#include "sass.hpp"

#include <vector>

#include "check_nesting.hpp"

namespace Sass {

  CheckNesting::CheckNesting()

  : parents(std::vector<Statement_Ptr>()),

    parent(0),

    current_mixin_definition(0)

  { }

  Statement_Ptr CheckNesting::visit_children(Statement_Ptr parent)

  {

    Statement_Ptr old_parent = this->parent;

    if (At_Root_Block_Ptr root = Cast<At_Root_Block>(parent)) {

      std::vector<Statement_Ptr> old_parents = this->parents;

      std::vector<Statement_Ptr> new_parents;

      for (size_t i = 0, L = this->parents.size(); i < L; i++) {

        Statement_Ptr p = this->parents.at(i);

        if (!root->exclude_node(p)) {

          new_parents.push_back(p);

        }

      }

      this->parents = new_parents;

      for (size_t i = this->parents.size(); i > 0; i--) {

        Statement_Ptr p = 0;

        Statement_Ptr gp = 0;

        if (i > 0) p = this->parents.at(i - 1);

        if (i > 1) gp = this->parents.at(i - 2);

        if (!this->is_transparent_parent(p, gp)) {

          this->parent = p;

          break;

        }

      }

      At_Root_Block_Ptr ar = Cast<At_Root_Block>(parent);

      Statement_Ptr ret = this->visit_children(ar->block());

      this->parent = old_parent;

      this->parents = old_parents;

      return ret;

    }

    if (!this->is_transparent_parent(parent, old_parent)) {

      this->parent = parent;

    }

    this->parents.push_back(parent);

    Block_Ptr b = Cast<Block>(parent);

    if (!b) {

      if (Has_Block_Ptr bb = Cast<Has_Block>(parent)) {

        b = bb->block();

      }

    }

    if (b) {

      for (auto n : b->elements()) {

        n->perform(this);

      }

    }

    this->parent = old_parent;

    this->parents.pop_back();

    return b;

  }

  Statement_Ptr CheckNesting::operator()(Block_Ptr b)

  {

    return this->visit_children(b);

  }

  Statement_Ptr CheckNesting::operator()(Definition_Ptr n)

  {

    if (!this->should_visit(n)) return NULL;

    if (!is_mixin(n)) {

      visit_children(n);

      return n;

    }

    Definition_Ptr old_mixin_definition = this->current_mixin_definition;

    this->current_mixin_definition = n;

    visit_children(n);

    this->current_mixin_definition = old_mixin_definition;

    return n;

  }

  Statement_Ptr CheckNesting::fallback_impl(Statement_Ptr s)

  {

    Block_Ptr b1 = Cast<Block>(s);

    Has_Block_Ptr b2 = Cast<Has_Block>(s);

    return b1 || b2 ? visit_children(s) : s;

  }

  bool CheckNesting::should_visit(Statement_Ptr node)

  {

    if (!this->parent) return true;

    if (Cast<Content>(node))

    { this->invalid_content_parent(this->parent); }

    if (is_charset(node))

    { this->invalid_charset_parent(this->parent); }

    if (Cast<Extension>(node))

    { this->invalid_extend_parent(this->parent); }

    // if (Cast<Import>(node))

    // { this->invalid_import_parent(this->parent); }

    if (this->is_mixin(node))

    { this->invalid_mixin_definition_parent(this->parent); }

    if (this->is_function(node))

    { this->invalid_function_parent(this->parent); }

    if (this->is_function(this->parent))

    { this->invalid_function_child(node); }

    if (Cast<Declaration>(node))

    { this->invalid_prop_parent(this->parent); }

    if (Cast<Declaration>(this->parent))

    { this->invalid_prop_child(node); }

    if (Cast<Return>(node))

    { this->invalid_return_parent(this->parent); }

    return true;

  }

  void CheckNesting::invalid_content_parent(Statement_Ptr parent)

  {

    if (!this->current_mixin_definition) {

      throw Exception::InvalidSass(

        parent->pstate(),

        "@content may only be used within a mixin."

      );

    }

  }

  void CheckNesting::invalid_charset_parent(Statement_Ptr parent)

  {

    if (!(

        is_root_node(parent)

    )) {

      throw Exception::InvalidSass(

        parent->pstate(),

        "@charset may only be used at the root of a document."

      );

    }

  }

  void CheckNesting::invalid_extend_parent(Statement_Ptr parent)

  {

    if (!(

        Cast<Ruleset>(parent) ||

        Cast<Mixin_Call>(parent) ||

        is_mixin(parent)

    )) {

      throw Exception::InvalidSass(

        parent->pstate(),

        "Extend directives may only be used within rules."

      );

    }

  }

  // void CheckNesting::invalid_import_parent(Statement_Ptr parent)

  // {

  //   for (auto pp : this->parents) {

  //     if (

  //         Cast<Each>(pp) ||

  //         Cast<For>(pp) ||

  //         Cast<If>(pp) ||

  //         Cast<While>(pp) ||

  //         Cast<Trace>(pp) ||

  //         Cast<Mixin_Call>(pp) ||

  //         is_mixin(pp)

  //     ) {

  //       throw Exception::InvalidSass(

  //         parent->pstate(),

  //         "Import directives may not be defined within control directives or other mixins."

