#Requires -Version 5.1
<#
.SYNOPSIS
    Installs bottom(btm) process monitor from GitHub Nightly releases.

.DESCRIPTION
    Auto-detects the latest Nightly release from
    https://github.com/ClementTsang/bottom/releases, downloads the zip
    file matching your Windows architecture, and installs it.

    Supported architectures:
      - x64  (AMD64 / Intel 64bit)
      - ARM64 (Snapdragon X Elite, Qualcomm ARM, etc.)

.PARAMETER InstallDir
    Directory to install btm.exe. Default: $env:USERPROFILE\.local\bin

.PARAMETER AddToPath
    Whether to permanently add InstallDir to user PATH. Default: $true

.EXAMPLE
    .\install-bottom.ps1
    .\install-bottom.ps1 -InstallDir "C:\tools\bin"
    .\install-bottom.ps1 -AddToPath $false

.NOTES
    If execution policy error occurs:
      Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
#>

[CmdletBinding()]
param(
    [string] $InstallDir = "$env:USERPROFILE\.local\bin",
    [bool]   $AddToPath = $true
)

Set-StrictMode -Version Latest
$ErrorActionPreference = 'Stop'

# ────────────────────────────────────────────
# Constants
# ────────────────────────────────────────────
$REPO    = "ClementTsang/bottom"
$API_URL = "https://api.github.com/repos/$REPO/releases"

# ────────────────────────────────────────────
# Utility functions
# ────────────────────────────────────────────
function Write-Info    { param([string]$msg) Write-Host "[INFO]  $msg" -ForegroundColor Cyan }
function Write-Warn    { param([string]$msg) Write-Host "[WARN]  $msg" -ForegroundColor Yellow }
function Write-Success { param([string]$msg) Write-Host "[OK]    $msg" -ForegroundColor Green }
function Write-Err     { param([string]$msg) Write-Host "[ERROR] $msg" -ForegroundColor Red; exit 1 }

# ────────────────────────────────────────────
# Enforce TLS 1.2 (for Windows 7/8.1 compatibility)
# ────────────────────────────────────────────
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

# ────────────────────────────────────────────
# Architecture detection
# ────────────────────────────────────────────
function Get-Platform {
    # 1) Check environment variables first (even 32-bit PowerShell on
    #    Windows ARM can correctly detect OS architecture)
    #    - Native process   : PROCESSOR_ARCHITECTURE = AMD64 / ARM64 / x86
    #    - WOW64(32bit on 64bit): PROCESSOR_ARCHITECTURE = x86,
    #                              PROCESSOR_ARCHITEW6432 = AMD64 or ARM64 (actual OS arch)
    $envArch = $env:PROCESSOR_ARCHITEW6432
    if (-not $envArch) { $envArch = $env:PROCESSOR_ARCHITECTURE }

    switch -Regex ($envArch) {
        '^AMD64$' { return "x86_64-pc-windows-msvc" }
        '^ARM64$' { return "aarch64-pc-windows-msvc" }
        '^x86$'   { return "i686-pc-windows-msvc" }
    }

    # 2) Fallback: .NET RuntimeInformation (requires PS 5.1 + .NET Framework 4.7.1+)
    try {
        $arch = [System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture
        switch ($arch) {
            'X64'   { return "x86_64-pc-windows-msvc" }
            'Arm64' { return "aarch64-pc-windows-msvc" }
            'X86'   { return "i686-pc-windows-msvc" }
            default { Write-Err "Unsupported architecture: $arch" }
        }
    } catch {
        Write-Err "Failed to detect architecture: $_"
    }
}

# ────────────────────────────────────────────
# Get latest Nightly release tag
# ────────────────────────────────────────────
function Get-LatestNightlyTag {
    Write-Info "Fetching latest Nightly release from GitHub API..."

    try {
        $releases = Invoke-RestMethod -Uri $API_URL -UseBasicParsing `
            -Headers @{ 'User-Agent' = 'install-bottom-ps1' }
    } catch {
        Write-Err "Failed to call GitHub API: $_"
    }

