/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

use std::default::Default;
use std::iter;

use dom_struct::dom_struct;
use html5ever::{local_name, LocalName, Prefix};
use js::rust::HandleObject;
use style::attr::AttrValue;
use style_traits::dom::ElementState;

use crate::dom::attr::Attr;
use crate::dom::bindings::codegen::Bindings::ElementBinding::ElementMethods;
use crate::dom::bindings::codegen::Bindings::HTMLCollectionBinding::HTMLCollectionMethods;
use crate::dom::bindings::codegen::Bindings::HTMLOptionElementBinding::HTMLOptionElementMethods;
use crate::dom::bindings::codegen::Bindings::HTMLOptionsCollectionBinding::HTMLOptionsCollectionMethods;
use crate::dom::bindings::codegen::Bindings::HTMLSelectElementBinding::HTMLSelectElementMethods;
use crate::dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
use crate::dom::bindings::codegen::UnionTypes::{
    HTMLElementOrLong, HTMLOptionElementOrHTMLOptGroupElement,
};
use crate::dom::bindings::error::ErrorResult;
use crate::dom::bindings::inheritance::Castable;
use crate::dom::bindings::root::{DomRoot, MutNullableDom};
use crate::dom::bindings::str::DOMString;
use crate::dom::document::Document;
use crate::dom::element::{AttributeMutation, Element};
use crate::dom::htmlcollection::CollectionFilter;
use crate::dom::htmlelement::HTMLElement;
use crate::dom::htmlfieldsetelement::HTMLFieldSetElement;
use crate::dom::htmlformelement::{FormControl, FormDatum, FormDatumValue, HTMLFormElement};
use crate::dom::htmloptgroupelement::HTMLOptGroupElement;
use crate::dom::htmloptionelement::HTMLOptionElement;
use crate::dom::htmloptionscollection::HTMLOptionsCollection;
use crate::dom::node::{window_from_node, BindContext, Node, UnbindContext};
use crate::dom::nodelist::NodeList;
use crate::dom::validation::{is_barred_by_datalist_ancestor, Validatable};
use crate::dom::validitystate::{ValidationFlags, ValidityState};
use crate::dom::virtualmethods::VirtualMethods;

#[derive(JSTraceable, MallocSizeOf)]
struct OptionsFilter;
impl CollectionFilter for OptionsFilter {
    fn filter<'a>(&self, elem: &'a Element, root: &'a Node) -> bool {
        if !elem.is::<HTMLOptionElement>() {
            return false;
        }

        let node = elem.upcast::<Node>();
        if root.is_parent_of(node) {
            return true;
        }

        match node.GetParentNode() {
            Some(optgroup) => optgroup.is::<HTMLOptGroupElement>() && root.is_parent_of(&optgroup),
            None => false,
        }
    }
}

#[dom_struct]
pub struct HTMLSelectElement {
    htmlelement: HTMLElement,
    options: MutNullableDom<HTMLOptionsCollection>,
    form_owner: MutNullableDom<HTMLFormElement>,
    labels_node_list: MutNullableDom<NodeList>,
    validity_state: MutNullableDom<ValidityState>,
}

static DEFAULT_SELECT_SIZE: u32 = 0;

impl HTMLSelectElement {
    fn new_inherited(
        local_name: LocalName,
        prefix: Option<Prefix>,
        document: &Document,
    ) -> HTMLSelectElement {
        HTMLSelectElement {
            htmlelement: HTMLElement::new_inherited_with_state(
                ElementState::ENABLED | ElementState::VALID,
                local_name,
                prefix,
                document,
            ),
            options: Default::default(),
            form_owner: Default::default(),
            labels_node_list: Default::default(),
            validity_state: Default::default(),
        }
    }

    #[allow(crown::unrooted_must_root)]
    pub fn new(
        local_name: LocalName,
        prefix: Option<Prefix>,
        document: &Document,
        proto: Option<HandleObject>,
    ) -> DomRoot<HTMLSelectElement> {
        let n = Node::reflect_node_with_proto(
            Box::new(HTMLSelectElement::new_inherited(
                local_name, prefix, document,
            )),
            document,
            proto,
        );

        n.upcast::<Node>().set_weird_parser_insertion_mode();
        n
    }

    // https://html.spec.whatwg.org/multipage/#concept-select-option-list
    pub fn list_of_options(&self) -> impl Iterator<Item = DomRoot<HTMLOptionElement>> {
        self.upcast::<Node>().children().flat_map(|node| {
            if node.is::<HTMLOptionElement>() {
                let node = DomRoot::downcast::<HTMLOptionElement>(node).unwrap();
                Choice3::First(iter::once(node))
            } else if node.is::<HTMLOptGroupElement>() {
                Choice3::Second(node.children().filter_map(DomRoot::downcast))
            } else {
                Choice3::Third(iter::empty())
            }
        })
    }

