/*
 * Copyright (c) 2024, Jelle Raaijmakers <jelle@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibMedia/PlaybackManager.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/Bindings/MediaSourcePrototype.h>
#include <LibWeb/DOM/Event.h>
#include <LibWeb/HTML/HTMLMediaElement.h>
#include <LibWeb/MediaSourceExtensions/EventNames.h>
#include <LibWeb/MediaSourceExtensions/MediaSource.h>
#include <LibWeb/MediaSourceExtensions/SourceBuffer.h>
#include <LibWeb/MediaSourceExtensions/SourceBufferList.h>
#include <LibWeb/MimeSniff/MimeType.h>

namespace Web::MediaSourceExtensions {

using Bindings::ReadyState;

GC_DEFINE_ALLOCATOR(MediaSource);

WebIDL::ExceptionOr<GC::Ref<MediaSource>> MediaSource::construct_impl(JS::Realm& realm)
{
    return realm.create<MediaSource>(realm);
}

MediaSource::MediaSource(JS::Realm& realm)
    : DOM::EventTarget(realm)
    , m_source_buffers(realm.create<SourceBufferList>(realm))
    , m_active_source_buffers(realm.create<SourceBufferList>(realm))
{
}

MediaSource::~MediaSource() = default;

void MediaSource::initialize(JS::Realm& realm)
{
    WEB_SET_PROTOTYPE_FOR_INTERFACE(MediaSource);
    Base::initialize(realm);
}

void MediaSource::visit_edges(Visitor& visitor)
{
    Base::visit_edges(visitor);
    visitor.visit(m_media_element_assigned_to);
    visitor.visit(m_source_buffers);
    visitor.visit(m_active_source_buffers);
}

void MediaSource::queue_a_media_source_task(GC::Ref<GC::Function<void()>> task)
{
    // FIXME: The MSE spec does not say what task source to use for its tasks. Should this use the media element's
    //        task source? We may not have access to it if we're in a worker.
    GC::Ptr<DOM::Document> document = nullptr;
    if (media_element_assigned_to() != nullptr)
        document = media_element_assigned_to()->document();

    HTML::queue_a_task(HTML::Task::Source::Unspecified, HTML::main_thread_event_loop(), document, task);
}

ReadyState MediaSource::ready_state() const
{
    return m_ready_state;
}

bool MediaSource::ready_state_is_closed() const
{
    return m_ready_state == ReadyState::Closed;
}

void MediaSource::set_has_ever_been_attached()
{
    m_has_ever_been_attached = true;
}

void MediaSource::set_ready_state_to_open_and_fire_sourceopen_event()
{
    m_ready_state = ReadyState::Open;

    // AD-HOC: Notify all demuxers that we have new data coming in and cannot consider the end of the buffer to be
    //         the end of the stream.
    for (size_t i = 0; i < m_source_buffers->length(); i++) {
        auto& source_buffer = *m_source_buffers->item(i);
        source_buffer.clear_reached_end_of_stream({});
    }

    queue_a_media_source_task(GC::create_function(heap(), [this] {
        auto event = DOM::Event::create(realm(), EventNames::sourceopen);
        dispatch_event(event);
    }));
}

void MediaSource::set_assigned_to_media_element(Badge<HTML::HTMLMediaElement>, HTML::HTMLMediaElement& media_element)
{
    m_media_element_assigned_to = media_element;
}

void MediaSource::unassign_from_media_element(Badge<HTML::HTMLMediaElement>)
{
    m_media_element_assigned_to = nullptr;
}

GC::Ref<SourceBufferList> MediaSource::source_buffers()
{
    return m_source_buffers;
}

GC::Ref<SourceBufferList> MediaSource::active_source_buffers()
{
    return m_active_source_buffers;
}

Utf16String MediaSource::next_track_id()
{
    return Utf16String::number(m_next_track_id++);
}

// https://w3c.github.io/media-source/#dom-mediasource-onsourceopen
void MediaSource::set_onsourceopen(GC::Ptr<WebIDL::CallbackType> event_handler)
{
    set_event_handler_attribute(EventNames::sourceopen, event_handler);
}

// https://w3c.github.io/media-source/#dom-mediasource-onsourceopen
GC::Ptr<WebIDL::CallbackType> MediaSource::onsourceopen()
{
    return event_handler_attribute(EventNames::sourceopen);
}

// https://w3c.github.io/media-source/#dom-mediasource-onsourceended
void MediaSource::set_onsourceended(GC::Ptr<WebIDL::CallbackType> event_handler)
{
    set_event_handler_attribute(EventNames::sourceended, event_handler);
}

// https://w3c.github.io/media-source/#dom-mediasource-onsourceended
GC::Ptr<WebIDL::CallbackType> MediaSource::onsourceended()
{
    return event_handler_attribute(EventNames::sourceended);
}

// https://w3c.github.io/media-source/#dom-mediasource-onsourceclose
void MediaSource::set_onsourceclose(GC::Ptr<WebIDL::CallbackType> event_handler)
{
    set_event_handler_attribute(EventNames::sourceclose, event_handler);
}

