const std = @import("std");

const parser = @import("../netsurf.zig");

const jsruntime = @import("jsruntime");
const Case = jsruntime.test_utils.Case;
const checkCases = jsruntime.test_utils.checkCases;

const collection = @import("html_collection.zig");

const Node = @import("node.zig").Node;
const Walker = @import("html_collection.zig").WalkerDepthFirst;
const NodeList = @import("nodelist.zig").NodeList;
const HTMLElem = @import("../html/elements.zig");
pub const Union = @import("../html/elements.zig").Union;

const DOMException = @import("exceptions.zig").DOMException;

// WEB IDL https://dom.spec.whatwg.org/#element
pub const Element = struct {
    pub const Self = parser.Element;
    pub const prototype = *Node;
    pub const mem_guarantied = true;

    pub fn toInterface(e: *parser.Element) !Union {
        return try HTMLElem.toInterface(Union, e);
    }

    // JS funcs
    // --------

    pub fn get_namespaceURI(self: *parser.Element) !?[]const u8 {
        return try parser.nodeGetNamespace(parser.elementToNode(self));
    }

    pub fn get_prefix(self: *parser.Element) !?[]const u8 {
        return try parser.nodeGetPrefix(parser.elementToNode(self));
    }

    pub fn get_localName(self: *parser.Element) ![]const u8 {
        return try parser.nodeLocalName(parser.elementToNode(self));
    }

    pub fn get_tagName(self: *parser.Element) ![]const u8 {
        return try parser.nodeName(parser.elementToNode(self));
    }

    pub fn get_id(self: *parser.Element) ![]const u8 {
        return try parser.elementGetAttribute(self, "id") orelse "";
    }

    pub fn set_id(self: *parser.Element, id: []const u8) !void {
        return try parser.elementSetAttribute(self, "id", id);
    }

    pub fn get_className(self: *parser.Element) ![]const u8 {
        return try parser.elementGetAttribute(self, "class") orelse "";
    }

    pub fn set_className(self: *parser.Element, class: []const u8) !void {
        return try parser.elementSetAttribute(self, "class", class);
    }

    pub fn get_slot(self: *parser.Element) ![]const u8 {
        return try parser.elementGetAttribute(self, "slot") orelse "";
    }

    pub fn set_slot(self: *parser.Element, slot: []const u8) !void {
        return try parser.elementSetAttribute(self, "slot", slot);
    }

    pub fn get_classList(self: *parser.Element) !*parser.TokenList {
        return try parser.tokenListCreate(self, "class");
    }

    pub fn get_attributes(self: *parser.Element) !*parser.NamedNodeMap {
        return try parser.nodeGetAttributes(parser.elementToNode(self));
    }

    pub fn _hasAttributes(self: *parser.Element) !bool {
        return try parser.nodeHasAttributes(parser.elementToNode(self));
    }

    pub fn _getAttribute(self: *parser.Element, qname: []const u8) !?[]const u8 {
        return try parser.elementGetAttribute(self, qname);
    }

    pub fn _setAttribute(self: *parser.Element, qname: []const u8, value: []const u8) !void {
        return try parser.elementSetAttribute(self, qname, value);
    }

    pub fn _removeAttribute(self: *parser.Element, qname: []const u8) !void {
        return try parser.elementRemoveAttribute(self, qname);
    }

    pub fn _hasAttribute(self: *parser.Element, qname: []const u8) !bool {
        return try parser.elementHasAttribute(self, qname);
    }

    // https://dom.spec.whatwg.org/#dom-element-toggleattribute
    pub fn _toggleAttribute(self: *parser.Element, qname: []const u8, force: ?bool) !bool {
        const exists = try parser.elementHasAttribute(self, qname);

        // If attribute is null, then:
        if (!exists) {
            // If force is not given or is true, create an attribute whose
            // local name is qualifiedName, value is the empty string and node
            // document is this’s node document, then append this attribute to
            // this, and then return true.
            if (force == null or force.?) {
                try parser.elementSetAttribute(self, qname, "");
                return true;
            }

