import gdb
import re
import sys

# some feedback that the nim runtime support is loading, isn't a bad
# thing at all.
gdb.write("Loading Nim Runtime support.\n", gdb.STDERR)

# When error occure they occur regularly. This 'caches' known errors
# and prevents them from being reprinted over and over again.
errorSet = set()
def printErrorOnce(id, message):
  global errorSet
  if id not in errorSet:
    errorSet.add(id)
    gdb.write(message, gdb.STDERR)


################################################################################
#####  Type pretty printers
################################################################################

type_hash_regex = re.compile("^\w*_([A-Za-z0-9]*)$")

def getNimRti(type_name):
  """ Return a ``gdb.Value`` object for the Nim Runtime Information of ``type_name``. """

  # Get static const TNimType variable. This should be available for
  # every non trivial Nim type.
  m = type_hash_regex.match(type_name)
  if m:
    try:
      return gdb.parse_and_eval("NTI__" + m.group(1) + "_")
    except:
      return None

def getNameFromNimRti(rti_val):
  """ Return name (or None) given a Nim RTI ``gdb.Value`` """
  try:
    # sometimes there isn't a name field -- example enums
    return rti['name'].string(encoding="utf-8", errors="ignore")
  except:
    return None

class NimTypeRecognizer:
  # this type map maps from types that are generated in the C files to
  # how they are called in nim. To not mix up the name ``int`` from
  # system.nim with the name ``int`` that could still appear in
  # generated code, ``NI`` is mapped to ``system.int`` and not just
  # ``int``.

  type_map_static = {
    'NI': 'system.int',  'NI8': 'int8', 'NI16': 'int16',  'NI32': 'int32',
    'NI64': 'int64',
    
    'NU': 'uint', 'NU8': 'uint8','NU16': 'uint16', 'NU32': 'uint32',
    'NU64': 'uint64',
    
    'NF': 'float', 'NF32': 'float32', 'NF64': 'float64',
    
    'NIM_BOOL': 'bool',

    'NIM_CHAR': 'char', 'NCSTRING': 'cstring', 'NimStringDesc': 'string'
  }

  # object_type_pattern = re.compile("^(\w*):ObjectType$")

  def recognize(self, type_obj):
    # skip things we can't handle like functions
    if type_obj.code in [gdb.TYPE_CODE_FUNC, gdb.TYPE_CODE_VOID]:
      return None

    tname = None
    if type_obj.tag is not None:
      tname = type_obj.tag
    elif type_obj.name is not None:
      tname = type_obj.name

    # handle pointer types
    if not tname:
      target_type = type_obj
      if type_obj.code in [gdb.TYPE_CODE_PTR]:
        target_type = type_obj.target()

      if target_type.name:
        # visualize 'string' as non pointer type (unpack pointer type).
        if target_type.name == "NimStringDesc":
          tname = target_type.name # could also just return 'string'
        else:
          rti = getNimRti(target_type.name)
          if rti:
            return getNameFromNimRti(rti)

    if tname:
      result = self.type_map_static.get(tname, None)
      if result:
        return result

      rti = getNimRti(tname)
      if rti:
        return getNameFromNimRti(rti)

    return None

class NimTypePrinter:
  """Nim type printer. One printer for all Nim types."""

  # enabling and disabling of type printers can be done with the
  # following gdb commands:
  #
  #   enable  type-printer NimTypePrinter
  #   disable type-printer NimTypePrinter
  # relevant docs: https://sourceware.org/gdb/onlinedocs/gdb/Type-Printing-API.html

  name = "NimTypePrinter"

  def __init__(self):
    self.enabled = True

  def instantiate(self):
    return NimTypeRecognizer()

################################################################################
#####  GDB Function, equivalent of Nim's $ operator
################################################################################

class DollarPrintFunction (gdb.Function):
  "Nim's equivalent of $ operator as a gdb function, available in expressions `print $dollar(myvalue)"

  dollar_functions = re.findall(
    'NimStringDesc \*(dollar__[A-z0-9_]+?)\(([^,)]*)\);',
    gdb.execute("info functions dollar__", True, True)
  )

  def __init__ (self):
    super (DollarPrintFunction, self).__init__("dollar")


