# fakegen.rb
# A simple code generator to create some C macros for defining test fake functions


$cpp_output = true
$MAX_ARGS = 20
$DEFAULT_ARG_HISTORY = 50
$MAX_CALL_HISTORY = 50

def include_dependencies
  putd "#include <stdarg.h>"
  putd "#include <string.h> /* For memset and memcpy */"
  puts
end

def output_constants
  putd "#define FFF_MAX_ARGS (#{$MAX_ARGS}u)"
  putd "#ifndef FFF_ARG_HISTORY_LEN"
  indent {
    putd "#define FFF_ARG_HISTORY_LEN (#{$DEFAULT_ARG_HISTORY}u)"
  }
  putd "#endif"
  putd "#ifndef FFF_CALL_HISTORY_LEN"
  indent {
    putd "#define FFF_CALL_HISTORY_LEN (#{$MAX_CALL_HISTORY}u)"
  }
  putd "#endif"
end





# ------  Helper macros to use internally ------ #
def output_internal_helper_macros
  putd "/* -- INTERNAL HELPER MACROS -- */"
  
  define_return_sequence_helper
  define_custom_fake_sequence_helper
  define_reset_fake_macro
  define_declare_arg_helper
  define_declare_all_func_common_helper
  define_save_arg_helper
  define_room_for_more_history
  define_save_arg_history_helper
  define_history_dropped_helper
  define_value_function_variables_helper
  define_custom_fake_seq_variables_helper
  define_increment_call_count_helper
  define_return_fake_result_helper
  define_extern_c_helper
  define_reset_fake_helper
  
  putd "/* -- END INTERNAL HELPER MACROS -- */"
  puts
end

def define_return_sequence_helper
  putd_backslash "#define SET_RETURN_SEQ(FUNCNAME, ARRAY_POINTER, ARRAY_LEN)"
  indent {
    putd_backslash "FUNCNAME##_fake.return_val_seq = ARRAY_POINTER;"
    putd "FUNCNAME##_fake.return_val_seq_len = ARRAY_LEN;"
  }
end

def define_custom_fake_sequence_helper
  putd_backslash "#define SET_CUSTOM_FAKE_SEQ(FUNCNAME, ARRAY_POINTER, ARRAY_LEN)"
  indent {
    putd_backslash "FUNCNAME##_fake.custom_fake_seq = ARRAY_POINTER;"
    putd "FUNCNAME##_fake.custom_fake_seq_len = ARRAY_LEN;"
  }
end

def define_reset_fake_macro
  puts
  putd "/* Defining a function to reset a fake function */"
  putd_backslash "#define RESET_FAKE(FUNCNAME) {"
  indent {
    putd_backslash "FUNCNAME##_reset();"
  }
  putd_backslash "}"
  puts
end

def define_declare_arg_helper
  puts
  putd_backslash "#define DECLARE_ARG(type, n, FUNCNAME)"
  indent {
    putd_backslash "type arg##n##_val;"
    putd "type arg##n##_history[FFF_ARG_HISTORY_LEN];"
  }
end

def define_declare_all_func_common_helper
  puts
  putd_backslash "#define DECLARE_ALL_FUNC_COMMON"
  indent {
    putd_backslash "unsigned int call_count;"
    putd_backslash "unsigned int arg_history_len;"
    putd_backslash "unsigned int arg_histories_dropped;"
  }
end

def define_save_arg_helper
  puts
  putd_backslash "#define SAVE_ARG(FUNCNAME, n)"
  indent {
    putd "memcpy((void*)&FUNCNAME##_fake.arg##n##_val, (void*)&arg##n, sizeof(arg##n));"
  }
end

def define_room_for_more_history
  puts
  putd_backslash "#define ROOM_FOR_MORE_HISTORY(FUNCNAME)"
  indent {
    putd "FUNCNAME##_fake.call_count < FFF_ARG_HISTORY_LEN"
  }
end

def define_save_arg_history_helper
  puts
  putd_backslash "#define SAVE_ARG_HISTORY(FUNCNAME, ARGN)"
  indent {
    putd "memcpy((void*)&FUNCNAME##_fake.arg##ARGN##_history[FUNCNAME##_fake.call_count], (void*)&arg##ARGN, sizeof(arg##ARGN));"
  }
end

