#include <iostream>
#include <typeinfo>

#include "expand.hpp"
#include "bind.hpp"
#include "eval.hpp"
#include "contextualize.hpp"
#include "to_string.hpp"
#include "backtrace.hpp"
#include "context.hpp"
#include "parser.hpp"

namespace Sass {

  Expand::Expand(Context& ctx, Eval* eval, Contextualize* contextualize, Env* env, Backtrace* bt)
  : ctx(ctx),
    eval(eval),
    contextualize(contextualize),
    env(env),
    block_stack(vector<Block*>()),
    property_stack(vector<String*>()),
    selector_stack(vector<Selector*>()),
    at_root_selector_stack(vector<Selector*>()),
    in_at_root(false),
    in_keyframes(false),
    backtrace(bt)
  { selector_stack.push_back(0); }

  Statement* Expand::operator()(Block* b)
  {
    Env new_env;
    new_env.link(*env);
    env = &new_env;
    Block* bb = new (ctx.mem) Block(b->pstate(), b->length(), b->is_root());
    block_stack.push_back(bb);
    append_block(b);
    block_stack.pop_back();
    env = env->parent();
    return bb;
  }

  Statement* Expand::operator()(Ruleset* r)
  {
    bool old_in_at_root = in_at_root;
    in_at_root = false;

    if (in_keyframes) {
      To_String to_string;
      Keyframe_Rule* k = new (ctx.mem) Keyframe_Rule(r->pstate(), r->block()->perform(this)->block());
      if (r->selector()) {
        string s(r->selector()->perform(eval->with(env, backtrace))->perform(&to_string));
        String_Constant* ss = new (ctx.mem) String_Constant(r->selector()->pstate(), s);
        k->rules(ss);
      }
      in_at_root = old_in_at_root;
      old_in_at_root = false;
      return k;
    }

    Contextualize* contextual = contextualize->with(selector_stack.back(), env, backtrace);
    if (old_in_at_root && !r->selector()->has_reference())
      contextual = contextualize->with(at_root_selector_stack.back(), env, backtrace);

    Selector* sel_ctx = r->selector()->perform(contextual);
    if (sel_ctx == 0) throw "Cannot expand null selector";

    Emitter emitter(&ctx);
    Inspect isp(emitter);
    sel_ctx->perform(&isp);
    string str = isp.get_buffer();
    str += ";";

    Parser p(ctx, ParserState("[REPARSE]", 0));
    p.source   = str.c_str();
    p.position = str.c_str();
    p.end      = str.c_str() + strlen(str.c_str());
    Selector_List* sel_lst = p.parse_selector_group();
    sel_lst->pstate(isp.remap(sel_lst->pstate()));

    for(size_t i = 0; i < sel_lst->length(); i++) {

      Complex_Selector* pIter = (*sel_lst)[i];
      while (pIter) {
        Compound_Selector* pHead = pIter->head();
        pIter->pstate(isp.remap(pIter->pstate()));
        if (pHead) {
          pHead->pstate(isp.remap(pHead->pstate()));
          (*pHead)[0]->pstate(isp.remap((*pHead)[0]->pstate()));
        }
        pIter = pIter->tail();
      }
    }
    sel_ctx = sel_lst;

    selector_stack.push_back(sel_ctx);
    Block* blk = r->block()->perform(this)->block();
    Ruleset* rr = new (ctx.mem) Ruleset(r->pstate(),
                                        sel_ctx,
                                        blk);
    rr->tabs(r->tabs());
    selector_stack.pop_back();
    in_at_root = old_in_at_root;
    old_in_at_root = false;
    return rr;
  }

  Statement* Expand::operator()(Propset* p)
  {
    property_stack.push_back(p->property_fragment());
    Block* expanded_block = p->block()->perform(this)->block();