  @staticmethod
  def invoke_static(arg):

    if arg.type.code == gdb.TYPE_CODE_PTR and arg.type.target().name == "NimStringDesc":
      return arg

    argTypeName = str(arg.type)

    for func, arg_typ in DollarPrintFunction.dollar_functions:
      # this way of overload resolution cannot deal with type aliases,
      # therefore it won't find all overloads.
      if arg_typ == argTypeName:
        func_value = gdb.lookup_global_symbol(func, gdb.SYMBOL_FUNCTIONS_DOMAIN).value()
        return func_value(arg)

      elif arg_typ == argTypeName + " *":
        func_value = gdb.lookup_global_symbol(func, gdb.SYMBOL_FUNCTIONS_DOMAIN).value()
        return func_value(arg.address)

    printErrorOnce(argTypeName, "No suitable Nim $ operator found for type: " + argTypeName + "\n")
    return None

  def invoke(self, arg):
    return self.invoke_static(arg)

DollarPrintFunction()


################################################################################
#####  GDB Function, Nim string comparison
################################################################################

class NimStringEqFunction (gdb.Function):
  """Compare Nim strings for example in conditionals for breakpoints."""

  def __init__ (self):
    super (NimStringEqFunction, self).__init__("nimstreq")

  @staticmethod
  def invoke_static(arg1,arg2):
    if arg1.type.code == gdb.TYPE_CODE_PTR and arg1.type.target().name == "NimStringDesc":
      str1 = NimStringPrinter(arg1).to_string()
    else:
      str1 = arg1.string()
    if arg2.type.code == gdb.TYPE_CODE_PTR and arg2.type.target().name == "NimStringDesc":
      str2 = NimStringPrinter(arg1).to_string()
    else:
      str2 = arg2.string()

    return str1 == str2

  def invoke(self, arg1, arg2):
    return self.invoke_static(arg1, arg2)

NimStringEqFunction()

################################################################################
#####  GDB Command, equivalent of Nim's $ operator
################################################################################

class DollarPrintCmd (gdb.Command):
  """Dollar print command for Nim, `$ expr` will invoke Nim's $ operator and print the result."""

  def __init__ (self):
    super (DollarPrintCmd, self).__init__ ("$", gdb.COMMAND_DATA, gdb.COMPLETE_EXPRESSION)

  def invoke(self, arg, from_tty):
    param = gdb.parse_and_eval(arg)
    strValue = DollarPrintFunction.invoke_static(param)
    if strValue:
      gdb.write(
        NimStringPrinter(strValue).to_string() + "\n",
        gdb.STDOUT
      )

    # could not find a suitable dollar overload. This here is the
    # fallback to get sensible output of basic types anyway.

    elif param.type.code == gdb.TYPE_CODE_ARRAY and param.type.target().name == "char":
      gdb.write(param.string("utf-8", "ignore") + "\n", gdb.STDOUT)
    elif param.type.code == gdb.TYPE_CODE_INT:
      gdb.write(str(int(param)) + "\n", gdb.STDOUT)
    elif param.type.name == "NIM_BOOL":
      if int(param) != 0:
        gdb.write("true\n", gdb.STDOUT)
      else:
        gdb.write("false\n", gdb.STDOUT)

DollarPrintCmd()


################################################################################
#####  GDB Commands to invoke common nim tools.
################################################################################


import subprocess, os


class KochCmd (gdb.Command):
  """Command that invokes ``koch'', the build tool for the compiler."""

  def __init__ (self):
    super (KochCmd, self).__init__ ("koch",
                                    gdb.COMMAND_USER, gdb.COMPLETE_FILENAME)
    self.binary = os.path.join(
      os.path.dirname(os.path.dirname(__file__)), "koch")

  def invoke(self, argument, from_tty):
    import os
    subprocess.run([self.binary] + gdb.string_to_argv(argument))

