global Intern_String intern_empty;

global Intern_String intern_s64;
global Intern_String intern_s32;
global Intern_String intern_s16;
global Intern_String intern_s8;

global Intern_String intern_u64;
global Intern_String intern_u32;
global Intern_String intern_u16;
global Intern_String intern_u8;

global Intern_String intern_void;
global Intern_String intern_sizeu;

global Intern_String keyword_sizeof;
global Intern_String keyword_enum;
global Intern_String keyword_typedef;
global Intern_String keyword_struct;
global Intern_String keyword_union;
global Intern_String keyword_function;
global Intern_String keyword_global;

global AST_Node *type_s64;
global AST_Node *type_s32;
global AST_Node *type_s16;
global AST_Node *type_s8;

global AST_Node *type_u64;
global AST_Node *type_u32;
global AST_Node *type_u16;
global AST_Node *type_u8;

global AST_Node *type_void;
global AST_Node *type_sizeu;

function void
parser_init(Parser *p){
  p->interns_count = 4096;
  p->interns = arena_push_array(&p->intern_table_arena, Intern_String, p->interns_count);
  
  p->symbols_count = 4096;
  p->symbols = arena_push_array(&p->symbol_table_arena, AST_Node, p->symbols_count);
  
  keyword_sizeof = intern_string(p, lit("sizeof"));
  keyword_struct = intern_string(p, lit("struct"));
  keyword_enum = intern_string(p, lit("enum"));
  keyword_typedef = intern_string(p, lit("typedef"));
  keyword_union = intern_string(p, lit("union"));
  keyword_function = intern_string(p, lit("function"));
  keyword_global = intern_string(p, lit("global"));
  p->first_keyword = keyword_sizeof.s.str;
  p->last_keyword = keyword_global.s.str;
  
  
  intern_s64 = intern_string(p, lit("S64"));
  intern_s32 = intern_string(p, lit("S32"));
  intern_s16 = intern_string(p, lit("S16"));
  intern_s8 = intern_string(p, lit("S8"));
  
  intern_u64 = intern_string(p, lit("U64"));
  intern_u32 = intern_string(p, lit("U32"));
  intern_u16 = intern_string(p, lit("U16"));
  intern_u8  = intern_string(p, lit("U8"));
  
  intern_void = intern_string(p, lit("void"));
  intern_sizeu  = intern_string(p, lit("SizeU"));
  
  parser_push_scope(p); // Global scope
  
  type_s64 = symbol_register_basic_type(p, intern_s64, sizeof(S64));
  type_s32 = symbol_register_basic_type(p, intern_s32, sizeof(S32));
  type_s16 = symbol_register_basic_type(p, intern_s16, sizeof(S16));
  type_s8 = symbol_register_basic_type(p, intern_s8, sizeof(S8));
  
  type_u64 = symbol_register_basic_type(p, intern_u64, sizeof(U64));
  type_u32 = symbol_register_basic_type(p, intern_u32, sizeof(U32));
  type_u16 = symbol_register_basic_type(p, intern_u16, sizeof(U16));
  type_u8  = symbol_register_basic_type(p, intern_u8, sizeof(U8));
  
  type_void = symbol_register_basic_type(p, intern_void, sizeof(void));
  type_sizeu  = symbol_register_basic_type(p, intern_sizeu, sizeof(SizeU));
  
}

function B32
intern_is_keyword(Parser *p, Intern_String intern){
  if(intern.s.str >= p->first_keyword && intern.s.str <= p->last_keyword)
    return true;
  return false;
}

function void
parser_push_error(Parser *p, Token *token, char *str, ...){
  
  String string;
  {
    va_list args1, args2;
    va_start(args1, str);
    va_copy(args2, args1);
    string.len = vsnprintf(0, 0, str, args2);
    va_end(args2);
    
    string.str = arena_push_size(&p->main_arena, string.len + 1);
    vsnprintf((char*)string.str, string.len + 1, str, args1);
    va_end(args1);
  }
  
  lex_print("Error: %s\n", string.str);// @Todo(Krzosa): 
  Parser_Error *error = arena_push_struct(&p->main_arena, Parser_Error);
  error->message = string;
  error->next = 0;
  error->token = token;
  SLLQueuePush(p->first_error, p->last_error, error);
}

function void
intern_tokens(Parser *p){
  for(S64 i = 0; i < p->tokens.len; i++){
    Token *t = p->tokens.tokens + i;
    if(t->kind == TK_Identifier){
      t->intern_val = intern_string(p, t->string);
      if(intern_is_keyword(p, t->intern_val)){
        t->kind = TK_Keyword;
      }
    }
    else if(t->kind == TK_Error){
      parser_push_error(p, t, (char *)t->error_val.str);
    }
  }
}

