// file      : build2/cxx/init.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2018 Code Synthesis Ltd
// license   : MIT; see accompanying LICENSE file

#include <build2/cxx/init.hxx>

#include <build2/scope.hxx>
#include <build2/context.hxx>
#include <build2/diagnostics.hxx>

#include <build2/cc/guess.hxx>
#include <build2/cc/module.hxx>

#include <build2/cxx/target.hxx>

using namespace std;
using namespace butl;

namespace build2
{
  namespace cxx
  {
    using cc::compiler_id;
    using cc::compiler_class;
    using cc::compiler_info;

    class config_module: public cc::config_module
    {
    public:
      explicit
      config_module (config_data&& d)
          : config_data (move (d)), cc::config_module (move (d)) {}

      virtual strings
      translate_std (const compiler_info&,
                     scope&,
                     const string*) const override;
    };

    using cc::module;

    strings config_module::
    translate_std (const compiler_info& ci, scope& rs, const string* v) const
    {
      strings r;

      compiler_id::value_type id (ci.id.value ());
      compiler_class cl (ci.class_);
      uint64_t mj (ci.version.major);
      uint64_t mi (ci.version.minor);
      uint64_t p (ci.version.patch);

      // Features.
      //
      auto enter = [&rs] (const char* v) -> const variable&
      {
        return var_pool.rw (rs).insert<bool> (v, variable_visibility::project);
      };

      // NOTE: see also module sidebuild subproject if changing anything about
      // modules here.

      //bool concepts (false); auto& v_c (enter ("cxx.features.concepts"));
      bool modules (false); auto& v_m (enter ("cxx.features.modules"));

      // Translate "latest" and "experimental" to the compiler/version-
      // appropriate option(s).
      //
      if (v != nullptr && (*v == "latest" || *v == "experimental"))
      {
        // Experimental is like latest with some extra stuff enabled via
        // additional switches.
        //
        const char* o (nullptr);

        switch (id)
        {
        case compiler_id::msvc:
          {
            // VC14u3 and later has /std:c++latest.
            //
            if (mj > 19 || (mj == 19 && (mi > 0 || (mi == 0 && p >= 24215))))
              o = "/std:c++latest";

            break;
          }
        case compiler_id::gcc:
          {
            if      (mj >= 8)            o = "-std=c++2a"; // 20
            else if (mj >= 5)            o = "-std=c++1z"; // 17
            else if (mj == 4 && mi >= 8) o = "-std=c++1y"; // 14
            else if (mj == 4 && mi >= 4) o = "-std=c++0x"; // 11

            break;
          }
        case compiler_id::clang:
        case compiler_id::clang_apple:
          {
            // Remap Apple versions to vanilla Clang based on the following
            // release point. Note that Apple no longer discloses the mapping
            // so it's a guesswork and we try to be conservative. For details
            // see:
            //
            // https://gist.github.com/yamaya/2924292
            //
            // 5.1 -> 3.4
            // 6.0 -> 3.5
            // 7.0 -> 3.7
            // 7.3 -> 3.8
            // 8.0 -> 3.9
            // 9.0 -> 4.0 (later ones could be 5.0)
            //
            // Note that this mapping is also used to enable experimental
            // features below.
            //
            if (id == compiler_id::clang_apple)
            {
              if      (mj >= 9)            {mj = 4; mi = 0;}
              else if (mj == 8)            {mj = 3; mi = 9;}
              else if (mj == 7 && mi >= 3) {mj = 3; mi = 8;}
              else if (mj == 7)            {mj = 3; mi = 7;}
              else if (mj == 6)            {mj = 3; mi = 5;}
              else if (mj == 5 && mi >= 1) {mj = 3; mi = 4;}
              else                         {mj = 3; mi = 0;}
            }

            if       (mj >= 5)                         o = "-std=c++2a"; // 20
            else if  (mj >  3 || (mj == 3 && mi >= 5)) o = "-std=c++1z"; // 17
            else if  (mj == 3 && mi >= 4)              o = "-std=c++1y"; // 14
            else     /* ??? */                         o = "-std=c++0x"; // 11

            break;
          }
        case compiler_id::icc:
          {
            if      (mj >= 17)                         o = "-std=c++1z"; // 17
            else if (mj >  15 || (mj == 15 && p >= 3)) o = "-std=c++1y"; // 14
            else    /* ??? */                          o = "-std=c++0x"; // 11

