// Copyright (C) 2010 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.git;

import static com.google.gerrit.common.data.Permission.isPermission;

import com.google.common.base.CharMatcher;
import com.google.common.base.Joiner;
import com.google.common.base.Objects;
import com.google.common.base.Splitter;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import com.google.common.primitives.Shorts;
import com.google.gerrit.common.data.AccessSection;
import com.google.gerrit.common.data.ContributorAgreement;
import com.google.gerrit.common.data.GlobalCapability;
import com.google.gerrit.common.data.GroupDescription;
import com.google.gerrit.common.data.GroupReference;
import com.google.gerrit.common.data.LabelType;
import com.google.gerrit.common.data.LabelValue;
import com.google.gerrit.common.data.Permission;
import com.google.gerrit.common.data.PermissionRule;
import com.google.gerrit.common.data.PermissionRule.Action;
import com.google.gerrit.common.data.RefConfigSection;
import com.google.gerrit.reviewdb.client.AccountGroup;
import com.google.gerrit.reviewdb.client.AccountProjectWatch.NotifyType;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.reviewdb.client.Project.State;
import com.google.gerrit.reviewdb.client.Project.SubmitType;
import com.google.gerrit.server.account.GroupBackend;
import com.google.gerrit.server.config.ConfigUtil;
import com.google.gerrit.server.mail.Address;

import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.lib.CommitBuilder;
import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.util.StringUtils;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class ProjectConfig extends VersionedMetaData {
  private static final String PROJECT_CONFIG = "project.config";
  private static final String GROUP_LIST = "groups";

  private static final String PROJECT = "project";
  private static final String KEY_DESCRIPTION = "description";

  private static final String ACCESS = "access";
  private static final String KEY_INHERIT_FROM = "inheritFrom";
  private static final String KEY_GROUP_PERMISSIONS = "exclusiveGroupPermissions";

  private static final String ACCOUNTS = "accounts";
  private static final String KEY_SAME_GROUP_VISIBILITY = "sameGroupVisibility";

  private static final String CONTRIBUTOR_AGREEMENT = "contributor-agreement";
  private static final String KEY_ACCEPTED = "accepted";
  private static final String KEY_REQUIRE_CONTACT_INFORMATION = "requireContactInformation";
  private static final String KEY_AUTO_VERIFY = "autoVerify";
  private static final String KEY_AGREEMENT_URL = "agreementUrl";

  private static final String NOTIFY = "notify";
  private static final String KEY_EMAIL = "email";
  private static final String KEY_FILTER = "filter";
  private static final String KEY_TYPE = "type";
  private static final String KEY_HEADER = "header";

  private static final String CAPABILITY = "capability";

  private static final String RECEIVE = "receive";
  private static final String KEY_REQUIRE_SIGNED_OFF_BY = "requireSignedOffBy";
  private static final String KEY_REQUIRE_CHANGE_ID = "requireChangeId";
  private static final String KEY_REQUIRE_CONTRIBUTOR_AGREEMENT =
      "requireContributorAgreement";

  private static final String SUBMIT = "submit";
  private static final String KEY_ACTION = "action";
  private static final String KEY_MERGE_CONTENT = "mergeContent";
  private static final String KEY_STATE = "state";

  private static final String DASHBOARD = "dashboard";
  private static final String KEY_DEFAULT = "default";
  private static final String KEY_LOCAL_DEFAULT = "local-default";

  private static final String LABEL = "label";
  private static final String KEY_ABBREVIATION = "abbreviation";
  private static final String KEY_FUNCTION = "function";
  private static final String KEY_COPY_MIN_SCORE = "copyMinScore";
  private static final String KEY_VALUE = "value";
  private static final String KEY_CAN_OVERRIDE = "canOverride";
  private static final Set<String> LABEL_FUNCTIONS = ImmutableSet.of(
      "MaxWithBlock", "MaxNoBlock", "NoBlock", "NoOp");

  private static final SubmitType defaultSubmitAction =
      SubmitType.MERGE_IF_NECESSARY;
  private static final State defaultStateValue =
      State.ACTIVE;

  private Project.NameKey projectName;
  private Project project;
  private AccountsSection accountsSection;
  private Map<AccountGroup.UUID, GroupReference> groupsByUUID;
  private Map<String, AccessSection> accessSections;
  private Map<String, ContributorAgreement> contributorAgreements;
  private Map<String, NotifyConfig> notifySections;
  private Map<String, LabelType> labelSections;
  private List<ValidationError> validationErrors;
  private ObjectId rulesId;

