function nightly_version($date) {
	$date_str = $date.tostring("yyyyMMdd") 
	warn "this is a nightly version: downloaded files won't be verified"
	"nightly-$date_str"
}

function install_app($app, $architecture, $global) {
	$app, $manifest, $bucket, $url = locate $app
	$use_cache = $true
	$check_hash = $true

	if(!$manifest) {
		abort "couldn't find manifest for $app$(if($url) { " at the URL $url" })"
	}

	$version = $manifest.version
	if(!$version) { abort "manifest doesn't specify a version" }
	if($version -match '[^\w\.\-_]') {
		abort "manifest version has unsupported character '$($matches[0])'"
	}

	$is_nightly = $version -eq 'nightly'
	if ($is_nightly) {
		$version = nightly_version $(get-date)
		$check_hash = $false
	}

	echo "installing $app ($version)"

	$dir = ensure (versiondir $app $version $global)

	$fname = dl_urls $app $version $manifest $architecture $dir $use_cache $check_hash
	unpack_inno $fname $manifest $dir
	pre_install $manifest
	run_installer $fname $manifest $architecture $dir
	ensure_install_dir_not_in_path $dir $global
	create_shims $manifest $dir $global
	if($global) { ensure_scoop_in_path $global } # can assume local scoop is in path
	env_add_path $manifest $dir $global
	env_set $manifest $dir $global
	post_install $manifest

	# save info for uninstall
	save_installed_manifest $app $bucket $dir $url
	save_install_info @{ 'architecture' = $architecture; 'url' = $url; 'bucket' = $bucket } $dir

	success "$app ($version) was installed successfully!"

	show_notes $manifest
}

function ensure_architecture($architecture_opt) {
	switch($architecture_opt) {
		'' { return default_architecture }
		{ @('32bit','64bit') -contains $_ } { return $_ }
		default { abort "invalid architecture: '$architecture'"}
	}
}

function cache_path($app, $version, $url) {
	"$cachedir\$app#$version#$($url -replace '[^\w\.\-]+', '_')"
}

function appname_from_url($url) {
	(split-path $url -leaf) -replace '.json$', ''
}

function locate($app) {
	$manifest, $bucket, $url = $null, $null, $null

	# check if app is a url
	if($app -match '^((ht)|f)tps?://') {
		$url = $app
		$app = appname_from_url $url
		$manifest = url_manifest $url
	} else {
		# check buckets
		$manifest, $bucket = find_manifest $app

		if(!$manifest) {
			# couldn't find app in buckets: check if it's a local path
			$path = $app
			if(!$path.endswith('.json')) { $path += '.json' }
			if(test-path $path) {
				$url = "$(resolve-path $path)"
				$app = appname_from_url $url
				$manifest, $bucket = url_manifest $url
			}
		}
	}

	return $app, $manifest, $bucket, $url
}

function dl_with_cache($app, $version, $url, $to, $cookies, $use_cache = $true) {
	$cached = fullpath (cache_path $app $version $url)
	if(!$use_cache) { warn "cache is being ignored" }

	if(!(test-path $cached) -or !$use_cache) {
		$null = ensure $cachedir
		write-host "downloading $url..." -nonewline
		dl_progress $url "$cached.download" $cookies
		mv "$cached.download" $cached -force
		write-host "done"
	} else { write-host "loading $url from cache..."}
	cp $cached $to
}

function dl_progress($url, $to, $cookies) {
	$wc = new-object net.webclient
	$wc.headers.add('User-Agent', 'Scoop/1.0')
	$wc.headers.add('Cookie', (cookie_header $cookies))

	if([console]::isoutputredirected) {
		# can't set cursor position: just do simple download
		$wc.downloadfile($url, $to)
		return
	}

	$left = [console]::cursorleft
	$top = [console]::cursortop
	register-objectevent $wc downloadprogresschanged progress | out-null
	register-objectevent $wc downloadfilecompleted complete | out-null
	try {
		$wc.downloadfileasync($url, $to)

		function is_complete {
			try {
				$complete = get-event complete -ea stop
				$err = $complete.sourceeventargs.error
				if($err) { abort "$($err.message)" }
				$true
			} catch {
				$false
			}
		}