KochCmd()


class NimCmd (gdb.Command):
  """Command that invokes ``nim'', the nim compiler."""

  def __init__ (self):
    super (NimCmd, self).__init__ ("nim",
                                   gdb.COMMAND_USER, gdb.COMPLETE_FILENAME)
    self.binary = os.path.join(
      os.path.dirname(os.path.dirname(__file__)), "bin/nim")

  def invoke(self, argument, from_tty):
    subprocess.run([self.binary] + gdb.string_to_argv(argument))

NimCmd()


class NimbleCmd (gdb.Command):
  """Command that invokes ``nimble'', the nim package manager and build tool."""

  def __init__ (self):
    super (NimbleCmd, self).__init__ ("nimble",
                                      gdb.COMMAND_USER, gdb.COMPLETE_FILENAME)
    self.binary = os.path.join(
      os.path.dirname(os.path.dirname(__file__)), "bin/nimble")

  def invoke(self, argument, from_tty):
    subprocess.run([self.binary] + gdb.string_to_argv(argument))

NimbleCmd()

################################################################################
#####  Value pretty printers
################################################################################

class NimBoolPrinter:

  pattern = re.compile(r'^NIM_BOOL$')

  def __init__(self, val):
    self.val = val

  def to_string(self):
    if self.val == 0:
      return "false"
    else:
      return "true"

################################################################################

class NimStringPrinter:
  pattern = re.compile(r'^NimStringDesc \*$')

  def __init__(self, val):
    self.val = val

  def display_hint(self):
    return 'string'

  def to_string(self):
    if self.val:
      l = int(self.val['Sup']['len'])
      return self.val['data'].lazy_string(encoding="utf-8", length=l)
    else:
      return ""

# class NimStringPrinter:
#   pattern = re.compile(r'^NimStringDesc$')

#   def __init__(self, val):
#     self.val = val
  
#   def display_hint(self):
#     return 'string'
  
#   def to_string(self):
#     if self.val:
#       l = int(self.val['Sup']['len'])
#       return self.val['data'].lazy_string(encoding="utf-8", length=l)
#     else:
#       return ""

class NimRopePrinter:
  pattern = re.compile(r'^tyObject_RopeObj__([A-Za-z0-9]*) \*$')

  def __init__(self, val):
    self.val = val

  def display_hint(self):
    return 'string'

  def to_string(self):
    if self.val:
      left  = NimRopePrinter(self.val["left"]).to_string()
      data  = NimStringPrinter(self.val["data"]).to_string()
      right = NimRopePrinter(self.val["right"]).to_string()
      return left + data + right
    else:
      return ""


################################################################################

# proc reprEnum(e: int, typ: PNimType): string {.compilerRtl.} =
#   ## Return string representation for enumeration values
#   var n = typ.node
#   if ntfEnumHole notin typ.flags:
#     let o = e - n.sons[0].offset
#     if o >= 0 and o <% typ.node.len:
#       return $n.sons[o].name
#   else:
#     # ugh we need a slow linear search:
#     var s = n.sons
#     for i in 0 .. n.len-1:
#       if s[i].offset == e:
#         return $s[i].name
#   result = $e & " (invalid data!)"

def reprEnum(e, typ):
  """ this is a port of the nim runtime function `reprEnum` to python """
  e = int(e)
  n = typ["node"]
  flags = int(typ["flags"])
  # 1 << 2 is {ntfEnumHole}
  if ((1 << 2) & flags) == 0:
    o = e - int(n["sons"][0]["offset"])
    if o >= 0 and 0 < int(n["len"]):
      return n["sons"][o]["name"].string("utf-8", "ignore")
  else:
    # ugh we need a slow linear search:
    s = n["sons"]
    for i in range(0, int(n["len"])):
      if int(s[i]["offset"]) == e:
        return s[i]["name"].string("utf-8", "ignore")

  return str(e) + " (invalid data!)"