            break;
          }
        }

        if (o != nullptr)
          r.push_back (o);

        if (*v == "experimental")
        {
          // Unless disabled by the user, try to enable C++ modules. Here
          // we use a tri-state:
          //
          // - false        - disabled
          // - unspecified  - enabled if practically usable
          // - true         - enabled even if practically unusable
          //
          lookup l;
          if (!(l = rs[v_m]) || cast<bool> (l))
          {
            switch (id)
            {
            case compiler_id::msvc:
              {
                // While modules are supported in VC15u0 (19.10), there is a
                // bug in separate interface/implementation unit support which
                // makes them pretty much unusable. This has been fixed in
                // VC15u3 (19.11). And VC15u5 (19.12) supports the 'export
                // module M;' syntax.
                //
                if (mj > 19 || (mj == 19 && mi >= (l ? 10 : 12)))
                {
                  r.push_back (
                    mj > 19 || mi > 11
                    ? "/D__cpp_modules=201704"   // p0629r0 (export module M;)
                    : "/D__cpp_modules=201703"); // n4647   (       module M;)

                  r.push_back ("/experimental:module");
                  modules = true;
                }
                break;
              }
            case compiler_id::gcc:
              {
                // Enable starting with GCC 8.0.0 (currently the c++-modules
                // branch).
                //
                if (l && // Barely usable at the moment.
                    mj >= 8 &&
                    ci.version.build.find ("c++-modules") != string::npos)
                {
                  r.push_back ("-fmodules");
                  modules = true;
                }
                break;
              }
            case compiler_id::clang:
            case compiler_id::clang_apple:
              {
                // Enable starting with Clang 6.0.0.
                //
                // Note that we are using Apple to vanilla Clang version re-
                // map from above so may need to update things there as well.
                //
                // Also see Clang modules support hack in cc::compile.
                //
                if (mj >= 6)
                {
                  r.push_back ("-D__cpp_modules=201704"); // p0629r0
                  r.push_back ("-fmodules-ts");
                  modules = true;
                }
                break;
              }
            case compiler_id::icc:
              break; // No modules support yet.
            }
          }
        }
      }
      else
      {
        // Otherwise translate the standard value.
        //
        switch (cl)
        {
        case compiler_class::msvc:
          {
            // C++ standard-wise, with VC you got what you got up until 14u2.
            // Starting with 14u3 there is now the /std: switch which defaults
            // to c++14 but can be set to c++latest. And from 15u3 it can be
            // c++17.
            //
            // The question is also whether we should verify that the
            // requested standard is provided by this VC version. And if so,
            // from which version should we say VC supports 11, 14, and 17? We
            // should probably be as loose as possible here since the author
            // will always be able to tighten (but not loosen) this in the
            // buildfile (i.e., detect unsupported versions).
            //
            // For now we are not going to bother doing this for C++03.
            //
            if (v == nullptr)
              ;
            else if (*v != "98" && *v != "03")
            {
              bool sup (false);

              if      (*v == "11") // C++11 since VS2010/10.0.
              {
                sup = mj >= 16;
              }
              else if (*v == "14") // C++14 since VS2015/14.0.
              {
                sup = mj >= 19;
              }
              else if (*v == "17") // C++17 since VS2015/14.0u2.
              {
                // Note: the VC15 compiler version is 19.10.
                //
                sup = (mj > 19 ||
                       (mj == 19 && (mi > 0 || (mi == 0 && p >= 23918))));
              }

              if (!sup)
                fail << "C++" << *v << " is not supported by "
                     << ci.signature <<
                  info << "required by " << project (rs) << '@'
                     << rs.out_path ();

              if (mj > 19 || (mj == 19 && mi >= 11)) // 15u3
              {
                if      (*v == "14") r.push_back ("/std:c++14");
                else if (*v == "17") r.push_back ("/std:c++17");
              }
              else if (mj == 19 && (mi > 0 || (mi == 0 && p >= 24215))) // 14u3
              {
                if      (*v == "14") r.push_back ("/std:c++14");
                else if (*v == "17") r.push_back ("/std:c++latest");
              }
            }
            break;
          }
        case compiler_class::gcc:
          {
            // Translate 11 to 0x, 14 to 1y, 17 to 1z, and 20 to 2a for
            // compatibility with older versions of the compilers.
            //
            if (v == nullptr)
              ;
            else
            {
              string o ("-std=");

              if      (*v == "98") o += "c++98";
              else if (*v == "03") o += "c++03";
              else if (*v == "11") o += "c++0x";
              else if (*v == "14") o += "c++1y";
              else if (*v == "17") o += "c++1z";
              else if (*v == "20") o += "c++2a";
              else o += *v; // In case the user specifies e.g., 'gnu++17'.