		$last_p = -1
		while(!(is_complete)) {
			$e = wait-event progress -timeout 1
			if(!$e) { continue } # avoid deadlock

			remove-event progress
			$p = $e.sourceeventargs.progresspercentage
			if($p -ne $last_p) {
				[console]::setcursorposition($left, $top)
				write-host "$p%" -nonewline
				$last_p = $p
			}
		}
		remove-event complete
	} finally {
		remove-event *
		unregister-event progress
		unregister-event complete

		$wc.cancelasync()
		$wc.dispose()
	}
	[console]::setcursorposition($left, $top)
}

function dl_urls($app, $version, $manifest, $architecture, $dir, $use_cache = $true, $check_hash = $true) {
	# can be multiple urls: if there are, then msi or installer should go last,
	# so that $fname is set properly
	$urls = @(url $manifest $architecture)

	# can be multiple cookies: they will be used for all HTTP requests.
	$cookies = $manifest.cookie

	$fname = $null

	# extract_dir and extract_to in manifest are like queues: for each url that
	# needs to be extracted, will get the next dir from the queue
	$extract_dirs = @(extract_dir $manifest $architecture)
	$extract_tos = @(extract_to $manifest $architecture)
	$extracted = 0;

	foreach($url in $urls) {
		$fname = split-path $url -leaf

		dl_with_cache $app $version $url "$dir\$fname" $cookies $use_cache

		if($check_hash) {
			$ok, $err = check_hash "$dir\$fname" $url $manifest $architecture
			if(!$ok) {
				# rm cached
				$cached = cache_path $app $version $url
				if(test-path $cached) { rm -force $cached }
				abort $err
			}
		}

		$extract_dir = $extract_dirs[$extracted]
		$extract_to = $extract_tos[$extracted]

		# work out extraction method, if applicable
		$extract_fn = $null
		if($fname -match '\.zip$') { # unzip
			$extract_fn = 'unzip'
		} elseif($fname -match '\.msi$') {
			# check manifest doesn't use deprecated install method
			$msi = msi $manifest $architecture
			if(!$msi) {
				$extract_fn = 'extract_msi'
			} else {
				warn "MSI install is deprecated. If you maintain this manifest, please refer to the manifest reference docs"
			}
		} elseif(file_requires_7zip $fname) { # 7zip
			if(!(7zip_installed)) {
				warn "aborting: you'll need to run 'scoop uninstall $app' to clean up"
				abort "7-zip is required. you can install it with 'scoop install 7zip'"
			}
			$extract_fn = 'extract_7zip'
		}

		if($extract_fn) {
			write-host "extracting..." -nonewline
			$null = mkdir "$dir\_scoop_extract"
			& $extract_fn "$dir\$fname" "$dir\_scoop_extract"
			if ($extract_to) {
				$null = mkdir "$dir\$extract_to" -force
			}
			# fails if zip contains long paths (e.g. atom.json)
			#cp "$dir\_scoop_extract\$extract_dir\*" "$dir\$extract_to" -r -force -ea stop
			movedir "$dir\_scoop_extract\$extract_dir" "$dir\$extract_to"

			if(test-path "$dir\_scoop_extract") { # might have been moved by movedir
				try {
					rm -r -force "$dir\_scoop_extract" -ea stop
				} catch [system.io.pathtoolongexception] {
					cmd /c "rmdir /s /q $dir\_scoop_extract"
				}
			}

			rm "$dir\$fname"
			write-host "done"

			$extracted++
		}
	}

	$fname # returns the last downloaded file
}

function cookie_header($cookies) {
	if(!$cookies) { return }

	$vals = $cookies.psobject.properties | % {
		"$($_.name)=$($_.value)"
	}

	[string]::join(';', $vals)
}

function is_in_dir($dir, $check) {
	$check = "$(fullpath $check)"
	$dir = "$(fullpath $dir)"
	$check -match "^$([regex]::escape("$dir"))(\\|`$)"
}

# hashes
function hash_for_url($manifest, $url, $arch) {
	$hashes = @(hash $manifest $arch) | ? { $_ -ne $null };

	if($hashes.length -eq 0) { return $null }

	$urls = @(url $manifest $arch)

