Regarding informal layoff or coercive resignation.

Dear Sir, I am working in an IT company as an engineer from last 8 years. I was on Leave of Absence due to health issue for a period of 3 months & 22 days without pay. And then I was on bench (due to lack of billable project work) as my organization could not allocate me a project matching my skills. Inspite of re-skilling myself and being resourceful, my manager asked me today to resign on the grounds that my previous performance was not good. Back of my previous projects: 2016-17: I was sent to South Africa IBM on deputation for more than 1 year, with a job description matching my skills and after going there the job given to me is an un-related skill. Due to which, I had raised a concern and came back to India after 6 months. This is not reflected in my annual performance appraisal. Then after coming back to India, as I was not assigned a project for 3 months, they initiated PIP(with reason as billability, which is not in my control. 2017-18: I got transferred to a new account in Hyd, from Bangalore. Initial Performance Assessment was positive. But, unfortunately I had severe cough for more than 3 weeks in Jan and in March, and asked my manager for Leave of Absence without pay to manage my health. And told him that this will my impact performance, to which he didn't approve the leave within reasonable time, and approved leave from July 1st week. (with reason as lack of backup for me to do my job) But the appraisal system didn't record these facts, and showing my poor performance as reason, for not giving me a project and asked me to resign. Request you to advise, if I have a legal case against my employer.