<#
.SYNOPSIS
    HTTP auto-update launcher for CMBot (docs/10-lan-update.md, stage 3).

.DESCRIPTION
    Run instead of launching CMBot.exe directly. On each start it:
      1. reads the local version from app\version.txt;
      2. reads update_source/update_user/update_pass from data\config\app_config.json;
      3. downloads manifest.json and, when newer, downloads the release zip;
      4. verifies SHA-256, extracts to staging\app.new, and switches app/app.old;
      5. launches app\CMBot.exe with CMBOT_DATA_DIR pointed at data\.

    Degrades safely for normal updates: network errors, malformed manifests,
    failed downloads, bad hashes, or bad zips leave the existing app\ version
    in place and launch it.

.PARAMETER InstallRoot
    Install directory holding Launcher.exe, app\, app.old\, data\, staging\.
    Defaults to the launcher's own folder.

.PARAMETER NoLaunch
    Do everything except start the app. For testing the update flow.
#>
[CmdletBinding()]
param(
    [string]$InstallRoot = $PSScriptRoot,
    [switch]$NoLaunch
)

$ErrorActionPreference = "Stop"

$AppExe       = "CMBot.exe"
$ManifestName = "manifest.json"
$VersionFileName = "version.txt"

$AppDir      = Join-Path $InstallRoot "app"
$OldAppDir   = Join-Path $InstallRoot "app.old"
$DataDir     = Join-Path $InstallRoot "data"
$StagingDir  = Join-Path $InstallRoot "staging"
$ConfigFile  = Join-Path $DataDir "config\app_config.json"
$LogFile     = Join-Path $InstallRoot "launcher.log"

function Write-Log {
    param([string]$Message)
    $line = "{0}  {1}" -f (Get-Date -Format "yyyy-MM-dd HH:mm:ss"), $Message
    Write-Host $line
    try { Add-Content -LiteralPath $LogFile -Value $line -Encoding UTF8 } catch { }
}

function Get-LocalVersion {
    $versionFile = Join-Path $AppDir $VersionFileName
    if (Test-Path -LiteralPath $versionFile) {
        return (Get-Content -LiteralPath $versionFile -Raw).TrimStart([char]0xFEFF).Trim()
    }
    return ""
}

function Get-UpdateConfig {
    $result = [ordered]@{
        Source = ""
        User = ""
        Pass = ""
    }
    if (-not (Test-Path -LiteralPath $ConfigFile)) {
        return $result
    }
    try {
        $cfg = Get-Content -LiteralPath $ConfigFile -Raw | ConvertFrom-Json
        $result.Source = [string]$cfg.update_source
        $result.User = [string]$cfg.update_user
        $result.Pass = [string]$cfg.update_pass
    } catch {
        Write-Log "Cannot read update config: $_"
    }
    return $result
}

function ConvertTo-VersionParts {
    param([string]$Text)
    $parts = @(0, 0, 0)
    if ($Text) {
        $chunks = $Text.Trim().Split(".")
        for ($i = 0; $i -lt 3 -and $i -lt $chunks.Count; $i++) {
            $digits = ($chunks[$i] -replace '^(\d*).*$', '$1')
            if ($digits) { $parts[$i] = [int]$digits }
        }
    }
    return ,$parts
}

function Test-IsNewer {
    param([string]$Remote, [string]$Local)
    $r = ConvertTo-VersionParts $Remote
    $l = ConvertTo-VersionParts $Local
    for ($i = 0; $i -lt 3; $i++) {
        if ($r[$i] -gt $l[$i]) { return $true }
        if ($r[$i] -lt $l[$i]) { return $false }
    }
    return $false
}

function Get-AuthHeaders {
    param(
        [string]$User,
        [string]$Pass
    )
    $headers = @{}
    if ($User -or $Pass) {
        $bytes = [System.Text.Encoding]::UTF8.GetBytes(("{0}:{1}" -f $User, $Pass))
        $headers["Authorization"] = "Basic " + [Convert]::ToBase64String($bytes)
    }
    return $headers
}

