#define gen(...) pctx->gen.addf(__VA_ARGS__)
#define genln(...) do{gen("\n"); gen_indent(); gen(__VA_ARGS__); }while(0)
global S32 global_indent;
global S32 is_inside_struct;

function void
gen_indent(){
  for(S32 i = 0; i < global_indent; i++) gen("  ");
}

// @todo: Gen complicated decl
//array 10 ( pointer (pointer array 5 int a))
// int (*(*(a[5])))[10]
//
// 1 Get to the bottom
// 2 Add variable name
// 3 Going backwards add arrays and pointers in parens
// 4 Add type name on the left side

function void
gen_simple_decl_prefix(Ast_Resolved_Type *ast){
  switch(ast->kind){
    case TYPE_POINTER: gen_simple_decl_prefix(ast->base); gen("*"); break;
    case TYPE_ARRAY: gen_simple_decl_prefix(ast->base); break;
    case TYPE_LAMBDA:break;
    case TYPE_ENUM:
    case TYPE_STRUCT: {
      auto constant = (Ast_Const *)ast->ast->parent;
      auto name = constant->name;
      gen("%s ", name.str);
    }break;
    default: gen("%s ", name(ast));
  }
}

function void
gen_simple_decl_postfix(Ast_Resolved_Type *ast){
  switch(ast->kind){
    case TYPE_POINTER: gen_simple_decl_postfix(ast->base); break;
    case TYPE_ARRAY:
      gen("[");
      if(ast->arr.size != ARRAY_SIZE_INFERRED)
        gen("%d", (int)ast->arr.size);
      gen("]");
      gen_simple_decl_postfix(ast->arr.base); break;
    case TYPE_LAMBDA:break;
    case TYPE_ENUM: case TYPE_STRUCT:break;
    default: name(ast);
  }
}

function void
gen_simple_decl(Ast_Resolved_Type *ast, Intern_String name){
  if(ast->kind == TYPE_LAMBDA) {
    gen_simple_decl_prefix(ast->func.ret);
    gen("(*%s)(", name.str);
    For(ast->func.args){
      gen_simple_decl_prefix(it);
      if(&it != ast->func.args.end() - 1) gen(", ");
    }
    gen(")");
  }
  else{
    gen_simple_decl_prefix(ast);
    if(name.len) {
      gen("%s", name.str);
    }
    gen_simple_decl_postfix(ast);
  }
}

function void
gen_value(Value a){
  switch(a.type->kind){
    CASE_INT: {
      Scratch scratch;
      const char *string = bigint_to_error_string(scratch, &a.big_int_val, 10);
      gen("%s", string);
    }break;
    CASE_STRING: gen("LIT(\"%s\")", a.intern_val.str); break;
    CASE_BOOL: a.bool_val ? gen("true"):gen("false"); break;
    CASE_FLOAT: gen("%f", a.f64_val); break;
    invalid_default_case;
  }
}

function void
gen_expr(Ast_Expr *ast){
  switch(ast->kind){
    CASE(IDENT, Atom){
      gen("%s", node->intern_val.str);
      BREAK();
    }

    CASE(VALUE, Atom){
      gen_value(node->value);
      BREAK();
    }

    CASE(INDEX, Index){
      Sym *sym = resolved_get(node);
      if(is_array(sym->type)){
        gen("(");
        gen("(");

        gen("(");
        gen_simple_decl(sym->type->arr.base, {});
        gen("*)");
        gen_expr(node->expr);
        gen(".data)");


        gen("[");
        gen_expr(node->index);
        gen("]");
        gen(")");
      } else{
        gen("(");
        gen_expr(node->expr);
        gen("[");
        gen_expr(node->index);
        gen("]");
        gen(")");
      }
      BREAK();
    }

    CASE(BINARY, Binary){
      if(node->op == TK_Dot){
        Sym *sym = resolved_get(node->left);
        gen_expr(node->left);
        if(sym->type->kind == TYPE_POINTER) gen("->");
        else gen(".");
        gen_expr(node->right);
      }
      else if(node->op == TK_ColonAssign){