  public static ProjectConfig read(MetaDataUpdate update) throws IOException,
      ConfigInvalidException {
    ProjectConfig r = new ProjectConfig(update.getProjectName());
    r.load(update);
    return r;
  }

  public static ProjectConfig read(MetaDataUpdate update, ObjectId id)
      throws IOException, ConfigInvalidException {
    ProjectConfig r = new ProjectConfig(update.getProjectName());
    r.load(update, id);
    return r;
  }

  public ProjectConfig(Project.NameKey projectName) {
    this.projectName = projectName;
  }

  public Project getProject() {
    return project;
  }

  public AccountsSection getAccountsSection() {
    return accountsSection;
  }

  public AccessSection getAccessSection(String name) {
    return getAccessSection(name, false);
  }

  public AccessSection getAccessSection(String name, boolean create) {
    AccessSection as = accessSections.get(name);
    if (as == null && create) {
      as = new AccessSection(name);
      accessSections.put(name, as);
    }
    return as;
  }

  public Collection<AccessSection> getAccessSections() {
    return sort(accessSections.values());
  }

  public void remove(AccessSection section) {
    if (section != null) {
      accessSections.remove(section.getName());
    }
  }

  public void replace(AccessSection section) {
    for (Permission permission : section.getPermissions()) {
      for (PermissionRule rule : permission.getRules()) {
        rule.setGroup(resolve(rule.getGroup()));
      }
    }

    accessSections.put(section.getName(), section);
  }

  public ContributorAgreement getContributorAgreement(String name) {
    return getContributorAgreement(name, false);
  }

  public ContributorAgreement getContributorAgreement(String name, boolean create) {
    ContributorAgreement ca = contributorAgreements.get(name);
    if (ca == null && create) {
      ca = new ContributorAgreement(name);
      contributorAgreements.put(name, ca);
    }
    return ca;
  }

  public Collection<ContributorAgreement> getContributorAgreements() {
    return sort(contributorAgreements.values());
  }

  public void remove(ContributorAgreement section) {
    if (section != null) {
      accessSections.remove(section.getName());
    }
  }

  public void replace(ContributorAgreement section) {
    section.setAutoVerify(resolve(section.getAutoVerify()));
    for (PermissionRule rule : section.getAccepted()) {
      rule.setGroup(resolve(rule.getGroup()));
    }

    contributorAgreements.put(section.getName(), section);
  }

  public Collection<NotifyConfig> getNotifyConfigs() {
    return notifySections.values();
  }

  public Map<String, LabelType> getLabelSections() {
    return labelSections;
  }

  public GroupReference resolve(AccountGroup group) {
    return resolve(GroupReference.forGroup(group));
  }

  public GroupReference resolve(GroupReference group) {
    if (group != null) {
      GroupReference ref = groupsByUUID.get(group.getUUID());
      if (ref != null) {
        return ref;
      }
      groupsByUUID.put(group.getUUID(), group);
    }
    return group;
  }

  /** @return the group reference, if the group is used by at least one rule. */
  public GroupReference getGroup(AccountGroup.UUID uuid) {
    return groupsByUUID.get(uuid);
  }

  /** @return set of all groups used by this configuration. */
  public Set<AccountGroup.UUID> getAllGroupUUIDs() {
    return Collections.unmodifiableSet(groupsByUUID.keySet());
  }

  /**
   * @return the project's rules.pl ObjectId, if present in the branch.
   *    Null if it doesn't exist.
   */
  public ObjectId getRulesId() {
    return rulesId;
  }

  /**
   * Check all GroupReferences use current group name, repairing stale ones.
   *
   * @param groupBackend cache to use when looking up group information by UUID.
   * @return true if one or more group names was stale.
   */
  public boolean updateGroupNames(GroupBackend groupBackend) {
    boolean dirty = false;
    for (GroupReference ref : groupsByUUID.values()) {
      GroupDescription.Basic g = groupBackend.get(ref.getUUID());
      if (g != null && !g.getName().equals(ref.getName())) {
        dirty = true;
        ref.setName(g.getName());
      }
    }
    return dirty;
  }