    // https://html.spec.whatwg.org/multipage/#placeholder-label-option
    fn get_placeholder_label_option(&self) -> Option<DomRoot<HTMLOptionElement>> {
        if self.Required() && !self.Multiple() && self.display_size() == 1 {
            self.list_of_options().next().filter(|node| {
                let parent = node.upcast::<Node>().GetParentNode();
                node.Value().is_empty() && parent.as_deref() == Some(self.upcast())
            })
        } else {
            None
        }
    }

    // https://html.spec.whatwg.org/multipage/#the-select-element:concept-form-reset-control
    pub fn reset(&self) {
        for opt in self.list_of_options() {
            opt.set_selectedness(opt.DefaultSelected());
            opt.set_dirtiness(false);
        }
        self.ask_for_reset();
    }

    // https://html.spec.whatwg.org/multipage/#ask-for-a-reset
    pub fn ask_for_reset(&self) {
        if self.Multiple() {
            return;
        }

        let mut first_enabled: Option<DomRoot<HTMLOptionElement>> = None;
        let mut last_selected: Option<DomRoot<HTMLOptionElement>> = None;

        for opt in self.list_of_options() {
            if opt.Selected() {
                opt.set_selectedness(false);
                last_selected = Some(DomRoot::from_ref(&opt));
            }
            let element = opt.upcast::<Element>();
            if first_enabled.is_none() && !element.disabled_state() {
                first_enabled = Some(DomRoot::from_ref(&opt));
            }
        }

        if let Some(last_selected) = last_selected {
            last_selected.set_selectedness(true);
        } else if self.display_size() == 1 {
            if let Some(first_enabled) = first_enabled {
                first_enabled.set_selectedness(true);
            }
        }
    }

    pub fn push_form_data(&self, data_set: &mut Vec<FormDatum>) {
        if self.Name().is_empty() {
            return;
        }
        for opt in self.list_of_options() {
            let element = opt.upcast::<Element>();
            if opt.Selected() && element.enabled_state() {
                data_set.push(FormDatum {
                    ty: self.Type(),
                    name: self.Name(),
                    value: FormDatumValue::String(opt.Value()),
                });
            }
        }
    }

    // https://html.spec.whatwg.org/multipage/#concept-select-pick
    pub fn pick_option(&self, picked: &HTMLOptionElement) {
        if !self.Multiple() {
            let picked = picked.upcast();
            for opt in self.list_of_options() {
                if opt.upcast::<HTMLElement>() != picked {
                    opt.set_selectedness(false);
                }
            }
        }
    }

    // https://html.spec.whatwg.org/multipage/#concept-select-size
    fn display_size(&self) -> u32 {
        if self.Size() == 0 {
            if self.Multiple() {
                4
            } else {
                1
            }
        } else {
            self.Size()
        }
    }
}

impl HTMLSelectElementMethods for HTMLSelectElement {
    // https://html.spec.whatwg.org/multipage/#dom-select-add
    fn Add(
        &self,
        element: HTMLOptionElementOrHTMLOptGroupElement,
        before: Option<HTMLElementOrLong>,
    ) -> ErrorResult {
        self.Options().Add(element, before)
    }

    // https://html.spec.whatwg.org/multipage/#dom-fe-disabled
    make_bool_getter!(Disabled, "disabled");

    // https://html.spec.whatwg.org/multipage/#dom-fe-disabled
    make_bool_setter!(SetDisabled, "disabled");

    // https://html.spec.whatwg.org/multipage/#dom-fae-form
    fn GetForm(&self) -> Option<DomRoot<HTMLFormElement>> {
        self.form_owner()
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-multiple
    make_bool_getter!(Multiple, "multiple");

    // https://html.spec.whatwg.org/multipage/#dom-select-multiple
    make_bool_setter!(SetMultiple, "multiple");

    // https://html.spec.whatwg.org/multipage/#dom-fe-name
    make_getter!(Name, "name");

    // https://html.spec.whatwg.org/multipage/#dom-fe-name
    make_atomic_setter!(SetName, "name");

    // https://html.spec.whatwg.org/multipage/#dom-select-required
    make_bool_getter!(Required, "required");

    // https://html.spec.whatwg.org/multipage/#dom-select-required
    make_bool_setter!(SetRequired, "required");

    // https://html.spec.whatwg.org/multipage/#dom-select-size
    make_uint_getter!(Size, "size", DEFAULT_SELECT_SIZE);

