differ.coffee

fs = require 'fs'
XXHash = require 'xxhash'
path = require 'path'
#dive = require 'dive'
HashStream = XXHash.Stream
c = console
startTime = Date.now()

mapFileName = 'pbix.json'
rootDir = '../pbix'

computeDirXXHashes = (rootDir, callback) ->
	fileMap = {}
	fileCount = 0
	hashCount = 0
	rootDir = fs.realpathSync(rootDir)

	onFile = (err, path) ->
		if err then return
		fileCount += 1
		hasher = new HashStream(0xDEAD, 64, 'hex')
		
		fs.createReadStream(path).pipe(hasher).on 'finish', ->
			hash = hasher.read()
			path = path.substr(rootDir.length)
			fileMap[path] = hash
			hashCount += 1
			
			if fileCount == hashCount
				 callback(fileMap)

	onComplete = ->
		elapsed = Date.now() - startTime	
		c.log 'elapsed', elapsed, "fileCount", fileCount
		
	dive rootDir, onFile, onComplete 

xxFileHash = (path, callback) ->
	hasher = new HashStream(0xDEAD, 64, 'hex')
	fs.createReadStream(path).pipe(hasher).on 'finish', ->
			hash = hasher.read()
			callback(hash)

isEqual = (oldObj, newObj) ->
	if oldObj == newObj then return true
	for key of oldObj
		if oldObj[key] != newObj[key] then return false
	return true

getMapDiff = (oldMap, newMap) ->
	changed = []
	added = []
	removed = []

	for filePath of newMap
		if oldMap.hasOwnProperty(filePath)
			if not isEqual(oldMap[filePath], newMap[filePath])
				changed.push(filePath)
			delete oldMap[filePath]
			delete newMap[filePath]
		else
			added.push(filePath)

	for filePath of oldMap
		removed.push(filePath)

	return {added: added, changed:changed, removed:removed}


dirStats = (rootDir, opts = {}, callback) ->
	recursive = if opts.recursive!=undefined then opts.recursive else true;
	files = opts.files || true;
	directories = opts.directories || false;

	statsMap = {}
	realRootDir = fs.realpathSync(rootDir)
	todo = 0
	totalSize = 0
	startTime = Date.now()

	dive = (dir) ->
		todo++
		fs.readdir dir, (err, list) ->
			--todo
			if err then return

			list.forEach (file) ->
				fullPath = path.resolve(dir, file)
				todo++

				fs.lstat fullPath, (err, stat) ->
					todo--
					if err then return
					relativePath = fullPath.substr(realRootDir.length)
					statObj = 
						lastmod: stat.mtime.getTime()
						size: stat.size

					totalSize += stat.size

					if stat.isDirectory()
						if file[0] == '.' then return
						if directories then statsMap[relativePath] = statObj
						if recursive then dive(fullPath)
					else if stat.isFile()
						if files then statsMap[relativePath] = statObj

					if todo == 0
						elapsed = Date.now() - startTime
						files = Object.keys(statsMap).length
						console.log "elapsed", elapsed, "files", files, "size", totalSize
						if callback then callback(statsMap)
						#console.log statsMap
				return

			return
		return

	dive(rootDir)
	return

mapFileName = 'pbix.json'
rootDir = '../pbix'

# computeDirXXHashes '../pbix', (newMap) ->
# 	oldMap = JSON.parse(fs.readFileSync(mapFileName, 'utf-8'))
# 	fs.writeFile mapFileName, JSON.stringify(newMap, null, '\t'), -> 
# 		c.log "written elapsed", Date.now() - startTime

# 	diffs = getMapDiff(oldMap, newMap)
# 	c.log diffs

computeHashes = (filePaths, rootDir, callback) ->
	todo = 0
	for filePath in filePaths
		todo++
		xxFileHash rootDir + filePath, (hash) ->
			todo--
			hashCache[filePath] = hash
			if todo == 0 then callback() 

	if todo == 0 then callback()

hashCache = {}
hashCacheFile = 'hashCache.json'
if fs.exists('hashCache.json')
	hashCache = JSON.parse(fs.readFileSync(hashCacheFile, 'utf-8'))


dirStats rootDir, recursive:true, (newStatsMap) ->
	oldStatsMap = JSON.parse(fs.readFileSync(mapFileName, 'utf-8'))
	fs.writeFile mapFileName, JSON.stringify(newStatsMap, null, '\t')
	diffs = getMapDiff(oldStatsMap, newStatsMap)

	computeHashes diffs.changed, rootDir, ->
		fs.writeFile hashCacheFile, JSON.stringify(hashCache, null, '\t')

	c.log diffs

# watcher = fs.watch rootDir, recursive:true, (event, filename) ->
# 	c.log "watch", event, filename