import pytest
import torch
from celestis_rl import selected_linear_scores, draw_correction, token_loss, selected_token_loss


@pytest.mark.parametrize("chunk",[1,3,17,30])
@pytest.mark.parametrize("temperature",[.7,1.,2.])
def test_selected_backward_matches_dense(chunk,temperature):
    torch.manual_seed(4)
    h=torch.randn(4,6,dtype=torch.float64,requires_grad=True)
    w=torch.randn(17,6,dtype=torch.float64,requires_grad=True)
    bias=torch.randn(17,dtype=torch.float64,requires_grad=True)
    q=(torch.randn(2,2,17,dtype=torch.float64)*2).softmax(-1)
    mask=torch.ones(2,2,dtype=torch.bool)
    actions=torch.tensor([[1,7],[8,9]])
    corr=draw_correction(q,mask,5,generator=torch.Generator().manual_seed(8))
    ids=torch.cat([actions[...,None],corr.ids],-1).reshape(4,-1)
    scores=selected_linear_scores(h,w,ids,bias=bias,chunk_size=chunk,temperature=temperature)
    logits=scores.logits.reshape(2,2,-1); lp=scores.log_probs.reshape(2,2,-1)
    qlog=q.gather(-1,actions[...,None]).squeeze(-1).log()
    reward=torch.tensor([1.,.2],dtype=torch.float64)
    loss,_=selected_token_loss(logits[...,0],logits[...,1:],corr,lp[...,0],qlog,reward)
    gs=torch.autograd.grad(loss,(h,w,bias))
    dense=((h@w.T+bias)/temperature).reshape(2,2,-1)
    dl,_=token_loss(dense,actions,q,mask,reward,correction=corr)
    gd=torch.autograd.grad(dl,(h,w,bias))
    assert torch.allclose(scores.log_probs, dense.detach().reshape(4,17).log_softmax(-1).gather(-1,ids),atol=1e-13,rtol=1e-13)
    for a,b in zip(gs,gd):
        assert torch.allclose(a,b,atol=2e-13,rtol=2e-13)


def test_tied_input_output_embedding_gradient():
    torch.manual_seed(23)
    w=torch.randn(11,4,dtype=torch.float64,requires_grad=True)
    input_ids=torch.tensor([2,6]); a=torch.tensor([[1],[4]])
    q=torch.randn(2,1,11,dtype=torch.float64).softmax(-1)
    m=torch.ones(2,1,dtype=torch.bool)
    rec=draw_correction(q,m,3,generator=torch.Generator().manual_seed(9))
    ids=torch.cat((a[...,None],rec.ids),-1).reshape(2,-1)
    reward=torch.tensor([1.,-.1],dtype=torch.float64)
    h=w[input_ids]*.4
    scores=selected_linear_scores(h,w,ids,chunk_size=3)
    z=scores.logits[:,None]; lp=scores.log_probs[:,None]
    qlog=q.gather(-1,a[...,None]).squeeze(-1).log()
    l,_=selected_token_loss(z[...,0],z[...,1:],rec,lp[...,0],qlog,reward)
    g1=torch.autograd.grad(l,w)[0]
    dense=(w[input_ids]*.4@w.T)[:,None]
    l2,_=token_loss(dense,a,q,m,reward,correction=rec)
    g2=torch.autograd.grad(l2,w)[0]
    assert torch.allclose(g1,g2,atol=1e-13)


def test_extreme_scores_and_float32_precision():
    h=torch.tensor([[100.,-100.]],requires_grad=True)
    w=torch.tensor([[100.,100.],[-100.,100.],[100.,-100.]],requires_grad=True)
    s=selected_linear_scores(h,w,torch.tensor([[0,2]]),chunk_size=1)
    assert torch.isfinite(s.log_probs).all()
    assert s.log_probs[0,1] == 0
    assert not s.log_probs.requires_grad


@pytest.mark.parametrize("bad", [0,-1,1.5])
def test_bad_chunk_size(bad):
    with pytest.raises(ValueError):
        selected_linear_scores(torch.ones(1,2),torch.ones(3,2),torch.tensor([[1]]),chunk_size=bad)