"""
This is a direct translation of nvvm.h
"""
from __future__ import print_function, absolute_import, division
import sys, logging, re
from ctypes import (c_void_p, c_int, POINTER, c_char_p, c_size_t, byref,
                    c_char)

import threading

from llvmlite import ir

from numba import config
from .error import NvvmError, NvvmSupportError
from .libs import get_libdevice, open_libdevice, open_cudalib


logger = logging.getLogger(__name__)

ADDRSPACE_GENERIC = 0
ADDRSPACE_GLOBAL = 1
ADDRSPACE_SHARED = 3
ADDRSPACE_CONSTANT = 4
ADDRSPACE_LOCAL = 5

# Opaque handle for compilation unit
nvvm_program = c_void_p

# Result code
nvvm_result = c_int

RESULT_CODE_NAMES = '''
NVVM_SUCCESS
NVVM_ERROR_OUT_OF_MEMORY
NVVM_ERROR_PROGRAM_CREATION_FAILURE
NVVM_ERROR_IR_VERSION_MISMATCH
NVVM_ERROR_INVALID_INPUT
NVVM_ERROR_INVALID_PROGRAM
NVVM_ERROR_INVALID_IR
NVVM_ERROR_INVALID_OPTION
NVVM_ERROR_NO_MODULE_IN_PROGRAM
NVVM_ERROR_COMPILATION
'''.split()

for i, k in enumerate(RESULT_CODE_NAMES):
    setattr(sys.modules[__name__], k, i)


def is_available():
    """
    Return if libNVVM is available
    """
    try:
        NVVM()
    except NvvmSupportError:
        return False
    else:
        return True


_nvvm_lock = threading.Lock()

class NVVM(object):
    '''Process-wide singleton.
    '''
    _PROTOTYPES = {

        # nvvmResult nvvmVersion(int *major, int *minor)
        'nvvmVersion': (nvvm_result, POINTER(c_int), POINTER(c_int)),

        # nvvmResult nvvmCreateProgram(nvvmProgram *cu)
        'nvvmCreateProgram': (nvvm_result, POINTER(nvvm_program)),

        # nvvmResult nvvmDestroyProgram(nvvmProgram *cu)
        'nvvmDestroyProgram': (nvvm_result, POINTER(nvvm_program)),

        # nvvmResult nvvmAddModuleToProgram(nvvmProgram cu, const char *buffer,
        #                                   size_t size, const char *name)
        'nvvmAddModuleToProgram': (
            nvvm_result, nvvm_program, c_char_p, c_size_t, c_char_p),

        # nvvmResult nvvmCompileProgram(nvvmProgram cu, int numOptions,
        #                          const char **options)
        'nvvmCompileProgram': (
            nvvm_result, nvvm_program, c_int, POINTER(c_char_p)),

        # nvvmResult nvvmGetCompiledResultSize(nvvmProgram cu,
        #                                      size_t *bufferSizeRet)
        'nvvmGetCompiledResultSize': (
            nvvm_result, nvvm_program, POINTER(c_size_t)),

        # nvvmResult nvvmGetCompiledResult(nvvmProgram cu, char *buffer)
        'nvvmGetCompiledResult': (nvvm_result, nvvm_program, c_char_p),

        # nvvmResult nvvmGetProgramLogSize(nvvmProgram cu,
        #                                      size_t *bufferSizeRet)
        'nvvmGetProgramLogSize': (nvvm_result, nvvm_program, POINTER(c_size_t)),

        # nvvmResult nvvmGetProgramLog(nvvmProgram cu, char *buffer)
        'nvvmGetProgramLog': (nvvm_result, nvvm_program, c_char_p),
    }

    # Singleton reference
    __INSTANCE = None

    def __new__(cls):
        with _nvvm_lock:
            if cls.__INSTANCE is None:
                cls.__INSTANCE = inst = object.__new__(cls)
                try:
                    inst.driver = open_cudalib('nvvm')
                except OSError as e:
                    cls.__INSTANCE = None
                    errmsg = ("libNVVM cannot be found. Do `conda install "
                              "cudatoolkit`:\n%s")
                    raise NvvmSupportError(errmsg % e)