	$index = [array]::indexof($urls, $url)
	if($index -eq -1) { abort "couldn't find hash in manifest for $url" }

	@($hashes)[$index]
}

# returns (ok, err)
function check_hash($file, $url, $manifest, $arch) {
	$hash = hash_for_url $manifest $url $arch
	if(!$hash) {
		warn "warning: no hash in manifest. sha256 is:`n$(compute_hash (fullpath $file) 'sha256')"
		return $true
	}

	write-host "checking hash..." -nonewline
	$type, $expected = $hash.split(':')
	if(!$expected) {
		# no type specified, assume sha256
		$type, $expected = 'sha256', $type
	}

	if(@('md5','sha1','sha256') -notcontains $type) {
		return $false, "hash type $type isn't supported"
	}

	$actual = compute_hash (fullpath $file) $type

	if($actual -ne $expected) {
		return $false, "hash check failed for $url. expected: $($expected), actual: $($actual)!"
	}
	write-host "ok"
	return $true
}

function compute_hash($file, $algname) {
	$alg = [system.security.cryptography.hashalgorithm]::create($algname)
	$fs = [system.io.file]::openread($file)
	try {
		$hexbytes = $alg.computehash($fs) | % { $_.tostring('x2') }
		[string]::join('', $hexbytes)
	} finally {
		$fs.dispose()
		$alg.dispose()
	}
}

function cmd_available($cmd) {
	try { gcm $cmd -ea stop } catch { return $false }
	$true
}

# for dealing with installers
function args($config, $dir) {
	if($config) { return $config | % { (format $_ @{'dir'=$dir}) } }
	@()
}

function run($exe, $arg, $msg, $continue_exit_codes) {
	if($msg) { write-host $msg -nonewline }
	try {
		$proc = start-process $exe -wait -ea stop -passthru -arg $arg
		if($proc.exitcode -ne 0) {
			if($continue_exit_codes -and ($continue_exit_codes.containskey($proc.exitcode))) {
				warn $continue_exit_codes[$proc.exitcode]
				return $true
			}
			write-host "exit code was $($proc.exitcode)"; return $false
		}
	} catch {
		write-host -f darkred $_.exception.tostring()
		return $false
	}
	if($msg) { write-host "done" }
	return $true
}

function unpack_inno($fname, $manifest, $dir) {
	if(!$manifest.innosetup) { return }

	write-host "unpacking innosetup..." -nonewline
	innounp -x -d"$dir\_scoop_unpack" "$dir\$fname" > "$dir\innounp.log"
	if($lastexitcode -ne 0) {
		abort "failed to unpack innosetup file. see $dir\innounp.log"
	}

	gci "$dir\_scoop_unpack\{app}" -r | mv -dest "$dir" -force

	rmdir -r -force "$dir\_scoop_unpack"

	rm "$dir\$fname"
	write-host "done"
}

function run_installer($fname, $manifest, $architecture, $dir) {
	# MSI or other installer
	$msi = msi $manifest $architecture
	$installer = installer $manifest $architecture

	if($msi) {
		install_msi $fname $dir $msi
	} elseif($installer) {
		install_prog $fname $dir $installer
	}
}

# deprecated (see also msi_installed)
function install_msi($fname, $dir, $msi) {
	$msifile = "$dir\$(coalesce $msi.file "$fname")"
	if(!(is_in_dir $dir $msifile)) {
		abort "error in manifest: MSI file $msifile is outside the app directory"
	}
	if(!($msi.code)) { abort "error in manifest: couldn't find MSI code"}
	if(msi_installed $msi.code) { abort "the MSI package is already installed on this system" }

	$logfile = "$dir\install.log"

	$arg = @("/i `"$msifile`"", '/norestart', "/lvp `"$logfile`"", "TARGETDIR=`"$dir`"",
		"INSTALLDIR=`"$dir`"") + @(args $msi.args $dir)

	if($msi.silent) { $arg += '/qn', 'ALLUSERS=2', 'MSIINSTALLPERUSER=1' }
	else { $arg += '/qb-!' }

	$continue_exit_codes = @{ 3010 = "a restart is required to complete installation" }