def define_history_dropped_helper
  puts
  putd_backslash "#define HISTORY_DROPPED(FUNCNAME)"
  indent {
    putd "FUNCNAME##_fake.arg_histories_dropped++"
  }
end

def define_value_function_variables_helper
  puts
  putd_backslash "#define DECLARE_VALUE_FUNCTION_VARIABLES(RETURN_TYPE)"
  indent {
    putd_backslash "RETURN_TYPE return_val;" 
    putd_backslash "int return_val_seq_len;" 
    putd_backslash "int return_val_seq_idx;" 
    putd_backslash "RETURN_TYPE * return_val_seq;"
  }
end

def define_custom_fake_seq_variables_helper
  puts
  putd_backslash "#define DECLARE_CUSTOM_FAKE_SEQ_VARIABLES"
  indent {
    putd_backslash "int custom_fake_seq_len;"
    putd_backslash "int custom_fake_seq_idx;"
  }
end

def define_increment_call_count_helper
  puts
  putd_backslash "#define INCREMENT_CALL_COUNT(FUNCNAME)"
  indent {
    putd "FUNCNAME##_fake.call_count++"
  }
end

def define_return_fake_result_helper
  puts
  putd_backslash "#define RETURN_FAKE_RESULT(FUNCNAME)"
  indent {
    putd_backslash "if (FUNCNAME##_fake.return_val_seq_len){ /* then its a sequence */"
    indent {
      putd_backslash "if(FUNCNAME##_fake.return_val_seq_idx < FUNCNAME##_fake.return_val_seq_len) {"
      indent {
        putd_backslash "return FUNCNAME##_fake.return_val_seq[FUNCNAME##_fake.return_val_seq_idx++];"
      }
      putd_backslash "}"
      putd_backslash "return FUNCNAME##_fake.return_val_seq[FUNCNAME##_fake.return_val_seq_len-1]; /* return last element */"
    }
    putd_backslash "}"
    putd_backslash "return FUNCNAME##_fake.return_val;"
  }
end

def define_extern_c_helper
  puts
  putd "#ifdef __cplusplus"
  indent {
    putd "#define FFF_EXTERN_C extern \"C\"{" 
    putd "#define FFF_END_EXTERN_C } " 
  }
  putd "#else  /* ansi c */"
  indent {
    putd "#define FFF_EXTERN_C "
    putd "#define FFF_END_EXTERN_C "
  }
  putd "#endif  /* cpp/ansi c */"
end

def define_reset_fake_helper
  puts
  putd_backslash "#define DEFINE_RESET_FUNCTION(FUNCNAME)"
  indent {
    putd_backslash "void FUNCNAME##_reset(){"
    indent {
      putd_backslash "memset(&FUNCNAME##_fake, 0, sizeof(FUNCNAME##_fake));"
      putd_backslash "FUNCNAME##_fake.arg_history_len = FFF_ARG_HISTORY_LEN;"
    }
    putd "}"
  }
end
# ------  End Helper macros ------ #

#fakegen helpers to print at levels of indentation
$current_depth = 0
def putd(str)
  $current_depth.times {|not_used| print " "}
  puts str
end

#multiline putd which adds a \ at the end of the generated macro
def putd_backslash str
  putd(str + " \\")
end

def pushd
  $current_depth = $current_depth + 4
end

def popd
  $current_depth = $current_depth - 4
end

def indent
  pushd 
    yield
  popd
end

def output_macro(arg_count, has_varargs, is_value_function)

  vararg_name = has_varargs ? "_VARARG" : ""
  fake_macro_name = is_value_function ? "FAKE_VALUE_FUNC#{arg_count}#{vararg_name}" : "FAKE_VOID_FUNC#{arg_count}#{vararg_name}"
  declare_macro_name = "DECLARE_#{fake_macro_name}"
  define_macro_name = "DEFINE_#{fake_macro_name}"
  saved_arg_count = arg_count - (has_varargs ? 1 : 0)
  return_type = is_value_function ? "RETURN_TYPE" : ""

  puts
  output_macro_header(declare_macro_name, saved_arg_count, has_varargs, return_type)
  indent {
    extern_c {  # define argument capture variables
      output_variables(saved_arg_count, has_varargs, is_value_function)
    }
  }
  
