// Copyright (C) 2008 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.gerrit.server.project;

import static java.nio.charset.StandardCharsets.UTF_8;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.io.Files;
import com.google.gerrit.common.data.AccessSection;
import com.google.gerrit.common.data.GroupReference;
import com.google.gerrit.common.data.LabelType;
import com.google.gerrit.common.data.LabelTypes;
import com.google.gerrit.common.data.Permission;
import com.google.gerrit.common.data.PermissionRule;
import com.google.gerrit.extensions.common.InheritableBoolean;
import com.google.gerrit.reviewdb.client.AccountGroup;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.reviewdb.client.RefNames;
import com.google.gerrit.rules.PrologEnvironment;
import com.google.gerrit.rules.RulesCache;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.account.CapabilityCollection;
import com.google.gerrit.server.account.GroupMembership;
import com.google.gerrit.server.config.AllProjectsName;
import com.google.gerrit.server.config.SitePaths;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.gerrit.server.git.ProjectConfig;
import com.google.gerrit.server.git.ProjectLevelConfig;
import com.google.inject.Inject;
import com.google.inject.assistedinject.Assisted;

import com.googlecode.prolog_cafe.compiler.CompileException;
import com.googlecode.prolog_cafe.lang.PrologMachineCopy;

import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.Repository;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

/** Cached information on a project. */
public class ProjectState {
  private static final Logger log =
      LoggerFactory.getLogger(ProjectState.class);

  public interface Factory {
    ProjectState create(ProjectConfig config);
  }

  private final boolean isAllProjects;
  private final SitePaths sitePaths;
  private final AllProjectsName allProjectsName;
  private final ProjectCache projectCache;
  private final ProjectControl.AssistedFactory projectControlFactory;
  private final PrologEnvironment.Factory envFactory;
  private final GitRepositoryManager gitMgr;
  private final RulesCache rulesCache;
  private final List<CommentLinkInfo> commentLinks;

  private final ProjectConfig config;
  private final Map<String, ProjectLevelConfig> configs;
  private final Set<AccountGroup.UUID> localOwners;

  /** Prolog rule state. */
  private volatile PrologMachineCopy rulesMachine;

  /** Last system time the configuration's revision was examined. */
  private volatile long lastCheckTime;

  /** Local access sections, wrapped in SectionMatchers for faster evaluation. */
  private volatile List<SectionMatcher> localAccessSections;

  /** Theme information loaded from site_path/themes. */
  private volatile ThemeInfo theme;

  /** If this is all projects, the capabilities used by the server. */
  private final CapabilityCollection capabilities;

  @Inject
  public ProjectState(
      final SitePaths sitePaths,
      final ProjectCache projectCache,
      final AllProjectsName allProjectsName,
      final ProjectControl.AssistedFactory projectControlFactory,
      final PrologEnvironment.Factory envFactory,
      final GitRepositoryManager gitMgr,
      final RulesCache rulesCache,
      final List<CommentLinkInfo> commentLinks,
      @Assisted final ProjectConfig config) {
    this.sitePaths = sitePaths;
    this.projectCache = projectCache;
    this.isAllProjects = config.getProject().getNameKey().equals(allProjectsName);
    this.allProjectsName = allProjectsName;
    this.projectControlFactory = projectControlFactory;
    this.envFactory = envFactory;
    this.gitMgr = gitMgr;
    this.rulesCache = rulesCache;
    this.commentLinks = commentLinks;
    this.config = config;
    this.configs = Maps.newHashMap();
    this.capabilities = isAllProjects
      ? new CapabilityCollection(config.getAccessSection(AccessSection.GLOBAL_CAPABILITIES))
      : null;

    if (isAllProjects && !Permission.canBeOnAllProjects(AccessSection.ALL, Permission.OWNER)) {
      localOwners = Collections.emptySet();
    } else {
      HashSet<AccountGroup.UUID> groups = new HashSet<AccountGroup.UUID>();
      AccessSection all = config.getAccessSection(AccessSection.ALL);
      if (all != null) {
        Permission owner = all.getPermission(Permission.OWNER);
        if (owner != null) {
          for (PermissionRule rule : owner.getRules()) {
            GroupReference ref = rule.getGroup();
            if (ref.getUUID() != null) {
              groups.add(ref.getUUID());
            }
          }
        }
      }
      localOwners = Collections.unmodifiableSet(groups);
    }
  }

  boolean needsRefresh(long generation) {
    if (generation <= 0) {
      return isRevisionOutOfDate();
    }
    if (lastCheckTime != generation) {
      lastCheckTime = generation;
      return isRevisionOutOfDate();
    }
    return false;
  }

  private boolean isRevisionOutOfDate() {
    try {
      Repository git = gitMgr.openRepository(getProject().getNameKey());
      try {
        Ref ref = git.getRef(RefNames.REFS_CONFIG);
        if (ref == null || ref.getObjectId() == null) {
          return true;
        }
        return !ref.getObjectId().equals(config.getRevision());
      } finally {
        git.close();
      }
    } catch (IOException gone) {
      return true;
    }
  }

