解析包含复杂结构的字符串

Question

I'm receiving a third-party API payload response like:

{
    "message": "Validation failed because [{reason=CONDITIONAL_INVALID_VALUE, field=/targetingCriteria, batchIndex=0, type=INVALID_VALUE, message=/locale cannot be set to en if urn:li:adTargetingFacet:interfaceLocales is set to urn:li:locale:it_IT, parameters={field1=/locale, value2=urn:li:locale:it_IT, value1=en, field2=urn:li:adTargetingFacet:interfaceLocales, key=}}, {reason=FIELD_VALUE_TOO_LOW, field=dailyBudget, batchIndex=0, type=INVALID_VALUE, message=/dailyBudget/amount value 1 cannot be lower than 10.00, parameters={min=10.00, field=/dailyBudget/amount, costType=CPM, type=SPONSORED_UPDATES, value=1, key=}}]",
    "status": 400
}

and I'd like to transform in something like:

{
    "errors": [{
            "reason": "CONDITIONAL_INVALID_VALUE",
            "field": "/targetingCriteria",
            "batchIndex": "0",
            "type": "INVALID_VALUE",
            "message": "/locale cannot be set to en if urn:li:adTargetingFacet:interfaceLocales is set to urn:li:locale:it_IT",
            "parameters": "{field1=/locale, value2=urn:li:locale:it_IT, value1=en, field2=urn:li:adTargetingFacet:interfaceLocales, key=}"
        },
        {
            "reason": "FIELD_VALUE_TOO_LOW",
            "field": "dailyBudget",
            "batchIndex": "0",
            "type": "INVALID_VALUE",
            "message": "/dailyBudget/amount value 1 cannot be lower than 10.00",
            "parameters": "{min=10.00, field=/dailyBudget/amount, costType=CPM, type=SPONSORED_UPDATES, value=1, key=}"
        }
    ]
}

But I'm struggling to find a clear golang approach to this problem, the main problems are:

1. no valid json is available: word are not correctly quoted with "
2. = symbol instead of :
3. nested graphs bracket

I'm currently try to transform in a valid json string and then parse as json but I have various problem with nested elements

Any idea?

EDIT: This is what I've done right now: https://play.golang.org/p/B7bdPCJoHc2