/*!
 * Express - View
 * Copyright(c) 2010 TJ Holowaychuk <tj@vision-media.ca>
 * MIT Licensed
 */

/**
 * Module dependencies.
 */

var path = require( 'path' )
	, utils = require( '../utils' )
	, extname = path.extname
	, dirname = path.dirname
	, basename = path.basename
	, fs = require( 'fs' )
	, stat = fs.statSync;

/**
 * Expose `View`.
 */

exports = module.exports = View;

/**
 * Require cache.
 */

var cache = {};

/**
 * Initialize a new `View` with the given `view` path and `options`.
 *
 * @param {String} view
 * @param {Object} options
 * @api private
 */

function View( view, options ) {
	options = options || {};
	this.view = view;
	this.root = options.root;
	this.relative = false !== options.relative;
	this.defaultEngine = options.defaultEngine;
	this.parent = options.parentView;
	this.basename = basename( view );
	this.engine = this.resolveEngine();
	this.extension = '.' + this.engine;
	this.name = this.basename.replace( this.extension, '' );
	this.path = this.resolvePath();
	this.dirname = dirname( this.path );
	if ( options.attempts ) {
		if ( !~options.attempts.indexOf( this.path ) ) {
			options.attempts.push( this.path );
		}
	}
}
;

/**
 * Check if the view path exists.
 *
 * @return {Boolean}
 * @api public
 */

View.prototype.__defineGetter__( 'exists', function () {
	try {
		stat( this.path );
		return true;
	} catch ( err ) {
		return false;
	}
} );

/**
 * Resolve view engine.
 *
 * @return {String}
 * @api private
 */

View.prototype.resolveEngine = function () {
	// Explicit
	if ( ~this.basename.indexOf( '.' ) ) {
		return extname( this.basename ).substr( 1 );
	}
	// Inherit from parent
	if ( this.parent ) {
		return this.parent.engine;
	}
	// Default
	return this.defaultEngine;
};

/**
 * Resolve view path.
 *
 * @return {String}
 * @api private
 */

View.prototype.resolvePath = function () {
	var path = this.view;
	// Implicit engine
	if ( !~this.basename.indexOf( '.' ) ) {
		path += this.extension;
	}
	// Absolute
	if ( utils.isAbsolute( path ) ) {
		return path;
	}
	// Relative to parent
	if ( this.relative && this.parent ) {
		return this.parent.dirname + '/' + path;
	}
	// Relative to root
	return this.root
		? this.root + '/' + path
		: path;
};

/**
 * Get view contents. This is a one-time hit, so we
 * can afford to be sync.
 *
 * @return {String}
 * @api public
 */

View.prototype.__defineGetter__( 'contents', function () {
	return fs.readFileSync( this.path, 'utf8' );
} );

/**
 * Get template engine api, cache exports to reduce
 * require() calls.
 *
 * @return {Object}
 * @api public
 */

View.prototype.__defineGetter__( 'templateEngine', function () {
	var ext = this.extension;
	return cache[ext] || (cache[ext] = require( this.engine ));
} );

/**
 * Return root path alternative.
 *
 * @return {String}
 * @api public
 */

View.prototype.__defineGetter__( 'rootPath', function () {
	this.relative = false;
	return this.resolvePath();
} );

/**
 * Return index path alternative.
 *
 * @return {String}
 * @api public
 */

View.prototype.__defineGetter__( 'indexPath', function () {
	return this.dirname
		       + '/' + this.basename.replace( this.extension, '' )
		       + '/index' + this.extension;
} );

/**
 * Return ../<name>/index path alternative.
 *
 * @return {String}
 * @api public
 */

View.prototype.__defineGetter__( 'upIndexPath', function () {
	return this.dirname + '/../' + this.name + '/index' + this.extension;
} );

/**
 * Return _ prefix path alternative
 *
 * @return {String}
 * @api public
 */

View.prototype.__defineGetter__( 'prefixPath', function () {
	return this.dirname + '/_' + this.basename;
} );

/**
 * Register the given template engine `exports`
 * as `ext`. For example we may wish to map ".html"
 * files to jade:
 *
 *    app.register('.html', require('jade'));
 *
 * or
 *
 *    app.register('html', require('jade'));
 *
 * This is also useful for libraries that may not
 * match extensions correctly. For example my haml.js
 * library is installed from npm as "hamljs" so instead
 * of layout.hamljs, we can register the engine as ".haml":
 *
 *    app.register('.haml', require('haml-js'));
 *
 * @param {String} ext
 * @param {Object} obj
 * @api public
 */

exports.register = function ( ext, exports ) {
	if ( '.' != ext[0] ) {
		ext = '.' + ext;
	}
	cache[ext] = exports;
};