  /**
   * @return cached computation of all global capabilities. This should only be
   *         invoked on the state from {@link ProjectCache#getAllProjects()}.
   *         Null on any other project.
   */
  public CapabilityCollection getCapabilityCollection() {
    return capabilities;
  }

  /** @return Construct a new PrologEnvironment for the calling thread. */
  public PrologEnvironment newPrologEnvironment() throws CompileException {
    PrologMachineCopy pmc = rulesMachine;
    if (pmc == null) {
      pmc = rulesCache.loadMachine(
          getProject().getNameKey(),
          config.getRulesId());
      rulesMachine = pmc;
    }
    return envFactory.create(pmc);
  }

  /**
   * Like {@link #newPrologEnvironment()} but instead of reading the rules.pl
   * read the provided input stream.
   *
   * @param name a name of the input stream. Could be any name.
   * @param in InputStream to read prolog rules from
   * @throws CompileException
   */
  public PrologEnvironment newPrologEnvironment(String name, InputStream in)
      throws CompileException {
    PrologMachineCopy pmc = rulesCache.loadMachine(name, in);
    return envFactory.create(pmc);
  }

  public Project getProject() {
    return config.getProject();
  }

  public ProjectConfig getConfig() {
    return config;
  }

  public ProjectLevelConfig getConfig(String fileName) {
    if (configs.containsKey(fileName)) {
      return configs.get(fileName);
    }

    ProjectLevelConfig cfg = new ProjectLevelConfig(fileName, this);
    try {
      Repository git = gitMgr.openRepository(getProject().getNameKey());
      try {
        cfg.load(git);
      } finally {
        git.close();
      }
    } catch (IOException e) {
      log.warn("Failed to load " + fileName + " for " + getProject().getName(), e);
    } catch (ConfigInvalidException e) {
      log.warn("Failed to load " + fileName + " for " + getProject().getName(), e);
    }

    configs.put(fileName, cfg);
    return cfg;
  }

  public long getMaxObjectSizeLimit() {
    return config.getMaxObjectSizeLimit();
  }

  /** Get the sections that pertain only to this project. */
  List<SectionMatcher> getLocalAccessSections() {
    List<SectionMatcher> sm = localAccessSections;
    if (sm == null) {
      Collection<AccessSection> fromConfig = config.getAccessSections();
      sm = new ArrayList<SectionMatcher>(fromConfig.size());
      for (AccessSection section : fromConfig) {
        if (isAllProjects) {
          List<Permission> copy =
              Lists.newArrayListWithCapacity(section.getPermissions().size());
          for (Permission p : section.getPermissions()) {
            if (Permission.canBeOnAllProjects(section.getName(), p.getName())) {
              copy.add(p);
            }
          }
          section = new AccessSection(section.getName());
          section.setPermissions(copy);
        }

        SectionMatcher matcher = SectionMatcher.wrap(getProject().getNameKey(),
            section);
        if (matcher != null) {
          sm.add(matcher);
        }
      }
      localAccessSections = sm;
    }
    return sm;
  }

  /**
   * Obtain all local and inherited sections. This collection is looked up
   * dynamically and is not cached. Callers should try to cache this result
   * per-request as much as possible.
   */
  List<SectionMatcher> getAllSections() {
    if (isAllProjects) {
      return getLocalAccessSections();
    }

    List<SectionMatcher> all = Lists.newArrayList();
    for (ProjectState s : tree()) {
      all.addAll(s.getLocalAccessSections());
    }
    return all;
  }

  /**
   * @return all {@link AccountGroup}'s to which the owner privilege for
   *         'refs/*' is assigned for this project (the local owners), if there
   *         are no local owners the local owners of the nearest parent project
   *         that has local owners are returned
   */
  public Set<AccountGroup.UUID> getOwners() {
    for (ProjectState p : tree()) {
      if (!p.localOwners.isEmpty()) {
        return p.localOwners;
      }
    }
    return Collections.emptySet();
  }

  /**
   * @return true if any of the groups listed in {@code groups} was declared to
   *         be an owner of this project, or one of its parent projects..
   */
  boolean isOwner(final GroupMembership groups) {
    return Iterables.any(tree(), new Predicate<ProjectState>() {
      @Override
      public boolean apply(ProjectState in) {
        return groups.containsAnyOf(in.localOwners);
      }
    });
  }

  public ProjectControl controlFor(final CurrentUser user) {
    return projectControlFactory.create(user, this);
  }

  /**
   * @return an iterable that walks through this project and then the parents of
   *         this project. Starts from this project and progresses up the
   *         hierarchy to All-Projects.
   */
  public Iterable<ProjectState> tree() {
    return new Iterable<ProjectState>() {
      @Override
      public Iterator<ProjectState> iterator() {
        return new ProjectHierarchyIterator(
            projectCache, allProjectsName,
            ProjectState.this);
      }
    };
  }

