// Initialise. If the database doesn't exist, it is created
var lib = new localStorageDB("library", localStorage);

// Check if the database was just created. Useful for initial database setup
if( lib.isNew() ) {

    // create the "books" table
	lib.createTable("books", ["code", "title", "author", "year", "copies"]);

	// insert some data
	lib.insert("books", {code: "B001", title: "Phantoms in the brain", author: "Ramachandran", year: 1999, copies: 10});
	lib.insert("books", {code: "B002", title: "The tell-tale brain", author: "Ramachandran", year: 2011, copies: 10});
	lib.insert("books", {code: "B003", title: "Freakonomics", author: "Levitt and Dubner", year: 2005, copies: 10});
	lib.insert("books", {code: "B004", title: "Predictably irrational", author: "Ariely", year: 2008, copies: 10});
	lib.insert("books", {code: "B005", title: "Tesla: Man out of time", author: "Cheney", year: 2001, copies: 10});
	lib.insert("books", {code: "B006", title: "Salmon fishing in the Yemen", author: "Torday", year: 2007, copies: 10});
	lib.insert("books", {code: "B007", title: "The user illusion", author: "Norretranders", year: 1999, copies: 10});
	lib.insert("books", {code: "B008", title: "Hubble: Window of the universe", author: "Sparrow", year: 2010, copies: 10});

	// commit the database to localStorage
	// all create/drop/insert/update/delete operations should be committed
	lib.commit();
}

// If database already exists, and want to alter existing tables
if(! (lib.columnExists("books", "publication")) ) {
	lib.alterTable("books", "publication", "McGraw-Hill Education");
	lib.commit(); // commit the deletions to localStorage
}

// Multiple columns can also added at once
if(! (lib.columnExists("books", "publication") && lib.columnExists("books", "ISBN")) ) {
	lib.alterTable("books", ["publication", "ISBN"], {publication: "McGraw-Hill Education", ISBN: "85-359-0277-5"});
	lib.commit(); // commit the deletions to localStorage
}

// simple select queries
lib.queryAll("books", {
	query: {year: 2011}
});
lib.queryAll("books", {
	query: {year: 1999, author: "Norretranders"}
});

// select all books
lib.queryAll("books");

// select all books published after 2003
lib.queryAll("books", {
	query: function(row) {    // the callback function is applied to every row in the table
		if(row.year > 2003) {		// if it returns true, the row is selected
			return true;
		} else {
			return false;
		}
	}
});

// select all books by Torday and Sparrow
lib.queryAll("books", {
    query: function(row) {
            if(row.author == "Torday" || row.author == "Sparrow") {
		        return true;
	        } else {
		        return false;
	    }
    },
    limit: 5
});

// select 5 rows sorted in ascending order by author
lib.queryAll("books", { limit: 5,
                        sort: [["author", "ASC"]]
                      });

// select all rows first sorted in ascending order by author, and then, in descending, by year
lib.queryAll("books", { sort: [["author", "ASC"], ["year", "DESC"]] });

lib.queryAll("books", { query: {"year": 2011},
                        limit: 5,
                        sort: [["author", "ASC"]]
                      });

// or using query()'s positional arguments, which is a little messy (DEPRECATED)
lib.query("books", null, null, null, [["author", "ASC"]]);

lib.queryAll("books", { distinct: ["year", "author"]
                      });

// query results are returned as arrays of object literals
// an ID field with the internal auto-incremented id of the row is also included
// thus, ID is a reserved field name

lib.queryAll("books", {query: {author: "ramachandran"}});

/* results
[
 {
   ID: 1,
   code: "B001",
   title: "Phantoms in the brain",
   author: "Ramachandran",
   year: 1999,
   copies: 10
 },
 {
   ID: 2,
   code: "B002",
   title: "The tell-tale brain",
   author: "Ramachandran",
   year: 2011,
   copies: 10
 }
]
*/

// change the title of books published in 1999 to "Unknown"
lib.update("books", {year: 1999}, function(row) {
	row.title = "Unknown";

	// the update callback function returns to the modified record
	return row;
});

// add +5 copies to all books published after 2003
lib.update("books",
	function(row) {	// select condition callback
		if(row.year > 2003) {
			return true;
		} else {
			return false;
		}
	},
	function(row) { // update function
		row.copies+=5;
		return row;
	}
);

// if there's a book with code B003, update it, or insert it as a new row
lib.insertOrUpdate("books", {code: 'B003'}, {	code: "B003",
						title: "Freakonomics",
						author: "Levitt and Dubner",
						year: 2005,
						copies: 15});

lib.commit();

// delete all books published in 1999
lib.deleteRows("books", {year: 1999});

// delete all books published before 2005
lib.deleteRows("books", function(row) {
	if(row.year < 2005) {
		return true;
	} else {
		return false;
	}
});

lib.commit(); // commit the deletions to localStorage