            // Return false.
            return false;
        }

        // Otherwise, if force is not given or is false, remove an attribute
        // given qualifiedName and this, and then return false.
        if (force == null or !force.?) {
            try parser.elementRemoveAttribute(self, qname);
            return false;
        }

        // Return true.
        return true;
    }

    pub fn _getAttributeNode(self: *parser.Element, name: []const u8) !?*parser.Attribute {
        return try parser.elementGetAttributeNode(self, name);
    }

    pub fn _getAttributeNodeNS(self: *parser.Element, ns: []const u8, name: []const u8) !?*parser.Attribute {
        return try parser.elementGetAttributeNodeNS(self, ns, name);
    }

    pub fn _setAttributeNode(self: *parser.Element, attr: *parser.Attribute) !?*parser.Attribute {
        return try parser.elementSetAttributeNode(self, attr);
    }

    pub fn _setAttributeNodeNS(self: *parser.Element, attr: *parser.Attribute) !?*parser.Attribute {
        return try parser.elementSetAttributeNodeNS(self, attr);
    }

    pub fn _removeAttributeNode(self: *parser.Element, attr: *parser.Attribute) !*parser.Attribute {
        return try parser.elementRemoveAttributeNode(self, attr);
    }

    pub fn _getElementsByTagName(
        self: *parser.Element,
        alloc: std.mem.Allocator,
        tag_name: []const u8,
    ) !collection.HTMLCollection {
        return try collection.HTMLCollectionByTagName(
            alloc,
            parser.elementToNode(self),
            tag_name,
            false,
        );
    }

    pub fn _getElementsByClassName(
        self: *parser.Element,
        alloc: std.mem.Allocator,
        classNames: []const u8,
    ) !collection.HTMLCollection {
        return try collection.HTMLCollectionByClassName(
            alloc,
            parser.elementToNode(self),
            classNames,
            false,
        );
    }

    // ParentNode
    // https://dom.spec.whatwg.org/#parentnode
    pub fn get_children(self: *parser.Element) !collection.HTMLCollection {
        return try collection.HTMLCollectionChildren(parser.elementToNode(self), false);
    }

    pub fn get_firstElementChild(self: *parser.Element) !?Union {
        var children = try get_children(self);
        return try children._item(0);
    }

    pub fn get_lastElementChild(self: *parser.Element) !?Union {
        // TODO we could check the last child node first, if it's an element,
        // we can return it directly instead of looping twice over the
        // children.
        var children = try get_children(self);
        const ln = try children.get_length();
        if (ln == 0) return null;
        return try children._item(ln - 1);
    }

    pub fn get_childElementCount(self: *parser.Element) !u32 {
        var children = try get_children(self);
        return try children.get_length();
    }

    // NonDocumentTypeChildNode
    // https://dom.spec.whatwg.org/#interface-nondocumenttypechildnode
    pub fn get_previousElementSibling(self: *parser.Element) !?Union {
        const res = try parser.nodePreviousElementSibling(parser.elementToNode(self));
        if (res == null) return null;
        return try HTMLElem.toInterface(HTMLElem.Union, res.?);
    }

    pub fn get_nextElementSibling(self: *parser.Element) !?Union {
        const res = try parser.nodeNextElementSibling(parser.elementToNode(self));
        if (res == null) return null;
        return try HTMLElem.toInterface(HTMLElem.Union, res.?);
    }

    fn getElementById(self: *parser.Element, id: []const u8) !?*parser.Node {
        // walk over the node tree fo find the node by id.
        const root = parser.elementToNode(self);
        const walker = Walker{};
        var next: ?*parser.Node = null;
        while (true) {
            next = try walker.get_next(root, next) orelse return null;
            // ignore non-element nodes.
            if (try parser.nodeType(next.?) != .element) {
                continue;
            }
            const e = parser.nodeToElement(next.?);
            if (std.mem.eql(u8, id, try get_id(e))) return next;
        }
    }