class NimEnumPrinter:
  pattern = re.compile(r'^tyEnum_(\w*)__([A-Za-z0-9]*)$')

  def __init__(self, val):
    self.val = val
    typeName = self.val.type.name
    match = self.pattern.match(typeName)
    self.typeNimName  = match.group(1)
    typeInfoName = "NTI__" + match.group(2) + "_"
    self.nti = gdb.lookup_global_symbol(typeInfoName)

    if self.nti is None:
      printErrorOnce(typeInfoName, f"NimEnumPrinter: lookup global symbol '{typeInfoName}' failed for {typeName}.\n")

  def to_string(self):
    if self.nti:
      arg0     = self.val
      arg1     = self.nti.value(gdb.newest_frame())
      return reprEnum(arg0, arg1)
    else:
      return self.typeNimName + "(" + str(int(self.val)) + ")"

################################################################################

class NimSetPrinter:
  ## the set printer is limited to sets that fit in an integer.  Other
  ## sets are compiled to `NU8 *` (ptr uint8) and are invisible to
  ## gdb (currently).
  pattern = re.compile(r'^tySet_tyEnum_(\w*)_([A-Za-z0-9]*)$')

  def __init__(self, val):
    self.val = val
    match = self.pattern.match(self.val.type.name)
    self.typeNimName  = match.group(1)

    typeInfoName = "NTI__" + match.group(2) + "_"
    self.nti = gdb.lookup_global_symbol(typeInfoName)

    if self.nti is None:
      printErrorOnce(typeInfoName, "NimSetPrinter: lookup global symbol '"+ typeInfoName +" failed for " + self.val.type.name + ".\n")

  def to_string(self):
    if self.nti:
      nti = self.nti.value(gdb.newest_frame())
      enumStrings = []
      val = int(self.val)
      i   = 0
      while val > 0:
        if (val & 1) == 1:
          enumStrings.append(reprEnum(i, nti))
        val = val >> 1
        i += 1

      return '{' + ', '.join(enumStrings) + '}'
    else:
      return str(int(self.val))

################################################################################

class NimHashSetPrinter:
  pattern = re.compile(r'^tyObject_(HashSet)__([A-Za-z0-9]*)$')

  def __init__(self, val):
    self.val = val

  def display_hint(self):
    return 'array'

  def to_string(self):
    counter  = 0
    capacity = 0
    if self.val:
      counter  = int(self.val['counter'])
      if self.val['data']:
        capacity = int(self.val['data']['Sup']['len'])

    return 'HashSet({0}, {1})'.format(counter, capacity)

  def children(self):
    if self.val:
      data = NimSeqPrinter(self.val['data'])
      for idxStr, entry in data.children():
        if int(entry['Field0']) > 0:
          yield ("data." + idxStr + ".Field1", str(entry['Field1']))

################################################################################

class NimSeqPrinter:
  # the pointer is explicity part of the type. So it is part of
  # ``pattern``.
  pattern = re.compile(r'^tySequence_\w* \*$')

  def __init__(self, val):
    self.val = val

  def display_hint(self):
    return 'array'

  def to_string(self):
    len = 0
    cap = 0
    if self.val:
      len = int(self.val['Sup']['len'])
      cap = int(self.val['Sup']['reserved'])

    return 'seq({0}, {1})'.format(len, cap)

  def children(self):
    if self.val:
      val = self.val
      valType = val.type
      length = int(val['Sup']['len'])

      if length <= 0:
        return

      dataType = valType['data'].type
      data = val['data']

      if self.val.type.name is None:
        dataType = valType['data'].type.target().pointer()
        data = val['data'].cast(dataType)

      inaccessible = False
      for i in range(length):
        if inaccessible:
          return
        try:
          str(data[i])
          yield "data[{0}]".format(i), data[i]
        except RuntimeError:
          inaccessible = True
          yield "data[{0}]".format(i), "inaccessible"