An "immature boy" forced his way into a house and attacked a man with a metal bar and a kitchen knife accusing him of having sex with his girlfriend, a court has heard.

Jack Stead beat his victim with the bar as he lay in bed and tried to stab him in the throat with the blade. He also assaulted the man's parents who were downstairs in the property.

At the time of carrying out the house invasion the defendant was on two sets of police bail – one for Class A drug dealing and one for being involved in a brawl in the street. Sending the 20-year-old down a judge described his behaviour as "completely outrageous".

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Swansea Crown Court heard that the drugs offences come to light on June 17 last year when police went to a house in the Plasmarl area of Swansea looking for another individual. Craig Jones, prosecuting, said the officers found Stead in the bathroom of the Plasmarl Terrace property with a bag containing wraps of heroin and cocaine with a value of more than £1,100 along with a quantity of "cutting agent" used to bulk out the drugs when sold. An examination of the defendant's two mobile phones found messages showing he had been involved in supply of heroin, cocaine, and cannabis. The defendant was arrested, gave a "no comment" interview to officers, and was released on bail.

The court heard he came to the attention of police again on the evening of July 11 when he was involved in a brawl in Mumbles which saw him and a man by the name of Ryan Owen attack a group of youngsters on the street. One of the victims of the incident was left needing stitches to a cut on his head while others suffered bruises and swollen eyes. The prosecutor said though the scuffle had been short-lived it had been "an ugly incident in a public place". The defendant was again arrested and then released on bail.

The third incident took place on the morning of February 28 this year at a house in West Cross, Swansea.

Mr Jones said that around 8.20am Stead began banging on the door of a property in Green Bank Road and was demanding to speak to a man called Josh Byrne. When the door was opened by Mr Byrne's father the defendant – who was armed with a knife and metal bar – forced his way inside the property and made his way upstairs. Once in Mr Byrne's bedroom Stead accused his victim of sleeping with his girlfriend before attacking him by beating him to the legs with the bar, punching him in the face, and trying to stab him. Mr Byrne was able to wrap himself in his duvet to cushion some of the blows and he managed to parry the stabs. During the assault Stead was described as having a "white substance coming from his mouth".

By now the victim's father had armed himself with a wooden stick and struck Stead to the arm but his intervention was "laughed off". Stead then confronted Mr Byrne's mother, snatching her mobile from her and stamping on it as she tried to call the police, and then pushing her. He threatened to kill the mum if the police were called.

The court heard that the matter was, however, reported to police and when officers arrived Stead told them that he had been attacked and that Mr Byrne had slept with his girlfriend.

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Jack Davies Stead, of Cyprus Avenue, West Cross, Swansea, admitted possession of heroin and cocaine with intent to supply, being concerned in the supply of heroin, cocaine, and cannabis, affray, aggravated burglary, criminal damage, and two counts of assault by beating. He has no previous convictions but has police cautions for possession of amphetamine and being drunk and disorderly.

Hywel Davies, for Stead, said the defendant had begun as a user of drugs but then became involved in supply in order to pay off the debts he had accrue, and as far as the affray in Mumbles was concerned he had "stupidly" become involved in something he need not. The barrister described the events in West Cross as a "moment of madness" and said the defendant was still struggling to believe how foolish he had been.

Mr Davies said Stead was an "immature boy" who had turned to drugs to numb the pain of losing his father, grandfather, and brother – the last two to drug misuse – before his 16th birthday. He said drugs had then taken over the teenager's life and "he fell deeper and deeper into the darkness they bring".

He said while the defendant realised he would be spending much of his 20s in custody as a result of the offending, and that his convictions would limit the kind of careers he could pursue upon release, he was was interested in being a carpenter, plasterer, or other tradesman.

Judge Christopher Clee QC described Stead's behaviour at the West Cross house on the morning in question as " completely outrageous". The defendant was sentenced to a total of seven years detention – he will serve up to half that period in custody before being released on licence to serve the remainder in the community.

Ryan Lee Owen, aged 19, of Broughton Avenue, Portmead, Swansea, was sentenced to eight months detention suspended for two years and ordered to complete a rehabilitation course, 100 hours of unpaid work, and a 90-day alcohol abstinence monitoring requirement for his part in the Mumbles affray.

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