/* gbp-meson-build-system.c
 *
 * Copyright 2017-2019 Christian Hergert <chergert@redhat.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 */

#define G_LOG_DOMAIN "gbp-meson-build-system"

#include "config.h"

#include <glib/gi18n.h>
#include <json-glib/json-glib.h>
#include <string.h>

#include "gbp-meson-build-system.h"
#include "gbp-meson-build-target.h"
#include "gbp-meson-toolchain.h"

struct _GbpMesonBuildSystem
{
  IdeObject            parent_instance;
  GFile               *project_file;
  IdeCompileCommands  *compile_commands;
  GFileMonitor        *monitor;
  char                *project_version;
  char               **languages;
};

static void async_initable_iface_init (GAsyncInitableIface     *iface);
static void build_system_iface_init   (IdeBuildSystemInterface *iface);

G_DEFINE_FINAL_TYPE_WITH_CODE (GbpMesonBuildSystem, gbp_meson_build_system, IDE_TYPE_OBJECT,
                               G_IMPLEMENT_INTERFACE (G_TYPE_ASYNC_INITABLE, async_initable_iface_init)
                               G_IMPLEMENT_INTERFACE (IDE_TYPE_BUILD_SYSTEM, build_system_iface_init))

enum {
  PROP_0,
  PROP_PROJECT_FILE,
  N_PROPS
};

static GParamSpec *properties [N_PROPS];

static void
gbp_meson_build_system_ensure_config_cb (GObject      *object,
                                         GAsyncResult *result,
                                         gpointer      user_data)
{
  IdeBuildManager *build_manager = (IdeBuildManager *)object;
  g_autoptr(IdeTask) task = user_data;
  g_autoptr(GError) error = NULL;

  g_assert (IDE_IS_BUILD_MANAGER (build_manager));
  g_assert (G_IS_ASYNC_RESULT (result));
  g_assert (IDE_IS_TASK (task));

  if (!ide_build_manager_build_finish (build_manager, result, &error))
    ide_task_return_error (task, g_steal_pointer (&error));
  else
    ide_task_return_boolean (task, TRUE);
}

static void
gbp_meson_build_system_ensure_config_async (GbpMesonBuildSystem *self,
                                            GCancellable        *cancellable,
                                            GAsyncReadyCallback  callback,
                                            gpointer             user_data)
{
  g_autoptr(IdeTask) task = NULL;
  IdeBuildManager *build_manager;
  IdeContext *context;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (!cancellable || G_IS_CANCELLABLE (cancellable));

  task = ide_task_new (self, cancellable, callback, user_data);
  ide_task_set_source_tag (task, gbp_meson_build_system_ensure_config_async);
  ide_task_set_priority (task, G_PRIORITY_LOW);

  context = ide_object_get_context (IDE_OBJECT (self));
  build_manager = ide_build_manager_from_context (context);

  ide_build_manager_build_async (build_manager,
                                   IDE_PIPELINE_PHASE_CONFIGURE,
                                   NULL,
                                   cancellable,
                                   gbp_meson_build_system_ensure_config_cb,
                                   g_steal_pointer (&task));
}

static gboolean
gbp_meson_build_system_ensure_config_finish (GbpMesonBuildSystem  *self,
                                             GAsyncResult         *result,
                                             GError              **error)
{
  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (IDE_IS_TASK (result));

  return ide_task_propagate_boolean (IDE_TASK (result), error);
}

static void
gbp_meson_build_system_monitor_changed (GbpMesonBuildSystem *self,
                                        GFile               *file,
                                        GFile               *other_file,
                                        GFileMonitorEvent    event,
                                        GFileMonitor        *monitor)
{
  IDE_ENTRY;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (!file || G_IS_FILE (file));
  g_assert (!other_file || G_IS_FILE (other_file));
  g_assert (G_IS_FILE_MONITOR (monitor));

  /* Release our previous compile commands */
  g_clear_object (&self->compile_commands);
  g_file_monitor_cancel (monitor);
  g_clear_object (&self->monitor);

