S. R. Faruqi:

kisī se basar ānā = to obtain control over someone

One meaning of basar ānā is also 'to reach a conclusion/culmination'. If the prose of the first line would be taken like this

mīr tum vaise farebī se kab basar āʾe

then the meaning will be 'Mir, when were you able to obtain control of a tricker like that?' But if the prose would be made so that the second part of the first line ( tum vaise farebī se ) would be read in connection with the second line, then the prose will be like this:

mīr kab basar āʾe? tum vaise farebī se dil ko to lagā baiṭhe, lekin ( us ko ) nah lagā ( huʾā ) jānā

In this case, the interpretation will be, 'Mir, as if you'll ever arrive at a good result (when will your tasks/projects be completed?). You're so naive and simple that you've settled on attaching your heart to a trickster like her, but you still haven't been able to consider/know that your heart has been attached! On both readings, the theme of the second line is very beautiful-- that the heart has been conquered, but the beloved has taken the heart with such a high order of cleverness that Mir still doesn't realize it.

This is an extremely subtle account of one event/'affair' [muʿāmilah] of passion. In the verse he's also versified the rhyme very well, and Mir's mastery of the everyday idiom is conspicuous. One interpretation of lagā jānā is also 'to know the method of attaching'. In this case, the interpretation becomes, 'You fell into passionate love, that is, the heart was conquered, but as yet you didn't know anything about the method of passion-- the Lord knows what will happen to you!'. He's composed a fine verse.

There are other verses of this rhetorical style too-- that is, in which the poet speaks to himself, or some other individual speaks to the poet. Compare verses like

{14,7},

{71,3}.

FWP:

SETS == MIDPOINTS
MOTIFS
NAMES
TERMS == 'AFFAIR-EVOCATION'

Note for grammar fans: lagā baiṭhe should be taken as a compound verb ('insisted on attaching', 'wouldn't rest without attaching'). There's no grammatical reason we couldn't alternatively take it as a case of kar deletion, but 'having attached, sat down' makes no particular sense in the context of the verse. Then, lagā jānā is most readily construed as a perfect participle form, short for lagā huʾā jānā , 'considered [to be] [in a state of having been] attached'. (Remember that jān'nā doesn't imply, as 'to know' usually does in English, accurate knowledge.) The alternative reading proposed by SRF, lagā jānā as 'knew attachment, knew how to attach', apparently treats lagā as a noun. Nowadays it would be us ne lagānā jānā , where lagānā could be taken either as the infinitive or as a noun made from it.