// Copyright (C) 2013 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.googlesource.gerrit.plugins.github.oauth;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;

import lombok.Getter;

import org.eclipse.jgit.lib.Config;

import com.google.common.base.CharMatcher;
import com.google.common.base.MoreObjects;
import com.google.common.base.Preconditions;
import com.google.common.base.Strings;
import com.google.common.collect.Maps;
import com.google.gerrit.reviewdb.client.AuthType;
import com.google.gerrit.server.config.AuthConfig;
import com.google.gerrit.server.config.CanonicalWebUrl;
import com.google.gerrit.server.config.GerritServerConfig;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import com.googlesource.gerrit.plugins.github.oauth.OAuthProtocol.Scope;

@Singleton
public
class GitHubOAuthConfig {
  public static final String CONF_SECTION = "github";
  public static final String GITHUB_OAUTH_AUTHORIZE = "/login/oauth/authorize";
  public static final String GITHUB_OAUTH_ACCESS_TOKEN =
      "/login/oauth/access_token";
  public static final String GITHUB_GET_USER = "/user";
  public static final String GERRIT_OAUTH_FINAL = "/oauth";
  public static final String GITHUB_URL_DEFAULT = "https://github.com";
  public static final String GITHUB_API_URL_DEFAULT = "https://api.github.com";
  public static final String GERRIT_LOGIN = "/login";
  public static final String GERRIT_LOGOUT = "/logout";
  public static final String GITHUB_PLUGIN_OAUTH_SCOPE = "/plugins/github-plugin/static/scope.html";

  public final String gitHubUrl;
  public final String gitHubApiUrl;
  public final String gitHubClientId;
  public final String gitHubClientSecret;
  public final String logoutRedirectUrl;
  public final String httpHeader;
  public final String gitHubOAuthUrl;
  public final String oAuthFinalRedirectUrl;
  public final String gitHubOAuthAccessTokenUrl;
  public final boolean enabled;

  @Getter
  public final Map<String, List<OAuthProtocol.Scope>> scopes;

  public final int fileUpdateMaxRetryCount;
  public final int fileUpdateMaxRetryIntervalMsec;
  public final String oauthHttpHeader;

  @Getter
  public final String scopeSelectionUrl;

  @Inject
  protected
  GitHubOAuthConfig(@GerritServerConfig Config config,
      @CanonicalWebUrl String canonicalWebUrl,
      AuthConfig authConfig) {
    httpHeader =
        Preconditions.checkNotNull(
            config.getString("auth", null, "httpHeader"),
            "HTTP Header for GitHub user must be provided");
    gitHubUrl =
        trimTrailingSlash(MoreObjects.firstNonNull(
            config.getString(CONF_SECTION, null, "url"), GITHUB_URL_DEFAULT));
    gitHubApiUrl =
        trimTrailingSlash(MoreObjects.firstNonNull(
            config.getString(CONF_SECTION, null, "apiUrl"),
            GITHUB_API_URL_DEFAULT));
    gitHubClientId =
        Preconditions.checkNotNull(
            config.getString(CONF_SECTION, null, "clientId"),
            "GitHub `clientId` must be provided");
    gitHubClientSecret =
        Preconditions.checkNotNull(
            config.getString(CONF_SECTION, null, "clientSecret"),
            "GitHub `clientSecret` must be provided");

    oauthHttpHeader = config.getString("auth", null, "httpExternalIdHeader");
    gitHubOAuthUrl = gitHubUrl + GITHUB_OAUTH_AUTHORIZE;
    gitHubOAuthAccessTokenUrl = gitHubUrl + GITHUB_OAUTH_ACCESS_TOKEN;
    logoutRedirectUrl =
        config.getString(CONF_SECTION, null, "logoutRedirectUrl");
    oAuthFinalRedirectUrl =
        trimTrailingSlash(canonicalWebUrl) + GERRIT_OAUTH_FINAL;
    scopeSelectionUrl =
        trimTrailingSlash(canonicalWebUrl)
            + MoreObjects.firstNonNull(
                config.getString(CONF_SECTION, null, "scopeSelectionUrl"),
                GITHUB_PLUGIN_OAUTH_SCOPE);

    enabled =
        config.getString("auth", null, "type").equalsIgnoreCase(
            AuthType.HTTP.toString());
    scopes = getScopes(config);

    fileUpdateMaxRetryCount =
        config.getInt(CONF_SECTION, "fileUpdateMaxRetryCount", 3);
    fileUpdateMaxRetryIntervalMsec =
        config.getInt(CONF_SECTION, "fileUpdateMaxRetryIntervalMsec", 3000);
  }

  private Map<String, List<Scope>> getScopes(Config config) {
    Map<String, List<Scope>> result = Maps.newHashMap();
    Set<String> configKeys = config.getNames(CONF_SECTION, true);
    for (String key : configKeys) {
      if (key.startsWith("scopes")) {
        String scopesString = config.getString(CONF_SECTION, null, key);
        result.put(key, parseScopesString(scopesString));
      }
    }
    return result;
  }

  private String trimTrailingSlash(String url) {
    return CharMatcher.is('/').trimTrailingFrom(url);
  }

  private List<Scope> parseScopesString(String scopesString) {
    ArrayList<Scope> result = new ArrayList<>();
    if (Strings.emptyToNull(scopesString) != null) {
      String[] scopesStrings = scopesString.split(",");
      for (String scope : scopesStrings) {
        result.add(Enum.valueOf(Scope.class, scope.trim()));
      }
    }

    return result;
  }

  public Scope[] getDefaultScopes() {
    if (scopes == null || scopes.get("scopes") == null) {
      return new Scope[0];
    } else {
      return scopes.get("scopes").toArray(new Scope[0]);
    }
  }
}