  IDE_EXIT;
}

static void
gbp_meson_build_system_monitor (GbpMesonBuildSystem *self,
                                GFile               *file)
{
  g_autoptr(GFileMonitor) monitor = NULL;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (G_IS_FILE (file));

  monitor = g_file_monitor_file (file,
                                 G_FILE_MONITOR_NONE,
                                 NULL,
                                 NULL);
  g_signal_connect_object (monitor,
                           "changed",
                           G_CALLBACK (gbp_meson_build_system_monitor_changed),
                           self,
                           G_CONNECT_SWAPPED);
  g_set_object (&self->monitor, monitor);
}

static void
gbp_meson_build_system_load_commands_load_cb (GObject      *object,
                                              GAsyncResult *result,
                                              gpointer      user_data)
{
  IdeCompileCommands *compile_commands = (IdeCompileCommands *)object;
  GbpMesonBuildSystem *self;
  g_autoptr(IdeTask) task = user_data;
  g_autoptr(GError) error = NULL;

  g_assert (IDE_IS_COMPILE_COMMANDS (compile_commands));
  g_assert (G_IS_ASYNC_RESULT (result));
  g_assert (IDE_IS_TASK (task));

  self = ide_task_get_source_object (task);

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));

  if (!ide_compile_commands_load_finish (compile_commands, result, &error))
    {
      ide_task_return_error (task, g_steal_pointer (&error));
      return;
    }

  g_set_object (&self->compile_commands, compile_commands);
  ide_task_return_pointer (task, g_object_ref (compile_commands), g_object_unref);
}

static void
gbp_meson_build_system_load_commands_config_cb (GObject      *object,
                                                GAsyncResult *result,
                                                gpointer      user_data)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)object;
  g_autoptr(IdeCompileCommands) compile_commands = NULL;
  g_autoptr(IdeTask) task = user_data;
  g_autoptr(GError) error = NULL;
  g_autoptr(GFile) file = NULL;
  g_autofree gchar *path = NULL;
  IdeBuildManager *build_manager;
  IdePipeline *pipeline;
  GCancellable *cancellable;
  IdeContext *context;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (G_IS_ASYNC_RESULT (result));
  g_assert (IDE_IS_TASK (task));

  if (!gbp_meson_build_system_ensure_config_finish (self, result, &error))
    {
      ide_task_return_error (task, g_steal_pointer (&error));
      return;
    }

  context = ide_object_get_context (IDE_OBJECT (self));
  build_manager = ide_build_manager_from_context (context);
  pipeline = ide_build_manager_get_pipeline (build_manager);

  if (pipeline == NULL)
    {
      /* Unlikely, but possible */
      ide_task_return_new_error (task,
                                 G_IO_ERROR,
                                 G_IO_ERROR_FAILED,
                                 "No build pipeline is available");
      return;
    }

  path = ide_pipeline_build_builddir_path (pipeline, "compile_commands.json", NULL);

  if (!g_file_test (path, G_FILE_TEST_IS_REGULAR))
    {
      /* Unlikely, but possible */
      ide_task_return_new_error (task,
                                 G_IO_ERROR,
                                 G_IO_ERROR_NOT_FOUND,
                                 "Failed to locate compile_commands.json");
      return;
    }

  compile_commands = ide_compile_commands_new ();
  file = g_file_new_for_path (path);
  cancellable = ide_task_get_cancellable (task);

  ide_compile_commands_load_async (compile_commands,
                                   file,
                                   cancellable,
                                   gbp_meson_build_system_load_commands_load_cb,
                                   g_steal_pointer (&task));

  gbp_meson_build_system_monitor (self, file);
}

static void
gbp_meson_build_system_load_commands_async (GbpMesonBuildSystem *self,
                                            GCancellable        *cancellable,
                                            GAsyncReadyCallback  callback,
                                            gpointer             user_data)
{
  g_autoptr(IdeTask) task = NULL;
  g_autofree gchar *path = NULL;
  IdeBuildManager *build_manager;
  IdePipeline *pipeline;
  IdeContext *context;

  IDE_ENTRY;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (!cancellable || G_IS_CANCELLABLE (cancellable));

  task = ide_task_new (self, cancellable, callback, user_data);
  ide_task_set_source_tag (task, gbp_meson_build_system_load_commands_async);