  //       );

  //     }

  //   }

  //   if (this->is_root_node(parent)) {

  //     return;

  //   }

  //   if (false/*n.css_import?*/) {

  //     throw Exception::InvalidSass(

  //       parent->pstate(),

  //       "CSS import directives may only be used at the root of a document."

  //     );

  //   }

  // }

  void CheckNesting::invalid_mixin_definition_parent(Statement_Ptr parent)

  {

    for (Statement_Ptr pp : this->parents) {

      if (

          Cast<Each>(pp) ||

          Cast<For>(pp) ||

          Cast<If>(pp) ||

          Cast<While>(pp) ||

          Cast<Trace>(pp) ||

          Cast<Mixin_Call>(pp) ||

          is_mixin(pp)

      ) {

        throw Exception::InvalidSass(

          parent->pstate(),

          "Mixins may not be defined within control directives or other mixins."

        );

      }

    }

  }

  void CheckNesting::invalid_function_parent(Statement_Ptr parent)

  {

    for (Statement_Ptr pp : this->parents) {

      if (

          Cast<Each>(pp) ||

          Cast<For>(pp) ||

          Cast<If>(pp) ||

          Cast<While>(pp) ||

          Cast<Trace>(pp) ||

          Cast<Mixin_Call>(pp) ||

          is_mixin(pp)

      ) {

        throw Exception::InvalidSass(

          parent->pstate(),

          "Functions may not be defined within control directives or other mixins."

        );

      }

    }

  }

  void CheckNesting::invalid_function_child(Statement_Ptr child)

  {

    if (!(

        Cast<Each>(child) ||

        Cast<For>(child) ||

        Cast<If>(child) ||

        Cast<While>(child) ||

        Cast<Trace>(child) ||

        Cast<Comment>(child) ||

        Cast<Debug>(child) ||

        Cast<Return>(child) ||

        Cast<Variable>(child) ||

        // Ruby Sass doesn't distinguish variables and assignments

        Cast<Assignment>(child) ||

        Cast<Warning>(child) ||

        Cast<Error>(child)

    )) {

      throw Exception::InvalidSass(

        child->pstate(),

        "Functions can only contain variable declarations and control directives."

      );

    }

  }

  void CheckNesting::invalid_prop_child(Statement_Ptr child)

  {

    if (!(

        Cast<Each>(child) ||

        Cast<For>(child) ||

        Cast<If>(child) ||

        Cast<While>(child) ||

        Cast<Trace>(child) ||

        Cast<Comment>(child) ||

        Cast<Declaration>(child) ||

        Cast<Mixin_Call>(child)

    )) {

      throw Exception::InvalidSass(

        child->pstate(),

        "Illegal nesting: Only properties may be nested beneath properties."

      );

    }

  }

  void CheckNesting::invalid_prop_parent(Statement_Ptr parent)

  {

    if (!(

        is_mixin(parent) ||

        is_directive_node(parent) ||

        Cast<Ruleset>(parent) ||

        Cast<Keyframe_Rule>(parent) ||

        Cast<Declaration>(parent) ||

        Cast<Mixin_Call>(parent)

    )) {

      throw Exception::InvalidSass(

        parent->pstate(),

        "Properties are only allowed within rules, directives, mixin includes, or other properties."

      );

    }

  }

  void CheckNesting::invalid_return_parent(Statement_Ptr parent)

  {

    if (!this->is_function(parent)) {

      throw Exception::InvalidSass(

        parent->pstate(),

        "@return may only be used within a function."

      );

    }

  }

  bool CheckNesting::is_transparent_parent(Statement_Ptr parent, Statement_Ptr grandparent)

  {

    bool parent_bubbles = parent && parent->bubbles();

    bool valid_bubble_node = parent_bubbles &&

                             !is_root_node(grandparent) &&

                             !is_at_root_node(grandparent);

    return Cast<Import>(parent) ||

           Cast<Each>(parent) ||

           Cast<For>(parent) ||

           Cast<If>(parent) ||

           Cast<While>(parent) ||

           Cast<Trace>(parent) ||

           valid_bubble_node;

  }

  bool CheckNesting::is_charset(Statement_Ptr n)

  {

    Directive_Ptr d = Cast<Directive>(n);

    return d && d->keyword() == "charset";

  }

  bool CheckNesting::is_mixin(Statement_Ptr n)

  {

    Definition_Ptr def = Cast<Definition>(n);

    return def && def->type() == Definition::MIXIN;

  }

  bool CheckNesting::is_function(Statement_Ptr n)

  {

    Definition_Ptr def = Cast<Definition>(n);

    return def && def->type() == Definition::FUNCTION;

  }

  bool CheckNesting::is_root_node(Statement_Ptr n)

  {

    if (Cast<Ruleset>(n)) return false;

    Block_Ptr b = Cast<Block>(n);

    return b && b->is_root();

  }

  bool CheckNesting::is_at_root_node(Statement_Ptr n)

  {

    return Cast<At_Root_Block>(n) != NULL;

  }

  bool CheckNesting::is_directive_node(Statement_Ptr n)

  {

    return Cast<Directive>(n) ||

           Cast<Import>(n) ||

           Cast<Media_Block>(n) ||

           Cast<Supports_Block>(n);

  }

}