Were AR15's legal?

Can you explain this to me? I thought that in general, AR15's were not allowed in California (possibly unless bought prior to 1989?) -- yet the media are reporting that the AR15's used yesterday were "legally purchased" 3 or 4 years ago....

Am I confused about California law?
Are there significant numbers of some form of AR15 that can be purchased legally in California?

I don't live there so I'm not as familiar and don't want to say something stupd in discussions with familyl

Any person who, within this state, manufactures or causes to be manufactured, distributes, transports, or imports into the state, keeps for sale, or offers or exposes for sale, or who gives or lends any assault weapon or any .50 BMG rifle, except as provided by this chapter, is guilty of a felony, and upon conviction shall be punished by imprisonment pursuant to subdivision (h) of Section 1170 for four, six, or eight years.”

Doesn't look to me that you can legally possess a typical AR15 in california, based on the above law.....I'm not a californian, so I'm just googling to try and understand their laws.....

Think this may be pertinent:

30605. (a) Any person who, within this state, possesses any assault
weapon, except as provided in this chapter, shall be punished by
imprisonment in a county jail for a period not exceeding one year, or
by imprisonment pursuant to subdivision (h) of Section 1170.
(b) Notwithstanding subdivision (a), a first violation of these
provisions is punishable by a fine not exceeding five hundred dollars
($500) if the person was found in possession of no more than two
firearms in compliance with Section 30945 and the person meets all of
the following conditions:
(1) The person proves that he or she lawfully possessed the
assault weapon prior to the date it was defined as an assault weapon.
(2) The person has not previously been convicted of a violation of
this article.
(3) The person was found to be in possession of the assault weapon
within one year following the end of the one-year registration
period established pursuant to Section 30900.
(4) The person relinquished the firearm pursuant to Section 31100,
in which case the assault weapon shall be destroyed pursuant to
Sections 18000 and 18005.
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This makes it look highly illegal to POSSESS the type rifle the media are saying was "purchased legally"......it sounds to me that it would be more correct to say, "purchased legally and imported, lent, and possessed illegally"

Unless I don't understand some exception somewhere....