function Resolve-ManifestUrl {
    param([string]$Source)
    $uri = [System.Uri]$Source
    if ([System.IO.Path]::GetFileName($uri.AbsolutePath).ToLowerInvariant() -eq $ManifestName) {
        return $uri.AbsoluteUri
    }
    if (-not $Source.EndsWith("/")) {
        $Source = "$Source/"
        $uri = [System.Uri]$Source
    }
    return (New-Object -TypeName System.Uri -ArgumentList $uri, $ManifestName).AbsoluteUri
}

function Resolve-ReleaseUrl {
    param(
        [string]$ManifestUrl,
        [string]$ReleaseUrl
    )
    $uri = $null
    if ([System.Uri]::TryCreate($ReleaseUrl, [System.UriKind]::Absolute, [ref]$uri)) {
        return $uri.AbsoluteUri
    }
    return (New-Object -TypeName System.Uri -ArgumentList ([System.Uri]$ManifestUrl), $ReleaseUrl).AbsoluteUri
}

function Invoke-JsonGet {
    param(
        [string]$Url,
        [hashtable]$Headers
    )
    $response = Invoke-WebRequest -Uri $Url -Headers $Headers -UseBasicParsing -TimeoutSec 15
    return $response.Content | ConvertFrom-Json
}

function Save-HttpFile {
    param(
        [string]$Url,
        [string]$Destination,
        [hashtable]$Headers
    )
    Invoke-WebRequest -Uri $Url -Headers $Headers -UseBasicParsing -TimeoutSec 120 -OutFile $Destination
}

function Remove-PathIfExists {
    param([string]$Path)
    if (Test-Path -LiteralPath $Path) {
        Remove-Item -LiteralPath $Path -Recurse -Force
    }
}

function Get-PackageRoot {
    param([string]$ExtractDir)
    if (Test-Path -LiteralPath (Join-Path $ExtractDir $AppExe)) {
        return $ExtractDir
    }
    $children = @(Get-ChildItem -LiteralPath $ExtractDir -Directory)
    if ($children.Count -eq 1) {
        $candidate = $children[0].FullName
        if (Test-Path -LiteralPath (Join-Path $candidate $AppExe)) {
            return $candidate
        }
    }
    return ""
}

function Assert-PackageValid {
    param(
        [string]$PackageRoot,
        [string]$ExpectedVersion
    )
    if (-not $PackageRoot -or -not (Test-Path -LiteralPath (Join-Path $PackageRoot $AppExe))) {
        throw "downloaded package does not contain $AppExe"
    }
    $versionFile = Join-Path $PackageRoot $VersionFileName
    if (-not (Test-Path -LiteralPath $versionFile)) {
        throw "downloaded package does not contain $VersionFileName"
    }
    $actualVersion = (Get-Content -LiteralPath $versionFile -Raw).TrimStart([char]0xFEFF).Trim()
    if ($actualVersion -ne $ExpectedVersion) {
        throw "package version '$actualVersion' does not match manifest '$ExpectedVersion'"
    }
}

function Test-AppRunning {
    $name = [System.IO.Path]::GetFileNameWithoutExtension($AppExe)
    $exePath = Join-Path $AppDir $AppExe
    $running = Get-Process -Name $name -ErrorAction SilentlyContinue | Where-Object {
        try { $_.Path -eq $exePath } catch { $false }
    }
    return [bool]$running
}

function Switch-AppDirectory {
    param([string]$PackageRoot)
    if (Test-AppRunning) {
        throw "$AppExe is already running"
    }
    if (Test-Path -LiteralPath $OldAppDir) {
        Remove-Item -LiteralPath $OldAppDir -Recurse -Force
    }
    if (Test-Path -LiteralPath $AppDir) {
        Move-Item -LiteralPath $AppDir -Destination $OldAppDir
    }
    try {
        Move-Item -LiteralPath $PackageRoot -Destination $AppDir
    } catch {
        if ((-not (Test-Path -LiteralPath $AppDir)) -and (Test-Path -LiteralPath $OldAppDir)) {
            Move-Item -LiteralPath $OldAppDir -Destination $AppDir
        }
        throw
    }
}

function Invoke-Update {
    param(
        [string]$Source,
        [string]$User,
        [string]$Pass,
        [string]$LocalVersion
    )

