var querystring = require("querystring");
var fs = require("fs");
var pathlib = require("path");
var formidable = require("formidable");

var basepath = "/admin/api/";

// Used in every method handler to make sure the correct arguments are provided
function hasargs(query, respond, expected) {
	var missing = [];
	for (var e of expected) {
		if (query[e] === undefined)
			missing.push(e);
	}

	if (missing.length > 0) {
		respond("Missing arguments: "+missing.join(", "));
		return false;
	} else {
		return true;
	}
}

// Method handlers are defined here
var methods = {

	// List all slides in the slides directory
	list_slides: function(query, conf, req, respond) {
		fs.readdir(conf.slides, (err, files) => {
			if (err)
				return respond(err);

			respond(null, files);
		});
	},

	// Get metadata about a slide
	slide_meta: function(query, conf, req, respond) {
		if (!hasargs(query, respond, [ "slide" ])) return;

		var path = pathlib.join(conf.slides, query.slide);
		fs.stat(path, (err, stat) => {
			if (err || !stat.isDirectory())
				return respond(path+" is not a slide.");

			fs.readFile(pathlib.join(path, "meta.json"), (err, res) => {
				if (err && err.code === "ENOENT")
					return respond(null, {});
				else if (err)
					return respond(err);

				try {
					respond(null, JSON.parse(res));
				} catch (err) {
					respond(err);
				}
			});
		});
	},

	// Get a list of files of a slide
	slide_file_list: function(query, conf, req, respond) {
		if (!hasargs(query, respond, [ "slide" ])) return;

		var dir = pathlib.join(conf.slides, query.slide);
		fs.readdir(dir, (err, files) => {
			if (err)
				return respond(err);

			respond(null, { files: files });
		});
	},

	// Get a slide's HTML
	slide_content: function(query, conf, req, respond) {
		if (!hasargs(query, respond, [ "slide" ])) return;

		var path = pathlib.join(conf.slides, query.slide, "index.md");
		fs.readFile(path, "utf-8", (err, text) => {
			if (err && err.code === "ENOENT")
				return respond(null, { text: "" });
			else if (err)
				return respond(err);

			respond(null, { text: text });
		});
	},

	// Update a slide's HTML
	slide_content_update: function(query, conf, req, respond) {
		if (!hasargs(query, respond, [ "slide", "text" ])) return;

		var path = pathlib.join(conf.slides, query.slide, "index.md");
		fs.writeFile(path, query.text, err => {
			respond(err);
		});
	},

	// Rename a file
	slide_file_rename: function(query, conf, req, respond) {
		if (!hasargs(query, respond, [ "slide", "from", "to" ])) return;

		var op = pathlib.join(conf.slides, query.slide, query.from);
		var np = pathlib.join(conf.slides, query.slide, query.to);

		fs.rename(op, np, err => respond(err));
	},

	// Delete a file
	slide_file_delete: function(query, conf, req, respond) {
		if (!hasargs(query, respond, [ "slide", "file" ])) return;

		var path = pathlib.join(conf.slides, query.slide, query.file);
		fs.unlink(path, err => respond(err));
	},

	// Upload a file to a slide
	slide_file_upload: function(query, conf, req, respond) {
		if (!hasargs(query, respond, [ "slide" ])) return;

		var form = new formidable.IncomingForm();
		form.uploadDir = pathlib.join(conf.slides, query.slide);
		form.keepExtensions = true;

		form.on("fileBegin", (name, file) => {
			file.path = pathlib.join(form.uploadDir, file.name);
		});

		form.parse(req, (err, fields, files) => {
			respond();
		});
	}
}

exports.canServe = function(parts) {
	// Temporary, while working on stuff
	return false;
	return methods[parts.pathname.replace(basepath, "")] !== undefined;
}

exports.serve = function(parts, conf, req, res) {
	var fn = methods[parts.pathname.replace(basepath, "")];
	if (!fn) {
		res.writeHead(404);
		res.end();
		return;
	}

	var query = querystring.parse(parts.query);
	for (var i in query) {
		query[i] = decodeURIComponent(query[i]);
	}

	// Better than manually doing res.end(JSON.stringify(obj)) everywhere
	function respond(err, obj) {
		var result = {
			obj: obj,
			err: err ? err.toString() : null
		};

		if (err)
			res.writeHead(400);
		else
			res.writeHead(200);

		res.end(JSON.stringify(result));
	}

	// Finally, call method handler
	fn(query, conf, req, respond);
}