# EULE Outlook helper - opens a reply in Outlook Classic from the Postkast page.
#
# Called by Windows for links like:
#   eule-outlook:reply?m=<EntryID>&s=<StoreID>&subj=<subject>&from=<email>&all=1&h=<sha256 prefix>
#   eule-outlook:forward?m=...&s=...&to=<email>&h=...   (delegate: forward with a note)
#   eule-outlook:open?m=...&s=...&subj=...&from=...      (just show the original mail)
#   eule-outlook:new?to=<emails>&cc=<emails>&subj=<subject>&h=...  (a new mail the page prepared)
#
# It finds the message, opens Reply (or Reply All) in a normal Outlook window with
# your signature and the quoted mail, and puts the suggested text at the top.
# The text comes from the clipboard (the page copies it there just before the
# link) and is only used if its hash matches "h", so random clipboard content
# never ends up in a mail. Nothing is ever sent: you review and press Send.
#
# Kept ASCII-only on purpose: Windows PowerShell 5.1 reads downloaded scripts
# without a BOM as ANSI.

param([Parameter(Position = 0)][string]$Url)

$ErrorActionPreference = 'Stop'
Add-Type -AssemblyName System.Web
Add-Type -AssemblyName PresentationFramework

function Show-Error([string]$msg) {
    [void][System.Windows.MessageBox]::Show($msg, 'EULE Outlook helper', 'OK', 'Warning')
}

function Get-ShortHash([string]$text) {
    $sha = [System.Security.Cryptography.SHA256]::Create()
    $bytes = $sha.ComputeHash([System.Text.Encoding]::UTF8.GetBytes($text))
    return (-join ($bytes | ForEach-Object { $_.ToString('x2') })).Substring(0, 16)
}

function From-Base64Url([string]$v) {
    $p = $v.Replace('-', '+').Replace('_', '/')
    switch ($p.Length % 4) { 2 { $p += '==' } 3 { $p += '=' } }
    return [System.Text.Encoding]::UTF8.GetString([Convert]::FromBase64String($p))
}

function Resolve-MessageRef([string]$m, [string]$s) {
    # Accepts what the Outlook MCP connector returns (omcp2_<store hash>_<base64url EntryID>,
    # or the older omcp1_<base64url JSON>) as well as a raw hex EntryID.
    # Anything unreadable gives empty ids, and the caller falls back to subject search.
    $entry = ''; $store = ''
    try {
        if ($m -match '^omcp2_[0-9A-Fa-f]{16}_([A-Za-z0-9_-]{8,4096})$') {
            $entry = From-Base64Url $Matches[1]
            $store = $s
        } elseif ($m -match '^omcp1_([A-Za-z0-9_-]{8,8192})$') {
            $obj = (From-Base64Url $Matches[1]) | ConvertFrom-Json
            $entry = [string]$obj.EntryId
            $store = [string]$obj.StoreId
        } else {
            $entry = $m
            $store = $s
        }
    } catch { $entry = ''; $store = '' }
    if ($entry -notmatch '^[0-9A-Fa-f]{16,1024}$') { $entry = '' }
    if ($store -notmatch '^[0-9A-Fa-f]{16,4096}$') { $store = '' }
    return @{ EntryId = $entry; StoreId = $store }
}

function Get-Addresses([string]$v) {
    # "Name <a@b.ee>, c@d.ee" -> "a@b.ee; c@d.ee". Only plain addresses survive.
    if (-not $v) { return '' }
    $found = [regex]::Matches($v, '[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}')
    $list = @()
    foreach ($f in $found) { if ($list.Count -lt 20 -and $list -notcontains $f.Value) { $list += $f.Value } }
    return ($list -join '; ')
}

function Normalize-Subject([string]$s) {
    if (-not $s) { return '' }
    $s = $s.Trim()
    while ($s -match '^(?i)(re|fw|fwd|vs|vl|sv|aw|wg)\s*:\s*') { $s = $s -replace '^(?i)(re|fw|fwd|vs|vl|sv|aw|wg)\s*:\s*', '' }
    return $s.Trim().ToLowerInvariant()
}

function Find-ByHeaders($ns, [string]$subject, [string]$from) {
    # Fallback when the EntryID is missing or no longer valid (e.g. the morning
    # task ran on another computer): newest matching mail of the last 45 days.
    $want = Normalize-Subject $subject
    if (-not $want) { return $null }
    $since = (Get-Date).AddDays(-45).ToString('g')
    $skip = @(3, 4, 5, 16, 23)   # Deleted, Outbox, Sent, Drafts, Junk
    $skipIds = @{}
    foreach ($id in $skip) { try { $skipIds[$ns.GetDefaultFolder($id).EntryID] = $true } catch {} }