        Sym *sym = resolved_get(node);
        Ast_Atom *atom = (Ast_Atom *)node->left;
        assert(is_atom(atom));
        gen_simple_decl(sym->type, atom->intern_val);
        if(node->right){
          gen(" = ");
          gen_expr(node->right);
        }
      }
      else{
        if(!token_is_assign(node->op)) gen("(");
        gen_expr(node->left);
        gen("%s", name(node->op));
        gen_expr(node->right);
        if(!token_is_assign(node->op)) gen(")");
      }
      BREAK();
    }

    CASE(UNARY, Unary){
      gen("(");
      if(node->op != TK_PostIncrement && node->op != TK_PostDecrement) gen("%s", name(node->op));
      gen_expr(node->expr);
      if(node->op == TK_PostIncrement || node->op == TK_PostDecrement) gen("%s", name(node->op));
      gen(")");
      BREAK();
    }

    CASE(CAST, Cast){
      gen("(");
      gen("(");
      gen_simple_decl(resolved_type_get(node->typespec), {});
      gen(")");
      gen_expr(node->expr);
      gen(")");
      BREAK();
    }

    CASE(CALL, Call){
      // @todo: Reach into map instead of direct lookup
      if(is_struct(node->type) || is_array(node->type)){
        if(is_array(node->type)){
          gen("(Slice){%d, ", node->exprs.len);
        }
        gen("(");
        gen_simple_decl(node->type, {});
        gen(")");

        gen("{");
        For(node->exprs){
          auto comp = it;
          if(comp->name){
            gen(".");
            gen_expr(comp->name);
            gen(" = ");
          }
          if(comp->index){
            gen("[");
            gen_expr(comp->index);
            gen("] = ");
          }
          assert(comp->item);
          gen_expr(comp->item);

          if(!node->exprs.is_last(&it)) gen(", ");
        }
        gen("}");
        if(is_array(node->type)){
          gen("}");
        }
      }
      else{
        gen_expr(node->name);
        gen("(");
        auto name_for_printf = (Ast_Atom *)node->name;
        For(node->exprs){
          // @special_case @todo in the future this should be replaced
          // with []Any
          if(intern_printf == name_for_printf->intern_val && &it == node->exprs.data){
            Ast_Atom *atom = (Ast_Atom *)it->item;
            assert(atom->kind == AST_VALUE);
            assert(atom->type == untyped_string);
            gen("\"%s\"", atom->intern_val.str);
          }
          else gen_expr(it->item);
          if(!node->exprs.is_last(&it)) gen(", ");
        }
        gen(")");
      }

      BREAK();
    }

    invalid_default_case;
  }
}

function void
gen_line(Ast *node){
  if(emit_line_directives)
    genln("#line %d", node->pos->line+1);
}

function void
gen_ast(Ast *ast);
function void
gen_block(Ast_Block *block){
  gen("{");
  global_indent++;
  For(block->stmts) {
    gen_line(it);
    genln("");
    gen_ast(it);
  }
  global_indent--;
  genln("}");
}

enum {
  ALWAYS_EMIT_VALUE = 0,
  DONT_EMIT_VALUE = 1,
};

function void
gen_var(Intern_String name, Ast_Resolved_Type *type, Ast_Expr *expr, B32 emit_value){
  if(is_array(type)){
    gen("Slice %s", name.str);
  } else{
    gen_simple_decl(type, name);
  }

  if(emit_value == DONT_EMIT_VALUE){
    return;
  }

  if(expr){
    gen(" = ");
    gen_expr(expr);
  } else if(is_array(type)){
    gen(" = (Slice){%d, (", type->arr.size);
    gen_simple_decl(type, {});
    gen("){}");
    gen("}");
  } else { // Default zero
    if(is_numeric(type)){
      gen(" = 0");
    } else {
      gen(" = {}");
    }
  }
}

function void
gen_ast(Ast *ast){
  switch(ast->kind){

    CASE(PACKAGE, Package){
      if(emit_line_directives)
        genln("#line 0 \"%s\"", node->name.str);
      For(node->ordered) {
        gen_line(it);
        genln("");
        gen_ast(it);
      }
      BREAK();
    }

