#!/usr/bin/env python

# This script generates the necessary files to coordinate function calls between the FE 
# and BE. In the FE, this creates a mapping between function signature (Operation & 
# Arguments) to an opcode. The opcode is a thrift enum which is passed to the backend. 
# The backend has all the information from just the opcode and does not need to worry 
# about type checking.
#
# This scripts pulls function metadata input from 
#   - impala/common/impala_functions.py (manually maintained)
#   - impala/common/generated_functions.py (auto-generated metadata)
#
# This script will generate 4 outputs
#  1. Thrift enum for all the opcodes
#  - impala/fe/src/thrift/Opcodes.thrift
#  2. FE java operators (one per function, ignoring overloading)
#  - impala/fe/target/generated-sources/gen-java/com/cloudera/impala/opcode/FunctionOperater.java
#  3  Java registry setup (registering all the functions with signatures)
#  - impala/fe/target/generated-sources/gen-java/com/cloudera/impala/opcode/FunctionRegistry.java
#  4. BE registry setup (mapping opcodes to ComputeFunctions)
#  - impala/be/generated-sources/opcode/opcode-registry-init.cc
#
# TODO: version the registry on the FE and BE so we can identify if they are out of sync

import sys
import os
from string import Template
import impala_functions
import generated_functions

native_types = {
  'BOOLEAN'       : 'bool',
  'TINYINT'       : 'char',
  'SMALLINT'      : 'short',
  'INT'           : 'int',
  'BIGINT'        : 'long',
  'FLOAT'         : 'float',
  'DOUBLE'        : 'double',
  'STRING'        : 'StringValue',
}

thrift_preamble = '\
// Copyright (c) 2011 Cloudera, Inc. All rights reserved.\n\
// This is a generated file, DO NOT EDIT.\n\
// To add new functions, see impala/common/gen_opcodes.py\n\
\n\
namespace cpp impala\n\
namespace java com.cloudera.impala.thrift\n\
\n\
enum TExprOpcode {\n'

thrift_epilogue = '\
}\n\
\n'

cc_registry_preamble = '\
// Copyright (c) 2011 Cloudera, Inc. All rights reserved.\n\
// This is a generated file, DO NOT EDIT.\n\
// To add new functions, see impala/common/gen_opcodes.py\n\
\n\
#include "exprs/opcode-registry.h"\n\
#include "exprs/expr.h"\n\
#include "exprs/compound-predicate.h"\n\
#include "exprs/like-predicate.h"\n\
#include "exprs/math-functions.h"\n\
#include "exprs/string-functions.h"\n\
#include "opcode/functions.h"\n\
\n\
namespace impala { \n\
\n\
void OpcodeRegistry::Init() {\n'

cc_registry_epilogue = '\
}\n\
\n\
}\n'

operator_file_preamble = '\
// Copyright (c) 2011 Cloudera, Inc. All rights reserved.\n\
// This is a generated file, DO NOT EDIT.\n\
// To add new functions, see impala/common/gen_opcodes.py\n\
\n\
package com.cloudera.impala.opcode;\n\
\n\
public enum FunctionOperator {\n'

operator_file_epilogue = '\
}\n'

java_registry_preamble = '\
// Copyright (c) 2011 Cloudera, Inc. All rights reserved.\n\
// This is a generated file, DO NOT EDIT.\n\
// To add new functions, see impala/common/gen_opcodes.py\n\
\n\
package com.cloudera.impala.opcode;\n\
\n\
import com.cloudera.impala.analysis.OpcodeRegistry;\n\
import com.cloudera.impala.catalog.PrimitiveType;\n\
import com.cloudera.impala.thrift.TExprOpcode;\n\
import com.google.common.base.Preconditions;\n\
\n\
public class FunctionRegistry { \n\
  public static void InitFunctions(OpcodeRegistry registry) { \n\
    boolean result = true;\n\
\n'

java_registry_epilogue = '\
    Preconditions.checkState(result); \n\
  }\n\
}\n'


def initialize_sub(op, return_type, arg_types):
  sub = {}
  java_args = "PrimitiveType." + return_type 
  sub["fn_class"] = "GetValueFunctions"
  sub["fn_signature"] = op
  sub["num_args"] = len(arg_types)
  for idx in range(0, len(arg_types)):
    arg = arg_types[idx]
    sub["fn_signature"] += "_" + native_types[arg]
    sub["native_type" + repr(idx + 1)] = native_types[arg]
    java_args += ", PrimitiveType." + arg
  sub["thrift_enum"] = sub["fn_signature"].upper()
  sub["java_output"] = "FunctionOperator." + op.upper() + ", TExprOpcode." + sub["thrift_enum"] 
  sub["java_output"] += ", " + java_args
  return sub

FE_PATH = "../../fe/generated-sources/gen-java/com/cloudera/impala/opcode/"
BE_PATH = "../../be/generated-sources/opcode/"
THRIFT_PATH = "../thrift/"

# This contains a list of all the opcodes that are built base on the
# function name from the input.  Inputs can have multiple signatures
# with the same function name and the opcode is mangled using the
# arg types.
opcodes = []

# This contains a list of all the function names (no overloading/mangling)
operators = []

# This is a mapping of operators to a list of function meta data entries
# Each meta data entry is itself a map to store all the meta data
#   - fn_name, ret_type, args, be_fn, sql_names
meta_data_entries = {}