              r.push_back (move (o));
            }
            break;
          }
        }
      }

      rs.assign (v_m) = modules;
      //rs.assign (v_c) = concepts;

      return r;
    }

    static const char* const hinters[] = {"c", nullptr};

    // See cc::module for details on guess_init vs config_init.
    //
    bool
    guess_init (scope& rs,
                scope& bs,
                const location& loc,
                unique_ptr<module_base>& mod,
                bool,
                bool,
                const variable_map& hints)
    {
      tracer trace ("cxx::guess_init");
      l5 ([&]{trace << "for " << bs.out_path ();});

      // We only support root loading (which means there can only be one).
      //
      if (&rs != &bs)
        fail (loc) << "cxx.guess module must be loaded in project root";

      // Load cc.core.vars so that we can cache all the cc.* variables.
      //
      if (!cast_false<bool> (rs["cc.core.vars.loaded"]))
        load_module (rs, rs, "cc.core.vars", loc);

      // Enter all the variables and initialize the module data.
      //
      auto& v (var_pool.rw (rs));

      cc::config_data d {
        cc::lang::cxx,

        "cxx",
        "c++",
        "g++",
        ".ii",

        hinters,

        // Note: some overridable, some not.
        //
        v.insert<path>    ("config.cxx",          true),
        v.insert<strings> ("config.cxx.poptions", true),
        v.insert<strings> ("config.cxx.coptions", true),
        v.insert<strings> ("config.cxx.loptions", true),
        v.insert<strings> ("config.cxx.libs",     true),

        v.insert<process_path> ("cxx.path"),
        v.insert<dir_paths>    ("cxx.sys_lib_dirs"),
        v.insert<dir_paths>    ("cxx.sys_inc_dirs"),

        v.insert<strings> ("cxx.poptions"),
        v.insert<strings> ("cxx.coptions"),
        v.insert<strings> ("cxx.loptions"),
        v.insert<strings> ("cxx.libs"),

        v["cc.poptions"],
        v["cc.coptions"],
        v["cc.loptions"],
        v["cc.libs"],

        v.insert<strings>      ("cxx.export.poptions"),
        v.insert<strings>      ("cxx.export.coptions"),
        v.insert<strings>      ("cxx.export.loptions"),
        v.insert<vector<name>> ("cxx.export.libs"),

        v["cc.export.poptions"],
        v["cc.export.coptions"],
        v["cc.export.loptions"],
        v["cc.export.libs"],

        v.insert<string> ("cxx.stdlib"),

        v["cc.runtime"],
        v["cc.stdlib"],

        v["cc.type"],
        v["cc.system"],
        v["cc.module_name"],
        v["cc.reprocess"],

        // Ability to indicate that source is already (partially)
        // preprocessed. Valid values are 'none' (not preprocessed),
        // 'includes' (no #include directives in source), 'modules' (as above
        // plus no module declaration depends on preprocessor, e.g., #ifdef,
        // etc), and 'all' (the source is fully preprocessed). Note that for
        // 'all' the source can still contain comments and line
        // continuations. Note also that for some compilers (e.g., VC) there
        // is no way to signal that the source is already preprocessed.
        //
        v.insert<string>   ("cxx.preprocessed"),

        nullptr, // cxx.features.symexport (set in init() below).

