/*
 * This file is part of mpv.
 *
 * mpv is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * mpv is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <sys/mman.h>
#include <poll.h>
#include <unistd.h>

#include <drm_fourcc.h>
#include <libswscale/swscale.h>

#include "drm_common.h"

#include "common/msg.h"
#include "osdep/timer.h"
#include "sub/osd.h"
#include "video/fmt-conversion.h"
#include "video/mp_image.h"
#include "video/sws_utils.h"
#include "vo.h"

#define IMGFMT_XRGB8888 IMGFMT_BGR0
#if BYTE_ORDER == BIG_ENDIAN
#define IMGFMT_XRGB2101010 pixfmt2imgfmt(AV_PIX_FMT_GBRP10BE)
#else
#define IMGFMT_XRGB2101010 pixfmt2imgfmt(AV_PIX_FMT_GBRP10LE)
#endif

#define BYTES_PER_PIXEL 4
#define BITS_PER_PIXEL 32
#define USE_MASTER 0

struct framebuffer {
    uint32_t width;
    uint32_t height;
    uint32_t stride;
    uint32_t size;
    uint32_t handle;
    uint8_t *map;
    uint32_t fb;
};

struct kms_frame {
    struct framebuffer *fb;
    struct drm_vsync_tuple vsync;
};

struct priv {
    char *connector_spec;
    int mode_id;

    struct kms *kms;
    drmModeCrtc *old_crtc;
    drmEventContext ev;

    bool vt_switcher_active;
    struct vt_switcher vt_switcher;

    int swapchain_depth;
    unsigned int buf_count;
    struct framebuffer *bufs;
    int front_buf;
    bool active;
    bool waiting_for_flip;
    bool still;
    bool paused;

    struct kms_frame **fb_queue;
    unsigned int fb_queue_len;
    struct framebuffer *cur_fb;

    uint32_t drm_format;
    enum mp_imgfmt imgfmt;

    int32_t screen_w;
    int32_t screen_h;
    struct mp_image *last_input;
    struct mp_image *cur_frame;
    struct mp_image *cur_frame_cropped;
    struct mp_rect src;
    struct mp_rect dst;
    struct mp_osd_res osd;
    struct mp_sws_context *sws;

    struct drm_vsync_tuple vsync;
    struct vo_vsync_info vsync_info;
};

static void fb_destroy(int fd, struct framebuffer *buf)
{
    if (buf->map) {
        munmap(buf->map, buf->size);
    }
    if (buf->fb) {
        drmModeRmFB(fd, buf->fb);
    }
    if (buf->handle) {
        struct drm_mode_destroy_dumb dreq = {
            .handle = buf->handle,
        };
        drmIoctl(fd, DRM_IOCTL_MODE_DESTROY_DUMB, &dreq);
    }
}

static bool fb_setup_single(struct vo *vo, int fd, struct framebuffer *buf)
{
    struct priv *p = vo->priv;

    buf->handle = 0;

    // create dumb buffer
    struct drm_mode_create_dumb creq = {
        .width = buf->width,
        .height = buf->height,
        .bpp = BITS_PER_PIXEL,
    };
    if (drmIoctl(fd, DRM_IOCTL_MODE_CREATE_DUMB, &creq) < 0) {
        MP_ERR(vo, "Cannot create dumb buffer: %s\n", mp_strerror(errno));
        goto err;
    }
    buf->stride = creq.pitch;
    buf->size = creq.size;
    buf->handle = creq.handle;

    // create framebuffer object for the dumb-buffer
    int ret = drmModeAddFB2(fd, buf->width, buf->height,
                            p->drm_format,
                            (uint32_t[4]){buf->handle, 0, 0, 0},
                            (uint32_t[4]){buf->stride, 0, 0, 0},
                            (uint32_t[4]){0, 0, 0, 0},
                            &buf->fb, 0);
    if (ret) {
        MP_ERR(vo, "Cannot create framebuffer: %s\n", mp_strerror(errno));
        goto err;
    }

    // prepare buffer for memory mapping
    struct drm_mode_map_dumb mreq = {
        .handle = buf->handle,
    };
    if (drmIoctl(fd, DRM_IOCTL_MODE_MAP_DUMB, &mreq)) {
        MP_ERR(vo, "Cannot map dumb buffer: %s\n", mp_strerror(errno));
        goto err;
    }