  /**
   * Get the validation errors, if any were discovered during load.
   *
   * @return list of errors; empty list if there are no errors.
   */
  public List<ValidationError> getValidationErrors() {
    if (validationErrors != null) {
      return Collections.unmodifiableList(validationErrors);
    } else {
      return Collections.emptyList();
    }
  }

  @Override
  protected String getRefName() {
    return GitRepositoryManager.REF_CONFIG;
  }

  @Override
  protected void onLoad() throws IOException, ConfigInvalidException {
    Map<String, GroupReference> groupsByName = readGroupList();

    rulesId = getObjectId("rules.pl");
    Config rc = readConfig(PROJECT_CONFIG);
    project = new Project(projectName);

    Project p = project;
    p.setDescription(rc.getString(PROJECT, null, KEY_DESCRIPTION));
    if (p.getDescription() == null) {
      p.setDescription("");
    }
    p.setParentName(rc.getString(ACCESS, null, KEY_INHERIT_FROM));

    p.setUseContributorAgreements(getEnum(rc, RECEIVE, null, KEY_REQUIRE_CONTRIBUTOR_AGREEMENT, Project.InheritableBoolean.INHERIT));
    p.setUseSignedOffBy(getEnum(rc, RECEIVE, null, KEY_REQUIRE_SIGNED_OFF_BY, Project.InheritableBoolean.INHERIT));
    p.setRequireChangeID(getEnum(rc, RECEIVE, null, KEY_REQUIRE_CHANGE_ID, Project.InheritableBoolean.INHERIT));

    p.setSubmitType(getEnum(rc, SUBMIT, null, KEY_ACTION, defaultSubmitAction));
    p.setUseContentMerge(getEnum(rc, SUBMIT, null, KEY_MERGE_CONTENT, Project.InheritableBoolean.INHERIT));
    p.setState(getEnum(rc, PROJECT, null, KEY_STATE, defaultStateValue));

    p.setDefaultDashboard(rc.getString(DASHBOARD, null, KEY_DEFAULT));
    p.setLocalDefaultDashboard(rc.getString(DASHBOARD, null, KEY_LOCAL_DEFAULT));

    loadAccountsSection(rc, groupsByName);
    loadContributorAgreements(rc, groupsByName);
    loadAccessSections(rc, groupsByName);
    loadNotifySections(rc, groupsByName);
    loadLabelSections(rc);
  }

  private void loadAccountsSection(
      Config rc, Map<String, GroupReference> groupsByName) {
    accountsSection = new AccountsSection();
    accountsSection.setSameGroupVisibility(loadPermissionRules(
        rc, ACCOUNTS, null, KEY_SAME_GROUP_VISIBILITY, groupsByName, false));
  }

  private void loadContributorAgreements(
      Config rc, Map<String, GroupReference> groupsByName) {
    contributorAgreements = new HashMap<String, ContributorAgreement>();
    for (String name : rc.getSubsections(CONTRIBUTOR_AGREEMENT)) {
      ContributorAgreement ca = getContributorAgreement(name, true);
      ca.setDescription(rc.getString(CONTRIBUTOR_AGREEMENT, name, KEY_DESCRIPTION));
      ca.setRequireContactInformation(
          rc.getBoolean(CONTRIBUTOR_AGREEMENT, name, KEY_REQUIRE_CONTACT_INFORMATION, false));
      ca.setAgreementUrl(rc.getString(CONTRIBUTOR_AGREEMENT, name, KEY_AGREEMENT_URL));
      ca.setAccepted(loadPermissionRules(
          rc, CONTRIBUTOR_AGREEMENT, name, KEY_ACCEPTED, groupsByName, false));

      List<PermissionRule> rules = loadPermissionRules(
          rc, CONTRIBUTOR_AGREEMENT, name, KEY_AUTO_VERIFY, groupsByName, false);
      if (rules.isEmpty()) {
        ca.setAutoVerify(null);
      } else if (rules.size() > 1) {
        error(new ValidationError(PROJECT_CONFIG, "Invalid rule in "
            + CONTRIBUTOR_AGREEMENT
            + "." + name
            + "." + KEY_AUTO_VERIFY
            + ": at most one group may be set"));
      } else if (rules.get(0).getAction() != Action.ALLOW) {
        error(new ValidationError(PROJECT_CONFIG, "Invalid rule in "
            + CONTRIBUTOR_AGREEMENT
            + "." + name
            + "." + KEY_AUTO_VERIFY
            + ": the group must be allowed"));
      } else {
        ca.setAutoVerify(rules.get(0).getGroup());
      }
    }
  }

