/*
	pseudo selectors

	---

	they are available in two forms:
	* filters called when the selector
	  is compiled and return a function
	  that needs to return next()
	* pseudos get called on execution
	  they need to return a boolean
*/

var getNCheck = require("nth-check");
var BaseFuncs = require("boolbase");
var attributes = require("./attributes.js");
var trueFunc = BaseFuncs.trueFunc;
var falseFunc = BaseFuncs.falseFunc;

var checkAttrib = attributes.rules.equals;

function getAttribFunc(name, value) {
    var data = { name: name, value: value };
    return function attribFunc(next, rule, options) {
        return checkAttrib(next, data, options);
    };
}

function getChildFunc(next, adapter) {
    return function(elem) {
        return !!adapter.getParent(elem) && next(elem);
    };
}

var filters = {
    contains: function(next, text, options) {
        var adapter = options.adapter;

        return function contains(elem) {
            return next(elem) && adapter.getText(elem).indexOf(text) >= 0;
        };
    },
    icontains: function(next, text, options) {
        var itext = text.toLowerCase();
        var adapter = options.adapter;

        return function icontains(elem) {
            return (
                next(elem) &&
                adapter
                    .getText(elem)
                    .toLowerCase()
                    .indexOf(itext) >= 0
            );
        };
    },

    //location specific methods
    "nth-child": function(next, rule, options) {
        var func = getNCheck(rule);
        var adapter = options.adapter;

        if (func === falseFunc) return func;
        if (func === trueFunc) return getChildFunc(next, adapter);

        return function nthChild(elem) {
            var siblings = adapter.getSiblings(elem);

            for (var i = 0, pos = 0; i < siblings.length; i++) {
                if (adapter.isTag(siblings[i])) {
                    if (siblings[i] === elem) break;
                    else pos++;
                }
            }

            return func(pos) && next(elem);
        };
    },
    "nth-last-child": function(next, rule, options) {
        var func = getNCheck(rule);
        var adapter = options.adapter;

        if (func === falseFunc) return func;
        if (func === trueFunc) return getChildFunc(next, adapter);

        return function nthLastChild(elem) {
            var siblings = adapter.getSiblings(elem);

            for (var pos = 0, i = siblings.length - 1; i >= 0; i--) {
                if (adapter.isTag(siblings[i])) {
                    if (siblings[i] === elem) break;
                    else pos++;
                }
            }

            return func(pos) && next(elem);
        };
    },
    "nth-of-type": function(next, rule, options) {
        var func = getNCheck(rule);
        var adapter = options.adapter;

        if (func === falseFunc) return func;
        if (func === trueFunc) return getChildFunc(next, adapter);

        return function nthOfType(elem) {
            var siblings = adapter.getSiblings(elem);

            for (var pos = 0, i = 0; i < siblings.length; i++) {
                if (adapter.isTag(siblings[i])) {
                    if (siblings[i] === elem) break;
                    if (adapter.getName(siblings[i]) === adapter.getName(elem)) pos++;
                }
            }

            return func(pos) && next(elem);
        };
    },
    "nth-last-of-type": function(next, rule, options) {
        var func = getNCheck(rule);
        var adapter = options.adapter;

        if (func === falseFunc) return func;
        if (func === trueFunc) return getChildFunc(next, adapter);

        return function nthLastOfType(elem) {
            var siblings = adapter.getSiblings(elem);

            for (var pos = 0, i = siblings.length - 1; i >= 0; i--) {
                if (adapter.isTag(siblings[i])) {
                    if (siblings[i] === elem) break;
                    if (adapter.getName(siblings[i]) === adapter.getName(elem)) pos++;
                }
            }

            return func(pos) && next(elem);
        };
    },

    //TODO determine the actual root element
    root: function(next, rule, options) {
        var adapter = options.adapter;

        return function(elem) {
            return !adapter.getParent(elem) && next(elem);
        };
    },

    scope: function(next, rule, options, context) {
        var adapter = options.adapter;

        if (!context || context.length === 0) {
            //equivalent to :root
            return filters.root(next, rule, options);
        }

        function equals(a, b) {
            if (typeof adapter.equals === "function") return adapter.equals(a, b);

            return a === b;
        }

        if (context.length === 1) {
            //NOTE: can't be unpacked, as :has uses this for side-effects
            return function(elem) {
                return equals(context[0], elem) && next(elem);
            };
        }

        return function(elem) {
            return context.indexOf(elem) >= 0 && next(elem);
        };
    },