# Read in the function and add it to the meta_data_entries map
def add_function(fn_meta_data):
  fn_name = fn_meta_data[0]
  ret_type = fn_meta_data[1]
  args = fn_meta_data[2]
  be_fn = fn_meta_data[3]

  entry = {}
  entry["fn_name"] = fn_meta_data[0]
  entry["ret_type"] = fn_meta_data[1]
  entry["args"] = fn_meta_data[2]
  entry["be_fn"] = fn_meta_data[3]
  entry["sql_names"] = fn_meta_data[4]

  if fn_name in meta_data_entries:
    meta_data_entries[fn_name].append(entry)
  else:
    fn_list = [entry]
    meta_data_entries[fn_name] = fn_list
    operators.append(fn_name.upper())
  
# Iterate over entries in the meta_data_entries map and generate opcodes.  Some
# entries will have the same name at this stage, quality the name withe the
# signature  to generate unique enums.
# Resulting opcode list is sorted with INVALID_OPCODE at beginning and LAST_OPCODE 
# at end.
def generate_opcodes():
  for fn in meta_data_entries:
    entries = meta_data_entries[fn]
    if len(entries) > 1:
      for entry in entries:
        opcode = fn.upper()
        for arg in entry["args"]:
          opcode += "_" + native_types[arg].upper()
        opcodes.append(opcode)
        entry["opcode"] = opcode
    else:
      opcodes.append(fn.upper())
      entries[0]["opcode"] = fn.upper()
  opcodes.sort()
  opcodes.insert(0, 'INVALID_OPCODE')
  opcodes.append('LAST_OPCODE')

# Generates the BE registry init file that will add all the compute functions
# to the registry.  Outputs the generated-file to 'filename'
def generate_be_registry_init(filename):
  cc_registry_file = open(filename, "w")
  cc_registry_file.write(cc_registry_preamble)
  
  for fn in meta_data_entries:
    entries = meta_data_entries[fn]
    for entry in entries:
      opcode = entry["opcode"]
      be_fn = entry["be_fn"]
      cc_registry_file.write("  this->Add(TExprOpcode::%s, %s);\n" % (opcode, be_fn))

  cc_registry_file.write(cc_registry_epilogue)
  cc_registry_file.close()

# Generates the FE registry init file that registers all the functions.  This file
# contains all the opcode->function signature mappings and all of the string->operator
# mappings for sql functions
def generate_fe_registry_init(filename):
  java_registry_file = open(filename, "w")
  java_registry_file.write(java_registry_preamble)

  for fn in meta_data_entries:
    entries = meta_data_entries[fn]
    for entry in entries:
      java_output = "FunctionOperator." + fn.upper()
      java_output += ", TExprOpcode." + entry["opcode"]
      java_output += ", PrimitiveType." + entry["ret_type"]
      for arg in entry["args"]:
        java_output += ", PrimitiveType." + arg
      java_registry_file.write("    result &= registry.add(%s);\n" % java_output)
  java_registry_file.write("\n")
  
  mappings = {}

  for fn in meta_data_entries:
    entries = meta_data_entries[fn]
    for entry in entries:
      for name in entry["sql_names"]:
        if name in mappings:
          if mappings[name] != fn.upper():
            print "Invalid mapping \"%s\" -> FunctionOperator.%s." % (name, mappings[name])
            print "There is already a mapping \"%s\" -> FunctionOperator.%s.\n" % (name, fn.upper())
            sys.exit(1)
          continue
        mappings[name] = fn.upper()
        java_output = "\"%s\", FunctionOperator.%s" % (name, fn.upper())
        java_registry_file.write("    result &= registry.addFunctionMapping(%s);\n" % java_output)
  java_registry_file.write("\n")

  java_registry_file.write(java_registry_epilogue)
  java_registry_file.close()

# Read the function metadata inputs
for function in impala_functions.functions:
  if len(function) != 5:
    print "Invalid function entry in impala_functions.py:\n\t" + repr(function)
    sys.exit(1)
  add_function(function)
for function in generated_functions.functions:
  if len(function) != 5:
    print "Invalid function entry in generated_functions.py:\n\t" + repr(function)
    sys.exit(1)
  add_function(function)

generate_opcodes()

if not os.path.exists(BE_PATH):
  os.makedirs(BE_PATH)
if not os.path.exists(FE_PATH):
  os.makedirs(FE_PATH)
if not os.path.exists(THRIFT_PATH):
  os.makedirs(THRIFT_PATH)

generate_be_registry_init(BE_PATH + "opcode-registry-init.cc")
generate_fe_registry_init(FE_PATH + "FunctionRegistry.java")

# Output the opcodes to thrift
thrift_file = open(THRIFT_PATH + "Opcodes.thrift", "w")
thrift_file.write(thrift_preamble)
for opcode in opcodes:
  thrift_file.write("  %s,\n" % opcode)
thrift_file.write(thrift_epilogue)
thrift_file.close()

# Output the operators to java
operators.sort()
operators.insert(0, "INVALID_OPERATOR")
operator_java_file = open(FE_PATH + "FunctionOperator.java", "w")
operator_java_file.write(operator_file_preamble)
for op in operators:
  operator_java_file.write("  %s,\n" % op)
operator_java_file.write(operator_file_epilogue)
operator_java_file.close()