import { JSWLogger } from "jsw-logger";
import * as _ from "lodash";

import { SelectorMatcher } from "./SelectorMatcher";

import { ObjectId } from "../document/index";

interface IClause {
	key: string;
	kind: string;
	type: string;
	value: any;
}

export class Selector {
	public static MATCH_SELECTOR = "match";
	public static SORT_SELECTOR = "sort";
	public static FIELD_SELECTOR = "field";
	public static AGG_FIELD_SELECTOR = "project";

	public selectorCompiled;
	public clauses;

	protected logger: JSWLogger;

	constructor(selector, type = Selector.MATCH_SELECTOR) {
		this.logger = JSWLogger.instance;

		this.selectorCompiled = null;

		if (type === Selector.MATCH_SELECTOR) {
			this.selectorCompiled = this.compile(selector);
		} else if (type === Selector.SORT_SELECTOR) {
			return this.compileSort(selector);
		} else if (type === Selector.FIELD_SELECTOR) {
			return this.compileFields(selector, false);
		} else if (type === Selector.AGG_FIELD_SELECTOR) {
			return this.compileFields(selector, true);
		} else {
			this.logger.throw("You need to specify the selector type");
		}
	}

	public test(doc) {
		return this.selectorCompiled.test(doc);
	}

	public compile(selector) {
		if (_.isNil(selector)) {
			this.logger.debug("selector -> null");

			selector = {};
		} else {
			this.logger.debug("selector -> not null");

			if (!selector || (_.hasIn(selector, "_id") && !selector._id)) {
				this.logger.debug("selector -> false value || { _id: false value }");

				selector = {
					_id: false
				};
			}
		}

		if (_.isFunction(selector)) {
			this.logger.debug("selector -> function(doc) { ... }");

			// _initFunction.call(matcher, selector);
			this.clauses = [{
				kind: "function",
				value: selector
			}];

			this.logger.debug("clauses created: " + JSON.stringify(this.clauses));
		} else if (_.isString(selector) || _.isNumber(selector)) {
			this.logger.debug("selector -> \"123456789\" || 123456798");

			selector = {
				_id: selector
			};

			// _initObject.call(matcher, selector);
			this.clauses = this.__buildSelector(selector);

			this.logger.debug("clauses created: " + JSON.stringify(this.clauses));
		} else {
			this.logger.debug("selector -> { field: value }");

			// _initObject.call(matcher, selector);
			this.clauses = this.__buildSelector(selector);

			this.logger.debug("clauses created: " + JSON.stringify(this.clauses));
		}

		const matcher = new SelectorMatcher(this);

		return matcher;
	}

	public compileSort(spec) {
		if (_.isNil(spec)) {
			return () => {
				return 0;
			};
		}

		const keys = [];
		const asc = [];

		if (_.isString(spec)) {
			spec = spec.replace(/( )+/ig, " ").trim();

			if (spec.indexOf(",") !== -1) {
				// Replace commas by spaces, and treat it as a spaced-separated string
				return this.compileSort(spec.replace(/,/ig, " "));
			} else if (spec.indexOf(" ") !== -1) {
				const fields = spec.split(" ");

				for (let i = 0; i < fields.length; i++) {
					const field = fields[i].trim();

					if ((field === "desc" || field === "asc") ||
						(field === "-1" || field === "1") ||
						(field === "false" || field === "true")) {

						this.logger.throw("Bad sort specification: %s", JSON.stringify(spec));
					} else {
						const next = _.toString(fields[i + 1]);

						if (next === "desc" || next === "asc") {
							keys.push(field);
							asc.push((next === "asc") ? true : false);

							i++;
						} else if (next === "-1" || next === "1") {
							keys.push(field);
							asc.push((next === "1") ? true : false);

							i++;
						} else if (next === "false" || next === "true") {
							keys.push(field);
							asc.push((next === "true") ? true : false);

							i++;
						} else {
							keys.push(field);
							asc.push(true); // Default sort
						}
					}
				}
			} else {
				// .sort("field1")

