local mongo = require 'mongo'
local client = mongo.Client 'mongodb://127.0.0.1'
local collection = client:getCollection('lua-mongo-test', 'test')
collection:drop() -- Clear collection

-- Common variables
local id = mongo.ObjectID()
local query1 = mongo.BSON '{ "age" : { "$gt" : 25 } }'
local query2 = mongo.BSON { _id = id }

-- Store document
collection:insert { _id = id, name = 'John Smith', age = 50 }

-- Fetch document
local document = collection:findOne(query1):value()
print(document.name)

-- Iterate in a for-loop
for document in collection:find(query1):iterator() do
	print(document.name)
end

-- Implicit Lua/JSON to BSON conversion where BSON is required
collection:insert { integer = 123 }
collection:insert '{ "string" : "abc" }'

-- Use options in queries
print(collection:count({}, { skip = 1, limit = 2 }))

-- Access to BSON where needed
local bson = collection:findOne(query1)
print(bson) -- BSON is implicitly converted to JSON

-- Explicit BSON to Lua conversion
local value = bson:value()
print(value.name)

-- Transparently include BSON documents in other documents
collection:update(query2, { age = 60, backup = bson }) -- Update document
collection:remove(query2) -- Remove document

local bulk = collection:createBulkOperation()

-- Multiple insertions
bulk:insert { a = 1 }
bulk:insert { b = 2 }
bulk:insert { c = 3 }

-- Multiple modifications
bulk:replaceOne({ a = 1 }, { b = 1 })
bulk:updateMany('{}', '{ "$inc" : { "b" : 2 } }')
bulk:removeOne { c = 3 }

-- Execute all the queued operations
assert(bulk:execute())

local SimpleClass = {} -- Class metatable

local function SimpleObject(id, name) -- Constructor
	return setmetatable({
		id = id,
		name = name,
	}, SimpleClass)
end

function SimpleClass:__tostring() -- Method
	return tostring(self.id) .. ' --> ' .. self.name
end

function SimpleClass:__tobson() -- Called when object is packed into BSON
	return {
		_id = self.id,
		binary = mongo.Binary(self.name), -- Store 'name' as BSON Binary for example
	}
end

-- A root '__tobson' metamethod may return a table or BSON document.
-- A nested '__tobson' metamethod may return a Lua value, BSON type or BSON document.

-- BSON handler
local function handler(document)
	return SimpleObject(document._id, (document.binary:unpack()))
end

-- Anything callable can serve as a BSON handler. For instance, it can be a table or userdata
-- with a '__call' metamethod.

-- Note that the same handler will be called for each nested document. Thus, the handler should
-- be able to differentiate documents based on some internal criteria.

local object = SimpleObject(id, 'John Smith')
print(object)

-- Explicit BSON <-> Lua conversion
local bson = mongo.BSON(object)
local object = bson:value(handler)
print(object)

-- Store object
collection:insert(object)

-- Restore object
local object = collection:findOne(query2):value(handler)
print(object)

-- Iterate objects in a for-loop
for object in collection:find(query2):iterator(handler) do
	print(object)
end