/*
 * Copyright (c) 2021, Liav A. <liavalb@hotmail.co.il>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Checked.h>
#include <AK/Try.h>
#include <Kernel/API/POSIX/errno.h>
#include <Kernel/Debug.h>
#include <Kernel/Devices/DeviceManagement.h>
#include <Kernel/Graphics/FramebufferDevice.h>
#include <Kernel/Graphics/GraphicsManagement.h>
#include <Kernel/Memory/AnonymousVMObject.h>
#include <Kernel/Memory/MemoryManager.h>
#include <Kernel/Process.h>
#include <Kernel/Sections.h>
#include <Kernel/StdLib.h>

#define MAX_RESOLUTION_WIDTH 4096
#define MAX_RESOLUTION_HEIGHT 2160

namespace Kernel {

ErrorOr<void> GenericFramebufferDevice::verify_head_index(int head_index) const
{
    if (head_index < 0)
        return Error::from_errno(EINVAL);
    if (!multihead_support() && head_index > 0)
        return Error::from_errno(ENOTSUP);
    return {};
}

ErrorOr<void> GenericFramebufferDevice::ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg)
{
    if (request != FB_IOCTL_GET_HEAD_EDID) {
        // Allow anyone to query the EDID. Eventually we'll publish the current EDID on /sys
        // so it doesn't really make sense to require the video pledge to query it.
        TRY(Process::current().require_promise(Pledge::video));
    }
    switch (request) {
    case FB_IOCTL_GET_PROPERTIES: {
        auto user_properties = static_ptr_cast<FBProperties*>(arg);
        FBProperties properties {};
        auto adapter = m_graphics_adapter.strong_ref();
        if (!adapter)
            return Error::from_errno(EIO);
        properties.multihead_support = multihead_support();
        properties.flushing_support = flushing_support();
        properties.doublebuffer_support = adapter->double_framebuffering_capable();
        properties.partial_flushing_support = partial_flushing_support();
        return copy_to_user(user_properties, &properties);
    }
    case FB_IOCTL_GET_HEAD_PROPERTIES: {
        auto user_head_properties = static_ptr_cast<FBHeadProperties*>(arg);
        FBHeadProperties head_properties {};
        TRY(copy_from_user(&head_properties, user_head_properties));
        TRY(verify_head_index(head_properties.head_index));

        head_properties.pitch = TRY(pitch(head_properties.head_index));
        head_properties.width = TRY(width(head_properties.head_index));
        head_properties.height = TRY(height(head_properties.head_index));
        head_properties.buffer_length = TRY(buffer_length(head_properties.head_index));
        head_properties.offset = TRY(vertical_offset(head_properties.head_index));
        return copy_to_user(user_head_properties, &head_properties);
    }
    case FB_IOCTL_GET_HEAD_EDID: {
        auto user_head_edid = static_ptr_cast<FBHeadEDID*>(arg);
        FBHeadEDID head_edid {};
        TRY(copy_from_user(&head_edid, user_head_edid));
        TRY(verify_head_index(head_edid.head_index));

        auto edid_bytes = TRY(get_edid(head_edid.head_index));
        if (head_edid.bytes != nullptr) {
            // Only return the EDID if a buffer was provided. Either way,
            // we'll write back the bytes_size with the actual size
            if (head_edid.bytes_size < edid_bytes.size()) {
                head_edid.bytes_size = edid_bytes.size();
                TRY(copy_to_user(user_head_edid, &head_edid));
                return Error::from_errno(EOVERFLOW);
            }
            TRY(copy_to_user(head_edid.bytes, (void const*)edid_bytes.data(), edid_bytes.size()));
        }
        head_edid.bytes_size = edid_bytes.size();
        return copy_to_user(user_head_edid, &head_edid);
    }
    case FB_IOCTL_SET_HEAD_RESOLUTION: {
        auto user_head_resolution = static_ptr_cast<FBHeadResolution const*>(arg);
        auto head_resolution = TRY(copy_typed_from_user(user_head_resolution));
        TRY(verify_head_index(head_resolution.head_index));

        if (head_resolution.pitch < 0)
            return Error::from_errno(EINVAL);
        if (head_resolution.width < 0)
            return Error::from_errno(EINVAL);
        if (head_resolution.height < 0)
            return Error::from_errno(EINVAL);
        TRY(set_head_resolution(head_resolution.head_index, head_resolution.width, head_resolution.height, head_resolution.pitch));
        return {};
    }
    case FB_IOCTL_SET_HEAD_VERTICAL_OFFSET_BUFFER: {
        auto user_head_vertical_buffer_offset = static_ptr_cast<FBHeadVerticalOffset const*>(arg);
        auto head_vertical_buffer_offset = TRY(copy_typed_from_user(user_head_vertical_buffer_offset));
        TRY(verify_head_index(head_vertical_buffer_offset.head_index));

        if (head_vertical_buffer_offset.offsetted < 0 || head_vertical_buffer_offset.offsetted > 1)
            return Error::from_errno(EINVAL);
        TRY(set_head_buffer(head_vertical_buffer_offset.head_index, head_vertical_buffer_offset.offsetted));
        return {};
    }
    case FB_IOCTL_GET_HEAD_VERTICAL_OFFSET_BUFFER: {
        auto user_head_vertical_buffer_offset = static_ptr_cast<FBHeadVerticalOffset*>(arg);
        FBHeadVerticalOffset head_vertical_buffer_offset {};
        TRY(copy_from_user(&head_vertical_buffer_offset, user_head_vertical_buffer_offset));
        TRY(verify_head_index(head_vertical_buffer_offset.head_index));

        head_vertical_buffer_offset.offsetted = TRY(vertical_offsetted(head_vertical_buffer_offset.head_index));
        return copy_to_user(user_head_vertical_buffer_offset, &head_vertical_buffer_offset);
    }
    case FB_IOCTL_FLUSH_HEAD_BUFFERS: {
        if (!partial_flushing_support())
            return Error::from_errno(ENOTSUP);
        auto user_flush_rects = static_ptr_cast<FBFlushRects const*>(arg);
        auto flush_rects = TRY(copy_typed_from_user(user_flush_rects));
        if (Checked<unsigned>::multiplication_would_overflow(flush_rects.count, sizeof(FBRect)))
            return Error::from_errno(EFAULT);
        SpinlockLocker locker(m_flushing_lock);
        if (flush_rects.count > 0) {
            for (unsigned i = 0; i < flush_rects.count; i++) {
                FBRect user_dirty_rect;
                TRY(copy_from_user(&user_dirty_rect, &flush_rects.rects[i]));
                TRY(flush_rectangle(flush_rects.buffer_index, user_dirty_rect));
            }
        }
        return {};
    };
    case FB_IOCTL_FLUSH_HEAD: {
        if (!flushing_support())
            return Error::from_errno(ENOTSUP);
        // Note: We accept a FBRect, but we only really care about the head_index value.
        auto user_rect = static_ptr_cast<FBRect const*>(arg);
        auto rect = TRY(copy_typed_from_user(user_rect));
        TRY(verify_head_index(rect.head_index));
        TRY(flush_head_buffer(rect.head_index));
        return {};
    }
    default:
        return EINVAL;
    };
}

GenericFramebufferDevice::GenericFramebufferDevice(const GenericGraphicsAdapter& adapter)
    : BlockDevice(29, GraphicsManagement::the().allocate_minor_device_number())
    , m_graphics_adapter(adapter)
{
}

}