<#
.SYNOPSIS
  清空 hybrid 知识库（Milvus biz_hybrid + MySQL api_document + L0），并从 knowledge_base 全量重建。

.DESCRIPTION
  对应 dense+BM25 混合检索上线后的数据迁移步骤：

    1) 检查服务健康
    2) 可选：查看当前 /api/knowledge/stats
    3) POST /api/knowledge/rebuild-hybrid?confirm=REBUILD
       - drop + recreate milvus.collection（默认 biz_hybrid）
       - 清空 MySQL api_document
       - 清空内存 L0 索引
       - 扫描 knowledge_base/**/*.md 强制导入并写入 dense+BM25

  不会删除旧的 legacy collection `biz`（知识主路径已不再使用它）。

.PARAMETER BaseUrl
  服务根地址，默认 http://localhost:9900

.PARAMETER Confirm
  必须为 REBUILD 才会真正执行（防止误触）

.PARAMETER SkipStats
  跳过重建前后的 stats 查询

.EXAMPLE
  # 先启动 Spring Boot，再执行：
  .\scripts\rebuild-hybrid-knowledge.ps1 -Confirm REBUILD

.EXAMPLE
  .\scripts\rebuild-hybrid-knowledge.ps1 -BaseUrl http://127.0.0.1:9900 -Confirm REBUILD
#>

[CmdletBinding()]
param(
    [string]$BaseUrl = "http://localhost:9900",
    [ValidateSet("REBUILD")]
    [Parameter(Mandatory = $true)]
    [string]$Confirm,
    [switch]$SkipStats
)

$ErrorActionPreference = "Stop"

function Write-Step([string]$Message) {
    Write-Host ""
    Write-Host "==> $Message" -ForegroundColor Cyan
}

function Invoke-Json {
    param(
        [Parameter(Mandatory = $true)][string]$Method,
        [Parameter(Mandatory = $true)][string]$Url,
        [int]$TimeoutSec = 3600
    )
    try {
        $resp = Invoke-WebRequest -Method $Method -Uri $Url -TimeoutSec $TimeoutSec
        $body = $resp.Content
        if ([string]::IsNullOrWhiteSpace($body)) {
            return @{ statusCode = [int]$resp.StatusCode; body = $null }
        }
        return @{
            statusCode = [int]$resp.StatusCode
            body       = $body | ConvertFrom-Json
        }
    }
    catch {
        $status = $null
        $raw = $null
        if ($_.Exception.Response) {
            $status = [int]$_.Exception.Response.StatusCode
            try {
                $stream = $_.Exception.Response.GetResponseStream()
                $reader = New-Object System.IO.StreamReader($stream)
                $raw = $reader.ReadToEnd()
            }
            catch { }
        }
        throw "HTTP $Method $Url failed (status=$status): $($_.Exception.Message)`n$raw"
    }
}

$BaseUrl = $BaseUrl.TrimEnd("/")

Write-Host "Hybrid knowledge rebuild" -ForegroundColor Green
Write-Host "  BaseUrl : $BaseUrl"
Write-Host "  Confirm : $Confirm"
Write-Host "  Source  : knowledge_base/ (server-side knowledge.base-path)"
Write-Host ""
Write-Host "This will DESTROY data in:" -ForegroundColor Yellow
Write-Host "  - Milvus collection milvus.collection (default: biz_hybrid)"
Write-Host "  - MySQL table api_document"
Write-Host "  - In-memory L0 knowledge index"
Write-Host "Then re-import all markdown under knowledge_base."
Write-Host ""

# 1) health
Write-Step "Check service health"
try {
    $health = Invoke-Json -Method GET -Url "$BaseUrl/milvus/health" -TimeoutSec 30
    Write-Host ("  milvus health status={0}" -f $health.statusCode)
    if ($health.body) {
        $health.body | ConvertTo-Json -Depth 6 | Write-Host
    }
}
catch {
    Write-Host "  WARN: /milvus/health failed: $_" -ForegroundColor Yellow
    Write-Host "  Continue if app is up but milvus health endpoint has issues."
}

# 2) stats before
if (-not $SkipStats) {
    Write-Step "Knowledge stats (before)"
    try {
        $before = Invoke-Json -Method GET -Url "$BaseUrl/api/knowledge/stats" -TimeoutSec 30
        $before.body | ConvertTo-Json -Depth 6 | Write-Host
    }
    catch {
        Write-Host "  WARN: stats before failed: $_" -ForegroundColor Yellow
    }
}

# 3) rebuild
Write-Step "POST /api/knowledge/rebuild-hybrid?confirm=REBUILD"
$rebuildUrl = "$BaseUrl/api/knowledge/rebuild-hybrid?confirm=$Confirm"
$rebuild = Invoke-Json -Method POST -Url $rebuildUrl -TimeoutSec 7200
Write-Host ("  HTTP {0}" -f $rebuild.statusCode)
$rebuild.body | ConvertTo-Json -Depth 12 | Write-Host

if (-not $rebuild.body.success) {
    Write-Host ""
    Write-Host "Rebuild reported failure. Inspect details above." -ForegroundColor Red
    exit 2
}

# 4) stats after
if (-not $SkipStats) {
    Write-Step "Knowledge stats (after)"
    try {
        $after = Invoke-Json -Method GET -Url "$BaseUrl/api/knowledge/stats" -TimeoutSec 30
        $after.body | ConvertTo-Json -Depth 6 | Write-Host
    }
    catch {
        Write-Host "  WARN: stats after failed: $_" -ForegroundColor Yellow
    }
}

Write-Host ""
Write-Host "Done." -ForegroundColor Green
Write-Host "Next:"
Write-Host "  1) Ensure application.yml has:"
Write-Host "       milvus.collection: biz_hybrid"
Write-Host "       retrieval.search.mode: hybrid"
Write-Host "  2) Smoke test lookup_knowledge / chat with a known doc query"
Write-Host "  3) Optional: drop legacy collection 'biz' manually in Zilliz console if no longer needed"
exit 0