import Testing
@testable import PureXML

@Suite("HTML5 foreign content (SVG/MathML namespaces)")
struct HTMLForeignContentTests {
    private let svg = "http://www.w3.org/2000/svg"
    private let mathml = "http://www.w3.org/1998/Math/MathML"

    /// The first element with the given local name in the parsed document.
    private func find(_ name: String, in html: String) -> PureXML.Model.Element? {
        find(name, in: PureXML.HTML.parseDocument(html))
    }

    private func find(_ name: String, in node: PureXML.Model.Node) -> PureXML.Model.Element? {
        switch node {
        case let .document(children):
            return children.lazy.compactMap { find(name, in: $0) }.first
        case let .element(element):
            if element.name.localName == name { return element }
            return element.children.lazy.compactMap { find(name, in: $0) }.first
        default:
            return nil
        }
    }

    @Test("An svg element and its descendants carry the SVG namespace")
    func test_svgNamespace() {
        let html = "<p><svg><g><rect></rect></g></svg></p>"
        #expect(find("svg", in: html)?.name.namespaceURI == svg)
        #expect(find("g", in: html)?.name.namespaceURI == svg)
        #expect(find("rect", in: html)?.name.namespaceURI == svg)
    }

    @Test("A math element and its descendants carry the MathML namespace")
    func test_mathmlNamespace() {
        let html = "<math><mi>x</mi></math>"
        #expect(find("math", in: html)?.name.namespaceURI == mathml)
        #expect(find("mi", in: html)?.name.namespaceURI == mathml)
    }

    @Test("Ordinary HTML elements have no namespace")
    func test_htmlNoNamespace() {
        #expect(find("p", in: "<p>text</p>")?.name.namespaceURI == nil)
    }

    @Test("HTML content after a closed svg is back in no namespace")
    func test_namespaceResumes() {
        let html = "<svg><rect></rect></svg><p>after</p>"
        #expect(find("rect", in: html)?.name.namespaceURI == svg)
        #expect(find("p", in: html)?.name.namespaceURI == nil)
    }

    @Test("SVG element names are restored to their canonical camel case")
    func test_svgNameCaseAdjustment() {
        let html = "<svg><foreignObject></foreignObject><lineargradient></lineargradient></svg>"
        #expect(find("foreignObject", in: html)?.name.namespaceURI == svg)
        #expect(find("linearGradient", in: html)?.name.namespaceURI == svg)
        // The lowercased forms the tokenizer produced are not what landed in the tree.
        #expect(find("foreignobject", in: html) == nil)
    }

    @Test("A same-named HTML element keeps its lowercased name")
    func test_htmlNameNotAdjusted() {
        // Outside SVG, no case adjustment applies.
        #expect(find("clippath", in: "<clippath></clippath>")?.name.namespaceURI == nil)
        #expect(find("clipPath", in: "<clippath></clippath>") == nil)
    }

    @Test("SVG attribute names are restored to their canonical camel case")
    func test_svgAttributeCase() {
        let rect = find("rect", in: "<svg><rect viewbox=\"0 0 1 1\" width=\"1\"></rect></svg>")
        #expect(rect?.attributes.contains { $0.name.description == "viewBox" } == true)
        #expect(rect?.attributes.contains { $0.name.description == "width" } == true)
        #expect(rect?.attributes.contains { $0.name.description == "viewbox" } == false)
    }

    @Test("HTML attribute names are not case-adjusted")
    func test_htmlAttributeNotAdjusted() {
        let element = find("p", in: "<p viewbox=\"x\"></p>")
        #expect(element?.attributes.contains { $0.name.description == "viewbox" } == true)
    }

    @Test("HTML content inside an SVG integration point is back in the HTML namespace")
    func test_integrationPoint() {
        let html = "<svg><foreignObject><div><span>x</span></div></foreignObject></svg>"
        #expect(find("foreignObject", in: html)?.name.namespaceURI == svg)
        #expect(find("div", in: html)?.name.namespaceURI == nil)
        #expect(find("span", in: html)?.name.namespaceURI == nil)
    }

    @Test("Re-entering svg inside an integration point switches back to SVG")
    func test_reentrantForeign() {
        let html = "<svg><foreignObject><svg><rect></rect></svg></foreignObject></svg>"
        #expect(find("rect", in: html)?.name.namespaceURI == svg)
    }
}