  /*
   * If we've already load the compile commands database, use it and
   * short circuit as early as we can to avoid progressing the build
   * pipeline unnecessarily.
   */

  if (self->compile_commands != NULL)
    {
      ide_task_return_pointer (task,
                               g_object_ref (self->compile_commands),
                               g_object_unref);
      IDE_EXIT;
    }

  /*
   * If the build pipeline has been previously configured, we might
   * already have a "compile_commands.json" file in the build directory
   * that we can reuse.
   */

  context = ide_object_get_context (IDE_OBJECT (self));
  build_manager = ide_build_manager_from_context (context);
  pipeline = ide_build_manager_get_pipeline (build_manager);

  /*
   * Because we're accessing the pipeline directly, we need to be careful
   * here about whether or not it is setup fully. It may be delayed due
   * to device initialization.
   */
  if (pipeline == NULL || !ide_pipeline_is_ready (pipeline))
    {
      ide_task_return_new_error (task,
                                 G_IO_ERROR,
                                 G_IO_ERROR_NOT_INITIALIZED,
                                 "There is no pipeline to access");
      IDE_EXIT;
    }

  path = ide_pipeline_build_builddir_path (pipeline, "compile_commands.json", NULL);

  if (g_file_test (path, G_FILE_TEST_IS_REGULAR))
    {
      g_autoptr(IdeCompileCommands) compile_commands = NULL;
      g_autoptr(GFile) file = NULL;

      compile_commands = ide_compile_commands_new ();
      file = g_file_new_for_path (path);

      ide_compile_commands_load_async (compile_commands,
                                       file,
                                       cancellable,
                                       gbp_meson_build_system_load_commands_load_cb,
                                       g_steal_pointer (&task));

      gbp_meson_build_system_monitor (self, file);

      IDE_EXIT;
    }

  /*
   * Because we're accessing the pipeline directly, we need to be careful
   * here about whether or not it is setup fully. It may be delayed due
   * to device initialization.
   */
  if (!ide_pipeline_is_ready (pipeline))
    {
      ide_task_return_new_error (task,
                                 G_IO_ERROR,
                                 G_IO_ERROR_NOT_INITIALIZED,
                                 "The pipeline is not yet ready to handle requests");
      IDE_EXIT;
    }

  /*
   * It looks like we need to ensure the build pipeline advances to the the
   * CONFIGURE phase so that meson has generated a new compile_commands.json
   * that we can load.
   */

  gbp_meson_build_system_ensure_config_async (self,
                                              cancellable,
                                              gbp_meson_build_system_load_commands_config_cb,
                                              g_steal_pointer (&task));

  IDE_EXIT;
}

static IdeCompileCommands *
gbp_meson_build_system_load_commands_finish (GbpMesonBuildSystem  *self,
                                             GAsyncResult         *result,
                                             GError              **error)
{
  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (IDE_IS_TASK (result));

  return ide_task_propagate_pointer (IDE_TASK (result), error);
}

static void
gbp_meson_build_system_set_project_file (GbpMesonBuildSystem *self,
                                         GFile               *file)
{
  g_autofree gchar *name = NULL;

  g_assert (IDE_IS_MAIN_THREAD ());
  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (G_IS_FILE (file));

  name = g_file_get_basename (file);

  if (ide_str_equal0 (name, "meson.build"))
    self->project_file = g_file_dup (file);
  else
    self->project_file = g_file_get_child (file, "meson.build");
}

static void
gbp_meson_build_system_finalize (GObject *object)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)object;

  g_clear_object (&self->project_file);
  g_clear_object (&self->compile_commands);
  g_clear_object (&self->monitor);
  g_clear_pointer (&self->project_version, g_free);
  g_clear_pointer (&self->languages, g_strfreev);

