/**
 * 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 = {};

	/**
	 * Enable pulling out submitted value by its name
	 *
	 * @param key
	 * @returns {null|string|*}
	 * @deprecated I think this has been superseded, by page.js, but I need to investigate
	 */
	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');

		this.baselineSend('LOADING');
		this.page = new Page();
		this.page.get(page);
		this.baselineClear();
	}

	/**
	 * Load a message frame
	 *
	 * @param pagenum
	 */
	this.loadMessage = function(pagenum,ext) {
		log(LOG_ERROR,'Loading Message :['+pagenum+']');

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

		if (! msg)
			return false;

		// @todo Search 1zzzzEE..., 1zzzz...
		this.get(new PageObject(MAIL_TEMPLATE_FRAME),ext);

		if (this.page.name.toString() === null) {
			log(LOG_ERROR,'Echomail template missing :['+JSON.stringify(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 = this.page.raw.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);
					}
				}
			);
		}

		this.page.name = new PageObject(pagenum,'a');
		this.page.owner = 1;
		// @todo Keys should map to next/previous/send, etc as indicated in the template frame.
		this.page.key = [this.page.name.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.page.type = FRAME_TYPE_MESSAGE;
		// @todo Take the cost from the template
		this.page.cost = 5;
		// @todo Take the key values from the template
		this.page.__properties__.isAccessible = true;
		this.page.__properties__.isPublic = true;

		this.page.preload(msg_header+msg.content,'txt');

		// Update the user's pointers
		var stats = ma.getUserStats(this.page.name.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.page.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.page.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.page.name.frame);
		if (x)
			this.page.key[4] = area.page(x.tags);

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

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

		return true;
	}

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

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