PetProvider

package com.example.android.pets.data;

import com.example.android.pets.data.PetContract.PetEntry;
import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.support.annotation.Nullable;
import android.util.Log;

import static android.R.attr.id;
import static com.example.android.pets.data.PetContract.CONTENT_AUTHORITY;
import static com.example.android.pets.data.PetContract.PATH_PETS;
import static com.example.android.pets.data.PetContract.PetEntry.COLUMN_PET_BREED;
import static com.example.android.pets.data.PetContract.PetEntry.COLUMN_PET_GENDER;
import static com.example.android.pets.data.PetContract.PetEntry.COLUMN_PET_NAME;
import static com.example.android.pets.data.PetContract.PetEntry.COLUMN_PET_WEIGHT;
import static com.example.android.pets.data.PetContract.PetEntry.CONTENT_URI;
import static com.example.android.pets.data.PetContract.PetEntry.GENDER_MALE;
import static com.example.android.pets.data.PetContract.PetEntry.GENDER_UNKNOWN;
import static com.example.android.pets.data.PetContract.PetEntry.TABLE_NAME;
import static com.example.android.pets.data.PetContract.PetEntry._ID;


/**
 * Created by AGUELE OSEKUEMEN JOE on 5/29/2017.
 * ContentProvider for Pets app.
 */

public class PetProvider extends ContentProvider {

    private static final String LOG_TAG = PetProvider.class.getSimpleName();
    /**Database helper object*/
    private PetDbHelper mDbHelper;

    // URI matcher code for the content URI for teh pets table
    private static final int PETS = 100;

    // URI matcher code for the content URI for a single pet in the pets table
    private static final int PETS_ID = 101;

    /**
     * UriMatcher object to match a content URI to a corresponding code.
     * The input passed into the constructor represents the code to return for the root URI
     * It's common to use NO_MATCH as the input for this case
     */
    private static final UriMatcher sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);

    // Static initializer. This is run the first time anything is called from this class.
    static{
        // The calls to addURI() go here, for all of the content URI patterns that the provider
        // should recognize. All paths added to the UriMatcher have a corresponding code to return
        // when a match is found.
        sUriMatcher.addURI(CONTENT_AUTHORITY, PATH_PETS, PETS);
        sUriMatcher.addURI(CONTENT_AUTHORITY, PATH_PETS +"/#", PETS_ID);
    }

    // Initialize the provider and the database helper object.
    @Override
    public boolean onCreate() {
        mDbHelper = new PetDbHelper(getContext());
        return true;
    }

    // Perform the query for the given URI. Use the given projection, selection, selection arguments, and sort order.
    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
        //  Get readable database
        SQLiteDatabase database = mDbHelper.getReadableDatabase();

        // This cursor will hold the result of the query
        Cursor cursor;

        // Figure out if the URI matcher can match the URI to a specific code
        int match = sUriMatcher.match(uri);
        switch(match){
            case PETS:
                // For the PETS code, query the pets table directly wit the given
                // projection, selection, selection arguments and sort order. The cursor
                // could contain multiple rows of the pets table.
                // TODO: Perform database query on pets table.
                cursor = database.query(TABLE_NAME, projection, selection, selectionArgs,null, null, sortOrder);
                break;
            case PETS_ID:
                //For the PET_ID code, extract out the ID from the URI.
                // For an example URI such as "com.example.android.pets/pets/3",
                // the selection will be "_id=?" and the selection argument will be a
                // String array containing the actual ID of 3 in this case.