  G_OBJECT_CLASS (gbp_meson_build_system_parent_class)->finalize (object);
}

static void
gbp_meson_build_system_get_property (GObject    *object,
                                     guint       prop_id,
                                     GValue     *value,
                                     GParamSpec *pspec)
{
  GbpMesonBuildSystem *self = GBP_MESON_BUILD_SYSTEM (object);

  switch (prop_id)
    {
    case PROP_PROJECT_FILE:
      g_value_set_object (value, self->project_file);
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    }
}

static void
gbp_meson_build_system_set_property (GObject      *object,
                                     guint         prop_id,
                                     const GValue *value,
                                     GParamSpec   *pspec)
{
  GbpMesonBuildSystem *self = GBP_MESON_BUILD_SYSTEM (object);

  switch (prop_id)
    {
    case PROP_PROJECT_FILE:
      gbp_meson_build_system_set_project_file (self, g_value_get_object (value));
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    }
}

static void
gbp_meson_build_system_class_init (GbpMesonBuildSystemClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  object_class->finalize = gbp_meson_build_system_finalize;
  object_class->get_property = gbp_meson_build_system_get_property;
  object_class->set_property = gbp_meson_build_system_set_property;

  properties [PROP_PROJECT_FILE] =
    g_param_spec_object ("project-file",
                         "Project File",
                         "The primary meson.build for the project",
                         G_TYPE_FILE,
                         (G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));

  g_object_class_install_properties (object_class, N_PROPS, properties);
}

static void
gbp_meson_build_system_init (GbpMesonBuildSystem *self)
{
}

static gchar *
gbp_meson_build_system_get_id (IdeBuildSystem *build_system)
{
  return g_strdup ("meson");
}

static gchar *
gbp_meson_build_system_get_display_name (IdeBuildSystem *build_system)
{
  return g_strdup (_("Meson"));
}

static gint
gbp_meson_build_system_get_priority (IdeBuildSystem *build_system)
{
  return -400;
}

static void
gbp_meson_build_system_get_build_flags_for_files_cb (GObject      *object,
                                                     GAsyncResult *result,
                                                     gpointer      user_data)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)object;
  g_autoptr(IdeCompileCommands) compile_commands = NULL;
  g_autoptr(IdeTask) task = user_data;
  g_autoptr(GError) error = NULL;
  g_autoptr(GHashTable) ret = NULL;
  g_auto(GStrv) system_includes = NULL;
  IdeConfigManager *config_manager;
  IdeConfig *config;
  IdeContext *context;
  IdeRuntime *runtime;
  GPtrArray *files;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (G_IS_ASYNC_RESULT (result));
  g_assert (IDE_IS_TASK (task));

  if (!(compile_commands = gbp_meson_build_system_load_commands_finish (self, result, &error)))
    {
      ide_task_return_error (task, g_steal_pointer (&error));
      return;
    }

  files = ide_task_get_task_data (task);
  g_assert (files != NULL);

  /* Get non-standard system includes */
  context = ide_object_get_context (IDE_OBJECT (self));
  config_manager = ide_config_manager_from_context (context);
  config = ide_config_manager_get_current (config_manager);
  if (NULL != (runtime = ide_config_get_runtime (config)))
    system_includes = ide_runtime_get_system_include_dirs (runtime);

  ret = g_hash_table_new_full (g_file_hash,
                               (GEqualFunc)g_file_equal,
                               g_object_unref,
                               (GDestroyNotify)g_strfreev);

  for (guint i = 0; i < files->len; i++)
    {
      GFile *file = g_ptr_array_index (files, i);
      g_auto(GStrv) flags = NULL;

      flags = ide_compile_commands_lookup (compile_commands, file,
                                           (const gchar * const *)system_includes,
                                           NULL, NULL);
      g_hash_table_insert (ret, g_object_ref (file), g_steal_pointer (&flags));
    }

  ide_task_return_pointer (task, g_steal_pointer (&ret), g_hash_table_unref);
}

static void
gbp_meson_build_system_get_build_flags_cb (GObject      *object,
                                           GAsyncResult *result,
                                           gpointer      user_data)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)object;
  g_autoptr(IdeCompileCommands) compile_commands = NULL;
  g_autoptr(IdeTask) task = user_data;
  g_autoptr(GError) error = NULL;
  g_autoptr(GFile) directory = NULL;
  g_auto(GStrv) system_includes = NULL;
  g_auto(GStrv) ret = NULL;
  IdeConfigManager *config_manager;
  IdeContext *context;
  IdeConfig *config;
  IdeRuntime *runtime;
  GFile *file;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (G_IS_ASYNC_RESULT (result));
  g_assert (IDE_IS_TASK (task));

  compile_commands = gbp_meson_build_system_load_commands_finish (self, result, &error);

  if (compile_commands == NULL)
    {
      ide_task_return_error (task, g_steal_pointer (&error));
      return;
    }

  file = ide_task_get_task_data (task);
  g_assert (G_IS_FILE (file));