				keys.push(spec);
				asc.push(true);
			}
		} else if (_.isArray(spec)) {
			// Join the array with spaces, and treat it as a spaced-separated string
			return this.compileSort(spec.join(" "));
			// for (var i = 0; i < spec.length; i++) {
			// 	 if (_.isString(spec[i])) {
			// 		 keys.push(spec[i]);
			// 		 asc.push(true);
			// 	 } else {
			// 		 keys.push(spec[i][0]);
			// 		 asc.push(spec[i][1] !== "desc");
			// 	 }
			// }
		} else if (_.isPlainObject(spec)) {
			// TODO Nested path -> .sort({ "field1.field12": "asc" })
			const _spec = [];
			for (const key in spec) {
				if (_.hasIn(spec, key)) {
					_spec.push(key);
					_spec.push(spec[key]);
				}
			}

			return this.compileSort(_spec);
		} else {
			this.logger.throw("Bad sort specification: %s", JSON.stringify(spec));
		}

		// return {keys: keys, asc: asc};
		return (a, b) => {
			let x = 0;

			for (let i = 0; i < keys.length; i++) {
				if (i !== 0 && x !== 0) { return x; }   // Non reachable?

				// x = Selector._f._cmp(a[JSON.stringify(keys[i])], b[JSON.stringify(keys[i])]);
				x = SelectorMatcher.cmp(a[keys[i]], b[keys[i]]);

				if (!asc[i]) {
					x *= -1;
				}
			}

			return x;
		};

		// eval() does not return a value in IE8, nor does the spec say it
		// should. Assign to a local to get the value, instead.

		// var _func;
		// var code = "_func = (function(c){return function(a,b){var x;";
		// for (var i = 0; i < keys.length; i++) {
		// 	 if (i !== 0) {
		// 		 code += "if(x!==0)return x;";
		// 	 }

		// 	 code += "x=" + (asc[i] ? "" : "-") + "c(a[" + JSON.stringify(keys[i]) + "],b[" + JSON.stringify(keys[i]) + "]);";
		// }

		// code += "return x;};})";

		// eval(code);

		// return _func(Selector._f._cmp);
	}

	public compileFields(spec, aggregation) {
		const projection = {};

		if (_.isNil(spec)) { return projection; }

		if (_.isString(spec)) {
			// trim surrounding and inner spaces
			spec = spec.replace(/( )+/ig, " ").trim();

			// Replace the commas by spaces
			if (spec.indexOf(",") !== -1) {
				// Replace commas by spaces, and treat it as a spaced-separated string
				return this.compileFields(spec.replace(/,/ig, " "), aggregation);
			} else if (spec.indexOf(" ") !== -1) {
				const fields = spec.split(" ");

				for (let i = 0; i < fields.length; i++) {
					// Get the field from the spec (we will be working with pairs)
					const field = fields[i].trim();

					// If the first is not a field, throw error
					if ((field === "-1" || field === "1") ||
						(field === "false" || field === "true")) {

						this.logger.throw("Bad fields specification: %s", JSON.stringify(spec));
					} else {
						// Get the next item of the pair
						const next = _.toString(fields[i + 1]);

						if (next === "-1" || next === "1") {
							if (next === "-1") {
								for (const _key in projection) {
									if (field !== "_id" && projection[_key] === 1) {
										this.logger.throw("A projection cannot contain both include and exclude specifications");
									}
								}

								projection[field] = -1;
							} else {
								projection[field] = 1;
							}

							i++;
						} else if (next === "false" || next === "true") {
							if (next === "false") {
								if (field === "_id") {
									projection[field] = -1;
								} else {
									this.logger.throw("A projection cannot contain both include and exclude specifications");
								}
							} else {
								projection[field] = 1;
							}

							i++;
						} else if (aggregation && next.indexOf("$") === 0) {
							projection[field] = next.replace("$", "");

							i++;
						} else {
							projection[field] = 1;
						}
					}
				}
			} else if (spec.length > 0) {
				// .find({}, "field1")

				projection[spec] = 1;
			}
		} else if (_.isArray(spec)) {
			// Join the array with spaces, and treat it as a spaced-separated string
			return this.compileFields(spec.join(" "), aggregation);
		} else if (_.isPlainObject(spec)) {
			// TODO Nested path -> .find({}, { "field1.field12": "asc" })
			const _spec = [];
			for (const key in spec) {
				if (_.hasIn(spec, key)) {
					_spec.push(key);
					_spec.push(spec[key]);
				}
			}