	$installed = run 'msiexec' $arg "running installer..." $continue_exit_codes
	if(!$installed) {
		abort "installation aborted. you might need to run 'scoop uninstall $app' before trying again."
	}
	rm $logfile
	rm $msifile
}

function extract_msi($path, $to) {
	$logfile = "$(split-path $path)\msi.log"
	$ok = run 'msiexec' @('/a', "`"$path`"", '/qn', "TARGETDIR=`"$to`"", "/lwe `"$logfile`"")
	if(!$ok) { abort "failed to extract files from $path.`nlog file: $(friendly_path $logfile)" }
	if(test-path $logfile) { rm $logfile }
}

# deprecated
# get-wmiobject win32_product is slow and checks integrity of each installed program,
# so this uses the [wmi] type accelerator instead
# http://blogs.technet.com/b/heyscriptingguy/archive/2011/12/14/use-powershell-to-find-and-uninstall-software.aspx
function msi_installed($code) {
	$path = "hklm:\software\microsoft\windows\currentversion\uninstall\$code"
	if(!(test-path $path)) { return $false }
	$key = gi $path
	$name = $key.getvalue('displayname')
	$version = $key.getvalue('displayversion')
	$classkey = "IdentifyingNumber=`"$code`",Name=`"$name`",Version=`"$version`""
	try { $wmi = [wmi]"Win32_Product.$classkey"; $true } catch { $false }
}

function install_prog($fname, $dir, $installer) {
	$prog = "$dir\$(coalesce $installer.file "$fname")"
	if(!(is_in_dir $dir $prog)) {
		abort "error in manifest: installer $prog is outside the app directory"
	}
	$arg = @(args $installer.args $dir)

	if($prog.endswith('.ps1')) {
		& $prog @arg
	} else {
		$installed = run $prog $arg "running installer..."
		if(!$installed) {
			abort "installation aborted. you might need to run 'scoop uninstall $app' before trying again."
		}
		rm $prog
	}
}

function run_uninstaller($manifest, $architecture, $dir) {
	$msi = msi $manifest $architecture
	$uninstaller = uninstaller $manifest $architecture

	if($msi -or $uninstaller) {
		$exe = $null; $arg = $null; $continue_exit_codes = @{}

		if($msi) {
			$code = $msi.code
			$exe = "msiexec";
			$arg = @("/norestart", "/x $code")
			if($msi.silent) {
				$arg += '/qn', 'ALLUSERS=2', 'MSIINSTALLPERUSER=1'
			} else {
				$arg += '/qb-!'
			}

			$continue_exit_codes.1605 = 'not installed, skipping'
			$continue_exit_codes.3010 = 'restart required'
		} elseif($uninstaller) {
			$exe = "$dir\$($uninstaller.file)"
			$arg = args $uninstaller.args
			if(!(is_in_dir $dir $exe)) {
				warn "error in manifest: installer $exe is outside the app directory, skipping"
				$exe = $null;
			} elseif(!(test-path $exe)) {
				warn "uninstaller $exe is missing, skipping"
				$exe = $null;
			}
		}

		if($exe) {
			$uninstalled = run $exe $arg "running uninstaller..." $continue_exit_codes
			if(!$uninstalled) { abort "uninstallation aborted."	}
		}
	}
}

# get target, name, arguments for shim
function shim_def($item) {
	if($item -is [array]) { return $item }
	return $item, (strip_ext (fname $item)), $null
}

function create_shims($manifest, $dir, $global) {
	$manifest.bin | ?{ $_ -ne $null } | % {
		$target, $name, $arg = shim_def $_
		echo "creating shim for $name"

		# check valid bin
		$bin = "$dir\$target"
		if(!(is_in_dir $dir $bin)) {
			abort "error in manifest: bin '$target' is outside the app directory"
		}
		if(!(test-path $bin)) { abort "can't shim $target`: file doesn't exist"}

		shim "$dir\$target" $global $name $arg
	}
}

function rm_shim($name, $shimdir) {
	$shim = "$shimdir\$name.ps1"

	if(!(test-path $shim)) { # handle no shim from failed install
		warn "shim for $name is missing, skipping"
	} else {
		echo "removing shim for $name"
		rm $shim
	}