  puts
  output_macro_header(define_macro_name, saved_arg_count, has_varargs, return_type)
  indent {
    extern_c {
      putd_backslash "FUNCNAME##_Fake FUNCNAME##_fake;"
      putd_backslash function_signature(saved_arg_count, has_varargs, is_value_function) + "{"
      indent {
        output_function_body(saved_arg_count, has_varargs, is_value_function)
      }
      putd_backslash "}"
      putd_backslash "DEFINE_RESET_FUNCTION(FUNCNAME)"
    }
  }
  
  puts
  
  output_macro_header(fake_macro_name, saved_arg_count, has_varargs, return_type)
  indent {
    putd macro_signature_for(declare_macro_name, saved_arg_count, has_varargs, return_type)
    putd macro_signature_for(define_macro_name, saved_arg_count, has_varargs, return_type)
    puts
  }
end

def output_macro_header(macro_name, arg_count, has_varargs, return_type)
  output_macro_name(macro_name, arg_count, has_varargs, return_type)
end

# #define #macro_name(RETURN_TYPE, FUNCNAME, ARG0,...)
def output_macro_name(macro_name, arg_count, has_varargs, return_type)
  putd "#define " + macro_signature_for(macro_name, arg_count, has_varargs, return_type)
end

# #macro_name(RETURN_TYPE, FUNCNAME, ARG0,...) \
def macro_signature_for(macro_name, arg_count, has_varargs, return_type)
  parameter_list = "#{macro_name}("
  if return_type != ""
    parameter_list += return_type
    parameter_list += ", "
  end
  parameter_list += "FUNCNAME"

  arg_count.times { |i| parameter_list += ", ARG#{i}_TYPE" }

  parameter_list += ", ..." if has_varargs

  parameter_list +=  ") \\"
  
  parameter_list
end

def output_variables(arg_count, has_varargs, is_value_function)
  in_struct{
    arg_count.times { |argN| 
      putd_backslash "DECLARE_ARG(ARG#{argN}_TYPE, #{argN}, FUNCNAME)"
    }
    putd_backslash "DECLARE_ALL_FUNC_COMMON"
    putd_backslash "DECLARE_VALUE_FUNCTION_VARIABLES(RETURN_TYPE)" unless not is_value_function
    putd_backslash "DECLARE_CUSTOM_FAKE_SEQ_VARIABLES"
    output_custom_function_signature(arg_count, has_varargs, is_value_function)
    output_custom_function_array(arg_count, has_varargs, is_value_function)
  }
  putd_backslash "extern FUNCNAME##_Fake FUNCNAME##_fake;"
  putd_backslash "void FUNCNAME##_reset();"
end

#example: ARG0_TYPE arg0, ARG1_TYPE arg1
def arg_val_list(args_count)
  arguments = []
  args_count.times { |i| arguments << "ARG#{i}_TYPE arg#{i}" }
  arguments.join(", ")
end

#example: arg0, arg1
def arg_list(args_count)
  arguments = []
  args_count.times { |i| arguments << "arg#{i}" }
  arguments.join(", ")
end

# RETURN_TYPE (*custom_fake)(ARG0_TYPE arg0);\
# void (*custom_fake)(ARG0_TYPE arg0, ARG1_TYPE arg1, ARG2_TYPE arg2);\
def output_custom_function_signature(arg_count, has_varargs, is_value_function)
  return_type = is_value_function ? "RETURN_TYPE" : "void"
  ap_list = has_varargs ? ", va_list ap" : ""
  signature = "(*custom_fake)(#{arg_val_list(arg_count)}#{ap_list});"
  putd_backslash return_type + signature
end

def output_custom_function_array(arg_count, has_varargs, is_value_function)
  return_type = is_value_function ? "RETURN_TYPE" : "void"
  ap_list = has_varargs ? ", va_list ap" : ""
  custom_array = "(**custom_fake_seq)(#{arg_val_list(arg_count)}#{ap_list});"
  putd_backslash return_type + custom_array
end