//-----------------------------------------------------------------------------
// 
//-----------------------------------------------------------------------------
typedef struct Table_Index{
  U64 hash;
  U64 index;
  U64 iter;
  U64 max_size;
}Table_Index;

function Table_Index
table_index_from_hash(U64 hash, U64 max_size){
  Table_Index result = {0};
  result.hash = hash;
  result.index = result.hash % max_size;
  result.iter = result.index;
  result.max_size = max_size;
  return result;
}

function Table_Index
table_index_from_string(String string, U64 max_size){
  U64 hash = hash_fnv(string);
  Table_Index result = table_index_from_hash(hash, max_size);
  return result;
}

function B32
table_index_advance(Table_Index *index){
  index->iter = wrap_around_pow2(index->iter + 1, index->max_size);
  B32 result = index->iter == index->index;
  return result;
}

function Intern_String
intern_string(Parser *p, String string){
  Intern_String result = {};
  Table_Index index = table_index_from_string(string, p->interns_count);
  for(;;){
    Intern_String *intern = p->interns + index.iter;
    if(intern->s.str == 0){
      result.s = arena_push_string_copy(&p->main_arena, string);
      p->interns_in_bytes += string.len;
      p->interns_inserted += 1;
      *intern = result;
      break;
    }
    else if(string_compare(intern->s, string)){
      result = *intern;
      break;
    }
    
    if (table_index_advance(&index)) 
      break;
    
  }
  
  return result;
}

//-----------------------------------------------------------------------------
// Symbols
//-----------------------------------------------------------------------------
function AST_Node *
symbol_alloc_slot(Parser *p, Intern_String string, B32 is_global){
  Table_Index index = table_index_from_string(string.s, p->symbols_count);
  for(;;){
    AST_Node *symbol = p->symbols + index.iter;
    
    if(symbol->name.s.str == 0){
      /* @Note(Krzosa): Push on scope */ {
        if(is_global){
          SLLQueuePushMod(p->scope_stack->first, p->scope_stack->last, symbol, next_scope);
        }
        else{
          SLLQueuePushMod(p->global_scope->first, p->global_scope->last, symbol, next_scope);
        }
      }
      symbol->name = string;
      p->symbols_inserted++;
      
      return symbol;
    }
    else if(intern_compare(symbol->name, string)){
      return symbol;
    }
    
    if (table_index_advance(&index)) 
      break;
  }
  
  assert_msg(0, "Ran out of slots in symbol table");
  return 0;
}

function AST_Node *
symbol_lookup(Parser *p, Intern_String string){
  Table_Index index = table_index_from_string(string.s, p->symbols_count);
  for(;;){
    AST_Node *symbol = p->symbols + index.iter;
    
    if(symbol->name.s.str == 0){
      return 0;
    }
    else if(intern_compare(symbol->name, string)){
      return symbol;
    }
    
    if (table_index_advance(&index)) 
      return 0;
  }
}

function AST_Node *
symbol_register_basic_type(Parser *p, Intern_String string, SizeU size){
  AST_Node *node = symbol_alloc_slot(p, string, true);
  assert(node->kind == AK_None);
  node->kind = AK_BaseType;
  node->base_type_size = size;
  return node;
}

function void
symbol_register(Parser *p, AST_Node *node){
  AST_Node *look = symbol_alloc_slot(p, node->name, false);
  if(look->kind == AK_None){
    ast_copy_symbol(look, node);
  }
  else if(look->kind == node->kind){
    if(look->kind == AK_Enum ||
       look->kind == AK_Function ||
       look->kind == AK_Union ||
       look->kind == AK_Struct){
      if(look->first_child == 0){
        ast_copy_symbol(look, node);
      }
      else {
        parser_push_error(p, token_get(p), "Symbol already has a body");
      }
    }
    else {
      parser_push_error(p, token_get(p), "Trying to register a symbol again");
    }
  }
  else{
    parser_push_error(p, token_get(p), "Trying to register a symbol of different kind with the same name");
  }
}

function AST_Node *
symbol_lookup_type(Parser *p, Intern_String string){
  AST_Node *node = symbol_lookup(p, string);
  if(node){
    if(ast_is_type(node)){
      return node;
    }
  }
  return 0;
}

function AST_Node *
symbol_require_type(Parser *p, Token *token){
  AST_Node *result = symbol_lookup_type(p, token->intern_val);
  if(!result){
    parser_push_error(p, token, "Undefined type");
  }
  return result;
}

function void
parser_push_scope(Parser *p){
  Scope *scope = 0;
  SLLStackPop(p->scope_free_list, scope);
  if(!scope){
    scope = arena_push_struct(&p->main_arena, Scope);
  }
  SLLStackPush(p->scope_stack, scope);
  if(p->global_scope == 0){
    p->global_scope = scope;
  }
}

function void
parser_pop_scope(Parser *p){
  Scope *scope = 0;
  SLLStackPop(p->scope_stack, scope);
  assert(scope);
  
  for(AST_Node *s = scope->first; s; s=s->next_scope){
    memory_zero(s, sizeof(AST_Node));
    p->symbols_inserted--;
  }
  memory_zero(scope, sizeof(Scope));
  SLLStackPush(p->scope_free_list, scope);
}