// 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.entities;

import static com.google.common.collect.ImmutableList.toImmutableList;

import com.google.auto.value.AutoValue;
import com.google.common.collect.ImmutableList;
import com.google.gerrit.common.Nullable;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.function.Consumer;

/** A single permission within an {@link AccessSection} of a project. */
@AutoValue
public abstract class Permission implements Comparable<Permission> {
  public static final String ABANDON = "abandon";
  public static final String ADD_PATCH_SET = "addPatchSet";
  public static final String CREATE = "create";
  public static final String CREATE_SIGNED_TAG = "createSignedTag";
  public static final String CREATE_TAG = "createTag";
  public static final String DELETE = "delete";
  public static final String DELETE_CHANGES = "deleteChanges";
  public static final String DELETE_OWN_CHANGES = "deleteOwnChanges";
  public static final String EDIT_ASSIGNEE = "editAssignee";
  public static final String EDIT_HASHTAGS = "editHashtags";
  public static final String EDIT_TOPIC_NAME = "editTopicName";
  public static final String FORGE_AUTHOR = "forgeAuthor";
  public static final String FORGE_COMMITTER = "forgeCommitter";
  public static final String FORGE_SERVER = "forgeServerAsCommitter";
  public static final String LABEL = "label-";
  public static final String LABEL_AS = "labelAs-";
  public static final String REMOVE_LABEL = "removeLabel-";
  public static final String OWNER = "owner";
  public static final String PUSH = "push";
  public static final String PUSH_MERGE = "pushMerge";
  public static final String READ = "read";
  public static final String REBASE = "rebase";
  public static final String REMOVE_REVIEWER = "removeReviewer";
  public static final String REVERT = "revert";
  public static final String SUBMIT = "submit";
  public static final String SUBMIT_AS = "submitAs";
  public static final String TOGGLE_WORK_IN_PROGRESS_STATE = "toggleWipState";
  public static final String VIEW_PRIVATE_CHANGES = "viewPrivateChanges";

  public static final boolean DEF_EXCLUSIVE_GROUP = false;

  private static final List<String> NAMES_LC;
  private static final int LABEL_INDEX;
  private static final int LABEL_AS_INDEX;
  private static final int REMOVE_LABEL_INDEX;

  static {
    NAMES_LC = new ArrayList<>();
    NAMES_LC.add(ABANDON.toLowerCase());
    NAMES_LC.add(ADD_PATCH_SET.toLowerCase());
    NAMES_LC.add(CREATE.toLowerCase());
    NAMES_LC.add(CREATE_SIGNED_TAG.toLowerCase());
    NAMES_LC.add(CREATE_TAG.toLowerCase());
    NAMES_LC.add(DELETE.toLowerCase());
    NAMES_LC.add(DELETE_CHANGES.toLowerCase());
    NAMES_LC.add(DELETE_OWN_CHANGES.toLowerCase());
    NAMES_LC.add(EDIT_ASSIGNEE.toLowerCase());
    NAMES_LC.add(EDIT_HASHTAGS.toLowerCase());
    NAMES_LC.add(EDIT_TOPIC_NAME.toLowerCase());
    NAMES_LC.add(FORGE_AUTHOR.toLowerCase());
    NAMES_LC.add(FORGE_COMMITTER.toLowerCase());
    NAMES_LC.add(FORGE_SERVER.toLowerCase());
    NAMES_LC.add(LABEL.toLowerCase());
    NAMES_LC.add(LABEL_AS.toLowerCase());
    NAMES_LC.add(REMOVE_LABEL.toLowerCase());
    NAMES_LC.add(OWNER.toLowerCase());
    NAMES_LC.add(PUSH.toLowerCase());
    NAMES_LC.add(PUSH_MERGE.toLowerCase());
    NAMES_LC.add(READ.toLowerCase());
    NAMES_LC.add(REBASE.toLowerCase());
    NAMES_LC.add(REMOVE_REVIEWER.toLowerCase());
    NAMES_LC.add(REVERT.toLowerCase());
    NAMES_LC.add(SUBMIT.toLowerCase());
    NAMES_LC.add(SUBMIT_AS.toLowerCase());
    NAMES_LC.add(TOGGLE_WORK_IN_PROGRESS_STATE.toLowerCase());
    NAMES_LC.add(VIEW_PRIVATE_CHANGES.toLowerCase());

    LABEL_INDEX = NAMES_LC.indexOf(Permission.LABEL);
    LABEL_AS_INDEX = NAMES_LC.indexOf(Permission.LABEL_AS.toLowerCase());
    REMOVE_LABEL_INDEX = NAMES_LC.indexOf(Permission.REMOVE_LABEL.toLowerCase());
  }

  /** Returns true if the name is recognized as a permission name. */
  public static boolean isPermission(String varName) {
    return isLabel(varName)
        || isLabelAs(varName)
        || isRemoveLabel(varName)
        || NAMES_LC.contains(varName.toLowerCase());
  }

  public static boolean hasRange(String varName) {
    return isLabel(varName) || isLabelAs(varName) || isRemoveLabel(varName);
  }

  /** Returns true if the permission name is actually for a review label. */
  public static boolean isLabel(String varName) {
    return varName.startsWith(LABEL) && LABEL.length() < varName.length();
  }

  /** Returns true if the permission is for impersonated review labels. */
  public static boolean isLabelAs(String var) {
    return var.startsWith(LABEL_AS) && LABEL_AS.length() < var.length();
  }

