import pytest
import torch
from torch.testing import assert_close

import triton
import triton.language as tl


@triton.jit
def matmul_no_scf_kernel(
    a_ptr, b_ptr, c_ptr,
    stride_am, stride_ak,
    stride_bk, stride_bn,
    stride_cm, stride_cn,
    M: tl.constexpr, N: tl.constexpr, K: tl.constexpr
):
    offs_m = tl.arange(0, M)
    offs_n = tl.arange(0, N)
    offs_k = tl.arange(0, K)
    a_ptrs = a_ptr + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
    b_ptrs = b_ptr + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
    a = tl.load(a_ptrs)
    b = tl.load(b_ptrs)

    c = tl.dot(a, b)

    c_ptrs = c_ptr + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
    tl.store(c_ptrs, c)

# TODO: num_warps could only be 4 for now


@pytest.mark.parametrize('SIZE_M,SIZE_N,SIZE_K,NUM_WARPS', [
    [128, 256, 32, 4],
    [256, 128, 16, 4],
    [128, 16, 32, 4],
    [32, 128, 64, 4],
    [128, 128, 64, 4],
    [64, 128, 128, 4],
    [64, 128, 128, 2],
])
def test_gemm_no_scf(SIZE_M, SIZE_N, SIZE_K, NUM_WARPS):
    a = torch.randn((SIZE_M, SIZE_K), device='cuda', dtype=torch.float16)
    b = torch.randn((SIZE_K, SIZE_N), device='cuda', dtype=torch.float16)
    c = torch.empty((SIZE_M, SIZE_N), device=a.device, dtype=torch.float32)
    grid = lambda META: (1, )
    matmul_no_scf_kernel[grid](a_ptr=a, b_ptr=b, c_ptr=c,
                               stride_am=a.stride(0), stride_ak=a.stride(1),
                               stride_bk=b.stride(0), stride_bn=b.stride(1),
                               stride_cm=c.stride(0), stride_cn=c.stride(1),
                               M=SIZE_M, N=SIZE_N, K=SIZE_K,
                               num_warps=NUM_WARPS)
    golden = torch.matmul(a, b)
    torch.set_printoptions(profile="full")
    assert_close(c, golden, rtol=1e-3, atol=1e-3, check_dtype=False)


@triton.jit
def matmul_kernel(
    a_ptr, b_ptr, c_ptr,
    stride_am, stride_ak,
    stride_bk, stride_bn,
    stride_cm, stride_cn,
    M: tl.constexpr, N: tl.constexpr, K: tl.constexpr,
    BLOCK_SIZE_M: tl.constexpr, BLOCK_SIZE_N: tl.constexpr, BLOCK_SIZE_K: tl.constexpr,
):
    offs_m = tl.arange(0, BLOCK_SIZE_M)
    offs_n = tl.arange(0, BLOCK_SIZE_N)
    offs_k = tl.arange(0, BLOCK_SIZE_K)
    a_ptrs = a_ptr + offs_m[:, None] * stride_am + offs_k[None, :] * stride_ak
    b_ptrs = b_ptr + offs_k[:, None] * stride_bk + offs_n[None, :] * stride_bn
    accumulator = tl.zeros((BLOCK_SIZE_M, BLOCK_SIZE_N), dtype=tl.float32)
    for k in range(0, K, BLOCK_SIZE_K):
        a = tl.load(a_ptrs)
        b = tl.load(b_ptrs)
        accumulator += tl.dot(a, b)
        a_ptrs += BLOCK_SIZE_K * stride_ak
        b_ptrs += BLOCK_SIZE_K * stride_bk

    c_ptrs = c_ptr + offs_m[:, None] * stride_cm + offs_n[None, :] * stride_cn
    tl.store(c_ptrs, accumulator)

