// file      : build2/config/init.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
// license   : MIT; see accompanying LICENSE file

#include <build2/config/init>

#include <build2/file>
#include <build2/rule>
#include <build2/scope>
#include <build2/context>
#include <build2/filesystem>  // exists()
#include <build2/diagnostics>

#include <build2/config/module>
#include <build2/config/utility>
#include <build2/config/operation>

using namespace std;
using namespace butl;

namespace build2
{
  namespace config
  {
    const string module::name ("config");
    const uint64_t module::version (1);

    void
    boot (scope& rs, const location& loc, unique_ptr<module_base>&)
    {
      tracer trace ("config::boot");

      const dir_path& out_root (rs.out_path ());
      l5 ([&]{trace << "for " << out_root;});

      // Register meta-operations.
      //
      rs.meta_operations.insert (configure_id, configure);
      rs.meta_operations.insert (disfigure_id, disfigure);

      // Load config.build if one exists.
      //
      // Note that we have to do this during bootstrap since the order in
      // which the modules will be initialized is unspecified. So it is
      // possible that some module which needs the configuration will get
      // called first.
      //
      const variable& c_v (var_pool.insert<uint64_t> ("config.version"));

      // Don't load it if we are disfiguring. This is a bit tricky since the
      // build2 core may not yet know it is disfiguring. But we know.
      //
      if (*current_mname != disfigure.name &&
          (!current_mname->empty () || *current_oname != disfigure.name))
      {
        path f (out_root / config_file);

        if (exists (f))
        {
          // Check the config version. We assume that old versions cannot
          // understand new configs and new versions are incompatible with old
          // configs.
          //
          // We extract the value manually instead of loading and then
          // checking in order to be able to fixup/migrate the file which we
          // may want to do in the future.
          //
          {
            // Assume missing version is 0.
            //
            auto p (extract_variable (f, c_v.name.c_str ()));
            uint64_t v (p.second ? cast<uint64_t> (p.first) : 0);

            if (v != module::version)
              fail (loc) << "incompatible config file " << f <<
                info << "config file version   " << v
                         << (p.second ? "" : " (missing)") <<
                info << "config module version " << module::version <<
                info << "consider reconfiguring " << project (rs) << '@'
                         << out_root;
          }

          source (f, rs, rs);
        }
      }
    }

    bool
    init (scope& rs,
          scope&,
          const location& l,
          unique_ptr<module_base>& mod,
          bool first,
          bool,
          const variable_map& config_hints)
    {
      tracer trace ("config::init");

      if (!first)
      {
        warn (l) << "multiple config module initializations";
        return true;
      }

      l5 ([&]{trace << "for " << rs.out_path ();});

      assert (config_hints.empty ()); // We don't known any hints.

      // Only create the module if we are configuring.
      //
      if (current_mif->id == configure_id)
        mod.reset (new module);

      // Adjust priority for the import pseudo-module so that config.import.*
      // values come first in config.build.
      //
      config::save_module (rs, "import", INT32_MIN);

      // Register alias and fallback rule for the configure meta-operation.
      //
      {
        // We need this rule for out-of-any-project dependencies (e.g.,
        // libraries imported from /usr/lib).
        //
        global_scope->rules.insert<file> (
          configure_id, 0, "config.file", file_rule::instance);

        auto& r (rs.rules);

        r.insert<target> (configure_id, 0, "config", fallback_rule::instance);
        r.insert<file> (configure_id, 0, "config.file", fallback_rule::instance);
        r.insert<alias> (configure_id, 0, "config.alias", alias_rule::instance);
      }

      return true;
    }
  }
}