print ("normal command to list databases");
printjson(db.adminCommand({listDatabases: 1 }) );

print ("");
print ("Make variable saving the output.");
db_list = db.adminCommand({listDatabases: 1 });

print ("");
print ("Print out a better list of databases.");
db_list['databases'].forEach( function(db)
       { print( "database: " + db.name ); }
     )   ;

print ("");
print ("Make database test1 if it does not exist.");

db = db.getSiblingDB('test1');

print ("");
db.testdoc.drop();

print ("");
print ("create fuction to print out testdoc.")

function print_test_doc() {
  print ("printing testdoc orders by color");
  result = db.testdoc.find().sort({color : 1})
  result.forEach( function(p)
    { print( "person: " + p.person + ", color : " + p.color + ", pencils : " + p.pencils  );});

}

print ("Insert two documents, create collection.");
db.testdoc.insertOne({ person:"mark", color: "red", pencils : 10});
db.testdoc.insertOne({ person:"john", color: "blue", pencils : 20});
db.testdoc.insertOne({ person:"heidi", color: "purple", pencils : 30});
db.testdoc.insertOne({ person:"collin", color: "black", pencils : 40});
db.testdoc.insertOne({ person:"tristan", color: "red", pencils : 50});

print ("");
print ("update one row, with UpdateOne, red to 100 pencils");
db.testdoc.updateOne({color:"red"}, { $set: { pencils: 100 }} );
print_test_doc()

print ("");
print ("update one row with update, red to 200 pecncils");
db.testdoc.update({color:"red"}, { $set: { pencils: 200 }});
print_test_doc()

print ("");
print ("update many rows, all red to 300 pencils");
db.testdoc.update({color:"red"}, { $set: { pencils:300 }}, {multi : 1 });
print_test_doc()

print ("");
print ("removes john");
db.testdoc.findAndModify({query : {person:"john"}, remove: 1 });
print_test_doc()

print ("");
print ("adds john with findAndModify");
db.testdoc.findAndModify({query : {person : "john"}, update : { person : "john",  color: "blue", pencils : 20}, upsert: true });
print_test_doc()


print ("");
print ("adds john2 with update");
db.testdoc.update({person : "john2"}, {$set : {color: "blue", pencils : 400} } , {upsert: true });
print_test_doc()

print ("");
print ("increment pencils for all by 2, with update");
db.testdoc.update({}, { $inc: { pencils: 2 }}, {multi : 1});
print_test_doc()


print ("");
print ("increment pencils for all by 3, with updateMany");
db.testdoc.updateMany({}, { $inc: { pencils: 3 }});
print_test_doc()

print ("");
print ("Add 5 doc we will delete later.");
db.testdoc.insertOne({ person:"d1", color: "black", pencils : -5});
db.testdoc.insertOne({ person:"d2", color: "black", pencils : -4});
db.testdoc.insertOne({ person:"d3", color: "black", pencils : -3});
db.testdoc.insertOne({ person:"d4", color: "black", pencils : -2});
db.testdoc.insertOne({ person:"d5", color: "black", pencils : -1});
print_test_doc()

print ("");
print ("delete on doc with color black with deleteOne.");
db.testdoc.deleteOne({ color : "black"});
print_test_doc()

print ("");
print ("delete all with pencils less than -2 with deleteMany.");
db.testdoc.deleteMany({ pencils : { $lt : 0}});
print_test_doc()


print ("");
print ("insert person with a color array");
db.testdoc.insertOne({ person:"colors1", color: ["red", 'white'], pencils : 500});
print_test_doc()

print ("");
print ("print out people with color red, scalar or in array");
result = db.testdoc.find({color: 'red'}).sort({color : 1})
result.forEach( function(p)
  { print( "person: " + p.person + ", color : " + p.color + ", pencils : " + p.pencils  );});

print ("");
print ("print out people with color red or blue, using array");
result = db.testdoc.find({color: { $in : ['blue', 'red']}}).sort({color : 1})
result.forEach( function(p)
  { print( "person: " + p.person + ", color : " + p.color + ", pencils : " + p.pencils  );});

print ("");
print ("print out people with color red or blue, using or");
result = db.testdoc.find({ $or :  [ {color : 'blue'},{ color : 'red' }]}).sort({color : 1})
result.forEach( function(p)
  { print( "person: " + p.person + ", color : " + p.color + ", pencils : " + p.pencils  );});

print ("");
print ("print out people with color red, just the name");
result = db.testdoc.find({color : 'red'},{_id : 0, person : 1} ).sort({color : 1})
print(result)

print ("");
print ("print out people with color red, but the color field, by excluding color, limit 1");
result = db.testdoc.find({color : 'red'}, {color : 0} ).sort({color : 1}).limit(1)
print(result)