    // https://html.spec.whatwg.org/multipage/#dom-select-size
    make_uint_setter!(SetSize, "size", DEFAULT_SELECT_SIZE);

    // https://html.spec.whatwg.org/multipage/#dom-select-type
    fn Type(&self) -> DOMString {
        DOMString::from(if self.Multiple() {
            "select-multiple"
        } else {
            "select-one"
        })
    }

    // https://html.spec.whatwg.org/multipage/#dom-lfe-labels
    make_labels_getter!(Labels, labels_node_list);

    // https://html.spec.whatwg.org/multipage/#dom-select-options
    fn Options(&self) -> DomRoot<HTMLOptionsCollection> {
        self.options.or_init(|| {
            let window = window_from_node(self);
            HTMLOptionsCollection::new(&window, self, Box::new(OptionsFilter))
        })
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-length
    fn Length(&self) -> u32 {
        self.Options().Length()
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-length
    fn SetLength(&self, length: u32) {
        self.Options().SetLength(length)
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-item
    fn Item(&self, index: u32) -> Option<DomRoot<Element>> {
        self.Options().upcast().Item(index)
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-item
    fn IndexedGetter(&self, index: u32) -> Option<DomRoot<Element>> {
        self.Options().IndexedGetter(index)
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-setter
    fn IndexedSetter(&self, index: u32, value: Option<&HTMLOptionElement>) -> ErrorResult {
        self.Options().IndexedSetter(index, value)
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-nameditem
    fn NamedItem(&self, name: DOMString) -> Option<DomRoot<HTMLOptionElement>> {
        self.Options()
            .NamedGetter(name)
            .and_then(DomRoot::downcast::<HTMLOptionElement>)
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-remove
    fn Remove_(&self, index: i32) {
        self.Options().Remove(index)
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-remove
    fn Remove(&self) {
        self.upcast::<Element>().Remove()
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-value
    fn Value(&self) -> DOMString {
        self.list_of_options()
            .filter(|opt_elem| opt_elem.Selected())
            .map(|opt_elem| opt_elem.Value())
            .next()
            .unwrap_or_default()
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-value
    fn SetValue(&self, value: DOMString) {
        let mut opt_iter = self.list_of_options();
        // Reset until we find an <option> with a matching value
        for opt in opt_iter.by_ref() {
            if opt.Value() == value {
                opt.set_selectedness(true);
                opt.set_dirtiness(true);
                break;
            }
            opt.set_selectedness(false);
        }
        // Reset remaining <option> elements
        for opt in opt_iter {
            opt.set_selectedness(false);
        }

        self.validity_state()
            .perform_validation_and_update(ValidationFlags::VALUE_MISSING);
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-selectedindex
    fn SelectedIndex(&self) -> i32 {
        self.list_of_options()
            .enumerate()
            .filter(|(_, opt_elem)| opt_elem.Selected())
            .map(|(i, _)| i as i32)
            .next()
            .unwrap_or(-1)
    }

    // https://html.spec.whatwg.org/multipage/#dom-select-selectedindex
    fn SetSelectedIndex(&self, index: i32) {
        let mut opt_iter = self.list_of_options();
        for opt in opt_iter.by_ref().take(index as usize) {
            opt.set_selectedness(false);
        }
        if let Some(opt) = opt_iter.next() {
            opt.set_selectedness(true);
            opt.set_dirtiness(true);
            // Reset remaining <option> elements
            for opt in opt_iter {
                opt.set_selectedness(false);
            }
        }
    }

    // https://html.spec.whatwg.org/multipage/#dom-cva-willvalidate
    fn WillValidate(&self) -> bool {
        self.is_instance_validatable()
    }

    // https://html.spec.whatwg.org/multipage/#dom-cva-validity
    fn Validity(&self) -> DomRoot<ValidityState> {
        self.validity_state()
    }

    // https://html.spec.whatwg.org/multipage/#dom-cva-checkvalidity
    fn CheckValidity(&self) -> bool {
        self.check_validity()
    }

    // https://html.spec.whatwg.org/multipage/#dom-cva-reportvalidity
    fn ReportValidity(&self) -> bool {
        self.report_validity()
    }

    // https://html.spec.whatwg.org/multipage/#dom-cva-validationmessage
    fn ValidationMessage(&self) -> DOMString {
        self.validation_message()
    }

