Introduce MessageListContext.

This will encapsulate meta information about a message list. Notably the
mailbox it's showing OR the search parameters that were used to build
its contents.

Change-Id: Ibe078a700860e7b9426c865e843e899f82306a96

src/com/android/email/MessageListContext.java

@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2011 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.android.email;
+
+import android.content.Context;
+import android.content.Intent;
+
+import com.android.email.activity.EmailActivity;
+import com.android.emailcommon.provider.Account;
+import com.android.emailcommon.provider.Mailbox;
+import com.android.emailcommon.service.SearchParams;
+import com.google.common.base.Preconditions;
+
+/**
+ * Information about what is being shown in a message list.
+ * This encapsulates the meta-data about the list of messages, which can either be the
+ * {@link Mailbox} ID, or {@link SearchParams}.
+ */
+public class MessageListContext {
+
+    /**
+     * The active account. Changing an account is a destructive enough operation that it warrants
+     * the creation of a new {@link MessageListContext}
+     */
+    public final long mAccountId;
+
+    /**
+     * The mailbox ID containing the messages. Must not be {@link Mailbox#NO_MAILBOX}.
+     */
+    private final long mMailboxId;
+
+    /**
+     * The search parameters, if the user is in a search.
+     * If non-null, {@link #mMailboxId} will always correspond to the search mailbox for the user.
+     */
+    private final SearchParams mSearchParams;
+
+    // Private constructor - use static builder methods to generate a validated instance.
+    private MessageListContext(long accountId, long searchMailboxId, SearchParams searchParams) {
+        mAccountId = accountId;
+        mMailboxId = searchMailboxId;
+        mSearchParams = searchParams;
+    }
+
+    /**
+     * Builds an instance from the information provided in an Intent.
+     * This method will perform proper validation and throw an {@link IllegalArgumentException}
+     * if values in the {@link Intent} are inconsistent.
+     * This will also handle the generation of default values if certain fields are unspecified
+     * in the {@link Intent}.
+     */
+    public static MessageListContext forIntent(Context context, Intent intent) {
+        long accountId = intent.getLongExtra(EmailActivity.EXTRA_ACCOUNT_ID, Account.NO_ACCOUNT);
+        long mailboxId = intent.getLongExtra(EmailActivity.EXTRA_MAILBOX_ID, Mailbox.NO_MAILBOX);
+
+        if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
+            final String queryTerm = intent.getStringExtra(EmailActivity.EXTRA_QUERY_STRING);
+            final long searchMailboxId =
+                    Controller.getInstance(context).getSearchMailbox(accountId).mId;
+            return forSearch(accountId, searchMailboxId, new SearchParams(mailboxId, queryTerm));
+        } else {
+            if (accountId == Account.NO_ACCOUNT) {
+                accountId = Account.getDefaultAccountId(context);
+            }
+            if (mailboxId == Mailbox.NO_MAILBOX) {
+                mailboxId = (accountId == Account.ACCOUNT_ID_COMBINED_VIEW)
+                        ? Mailbox.QUERY_ALL_INBOXES
+                        : Mailbox.findMailboxOfType(context, accountId, Mailbox.TYPE_INBOX);
+            }
+
+            return forMailbox(accountId, mailboxId);
+        }
+    }
+
+    /**
+     * Creates a view context for a given search.
+     */
+    public static MessageListContext forSearch(
+            long accountId, long searchMailboxId, SearchParams searchParams) {
+        Preconditions.checkArgument(
+                Account.isNormalAccount(accountId),
+                "Can only search in normal accounts");
+        return new MessageListContext(accountId, searchMailboxId, searchParams);
+    }
+
+    /**
+     * Creates a view context for a given mailbox.
+     */
+    public static MessageListContext forMailbox(long accountId, long mailboxId) {
+        Preconditions.checkArgument(accountId != Account.NO_ACCOUNT, "Must specify an account");
+        Preconditions.checkArgument(mailboxId != Mailbox.NO_MAILBOX, "Must specify a mailbox");
+        return new MessageListContext(accountId, mailboxId, null);
+    }
+
+    public boolean isSearch() {
+        return mSearchParams != null;
+    }
+
+    public long getSearchedMailbox() {
+        return isSearch() ? mSearchParams.mMailboxId : Mailbox.NO_MAILBOX;
+    }
+
+    public SearchParams getSearchParams() {
+        return mSearchParams;
+    }
+
+    public long getMailboxId() {
+        return mMailboxId;
+    }
+}

src/com/android/email/activity/EmailActivity.java

@@ -57,10 +57,10 @@ import java.util.ArrayList;
  * the UIController.
  */
 public class EmailActivity extends Activity implements View.OnClickListener, FragmentInstallable {
-    private static final String EXTRA_ACCOUNT_ID = "ACCOUNT_ID";
-    private static final String EXTRA_MAILBOX_ID = "MAILBOX_ID";
-    private static final String EXTRA_MESSAGE_ID = "MESSAGE_ID";
-    private static final String EXTRA_QUERY_STRING = "QUERY_STRING";
+    public static final String EXTRA_ACCOUNT_ID = "ACCOUNT_ID";
+    public static final String EXTRA_MAILBOX_ID = "MAILBOX_ID";
+    public static final String EXTRA_MESSAGE_ID = "MESSAGE_ID";
+    public static final String EXTRA_QUERY_STRING = "QUERY_STRING";
 
     /** Loader IDs starting with this is safe to use from UIControllers. */
     static final int UI_CONTROLLER_LOADER_ID_BASE = 100;