	# other shim types might be present
	'.exe', '.shim', '.cmd' | % {
		if(test-path "$shimdir\$name$_") { rm "$shimdir\$name$_" }
	}	
}

function rm_shims($manifest, $global) {
	$manifest.bin | ?{ $_ -ne $null } | % {
		$target, $name, $null = shim_def $_
		$shimdir = shimdir $global
		
		rm_shim $name $shimdir
	}
}

# to undo after installers add to path so that scoop manifest can keep track of this instead
function ensure_install_dir_not_in_path($dir, $global) {
	$path = (env 'path' $global)

	$fixed, $removed = find_dir_or_subdir $path "$dir"
	if($removed) {
		$removed | % { "installer added $(friendly_path $_) to path, removing"}
		env 'path' $global $fixed
	}

	if(!$global) {
		$fixed, $removed = find_dir_or_subdir (env 'path' $true) "$dir"
		if($removed) {
			$removed | % { warn "installer added $_ to system path: you might want to remove this manually (requires admin permission)"}
		}
	}
}

function find_dir_or_subdir($path, $dir) {
	$dir = $dir.trimend('\')
	$fixed = @()
	$removed = @()
	$path.split(';') | % {
		if($_) {
			if(($_ -eq $dir) -or ($_ -like "$dir\*")) { $removed += $_ }
			else { $fixed += $_ }
		}
	}
	return [string]::join(';', $fixed), $removed
}

function env_add_path($manifest, $dir, $global) {
	$manifest.env_add_path | ? { $_ } | % {
		$path_dir = "$dir\$($_)"
		if(!(is_in_dir $dir $path_dir)) {
			abort "error in manifest: env_add_path '$_' is outside the app directory"
		}
		add_first_in_path $path_dir $global
	}
}

function add_first_in_path($dir, $global) {
	$dir = fullpath $dir

	# future sessions
	$null, $currpath = strip_path (env 'path' $global) $dir
	env 'path' $global "$dir;$currpath"

	# this session
	$null, $env:path = strip_path $env:path $dir
	$env:path = "$dir;$env:path"
}

function env_rm_path($manifest, $dir, $global) {
	# remove from path
	$manifest.env_add_path | ? { $_ } | % {
		$path_dir = "$dir\$($_)"
		remove_from_path $path_dir $global
	}
}

function env_set($manifest, $dir, $global) {
	if($manifest.env_set) {
		$manifest.env_set | gm -member noteproperty | % {
			$name = $_.name;
			$val = format $manifest.env_set.$($_.name) @{ "dir" = $dir }
			env $name $global $val
			sc env:\$name $val
		}
	}
}
function env_rm($manifest, $global) {
	if($manifest.env_set) {
		$manifest.env_set | gm -member noteproperty | % {
			$name = $_.name
			env $name $global $null
			if(test-path env:\$name) { rm env:\$name }
		}
	}
}

function pre_install($manifest) {
	$manifest.pre_install | ? { $_ } | % {
		echo "running pre-install script..."
		iex $_
	}
}

function post_install($manifest) {
	$manifest.post_install | ? { $_ } | % {
		echo "running post-install script..."
		iex $_
	}
}

function show_notes($manifest) {
	if($manifest.notes) {
		echo "Notes"
		echo "-----"
		echo (wraptext $manifest.notes)
	}
}

function all_installed($apps, $global) {
	$apps | ? { installed $_ $global }
}

function prune_installed($apps) {
	$installed = @(all_installed $apps $true) + @(all_installed $apps $false)
	$apps | ? { $installed -notcontains $_ }
}

# check whether the app failed to install
function failed($app, $global) {
	$ver = current_version $app $global
	if(!$ver) { return $false }
	$info = install_info $app $ver $global
	if(!$info) { return $true }
	return $false
}

function ensure_none_failed($apps, $global) {
	foreach($app in $apps) {
		if(failed $app $global) {
			abort "$app install failed previously. please uninstall it and try again."
		}
	}
}

# travelling directories have their contents moved from
# $from to $to when the app is updated.
# any files or directories that already exist in $to are skipped
function travel_dir($from, $to) {
	$skip_dirs = ls $to -dir | % { "`"$from\$_`"" }
	$skip_files = ls $to -file | % { "`"$from\$_`"" }

	robocopy $from $to /s /move /xd $skip_dirs /xf $skip_files > $null
}