Federal charges have been unsealed againstChelsea bombing suspect Ahmad Rahami in a complaint that provides eerie new details behind the weekend terror attacks — including that he bought some of the bomb supplies on eBay.

Rahami, 28, is charged with four counts — use of weapons of mass destruction, bombing a place of public use, destruction of property by means of fire or explosive, and use of a destructive device during and in furtherance of a crime of violence, according to the complaint that was unsealed Tuesday in Manhattan federal court.

The complaint ups the total number of people injured in Saturday’s blast at 23rd Street and Sixth Avenue from 29 to 31, including a visitor from the United Kingdom.

Another undetonated bomb was found on 27th Street about four blocks away.

Court papers reveal that Rahami used eBay and the username “Ahmad Rahimi” to purchase several ingredients to make the shrapnel-laced pressure-cooker bombs.

He bought a 5-pound pack of citric acid, which is commonly used in “improvised explosives,” on Aug. 10 and shipped it to an unidentified business where he worked in Perth Amboy, New Jersey, the complaint says.

In July, he purchased a circuit board, “e-match” electric igniters — found in the 27th Street bomb — as well as hundreds of lead and steel balls, the papers say.

Prosecutors say Rahami listed two videos related to jihad anthems under his “favorites” list on YouTube, under the name “Yaafghankid78.”

He was also filmed on a video shot by a family member exploding a partially buried device on Sept. 15 — just two days before the Chelsea bombings.

“The video depicts the lighting of the fuse, a loud noise and flames, followed by billowing smoke and laughter,” the complaint says. “Rahami then enters the frame and is seen picking up the cylindrical container.”

Rahami was arrested Monday and charged with attempted murder after a violent shootout with police in Linden, New Jersey.

Cops recovered from him a handwritten journal detailing his alleged desire to carry out terrorist attacks, court papers say.

“You (USA Government) continue your [unintelligible] slaught[er] against the mujahidean be it Afghanistan, Iraq, Sham [Syria], Palestine,” he wrote.

Rahami also expressed concern about getting busted before being able to carry out a suicide attack.

“The F.B.I. & homeland security [unintelligible] looking for me [unintelligible] my heart I pray to the beautiful wise ALLAH. To not take JIHAD away from. I beg [unintelligible] for shahadat [martyrdom] & Inshallah [God willing] this call will be A[n]swered,” he wrote.

He also makes references to dead al Qaeda leader Anwar al-Awlaki, Fort Hood killer Nidal Hasan and “Brother Osama Bin Laden,” the papers say.

“Inshallah [God willing] the sounds of the bombs will be heard in the streets. Gun shots to your police. Death To Your OPPRESSION,” he wrote.

The journal was damaged in the shootout and some of it is unintelligible, the complaint says.

US Attorney Preet Bharara is the first to bring federal charges against the accused terrorist, who is expected to be charged by feds in New Jersey for setting several pipe bombs in Seaside Park and Elizabeth.

Rahami, who was born in Afghanistan and is a naturalized US citizen, faces up to life behind bars.