    //jQuery extensions (others follow as pseudos)
    checkbox: getAttribFunc("type", "checkbox"),
    file: getAttribFunc("type", "file"),
    password: getAttribFunc("type", "password"),
    radio: getAttribFunc("type", "radio"),
    reset: getAttribFunc("type", "reset"),
    image: getAttribFunc("type", "image"),
    submit: getAttribFunc("type", "submit")
};

//helper methods
function getFirstElement(elems, adapter) {
    for (var i = 0; elems && i < elems.length; i++) {
        if (adapter.isTag(elems[i])) return elems[i];
    }
}

//while filters are precompiled, pseudos get called when they are needed
var pseudos = {
    empty: function(elem, adapter) {
        return !adapter.getChildren(elem).some(function(elem) {
            return adapter.isTag(elem) || elem.type === "text";
        });
    },

    "first-child": function(elem, adapter) {
        return getFirstElement(adapter.getSiblings(elem), adapter) === elem;
    },
    "last-child": function(elem, adapter) {
        var siblings = adapter.getSiblings(elem);

        for (var i = siblings.length - 1; i >= 0; i--) {
            if (siblings[i] === elem) return true;
            if (adapter.isTag(siblings[i])) break;
        }

        return false;
    },
    "first-of-type": function(elem, adapter) {
        var siblings = adapter.getSiblings(elem);

        for (var i = 0; i < siblings.length; i++) {
            if (adapter.isTag(siblings[i])) {
                if (siblings[i] === elem) return true;
                if (adapter.getName(siblings[i]) === adapter.getName(elem)) break;
            }
        }

        return false;
    },
    "last-of-type": function(elem, adapter) {
        var siblings = adapter.getSiblings(elem);

        for (var i = siblings.length - 1; i >= 0; i--) {
            if (adapter.isTag(siblings[i])) {
                if (siblings[i] === elem) return true;
                if (adapter.getName(siblings[i]) === adapter.getName(elem)) break;
            }
        }

        return false;
    },
    "only-of-type": function(elem, adapter) {
        var siblings = adapter.getSiblings(elem);

        for (var i = 0, j = siblings.length; i < j; i++) {
            if (adapter.isTag(siblings[i])) {
                if (siblings[i] === elem) continue;
                if (adapter.getName(siblings[i]) === adapter.getName(elem)) {
                    return false;
                }
            }
        }

        return true;
    },
    "only-child": function(elem, adapter) {
        var siblings = adapter.getSiblings(elem);

        for (var i = 0; i < siblings.length; i++) {
            if (adapter.isTag(siblings[i]) && siblings[i] !== elem) return false;
        }

        return true;
    },

    //:matches(a, area, link)[href]
    link: function(elem, adapter) {
        return adapter.hasAttrib(elem, "href");
    },
    visited: falseFunc, //Valid implementation
    //TODO: :any-link once the name is finalized (as an alias of :link)

    //forms
    //to consider: :target

    //:matches([selected], select:not([multiple]):not(> option[selected]) > option:first-of-type)
    selected: function(elem, adapter) {
        if (adapter.hasAttrib(elem, "selected")) return true;
        else if (adapter.getName(elem) !== "option") return false;

