Someone who takes an over-optimistic view of himself, his own country and all other things that have meaning/value to him. And who doesn't see or admit the smaller, yet not insignificant, things. E.g. as well in an attempt to win other people over of something or give them the impression of his own greatness (by leaving out whichever isn't going to benefit that impression he wants to make.)
Such a person is a partisan [OxfordDictionaries defines the adjective: prejudiced in favour of a particular cause: newspapers have become increasingly partisan] or even a bigot [U.D.: One who is narrowly or intolerantly devoted to his or her opinions and prejudices].
They are also narrow-minded, blinkered, and parochial.
One who wears rose-coloured glasses may be a useful expression.
What comes to mind is the expression see things through rose-colored glasses.
rose-colored glasses: with an attitude that things are better than they really are
Alternately, consider be in an ivory tower, have blinders on, and have a tin ear for.
ivory tower: an attitude of aloofness or disdain or disregard for worldly or practical affairs
have blinders on: to not be able to accept or recognize what's happening around you
a tin ear: an insensitivity to the appropriateness or subtlety of verbal expression
Which the good folks at http://dictionary.reference.com/browse/panglossian define as
a person who views a situation with unwarranted optimism
Depending on the context a person is either megalomaniac of narcissistic. Whereas the latter has a more negative connotation. Personally I rather be megalomaniac then narcissistic.
an attempt to win other people over of something or give them the impression of his own greatness
In this case the person is definitely narcissistic.
Someone who takes an over-optimistic view of himself, his own country and all other things that have meaning/value to him.
If the over-optimistic view isn't necessarily egoistically driven, I would go for megalomaniac
In the sense of my country (or culture) right or wrong (and there's nothing wrong, so there's no point bringing it up in the first place), either chauvinist or jingoist would fit, depending on whether it is merely objectionable or actually hostile/bellicose. It may even be safe to use the word chauvinist again outside of the sphere of "gender" relations¹, though that would have been nearly impossible in my youth.
While either term might naturally cause the hearer/reader to infer that the subject is also a self-satisfied blowhard git, it is at least theoretically possible for chauvinists to be narrowly modest about their own personal accomplishments, situations and possessions. It is therefore necessary to add something personal to the mix in order to avoid relying on inference.
¹ I truly hate using a term referring to grammatical categories when the correct word is sexual, but creeping euphemisms have done damage to the language that I fear is irreparable.