# merge-import.ps1 - harvest a not-yet-fragmented branch's changelog into fragments, then rebuild views.
#
# Use after merging an old-format branch (e.g. master) into your fragment-based branch.
# It captures the other side's old-format changelog entries as fragments (only the IDs
# that don't already exist), rebuilds the four views, and reports any lost IDs.
#
# Usage:
#   powershell -ExecutionPolicy Bypass -File .cursor/changelog/tools/merge-import.ps1            # harvest from working-tree (post union-merge)
#   powershell -ExecutionPolicy Bypass -File .cursor/changelog/tools/merge-import.ps1 -Ref master # harvest directly from a ref

param([string]$Ref = "")

$ErrorActionPreference = "Stop"
$env:PYTHONIOENCODING = "utf-8"

$root = (git rev-parse --show-toplevel 2>$null)
if (-not $root) { Write-Error "not inside a git repository"; exit 1 }
Set-Location $root

$cl = ".cursor/changelog"
$tools = "$cl/tools"

$pyCmd = (Get-Command python -ErrorAction SilentlyContinue)
if (-not $pyCmd) { $pyCmd = (Get-Command python3 -ErrorAction SilentlyContinue) }
if (-not $pyCmd) { Write-Error "python not found"; exit 1 }
$py = $pyCmd.Source

function Get-Ids($path) {
    if (-not (Test-Path $path)) { return @() }
    Select-String -Path $path -Pattern "^### \[(CL-[^\]]+)\]" |
        ForEach-Object { $_.Matches[0].Groups[1].Value } | Sort-Object -Unique
}

$views = @("changelog-full.md", "changelog-recent.md", "changelog-headlines.md")
$tmp = Join-Path $env:TEMP ("cl-import-" + [guid]::NewGuid().ToString("N"))
New-Item -ItemType Directory -Force -Path $tmp | Out-Null
$enc = New-Object System.Text.UTF8Encoding($false)

try {
    if ($Ref) {
        Write-Output "harvest source: ref '$Ref'"
        foreach ($f in $views) {
            $content = (git show "${Ref}:$cl/$f" 2>$null)
            if ($content) {
                [System.IO.File]::WriteAllText((Join-Path $tmp $f), (($content -join "`n") + "`n"), $enc)
            }
        }
    } else {
        Write-Output "harvest source: working-tree (post union-merge)"
        foreach ($f in $views) {
            if (Test-Path "$cl/$f") { Copy-Item -Force "$cl/$f" (Join-Path $tmp $f) }
        }
    }

    $srcFull = Join-Path $tmp "changelog-full.md"
    $srcIds = Get-Ids $srcFull
    Write-Output "source entries: $($srcIds.Count)"

    # parse source into staging fragments (temp/entries/legacy)
    & $py "$tools/migrate_changelog.py" $tmp | Out-Null

    # existing fragment ids in the real repo (filename stem == id)
    $existing = @()
    if (Test-Path "$cl/entries") {
        $existing = Get-ChildItem -Recurse "$cl/entries" -Filter *.md | ForEach-Object { $_.BaseName }
    }

    # copy only NEW ids into real entries/legacy (never overwrite existing fragments)
    $stage = Join-Path $tmp "entries/legacy"
    $added = 0
    if (Test-Path $stage) {
        New-Item -ItemType Directory -Force -Path "$cl/entries/legacy" | Out-Null
        Get-ChildItem "$stage/*.md" | Where-Object { $existing -notcontains $_.BaseName } | ForEach-Object {
            Copy-Item -Force $_.FullName "$cl/entries/legacy/"
            $added++
        }
    }
    Write-Output "new fragments imported: $added"
}
finally {
    Remove-Item -Recurse -Force $tmp -ErrorAction SilentlyContinue
}

# rebuild views from the now-complete entries/
& $py "$tools/changelog_build.py"

# verify: every source id must survive in the rebuilt full view
$nowIds = Get-Ids "$cl/changelog-full.md"
$missing = $srcIds | Where-Object { $nowIds -notcontains $_ }
if ($missing) {
    Write-Output "WARNING: source ids missing after rebuild:"
    $missing | ForEach-Object { Write-Output "  $_" }
    exit 2
}
Write-Output "OK: all $($srcIds.Count) source entries present. total now: $($nowIds.Count)."
Write-Output "next: git add -A; git commit"