    Block* current_block = block_stack.back();
    for (size_t i = 0, L = expanded_block->length(); i < L; ++i) {
      Statement* stm = (*expanded_block)[i];
      if (typeid(*stm) == typeid(Declaration)) {
        Declaration* dec = static_cast<Declaration*>(stm);
        String_Schema* combined_prop = new (ctx.mem) String_Schema(p->pstate());
        if (!property_stack.empty()) {
          *combined_prop << property_stack.back()
                         << new (ctx.mem) String_Constant(p->pstate(), "-")
                         << dec->property(); // TODO: eval the prop into a string constant
        }
        else {
          *combined_prop << dec->property();
        }
        dec->property(combined_prop);
        *current_block << dec;
      }
      else if (typeid(*stm) == typeid(Comment)) {
        // drop comments in propsets
      }
      else {
        error("contents of namespaced properties must result in style declarations only", stm->pstate(), backtrace);
      }
    }

    property_stack.pop_back();

    return 0;
  }

  Statement* Expand::operator()(Feature_Block* f)
  {
    Expression* feature_queries = f->feature_queries()->perform(eval->with(env, backtrace));
    Feature_Block* ff = new (ctx.mem) Feature_Block(f->pstate(),
                                                    static_cast<Feature_Query*>(feature_queries),
                                                    f->block()->perform(this)->block());
    ff->selector(selector_stack.back());
    return ff;
  }

  Statement* Expand::operator()(Media_Block* m)
  {
    To_String to_string(&ctx);
    Expression* mq = m->media_queries()->perform(eval->with(env, backtrace));
    mq = Parser::from_c_str(mq->perform(&to_string).c_str(), ctx, mq->pstate()).parse_media_queries();
    Media_Block* mm = new (ctx.mem) Media_Block(m->pstate(),
                                                static_cast<List*>(mq),
                                                m->block()->perform(this)->block(),
                                                selector_stack.back());
    mm->tabs(m->tabs());
    return mm;
  }

  Statement* Expand::operator()(At_Root_Block* a)
  {
    in_at_root = true;
    at_root_selector_stack.push_back(0);
    Block* ab = a->block();
    Expression* ae = a->expression();
    if (ae) ae = ae->perform(eval->with(env, backtrace));
    else ae = new (ctx.mem) At_Root_Expression(a->pstate());
    Block* bb = ab ? ab->perform(this)->block() : 0;
    At_Root_Block* aa = new (ctx.mem) At_Root_Block(a->pstate(),
                                                    bb,
                                                    static_cast<At_Root_Expression*>(ae));
    at_root_selector_stack.pop_back();
    in_at_root = false;
    return aa;
  }

  Statement* Expand::operator()(At_Rule* a)
  {
    bool old_in_keyframes = in_keyframes;
    in_keyframes = a->is_keyframes();
    Block* ab = a->block();
    Selector* as = a->selector();
    Expression* av = a->value();
    if (as) as = as->perform(contextualize->with(0, env, backtrace));
    else if (av) av = av->perform(eval->with(env, backtrace));
    Block* bb = ab ? ab->perform(this)->block() : 0;
    At_Rule* aa = new (ctx.mem) At_Rule(a->pstate(),
                                        a->keyword(),
                                        as,
                                        bb);
    if (av) aa->value(av);
    in_keyframes = old_in_keyframes;
    return aa;
  }

  Statement* Expand::operator()(Declaration* d)
  {
    String* old_p = d->property();
    String* new_p = static_cast<String*>(old_p->perform(eval->with(env, backtrace)));
    Expression* value = d->value()->perform(eval->with(env, backtrace));

    if (value->is_invisible() && !d->is_important()) return 0;

    Declaration* decl = new (ctx.mem) Declaration(d->pstate(),
                                                  new_p,
                                                  value,
                                                  d->is_important());
    decl->tabs(d->tabs());
    return decl;
  }

  Statement* Expand::operator()(Assignment* a)
  {
    string var(a->variable());
    if (env->has(var)) {
      Expression* v = static_cast<Expression*>((*env)[var]);
      if (!a->is_guarded() || v->concrete_type() == Expression::NULL_VAL) (*env)[var] = a->value()->perform(eval->with(env, backtrace));
    }
    else {
      env->current_frame()[var] = a->value()->perform(eval->with(env, backtrace));
    }
    return 0;
  }

  Statement* Expand::operator()(Import* imp)
  {
    Import* result = new (ctx.mem) Import(imp->pstate());
    for ( size_t i = 0, S = imp->urls().size(); i < S; ++i) {
      result->urls().push_back(imp->urls()[i]->perform(eval->with(env, backtrace)));
    }
    return result;
  }

  Statement* Expand::operator()(Import_Stub* i)
  {
    append_block(ctx.style_sheets[i->file_name()]);
    return 0;
  }

  Statement* Expand::operator()(Warning* w)
  {
    // eval handles this too, because warnings may occur in functions
    w->perform(eval->with(env, backtrace));
    return 0;
  }