    // perform actual memory mapping
    buf->map = mmap(0, buf->size, PROT_READ | PROT_WRITE, MAP_SHARED,
                    fd, mreq.offset);
    if (buf->map == MAP_FAILED) {
        MP_ERR(vo, "Cannot map dumb buffer: %s\n", mp_strerror(errno));
        goto err;
    }

    memset(buf->map, 0, buf->size);
    return true;

err:
    fb_destroy(fd, buf);
    return false;
}

static bool fb_setup_buffers(struct vo *vo)
{
    struct priv *p = vo->priv;

    p->bufs = talloc_zero_array(p, struct framebuffer, p->buf_count);

    p->front_buf = 0;
    for (unsigned int i = 0; i < p->buf_count; i++) {
        p->bufs[i].width = p->kms->mode.mode.hdisplay;
        p->bufs[i].height = p->kms->mode.mode.vdisplay;
    }

    for (unsigned int i = 0; i < p->buf_count; i++) {
        if (!fb_setup_single(vo, p->kms->fd, &p->bufs[i])) {
            MP_ERR(vo, "Cannot create framebuffer\n");
            for (unsigned int j = 0; j < i; j++) {
                fb_destroy(p->kms->fd, &p->bufs[j]);
            }
            return false;
        }
    }

    p->cur_fb = &p->bufs[0];

    return true;
}

static void get_vsync(struct vo *vo, struct vo_vsync_info *info)
{
    struct priv *p = vo->priv;
    *info = p->vsync_info;
}

static bool crtc_setup(struct vo *vo)
{
    struct priv *p = vo->priv;
    if (p->active)
        return true;
    p->old_crtc = drmModeGetCrtc(p->kms->fd, p->kms->crtc_id);
    int ret = drmModeSetCrtc(p->kms->fd, p->kms->crtc_id,
                             p->cur_fb->fb,
                             0, 0, &p->kms->connector->connector_id, 1,
                             &p->kms->mode.mode);
    p->active = true;
    return ret == 0;
}

static void crtc_release(struct vo *vo)
{
    struct priv *p = vo->priv;

    if (!p->active)
        return;
    p->active = false;

    // wait for current page flip
    while (p->waiting_for_flip) {
        int ret = drmHandleEvent(p->kms->fd, &p->ev);
        if (ret) {
            MP_ERR(vo, "drmHandleEvent failed: %i\n", ret);
            break;
        }
    }

    if (p->old_crtc) {
        drmModeSetCrtc(p->kms->fd, p->old_crtc->crtc_id,
                       p->old_crtc->buffer_id,
                       p->old_crtc->x, p->old_crtc->y,
                       &p->kms->connector->connector_id, 1,
                       &p->old_crtc->mode);
        drmModeFreeCrtc(p->old_crtc);
        p->old_crtc = NULL;
    }
}

static void release_vt(void *data)
{
    struct vo *vo = data;
    crtc_release(vo);
    if (USE_MASTER) {
        //this function enables support for switching to x, weston etc.
        //however, for whatever reason, it can be called only by root users.
        //until things change, this is commented.
        struct priv *p = vo->priv;
        if (drmDropMaster(p->kms->fd)) {
            MP_WARN(vo, "Failed to drop DRM master: %s\n", mp_strerror(errno));
        }
    }
}

static void acquire_vt(void *data)
{
    struct vo *vo = data;
    if (USE_MASTER) {
        struct priv *p = vo->priv;
        if (drmSetMaster(p->kms->fd)) {
            MP_WARN(vo, "Failed to acquire DRM master: %s\n", mp_strerror(errno));
        }
    }

    crtc_setup(vo);
}

static void wait_events(struct vo *vo, int64_t until_time_us)
{
    struct priv *p = vo->priv;
    if (p->vt_switcher_active) {
        int64_t wait_us = until_time_us - mp_time_us();
        int timeout_ms = MPCLAMP((wait_us + 500) / 1000, 0, 10000);
        vt_switcher_poll(&p->vt_switcher, timeout_ms);
    } else {
        vo_wait_default(vo, until_time_us);
    }
}

static void wakeup(struct vo *vo)
{
    struct priv *p = vo->priv;
    if (p->vt_switcher_active)
        vt_switcher_interrupt_poll(&p->vt_switcher);
}

static int reconfig(struct vo *vo, struct mp_image_params *params)
{
    struct priv *p = vo->priv;

    vo->dwidth = p->screen_w;
    vo->dheight = p->screen_h;
    vo_get_src_dst_rects(vo, &p->src, &p->dst, &p->osd);

    int w = p->dst.x1 - p->dst.x0;
    int h = p->dst.y1 - p->dst.y0;

