param(
    [string]$RepoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
)

$ErrorActionPreference = "Stop"

$sourceDir = Join-Path $RepoRoot "data/tsl_reference_catalog_source"
$outputDir = Join-Path $RepoRoot "docs/tsl/reference/catalog"

$moduleOrder = @(
    [pscustomobject]@{ File = "base";             Summary = "字符串、数组、日期时间、类型转换与常用基础能力" }
    [pscustomobject]@{ File = "math";             Summary = "数值计算、统计分析、矩阵处理与数学算法" }
    [pscustomobject]@{ File = "system";           Summary = "数据类型、表达式调用、性能与运行时能力" }
    [pscustomobject]@{ File = "resource";         Summary = "文件、数据库、网络与外部资源访问" }
    [pscustomobject]@{ File = "platform";         Summary = "平台相关功能与系统接口" }
    [pscustomobject]@{ File = "client";           Summary = "客户端交互、界面控制与前端协作能力" }
    [pscustomobject]@{ File = "graphics";         Summary = "图表、绘图与可视化相关函数" }
    [pscustomobject]@{ File = "compression";      Summary = "压缩、解压与归档能力" }
    [pscustomobject]@{ File = "digest_encoding";  Summary = "哈希、摘要、编码与转换能力" }
    [pscustomobject]@{ File = "third_party";      Summary = "第三方库与外部程序交互能力" }
)

function Get-HeadingSections {
    param([string[]]$Lines)

    $sections = @()

    for ($i = 0; $i -lt $Lines.Count; $i++) {
        if ($Lines[$i] -match '^(#{4,7})\s+(.+?)\s*$') {
            $sections += [pscustomobject]@{
                Level = $Matches[1].Length
                Title = $Matches[2].Trim()
                Start = $i
            }
        }
    }

    for ($i = 0; $i -lt $sections.Count; $i++) {
        $nextStart = if ($i + 1 -lt $sections.Count) { $sections[$i + 1].Start } else { $Lines.Count }
        $sections[$i] | Add-Member -NotePropertyName End -NotePropertyValue ($nextStart - 1)
    }

    return $sections
}

function Test-IsFunctionSection {
    param(
        [string]$Title,
        [string[]]$BodyLines
    )

    if ($null -eq $BodyLines -or $BodyLines.Count -eq 0) {
        return $false
    }

    $body = $BodyLines -join "`n"
    $hasStructuredMarkers = (
        $body -match '(^|\n)\s*用途：' -or
        $body -match '(^|\n)\s*参数：' -or
        $body -match '(^|\n)\s*返回：'
    )

    if ($hasStructuredMarkers) {
        return $true
    }

    $looksLikeFunctionName = $Title -match '^[A-Za-z_][A-Za-z0-9_]*$'
    $hasMeaningfulBody = $body -match '\S'

    return (
        $looksLikeFunctionName -and
        $hasMeaningfulBody
    )
}

function Add-FunctionToGroup {
    param(
        [System.Collections.Specialized.OrderedDictionary]$GroupMap,
        [string]$Category,
        [string]$Subcategory,
        [string]$FunctionName
    )

    if ([string]::IsNullOrWhiteSpace($FunctionName)) {
        return
    }

    $categoryName = if ([string]::IsNullOrWhiteSpace($Category)) { "未分类" } else { $Category }
    $groupTitle = if ([string]::IsNullOrWhiteSpace($Subcategory)) {
        $categoryName
    }
    else {
        "{0} / {1}" -f $categoryName, $Subcategory
    }

    if (-not $GroupMap.Contains($groupTitle)) {
        $GroupMap[$groupTitle] = [pscustomobject]@{
            Title       = $groupTitle
            Category    = $categoryName
            Subcategory = $Subcategory
            Functions   = [System.Collections.Generic.List[string]]::new()
        }
    }

    $functionList = $GroupMap[$groupTitle].Functions
    if (-not $functionList.Contains($FunctionName)) {
        $functionList.Add($FunctionName)
    }
}

function Parse-TslFunctionModule {
    param([string]$Path)

    $lines = Get-Content -LiteralPath $Path
    $sections = Get-HeadingSections -Lines $lines
    $moduleTitle = ($sections | Where-Object { $_.Level -eq 4 } | Select-Object -First 1).Title

    if ([string]::IsNullOrWhiteSpace($moduleTitle)) {
        throw "Unable to detect module title in $Path"
    }

    $groupMap = [ordered]@{}
    $currentCategory = $null
    $currentSubcategory = $null

    foreach ($section in $sections | Where-Object { $_.Level -ge 5 }) {
        $title = $section.Title.Trim()
        if ($title -in @("内容", "范例")) {
            continue
        }

        $bodyLines = @()
        if ($section.End -gt $section.Start) {
            $bodyLines = $lines[($section.Start + 1)..$section.End]
        }

        $isFunction = Test-IsFunctionSection -Title $title -BodyLines $bodyLines

        switch ($section.Level) {
            5 {
                if ($isFunction) {
                    Add-FunctionToGroup -GroupMap $groupMap -Category "直接函数" -Subcategory $null -FunctionName $title
                }
                else {
                    $currentCategory = $title
                    $currentSubcategory = $null
                }
                continue
            }
            6 {
                if ($isFunction) {
                    Add-FunctionToGroup -GroupMap $groupMap -Category $currentCategory -Subcategory $null -FunctionName $title
                }
                else {
                    $currentSubcategory = $title
                }
                continue
            }
            7 {
                if ($isFunction) {
                    Add-FunctionToGroup -GroupMap $groupMap -Category $currentCategory -Subcategory $currentSubcategory -FunctionName $title
                }
                continue
            }
        }
    }