// https://w3c.github.io/media-source/#dom-mediasource-onsourceclose
GC::Ptr<WebIDL::CallbackType> MediaSource::onsourceclose()
{
    return event_handler_attribute(EventNames::sourceclose);
}

// https://w3c.github.io/media-source/#addsourcebuffer-method
WebIDL::ExceptionOr<GC::Ref<SourceBuffer>> MediaSource::add_source_buffer(String const& type)
{
    // 1. If type is an empty string then throw a TypeError exception and abort these steps.
    if (type.is_empty()) {
        return WebIDL::SimpleException {
            WebIDL::SimpleExceptionType::TypeError,
            "SourceBuffer type must not be empty"sv
        };
    }

    // 2. If type contains a MIME type that is not supported or contains a MIME type that is not
    //    supported with the types specified for the other SourceBuffer objects in sourceBuffers,
    //    then throw a NotSupportedError exception and abort these steps.
    if (!is_type_supported(type)) {
        return WebIDL::NotSupportedError::create(realm(), "Unsupported MIME type"_utf16);
    }

    // FIXME: 3. If the user agent can't handle any more SourceBuffer objects or if creating a SourceBuffer
    //           based on type would result in an unsupported SourceBuffer configuration, then throw a
    //           QuotaExceededError exception and abort these steps.

    // 4. If the readyState attribute is not in the "open" state then throw an InvalidStateError exception and abort these steps.
    if (ready_state() != ReadyState::Open)
        return WebIDL::InvalidStateError::create(realm(), "MediaSource is not open"_utf16);

    // 5. Let buffer be a new instance of a ManagedSourceBuffer if this is a ManagedMediaSource, or
    //    a SourceBuffer otherwise, with their respective associated resources.
    auto buffer = realm().create<SourceBuffer>(realm(), GC::Ref(*this));
    buffer->set_content_type(type);

    // FIXME: 6. Set buffer's [[generate timestamps flag]] to the value in the "Generate Timestamps Flag"
    //           column of the Media Source Extensions™ Byte Stream Format Registry entry that is
    //           associated with type.
    // FIXME: 7. If buffer's [[generate timestamps flag]] is true, set buffer's mode to "sequence".
    //           Otherwise, set buffer's mode to "segments".
    // 8. Append buffer to this's sourceBuffers.
    // 9. Queue a task to fire an event named addsourcebuffer at this's sourceBuffers.
    m_source_buffers->append(buffer);

    // 10. Return buffer.
    return buffer;
}

// https://w3c.github.io/media-source/#dom-mediasource-endofstream
WebIDL::ExceptionOr<void> MediaSource::end_of_stream(Optional<Bindings::EndOfStreamError> const& error)
{
    // 1. If the readyState attribute is not in the "open" state then throw an InvalidStateError exception
    //    and abort these steps.
    if (ready_state() != ReadyState::Open)
        return WebIDL::InvalidStateError::create(realm(), "MediaSource is not open"_utf16);

    // 2. If the updating attribute equals true on any SourceBuffer in sourceBuffers, then throw an
    //    InvalidStateError exception and abort these steps.
    for (size_t i = 0; i < m_source_buffers->length(); i++) {
        if (m_source_buffers->item(i)->updating())
            return WebIDL::InvalidStateError::create(realm(), "A SourceBuffer is still updating"_utf16);
    }

    // 3. Run the end of stream algorithm with the error parameter set to error.
    run_end_of_stream_algorithm(error);

    return {};
}

// https://w3c.github.io/media-source/#end-of-stream-algorithm
void MediaSource::run_end_of_stream_algorithm(Optional<Bindings::EndOfStreamError> const& error)
{
    // 1. Change the readyState attribute value to "ended".
    m_ready_state = ReadyState::Ended;

    // 2. Queue a task to fire an event named sourceended at the MediaSource.
    queue_a_media_source_task(GC::create_function(heap(), [this] {
        dispatch_event(DOM::Event::create(realm(), EventNames::sourceended));
    }));

    // AD-HOC: Notify all demuxers that end of stream was reached, so that they can return the requisite error and
    //         allow decoders to flush all their frames.
    for (size_t i = 0; i < m_source_buffers->length(); i++) {
        auto& source_buffer = *m_source_buffers->item(i);
        source_buffer.set_reached_end_of_stream({});
    }

    // 3. If error is not set:
    if (!error.has_value()) {
        // 1. Run the duration change algorithm with new duration set to the largest track buffer ranges
        //    end time across all the track buffers across all SourceBuffer objects in sourceBuffers.
        // FIXME: Implement duration change based on track buffer ranges.

