'use strict';

var KEBAB_REGEX = /[A-Z]/g;

var hash = function (str) {
    var h = 5381, i = str.length;

    while (i) h = (h * 33) ^ str.charCodeAt(--i);

    return '_' + (h >>> 0).toString(36);
};

exports.create = function (config) {
    config = config || {};
    var assign = config.assign || Object.assign;
    var client = typeof window === 'object';

    // Check if we are really in browser environment.
    if (process.env.NODE_ENV !== 'production') {
        if (client) {
            if ((typeof document !== 'object') || !document.getElementsByTagName('HTML')) {
                console.error(
                    'nano-css detected browser environment because of "window" global, but ' +
                    '"document" global seems to be defective.'
                );
            }
        }
    }

    var renderer = assign({
        raw: '',
        pfx: '_',
        client: client,
        assign: assign,
        stringify: JSON.stringify,
        kebab: function (prop) {
            return prop.replace(KEBAB_REGEX, '-$&').toLowerCase();
        },
        decl: function (key, value) {
            key = renderer.kebab(key);
            return key + ':' + value + ';';
        },
        hash: function (obj) {
            return hash(renderer.stringify(obj));
        },
        selector: function (parent, selector) {
            return parent + (selector[0] === ':' ? ''  : ' ') + selector;
        },
        putRaw: function (rawCssRule) {
            renderer.raw += rawCssRule;
        }
    }, config);

    if (renderer.client) {
        if (!renderer.sh)
            document.head.appendChild(renderer.sh = document.createElement('style'));

        if (process.env.NODE_ENV !== 'production') {
            renderer.sh.setAttribute('data-nano-css-dev', '');

            // Test style sheet used in DEV mode to test if .insetRule() would throw.
            renderer.shTest = document.createElement('style');
            renderer.shTest.setAttribute('data-nano-css-dev-tests', '');
            document.head.appendChild(renderer.shTest);
        }

        renderer.putRaw = function (rawCssRule) {
            // .insertRule() is faster than .appendChild(), that's why we use it in PROD.
            // But CSS injected using .insertRule() is not displayed in Chrome Devtools,
            // that's why we use .appendChild in DEV.
            if (process.env.NODE_ENV === 'production') {
                var sheet = renderer.sh.sheet;

                // Unknown pseudo-selectors will throw, this try/catch swallows all errors.
                try {
                    sheet.insertRule(rawCssRule, sheet.cssRules.length);
                // eslint-disable-next-line no-empty
                } catch (error) {}
            } else {
                // Test if .insertRule() works in dev mode. Unknown pseudo-selectors will throw when
                // .insertRule() is used, but .appendChild() will not throw.
                try {
                    renderer.shTest.sheet.insertRule(rawCssRule, renderer.shTest.sheet.cssRules.length);
                } catch (error) {
                    if (config.verbose) {
                        console.error(error);
                    }
                }

                // Insert pretty-printed CSS for dev mode.
                renderer.sh.appendChild(document.createTextNode(rawCssRule));
            }
        };
    }

    renderer.put = function (selector, decls, atrule) {
        var str = '';
        var prop, value;
        var postponed = [];

        for (prop in decls) {
            value = decls[prop];

            if ((value instanceof Object) && !(value instanceof Array)) {
                postponed.push(prop);
            } else {
                if ((process.env.NODE_ENV !== 'production') && !renderer.sourcemaps) {
                    str += '    ' + renderer.decl(prop, value, selector, atrule) + '\n';
                } else {
                    str += renderer.decl(prop, value, selector, atrule);
                }
            }
        }

        if (str) {
            if ((process.env.NODE_ENV !== 'production') && !renderer.sourcemaps) {
                str = '\n' + selector + ' {\n' + str + '}\n';
            } else {
                str = selector + '{' + str + '}';
            }
            renderer.putRaw(atrule ? atrule + '{' + str + '}' : str);
        }

        for (var i = 0; i < postponed.length; i++) {
            prop = postponed[i];

            if (prop[0] === '@' && prop !== '@font-face') {
                renderer.putAt(selector, decls[prop], prop);
            } else {
                renderer.put(renderer.selector(selector, prop), decls[prop], atrule);
            }
        }
    };

    renderer.putAt = renderer.put;

    return renderer;
};