# example: RETURN_TYPE FUNCNAME(ARG0_TYPE arg0, ARG1_TYPE arg1)
def function_signature(arg_count, has_varargs, is_value_function)
  return_type = is_value_function ? "RETURN_TYPE" : "void"
  varargs = has_varargs ? ", ..." : ""
  "#{return_type} FUNCNAME(#{arg_val_list(arg_count)}#{varargs})"
end

def output_function_body(arg_count, has_varargs, is_value_function)
  arg_count.times { |i| putd_backslash "SAVE_ARG(FUNCNAME, #{i});" }
  putd_backslash "if(ROOM_FOR_MORE_HISTORY(FUNCNAME)){"
  indent {
    arg_count.times { |i| putd_backslash "SAVE_ARG_HISTORY(FUNCNAME, #{i});" }
  }
  putd_backslash "}"
  putd_backslash "else{"
  indent {
    putd_backslash "HISTORY_DROPPED(FUNCNAME);"
  }
  putd_backslash "}"
  putd_backslash "INCREMENT_CALL_COUNT(FUNCNAME);"
  putd_backslash "REGISTER_CALL(FUNCNAME);"

  if has_varargs
    putd_backslash "if(FUNCNAME##_fake.custom_fake){"
    indent {
      putd_backslash "RETURN_TYPE ret;" if is_value_function
      putd_backslash "va_list ap;"
      putd_backslash "va_start(ap, arg#{arg_count-1});"
    }
    custom_fake_call = "FUNCNAME##_fake.custom_fake(#{arg_list(arg_count)}, ap);"
    indent {
      if is_value_function
        putd_backslash "ret = #{custom_fake_call}"
      else
        putd_backslash "#{custom_fake_call}"
      end
      putd_backslash "va_end(ap);"
      putd_backslash "return ret;" if is_value_function
    }
    putd_backslash "}"
  else
    return_type = is_value_function ? "return " : ""
    putd_backslash "if (FUNCNAME##_fake.custom_fake_seq_len){ /* a sequence of custom fakes */"
    indent {
      putd_backslash "if (FUNCNAME##_fake.custom_fake_seq_idx < FUNCNAME##_fake.custom_fake_seq_len){"
      indent {
        putd_backslash "#{return_type}FUNCNAME##_fake.custom_fake_seq[FUNCNAME##_fake.custom_fake_seq_idx++](#{arg_list(arg_count)});"
      }
      putd_backslash "}"
      putd_backslash "else{"
      indent {
        putd_backslash "#{return_type}FUNCNAME##_fake.custom_fake_seq[FUNCNAME##_fake.custom_fake_seq_len-1](#{arg_list(arg_count)});"
      }
      putd_backslash "}"
    }
    putd_backslash "}"
    putd_backslash "if (FUNCNAME##_fake.custom_fake) #{return_type}FUNCNAME##_fake.custom_fake(#{arg_list(arg_count)});"
  end

  putd_backslash "RETURN_FAKE_RESULT(FUNCNAME)" if is_value_function
end

def define_fff_globals
  putd "typedef struct { "
  indent {
    putd "void * call_history[FFF_CALL_HISTORY_LEN];"
    putd "unsigned int call_history_idx;"
  }
  putd "} fff_globals_t;"
  puts
  putd_backslash "FFF_EXTERN_C"
  putd "extern fff_globals_t fff;"
  putd_backslash "FFF_END_EXTERN_C"
  puts
  putd_backslash "#define DEFINE_FFF_GLOBALS"
  indent {
    putd_backslash "FFF_EXTERN_C"
    indent {
      putd_backslash "fff_globals_t fff;"
    }
    putd "FFF_END_EXTERN_C"
  }
  puts
  putd "#define FFF_RESET_HISTORY() fff.call_history_idx = 0;"
  puts
  putd_backslash "#define REGISTER_CALL(function)"
  indent {
    putd_backslash "if(fff.call_history_idx < FFF_CALL_HISTORY_LEN)"
    indent {
      putd "fff.call_history[fff.call_history_idx++] = (void *)function;"
    }
  }
end

def extern_c
  putd_backslash "FFF_EXTERN_C"
  indent { 
    yield
  }
  putd_backslash "FFF_END_EXTERN_C"
end

def in_struct
  putd_backslash "typedef struct FUNCNAME##_Fake {"
  indent {
    yield
  }
  putd_backslash "} FUNCNAME##_Fake;"
end

def include_guard
  putd "#ifndef FAKE_FUNCTIONS"
  putd "#define FAKE_FUNCTIONS"
  puts

  yield

  puts
  putd "#endif /* FAKE_FUNCTIONS */"
end

def generate_arg_sequence(args, prefix, do_reverse, joinstr) 
 fmap = (0..args).flat_map {|i| [prefix + i.to_s]}
 if do_reverse then fmap.reverse.join(joinstr) else fmap.join(", ") end
end

def counting_macro_instance(type, vararg = :non_vararg, prefix = "")
  appendix = (vararg == :vararg) ? "_VARARG" : ""
  minus_count = (type == :VOID) ? 1 : 2