  /* Get non-standard system includes */
  context = ide_object_get_context (IDE_OBJECT (self));
  config_manager = ide_config_manager_from_context (context);
  config = ide_config_manager_get_current (config_manager);
  if (NULL != (runtime = ide_config_get_runtime (config)))
    system_includes = ide_runtime_get_system_include_dirs (runtime);

  ret = ide_compile_commands_lookup (compile_commands,
                                     file,
                                     (const gchar * const *)system_includes,
                                     &directory,
                                     &error);

  if (ret == NULL)
    ide_task_return_error (task, g_steal_pointer (&error));
  else
    ide_task_return_pointer (task, g_steal_pointer (&ret), g_strfreev);
}

static void
gbp_meson_build_system_get_build_flags_async (IdeBuildSystem      *build_system,
                                              GFile               *file,
                                              GCancellable        *cancellable,
                                              GAsyncReadyCallback  callback,
                                              gpointer             user_data)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)build_system;
  g_autoptr(IdeTask) task = NULL;

  IDE_ENTRY;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (G_IS_FILE (file));
  g_assert (!cancellable || G_IS_CANCELLABLE (cancellable));

  task = ide_task_new (self, cancellable, callback, user_data);
  ide_task_set_priority (task, G_PRIORITY_LOW);
  ide_task_set_source_tag (task, gbp_meson_build_system_get_build_flags_async);
  ide_task_set_task_data (task, g_object_ref (file), g_object_unref);

  gbp_meson_build_system_load_commands_async (self,
                                              cancellable,
                                              gbp_meson_build_system_get_build_flags_cb,
                                              g_steal_pointer (&task));

  IDE_EXIT;
}

static gchar **
gbp_meson_build_system_get_build_flags_finish (IdeBuildSystem  *build_system,
                                               GAsyncResult    *result,
                                               GError         **error)
{
  g_assert (GBP_IS_MESON_BUILD_SYSTEM (build_system));
  g_assert (IDE_IS_TASK (result));

  return ide_task_propagate_pointer (IDE_TASK (result), error);
}

static void
gbp_meson_build_system_get_build_flags_for_files_async (IdeBuildSystem      *build_system,
                                                        GPtrArray           *files,
                                                        GCancellable        *cancellable,
                                                        GAsyncReadyCallback  callback,
                                                        gpointer             user_data)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)build_system;
  g_autoptr(IdeTask) task = NULL;
  g_autoptr(GPtrArray) copy = NULL;

  IDE_ENTRY;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (files != NULL);
  g_assert (!cancellable || G_IS_CANCELLABLE (cancellable));

  task = ide_task_new (self, cancellable, callback, user_data);
  ide_task_set_source_tag (task, gbp_meson_build_system_get_build_flags_async);
  ide_task_set_priority (task, G_PRIORITY_LOW);

  /* Make our own copy of the array */
  copy = g_ptr_array_new_with_free_func (g_object_unref);
  for (guint i = 0; i < files->len; i++)
    g_ptr_array_add (copy, g_object_ref (g_ptr_array_index (files, i)));
  ide_task_set_task_data (task, g_steal_pointer (&copy), g_ptr_array_unref);

  gbp_meson_build_system_load_commands_async (self,
                                              cancellable,
                                              gbp_meson_build_system_get_build_flags_for_files_cb,
                                              g_steal_pointer (&task));