  Statement* Expand::operator()(Error* e)
  {
    // eval handles this too, because errors may occur in functions
    e->perform(eval->with(env, backtrace));
    return 0;
  }

  Statement* Expand::operator()(Debug* d)
  {
    // eval handles this too, because warnings may occur in functions
    d->perform(eval->with(env, backtrace));
    return 0;
  }

  Statement* Expand::operator()(Comment* c)
  {
    // TODO: eval the text, once we're parsing/storing it as a String_Schema
    return new (ctx.mem) Comment(c->pstate(), static_cast<String*>(c->text()->perform(eval->with(env, backtrace))), c->is_important());
  }

  Statement* Expand::operator()(If* i)
  {
    if (*i->predicate()->perform(eval->with(env, backtrace))) {
      append_block(i->consequent());
    }
    else {
      Block* alt = i->alternative();
      if (alt) append_block(alt);
    }
    return 0;
  }

  Statement* Expand::operator()(For* f)
  {
    string variable(f->variable());
    Expression* low = f->lower_bound()->perform(eval->with(env, backtrace));
    if (low->concrete_type() != Expression::NUMBER) {
      error("lower bound of `@for` directive must be numeric", low->pstate(), backtrace);
    }
    Expression* high = f->upper_bound()->perform(eval->with(env, backtrace));
    if (high->concrete_type() != Expression::NUMBER) {
      error("upper bound of `@for` directive must be numeric", high->pstate(), backtrace);
    }
    double start = static_cast<Number*>(low)->value();
    double end = static_cast<Number*>(high)->value();
    Env new_env;
    new_env[variable] = new (ctx.mem) Number(low->pstate(), start);
    new_env.link(env);
    env = &new_env;
    Block* body = f->block();
    if (start < end) {
      if (f->is_inclusive()) ++end;
      for (double i = start;
           i < end;
           (*env)[variable] = new (ctx.mem) Number(low->pstate(), ++i)) {
        append_block(body);
      }
    } else {
      if (f->is_inclusive()) --end;
      for (double i = start;
           i > end;
           (*env)[variable] = new (ctx.mem) Number(low->pstate(), --i)) {
        append_block(body);
      }
    }
    env = new_env.parent();
    return 0;
  }

  Statement* Expand::operator()(Each* e)
  {
    vector<string> variables(e->variables());
    Expression* expr = e->list()->perform(eval->with(env, backtrace));
    List* list = 0;
    Map* map = 0;
    if (expr->concrete_type() == Expression::MAP) {
      map = static_cast<Map*>(expr);
    }
    else if (expr->concrete_type() != Expression::LIST) {
      list = new (ctx.mem) List(expr->pstate(), 1, List::COMMA);
      *list << expr;
    }
    else {
      list = static_cast<List*>(expr);
    }
    Env new_env;
    for (size_t i = 0, L = variables.size(); i < L; ++i) new_env[variables[i]] = 0;
    new_env.link(env);
    env = &new_env;
    Block* body = e->block();

    if (map) {
      for (auto key : map->keys()) {
        Expression* k = key->perform(eval->with(env, backtrace));
        Expression* v = map->at(key)->perform(eval->with(env, backtrace));

        if (variables.size() == 1) {
          List* variable = new (ctx.mem) List(map->pstate(), 2, List::SPACE);
          *variable << k;
          *variable << v;
          (*env)[variables[0]] = variable;
        } else {
          (*env)[variables[0]] = k;
          (*env)[variables[1]] = v;
        }
        append_block(body);
      }
    }
    else {
      for (size_t i = 0, L = list->length(); i < L; ++i) {
        List* variable = 0;
        if ((*list)[i]->concrete_type() != Expression::LIST  || variables.size() == 1) {
          variable = new (ctx.mem) List((*list)[i]->pstate(), 1, List::COMMA);
          *variable << (*list)[i];
        }
        else {
          variable = static_cast<List*>((*list)[i]);
        }
        for (size_t j = 0, K = variables.size(); j < K; ++j) {
          if (j < variable->length()) {
            (*env)[variables[j]] = (*variable)[j]->perform(eval->with(env, backtrace));
          }
          else {
            (*env)[variables[j]] = new (ctx.mem) Null(expr->pstate());
          }
        }
        append_block(body);
      }
    }
    env = new_env.parent();
    return 0;
  }