# TODO: DotConversion in TritonGPUToLLVM cannot support non-splat C for the moment


def get_variant_golden(a, b):
    SIZE_M = a.shape[0]
    SIZE_K = a.shape[1]
    SIZE_N = b.shape[1]
    assert a.shape[1] == b.shape[0]
    zero_M_K = torch.zeros((SIZE_M, SIZE_K)).cuda()
    zero_3M_K = torch.zeros((3 * SIZE_M, SIZE_K)).cuda()
    zero_K_N = torch.zeros((SIZE_K, SIZE_N)).cuda()
    zero_3K_N = torch.zeros((3 * SIZE_K, SIZE_N)).cuda()
    a_padded = torch.cat((a, zero_M_K, zero_M_K), 0)
    a_padded = torch.cat((a_padded, zero_3M_K, zero_3M_K), 1)
    b_padded = torch.cat((b, zero_K_N, zero_K_N), 0)
    b_padded = torch.cat((b_padded, zero_3K_N, zero_3K_N), 1)
    c_padded = torch.matmul(a_padded, b_padded)
    return c_padded[:SIZE_M, :SIZE_N]


@pytest.mark.parametrize('SIZE_M,SIZE_N,SIZE_K,NUM_WARPS,BLOCK_SIZE_M,BLOCK_SIZE_N,BLOCK_SIZE_K', [
    # Non-forloop
    [64, 32, 64, 4, 64, 32, 64],
    [128, 64, 128, 4, 128, 64, 128],
    # K-Forloop
    [64, 32, 128, 4, 64, 32, 64],
    [128, 16, 128, 4, 128, 16, 32],
    [32, 16, 128, 4, 32, 16, 32],
    [32, 64, 128, 4, 32, 64, 32],
    [32, 128, 256, 4, 32, 128, 64],
    [64, 128, 64, 4, 64, 128, 32],
    [64, 64, 128, 4, 64, 64, 32],
    [128, 128, 64, 4, 128, 128, 32],
    [128, 128, 128, 4, 128, 128, 32],
    [128, 128, 256, 4, 128, 128, 64],
    [128, 256, 128, 4, 128, 256, 32],
    [256, 128, 64, 4, 256, 128, 16],
    [128, 64, 128, 4, 128, 64, 32],
])
def test_gemm(SIZE_M, SIZE_N, SIZE_K, NUM_WARPS, BLOCK_SIZE_M, BLOCK_SIZE_N, BLOCK_SIZE_K):
    a = torch.randn((SIZE_M, SIZE_K), device='cuda', dtype=torch.float16)
    b = torch.randn((SIZE_K, SIZE_N), device='cuda', dtype=torch.float16)
    c = torch.empty((SIZE_M, SIZE_N), device=a.device, dtype=torch.float32)
    grid = lambda META: (1, )
    matmul_kernel[grid](a_ptr=a, b_ptr=b, c_ptr=c,
                        stride_am=a.stride(0), stride_ak=a.stride(1),
                        stride_bk=b.stride(0), stride_bn=b.stride(1),
                        stride_cm=c.stride(0), stride_cn=c.stride(1),
                        M=a.shape[0], N=b.shape[1], K=a.shape[1],
                        BLOCK_SIZE_M=BLOCK_SIZE_M, BLOCK_SIZE_N=BLOCK_SIZE_N, BLOCK_SIZE_K=BLOCK_SIZE_K,
                        num_warps=NUM_WARPS)
    golden = torch.matmul(a, b)

    # It's not easy to get a proper error threshold in different size
    # Here the gemm calculation is padded to a different size in order to get
    # a variant version of the golden result. And the error between golden and
    # golden_variant provide reference on selecting the proper rtol / atol.
    golden_variant = get_variant_golden(a, b)
    golden_diff = golden - golden_variant
    golden_abs_err = torch.max(torch.abs(golden_diff)).item()
    golden_rel_err = torch.max(torch.abs(golden_diff / golden)).item()

    torch.set_printoptions(profile="full")
    assert_close(c, golden, rtol=max(1e-4, 1.5 * golden_rel_err), atol=max(1e-4, 1.5 * golden_abs_err), check_dtype=False)