The unsuspecting victim, who was looking away from Turipa at the time, suffered a 15-centimetre gash parallel to his jaw and was permanently scarred.
He was lucky the police station was close by, said Judge David Ruth.
The victim, who spoke in court, said he would "not be here" if not for the response of emergency services.
He sometimes found it difficult to get out of bed.
He suffered from depression, had little trust in strangers and lived in fear of callous violence.
He felt bitter and cheated.
Judge Ruth said earlier that night Turipa had smashed a beer bottle outside a city bar and used it to threaten a bystander before security guards intervened.
Turipa later told police his victim was being cheeky and making racist remarks.
Judge Ruth said Turipa had a criminal record "littered with violence".
There was a troubling and escalating trend in his offending, which included convictions for assaulting women and one for assaulting police.
Judge Ruth said it was to Turipa's discredit that he was under the influence of substances during the "cowardly" attack.
Turipa had been remanded in custody since that night and knew a lengthy jail term was inevitable.
Crown prosecutor Josh Lucas said the attack was extreme violence resulting in a serious injury that had lasting effects.
There were elements of premeditation - Turipa was out for a fight and caused a wound that could have been fatal, said Mr Lucas.
Turipa's lawyer Alistair Clarke said his client recalled little of the incident but accepted the attack was unprovoked.
- Gisborne Herald
