{- git-annex command
 -
 - Copyright 2024 Joey Hess <id@joeyh.name>
 -
 - Licensed under the GNU AGPL version 3 or higher.
 -}

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE OverloadedStrings #-}

module Command.P2PHttp where

import Command hiding (jobsOption)
import P2P.Http.Server
import P2P.Http.Url
import qualified P2P.Protocol as P2P
import Utility.Env
import Annex.UUID
import qualified Git
import qualified Git.Construct
import qualified Annex
import Types.Concurrency

import Servant
import qualified Network.Wai.Handler.Warp as Warp
import qualified Network.Wai.Handler.WarpTLS as Warp
import Network.Socket (PortNumber)
import qualified Data.Map as M
import Data.String
import Control.Concurrent.STM

cmd :: Command
cmd = noMessages $ dontCheck repoExists $ 
	noRepo (startIO <$$> optParser) $
		command "p2phttp" SectionPlumbing
			"communicate in P2P protocol over http"
			paramNothing (startAnnex <$$> optParser)

data Options = Options
	{ portOption :: Maybe PortNumber
	, bindOption :: Maybe String
	, certFileOption :: Maybe FilePath
	, privateKeyFileOption :: Maybe FilePath
	, chainFileOption :: [FilePath]
	, authEnvOption :: Bool
	, authEnvHttpOption :: Bool
	, unauthReadOnlyOption :: Bool
	, unauthAppendOnlyOption :: Bool
	, unauthNoLockingOption :: Bool
	, wideOpenOption :: Bool
	, proxyConnectionsOption :: Maybe Integer
	, jobsOption :: Maybe Concurrency
	, clusterJobsOption :: Maybe Int
	, directoryOption :: [FilePath]
	}

optParser :: CmdParamsDesc -> Parser Options
optParser _ = Options
	<$> optional (option auto
		( long "port" <> metavar paramNumber
		<> help "specify port to listen on"
		))
	<*> optional (strOption
		( long "bind" <> metavar paramAddress
		<> help "specify address to bind to"
		))
	<*> optional (strOption
		( long "certfile" <> metavar paramFile
		<> help "TLS certificate file for HTTPS"
		))
	<*> optional (strOption
		( long "privatekeyfile" <> metavar paramFile
		<> help "TLS private key file for HTTPS"
		))
	<*> many (strOption
		( long "chainfile" <> metavar paramFile
		<> help "TLS chain file"
		))
	<*> switch
		( long "authenv"
		<> help "authenticate users from environment (https only)"
		)
	<*> switch
		( long "authenv-http"
		<> help "authenticate users from environment (including http)"
		)
	<*> switch
		( long "unauth-readonly"
		<> help "allow unauthenticated users to read the repository"
		)
	<*> switch
		( long "unauth-appendonly"
		<> help "allow unauthenticated users to read and append to the repository"
		)
	<*> switch
		( long "unauth-nolocking"
		<> help "prevent unauthenticated users from locking content in the repository"
		)
	<*> switch
		( long "wideopen"
		<> help "give unauthenticated users full read+write access"
		)
	<*> optional (option auto
		( long "proxyconnections" <> metavar paramNumber
		<> help "maximum number of idle connections when proxying"
		))
	<*> optional jobsOptionParser
	<*> optional (option auto
		( long "clusterjobs" <> metavar paramNumber
		<> help "number of concurrent node accesses per connection"
		))
	<*> many (strOption
		( long "directory" <> metavar paramPath
		<> help "serve repositories in subdirectories of a directory"
		))

startAnnex :: Options -> Annex ()
startAnnex o
	| null (directoryOption o) = ifM ((/=) NoUUID <$> getUUID)
		( do
			authenv <- liftIO getAuthEnv
			st <- mkServerState o authenv
			liftIO $ runServer o st
		-- Run in a git repository that is not a git-annex repository.
		, liftIO $ startIO o 
		)
	| otherwise = liftIO $ startIO o

startIO :: Options -> IO ()
startIO o
	| null (directoryOption o) = 
		giveup "Use the --directory option to specify which git-annex repositories to serve."
	| otherwise = do
		authenv <- getAuthEnv
		st <- mkst authenv mempty
		runServer o st
  where
	mkst authenv oldst = do
		repos <- findRepos o
		sts <- forM repos $ \r -> do
			strd <- Annex.new r
			Annex.eval strd (mkstannex authenv oldst)
		return (mconcat sts)
			{ updateRepos = updaterepos authenv
			}
	
	mkstannex authenv oldst = do
		u <- getUUID
		if u == NoUUID
			then return mempty
			else case M.lookup u (servedRepos oldst) of
				Nothing -> mkServerState o authenv
				Just old -> return $ P2PHttpServerState
					{ servedRepos = M.singleton u old
					, serverShutdownCleanup = mempty
					, updateRepos = mempty
					}
	