  /**
   * Parses the [notify] sections out of the configuration file.
   *
   * <pre>
   *   [notify "reviewers"]
   *     email = group Reviewers
   *     type = new_changes
   *
   *   [notify "dev-team"]
   *     email = dev-team@example.com
   *     filter = branch:master
   *
   *   [notify "qa"]
   *     email = qa@example.com
   *     filter = branch:\"^(maint|stable)-.*\"
   *     type = submitted_changes
   * </pre>
   */
  private void loadNotifySections(
      Config rc, Map<String, GroupReference> groupsByName) {
    notifySections = Maps.newHashMap();
    for (String sectionName : rc.getSubsections(NOTIFY)) {
      NotifyConfig n = new NotifyConfig();
      n.setName(sectionName);
      n.setFilter(rc.getString(NOTIFY, sectionName, KEY_FILTER));

      EnumSet<NotifyType> types = EnumSet.noneOf(NotifyType.class);
      types.addAll(ConfigUtil.getEnumList(rc,
          NOTIFY, sectionName, KEY_TYPE,
          NotifyType.ALL));
      n.setTypes(types);
      n.setHeader(ConfigUtil.getEnum(rc,
          NOTIFY, sectionName, KEY_HEADER,
          NotifyConfig.Header.BCC));

      for (String dst : rc.getStringList(NOTIFY, sectionName, KEY_EMAIL)) {
        if (dst.startsWith("group ")) {
          String groupName = dst.substring(6).trim();
          GroupReference ref = groupsByName.get(groupName);
          if (ref == null) {
            ref = new GroupReference(null, groupName);
            groupsByName.put(ref.getName(), ref);
          }
          if (ref.getUUID() != null) {
            n.addEmail(ref);
          } else {
            error(new ValidationError(PROJECT_CONFIG,
                "group \"" + ref.getName() + "\" not in " + GROUP_LIST));
          }
        } else if (dst.startsWith("user ")) {
          error(new ValidationError(PROJECT_CONFIG, dst + " not supported"));
        } else {
          try {
            n.addEmail(Address.parse(dst));
          } catch (IllegalArgumentException err) {
            error(new ValidationError(PROJECT_CONFIG,
                "notify section \"" + sectionName + "\" has invalid email \"" + dst + "\""));
          }
        }
      }
      notifySections.put(sectionName, n);
    }
  }

  private void loadAccessSections(
      Config rc, Map<String, GroupReference> groupsByName) {
    accessSections = new HashMap<String, AccessSection>();
    for (String refName : rc.getSubsections(ACCESS)) {
      if (RefConfigSection.isValid(refName)) {
        AccessSection as = getAccessSection(refName, true);

        for (String varName : rc.getStringList(ACCESS, refName, KEY_GROUP_PERMISSIONS)) {
          for (String n : varName.split("[, \t]{1,}")) {
            if (isPermission(n)) {
              as.getPermission(n, true).setExclusiveGroup(true);
            }
          }
        }

        for (String varName : rc.getNames(ACCESS, refName)) {
          if (isPermission(varName)) {
            Permission perm = as.getPermission(varName, true);
            loadPermissionRules(rc, ACCESS, refName, varName, groupsByName,
                perm, perm.isLabel());
          }
        }
      }
    }

    AccessSection capability = null;
    for (String varName : rc.getNames(CAPABILITY)) {
      if (GlobalCapability.isCapability(varName)) {
        if (capability == null) {
          capability = new AccessSection(AccessSection.GLOBAL_CAPABILITIES);
          accessSections.put(AccessSection.GLOBAL_CAPABILITIES, capability);
        }
        Permission perm = capability.getPermission(varName, true);
        loadPermissionRules(rc, CAPABILITY, null, varName, groupsByName, perm,
            GlobalCapability.hasRange(varName));
      }
    }
  }

  private List<PermissionRule> loadPermissionRules(Config rc, String section,
      String subsection, String varName,
      Map<String, GroupReference> groupsByName,
      boolean useRange) {
    Permission perm = new Permission(varName);
    loadPermissionRules(rc, section, subsection, varName, groupsByName, perm, useRange);
    return perm.getRules();
  }

  private void loadPermissionRules(Config rc, String section,
      String subsection, String varName,
      Map<String, GroupReference> groupsByName, Permission perm,
      boolean useRange) {
    for (String ruleString : rc.getStringList(section, subsection, varName)) {
      PermissionRule rule;
      try {
        rule = PermissionRule.fromString(ruleString, useRange);
      } catch (IllegalArgumentException notRule) {
        error(new ValidationError(PROJECT_CONFIG, "Invalid rule in "
            + section
            + (subsection != null ? "." + subsection : "")
            + "." + varName + ": "
            + notRule.getMessage()));
        continue;
      }

