Although the Iranians are using Russian components (if only because these are better than Chinese ones), they probably had technical assistance (for a price) from China. The Chinese have a lot of experience reverse engineering Russian warplanes, and developing variations. The Chinese are getting away from that, because they finally realized that all they ended up with was a lot of crap fighters. Now they are building a new air force with expensive, and high tech, fighters imported from Russia, or built under license.
The Iranians have become obsessed with these "propaganda weapons," where they hack something together from an existing Russian or American system, and proclaim it to be a "designed and manufactured in Iran." It's all rather pathetic, and it all began during the 1980s, when Iran and Iraq were fighting a nasty war. Some of the hacks worked, after a fashion. Iran created a longer range SCUD missile by the simple expedient of lengthening the missile with a larger fuel tank. This changed the flight characteristics of the missile, but since these things were being fired at city size (as in Baghdad) targets, it didn't matter. Actually, the Iranians didn't really need the longer range missiles, because Baghdad was pretty close to the Iranian border. Iran actually got the technology for these SCUD mods from North Korea, but Iranian press releases always touted the achievement as being the result of Iranian scientists and engineers. Also during the 1980s, Iran manufactured chemical weapons (mainly mustard gas). This was crude stuff, but the technology was fairly simple, and has gotten better in the last twenty years. However, Iran does not export any of its chemical weapons.
In the 1990s, Iran began building, or modifying, Russian armored vehicles. They also built a clone of the F-5E, calling it the Azarakhsh. The Iranians had dozens of damaged F-5s from their war with Iraq, and they reported that they had repaired, or rebuilt (into Azarakhsh) many of these.
Iran does have a large arms industry, and exports weapons to over fifty countries. But none of those fantasy weapons are exported. No, the stuff that is shipped to foreign customers largely consists of knockoffs of Russian and Chinese small arms, mortars and rockets. Iran also has a reputation of selling to anyone. If you have the cash, Iran will deliver, no questions asked.
Iran has shown off a modified American F-5 fighter and proclaimed this new "Saegheh" as similar to the American F-18 jet fighter. This is not the first time Iran has run a stunt like this. But even with a redesigned tail and better electronics, the 1960s era F-5 is still a low cost, and low performance, aircraft. The F-5E, which the Iranians had when the Islamic revolution took over in 1979, is an 11 ton aircraft, with a max speed of 1,700 kilometers an hour, and a range of some 1,400 kilometers. It was armed with two 20mm cannon, and could carry about three tons of missiles and bombs. The Iranians have taken the basic F-5 frame and rebuilt it to hold two Russian engines. The Chinese did the same thing, and produced the J-8 (a twin engine MiG-21) that turned out to be not worth the effort.