    p->sws->src = *params;
    p->sws->dst = (struct mp_image_params) {
        .imgfmt = p->imgfmt,
        .w = w,
        .h = h,
        .p_w = 1,
        .p_h = 1,
    };

    talloc_free(p->cur_frame);
    p->cur_frame = mp_image_alloc(p->imgfmt, p->screen_w, p->screen_h);
    mp_image_params_guess_csp(&p->sws->dst);
    mp_image_set_params(p->cur_frame, &p->sws->dst);
    mp_image_set_size(p->cur_frame, p->screen_w, p->screen_h);

    talloc_free(p->cur_frame_cropped);
    p->cur_frame_cropped = mp_image_new_dummy_ref(p->cur_frame);
    mp_image_crop_rc(p->cur_frame_cropped, p->dst);

    talloc_free(p->last_input);
    p->last_input = NULL;

    if (mp_sws_reinit(p->sws) < 0)
        return -1;

    p->vsync_info.vsync_duration = 0;
    p->vsync_info.skipped_vsyncs = -1;
    p->vsync_info.last_queue_display_time = -1;

    vo->want_redraw = true;
    return 0;
}

static void wait_on_flip(struct vo *vo)
{
    struct priv *p = vo->priv;

    // poll page flip finish event
    while (p->waiting_for_flip) {
        const int timeout_ms = 3000;
        struct pollfd fds[1] = { { .events = POLLIN, .fd = p->kms->fd } };
        poll(fds, 1, timeout_ms);
        if (fds[0].revents & POLLIN) {
            const int ret = drmHandleEvent(p->kms->fd, &p->ev);
            if (ret != 0) {
                MP_ERR(vo, "drmHandleEvent failed: %i\n", ret);
                return;
            }
        }
    }
}

static struct framebuffer *get_new_fb(struct vo *vo)
{
    struct priv *p = vo->priv;

    p->front_buf++;
    p->front_buf %= p->buf_count;

    return &p->bufs[p->front_buf];
}

static void draw_image(struct vo *vo, mp_image_t *mpi, struct framebuffer *front_buf)
{
    struct priv *p = vo->priv;

    if (p->active && front_buf != NULL) {
        if (mpi) {
            struct mp_image src = *mpi;
            struct mp_rect src_rc = p->src;
            src_rc.x0 = MP_ALIGN_DOWN(src_rc.x0, mpi->fmt.align_x);
            src_rc.y0 = MP_ALIGN_DOWN(src_rc.y0, mpi->fmt.align_y);
            mp_image_crop_rc(&src, src_rc);

            mp_image_clear(p->cur_frame, 0, 0, p->cur_frame->w, p->dst.y0);
            mp_image_clear(p->cur_frame, 0, p->dst.y1, p->cur_frame->w, p->cur_frame->h);
            mp_image_clear(p->cur_frame, 0, p->dst.y0, p->dst.x0, p->dst.y1);
            mp_image_clear(p->cur_frame, p->dst.x1, p->dst.y0, p->cur_frame->w, p->dst.y1);

            mp_sws_scale(p->sws, p->cur_frame_cropped, &src);
            osd_draw_on_image(vo->osd, p->osd, src.pts, 0, p->cur_frame);
        } else {
            mp_image_clear(p->cur_frame, 0, 0, p->cur_frame->w, p->cur_frame->h);
            osd_draw_on_image(vo->osd, p->osd, 0, 0, p->cur_frame);
        }

        if (p->drm_format == DRM_FORMAT_XRGB2101010) {
            // Pack GBRP10 image into XRGB2101010 for DRM
            const int w = p->cur_frame->w;
            const int h = p->cur_frame->h;

            const int g_padding = p->cur_frame->stride[0]/sizeof(uint16_t) - w;
            const int b_padding = p->cur_frame->stride[1]/sizeof(uint16_t) - w;
            const int r_padding = p->cur_frame->stride[2]/sizeof(uint16_t) - w;
            const int fbuf_padding = front_buf->stride/sizeof(uint32_t) - w;

