/**
 * URL Template v2.0.6 (https://github.com/bramstein/url-template)
 */

export function expand(url, params, variables) {

    var tmpl = parse(url), expanded = tmpl.expand(params);

    if (variables) {
        variables.push.apply(variables, tmpl.vars);
    }

    return expanded;
}

export function parse(template) {

    var operators = ['+', '#', '.', '/', ';', '?', '&'], variables = [];

    return {
        vars: variables,
        expand(context) {
            return template.replace(/\{([^{}]+)\}|([^{}]+)/g, (_, expression, literal) => {
                if (expression) {

                    var operator = null, values = [];

                    if (operators.indexOf(expression.charAt(0)) !== -1) {
                        operator = expression.charAt(0);
                        expression = expression.substr(1);
                    }

                    expression.split(/,/g).forEach((variable) => {
                        var tmp = /([^:*]*)(?::(\d+)|(\*))?/.exec(variable);
                        values.push.apply(values, getValues(context, operator, tmp[1], tmp[2] || tmp[3]));
                        variables.push(tmp[1]);
                    });

                    if (operator && operator !== '+') {

                        var separator = ',';

                        if (operator === '?') {
                            separator = '&';
                        } else if (operator !== '#') {
                            separator = operator;
                        }

                        return (values.length !== 0 ? operator : '') + values.join(separator);
                    } else {
                        return values.join(',');
                    }

                } else {
                    return encodeReserved(literal);
                }
            });
        }
    };
}

function getValues(context, operator, key, modifier) {

    var value = context[key], result = [];

    if (isDefined(value) && value !== '') {
        if (typeof value === 'string' || typeof value === 'number' || typeof value === 'boolean') {
            value = value.toString();

            if (modifier && modifier !== '*') {
                value = value.substring(0, parseInt(modifier, 10));
            }

            result.push(encodeValue(operator, value, isKeyOperator(operator) ? key : null));
        } else {
            if (modifier === '*') {
                if (Array.isArray(value)) {
                    value.filter(isDefined).forEach((value) => {
                        result.push(encodeValue(operator, value, isKeyOperator(operator) ? key : null));
                    });
                } else {
                    Object.keys(value).forEach((k) => {
                        if (isDefined(value[k])) {
                            result.push(encodeValue(operator, value[k], k));
                        }
                    });
                }
            } else {
                var tmp = [];

                if (Array.isArray(value)) {
                    value.filter(isDefined).forEach((value) => {
                        tmp.push(encodeValue(operator, value));
                    });
                } else {
                    Object.keys(value).forEach((k) => {
                        if (isDefined(value[k])) {
                            tmp.push(encodeURIComponent(k));
                            tmp.push(encodeValue(operator, value[k].toString()));
                        }
                    });
                }

                if (isKeyOperator(operator)) {
                    result.push(encodeURIComponent(key) + '=' + tmp.join(','));
                } else if (tmp.length !== 0) {
                    result.push(tmp.join(','));
                }
            }
        }
    } else {
        if (operator === ';') {
            result.push(encodeURIComponent(key));
        } else if (value === '' && (operator === '&' || operator === '?')) {
            result.push(encodeURIComponent(key) + '=');
        } else if (value === '') {
            result.push('');
        }
    }

    return result;
}

function isDefined(value) {
    return value !== undefined && value !== null;
}

function isKeyOperator(operator) {
    return operator === ';' || operator === '&' || operator === '?';
}

function encodeValue(operator, value, key) {

    value = (operator === '+' || operator === '#') ? encodeReserved(value) : encodeURIComponent(value);

    if (key) {
        return encodeURIComponent(key) + '=' + value;
    } else {
        return value;
    }
}

function encodeReserved(str) {
    return str.split(/(%[0-9A-Fa-f]{2})/g).map((part) => {
        if (!/%[0-9A-Fa-f]/.test(part)) {
            part = encodeURI(part);
        }
        return part;
    }).join('');
}