Have tol data in sqlite db, and add server script that accesses it

Adapt otol-data-converting script to generate otol.db, add server.py
script that provides access to that db, and adapt the app to query the
server for tol data when needed.

1 files changed, 142 insertions, 0 deletions

diff --git a/backend/server.py b/backend/server.py
new file mode 100755
index 0000000..2ff7e74
--- /dev/null
+++ b/backend/server.py
@@ -0,0 +1,142 @@
+#!/usr/bin/python3
+
+import sys, re, sqlite3, json
+from http.server import HTTPServer, BaseHTTPRequestHandler
+import urllib.parse
+
+hostname = "localhost"
+port = 8000
+dbFile = "data/otol.db"
+tolnodeReqDepth = 2
+	# For a /tolnode/name1 request, respond with name1's node, and descendent nodes in a subtree to some depth
+	# A depth of 0 means only respond with one node
+
+usageInfo =  f"usage: {sys.argv[0]}\n"
+usageInfo += "Starts a server that listens for GET requests to " + hostname + ":" + str(port) + "/tolnode/name1,\n"
+usageInfo += "and responds with JSON representing an object mapping names to node objects.\n"
+usageInfo += "Normally, the response includes node name1, and child nodes up to depth " + str(tolnodeReqDepth) + ".\n"
+usageInfo += "\n"
+usageInfo += "A query section ?type=type1 can be used to affect the result.\n"
+usageInfo += "If type1 is 'children', the operation acts on node name1's children, and the results combined.\n"
+usageInfo += "If type1 is 'chain', the response includes nodes from name1 up to the root, and their direct children.\n"
+
+dbCon = sqlite3.connect(dbFile)
+def lookupName(name):
+	cur = dbCon.cursor()
+	cur.execute("SELECT name, data FROM nodes WHERE name = ?", (name,))
+	row = cur.fetchone()
+	return row[1] if row != None else None
+#def lookupNameLike(name):
+#	cur = dbCon.cursor()
+#	found = False
+#	cur.execute("SELECT name, data FROM nodes WHERE name like ?", ("%{}%".format(name),))
+#	rows = cur.fetchall()
+#	if len(rows) == 0:
+#		return None
+#	else:
+#		jsonStr = "{"
+#		for i in range(len(rows)):
+#			jsonStr += json.dumps(rows[i][0]) + ":" + rows[i][1]
+#			if i < len(njList) - 1:
+#				jsonStr += ","
+#		jsonStr += "}"
+#		return jsonFromNameJsonList(rows)
+
+class DbServer(BaseHTTPRequestHandler):
+	def do_GET(self):
+		# Parse URL
+		urlParts = urllib.parse.urlparse(self.path)
+		path = urllib.parse.unquote(urlParts.path)
+		queryDict = urllib.parse.parse_qs(urlParts.query)
+		# Check first element of path
+		match = re.match(r"/([^/]+)/(.+)", path)
+		if match != None:
+			reqType = match.group(1)
+			if reqType == "tolnode":
+				name = match.group(2)
+				# Check query string
+				if "type" not in queryDict:
+					nodeJson = lookupName(name)
+					if nodeJson != None:
+						results = []
+						getResultsUntilDepth(name, nodeJson, tolnodeReqDepth, results)
+						self.respondJson(nodeResultsToJSON(results))
+						return
+				elif queryDict["type"][0] == "children":
+					nodeJson = lookupName(name)
+					if nodeJson != None:
+						obj = json.loads(nodeJson)
+						results = []
+						for childName in obj["children"]:
+							nodeJson = lookupName(childName)
+							if nodeJson != None:
+								getResultsUntilDepth(childName, nodeJson, tolnodeReqDepth, results)
+						self.respondJson(nodeResultsToJSON(results))
+						return
+				elif queryDict["type"][0] == "chain":
+					results = []
+					ranOnce = False
+					while True:
+						jsonResult = lookupName(name)
+						if jsonResult == None:
+							if ranOnce:
+								print("ERROR: Parent-chain node {} not found".format(name), file=sys.stderr)
+							break
+						results.append([name, jsonResult])
+						obj = json.loads(jsonResult)
+						# Add children
+						if not ranOnce:
+							ranOnce = True
+						else:
+							internalFail = False
+							for childName in obj["children"]:
+								jsonResult = lookupName(childName)
+								if jsonResult == None:
+									print("ERROR: Parent-chain-child node {} not found".format(name), file=sys.stderr)
+									internalFail = True
+									break
+								results.append([childName, jsonResult])
+							if internalFail:
+								break
+						# Check if root
+						if obj["parent"] == None:
+							self.respondJson(nodeResultsToJSON(results))
+							return
+						else:
+							name = obj["parent"]
+		self.send_response(404)
+		self.end_headers()
+		self.end_headers()
+	def respondJson(self, jsonStr):
+		self.send_response(200)
+		self.send_header("Content-type", "application/json")
+		self.end_headers()
+		self.wfile.write(jsonStr.encode("utf-8"))
+def getResultsUntilDepth(name, nodeJson, depth, results):
+	"""Given a node [name, nodeJson] pair, adds child node pairs to 'results', up until 'depth'"""
+	results.append([name, nodeJson])
+	if depth > 0:
+		obj = json.loads(nodeJson)
+		for childName in obj["children"]:
+			childJson = lookupName(childName)
+			if childJson != None:
+				getResultsUntilDepth(childName, childJson, depth-1, results)
+def nodeResultsToJSON(results):
+	"""Given a list of [name, nodeJson] pairs, returns a representative JSON string"""
+	jsonStr = "{"
+	for i in range(len(results)):
+		jsonStr += json.dumps(results[i][0]) + ":" + results[i][1]
+		if i < len(results) - 1:
+			jsonStr += ","
+	jsonStr += "}"
+	return jsonStr
+
+server = HTTPServer((hostname, port), DbServer)
+print("Server started at http://{}:{}".format(hostname, port))
+try:
+	server.serve_forever()
+except KeyboardInterrupt:
+	pass
+server.server_close()
+dbCon.close()
+print("Server stopped")