    // https://html.spec.whatwg.org/multipage/#dom-cva-setcustomvalidity
    fn SetCustomValidity(&self, error: DOMString) {
        self.validity_state().set_custom_error_message(error);
    }
}

impl VirtualMethods for HTMLSelectElement {
    fn super_type(&self) -> Option<&dyn VirtualMethods> {
        Some(self.upcast::<HTMLElement>() as &dyn VirtualMethods)
    }

    fn attribute_mutated(&self, attr: &Attr, mutation: AttributeMutation) {
        self.super_type().unwrap().attribute_mutated(attr, mutation);
        match *attr.local_name() {
            local_name!("required") => {
                self.validity_state()
                    .perform_validation_and_update(ValidationFlags::VALUE_MISSING);
            },
            local_name!("disabled") => {
                let el = self.upcast::<Element>();
                match mutation {
                    AttributeMutation::Set(_) => {
                        el.set_disabled_state(true);
                        el.set_enabled_state(false);
                    },
                    AttributeMutation::Removed => {
                        el.set_disabled_state(false);
                        el.set_enabled_state(true);
                        el.check_ancestors_disabled_state_for_form_control();
                    },
                }

                self.validity_state()
                    .perform_validation_and_update(ValidationFlags::VALUE_MISSING);
            },
            local_name!("form") => {
                self.form_attribute_mutated(mutation);
            },
            _ => {},
        }
    }

    fn bind_to_tree(&self, context: &BindContext) {
        if let Some(s) = self.super_type() {
            s.bind_to_tree(context);
        }

        self.upcast::<Element>()
            .check_ancestors_disabled_state_for_form_control();
    }

    fn unbind_from_tree(&self, context: &UnbindContext) {
        self.super_type().unwrap().unbind_from_tree(context);

        let node = self.upcast::<Node>();
        let el = self.upcast::<Element>();
        if node
            .ancestors()
            .any(|ancestor| ancestor.is::<HTMLFieldSetElement>())
        {
            el.check_ancestors_disabled_state_for_form_control();
        } else {
            el.check_disabled_attribute();
        }
    }

    fn parse_plain_attribute(&self, local_name: &LocalName, value: DOMString) -> AttrValue {
        match *local_name {
            local_name!("size") => AttrValue::from_u32(value.into(), DEFAULT_SELECT_SIZE),
            _ => self
                .super_type()
                .unwrap()
                .parse_plain_attribute(local_name, value),
        }
    }
}

impl FormControl for HTMLSelectElement {
    fn form_owner(&self) -> Option<DomRoot<HTMLFormElement>> {
        self.form_owner.get()
    }

    fn set_form_owner(&self, form: Option<&HTMLFormElement>) {
        self.form_owner.set(form);
    }

    fn to_element(&self) -> &Element {
        self.upcast::<Element>()
    }
}

impl Validatable for HTMLSelectElement {
    fn as_element(&self) -> &Element {
        self.upcast()
    }

    fn validity_state(&self) -> DomRoot<ValidityState> {
        self.validity_state
            .or_init(|| ValidityState::new(&window_from_node(self), self.upcast()))
    }

    fn is_instance_validatable(&self) -> bool {
        // https://html.spec.whatwg.org/multipage/#enabling-and-disabling-form-controls%3A-the-disabled-attribute%3Abarred-from-constraint-validation
        // https://html.spec.whatwg.org/multipage/#the-datalist-element%3Abarred-from-constraint-validation
        !self.upcast::<Element>().disabled_state() && !is_barred_by_datalist_ancestor(self.upcast())
    }

    fn perform_validation(&self, validate_flags: ValidationFlags) -> ValidationFlags {
        let mut failed_flags = ValidationFlags::empty();

        // https://html.spec.whatwg.org/multipage/#suffering-from-being-missing
        // https://html.spec.whatwg.org/multipage/#the-select-element%3Asuffering-from-being-missing
        if validate_flags.contains(ValidationFlags::VALUE_MISSING) && self.Required() {
            let placeholder = self.get_placeholder_label_option();
            let is_value_missing = !self
                .list_of_options()
                .any(|e| e.Selected() && placeholder != Some(e));
            failed_flags.set(ValidationFlags::VALUE_MISSING, is_value_missing);
        }

        failed_flags
    }
}

enum Choice3<I, J, K> {
    First(I),
    Second(J),
    Third(K),
}

impl<I, J, K, T> Iterator for Choice3<I, J, K>
where
    I: Iterator<Item = T>,
    J: Iterator<Item = T>,
    K: Iterator<Item = T>,
{
    type Item = T;

    fn next(&mut self) -> Option<T> {
        match *self {
            Choice3::First(ref mut i) => i.next(),
            Choice3::Second(ref mut j) => j.next(),
            Choice3::Third(ref mut k) => k.next(),
        }
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        match *self {
            Choice3::First(ref i) => i.size_hint(),
            Choice3::Second(ref j) => j.size_hint(),
            Choice3::Third(ref k) => k.size_hint(),
        }
    }
}