        v.insert<string>   ("cxx.std", variable_visibility::project),

        v.insert<string>   ("cxx.id"),
        v.insert<string>   ("cxx.id.type"),
        v.insert<string>   ("cxx.id.variant"),

        v.insert<string>   ("cxx.class"),

        v.insert<string>   ("cxx.version"),
        v.insert<uint64_t> ("cxx.version.major"),
        v.insert<uint64_t> ("cxx.version.minor"),
        v.insert<uint64_t> ("cxx.version.patch"),
        v.insert<string>   ("cxx.version.build"),

        v.insert<string>   ("cxx.signature"),
        v.insert<string>   ("cxx.checksum"),

        v.insert<string>   ("cxx.pattern"),

        v.insert<target_triplet> ("cxx.target"),

        v.insert<string>   ("cxx.target.cpu"),
        v.insert<string>   ("cxx.target.vendor"),
        v.insert<string>   ("cxx.target.system"),
        v.insert<string>   ("cxx.target.version"),
        v.insert<string>   ("cxx.target.class")
      };

      // Alias some cc. variables as cxx.
      //
      v.insert_alias (d.c_runtime, "cxx.runtime");
      v.insert_alias (d.c_module_name, "cxx.module_name");

      assert (mod == nullptr);
      config_module* m (new config_module (move (d)));
      mod.reset (m);
      m->guess (rs, loc, hints);
      return true;
    }

    bool
    config_init (scope& rs,
                 scope& bs,
                 const location& loc,
                 unique_ptr<module_base>&,
                 bool,
                 bool,
                 const variable_map& hints)
    {
      tracer trace ("cxx::config_init");
      l5 ([&]{trace << "for " << bs.out_path ();});

      // We only support root loading (which means there can only be one).
      //
      if (&rs != &bs)
        fail (loc) << "cxx.config module must be loaded in project root";

      // Load cxx.guess.
      //
      if (!cast_false<bool> (rs["cxx.guess.loaded"]))
        load_module (rs, rs, "cxx.guess", loc, false, hints);

      config_module& cm (*rs.modules.lookup<config_module> ("cxx.guess"));
      cm.init (rs, loc, hints);
      return true;
    }

    static const target_type* const hdr[] =
    {
      &hxx::static_type,
      &h::static_type,
      &ixx::static_type,
      &txx::static_type,
      &mxx::static_type,
      nullptr
    };

    static const target_type* const inc[] =
    {
      &hxx::static_type,
      &h::static_type,
      &ixx::static_type,
      &txx::static_type,
      &mxx::static_type,
      &cxx::static_type,
      &c::static_type,
      nullptr
    };

    bool
    init (scope& rs,
          scope& bs,
          const location& loc,
          unique_ptr<module_base>& mod,
          bool,
          bool,
          const variable_map& hints)
    {
      tracer trace ("cxx::init");
      l5 ([&]{trace << "for " << bs.out_path ();});

      // We only support root loading (which means there can only be one).
      //
      if (&rs != &bs)
        fail (loc) << "cxx module must be loaded in project root";

      // Load cxx.config.
      //
      if (!cast_false<bool> (rs["cxx.config.loaded"]))
        load_module (rs, rs, "cxx.config", loc, false, hints);

      config_module& cm (*rs.modules.lookup<config_module> ("cxx.guess"));

      auto& vp (var_pool.rw (rs));

      bool modules (cast<bool> (rs["cxx.features.modules"]));

      bool symexport (false);
      if (modules)
      {
        auto& var (vp.insert<bool> ("cxx.features.symexport",
                                    variable_visibility::project));
        symexport = cast_false<bool> (rs[var]);
        cm.x_symexport = &var;
      }

      cc::data d {
        cm,

        "cxx.compile",
        "cxx.link",
        "cxx.install",
        "cxx.uninstall",

        cm.ci_->id.value (),
        cm.ci_->class_,
        cm.ci_->version.major,
        cm.ci_->version.minor,
        cast<process_path>   (rs[cm.x_path]),
        cast<target_triplet> (rs[cm.x_target]),

        cm.tstd,

        modules,
        symexport,

        cast<dir_paths> (rs[cm.x_sys_lib_dirs]),
        cast<dir_paths> (rs[cm.x_sys_inc_dirs]),

        cm.sys_lib_dirs_extra,
        cm.sys_inc_dirs_extra,

        cxx::static_type,
        modules ? &mxx::static_type : nullptr,
        hdr,
        inc
      };

      assert (mod == nullptr);
      module* m;
      mod.reset (m = new module (move (d)));
      m->init (rs, loc, hints);
      return true;
    }
  }
}