    // TODO netsurf doesn't handle query selectors. We have to implement a
    // solution by ourselves.
    // We handle only * and single id selector like `#foo`.
    pub fn _querySelector(self: *parser.Element, selectors: []const u8) !?Union {
        if (selectors.len == 0) return null;

        // catch-all, return the firstElementChild
        if (selectors[0] == '*') return try get_firstElementChild(self);

        // support only simple id selector.
        if (selectors[0] != '#' or std.mem.indexOf(u8, selectors, " ") != null) return null;

        // walk over the node tree fo find the node by id.
        const n = try getElementById(self, selectors[1..]) orelse return null;
        return try toInterface(parser.nodeToElement(n));
    }

    // TODO netsurf doesn't handle query selectors. We have to implement a
    // solution by ourselves.
    // We handle only * and single id selector like `#foo`.
    pub fn _querySelectorAll(self: *parser.Element, alloc: std.mem.Allocator, selectors: []const u8) !NodeList {
        var list = try NodeList.init();
        errdefer list.deinit(alloc);

        if (selectors.len == 0) return list;

        // catch-all, return all elements
        if (selectors[0] == '*') {
            // walk over the node tree fo find the node by id.
            const root = parser.elementToNode(self);
            const walker = Walker{};
            var next: ?*parser.Node = null;
            while (true) {
                next = try walker.get_next(root, next) orelse return list;
                // ignore non-element nodes.
                if (try parser.nodeType(next.?) != .element) {
                    continue;
                }
                try list.append(alloc, next.?);
            }
        }

        // support only simple id selector.
        if (selectors[0] != '#' or std.mem.indexOf(u8, selectors, " ") != null) return list;

        // walk over the node tree fo find the node by id.
        const n = try getElementById(self, selectors[1..]) orelse return list;
        try list.append(alloc, n);

        return list;
    }

    pub fn deinit(_: *parser.Element, _: std.mem.Allocator) void {}
};

// Tests
// -----

pub fn testExecFn(
    _: std.mem.Allocator,
    js_env: *jsruntime.Env,
    comptime _: []jsruntime.API,
) !void {
    var getters = [_]Case{
        .{ .src = "let g = document.getElementById('content')", .ex = "undefined" },
        .{ .src = "g.namespaceURI", .ex = "http://www.w3.org/1999/xhtml" },
        .{ .src = "g.prefix", .ex = "null" },
        .{ .src = "g.localName", .ex = "div" },
        .{ .src = "g.tagName", .ex = "DIV" },
    };
    try checkCases(js_env, &getters);

    var gettersetters = [_]Case{
        .{ .src = "let gs = document.getElementById('content')", .ex = "undefined" },
        .{ .src = "gs.id", .ex = "content" },
        .{ .src = "gs.id = 'foo'", .ex = "foo" },
        .{ .src = "gs.id", .ex = "foo" },
        .{ .src = "gs.id = 'content'", .ex = "content" },
        .{ .src = "gs.className", .ex = "" },
        .{ .src = "let gs2 = document.getElementById('para-empty')", .ex = "undefined" },
        .{ .src = "gs2.className", .ex = "ok empty" },
        .{ .src = "gs2.className = 'foo bar baz'", .ex = "foo bar baz" },
        .{ .src = "gs2.className", .ex = "foo bar baz" },
        .{ .src = "gs2.className = 'ok empty'", .ex = "ok empty" },
        .{ .src = "let cl = gs2.classList", .ex = "undefined" },
        .{ .src = "cl.length", .ex = "2" },
    };
    try checkCases(js_env, &gettersetters);

    var attribute = [_]Case{
        .{ .src = "let a = document.getElementById('content')", .ex = "undefined" },
        .{ .src = "a.hasAttributes()", .ex = "true" },
        .{ .src = "a.attributes.length", .ex = "1" },