    # Get first item where prerelease=true and tag_name starts with 'nightly-'
    $nightly = $releases | Where-Object {
        $_.prerelease -eq $true -and $_.tag_name -like 'nightly-*'
    } | Select-Object -First 1

    if (-not $nightly) {
        Write-Err "Could not find Nightly release."
    }

    return $nightly.tag_name
}

# ────────────────────────────────────────────
# Build download URL
# ────────────────────────────────────────────
function Get-DownloadUrl {
    param([string]$Tag, [string]$Triple)
    $filename = "bottom_${Triple}.zip"
    return "https://github.com/$REPO/releases/download/$Tag/$filename"
}

# ────────────────────────────────────────────
# Download, extract & install
# ────────────────────────────────────────────
function Install-Bottom {
    param([string]$Url)

    # Create temp directory
    $tmpDir = Join-Path $env:TEMP "bottom_install_$(Get-Random)"
    New-Item -ItemType Directory -Path $tmpDir | Out-Null

    try {
        $zipPath = Join-Path $tmpDir "bottom.zip"

        Write-Info "Downloading: $Url"
        try {
            # Suppress progress bar in PowerShell 5+
            $ProgressPreference = 'SilentlyContinue'
            Invoke-WebRequest -Uri $Url -OutFile $zipPath -UseBasicParsing
            $ProgressPreference = 'Continue'
        } catch {
            Write-Err "Download failed: $_"
        }

        Write-Info "Extracting..."
        Expand-Archive -Path $zipPath -DestinationPath $tmpDir -Force

        # Find btm.exe
        $btmExe = Get-ChildItem -Path $tmpDir -Recurse -Filter "btm.exe" |
                  Select-Object -First 1
        if (-not $btmExe) {
            Write-Err "Cannot find 'btm.exe' in the archive."
        }

        # Create install directory
        if (-not (Test-Path $InstallDir)) {
            New-Item -ItemType Directory -Path $InstallDir -Force | Out-Null
        }

        $destPath = Join-Path $InstallDir "btm.exe"
        Write-Info "Installing: $destPath"
        Copy-Item -Path $btmExe.FullName -Destination $destPath -Force

        Write-Success "Installation complete!"

        # Check version
        Write-Info "Version check:"
        & $destPath --version

    } finally {
        # Cleanup temp files
        if (Test-Path $tmpDir) {
            Remove-Item -Path $tmpDir -Recurse -Force -ErrorAction SilentlyContinue
        }
    }
}

# ────────────────────────────────────────────
# Add to PATH (user environment variable)
# ────────────────────────────────────────────
function Add-ToUserPath {
    param([string]$Dir)

    $currentPath = [Environment]::GetEnvironmentVariable('PATH', 'User')
    if (-not $currentPath) { $currentPath = '' }
    # Force array even with single result (for safe -contains check)
    $dirs = @($currentPath -split ';' | Where-Object { $_ -ne '' })

    if ($dirs -contains $Dir) {
        Write-Info "'$Dir' is already in your PATH."
        return
    }

    $newPath = ($dirs + $Dir) -join ';'
    [Environment]::SetEnvironmentVariable('PATH', $newPath, 'User')

    # Also reflect in current session
    $env:PATH = "$env:PATH;$Dir"

    Write-Success "'$Dir' has been permanently added to user PATH."
    Write-Warn "Open a new terminal for PATH changes to take effect."
}

# ────────────────────────────────────────────
# 메인
# ────────────────────────────────────────────
function Main {
    Write-Info "===== bottom(btm) install script (Windows PowerShell) ====="

    $triple = Get-Platform
    Write-Info "Detected platform: $triple"

    $tag = Get-LatestNightlyTag
    Write-Info "Latest Nightly tag: $tag"

    $url = Get-DownloadUrl -Tag $tag -Triple $triple
    Install-Bottom -Url $url

    if ($AddToPath) {
        Add-ToUserPath -Dir $InstallDir
    } else {
        Write-Warn "Skipping automatic PATH registration."
        Write-Warn "Add to PATH manually: $InstallDir"
    }

    Write-Success "All tasks completed."
    Write-Info  "Usage: btm"
}

Main