  IDE_EXIT;
}

static GHashTable *
gbp_meson_build_system_get_build_flags_for_files_finish (IdeBuildSystem  *build_system,
                                                         GAsyncResult    *result,
                                                         GError         **error)
{
  g_assert (GBP_IS_MESON_BUILD_SYSTEM (build_system));
  g_assert (IDE_IS_TASK (result));

  return ide_task_propagate_pointer (IDE_TASK (result), error);
}

static gchar *
gbp_meson_build_system_get_builddir (IdeBuildSystem   *build_system,
                                     IdePipeline *pipeline)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)build_system;
  IdeConfig *config;
  IdeBuildLocality locality;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (IDE_IS_PIPELINE (pipeline));

  /*
   * If the build configuration requires that we do an in tree build (yuck),
   * then use "_build" as our build directory to build in-tree.
   */

  config = ide_pipeline_get_config (pipeline);
  locality = ide_config_get_locality (config);

  if ((locality & IDE_BUILD_LOCALITY_OUT_OF_TREE) == 0)
    {
      g_autoptr(GFile) parent = g_file_get_parent (self->project_file);
      g_autofree gchar *path = g_file_get_path (parent);
      g_autofree gchar *builddir = g_build_filename (path, "_build", NULL);

      return g_steal_pointer (&builddir);
    }

  return NULL;
}

static gboolean
gbp_meson_build_system_supports_toolchain (IdeBuildSystem *self,
                                           IdeToolchain   *toolchain)
{
  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (IDE_IS_TOOLCHAIN (toolchain));

  if (GBP_IS_MESON_TOOLCHAIN (toolchain))
    return TRUE;

  return FALSE;
}

static gchar *
gbp_meson_build_system_get_project_version (IdeBuildSystem *build_system)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)build_system;

  g_assert (IDE_IS_MAIN_THREAD ());
  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));

  return g_strdup (self->project_version);
}

static gboolean
gbp_meson_build_system_supports_language (IdeBuildSystem *system,
                                          const char     *language)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)system;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (language != NULL);

  if (self->languages != NULL)
    return g_strv_contains ((const char * const *)self->languages, language);

  return FALSE;
}

static void
build_system_iface_init (IdeBuildSystemInterface *iface)
{
  iface->get_id = gbp_meson_build_system_get_id;
  iface->get_display_name = gbp_meson_build_system_get_display_name;
  iface->get_priority = gbp_meson_build_system_get_priority;
  iface->get_build_flags_async = gbp_meson_build_system_get_build_flags_async;
  iface->get_build_flags_finish = gbp_meson_build_system_get_build_flags_finish;
  iface->get_build_flags_for_files_async = gbp_meson_build_system_get_build_flags_for_files_async;
  iface->get_build_flags_for_files_finish = gbp_meson_build_system_get_build_flags_for_files_finish;
  iface->get_builddir = gbp_meson_build_system_get_builddir;
  iface->get_project_version = gbp_meson_build_system_get_project_version;
  iface->supports_toolchain = gbp_meson_build_system_supports_toolchain;
  iface->supports_language = gbp_meson_build_system_supports_language;
}


static char **
split_language (gchar *raw_language_string)
{
  g_autofree gchar *copy = NULL;
  GString *str = g_string_new (raw_language_string);
  g_string_replace (str, "'", "", -1);
  g_string_replace (str, " ", "", -1);
  g_string_replace (str, "\n", "", -1);
  copy = g_string_free (str, FALSE);

  return g_strsplit (copy, ",", -1);
}

/**
 * This could be
 * 1) without language
 * 2) 'projectname', 'c' with only one language
 * 3) 'projectname', 'c', 'c++' with variadic as languages
 * 4) 'projectname', ['c', 'c++'] with an list as languages
 */
char **
_gbp_meson_build_system_parse_languages (const gchar *raw_language_string)
{
  g_autofree gchar *language_string = NULL;
  gchar *cur = (gchar *) raw_language_string;
  gchar *cur2;
  cur = g_strstr_len (cur, -1, ",");
  if (cur == NULL) goto failure;
  cur++;
  cur2 = cur;
  while (*cur2 != ':' || *cur2 == '\0')
    {
      if (*cur2 == '[')
        {
          cur2 = g_strstr_len (cur2, -1, "]");
          if (cur2 == NULL) goto failure;
          cur2++;
          break;
        }
      cur2++;
    }
  if (*cur2 == ':') while(*cur2 != ',') cur2--;
  if (cur2-cur <= 0) goto failure;
  language_string = g_strndup (cur, cur2-cur);