    $best = $null
    $queue = New-Object System.Collections.Queue
    foreach ($store in $ns.Stores) { try { $queue.Enqueue($store.GetRootFolder()) } catch {} }
    while ($queue.Count -gt 0) {
        $folder = $queue.Dequeue()
        try { foreach ($sub in $folder.Folders) { $queue.Enqueue($sub) } } catch {}
        if ($skipIds.ContainsKey($folder.EntryID)) { continue }
        if ($folder.DefaultItemType -ne 0) { continue }   # mail folders only
        try { $items = $folder.Items.Restrict("[ReceivedTime] >= '$since'") } catch { continue }
        foreach ($it in $items) {
            if ($it.Class -ne 43) { continue }            # MailItem
            if ((Normalize-Subject $it.Subject) -ne $want) { continue }
            if ($from) {
                $addr = ''
                try { $addr = [string]$it.SenderEmailAddress } catch {}
                if ($addr -and $addr -notlike "*$from*") { continue }
            }
            if (-not $best -or $it.ReceivedTime -gt $best.ReceivedTime) { $best = $it }
        }
    }
    return $best
}

try {
    if (-not $Url -or $Url -notmatch '^eule-outlook:(//)?(reply|forward|open|new)\b') { throw 'Missing or invalid link.' }
    $action = $Matches[2]
    $query = ($Url -split '\?', 2)[1]
    $q = [System.Web.HttpUtility]::ParseQueryString([string]$query)

    $ref = Resolve-MessageRef ([string]$q['m']) ([string]$q['s'])
    $entryId = $ref.EntryId
    $storeId = $ref.StoreId
    $replyAll = $q['all'] -eq '1'
    $hash = [string]$q['h']

    $outlook = New-Object -ComObject Outlook.Application
    $ns = $outlook.GetNamespace('MAPI')

    $item = $null
    if ($action -eq 'new') {
        $reply = $outlook.CreateItem(0)   # olMailItem
        $reply.To = Get-Addresses ([string]$q['to'])
        $cc = Get-Addresses ([string]$q['cc'])
        if ($cc) { $reply.CC = $cc }
        $subj = ([string]$q['subj']) -replace "[`r`n`t]", ' '
        if ($subj.Length -gt 250) { $subj = $subj.Substring(0, 250) }
        $reply.Subject = $subj
    }
    elseif ($entryId) {
        try {
            if ($storeId) { $item = $ns.GetItemFromID($entryId, $storeId) } else { $item = $ns.GetItemFromID($entryId) }
        } catch { $item = $null }
    }
    if ($action -ne 'new') {
        if (-not $item) { $item = Find-ByHeaders $ns ([string]$q['subj']) ([string]$q['from']) }
        if (-not $item) { throw "Could not find the mail in Outlook:`n$($q['subj'])" }
    }

    if ($action -eq 'open') {
        $item.Display()
        try { $item.GetInspector.Activate() } catch {}
        return
    }

    if ($action -eq 'new') {
        # created above
    } elseif ($action -eq 'forward') {
        $reply = $item.Forward()
        $to = [string]$q['to']
        if ($to -match '^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$') { $reply.To = $to }
    } else {
        $reply = if ($replyAll) { $item.ReplyAll() } else { $item.Reply() }
    }
    $reply.Display()   # Outlook adds the signature here

    # Suggested text from the clipboard, only if it is exactly what the page copied
    $text = $null
    if ($hash -match '^[0-9a-f]{16}$') {
        try { $clip = Get-Clipboard -Raw } catch { $clip = $null }
        if ($clip) {
            $clip = $clip -replace "`r", ''
            if ((Get-ShortHash $clip) -eq $hash) { $text = $clip.TrimEnd() }
        }
    }

    if ($text) {
        $inserted = $false
        try {
            # Typing into the Word editor keeps Outlook's own compose font
            $doc = $reply.GetInspector.WordEditor
            $doc.Range(0, 0).InsertBefore(($text -replace "`n", "`r") + "`r")
            $inserted = $true
        } catch {}
        if (-not $inserted) {
            if ($reply.BodyFormat -eq 2) {
                $html = [System.Web.HttpUtility]::HtmlEncode($text) -replace "`n", '<br>'
                $body = $reply.HTMLBody
                $m = [regex]::Match($body, '<body[^>]*>', 'IgnoreCase')
                if ($m.Success) {
                    $reply.HTMLBody = $body.Insert($m.Index + $m.Length, "<div>$html</div><br>")
                } else {
                    $reply.HTMLBody = "<div>$html</div><br>" + $body
                }
            } else {
                $reply.Body = $text + "`r`n`r`n" + $reply.Body
            }
        }
    }

    try { $reply.GetInspector.Activate() } catch {}
}
catch {
    Show-Error ("Could not open the mail in Outlook.`n`n" + $_.Exception.Message + "`n`nThe reply text is still on the clipboard - paste it with Ctrl+V.")
}