                # Find & populate functions
                for name, proto in inst._PROTOTYPES.items():
                    func = getattr(inst.driver, name)
                    func.restype = proto[0]
                    func.argtypes = proto[1:]
                    setattr(inst, name, func)

        return cls.__INSTANCE

    def get_version(self):
        major = c_int()
        minor = c_int()
        err = self.nvvmVersion(byref(major), byref(minor))
        self.check_error(err, 'Failed to get version.')
        return major.value, minor.value

    def check_error(self, error, msg, exit=False):
        if error:
            exc = NvvmError(msg, RESULT_CODE_NAMES[error])
            if exit:
                print(exc)
                sys.exit(1)
            else:
                raise exc


class CompilationUnit(object):
    def __init__(self):
        self.driver = NVVM()
        self._handle = nvvm_program()
        err = self.driver.nvvmCreateProgram(byref(self._handle))
        self.driver.check_error(err, 'Failed to create CU')

    def __del__(self):
        driver = NVVM()
        err = driver.nvvmDestroyProgram(byref(self._handle))
        driver.check_error(err, 'Failed to destroy CU', exit=True)

    def add_module(self, buffer):
        """
         Add a module level NVVM IR to a compilation unit.
         - The buffer should contain an NVVM module IR either in the bitcode
           representation (LLVM3.0) or in the text representation.
        """
        err = self.driver.nvvmAddModuleToProgram(self._handle, buffer,
                                                 len(buffer), None)
        self.driver.check_error(err, 'Failed to add module')

    def compile(self, **options):
        """Perform Compilation

        The valid compiler options are

         *   - -g (enable generation of debugging information)
         *   - -opt=
         *     - 0 (disable optimizations)
         *     - 3 (default, enable optimizations)
         *   - -arch=
         *     - compute_20 (default)
         *     - compute_30
         *     - compute_35
         *   - -ftz=
         *     - 0 (default, preserve denormal values, when performing
         *          single-precision floating-point operations)
         *     - 1 (flush denormal values to zero, when performing
         *          single-precision floating-point operations)
         *   - -prec-sqrt=
         *     - 0 (use a faster approximation for single-precision
         *          floating-point square root)
         *     - 1 (default, use IEEE round-to-nearest mode for
         *          single-precision floating-point square root)
         *   - -prec-div=
         *     - 0 (use a faster approximation for single-precision
         *          floating-point division and reciprocals)
         *     - 1 (default, use IEEE round-to-nearest mode for
         *          single-precision floating-point division and reciprocals)
         *   - -fma=
         *     - 0 (disable FMA contraction)
         *     - 1 (default, enable FMA contraction)
         *
         """

        # stringify options
        opts = []
        if 'debug' in options:
            if options.pop('debug'):
                opts.append('-g')

        if options.get('opt'):
            opts.append('-opt=%d' % options.pop('opt'))

        if options.get('arch'):
            opts.append('-arch=%s' % options.pop('arch'))

        other_options = (
            'ftz',
            'prec_sqrt',
            'prec_div',
            'fma',
        )

        for k in other_options:
            if k in options:
                v = int(bool(options.pop(k)))
                opts.append('-%s=%d' % (k.replace('_', '-'), v))

        # If there are any option left
        if options:
            optstr = ', '.join(map(repr, options.keys()))
            raise NvvmError("unsupported option {0}".format(optstr))

        # compile
        c_opts = (c_char_p * len(opts))(*[c_char_p(x.encode('utf8'))
                                          for x in opts])
        err = self.driver.nvvmCompileProgram(self._handle, len(opts), c_opts)
        self._try_error(err, 'Failed to compile\n')

        # get result
        reslen = c_size_t()
        err = self.driver.nvvmGetCompiledResultSize(self._handle, byref(reslen))

        self._try_error(err, 'Failed to get size of compiled result.')

        ptxbuf = (c_char * reslen.value)()
        err = self.driver.nvvmGetCompiledResult(self._handle, ptxbuf)
        self._try_error(err, 'Failed to get compiled result.')