  if (strstr(language_string, "[") || strstr(language_string, "]"))
    {
      gchar *begin = NULL;
      gchar *end = NULL;
      g_autofree gchar *copy = NULL;

      if ((begin = strstr(language_string, "[")) == NULL) goto failure;
      if ((end = strstr(language_string, "]")) == NULL) goto failure;
      copy = g_strndup (begin + 1, end-begin - 1);

      return split_language (copy);
    }

  return split_language (language_string);

failure:
  return NULL;
}

static void
extract_metadata (GbpMesonBuildSystem *self,
                  const gchar         *contents)
{
  const gchar *ptr;
  g_autoptr(GRegex) regex = NULL;
  g_autoptr(GMatchInfo) match_info = NULL;

  g_assert (IDE_IS_MAIN_THREAD ());
  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (contents != NULL);

  ptr = strstr (contents, "version:");

  if (ptr > contents)
    {
      const gchar *prev = ptr - 1;
      gunichar ch = g_utf8_get_char (prev);

      if (g_unichar_isspace (ch) || ch == ',')
        {
          const gchar *begin;
          const gchar *end;

          ptr++;

          for (ptr++; *ptr && *ptr != '\''; ptr = g_utf8_next_char (ptr)) ;
          if (!*ptr)
            goto failure;

          ptr++;
          begin = ptr;

          for (ptr++; *ptr && *ptr != '\''; ptr = g_utf8_next_char (ptr)) ;
          if (!*ptr)
            goto failure;

          end = ptr;

          g_free (self->project_version);
          self->project_version = g_strndup (begin, end - begin);
        }
    }

  regex = g_regex_new ("^project\\((.*)\\)", G_REGEX_DOTALL | G_REGEX_MULTILINE | G_REGEX_UNGREEDY, 0, NULL);
  g_regex_match (regex, contents, 0, &match_info);
  while (g_match_info_matches (match_info))
    {
      const gchar *str = g_match_info_fetch (match_info, 1);
      self->languages = _gbp_meson_build_system_parse_languages (str);

      g_match_info_next (match_info, NULL);
    }

failure:

  return;
}

static void
gbp_meson_build_system_notify_pipeline (GbpMesonBuildSystem *self,
                                        GParamSpec          *pspec,
                                        IdeBuildManager     *build_manager)
{
  IDE_ENTRY;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (pspec != NULL);
  g_assert (IDE_IS_BUILD_MANAGER (build_manager));

  /*
   * We need to regenerate compile commands when the build pipeline
   * changes so that we get the updated commands.
   */
  g_clear_object (&self->compile_commands);

  IDE_EXIT;
}

static void
gbp_meson_build_system_init_async (GAsyncInitable      *initable,
                                   gint                 io_priority,
                                   GCancellable        *cancellable,
                                   GAsyncReadyCallback  callback,
                                   gpointer             user_data)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)initable;
  g_autoptr(IdeTask) task = NULL;
  g_autofree gchar *contents = NULL;
  IdeBuildManager *build_manager;
  IdeContext *context;
  gsize len = 0;

  IDE_ENTRY;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (G_IS_FILE (self->project_file));
  g_assert (!cancellable || G_IS_CANCELLABLE (cancellable));

  context = ide_object_get_context (IDE_OBJECT (self));
  g_assert (IDE_IS_CONTEXT (context));

  build_manager = ide_build_manager_from_context (context);
  g_assert (IDE_IS_BUILD_MANAGER (build_manager));

  task = ide_task_new (self, cancellable, callback, user_data);
  ide_task_set_source_tag (task, gbp_meson_build_system_init_async);
  ide_task_set_priority (task, io_priority);
  ide_task_set_task_data (task, g_object_ref (self->project_file), g_object_unref);

  if (g_file_load_contents (self->project_file, cancellable, &contents, &len, NULL, NULL))
    extract_metadata (self, contents);