                // For every "?" in the selection, we need to have an element in the selection
                // arguments that will fill in the "?". Since we have 1 question mark in the
                // selection, we have 1 String in the selection arguments String array.
                selection = PetEntry._ID + "=?";
                selectionArgs = new String[]{String.valueOf(ContentUris.parseId(uri))};

                // This will perform a query on the pets able where the _id equals 3 to return a
                // Cursor containing that row of the table.
                cursor = database.query(TABLE_NAME, projection, selection, selectionArgs,
                        null, null, sortOrder);
                break;
            default:
                throw new IllegalArgumentException("Cannot query unknown URI" + uri);
        }
        return cursor;
    }

    // Returns the MIME type of data for the content URI.
    @Override
    public String getType(Uri uri) {
        return null;
    }

    // Insert new data into the provider with the given ContentValues.
    @Override
    public Uri insert(Uri uri, ContentValues contentValues) {
        final int match = sUriMatcher.match(uri); // URI matcher is used to check if there is a match
        switch(match){
            case PETS:
                return insertPet(uri, contentValues);
            default:
                throw new IllegalArgumentException("Insertion is not supported for " +uri);
        }
    }

    //Insert a pet into the database with thegiven content values. Return the ne content URI
    // for that specific row in the database
    private Uri insertPet(Uri uri, ContentValues values){
        //check that the name is not null
        String name = values.getAsString(COLUMN_PET_NAME);
        if (name == null){
            throw new IllegalArgumentException("Pet requires a name");
        }

        // Check that the gender is not null
        Integer gender = values.getAsInteger(COLUMN_PET_GENDER);
        if (gender == null || !PetEntry.isValidGender(gender)){
            throw new IllegalArgumentException("Pet requires a valid gender");
        }

        // If the weight is provided, check that it is greater than or equal to 0kg
        /*
        * If the weight is null, that's fine and we can proceed with insertion (the database will insert
        * default weight 0 automatically) if the wieght is not null AND it's a negative wieght, then we
        * to throw an exception with the message "Pet requires valid weight". We use the "&&" SYMBOL
        * to indicate that both "weight != null" must be true and "weight < 0" must be true, in order
        * for the whole test condition to be true, and for the code within the "if" statement to
        * execute
        * */
        Integer weight = values.getAsInteger(COLUMN_PET_WEIGHT);
        if( weight != null && weight < 0 ) {
            throw new IllegalArgumentException("Pet weight can't be less than zero");
        }


        //Get writeable database
        SQLiteDatabase database = mDbHelper.getWritableDatabase();

        // insert the new pet with the given values
        long id = database.insert(TABLE_NAME,null,values);
        //If the ID is -1, then the insertion failed. Log an error and return null.
        if (id == -1){
            Log.e(LOG_TAG, "Failed to insert row for " + uri);
            return null;
        }
        // return the new URI with the ID (of the newly inserted row) appended to the end of it
        return ContentUris.withAppendedId(uri, id);

    }

    // Delete data at the given selection and selection arguments
    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        return 0;
    }

    @Override
    public int update(Uri uri, ContentValues contentValues, String selection, String[] selectionArgs) {
       final int match = sUriMatcher.match(uri);
        switch(match){
            case PETS:
                return updatePet(uri, contentValues, selection, selectionArgs);
            case PETS_ID:
                // For the PETS_ code, extract out the ID from the URI,
                // so we know which row to update. Selection will be "_id=?" and selection
                // arguments will be a String array containing the actual I.
                selection = _ID + "=?";
                selectionArgs = new String[] { String.valueOf(ContentUris.parseId(uri))};
                return updatePet(uri, contentValues, selection, selectionArgs);
            default:
                throw new IllegalArgumentException("Update is not supported for " + uri);
        }
    }

    private int updatePet(Uri uri, ContentValues values, String selection, String[]selectionArgs){

        // TODO: Update the selected pets in the pets database table with the given ContentValues
        // TODO: Return the number of rows that were affected

        if (values.containsKey(COLUMN_PET_WEIGHT)){
            // Check that the weight is greater than or equal to 0kg and also
            // check that the weight is not null
            Integer weight = values.getAsInteger(COLUMN_PET_WEIGHT);
            if (weight == null || weight < 0){
                throw new IllegalArgumentException("Pets correct weight must be inputted");
            }
        }
        //Get writable database
        SQLiteDatabase database = mDbHelper.getWritableDatabase();
        selection = PetEntry._ID + "=?";
        selectionArgs = new String[]{String.valueOf(ContentUris.parseId(uri))};

        // insert the new pet with the given values
        int row = database.update(TABLE_NAME,values,selection,selectionArgs);

        return row;
    }


}