  <<-MACRO_COUNTING_INSTANCE
#define #{prefix}FAKE_#{type.to_s}_FUNC#{appendix}(...) \
    #{prefix}FUNC_#{type.to_s}#{appendix}_(PP_NARG_MINUS#{minus_count}(__VA_ARGS__), __VA_ARGS__)

#define #{prefix}FUNC_#{type.to_s}#{appendix}_(N,...) \
    #{prefix}FUNC_#{type.to_s}#{appendix}_N(N,__VA_ARGS__)

#define #{prefix}FUNC_#{type.to_s}#{appendix}_N(N,...) \
    #{prefix}FAKE_#{type.to_s}_FUNC ## N#{" ## _VARARG" if vararg == :vararg}(__VA_ARGS__)

  MACRO_COUNTING_INSTANCE
end

def output_macro_counting_shortcuts
  putd <<-MACRO_COUNTING

#define PP_NARG_MINUS2(...) \
    PP_NARG_MINUS2_(__VA_ARGS__, PP_RSEQ_N_MINUS2())

#define PP_NARG_MINUS2_(...) \
    PP_ARG_MINUS2_N(__VA_ARGS__)

#define PP_ARG_MINUS2_N(returnVal, #{generate_arg_sequence($MAX_ARGS, '_', false, ", ")}, N, ...)   N

#define PP_RSEQ_N_MINUS2() \
    #{generate_arg_sequence($MAX_ARGS, '', true, ',')}


#define PP_NARG_MINUS1(...) \
    PP_NARG_MINUS1_(__VA_ARGS__, PP_RSEQ_N_MINUS1())

#define PP_NARG_MINUS1_(...) \
    PP_ARG_MINUS1_N(__VA_ARGS__)

#define PP_ARG_MINUS1_N(#{generate_arg_sequence($MAX_ARGS, '_', false, ", ")}, N, ...)   N

#define PP_RSEQ_N_MINUS1() \
    #{generate_arg_sequence($MAX_ARGS, '', true, ',')}



/* DECLARE AND DEFINE FAKE FUNCTIONS - PLACE IN TEST FILES */

#{counting_macro_instance(:VALUE)}
#{counting_macro_instance(:VOID)}
#{counting_macro_instance(:VALUE, :vararg)}
#{counting_macro_instance(:VOID, :vararg)}

/* DECLARE FAKE FUNCTIONS - PLACE IN HEADER FILES */

#{counting_macro_instance(:VALUE, :non_vararg, "DECLARE_")}
#{counting_macro_instance(:VOID, :non_vararg, "DECLARE_")}
#{counting_macro_instance(:VALUE, :vararg, "DECLARE_")}
#{counting_macro_instance(:VOID, :vararg, "DECLARE_")}

/* DEFINE FAKE FUNCTIONS - PLACE IN SOURCE FILES */

#{counting_macro_instance(:VALUE, :non_vararg, "DEFINE_")}
#{counting_macro_instance(:VOID, :non_vararg, "DEFINE_")}
#{counting_macro_instance(:VALUE, :vararg, "DEFINE_")}
#{counting_macro_instance(:VOID, :vararg, "DEFINE_")}

  MACRO_COUNTING
end

def output_c_and_cpp

  include_guard {
    include_dependencies
    output_constants
    output_internal_helper_macros
    yield
    output_macro_counting_shortcuts
  }
end

# lets generate!!
output_c_and_cpp{
  define_fff_globals
  # Create fake generators for 0..MAX_ARGS
  num_fake_generators = $MAX_ARGS + 1
  num_fake_generators.times {|arg_count| output_macro(arg_count, false, false)}
  num_fake_generators.times {|arg_count| output_macro(arg_count, false, true)}
  # generate the varargs variants
  (2..$MAX_ARGS).each {|arg_count| output_macro(arg_count, true, false)}
  (2..$MAX_ARGS).each {|arg_count| output_macro(arg_count, true, true)}
}