  /*
   * We want to be notified of any changes to the current build manager.
   * This will let us invalidate our compile_commands.json when it changes.
   */
  g_signal_connect_object (build_manager,
                           "notify::pipeline",
                           G_CALLBACK (gbp_meson_build_system_notify_pipeline),
                           self,
                           G_CONNECT_SWAPPED);

  ide_task_return_boolean (task, TRUE);

  IDE_EXIT;
}

static gboolean
gbp_meson_build_system_init_finish (GAsyncInitable  *initable,
                                    GAsyncResult    *result,
                                    GError         **error)
{
  GbpMesonBuildSystem *self = (GbpMesonBuildSystem *)initable;
  g_autoptr(GFile) project_file = NULL;

  IDE_ENTRY;

  g_assert (GBP_IS_MESON_BUILD_SYSTEM (self));
  g_assert (IDE_IS_TASK (result));

  project_file = ide_task_propagate_pointer (IDE_TASK (result), error);
  if (g_set_object (&self->project_file, project_file))
    g_object_notify_by_pspec (G_OBJECT (self), properties [PROP_PROJECT_FILE]);

  IDE_RETURN (project_file != NULL);
}

static void
async_initable_iface_init (GAsyncInitableIface *iface)
{
  iface->init_async = gbp_meson_build_system_init_async;
  iface->init_finish = gbp_meson_build_system_init_finish;
}

const gchar * const *
gbp_meson_build_system_get_languages (GbpMesonBuildSystem *self)
{
  g_return_val_if_fail (GBP_IS_MESON_BUILD_SYSTEM (self), NULL);

  return (const gchar * const *)self->languages;
}

char *
gbp_meson_build_system_get_project_dir (GbpMesonBuildSystem *self)
{
  g_autoptr(GFile) workdir = NULL;
  g_autofree char *base = NULL;
  IdeContext *context;

  g_return_val_if_fail (GBP_IS_MESON_BUILD_SYSTEM (self), NULL);

  context = ide_object_get_context (IDE_OBJECT (self));
  workdir = ide_context_ref_workdir (context);

  if (self->project_file == NULL)
    return g_strdup (g_file_peek_path (workdir));

  base = g_file_get_basename (self->project_file);

  if (strcasecmp (base, "meson.build") == 0)
    {
      g_autoptr(GFile) parent = g_file_get_parent (self->project_file);
      return g_file_get_path (parent);
    }

  return g_file_get_path (self->project_file);
}

char *
gbp_meson_build_system_locate_meson (GbpMesonBuildSystem *self,
                                     IdePipeline         *pipeline)
{
  IdeConfig *config;

  g_return_val_if_fail (!self || GBP_IS_MESON_BUILD_SYSTEM (self), NULL);
  g_return_val_if_fail (!pipeline || IDE_IS_PIPELINE (pipeline), NULL);

  if ((config = ide_pipeline_get_config (pipeline)))
    {
      const char *envvar = ide_config_getenv (config, "MESON");

      if (envvar != NULL)
        return g_strdup (envvar);
    }

  return g_strdup ("meson");
}

char *
gbp_meson_build_system_locate_ninja (GbpMesonBuildSystem *self,
                                     IdePipeline         *pipeline)
{
  IdeConfig *config = NULL;

  g_return_val_if_fail (!self || GBP_IS_MESON_BUILD_SYSTEM (self), NULL);
  g_return_val_if_fail (!pipeline || IDE_IS_PIPELINE (pipeline), NULL);

  if (pipeline != NULL && config == NULL)
    config = ide_pipeline_get_config (pipeline);

  /* First check NINJA=path override in IdeConfig */
  if (config != NULL)
    {
      const char *envvar = ide_config_getenv (config, "NINJA");

      if (envvar != NULL)
        return g_strdup (envvar);
    }

  if (pipeline != NULL)
    {
      static const char *known_aliases[] = { "ninja", "ninja-build" };

      for (guint i = 0; i < G_N_ELEMENTS (known_aliases); i++)
        {
          if (ide_pipeline_contains_program_in_path (pipeline, known_aliases[i], NULL))
            return g_strdup (known_aliases[i]);
        }
    }

  /* Fallback to "ninja" and hope for the best */
  return g_strdup ("ninja");
}