  Statement* Expand::operator()(While* w)
  {
    Expression* pred = w->predicate();
    Block* body = w->block();
    while (*pred->perform(eval->with(env, backtrace))) {
      append_block(body);
    }
    return 0;
  }

  Statement* Expand::operator()(Return* r)
  {
    error("@return may only be used within a function", r->pstate(), backtrace);
    return 0;
  }

  Statement* Expand::operator()(Extension* e)
  {
    To_String to_string(&ctx);
    Selector_List* extender = static_cast<Selector_List*>(selector_stack.back());
    if (!extender) return 0;
    Selector_List* extendee = static_cast<Selector_List*>(e->selector()->perform(contextualize->with(0, env, backtrace)));
    if (extendee->length() != 1) {
      error("selector groups may not be extended", extendee->pstate(), backtrace);
    }
    Complex_Selector* c = (*extendee)[0];
    if (!c->head() || c->tail()) {
      error("nested selectors may not be extended", c->pstate(), backtrace);
    }
    Compound_Selector* s = c->head();

    // // need to convert the compound selector into a by-value data structure
    // vector<string> target_vec;
    // for (size_t i = 0, L = s->length(); i < L; ++i)
    // { target_vec.push_back((*s)[i]->perform(&to_string)); }

    for (size_t i = 0, L = extender->length(); i < L; ++i) {
      // let's test this out
      // cerr << "REGISTERING EXTENSION REQUEST: " << (*extender)[i]->perform(&to_string) << " <- " << s->perform(&to_string) << endl;
      ctx.subset_map.put(s->to_str_vec(), make_pair((*extender)[i], s));
    }
    return 0;
  }

  Statement* Expand::operator()(Definition* d)
  {
    Definition* dd = new (ctx.mem) Definition(*d);
    env->current_frame()[d->name() +
                        (d->type() == Definition::MIXIN ? "[m]" : "[f]")] = dd;
    // set the static link so we can have lexical scoping
    dd->environment(env);
    return 0;
  }

  Statement* Expand::operator()(Mixin_Call* c)
  {
    string full_name(c->name() + "[m]");
    if (!env->has(full_name)) {
      error("no mixin named " + c->name(), c->pstate(), backtrace);
    }
    Definition* def = static_cast<Definition*>((*env)[full_name]);
    Block* body = def->block();
    Parameters* params = def->parameters();
    Arguments* args = static_cast<Arguments*>(c->arguments()
                                               ->perform(eval->with(env, backtrace)));
    Backtrace here(backtrace, c->pstate(), ", in mixin `" + c->name() + "`");
    backtrace = &here;
    Env new_env;
    new_env.link(def->environment());
    if (c->block()) {
      // represent mixin content blocks as thunks/closures
      Definition* thunk = new (ctx.mem) Definition(c->pstate(),
                                                   "@content",
                                                   new (ctx.mem) Parameters(c->pstate()),
                                                   c->block(),
                                                   Definition::MIXIN);
      thunk->environment(env);
      new_env.current_frame()["@content[m]"] = thunk;
    }
    bind("mixin " + c->name(), params, args, ctx, &new_env, eval);
    Env* old_env = env;
    env = &new_env;
    append_block(body);
    env = old_env;
    backtrace = here.parent;
    return 0;
  }

  Statement* Expand::operator()(Content* c)
  {
    // convert @content directives into mixin calls to the underlying thunk
    if (!env->has("@content[m]")) return 0;
    Mixin_Call* call = new (ctx.mem) Mixin_Call(c->pstate(),
                                                "@content",
                                                new (ctx.mem) Arguments(c->pstate()));
    return call->perform(this);
  }

  inline Statement* Expand::fallback_impl(AST_Node* n)
  {
    error("unknown internal error; please contact the LibSass maintainers", n->pstate(), backtrace);
    String_Constant* msg = new (ctx.mem) String_Constant(ParserState("[WARN]"), string("`Expand` doesn't handle ") + typeid(*n).name());
    return new (ctx.mem) Warning(ParserState("[WARN]"), msg);
  }

  inline void Expand::append_block(Block* b)
  {
    Block* current_block = block_stack.back();
    for (size_t i = 0, L = b->length(); i < L; ++i) {
      Statement* ith = (*b)[i]->perform(this);
      if (ith) *current_block << ith;
    }
  }
}