print ("");
print ("print out people with color red, but the color field, by including fields only, limit 1");
result = db.testdoc.find({color : 'red'}, {person : 1, pencils : 1} ).sort({color : 1}).limit(1)
print(result)


print ("");
print ("print out numberdocuments  with color red, using countDocuments");
result = db.testdoc.countDocuments({color : 'red'})
print(result)

print ("");
print ("print out numberdocuments  with color red, using find and count");
result = db.testdoc.find({color : 'red'}).count()
print(result)

print ("");
print ("print out no of red and blue pencils");
result = db.testdoc.aggregate([ {$match : {color : { $in : ['red', 'blue'] }}}, {$group : { _id : { c : '$color'} , p : {$sum : "$pencils"}}} ])
print(result)

print ("");
print ("print out no of red and blue pencils, sort highest penci;s and limit by 1, by aggregate");
result = db.testdoc.aggregate([ {$match : {color : { $in : ['red', 'blue'] }}}, {$group : { _id : { c : '$color'} , p : {$sum : "$pencils"}}}, {$sort : {p : -1}}, {$limit: 1},{$project :  {_id : 0, p : 1, color : "$_id.c"}}])
print(result)


db.temp1.drop()
db.temp2.drop()
print ("");
print ("print out no of red and blue pencils, sort highest pencils and limit by 1, by aggregate, but use find, sort, and limit separately");
result1 = db.testdoc.find({ color : { $in : ['red', 'blue'] } }).toArray()
db.temp1.insertMany( result1 )
result2 = db.temp1.aggregate([ {$group : { _id : { c : '$color'} , p : {$sum : "$pencils"}  }}, {$project :  {_id : 0, p : 1, color : "$_id.c"}} ]).toArray()
db.temp2.insertMany(result2 )
result3 = db.temp2.find({}, {_id:0}).sort({p : -1}).limit(1)
print(result3)

db.temp1.drop()
db.temp2.drop()
print ("");
print ("same as before, but use out in pipline to make temp document");
result1 = db.testdoc.find({ color : { $in : ['red', 'blue'] } }).toArray()
db.temp1.insertMany( result1 )
db.temp1.aggregate([ {$group : { _id : { c : '$color'} , p : {$sum : "$pencils"}  }}, {$project :  {_id : 0, p : 1, color : "$_id.c"}}, {$out : "temp2"} ])
result3 = db.temp2.find({}, {_id:0}).sort({p : -1}).limit(1)
print(result3)


print ("")
print ("Itentionally make an error. ")
try{
  result4 = result1.aggregate([ {$group : { _id : { c : '$color'}, p : {$sum : "$pencils"} }} ])
}
catch (err)
  { print ("ERRROR: can't treat results like a document. It has no functions. Save to document first") }

print ("")
print ("Make index, view indexes, run find, view plan of query ")
db.testdoc.createIndex({person : 1, color : 1})
db.testdoc.insertOne({ person:"john", color: "blue", pencils : 21});
result = db.testdoc.find({person : "john"}).sort({color : 1}) 
print (result)
result = db.textdoc.explain().find({person : "john"}).sort({color : 1})
print (result)

print ("")
print ("explain without using any indexes")
result = db.testdoc.explain().find({pencils : {$gte : 300 }}).sort({color : 1})
print (result)

print ("")
print ("explain with sort outside of index")
result = db.testdoc.explain().find({person : "john"}).sort({pencils : 1})
print (result)

print ("")
print ("view indexes, then drop, then view, create, view, drop again, view.")
result = db.testdoc.getIndexes()
print (result)
// key: { person: 1, color: 1 }, name: 'person_1_color_1'
db.testdoc.dropIndex({ person: 1, color: 1 })
result = db.testdoc.getIndexes()
print (result)
db.testdoc.createIndex({person : 1, color : 1})
result = db.testdoc.getIndexes()
print (result)
db.testdoc.dropIndex('person_1_color_1')
result = db.testdoc.getIndexes()
print (result)

print ("")
print ("create index on array and search it.")

db.testdoc.insertOne({ person:"array1", color: "blue", pencils : 21, a :[1,2,3,4]});
db.testdoc.insertOne({ person:"array2", color: "blue", pencils : 21, a : [4,5,6,7]});
db.testdoc.createIndex({a : 1})
result = db.testdoc.aggregate([ {$match : {a : 1}},{$project :  {_id : 0, person : 1, a : "$a"}}])
print(result)
result = db.testdoc.aggregate([ {$match : {a : 4}},{$project :  {_id : 0, person : 4, a : "$a"}}])
print(result)