    CASE(RETURN, Return){
      gen("return");
      if(node->expr){
        gen(" ");
        gen_expr(node->expr);
      }
      gen(";");
      BREAK();
    }

    CASE(VAR, Var){
      Sym *sym = resolved_get(node);
      gen_var(sym->name, sym->type, node->expr, is_inside_struct ? DONT_EMIT_VALUE : ALWAYS_EMIT_VALUE);
      gen(";");
      BREAK();
    }

    CASE(IF, If){
      For(node->ifs){
        if(it->init) gen_expr(it->init);
        if(node->ifs.is_first(&it)){
          gen("if(");
          gen_expr(it->expr);
          gen(")");
          gen_block(it->block);
        }
        else{
          genln("else");
          if(it->expr){
            gen(" if(");
            gen_expr(it->expr);
            gen(")");
          }
          gen_block(it->block);
        }
      }
      BREAK();
    }

    CASE(PASS, Pass){
      unused(node);
      gen("//pass");
      BREAK();
    }

    CASE(BINARY,Binary){
      gen_expr(node);
      gen(";");
      BREAK();
    }

    CASE(FOR, For){
      gen("for(");
      if(node->init) gen_expr(node->init);
      gen(";");
      if(node->cond) gen_expr(node->cond);
      gen(";");
      if(node->iter) gen_expr(node->iter);
      gen(")");
      gen_block(node->block);
      BREAK();
    }

    CASE(CONST, Const){
      Sym *sym = resolved_get(node);

      switch(sym->type->kind){
        CASE_FLOAT:{
          gen("// F64 %s = ", node->name.str);
          gen_value(sym->value);
        } break;
        CASE_INT:{
          gen("// constant int %s = ", node->name.str);
          gen_value(sym->value);
        }break;
        CASE_STRING:{
          gen("// const String %s = ", node->name.str);
          gen_value(sym->value);
        }break;
        CASE_BOOL:{
          gen("// const Bool %s = ", node->name.str);
          gen_value(sym->value);
        }break;

        case TYPE_LAMBDA:{
          if(node->value->kind == AST_LAMBDA){
            if(is_flag_set(node->flags, AST_FOREIGN)){
              return;
            }
            Ast_Lambda *lambda = (Ast_Lambda *)node->value;
            Ast_Resolved_Type *ret = resolved_type_get(lambda->ret);
            gen_simple_decl(ret, node->name);
            gen("(");
            For(lambda->args){
              assert(it->kind == AST_LAMBDA_ARG);
              Ast_Resolved_Type *type = resolved_type_get(it->typespec);
              gen_var(it->name, type, 0, DONT_EMIT_VALUE);
              if(&it != (lambda->args.end() - 1)) gen(", ");
            }
            gen(")");

            if(lambda->block) {
              gen_block(lambda->block);
            }
            else gen(";");
          }
          else{
            gen_simple_decl(sym->type, node->name);
            gen(" = ");
            gen_expr((Ast_Expr *)node->value);
            gen(";");
          }
        }break;

        case TYPE_TYPE:{
          if(sym->type_val->kind == TYPE_STRUCT){
            Ast_Struct *agg = (Ast_Struct *)sym->type_val->ast;
            if(node->value->kind == AST_STRUCT){
              gen("typedef struct %s{", node->name.str);
              global_indent++;
              is_inside_struct++;
              For(agg->members){
                genln("");
                gen_ast(it);
              }