        # get log
        self.log = self.get_log()

        return ptxbuf[:]

    def _try_error(self, err, msg):
        self.driver.check_error(err, "%s\n%s" % (msg, self.get_log()))

    def get_log(self):
        reslen = c_size_t()
        err = self.driver.nvvmGetProgramLogSize(self._handle, byref(reslen))
        self.driver.check_error(err, 'Failed to get compilation log size.')

        if reslen.value > 1:
            logbuf = (c_char * reslen.value)()
            err = self.driver.nvvmGetProgramLog(self._handle, logbuf)
            self.driver.check_error(err, 'Failed to get compilation log.')

            return logbuf.value.decode('utf8')  # populate log attribute

        return ''


data_layout = {
    32: ('e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-'
         'f64:64:64-v16:16:16-v32:32:32-v64:64:64-v128:128:128-n16:32:64'),
    64: ('e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-'
         'f64:64:64-v16:16:16-v32:32:32-v64:64:64-v128:128:128-n16:32:64')}

default_data_layout = data_layout[tuple.__itemsize__ * 8]


try:
    NVVM_VERSION = NVVM().get_version()
except:
    # the CUDA driver may not be present
    NVVM_VERSION = (0, 0)

# List of supported compute capability in sorted order
if NVVM_VERSION < (1, 4):
    # CUDA 8.0
    SUPPORTED_CC = (2, 0), (2, 1), (3, 0), (3, 5), (5, 0), (5, 2), (5, 3), (6, 0), (6, 1), (6, 2)
else:
    # CUDA 9.0 and later
    SUPPORTED_CC = (3, 0), (3, 5), (5, 0), (5, 2), (5, 3), (6, 0), (6, 1), (6, 2), (7, 0)


def _find_arch(mycc):
    for i, cc in enumerate(SUPPORTED_CC):
        if cc == mycc:
            # Matches
            return cc
        elif cc > mycc:
            # Exceeded
            if i == 0:
                # CC lower than supported
                raise NvvmSupportError("GPU compute capability %d.%d is "
                                       "not supported (requires >=%d.%d)" % (mycc + cc))
            else:
                # return the previous CC
                return SUPPORTED_CC[i - 1]

    # CC higher than supported
    return SUPPORTED_CC[-1]  # Choose the highest


def get_arch_option(major, minor):
    """Matches with the closest architecture option
    """
    if config.FORCE_CUDA_CC:
        arch = config.FORCE_CUDA_CC
    else:
        arch = _find_arch((major, minor))
    return 'compute_%d%d' % arch


MISSING_LIBDEVICE_FILE_MSG = '''Missing libdevice file for {arch}.
Please ensure you have package cudatoolkit >= 8.
Install package by:

    conda install cudatoolkit
'''


class LibDevice(object):
    _cache_ = {}
    _known_arch = [
        "compute_20",
        "compute_30",
        "compute_35",
        "compute_50",
    ]

    def __init__(self, arch):
        """
        arch --- must be result from get_arch_option()
        """
        if arch not in self._cache_:
            arch = self._get_closest_arch(arch)
            if get_libdevice(arch) is None:
                raise RuntimeError(MISSING_LIBDEVICE_FILE_MSG.format(arch=arch))
            self._cache_[arch] = open_libdevice(arch)

        self.arch = arch
        self.bc = self._cache_[arch]

    def _get_closest_arch(self, arch):
        res = self._known_arch[0]
        for potential in self._known_arch:
            if arch >= potential:
                res = potential
        return res

    def get(self):
        return self.bc


ir_numba_cas_hack = """
define internal i32 @___numba_cas_hack(i32* %ptr, i32 %cmp, i32 %val) alwaysinline {
    %out = cmpxchg volatile i32* %ptr, i32 %cmp, i32 %val monotonic
    ret i32 %out
}
"""

