#include "tysolver.h"
#include "lib/tysy.h"

void tysolver_init(tysolver_t* tysolver, sym_t* sym, tysy_t* tysy)
{
  assert(tysolver);
  assert(sym);
  assert(tysy);

  tysolver->sym = sym;
  tysolver->tysy = tysy;
  tysolver->scope = 0;
}

void tysolver_free(tysolver_t* tysolver)
{
  assert(tysolver);
}

/*
  #define NODE_TYPE(G)                                            \
  G(NODE_MOD),                                                  \
    G(NODE_LET), G(NODE_IDENT), G(NODE_ASSIGN), G(NODE_VARDECL)
 */
type_t* tysolver_try_solve_node(tysolver_t* tysolver, node_t* node)
{
  assert(tysolver);
  assert(node);

  switch (node->type)
    {
    case NODE_BLOCK: {
      tysolver->scope++;

      if (node->children.size > 0)
        {
          size_t last = node->children.size - 1;

          return tysolver_try_solve_node(tysolver,
                                         (node_t*) node->children.data[last]);
        }
      tysolver->scope--;
    } break;

    case NODE_VARDECL: {
      return tysolver_try_solve_node(tysolver,
                                     (node_t*) node->children.data[1]);
    } break;

    case NODE_IDENT: {
      char* name = node->value.data;
      node_t* block = node_try_find_parent(node, NODE_BLOCK);
      sym_entry_t* entry = sym_try_find_by_name(tysolver->sym,
                                                name,
                                                tysolver->scope,
                                                SYM_PRE | SYM_DECL,
                                                block);
      assert(entry);

      return entry->type;
    } break;

    case NODE_SUB:
    case NODE_DIV:
    case NODE_MODULO:
    case NODE_POW:
    case NODE_NUM: {
      type_t* ty = tysy_try_find_type(tysolver->tysy, "num");
      assert(ty);
      return ty;
    } break;

    case NODE_ADD: {
      return tysolver_try_solve_node(tysolver,
                                     (node_t*) node->children.data[0]);
    } break;

    case NODE_MUL: {
      type_t* lhs = tysolver_try_solve_node(tysolver,
                                            (node_t*) node->children.data[0]);

      type_t* rhs = tysolver_try_solve_node(tysolver,
                                            (node_t*) node->children.data[1]);

      if (type_eq(lhs, rhs) && lhs->kind == TYPE_NUM)
        {
          return tysolver_try_solve_node(tysolver,
                                         (node_t*) node->children.data[0]);
        }
      else if ((lhs->kind == TYPE_NUM && rhs->kind == TYPE_STR)
               || (rhs->kind == TYPE_NUM && lhs->kind == TYPE_STR))
        {
          return tysy_try_find_type(tysolver->tysy, "str");
        }
      else
        {
          tysolver_error(tysolver, node);
        }

    } break;

    case NODE_ASSERT:
    case NODE_EQ:
    case NODE_NE:
    case NODE_LT:
    case NODE_LE:
    case NODE_GT:
    case NODE_GE:
    case NODE_AND:
    case NODE_OR:
    case NODE_NOT:
    case NODE_BOOL: {
      type_t* ty = tysy_try_find_type(tysolver->tysy, "bool");
      assert(ty);
      return ty;
    } break;

    case NODE_STR: {
      type_t* ty = tysy_try_find_type(tysolver->tysy, "str");
      assert(ty);
      return ty;
    } break;

    default: {
      tysolver_error(tysolver, node);
    } break;
    }

  return NULL;
}

void tysolver_error(tysolver_t* tysolver, node_t* node)
{
  fprintf(stderr, "Cannot solve type of '%s'.\n",
          NodeTypeStr[node->type]);
  abort();
}