desperate.groovy

def profileInfo(username) {
    final String TOK1 = 'window._sharedData = '
    final String TOK2 = ';</script>'
    def insta = "https://instagram.com/${username}".toURL().text
    def text = insta.split(TOK1)[1].split(TOK2)[0]
    def json = new groovy.json.JsonSlurper().parseText(text)
    [username: username,
     followers: json.entry_data.ProfilePage[0].user.followed_by.count,
     media: json.entry_data.ProfilePage[0].user.media.nodes.collect( { item -> item.subMap(['code', 'date', 'caption', 'likes', 'comments']) } )
    ]
}

def mediaInfo(code) {
    final String TOK1 = 'window._sharedData = '
    final String TOK2 = ';</script>'
    def insta = "https://instagram.com/p/${code}".toURL().text
    def text = insta.split(TOK1)[1].split(TOK2)[0]
    def json = new groovy.json.JsonSlurper().parseText(text)
    def media = json.entry_data.PostPage[0].media
    media.subMap(['code', 'caption', 'display_src', 'comments', 'likes'])
}

def findPost(username, cadena, since=null) {
    def media = profileInfo(username).media
    media.findAll { it-> it.date > since && it.caption?.toUpperCase()?.contains(cadena.toUpperCase()) }
}

println findPost('jorge.uriarte.aretxaga', 'marmita')
println mediaInfo('BOsm0AlAcPL')