      GroupReference ref = groupsByName.get(rule.getGroup().getName());
      if (ref == null) {
        // The group wasn't mentioned in the groups table, so there is
        // no valid UUID for it. Pool the reference anyway so at least
        // all rules in the same file share the same GroupReference.
        //
        ref = rule.getGroup();
        groupsByName.put(ref.getName(), ref);
        error(new ValidationError(PROJECT_CONFIG,
            "group \"" + ref.getName() + "\" not in " + GROUP_LIST));
      }

      rule.setGroup(ref);
      perm.add(rule);
    }
  }

  private static LabelValue parseLabelValue(String src) {
    List<String> parts = ImmutableList.copyOf(
        Splitter.on(CharMatcher.WHITESPACE).omitEmptyStrings().limit(2)
        .split(src));
    if (parts.isEmpty()) {
      throw new IllegalArgumentException("empty value");
    }
    String valueText = parts.size() > 1 ? parts.get(1) : "";
    return new LabelValue(
        Shorts.checkedCast(PermissionRule.parseInt(parts.get(0))),
        valueText);
  }

  private void loadLabelSections(Config rc) throws IOException {
    Map<String, String> lowerNames = Maps.newHashMapWithExpectedSize(2);
    labelSections = Maps.newLinkedHashMap();
    for (String name : rc.getSubsections(LABEL)) {
      String lower = name.toLowerCase();
      if (lowerNames.containsKey(lower)) {
        error(new ValidationError(PROJECT_CONFIG, String.format(
            "Label \"%s\" conflicts with \"%s\"",
            name, lowerNames.get(lower))));
      }
      lowerNames.put(lower, name);

      List<LabelValue> values = Lists.newArrayList();
      for (String value : rc.getStringList(LABEL, name, KEY_VALUE)) {
        try {
          values.add(parseLabelValue(value));
        } catch (IllegalArgumentException notValue) {
          error(new ValidationError(PROJECT_CONFIG, String.format(
              "Invalid %s \"%s\" for label \"%s\": %s",
              KEY_VALUE, value, name, notValue.getMessage())));
        }
      }

      LabelType label;
      try {
        label = new LabelType(name, values);
      } catch (IllegalArgumentException badName) {
        error(new ValidationError(PROJECT_CONFIG, String.format(
            "Invalid label \"%s\"", name)));
        continue;
      }
      String abbr = rc.getString(LABEL, name, KEY_ABBREVIATION);
      if (abbr != null) {
        label.setAbbreviation(abbr);
      }

      String functionName = Objects.firstNonNull(
          rc.getString(LABEL, name, KEY_FUNCTION), "MaxWithBlock");
      if (LABEL_FUNCTIONS.contains(functionName)) {
        label.setFunctionName(functionName);
      } else {
        error(new ValidationError(PROJECT_CONFIG, String.format(
            "Invalid %s for label \"%s\". Valid names are: %s",
            KEY_FUNCTION, name, Joiner.on(", ").join(LABEL_FUNCTIONS))));
        label.setFunctionName(null);
      }
      label.setCopyMinScore(
          rc.getBoolean(LABEL, name, KEY_COPY_MIN_SCORE, false));
      label.setCanOverride(
          rc.getBoolean(LABEL, name, KEY_CAN_OVERRIDE, true));
      labelSections.put(name, label);
    }
  }

  private Map<String, GroupReference> readGroupList() throws IOException {
    groupsByUUID = new HashMap<AccountGroup.UUID, GroupReference>();
    Map<String, GroupReference> groupsByName =
        new HashMap<String, GroupReference>();