    $groups = foreach ($entry in $groupMap.GetEnumerator()) {
        [pscustomobject]@{
            Title       = $entry.Value.Title
            Category    = $entry.Value.Category
            Subcategory = $entry.Value.Subcategory
            Functions   = @($entry.Value.Functions)
        }
    }

    $functionCount = ($groups | ForEach-Object { $_.Functions } | Sort-Object -Unique).Count

    return [pscustomobject]@{
        File          = [System.IO.Path]::GetFileNameWithoutExtension($Path)
        ModuleTitle   = $moduleTitle
        Groups        = $groups
        FunctionCount = $functionCount
    }
}

function New-MarkdownModulePage {
    param(
        [pscustomobject]$Module,
        [string]$Summary
    )

    $lines = [System.Collections.Generic.List[string]]::new()
    $lines.Add("# $($Module.ModuleTitle)")
    $lines.Add("")
    $lines.Add("这一页只负责函数定位：先按主题找到模块，再在页内搜索函数名。")
    $lines.Add("")
    $lines.Add("## 使用方式")
    $lines.Add("")
    $lines.Add("- 返回总目录：[catalog/index.md](index.md)")
    $lines.Add("- 需要基础语法时回到 [../../syntax/index.md](../../syntax/index.md)")
    $lines.Add("- 需要金融任务组织方式时回到 [../../finance/index.md](../../finance/index.md)")
    $lines.Add("")
    $lines.Add("## 模块范围")
    $lines.Add("")
    $lines.Add("- 说明：$Summary")
    $lines.Add("- 主题数：$($Module.Groups.Count)")
    $lines.Add("- 函数数：$($Module.FunctionCount)")
    $lines.Add("")
    $lines.Add("## 主题目录")
    $lines.Add("")

    foreach ($group in $Module.Groups) {
        $lines.Add("### $($group.Title)")
        $lines.Add("")
        foreach ($functionName in $group.Functions) {
            $lines.Add("- ``$functionName``")
        }
        $lines.Add("")
    }

    return ($lines -join "`r`n").TrimEnd() + "`r`n"
}

function New-MarkdownCatalogIndex {
    param([object[]]$Modules)

    $lines = [System.Collections.Generic.List[string]]::new()
    $lines.Add("# Function Catalog")
    $lines.Add("")
    $lines.Add('这里是 canonical 函数目录。它只回答“函数在哪个模块里”，不承担基础语法教学。')
    $lines.Add("")
    $lines.Add("## 使用顺序")
    $lines.Add("")
    $lines.Add("1. 不知道函数在哪个模块，先看下面的模块目录。")
    $lines.Add("2. 进入模块页后，在页内搜索具体函数名。")
    $lines.Add("3. 如果问题是语法怎么写，回到 [../../syntax/index.md](../../syntax/index.md)。")
    $lines.Add("4. 如果问题是金融场景如何组织，回到 [../../finance/index.md](../../finance/index.md)。")
    $lines.Add("")
    $lines.Add("## 模块目录")
    $lines.Add("")
    $lines.Add("| 模块 | 分类页 | 范围 | 函数数 |")
    $lines.Add("| --- | --- | --- | --- |")

    foreach ($module in $Modules) {
        $pageName = "{0}.md" -f $module.File
        $lines.Add("| $($module.ModuleTitle) | [$pageName]($pageName) | $($module.Summary) | $($module.FunctionCount) |")
    }

    $lines.Add("")
    $lines.Add("## 说明")
    $lines.Add("")
    $lines.Add("- 这套目录页由仓库内的函数语料自动整理生成。")
    $lines.Add("- 当前目标是先提供稳定检索层，再逐步补全更细的 canonical 说明。")
    $lines.Add("")

    return ($lines -join "`r`n").TrimEnd() + "`r`n"
}

if (-not (Test-Path -LiteralPath $sourceDir)) {
    throw "Source directory not found: $sourceDir"
}

New-Item -ItemType Directory -Force -Path $outputDir | Out-Null

$modules = foreach ($meta in $moduleOrder) {
    $sourcePath = Join-Path $sourceDir ("{0}.md" -f $meta.File)
    if (-not (Test-Path -LiteralPath $sourcePath)) {
        throw "Missing module source: $sourcePath"
    }

    $module = Parse-TslFunctionModule -Path $sourcePath
    $module | Add-Member -NotePropertyName Summary -NotePropertyValue $meta.Summary
    $module
}

$catalogIndex = New-MarkdownCatalogIndex -Modules $modules
Set-Content -LiteralPath (Join-Path $outputDir "index.md") -Value $catalogIndex -Encoding UTF8

foreach ($module in $modules) {
    $page = New-MarkdownModulePage -Module $module -Summary $module.Summary
    Set-Content -LiteralPath (Join-Path $outputDir ("{0}.md" -f $module.File)) -Value $page -Encoding UTF8
}

Write-Output ("Generated {0} catalog pages in {1}" -f ($modules.Count + 1), $outputDir)