# Translation of code from CUDA Programming Guide v6.5, section B.12
ir_numba_atomic_double_add = """
define internal double @___numba_atomic_double_add(double* %ptr, double %val) alwaysinline {
entry:
    %iptr = bitcast double* %ptr to i64*
    %old2 = load volatile i64, i64* %iptr
    br label %attempt

attempt:
    %old = phi i64 [ %old2, %entry ], [ %cas, %attempt ]
    %dold = bitcast i64 %old to double
    %dnew = fadd double %dold, %val
    %new = bitcast double %dnew to i64
    %cas = cmpxchg volatile i64* %iptr, i64 %old, i64 %new monotonic
    %repeat = icmp ne i64 %cas, %old
    br i1 %repeat, label %attempt, label %done

done:
    %result = bitcast i64 %old to double
    ret double %result
}
"""

ir_numba_atomic_max = """
define internal {T} @___numba_atomic_{T}_max({T}* %ptr, {T} %val) alwaysinline {{
entry:
    %ptrval = load volatile {T}, {T}* %ptr
    ; Check if val is a NaN and return *ptr early if so
    %valnan = fcmp uno {T} %val, %val
    br i1 %valnan, label %done, label %lt_check

lt_check:
    %dold = phi {T} [ %ptrval, %entry ], [ %dcas, %attempt ]
    ; Continue attempts if dold < val or dold is NaN (using ult semantics)
    %lt = fcmp ult {T} %dold, %val
    br i1 %lt, label %attempt, label %done

attempt:
    ; Attempt to swap in the larger value
    %iold = bitcast {T} %dold to {Ti}
    %iptr = bitcast {T}* %ptr to {Ti}*
    %ival = bitcast {T} %val to {Ti}
    %cas = cmpxchg volatile {Ti}* %iptr, {Ti} %iold, {Ti} %ival monotonic
    %dcas = bitcast {Ti} %cas to {T}
    br label %lt_check

done:
    ; Return max
    %ret = phi {T} [ %ptrval, %entry ], [ %dold, %lt_check ]
    ret {T} %ret
}}
"""


ir_numba_atomic_min = """
define internal {T} @___numba_atomic_{T}_min({T}* %ptr, {T} %val) alwaysinline{{
entry:
    %ptrval = load volatile {T}, {T}* %ptr
    ; Check if val is a NaN and return *ptr early if so
    %valnan = fcmp uno {T} %val, %val
    br i1 %valnan, label %done, label %gt_check

gt_check:
    %dold = phi {T} [ %ptrval, %entry ], [ %dcas, %attempt ]
    ; Continue attempts if dold > val or dold is NaN (using ugt semantics)
    %lt = fcmp ugt {T} %dold, %val
    br i1 %lt, label %attempt, label %done

attempt:
    ; Attempt to swap in the smaller value
    %iold = bitcast {T} %dold to {Ti}
    %iptr = bitcast {T}* %ptr to {Ti}*
    %ival = bitcast {T} %val to {Ti}
    %cas = cmpxchg volatile {Ti}* %iptr, {Ti} %iold, {Ti} %ival monotonic
    %dcas = bitcast {Ti} %cas to {T}
    br label %gt_check

done:
    ; Return min
    %ret = phi {T} [ %ptrval, %entry ], [ %dold, %gt_check ]
    ret {T} %ret
}}
"""


def _replace_datalayout(llvmir):
    """
    Find the line containing the datalayout and replace it
    """
    lines = llvmir.splitlines()
    for i, ln in enumerate(lines):
        if ln.startswith("target datalayout"):
            tmp = 'target datalayout = "{0}"'
            lines[i] = tmp.format(default_data_layout)
            break
    return '\n'.join(lines)