              For(agg->const_members){
                genln("");
                gen_ast(it);
              }
              is_inside_struct--;
              global_indent--;
              genln("}%s;", node->name.str);
            }
            else{
              // Type alias
            }
          }
          else if(sym->type_val->kind == TYPE_ENUM){
            Ast_Enum *enu = (Ast_Enum *)sym->type_val->ast;
            assert(enu->kind == AST_ENUM);
            if(node->value->kind == AST_ENUM){
              gen("/*enum %s{", node->name.str);
              // @todo add typespec
              global_indent++;
              For(enu->members){
                genln("%s", it->name.str);
                gen(" = ");
                Sym *value_sym = resolved_get(it);
                gen("%d", bigint_as_signed(&value_sym->big_int_val));
                gen(",");
              }
              global_indent--;
              genln("};*/");
            }
            else{
              // Type alias
            }
          }
          else{
            gen("// typedef ");
            gen_simple_decl(sym->type_val, node->name);
            gen(";");
          }
        }break;
        default: parsing_error(node->pos, "C_Codegen: Unhandled type %s of constant expression", docname(sym->type));
      }

      BREAK();
    }

    default: {
      assert(is_flag_set(ast->flags, AST_EXPR));
      gen_expr((Ast_Expr *)ast);
      gen(";");
    }
  }
}

function String
compile_string(String filecontent, String filename = "default_name"_s){
  F64 total_time = os_time();
  Scratch scratch(thread_ctx.scratch);
  OS_Heap heap = win32_os_heap_create(false, mib(4), 0);

  Parse_Ctx ctx = {};
  parse_init(&ctx, scratch, &heap);

  F64 tokenize_begin = os_time();
  lex_restream(&ctx, filecontent, filename);
  F64 tokenize_end = os_time();

  F64 parse_begin = os_time();
  Ast_Package *result = parse_file();
  sym_insert_builtins();
  pctx->resolving_package = result;
  F64 parse_end = os_time();

  gen(R"==(
#include <stdint.h>
#include <stdio.h>
#include <math.h>
typedef int8_t   S8;
typedef int16_t  S16;
typedef int32_t  S32;
typedef int64_t  S64;
typedef uint8_t  U8;
typedef uint16_t U16;
typedef uint32_t U32;
typedef uint64_t U64;
typedef S8       B8;
typedef S16      B16;
typedef S32      B32;
typedef S64      B64;
typedef U64      SizeU;
typedef S64      SizeS;
typedef float    F32;
typedef double   F64;
typedef S32     Bool;

typedef struct Slice{
  S64 len;
  void *data;
}Slice;

typedef struct String{
  U8 *str;
  S64 len;
}String;
#define LIT(x) (String){.str=(U8 *)x, .len=sizeof(x)-1}

void entry();
int main(){
  entry();
}
  )==");

  F64 resolve_begin = os_time();
  resolve_package(result);
  F64 resolve_end = os_time();

  F64 codegen_begin = os_time();
  gen_ast(result);
  F64 codegen_end = os_time();

  exp_destroy(&heap);

  F64 flattening_begin = os_time();
  String string_result = string_flatten(scratch, &pctx->gen);
  F64 flattening_end = os_time();

  printf("\n//-------------------------------");
  printf("\n// Tokenization: %f", tokenize_end - tokenize_begin);
  printf("\n// Parsing     : %f", parse_end    - parse_begin);
  printf("\n// Resolving   : %f", resolve_end  - resolve_begin);
  printf("\n// Codegen     : %f", codegen_end  - codegen_begin);
  printf("\n// Flattening  : %f", flattening_end - flattening_begin);
  printf("\n// Total       : %f", flattening_end - total_time);
  printf("\n//-------------------------------");

  return string_result;
}

function String
compile_file(String filename){
  Scratch scratch;
  String filecontent = os_read_file(scratch, filename);
  assert(filecontent.len);
  String result = compile_string(filecontent, filename);
  return result;
}

typedef struct Custom_Data{
  S32 thing;
}Custom_Data;


typedef struct Slice{
  S64 len;
  void *data;
}Slice;

Slice thing = (Slice){2, (Custom_Data []){(Custom_Data ){1}, (Custom_Data ){2}}};