			return this.compileFields(_spec, aggregation);
		} else {
			this.logger.throw("Bad fields specification: %s", JSON.stringify(spec));
		}

		return projection;
	}

	private createClause(): IClause {
		return {
			key: null,
			kind: null,
			type: null,
			value: null
		} as IClause;
	}

	private __buildSelector(selector) {
		this.logger.debug("Called: __buildSelector");

		const clauses = [];

		for (const key of Object.keys(selector)) {
			const value = selector[key];

			if (key.charAt(0) === "$") {
				this.logger.debug("selector -> operator => { $and: [{...}, {...}] }");

				clauses.push(this.buildDocumentSelector(key, value));
			} else {
				this.logger.debug("selector -> plain => { field1: <value> }");

				clauses.push(this.buildKeypathSelector(key, value));
			}
		}

		return clauses;
	}

	private buildDocumentSelector(key, value) {
		const clause: IClause = this.createClause();

		switch (key) {
			case "$or":
			// falls through
			case "$and":
			// falls through
			case "$nor":
				clause.key = key.replace(/\$/, "");

			// falls through
			// The rest will be handled by "_operator_"
			case "_operator_":
				// Generic handler for operators ($or, $and, $nor)

				clause.kind = "operator";
				clause.type = "array";

				clause.value = [];
				for (const item of value) {
					clause.value = _.union(clause.value, this.__buildSelector(item));
				}

				break;
			default:
				this.logger.throw("Unrecogized key in selector: %s", key);
		}

		// TODO cases: $where, $elemMatch

		this.logger.debug("clause created: " + JSON.stringify(clause));

		return clause;
	}

	private buildKeypathSelector(keypath, value) {
		this.logger.debug("Called: buildKeypathSelector");

		const clause: IClause = this.createClause();

		clause.value = value;

		if (_.isNil(value)) {
			this.logger.debug("clause of type null");

			clause.type = "null";
		} else if (_.isRegExp(value)) {
			this.logger.debug("clause of type RegExp");

			clause.type = "regexp";

			const source = value.toString().split("/");

			clause.value = {
				$regex: source[1]   // The first item splitted is an empty string
			};

			if (source[2] !== "") {
				clause.value.$options = source[2];
			}
		} else if (_.isArray(value)) {
			this.logger.debug("clause of type Array");

			clause.type = "array";
		} else if (_.isString(value)) {
			this.logger.debug("clause of type String");

			clause.type = "string";
		} else if (_.isNumber(value)) {
			this.logger.debug("clause of type Number");

			clause.type = "number";
		} else if (_.isBoolean(value)) {
			this.logger.debug("clause of type Boolean");

			clause.type = "boolean";
		} else if (_.isFunction(value)) {
			this.logger.debug("clause of type Function");

			clause.type = "function";
		} else if (_.isPlainObject(value)) {
			let literalObject = true;
			for (const key in value) {
				if (key.charAt(0) === "$") {
					literalObject = false;

					break;
				}
			}

			if (literalObject) {
				this.logger.debug("clause of type Object => { field: { field_1: <value>, field_2: <value> } }");

				clause.type = "literal_object";
			} else {
				this.logger.debug("clause of type Operator => { field: { $gt: 2, $lt 5 } }");

				clause.type = "operator_object";
			}
		} else if (value instanceof ObjectId) {
			this.logger.debug("clause of type ObjectId -> String");

			clause.type = "string";
			clause.value = value.toString();
		} else {
			clause.type = "__invalid__";
		}

		const parts = keypath.split(".");
		if (parts.length > 1) {
			this.logger.debug("clause over Object field => { \"field1.field1_2\": <value> }");

			clause.kind = "object";
			clause.key = parts;
		} else {
			this.logger.debug("clause over Plain field => { \"field\": <value> }");

			clause.kind = "plain";
			clause.key = parts[0];
		}

		this.logger.debug("clause created: " + JSON.stringify(clause));

		return clause;
	}

	/* STATIC METHODS */
	public static isSelectorCompiled(selector) {
		if (!_.isNil(selector) && (
			selector instanceof SelectorMatcher || (selector instanceof Selector &&
				selector.selectorCompiled instanceof SelectorMatcher)
		)) {
			return true;
		} else {
			return false;
		}
	}

	public static matches(selector, doc) {
		return (new Selector(selector)).test(doc);
	}
}