	updaterepos authenv oldst = do
		newst <- mkst authenv oldst
		return $ newst
			{ serverShutdownCleanup = 
				serverShutdownCleanup newst 
					<> serverShutdownCleanup oldst
			}

runServer :: Options -> P2PHttpServerState -> IO ()
runServer o mst = go `finally` serverShutdownCleanup mst
  where
	go = do
		let settings = Warp.setPort port $ Warp.setHost host $
			Warp.defaultSettings
		mstv <- newTMVarIO mst
		case (certFileOption o, privateKeyFileOption o) of
			(Nothing, Nothing) -> Warp.runSettings settings (p2pHttpApp mstv)
			(Just certfile, Just privatekeyfile) -> do
				let tlssettings = Warp.tlsSettingsChain
					certfile (chainFileOption o) privatekeyfile
				Warp.runTLS tlssettings settings (p2pHttpApp mstv)
			_ -> giveup "You must use both --certfile and --privatekeyfile options to enable HTTPS."
	port = maybe
		(fromIntegral defaultP2PHttpProtocolPort)
		fromIntegral
		(portOption o)
	host = maybe
		(fromString "*") -- both ipv4 and ipv6
		fromString
		(bindOption o)

mkServerState :: Options -> M.Map Auth P2P.ServerMode -> Annex P2PHttpServerState
mkServerState o authenv = 
	withAnnexWorkerPool (jobsOption o) $
		mkP2PHttpServerState
			(mkGetServerMode authenv o)
			return
			(fromMaybe 1 $ proxyConnectionsOption o)
			(fromMaybe 1 $ clusterJobsOption o)

mkGetServerMode :: M.Map Auth P2P.ServerMode -> Options -> GetServerMode
mkGetServerMode _ o _ Nothing
	| wideOpenOption o = ServerMode
		{ serverMode = P2P.ServeReadWrite
		, unauthenticatedLockingAllowed = unauthlock
		, authenticationAllowed = False 
		}
	| unauthAppendOnlyOption o = ServerMode 
		{ serverMode = P2P.ServeAppendOnly
		, unauthenticatedLockingAllowed = unauthlock
		, authenticationAllowed = canauth
		}
	| unauthReadOnlyOption o = ServerMode
		{ serverMode = P2P.ServeReadOnly
		, unauthenticatedLockingAllowed = unauthlock
		, authenticationAllowed = canauth
		}
	| otherwise = CannotServeRequests
  where
	canauth = authEnvOption o || authEnvHttpOption o
	unauthlock = not (unauthNoLockingOption o)
mkGetServerMode authenv o issecure (Just auth) =
	case (issecure, authEnvOption o, authEnvHttpOption o) of
		(Secure, True, _) -> checkauth
		(NotSecure, _, True) -> checkauth
		_ -> noauth
  where
	checkauth = case M.lookup auth authenv of
		Just servermode -> ServerMode 
			{ serverMode = servermode
			, authenticationAllowed = False
			, unauthenticatedLockingAllowed = False
			}
		Nothing -> noauth
	noauth = mkGetServerMode authenv noautho issecure Nothing
	noautho = o { authEnvOption = False, authEnvHttpOption = False }

getAuthEnv :: IO (M.Map Auth P2P.ServerMode)
getAuthEnv = do
	environ <- getEnvironment
	let permmap = M.fromList (mapMaybe parseperms environ)
	return $ M.fromList $
		map (addperms permmap) $
			mapMaybe parseusername environ
  where
	parseperms (k, v) = case deprefix "GIT_ANNEX_P2PHTTP_PERMISSIONS_" k of
		Nothing -> Nothing
		Just username -> case v of
			"readonly" -> Just
				(encodeBS username, P2P.ServeReadOnly)
			"appendonly" -> Just
				(encodeBS username, P2P.ServeAppendOnly)
			_ -> Nothing

	parseusername (k, v) = case deprefix "GIT_ANNEX_P2PHTTP_PASSWORD_" k of
		Nothing -> Nothing
		Just username -> Just $ Auth (encodeBS username) (encodeBS v)

	deprefix prefix s
		| prefix `isPrefixOf` s = Just (drop (length prefix) s)
		| otherwise = Nothing

	addperms permmap auth@(Auth user _) = 
		case M.lookup user permmap of
			Nothing -> (auth, P2P.ServeReadWrite)
			Just perms -> (auth, perms)

findRepos :: Options -> IO [Git.Repo]
findRepos o = do
	files <- concat
		<$> mapM (dirContents . toOsPath) (directoryOption o)
	map Git.Construct.newFrom . catMaybes 
		<$> mapM Git.Construct.checkForRepo files