            uint16_t *g_ptr = (uint16_t*)p->cur_frame->planes[0];
            uint16_t *b_ptr = (uint16_t*)p->cur_frame->planes[1];
            uint16_t *r_ptr = (uint16_t*)p->cur_frame->planes[2];
            uint32_t *fbuf_ptr = (uint32_t*)front_buf->map;
            for (unsigned y = 0; y < h; ++y) {
                for (unsigned x = 0; x < w; ++x) {
                    *fbuf_ptr++ = (*r_ptr++ << 20) | (*g_ptr++ << 10) | (*b_ptr++);
                }
                g_ptr += g_padding;
                b_ptr += b_padding;
                r_ptr += r_padding;
                fbuf_ptr += fbuf_padding;
            }
        } else { // p->drm_format == DRM_FORMAT_XRGB8888
            memcpy_pic(front_buf->map, p->cur_frame->planes[0],
                       p->cur_frame->w * BYTES_PER_PIXEL, p->cur_frame->h,
                       front_buf->stride,
                       p->cur_frame->stride[0]);
        }
    }

    if (mpi != p->last_input) {
        talloc_free(p->last_input);
        p->last_input = mpi;
    }
}

static void enqueue_frame(struct vo *vo, struct framebuffer *fb)
{
    struct priv *p = vo->priv;

    p->vsync.sbc++;
    struct kms_frame *new_frame = talloc(p, struct kms_frame);
    new_frame->fb = fb;
    new_frame->vsync = p->vsync;
    MP_TARRAY_APPEND(p, p->fb_queue, p->fb_queue_len, new_frame);
}

static void dequeue_frame(struct vo *vo)
{
    struct priv *p = vo->priv;

    talloc_free(p->fb_queue[0]);
    MP_TARRAY_REMOVE_AT(p->fb_queue, p->fb_queue_len, 0);
}

static void swapchain_step(struct vo *vo)
{
    struct priv *p = vo->priv;

    if (p->fb_queue_len > 0) {
        dequeue_frame(vo);
    }
}

static void draw_frame(struct vo *vo, struct vo_frame *frame)
{
    struct priv *p = vo->priv;

    if (!p->active)
        return;

    p->still = frame->still;

    // we redraw the entire image when OSD needs to be redrawn
    const bool repeat = frame->repeat && !frame->redraw;

    struct framebuffer *fb =  &p->bufs[p->front_buf];
    if (!repeat) {
        fb = get_new_fb(vo);
        draw_image(vo, mp_image_new_ref(frame->current), fb);
    }

    enqueue_frame(vo, fb);
}

static void queue_flip(struct vo *vo, struct kms_frame *frame)
{
    int ret = 0;
    struct priv *p = vo->priv;

    p->cur_fb = frame->fb;

    // Alloc and fill the data struct for the page flip callback
    struct drm_pflip_cb_closure *data = talloc(p, struct drm_pflip_cb_closure);
    data->frame_vsync = &frame->vsync;
    data->vsync = &p->vsync;
    data->vsync_info = &p->vsync_info;
    data->waiting_for_flip = &p->waiting_for_flip;
    data->log = vo->log;

    ret = drmModePageFlip(p->kms->fd, p->kms->crtc_id,
                          p->cur_fb->fb,
                          DRM_MODE_PAGE_FLIP_EVENT, data);
    if (ret) {
        MP_WARN(vo, "Failed to queue page flip: %s\n", mp_strerror(errno));
    } else {
        p->waiting_for_flip = true;
    }
}

static void flip_page(struct vo *vo)
{
    struct priv *p = vo->priv;
    const bool drain = p->paused || p->still;

    if (!p->active)
        return;

    while (drain || p->fb_queue_len > p->swapchain_depth) {
        if (p->waiting_for_flip) {
            wait_on_flip(vo);
            swapchain_step(vo);
        }
        if (p->fb_queue_len <= 1)
            break;
        if (!p->fb_queue[1] || !p->fb_queue[1]->fb) {
            MP_ERR(vo, "Hole in swapchain?\n");
            swapchain_step(vo);
            continue;
        }
        queue_flip(vo, p->fb_queue[1]);
    }
}

static void uninit(struct vo *vo)
{
    struct priv *p = vo->priv;

    crtc_release(vo);

    while (p->fb_queue_len > 0) {
        swapchain_step(vo);
    }

    if (p->kms) {
        for (unsigned int i = 0; i < p->buf_count; i++)
            fb_destroy(p->kms->fd, &p->bufs[i]);
        kms_destroy(p->kms);
        p->kms = NULL;
    }

    if (p->vt_switcher_active)
        vt_switcher_destroy(&p->vt_switcher);

    talloc_free(p->last_input);
    talloc_free(p->cur_frame);
    talloc_free(p->cur_frame_cropped);
}