    BufferedReader br = new BufferedReader(new StringReader(readUTF8(GROUP_LIST)));
    String s;
    for (int lineNumber = 1; (s = br.readLine()) != null; lineNumber++) {
      if (s.isEmpty() || s.startsWith("#")) {
        continue;
      }

      int tab = s.indexOf('\t');
      if (tab < 0) {
        error(new ValidationError(GROUP_LIST, lineNumber, "missing tab delimiter"));
        continue;
      }

      AccountGroup.UUID uuid = new AccountGroup.UUID(s.substring(0, tab).trim());
      String name = s.substring(tab + 1).trim();
      GroupReference ref = new GroupReference(uuid, name);

      groupsByUUID.put(uuid, ref);
      groupsByName.put(name, ref);
    }
    return groupsByName;
  }

  @Override
  protected void onSave(CommitBuilder commit) throws IOException,
      ConfigInvalidException {
    if (commit.getMessage() == null || "".equals(commit.getMessage())) {
      commit.setMessage("Updated project configuration\n");
    }

    Config rc = readConfig(PROJECT_CONFIG);
    Project p = project;

    if (p.getDescription() != null && !p.getDescription().isEmpty()) {
      rc.setString(PROJECT, null, KEY_DESCRIPTION, p.getDescription());
    } else {
      rc.unset(PROJECT, null, KEY_DESCRIPTION);
    }
    set(rc, ACCESS, null, KEY_INHERIT_FROM, p.getParentName());

    set(rc, RECEIVE, null, KEY_REQUIRE_CONTRIBUTOR_AGREEMENT, p.getUseContributorAgreements(), Project.InheritableBoolean.INHERIT);
    set(rc, RECEIVE, null, KEY_REQUIRE_SIGNED_OFF_BY, p.getUseSignedOffBy(), Project.InheritableBoolean.INHERIT);
    set(rc, RECEIVE, null, KEY_REQUIRE_CHANGE_ID, p.getRequireChangeID(), Project.InheritableBoolean.INHERIT);

    set(rc, SUBMIT, null, KEY_ACTION, p.getSubmitType(), defaultSubmitAction);
    set(rc, SUBMIT, null, KEY_MERGE_CONTENT, p.getUseContentMerge(), Project.InheritableBoolean.INHERIT);

    set(rc, PROJECT, null, KEY_STATE, p.getState(), null);

    set(rc, DASHBOARD, null, KEY_DEFAULT, p.getDefaultDashboard());
    set(rc, DASHBOARD, null, KEY_LOCAL_DEFAULT, p.getLocalDefaultDashboard());

    Set<AccountGroup.UUID> keepGroups = new HashSet<AccountGroup.UUID>();
    saveAccountsSection(rc, keepGroups);
    saveContributorAgreements(rc, keepGroups);
    saveAccessSections(rc, keepGroups);
    saveNotifySections(rc, keepGroups);
    groupsByUUID.keySet().retainAll(keepGroups);
    saveLabelSections(rc);

    saveConfig(PROJECT_CONFIG, rc);
    saveGroupList();
  }

  private void saveAccountsSection(Config rc, Set<AccountGroup.UUID> keepGroups) {
    if (accountsSection != null) {
      rc.setStringList(ACCOUNTS, null, KEY_SAME_GROUP_VISIBILITY,
          ruleToStringList(accountsSection.getSameGroupVisibility(), keepGroups));
    }
  }

  private void saveContributorAgreements(
      Config rc, Set<AccountGroup.UUID> keepGroups) {
    for (ContributorAgreement ca : sort(contributorAgreements.values())) {
      set(rc, CONTRIBUTOR_AGREEMENT, ca.getName(), KEY_DESCRIPTION, ca.getDescription());
      set(rc, CONTRIBUTOR_AGREEMENT, ca.getName(), KEY_REQUIRE_CONTACT_INFORMATION, ca.isRequireContactInformation());
      set(rc, CONTRIBUTOR_AGREEMENT, ca.getName(), KEY_AGREEMENT_URL, ca.getAgreementUrl());

      if (ca.getAutoVerify() != null) {
        if (ca.getAutoVerify().getUUID() != null) {
          keepGroups.add(ca.getAutoVerify().getUUID());
        }
        String autoVerify = new PermissionRule(ca.getAutoVerify()).asString(false);
        set(rc, CONTRIBUTOR_AGREEMENT, ca.getName(), KEY_AUTO_VERIFY, autoVerify);
      } else {
        rc.unset(CONTRIBUTOR_AGREEMENT, ca.getName(), KEY_AUTO_VERIFY);
      }

