/**
 * This handles session specific aspects of each frame type, eg: sending to the baseline, clearing, accepting
 * input, moving around the frame (and windows within one if any)
 *
 * @constructor
 */
function Session() {
	'use strict';

	// Our page object
	this.page = undefined;

	/* Frame type settings */
	this.settings = {};

	/* Frame Version */
	this.version = 1;

	/* Frame Number [0-9] */
	this.frame = null;

	/* Frame Index [a-z] */
	this.index = null;

	/* The Service Provider owning the frame. */
	this.owner = 0;

	/* The cost to view the frame @todo to implement */
	this.cost = 0;

	/* The frame content, base64 encoded */
	this.content = '';

	// Frame's owned by the system where:
	// isPublic is FALSE	- the user must be logged in to view it
	// isPublic is TRUE		- can be viewed by non-logged in users

	// Frame's owned by Service Providers where:
	// isPublic is FALSE	- can only be viewed if a user is
	//          			a member of the Service Providers CUG
	// isPublic is TRUE		- can be viewed by users (if logged in)

	this.isPublic = false;				// Is this frame accessible to non CUG users
	// If FALSE user must be a member of the CUG to view the frame
	// All users, including unauthenticated, are members of 'system' (owner = 0)
	this.isAccessible = false;			// Is this frame available to be accessed
	// If FALSE, only the SP can view/edit the frame

	this.type = FRAME_TYPE_INFO;		// The frame type - see FRAME_TYPES above
	this.key = [null,null,null,null,null,null,null,null,null,null];	// Key actions [0-9]

	/**
	 * Return the frames fields
	 */
	Object.defineProperty(this,'fields', {
		get: function() {
			return this.frame_fields;
		}
	});

	/**
	 * Check if the user is already a member of the CUG
	 */
	Object.defineProperty(this,'isMember',{
		get: function() {
			log(LOG_DEBUG,'- Checking if user is a member of frame: '+this.page);

			if (user.number) {
				return (
					(this.pageowner === SYSTEM_OWNER)
				);

			} else {
				return false;
			}
		}
	})

	Object.defineProperty(this,'pageownerlogo', {
		get: function() {
			return base64_decode(this.settings.ext === 'tex' ? pageOwner(this.frame).logoans : pageOwner(this.frame).logovtx);
		}
	})

	/**
	 * Enable pulling out submitted value by its name
	 *
	 * @param key
	 * @returns {null|string|*}
	 */
	this.fieldValue = function(key) {
		for each (var k in this.frame_fields) {
			log(LOG_DEBUG,'  - k:'+JSON.stringify(k));

			if (k.fname === key) {
				return k.fvalue;
			}
		}

		return null;
	}

	this.get = function(page) {
		if (!(page instanceof PageObject))
			throw new Error('page must be a PageObject');

		switch (this.settings.ext) {
			case 'tex':
			case 'vtx':
				this.page = new Page(this.settings.ext);
				break;

			default:
				throw new Error(this.settings.ext+' has not been implemented');
		}

		this.baselineSend('LOADING');
		this.page.get(page,this.settings.ext);
		this.baselineClear();
	}

	/**
	 * Load a message frame
	 *
	 * @param page
	 */
	this.loadMessage = function(page) {
		this.frame = ''+page;
		this.index = 'a';
		this.owner = 1;
		this.isPublic = true;
		this.isAccessible = true;
		// @todo Keys should map to next/previous/send, etc as indicated in the template frame.
		this.key = [this.frame.substr(0,7)+'1',null,null,null,null,null,null,null,null,null];
		// @todo validate that FRAME_TYPE_MESSAGE is a message template
		this.type = FRAME_TYPE_MESSAGE;

		// Load our message
		var ma = new MsgAreas()
		var area = ma.getArea(this.frame);
		var msg = ma.getMessage(this.frame);
		var msg_header;

		if (! msg)
			return undefined;

		// @todo Search 1zzzzEE..., 1zzzz...
		var to = viewdata ? new FrameViewdata() : new FrameAnsi();
		to.load(MAIL_TEMPLATE_FRAME);
		// @todo Check that this is a frame of type "m" and report error if not
		// @todo Take the cost from the template
		this.cost = 5;

		if (! to) {
			log(LOG_ERROR,'Echomail template missing :['+MAIL_TEMPLATE_FRAME+'] ?');
			msg_header = 'TO: '+msg.to.substr(0,72)+"\n\r";
			msg_header += 'FROM: '+msg.from.substr(0,72)+"\n\r";
			msg_header += 'DATE: '+msg.date.substr(0,72)+"\n\r";
			msg_header += 'SUBJECT: '+msg.subject.substr(0,72)+"\n\r";

		} else {
			// @todo change this to use atcode()
			msg_header = base64_decode(to.content).replace(/@(.*)@/g,
				function (str, code, offset, s) {
					var length = code.split(':')[1];
					switch(code.split(':')[0]) {
						case 'DATE': return msg.date.substr(0,length);
						case 'TO': return msg.to.substr(0,length);
						case 'FROM': return msg.from.substr(0,length);
						case 'SUBJECT': return msg.subject.substr(0,length);
					}
				}
			);
		}

		//log(LOG_DEBUG,'Loaded message: '+msg_header+msg.content);
		this.content = base64_encode(msg_header+msg.content);

		// Update the user's pointers
		var stats = ma.getUserStats(this.frame);

		// if this message is to the user, and the msg number > scan_ptr and it is the next message on the user's new mail list
		var newmsgs = area.newMsgsToMe();
		var next;
		log(LOG_DEBUG,'User has: '+newmsgs.length-1+' msgs to read to ME');
		if (newmsgs.length) {
			next = newmsgs[1];
			//log(LOG_DEBUG,'- NEXT is: '+next.tags+', this is: '+msg.tags);

			if (next && (next.tags === msg.tags)) {
				log(LOG_DEBUG,'- Updating scan_ptr to: '+next.number);
				stats.scan_ptr = next.number;
			}

			// Last message
			next = newmsgs[0];
			if (next !== undefined) {
				log(LOG_DEBUG,'- LAST TO ME is: '+next.tags);
				this.key[1] = area.page(next.tags);
			}

			// Next new message
			next = newmsgs[2];
			if (next !== undefined) {
				log(LOG_DEBUG,'- NEXT TO ME is: '+next.tags);
				this.key[2] = area.page(next.tags);
			}
		}

		// if this message is the next message, update last_read
		newmsgs = area.newMsgs();
		log(LOG_DEBUG,'User has: '+newmsgs.length+' msgs to read');
		if (newmsgs.length) {
			next = newmsgs[0];
			log(LOG_DEBUG,'- NEXT is: '+next.tags+', this is: '+msg.tags);

			if (next.tags === msg.tags) {
				log(LOG_DEBUG,'- Updating last_read to: '+next.number);
				stats.last_read = next.number;
			}
		}

		// Previous Message
		x = area.MessagePrev(this.frame);
		if (x)
			this.key[4] = area.page(x.tags);

		// Next Message
		x = area.MessageNext(this.frame);
		if (x)
			this.key[6] = area.page(x.tags);

		log(LOG_DEBUG,'Built frame: ['+this.frame+']['+this.index+'] ('+this.page+')');
	}

	// Render the page
	this.render = function() {
		this.gotoxy(0,0);
		write(so.page.display().join(''));
	}
}

/**
 * Return the message for a index
 *
 * @param index
 * @returns {string|*}
 */
Session.prototype.getMessage = function(index) {
	eval('var msg = this.settings.'+index);
	return msg;
}