def llvm_to_ptx(llvmir, **opts):
    cu = CompilationUnit()
    libdevice = LibDevice(arch=opts.get('arch', 'compute_20'))
    # New LLVM generate a shorthand for datalayout that NVVM does not know
    llvmir = _replace_datalayout(llvmir)
    # Replace with our cmpxchg and atomic implementations because LLVM 3.5 has
    # a new semantic for cmpxchg.
    replacements = [
        ('declare i32 @___numba_cas_hack(i32*, i32, i32)',
         ir_numba_cas_hack),
        ('declare double @___numba_atomic_double_add(double*, double)',
         ir_numba_atomic_double_add),
        ('declare float @___numba_atomic_float_max(float*, float)',
         ir_numba_atomic_max.format(T='float', Ti='i32')),
        ('declare double @___numba_atomic_double_max(double*, double)',
         ir_numba_atomic_max.format(T='double', Ti='i64')),
        ('declare float @___numba_atomic_float_min(float*, float)',
         ir_numba_atomic_min.format(T='float', Ti='i32')),
        ('declare double @___numba_atomic_double_min(double*, double)',
         ir_numba_atomic_min.format(T='double', Ti='i64')),
    ]

    for decl, fn in replacements:
        llvmir = llvmir.replace(decl, fn)

    llvmir = llvm39_to_34_ir(llvmir)
    cu.add_module(llvmir.encode('utf8'))
    cu.add_module(libdevice.get())

    ptx = cu.compile(**opts)
    # XXX remove debug_pubnames seems to be necessary sometimes
    return patch_ptx_debug_pubnames(ptx)


def patch_ptx_debug_pubnames(ptx):
    """
    Patch PTX to workaround .debug_pubnames NVVM error::

        ptxas fatal   : Internal error: overlapping non-identical data

    """
    while True:
        # Repeatedly remove debug_pubnames sections
        start = ptx.find(b'.section .debug_pubnames')
        if start < 0:
            break
        stop = ptx.find(b'}', start)
        if stop < 0:
            raise ValueError('missing "}"')
        ptx = ptx[:start] + ptx[stop + 1:]
    return ptx


re_metadata_def = re.compile(r"\!\d+\s*=")
re_metadata_correct_usage = re.compile(r"metadata\s*\![{'\"0-9]")
re_metadata_ref = re.compile(r"\!\d+")
re_metadata_debuginfo = re.compile(r"\!{i32 \d, \!\"Debug Info Version\", i32 \d}".replace(' ', r'\s+'))

re_attributes_def = re.compile(r"^attributes #\d+ = \{ ([\w\s]+)\ }")
supported_attributes = {'alwaysinline', 'cold', 'inlinehint', 'minsize',
                        'noduplicate', 'noinline', 'noreturn', 'nounwind',
                        'optnone', 'optisze', 'readnone', 'readonly'}

re_getelementptr = re.compile(r"\bgetelementptr\s(?:inbounds )?\(?")

re_load = re.compile(r"=\s*\bload\s(?:\bvolatile\s)?")

re_call = re.compile(r"(call\s[^@]+\))(\s@)")
re_range = re.compile(r"\s*!range\s+!\d+")

re_type_tok = re.compile(r"[,{}()[\]]")

re_annotations = re.compile(r"\bnonnull\b")

re_unsupported_keywords = re.compile(r"\b(local_unnamed_addr|writeonly)\b")

re_parenthesized_list = re.compile(r"\((.*)\)")


def llvm39_to_34_ir(ir):
    """
    Convert LLVM 3.9 IR for LLVM 3.4.
    """
    def parse_out_leading_type(s):
        par_level = 0
        pos = 0
        # Parse out the first <ty> (which may be an aggregate type)
        while True:
            m = re_type_tok.search(s, pos)
            if m is None:
                # End of line
                raise RuntimeError("failed parsing leading type: %s" % (s,))
                break
            pos = m.end()
            tok = m.group(0)
            if tok == ',':
                if par_level == 0:
                    # End of operand
                    break
            elif tok in '{[(':
                par_level += 1
            elif tok in ')]}':
                par_level -= 1
        return s[pos:].lstrip()

    buf = []
    for line in ir.splitlines():

        # Fix llvm.dbg.cu
        if line.startswith('!numba.llvm.dbg.cu'):
            line = line.replace('!numba.llvm.dbg.cu', '!llvm.dbg.cu')