      rc.setStringList(CONTRIBUTOR_AGREEMENT, ca.getName(), KEY_ACCEPTED,
          ruleToStringList(ca.getAccepted(), keepGroups));
    }
  }

  private void saveNotifySections(
      Config rc, Set<AccountGroup.UUID> keepGroups) {
    for (NotifyConfig nc : sort(notifySections.values())) {
      List<String> email = Lists.newArrayList();
      for (GroupReference gr : nc.getGroups()) {
        if (gr.getUUID() != null) {
          keepGroups.add(gr.getUUID());
        }
        email.add(new PermissionRule(gr).asString(false));
      }
      Collections.sort(email);

      List<String> addrs = Lists.newArrayList();
      for (Address addr : nc.getAddresses()) {
        addrs.add(addr.toString());
      }
      Collections.sort(addrs);
      email.addAll(addrs);

      set(rc, NOTIFY, nc.getName(), KEY_HEADER,
          nc.getHeader(), NotifyConfig.Header.BCC);
      if (email.isEmpty()) {
        rc.unset(NOTIFY, nc.getName(), KEY_EMAIL);
      } else {
        rc.setStringList(NOTIFY, nc.getName(), KEY_EMAIL, email);
      }

      if (nc.getNotify().equals(EnumSet.of(NotifyType.ALL))) {
        rc.unset(NOTIFY, nc.getName(), KEY_TYPE);
      } else {
        List<String> types = Lists.newArrayListWithCapacity(4);
        for (NotifyType t : NotifyType.values()) {
          if (nc.isNotify(t)) {
            types.add(StringUtils.toLowerCase(t.name()));
          }
        }
        rc.setStringList(NOTIFY, nc.getName(), KEY_TYPE, types);
      }

      set(rc, NOTIFY, nc.getName(), KEY_FILTER, nc.getFilter());
    }
  }

  private List<String> ruleToStringList(
      List<PermissionRule> list, Set<AccountGroup.UUID> keepGroups) {
    List<String> rules = new ArrayList<String>();
    for (PermissionRule rule : sort(list)) {
      if (rule.getGroup().getUUID() != null) {
        keepGroups.add(rule.getGroup().getUUID());
      }
      rules.add(rule.asString(false));
    }
    return rules;
  }

  private void saveAccessSections(
      Config rc, Set<AccountGroup.UUID> keepGroups) {
    AccessSection capability = accessSections.get(AccessSection.GLOBAL_CAPABILITIES);
    if (capability != null) {
      Set<String> have = new HashSet<String>();
      for (Permission permission : sort(capability.getPermissions())) {
        have.add(permission.getName().toLowerCase());

        boolean needRange = GlobalCapability.hasRange(permission.getName());
        List<String> rules = new ArrayList<String>();
        for (PermissionRule rule : sort(permission.getRules())) {
          GroupReference group = rule.getGroup();
          if (group.getUUID() != null) {
            keepGroups.add(group.getUUID());
          }
          rules.add(rule.asString(needRange));
        }
        rc.setStringList(CAPABILITY, null, permission.getName(), rules);
      }
      for (String varName : rc.getNames(CAPABILITY)) {
        if (GlobalCapability.isCapability(varName)
            && !have.contains(varName.toLowerCase())) {
          rc.unset(CAPABILITY, null, varName);
        }
      }
    } else {
      rc.unsetSection(CAPABILITY, null);
    }

    for (AccessSection as : sort(accessSections.values())) {
      String refName = as.getName();
      if (AccessSection.GLOBAL_CAPABILITIES.equals(refName)) {
        continue;
      }

      StringBuilder doNotInherit = new StringBuilder();
      for (Permission perm : sort(as.getPermissions())) {
        if (perm.getExclusiveGroup()) {
          if (0 < doNotInherit.length()) {
            doNotInherit.append(' ');
          }
          doNotInherit.append(perm.getName());
        }
      }
      if (0 < doNotInherit.length()) {
        rc.setString(ACCESS, refName, KEY_GROUP_PERMISSIONS, doNotInherit.toString());
      } else {
        rc.unset(ACCESS, refName, KEY_GROUP_PERMISSIONS);
      }

