -ne $nameAttribute) {
                $stylesByID[$idAttribute.Value] = $nameAttribute.Value
            }
        }
    }
}
finally {
    $archive.Dispose()
}

$namespace = [System.Xml.XmlNamespaceManager]::new($document.NameTable)
$namespace.AddNamespace('w', 'http://schemas.openxmlformats.org/wordprocessingml/2006/main')
$paragraphs = $document.SelectNodes('/w:document/w:body/w:p', $namespace)
if ($paragraphs.Count -eq 0) {
    throw 'DOCX正文没有可追踪段落'
}

$hash = (Get-FileHash -LiteralPath $sourcePath -Algorithm SHA256).Hash.ToLowerInvariant()
$lines = [System.Collections.Generic.List[string]]::new()
$lines.Add('# 原始需求来源段落清单')
$lines.Add('')
$lines.Add('> 此文件由`scripts/extract-requirements.ps1`从原始DOCX机械提取，用于稳定引用来源，不替代原需求文档。`Pxxxx`是`word/document.xml`正文段落的零基顺序号；空段落保留编号但不输出正文。')
$lines.Add('')
$lines.Add("- 来源文件：$([System.IO.Path]::GetFileName($sourcePath))")
$lines.Add(('- SHA-256：`{0}`' -f $hash))
$lines.Add("- 正文段落总数：$($paragraphs.Count)")
$lines.Add('')
$lines.Add('## 非空段落')
$lines.Add('')

$nonEmpty = 0
for ($index = 0; $index -lt $paragraphs.Count; $index++) {
    $paragraph = $paragraphs[$index]
    $textParts = $paragraph.SelectNodes('.//w:t', $namespace) | ForEach-Object { $_.InnerText }
    $text = (($textParts -join '') -replace '[\r\n\t]+', ' ' -replace '\s{2,}', ' ').Trim()
    if ([string]::IsNullOrWhiteSpace($text)) {
        continue
    }
    $nonEmpty++
    $styleNode = $paragraph.SelectSingleNode('./w:pPr/w:pStyle', $namespace)
    $style = 'Normal'
    if ($null -ne $styleNode) {
        $styleAttribute = $styleNode.Attributes.GetNamedItem('val', 'http://schemas.openxmlformats.org/wordprocessingml/2006/main')
        if ($null -ne $styleAttribute -and -not [string]::IsNullOrWhiteSpace($styleAttribute.Value)) {
            $style = $styleAttribute.Value
            if ($stylesByID.ContainsKey($style)) {
                $style = $stylesByID[$style]
            }
        }
    }
    $safeText = $text.Replace('\', '\\').Replace('`', '\`')
    $lines.Add(('- `P{0}` [{1}] {2}' -f $index.ToString('0000'), $style, $safeText))
}

$lines.Insert(7, "- 非空段落数：$nonEmpty")
[System.IO.File]::WriteAllLines($outputPath, $lines, [System.Text.UTF8Encoding]::new($false))

Write-Output "已提取 $nonEmpty/$($paragraphs.Count) 个段落：$outputPath"