  /** Returns true if the permission is for impersonated review labels. */
  public static boolean isRemoveLabel(String var) {
    return var.startsWith(REMOVE_LABEL) && REMOVE_LABEL.length() < var.length();
  }

  /** Returns permission name for the given review label. */
  public static String forLabel(String labelName) {
    return LABEL + labelName;
  }

  /** Returns permission name to apply a label for another user. */
  public static String forLabelAs(String labelName) {
    return LABEL_AS + labelName;
  }

  /** Returns permission name to remove a label for another user. */
  public static String forRemoveLabel(String labelName) {
    return REMOVE_LABEL + labelName;
  }

  @Nullable
  public static String extractLabel(String varName) {
    if (isLabel(varName)) {
      return varName.substring(LABEL.length());
    } else if (isLabelAs(varName)) {
      return varName.substring(LABEL_AS.length());
    } else if (isRemoveLabel(varName)) {
      return varName.substring(REMOVE_LABEL.length());
    }
    return null;
  }

  public static boolean canBeOnAllProjects(String ref, String permissionName) {
    if (AccessSection.ALL.equals(ref)) {
      return !OWNER.equals(permissionName);
    }
    return true;
  }

  /** The permission name, eg. {@code Permission.SUBMIT} */
  public abstract String getName();

  protected abstract boolean isExclusiveGroup();

  public abstract ImmutableList<PermissionRule> getRules();

  public static Builder builder(String name) {
    return new AutoValue_Permission.Builder()
        .setName(name)
        .setExclusiveGroup(DEF_EXCLUSIVE_GROUP)
        .setRules(ImmutableList.of());
  }

  public static Permission create(String name) {
    return builder(name).build();
  }

  public String getLabel() {
    return extractLabel(getName());
  }

  public boolean getExclusiveGroup() {
    // Only permit exclusive group behavior on non OWNER permissions,
    // otherwise an owner might lose access to a delegated subspace.
    //
    return isExclusiveGroup() && !OWNER.equals(getName());
  }

  @Nullable
  public PermissionRule getRule(GroupReference group) {
    for (PermissionRule r : getRules()) {
      if (sameGroup(r, group)) {
        return r;
      }
    }

    return null;
  }

  private static boolean sameGroup(PermissionRule rule, GroupReference group) {
    if (group.getUUID() != null && rule.getGroup().getUUID() != null) {
      return group.getUUID().equals(rule.getGroup().getUUID());
    } else if (group.getName() != null && rule.getGroup().getName() != null) {
      return group.getName().equals(rule.getGroup().getName());
    } else {
      return false;
    }
  }

  @Override
  public final int compareTo(Permission b) {
    int cmp = index(this) - index(b);
    if (cmp == 0) {
      cmp = getName().compareTo(b.getName());
    }
    return cmp;
  }

  private static int index(Permission a) {
    if (isLabel(a.getName())) {
      return LABEL_INDEX;
    } else if (isLabelAs(a.getName())) {
      return LABEL_AS_INDEX;
    } else if (isRemoveLabel(a.getName())) {
      return REMOVE_LABEL_INDEX;
    }

    int index = NAMES_LC.indexOf(a.getName().toLowerCase());
    return 0 <= index ? index : NAMES_LC.size();
  }

  @Override
  public final String toString() {
    StringBuilder bldr = new StringBuilder();
    bldr.append(getName()).append(" ");
    if (isExclusiveGroup()) {
      bldr.append("[exclusive] ");
    }
    bldr.append("[");
    Iterator<PermissionRule> it = getRules().iterator();
    while (it.hasNext()) {
      bldr.append(it.next());
      if (it.hasNext()) {
        bldr.append(", ");
      }
    }
    bldr.append("]");
    return bldr.toString();
  }

  protected abstract Builder autoToBuilder();

  public Builder toBuilder() {
    Builder b = autoToBuilder();
    getRules().stream().map(PermissionRule::toBuilder).forEach(r -> b.add(r));
    return b;
  }

  @AutoValue.Builder
  public abstract static class Builder {
    private final List<PermissionRule.Builder> rulesBuilders;

    Builder() {
      rulesBuilders = new ArrayList<>();
    }

    public abstract Builder setName(String value);

    public abstract String getName();

    public abstract Builder setExclusiveGroup(boolean value);

    public Builder modifyRules(Consumer<List<PermissionRule.Builder>> modification) {
      modification.accept(rulesBuilders);
      return this;
    }

    public Builder add(PermissionRule.Builder rule) {
      return modifyRules(r -> r.add(rule));
    }

    public Builder remove(PermissionRule rule) {
      if (rule != null) {
        return removeRule(rule.getGroup());
      }
      return this;
    }

    public Builder removeRule(GroupReference group) {
      return modifyRules(rules -> rules.removeIf(rule -> sameGroup(rule.build(), group)));
    }

    public Builder clearRules() {
      return modifyRules(r -> r.clear());
    }

    public Permission build() {
      setRules(
          rulesBuilders.stream()
              .map(PermissionRule.Builder::build)
              .distinct()
              .collect(toImmutableList()));
      return autoBuild();
    }

    public List<PermissionRule.Builder> getRulesBuilders() {
      return rulesBuilders;
    }

    protected abstract ImmutableList<PermissionRule> getRules();

    protected abstract Builder setRules(ImmutableList<PermissionRule> rules);

    protected abstract Permission autoBuild();
  }
}