    $manifestUrl = Resolve-ManifestUrl $Source
    $headers = Get-AuthHeaders -User $User -Pass $Pass

    Write-Log "Checking update manifest: $manifestUrl"
    $m = Invoke-JsonGet -Url $manifestUrl -Headers $headers

    $remoteVer = [string]$m.version
    if (-not $remoteVer) {
        Write-Log "Manifest has no version - skip update."
        return
    }
    if (-not (Test-IsNewer $remoteVer $LocalVersion)) {
        Write-Log "Up to date (local '$LocalVersion', remote '$remoteVer')."
        return
    }

    $releaseField = [string]$m.url
    $expectedHash = ([string]$m.sha256).Trim().ToLowerInvariant()
    if (-not $releaseField -or -not $expectedHash) {
        throw "manifest must contain url and sha256"
    }
    $releaseUrl = Resolve-ReleaseUrl -ManifestUrl $manifestUrl -ReleaseUrl $releaseField

    $zipPath = Join-Path $StagingDir ("{0}.zip" -f $remoteVer)
    $extractDir = Join-Path $StagingDir "app.new"
    Remove-PathIfExists -Path $zipPath
    Remove-PathIfExists -Path $extractDir

    Write-Log "Downloading v$remoteVer from $releaseUrl ..."
    Save-HttpFile -Url $releaseUrl -Destination $zipPath -Headers $headers

    if ($m.size) {
        $actualSize = (Get-Item -LiteralPath $zipPath).Length
        if ($actualSize -ne [int64]$m.size) {
            throw "download size mismatch: got $actualSize, expected $($m.size)"
        }
    }

    $actualHash = (Get-FileHash -LiteralPath $zipPath -Algorithm SHA256).Hash.ToLowerInvariant()
    if ($actualHash -ne $expectedHash) {
        throw "sha256 mismatch"
    }

    Expand-Archive -LiteralPath $zipPath -DestinationPath $extractDir -Force
    $packageRoot = Get-PackageRoot -ExtractDir $extractDir
    Assert-PackageValid -PackageRoot $packageRoot -ExpectedVersion $remoteVer

    Switch-AppDirectory -PackageRoot $packageRoot
    Remove-PathIfExists -Path $zipPath
    Remove-PathIfExists -Path $extractDir
    Write-Log "Installed and switched to v$remoteVer."
}

# -- main --------------------------------------------------------------------

New-Item -ItemType Directory -Force -Path $StagingDir | Out-Null
New-Item -ItemType Directory -Force -Path $DataDir | Out-Null

$local = Get-LocalVersion
$cfg = Get-UpdateConfig

if ($cfg.Source) {
    try {
        Invoke-Update -Source $cfg.Source -User $cfg.User -Pass $cfg.Pass -LocalVersion $local
    } catch {
        Write-Log "Update skipped (degraded to local version): $_"
    }
} else {
    Write-Log "No update_source configured - skip update check."
}

$current = Get-LocalVersion
$exe = Join-Path $AppDir $AppExe
if (-not (Test-Path -LiteralPath $exe)) {
    Write-Log "ERROR: executable not found: $exe"
    exit 1
}

if ($NoLaunch) {
    Write-Log "NoLaunch: would start $exe v$current (CMBOT_DATA_DIR=$DataDir)"
    exit 0
}

Write-Log "Launching v$current ..."
$env:CMBOT_DATA_DIR = $DataDir
Start-Process -FilePath $exe