      Set<String> have = new HashSet<String>();
      for (Permission permission : sort(as.getPermissions())) {
        have.add(permission.getName().toLowerCase());

        boolean needRange = permission.isLabel();
        List<String> rules = new ArrayList<String>();
        for (PermissionRule rule : sort(permission.getRules())) {
          GroupReference group = rule.getGroup();
          if (group.getUUID() != null) {
            keepGroups.add(group.getUUID());
          }
          rules.add(rule.asString(needRange));
        }
        rc.setStringList(ACCESS, refName, permission.getName(), rules);
      }

      for (String varName : rc.getNames(ACCESS, refName)) {
        if (isPermission(varName) && !have.contains(varName.toLowerCase())) {
          rc.unset(ACCESS, refName, varName);
        }
      }
    }

    for (String name : rc.getSubsections(ACCESS)) {
      if (RefConfigSection.isValid(name) && !accessSections.containsKey(name)) {
        rc.unsetSection(ACCESS, name);
      }
    }
  }

  private void saveLabelSections(Config rc) {
    List<String> existing = Lists.newArrayList(rc.getSubsections(LABEL));
    if (!Lists.newArrayList(labelSections.keySet()).equals(existing)) {
      // Order of sections changed, remove and rewrite them all.
      for (String name : existing) {
        rc.unsetSection(LABEL, name);
      }
    }

    Set<String> toUnset = Sets.newHashSet(existing);
    for (Map.Entry<String, LabelType> e : labelSections.entrySet()) {
      String name = e.getKey();
      LabelType label = e.getValue();
      toUnset.remove(name);
      rc.setString(LABEL, name, KEY_FUNCTION, label.getFunctionName());

      if (!LabelType.defaultAbbreviation(name)
          .equals(label.getAbbreviation())) {
        rc.setString(
            LABEL, name, KEY_ABBREVIATION, label.getAbbreviation());
      } else {
        rc.unset(LABEL, name, KEY_ABBREVIATION);
      }
      if (label.isCopyMinScore()) {
        rc.setBoolean(LABEL, name, KEY_COPY_MIN_SCORE, true);
      } else {
        rc.unset(LABEL, name, KEY_COPY_MIN_SCORE);
      }
      if (!label.canOverride()) {
        rc.setBoolean(LABEL, name, KEY_CAN_OVERRIDE, false);
      } else {
        rc.unset(LABEL, name, KEY_CAN_OVERRIDE);
      }

      List<String> values =
          Lists.newArrayListWithCapacity(label.getValues().size());
      for (LabelValue value : label.getValues()) {
        values.add(value.format());
      }
      rc.setStringList(LABEL, name, KEY_VALUE, values);
    }

    for (String name : toUnset) {
      rc.unsetSection(LABEL, name);
    }
  }

  private void saveGroupList() throws IOException {
    if (groupsByUUID.isEmpty()) {
      saveFile(GROUP_LIST, null);
      return;
    }

    final int uuidLen = 40;
    StringBuilder buf = new StringBuilder();
    buf.append(pad(uuidLen, "# UUID"));
    buf.append('\t');
    buf.append("Group Name");
    buf.append('\n');

    buf.append('#');
    buf.append('\n');

    for (GroupReference g : sort(groupsByUUID.values())) {
      if (g.getUUID() != null && g.getName() != null) {
        buf.append(pad(uuidLen, g.getUUID().get()));
        buf.append('\t');
        buf.append(g.getName());
        buf.append('\n');
      }
    }
    saveUTF8(GROUP_LIST, buf.toString());
  }

  private <E extends Enum<?>> E getEnum(Config rc, String section,
      String subsection, String name, E defaultValue) {
    try {
      return rc.getEnum(section, subsection, name, defaultValue);
    } catch (IllegalArgumentException err) {
      error(new ValidationError(PROJECT_CONFIG, err.getMessage()));
      return defaultValue;
    }
  }

  private void error(ValidationError error) {
    if (validationErrors == null) {
      validationErrors = new ArrayList<ValidationError>(4);
    }
    validationErrors.add(error);
  }

  private static String pad(int len, String src) {
    if (len <= src.length()) {
      return src;
    }

    StringBuilder r = new StringBuilder(len);
    r.append(src);
    while (r.length() < len) {
      r.append(' ');
    }
    return r.toString();
  }

  private static <T extends Comparable<? super T>> List<T> sort(Collection<T> m) {
    ArrayList<T> r = new ArrayList<T>(m);
    Collections.sort(r);
    return r;
  }
}