        .{ .src = "a.getAttribute('id')", .ex = "content" },

        .{ .src = "a.hasAttribute('foo')", .ex = "false" },
        .{ .src = "a.getAttribute('foo')", .ex = "null" },

        .{ .src = "a.setAttribute('foo', 'bar')", .ex = "undefined" },
        .{ .src = "a.hasAttribute('foo')", .ex = "true" },
        .{ .src = "a.getAttribute('foo')", .ex = "bar" },

        .{ .src = "a.setAttribute('foo', 'baz')", .ex = "undefined" },
        .{ .src = "a.hasAttribute('foo')", .ex = "true" },
        .{ .src = "a.getAttribute('foo')", .ex = "baz" },

        .{ .src = "a.removeAttribute('foo')", .ex = "undefined" },
        .{ .src = "a.hasAttribute('foo')", .ex = "false" },
        .{ .src = "a.getAttribute('foo')", .ex = "null" },
    };
    try checkCases(js_env, &attribute);

    var toggleAttr = [_]Case{
        .{ .src = "let b = document.getElementById('content')", .ex = "undefined" },
        .{ .src = "b.toggleAttribute('foo')", .ex = "true" },
        .{ .src = "b.hasAttribute('foo')", .ex = "true" },
        .{ .src = "b.getAttribute('foo')", .ex = "" },

        .{ .src = "b.toggleAttribute('foo')", .ex = "false" },
        .{ .src = "b.hasAttribute('foo')", .ex = "false" },
    };
    try checkCases(js_env, &toggleAttr);

    var parentNode = [_]Case{
        .{ .src = "let c = document.getElementById('content')", .ex = "undefined" },
        .{ .src = "c.children.length", .ex = "3" },
        .{ .src = "c.firstElementChild.nodeName", .ex = "A" },
        .{ .src = "c.lastElementChild.nodeName", .ex = "P" },
        .{ .src = "c.childElementCount", .ex = "3" },
    };
    try checkCases(js_env, &parentNode);

    var elementSibling = [_]Case{
        .{ .src = "let d = document.getElementById('para')", .ex = "undefined" },
        .{ .src = "d.previousElementSibling.nodeName", .ex = "P" },
        .{ .src = "d.nextElementSibling", .ex = "null" },
    };
    try checkCases(js_env, &elementSibling);

    var querySelector = [_]Case{
        .{ .src = "let e = document.getElementById('content')", .ex = "undefined" },
        .{ .src = "e.querySelector('foo')", .ex = "null" },
        .{ .src = "e.querySelector('#foo')", .ex = "null" },
        .{ .src = "e.querySelector('#link').id", .ex = "link" },
        .{ .src = "e.querySelector('#para').id", .ex = "para" },
        .{ .src = "e.querySelector('*').id", .ex = "link" },

        .{ .src = "e.querySelectorAll('foo').length", .ex = "0" },
        .{ .src = "e.querySelectorAll('#foo').length", .ex = "0" },
        .{ .src = "e.querySelectorAll('#link').length", .ex = "1" },
        .{ .src = "e.querySelectorAll('#link').item(0).id", .ex = "link" },
        .{ .src = "e.querySelectorAll('#para').length", .ex = "1" },
        .{ .src = "e.querySelectorAll('#para').item(0).id", .ex = "para" },
        .{ .src = "e.querySelectorAll('*').length", .ex = "4" },
    };
    try checkCases(js_env, &querySelector);

    var attrNode = [_]Case{
        .{ .src = "let f = document.getElementById('content')", .ex = "undefined" },
        .{ .src = "let ff = document.createAttribute('foo')", .ex = "undefined" },
        .{ .src = "f.setAttributeNode(ff)", .ex = "null" },
        .{ .src = "f.getAttributeNode('foo').name", .ex = "foo" },
        .{ .src = "f.removeAttributeNode(ff).name", .ex = "foo" },
        .{ .src = "f.getAttributeNode('bar')", .ex = "null" },
    };
    try checkCases(js_env, &attrNode);
}