  /**
   * @return an iterable that walks in-order from All-Projects through the
   *     project hierarchy to this project.
   */
  public Iterable<ProjectState> treeInOrder() {
    List<ProjectState> projects = Lists.newArrayList(tree());
    Collections.reverse(projects);
    return projects;
  }

  /**
   * @return an iterable that walks through the parents of this project. Starts
   *         from the immediate parent of this project and progresses up the
   *         hierarchy to All-Projects.
   */
  public Iterable<ProjectState> parents() {
    return Iterables.skip(tree(), 1);
  }

  public boolean isAllProjects() {
    return isAllProjects;
  }

  public boolean isUseContributorAgreements() {
    return getInheritableBoolean(new Function<Project, InheritableBoolean>() {
      @Override
      public InheritableBoolean apply(Project input) {
        return input.getUseContributorAgreements();
      }
    });
  }

  public boolean isUseContentMerge() {
    return getInheritableBoolean(new Function<Project, InheritableBoolean>() {
      @Override
      public InheritableBoolean apply(Project input) {
        return input.getUseContentMerge();
      }
    });
  }

  public boolean isUseSignedOffBy() {
    return getInheritableBoolean(new Function<Project, InheritableBoolean>() {
      @Override
      public InheritableBoolean apply(Project input) {
        return input.getUseSignedOffBy();
      }
    });
  }

  public boolean isRequireChangeID() {
    return getInheritableBoolean(new Function<Project, InheritableBoolean>() {
      @Override
      public InheritableBoolean apply(Project input) {
        return input.getRequireChangeID();
      }
    });
  }

  public LabelTypes getLabelTypes() {
    Map<String, LabelType> types = Maps.newLinkedHashMap();
    for (ProjectState s : treeInOrder()) {
      for (LabelType type : s.getConfig().getLabelSections().values()) {
        String lower = type.getName().toLowerCase();
        LabelType old = types.get(lower);
        if (old == null || old.canOverride()) {
          types.put(lower, type);
        }
      }
    }
    List<LabelType> all = Lists.newArrayListWithCapacity(types.size());
    for (LabelType type : types.values()) {
      if (!type.getValues().isEmpty()) {
        all.add(type);
      }
    }
    return new LabelTypes(Collections.unmodifiableList(all));
  }

  public List<CommentLinkInfo> getCommentLinks() {
    Map<String, CommentLinkInfo> cls = Maps.newLinkedHashMap();
    for (CommentLinkInfo cl : commentLinks) {
      cls.put(cl.name.toLowerCase(), cl);
    }
    for (ProjectState s : treeInOrder()) {
      for (CommentLinkInfo cl : s.getConfig().getCommentLinkSections()) {
        String name = cl.name.toLowerCase();
        if (cl.isOverrideOnly()) {
          CommentLinkInfo parent = cls.get(name);
          if (parent == null) {
            continue; // Ignore invalid overrides.
          }
          cls.put(name, cl.inherit(parent));
        } else {
          cls.put(name, cl);
        }
      }
    }
    return ImmutableList.copyOf(cls.values());
  }

  public ThemeInfo getTheme() {
    ThemeInfo theme = this.theme;
    if (theme == null) {
      synchronized (this) {
        theme = this.theme;
        if (theme == null) {
          theme = loadTheme();
          this.theme = theme;
        }
      }
    }
    if (theme == ThemeInfo.INHERIT) {
      ProjectState parent = Iterables.getFirst(parents(), null);
      return parent != null ? parent.getTheme() : null;
    }
    return theme;
  }

  private ThemeInfo loadTheme() {
    String name = getConfig().getProject().getName();
    File dir = new File(sitePaths.themes_dir, name);
    if (!dir.exists()) {
      return ThemeInfo.INHERIT;
    } else if (!dir.isDirectory()) {
      log.warn("Bad theme for {}: not a directory", name);
      return ThemeInfo.INHERIT;
    }
    try {
      return new ThemeInfo(readFile(new File(dir, SitePaths.CSS_FILENAME)),
          readFile(new File(dir, SitePaths.HEADER_FILENAME)),
          readFile(new File(dir, SitePaths.FOOTER_FILENAME)));
    } catch (IOException e) {
      log.error("Error reading theme for " + name, e);
      return ThemeInfo.INHERIT;
    }
  }

  private String readFile(File f) throws IOException {
    return f.exists() ? Files.toString(f, UTF_8) : null;
  }

  private boolean getInheritableBoolean(Function<Project, InheritableBoolean> func) {
    for (ProjectState s : tree()) {
      switch (func.apply(s.getProject())) {
        case TRUE:
          return true;
        case FALSE:
          return false;
        case INHERIT:
        default:
          continue;
      }
    }
    return false;
  }
}