// file      : libbuild2/functions-builtin.cxx -*- C++ -*-
// license   : MIT; see accompanying LICENSE file

#include <sstream>

#include <libbuild2/scope.hxx>
#include <libbuild2/function.hxx>
#include <libbuild2/variable.hxx>

using namespace std;

namespace build2
{
  // Note: not static since used by type-specific sort() implementations.
  //
  bool
  functions_sort_flags (optional<names> fs)
  {
    bool r (false);
    if (fs)
    {
      for (name& f: *fs)
      {
        string s (convert<string> (move (f)));

        if (s == "dedup")
          r = true;
        else
          throw invalid_argument ("invalid flag '" + s + "'");
      }
    }
    return r;
  };

  void
  builtin_functions (function_map& m)
  {
    function_family f (m, "builtin");

    // Note that we may want to extend the scope argument to a more general
    // notion of "lookup context" (scope, target, prerequisite).
    //
    // Note that this function is not pure.
    //
    f.insert ("defined", false) += [](const scope* s, names name)
    {
      if (s == nullptr)
        fail << "defined() called out of scope" << endf;

      return (*s)[convert<string> (move (name))].defined ();
    };

    // Return variable visibility if it has been entered and NULL otherwise.
    //
    // Note that this function is not pure.
    //
    f.insert ("visibility", false) += [](const scope* s, names name)
    {
      if (s == nullptr)
        fail << "visibility() called out of scope" << endf;

      const variable* var (
        s->ctx.var_pool.find (convert<string> (move (name))));

      return (var != nullptr
              ? optional<string> (to_string (var->visibility))
              : nullopt);
    };

    f["type"] += [](value* v) {return v->type != nullptr ? v->type->name : "";};
    f["null"] += [](value* v) {return v->null;};
    f["empty"] += [](value* v)  {return v->null || v->empty ();};

    f["identity"] += [](value* v) {return move (*v);};

    // string
    //
    f["string"] += [](bool b) {return b ? "true" : "false";};
    f["string"] += [](int64_t i) {return to_string (i);};
    f["string"] += [](uint64_t i) {return to_string (i);};

    // Quote a value returning its string representation. If escape is true,
    // then also escape (with a backslash) the quote characters being added
    // (this is useful if the result will be re-parsed, for example as a
    // Testscript command line).
    //
    f["quote"] += [](value* v, optional<value> escape)
    {
      if (v->null)
        return string ();

      untypify (*v); // Reverse to names.

      ostringstream os;
      to_stream (os,
                 v->as<names> (),
                 true /* quote */,
                 '@'  /* pair */,
                 escape && convert<bool> (move (*escape)));
      return os.str ();
    };

    // $size(<ints>)
    //
    // Return the number of elements in the sequence.
    //
    f["size"] += [] (int64s v) {return v.size ();};
    f["size"] += [] (uint64s v) {return v.size ();};

    // $sort(<ints> [, <flags>])
    //
    // Sort integers in ascending order.
    //
    // The following flags are supported:
    //
    //   dedup - in addition to sorting also remove duplicates
    //
    f["sort"] += [](int64s v, optional<names> fs)
    {
      sort (v.begin (), v.end ());

      if (functions_sort_flags (move (fs)))
        v.erase (unique (v.begin(), v.end()), v.end ());

      return v;
    };

    f["sort"] += [](uint64s v, optional<names> fs)
    {
      sort (v.begin (), v.end ());

      if (functions_sort_flags (move (fs)))
        v.erase (unique (v.begin(), v.end()), v.end ());

      return v;
    };

    // getenv
    //
    // Return NULL if the environment variable is not set, untyped value
    // otherwise.
    //
    // Note that if the build result can be affected by the variable being
    // queried, then it should be reported with the config.environment
    // directive.
    //
    // Note that this function is not pure.
    //
    f.insert ("getenv", false) += [](names name)
    {
      optional<string> v (getenv (convert<string> (move (name))));

      if (!v)
        return value ();

      names r;
      r.emplace_back (to_name (move (*v)));
      return value (move (r));
    };
  }
}