        # We insert a dummy inlineasm to put debuginfo
        if (line.lstrip().startswith('tail call void asm sideeffect "// dbg') and
                '!numba.dbg' in line):
            # Fix the metadata
            line = line.replace('!numba.dbg', '!dbg')
        if re_metadata_def.match(line):
            # Rewrite metadata since LLVM 3.7 dropped the "metadata" type prefix.
            if None is re_metadata_correct_usage.search(line):
                # Reintroduce the "metadata" prefix
                line = line.replace('!{', 'metadata !{')
                line = line.replace('!"', 'metadata !"')

                assigpos = line.find('=')
                lhs, rhs = line[:assigpos + 1], line[assigpos + 1:]

                # Fix metadata reference
                def fix_metadata_ref(m):
                    return 'metadata ' + m.group(0)
                line = ' '.join((lhs, re_metadata_ref.sub(fix_metadata_ref, rhs)))
        if line.startswith('source_filename ='):
            continue    # skip line
        if re_unsupported_keywords.search(line) is not None:
            line = re_unsupported_keywords.sub(lambda m: '', line)

        if line.startswith('attributes #'):
            # Remove function attributes unsupported pre-3.8
            m = re_attributes_def.match(line)
            attrs = m.group(1).split()
            attrs = ' '.join(a for a in attrs if a in supported_attributes)
            line = line.replace(m.group(1), attrs)
        if 'getelementptr ' in line:
            # Rewrite "getelementptr ty, ty* ptr, ..."
            # to "getelementptr ty *ptr, ..."
            m = re_getelementptr.search(line)
            if m is None:
                raise RuntimeError("failed parsing getelementptr: %s" % (line,))
            pos = m.end()
            line = line[:pos] + parse_out_leading_type(line[pos:])
        if 'load ' in line:
            # Rewrite "load ty, ty* ptr"
            # to "load ty *ptr"
            m = re_load.search(line)
            if m:
                pos = m.end()
                line = line[:pos] + parse_out_leading_type(line[pos:])
        if 'call ' in line:
            # Rewrite "call ty (...) @foo"
            # to "call ty (...)* @foo"
            line = re_call.sub(r"\1*\2", line)

            # no !range metadata on calls
            line = re_range.sub('', line).rstrip(',')

            if '@llvm.memset' in line:
                line = re_parenthesized_list.sub(
                    _replace_llvm_memset_usage,
                    line,
                    )
        if 'declare' in line:
            if '@llvm.memset' in line:
                line = re_parenthesized_list.sub(
                    _replace_llvm_memset_declaration,
                    line,
                    )

        # Remove unknown annotations
        line = re_annotations.sub('', line)

        buf.append(line)

    return '\n'.join(buf)


def _replace_llvm_memset_usage(m):
    """Replace `llvm.memset` usage for llvm7+.

    Used as functor for `re.sub.
    """
    params = list(m.group(1).split(','))
    align = re.search(r'align (\d+)', params[0]).group(1)
    params.insert(-1, 'i32 {}'.format(align))
    out = ', '.join(params)
    return '({})'.format(out)


def _replace_llvm_memset_declaration(m):
    """Replace `llvm.memset` declaration for llvm7+.

    Used as functor for `re.sub.
    """
    params = list(m.group(1).split(','))
    params.insert(-1, 'i32')
    out = ', '.join(params)
    return '({})'.format(out)


def set_cuda_kernel(lfunc):
    from llvmlite.llvmpy.core import MetaData, MetaDataString, Constant, Type

    m = lfunc.module

    ops = lfunc, MetaDataString.get(m, "kernel"), Constant.int(Type.int(), 1)
    md = MetaData.get(m, ops)

    nmd = m.get_or_insert_named_metadata('nvvm.annotations')
    nmd.add(md)

    # set nvvm ir version
    i32 = ir.IntType(32)
    md_ver = m.add_metadata([i32(1), i32(2), i32(2), i32(0)])
    m.add_named_metadata('nvvmir.version', md_ver)


def fix_data_layout(module):
    module.data_layout = default_data_layout