        //the first <option> in a <select> is also selected
        var parent = adapter.getParent(elem);

        if (!parent || adapter.getName(parent) !== "select" || adapter.hasAttrib(parent, "multiple")) {
            return false;
        }

        var siblings = adapter.getChildren(parent);
        var sawElem = false;

        for (var i = 0; i < siblings.length; i++) {
            if (adapter.isTag(siblings[i])) {
                if (siblings[i] === elem) {
                    sawElem = true;
                } else if (!sawElem) {
                    return false;
                } else if (adapter.hasAttrib(siblings[i], "selected")) {
                    return false;
                }
            }
        }

        return sawElem;
    },
    //https://html.spec.whatwg.org/multipage/scripting.html#disabled-elements
    //:matches(
    //  :matches(button, input, select, textarea, menuitem, optgroup, option)[disabled],
    //  optgroup[disabled] > option),
    // fieldset[disabled] * //TODO not child of first <legend>
    //)
    disabled: function(elem, adapter) {
        return adapter.hasAttrib(elem, "disabled");
    },
    enabled: function(elem, adapter) {
        return !adapter.hasAttrib(elem, "disabled");
    },
    //:matches(:matches(:radio, :checkbox)[checked], :selected) (TODO menuitem)
    checked: function(elem, adapter) {
        return adapter.hasAttrib(elem, "checked") || pseudos.selected(elem, adapter);
    },
    //:matches(input, select, textarea)[required]
    required: function(elem, adapter) {
        return adapter.hasAttrib(elem, "required");
    },
    //:matches(input, select, textarea):not([required])
    optional: function(elem, adapter) {
        return !adapter.hasAttrib(elem, "required");
    },

    //jQuery extensions

    //:not(:empty)
    parent: function(elem, adapter) {
        return !pseudos.empty(elem, adapter);
    },
    //:matches(h1, h2, h3, h4, h5, h6)
    header: namePseudo(["h1", "h2", "h3", "h4", "h5", "h6"]),

    //:matches(button, input[type=button])
    button: function(elem, adapter) {
        var name = adapter.getName(elem);
        return (
            name === "button" || (name === "input" && adapter.getAttributeValue(elem, "type") === "button")
        );
    },
    //:matches(input, textarea, select, button)
    input: namePseudo(["input", "textarea", "select", "button"]),
    //input:matches(:not([type!='']), [type='text' i])
    text: function(elem, adapter) {
        var attr;
        return (
            adapter.getName(elem) === "input" &&
            (!(attr = adapter.getAttributeValue(elem, "type")) || attr.toLowerCase() === "text")
        );
    }
};

function namePseudo(names) {
    if (typeof Set !== "undefined") {
        // eslint-disable-next-line no-undef
        var nameSet = new Set(names);

        return function(elem, adapter) {
            return nameSet.has(adapter.getName(elem));
        };
    }

    return function(elem, adapter) {
        return names.indexOf(adapter.getName(elem)) >= 0;
    };
}

function verifyArgs(func, name, subselect) {
    if (subselect === null) {
        if (func.length > 2 && name !== "scope") {
            throw new Error("pseudo-selector :" + name + " requires an argument");
        }
    } else {
        if (func.length === 2) {
            throw new Error("pseudo-selector :" + name + " doesn't have any arguments");
        }
    }
}

//FIXME this feels hacky
var re_CSS3 = /^(?:(?:nth|last|first|only)-(?:child|of-type)|root|empty|(?:en|dis)abled|checked|not)$/;

module.exports = {
    compile: function(next, data, options, context) {
        var name = data.name;
        var subselect = data.data;
        var adapter = options.adapter;

        if (options && options.strict && !re_CSS3.test(name)) {
            throw new Error(":" + name + " isn't part of CSS3");
        }

        if (typeof filters[name] === "function") {
            return filters[name](next, subselect, options, context);
        } else if (typeof pseudos[name] === "function") {
            var func = pseudos[name];
            verifyArgs(func, name, subselect);

            if (func === falseFunc) {
                return func;
            }

            if (next === trueFunc) {
                return function pseudoRoot(elem) {
                    return func(elem, adapter, subselect);
                };
            }

            return function pseudoArgs(elem) {
                return func(elem, adapter, subselect) && next(elem);
            };
        } else {
            throw new Error("unmatched pseudo-class :" + name);
        }
    },
    filters: filters,
    pseudos: pseudos
};