        // 2. Notify the media element that it now has all of the media data.
        // FIXME: Signal to the HTMLMediaElement that all data has been provided.
        return;
    }

    // 4. If error is set to "network":
    if (error.value() == Bindings::EndOfStreamError::Network) {
        // FIXME: If the HTMLMediaElement's readyState attribute equals HAVE_NOTHING:
        //            Run the "If the media data cannot be fetched at all" steps of the resource fetch algorithm.
        //        Otherwise:
        //            Run the "If the connection is interrupted after some media data has been received" steps
        //            of the resource fetch algorithm.
        return;
    }

    // 5. If error is set to "decode":
    if (error.value() == Bindings::EndOfStreamError::Decode) {
        // FIXME: If the HTMLMediaElement's readyState attribute equals HAVE_NOTHING:
        //            Run the "If the media data can be fetched but is found by inspection to be in an
        //            unsupported format" steps of the resource fetch algorithm.
        //        Otherwise:
        //            Run the "If the media data can be fetched but has fatal network errors" steps of the
        //            resource fetch algorithm.
        return;
    }
}

// https://w3c.github.io/media-source/#dom-mediasource-duration
double MediaSource::duration() const
{
    // 1. If the readyState attribute is "closed" then return NaN and abort these steps.
    if (ready_state() == ReadyState::Closed)
        return NAN;

    // 2. Return the current value of the attribute.
    return m_duration;
}

// https://w3c.github.io/media-source/#dom-mediasource-duration
WebIDL::ExceptionOr<void> MediaSource::set_duration(double new_duration)
{
    // 1. If the value being set is negative or NaN then throw a TypeError exception and abort these steps.
    if (new_duration < 0 || isnan(new_duration))
        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, "duration must not be negative or NaN"sv };

    // 2. If the readyState attribute is not in the "open" state then throw an InvalidStateError exception
    //    and abort these steps.
    if (ready_state() != ReadyState::Open)
        return WebIDL::InvalidStateError::create(realm(), "MediaSource is not open"_utf16);

    // 3. If the updating attribute equals true on any SourceBuffer in sourceBuffers, then throw an
    //    InvalidStateError exception and abort these steps.
    for (size_t i = 0; i < m_source_buffers->length(); i++) {
        if (m_source_buffers->item(i)->updating())
            return WebIDL::InvalidStateError::create(realm(), "A SourceBuffer is still updating"_utf16);
    }

    // 4. Run the duration change algorithm with new duration set to the value being assigned to this attribute.
    run_duration_change_algorithm(new_duration);

    return {};
}

// https://w3c.github.io/media-source/#duration-change-algorithm
void MediaSource::run_duration_change_algorithm(double new_duration)
{
    // 1. If the current value of duration is equal to new duration, then return.
    if (m_duration == new_duration)
        return;

    // 2. If new duration is less than the highest presentation timestamp of any buffered coded frames
    //    for all SourceBuffer objects in sourceBuffers, then throw an InvalidStateError exception and
    //    abort these steps.
    // FIXME: Check highest presentation timestamp across all track buffers.

    // 3. Let highest end time be the largest track buffer ranges end time across all the track buffers
    //    across all SourceBuffer objects in sourceBuffers.
    // 4. If new duration is less than highest end time, then update new duration to equal highest end time.
    // FIXME: Clamp new_duration to highest end time.

    // 5. Update duration to new duration.
    m_duration = new_duration;

    // 6. Use the mirror if necessary algorithm to run the following steps in Window to update the
    //    media element's duration:
    // FIXME: Mirror to the Window when workers are supported.
    //        Update the media element's duration to new duration.
    //        Run the HTMLMediaElement duration change algorithm.
    media_element_assigned_to()->set_duration({}, new_duration);
    media_element_assigned_to()->playback_manager().set_duration(AK::Duration::from_seconds_f64(new_duration));
}

// https://w3c.github.io/media-source/#dom-mediasource-istypesupported
bool MediaSource::is_type_supported(String const& type)
{
    // 1. If type is an empty string, then return false.
    if (type.is_empty())
        return false;

    // 2. If type does not contain a valid MIME type string, then return false.
    auto mime_type = MimeSniff::MimeType::parse(type);
    if (!mime_type.has_value())
        return false;

    // FIXME: Ask LibMedia about what it supports instead of hardcoding this.

    // 3. If type contains a media type or media subtype that the MediaSource does not support, then
    //    return false.
    auto type_and_subtype_are_supported = [&] {
        if (mime_type->type() == "video" && mime_type->subtype() == "webm")
            return true;
        if (mime_type->type() == "audio" && mime_type->subtype() == "webm")
            return true;
        return false;
    }();
    if (!type_and_subtype_are_supported)
        return false;

    // 4. If type contains a codec that the MediaSource does not support, then return false.
    // 5. If the MediaSource does not support the specified combination of media type, media
    //    subtype, and codecs then return false.
    auto codecs_iter = mime_type->parameters().find("codecs"sv);
    if (codecs_iter == mime_type->parameters().end())
        return false;
    auto codecs = codecs_iter->value.bytes_as_string_view();
    auto had_unsupported_codec = false;
    codecs.for_each_split_view(',', SplitBehavior::Nothing, [&](auto const& codec) {
        if (!codec.starts_with("vp9"sv) && !codec.starts_with("vp09"sv) && !codec.starts_with("opus"sv)) {
            had_unsupported_codec = true;
            return IterationDecision::Break;
        }
        return IterationDecision::Continue;
    });
    if (had_unsupported_codec)
        return false;

    // 6. Return true.
    return true;
}

}