static int preinit(struct vo *vo)
{
    struct priv *p = vo->priv;
    p->sws = mp_sws_alloc(vo);
    p->sws->log = vo->log;
    mp_sws_enable_cmdline_opts(p->sws, vo->global);
    p->ev.version = DRM_EVENT_CONTEXT_VERSION;
    p->ev.page_flip_handler = &drm_pflip_cb;

    p->vt_switcher_active = vt_switcher_init(&p->vt_switcher, vo->log);
    if (p->vt_switcher_active) {
        vt_switcher_acquire(&p->vt_switcher, acquire_vt, vo);
        vt_switcher_release(&p->vt_switcher, release_vt, vo);
    } else {
        MP_WARN(vo, "Failed to set up VT switcher. Terminal switching will be unavailable.\n");
    }

    p->kms = kms_create(vo->log,
                        vo->opts->drm_opts->drm_connector_spec,
                        vo->opts->drm_opts->drm_mode_spec,
                        0, 0, false);
    if (!p->kms) {
        MP_ERR(vo, "Failed to create KMS.\n");
        goto err;
    }

    if (vo->opts->drm_opts->drm_format == DRM_OPTS_FORMAT_XRGB2101010) {
        p->drm_format = DRM_FORMAT_XRGB2101010;
        p->imgfmt = IMGFMT_XRGB2101010;
    } else {
        p->drm_format = DRM_FORMAT_XRGB8888;;
        p->imgfmt = IMGFMT_XRGB8888;
    }

    p->swapchain_depth = vo->opts->swapchain_depth;
    p->buf_count = p->swapchain_depth + 1;
    if (!fb_setup_buffers(vo)) {
        MP_ERR(vo, "Failed to set up buffers.\n");
        goto err;
    }

    uint64_t has_dumb = 0;
    if (drmGetCap(p->kms->fd, DRM_CAP_DUMB_BUFFER, &has_dumb) < 0
        || has_dumb == 0) {
        MP_ERR(vo, "Card \"%d\" does not support dumb buffers.\n",
               p->kms->card_no);
        goto err;
    }

    p->screen_w = p->bufs[0].width;
    p->screen_h = p->bufs[0].height;

    if (!crtc_setup(vo)) {
        MP_ERR(vo, "Cannot set CRTC: %s\n", mp_strerror(errno));
        goto err;
    }

    if (vo->opts->force_monitor_aspect != 0.0) {
        vo->monitor_par = p->screen_w / (double) p->screen_h /
                          vo->opts->force_monitor_aspect;
    } else {
        vo->monitor_par = 1 / vo->opts->monitor_pixel_aspect;
    }
    mp_verbose(vo->log, "Monitor pixel aspect: %g\n", vo->monitor_par);

    p->vsync_info.vsync_duration = 0;
    p->vsync_info.skipped_vsyncs = -1;
    p->vsync_info.last_queue_display_time = -1;

    return 0;

err:
    uninit(vo);
    return -1;
}

static int query_format(struct vo *vo, int format)
{
    return sws_isSupportedInput(imgfmt2pixfmt(format));
}

static int control(struct vo *vo, uint32_t request, void *arg)
{
    struct priv *p = vo->priv;
    switch (request) {
    case VOCTRL_SCREENSHOT_WIN:
        *(struct mp_image**)arg = mp_image_new_copy(p->cur_frame);
        return VO_TRUE;
    case VOCTRL_SET_PANSCAN:
        if (vo->config_ok)
            reconfig(vo, vo->params);
        return VO_TRUE;
    case VOCTRL_GET_DISPLAY_FPS: {
        double fps = kms_get_display_fps(p->kms);
        if (fps <= 0)
            break;
        *(double*)arg = fps;
        return VO_TRUE;
    }
    case VOCTRL_PAUSE:
        vo->want_redraw = true;
        p->paused = true;
        return VO_TRUE;
    case VOCTRL_RESUME:
        p->paused = false;
        p->vsync_info.last_queue_display_time = -1;
        p->vsync_info.skipped_vsyncs = 0;
        p->vsync.ust = 0;
        p->vsync.msc = 0;
        return VO_TRUE;
    }
    return VO_NOTIMPL;
}

#define OPT_BASE_STRUCT struct priv

const struct vo_driver video_out_drm = {
    .name = "drm",
    .description = "Direct Rendering Manager (software scaling)",
    .preinit = preinit,
    .query_format = query_format,
    .reconfig = reconfig,
    .control = control,
    .draw_frame = draw_frame,
    .flip_page = flip_page,
    .get_vsync = get_vsync,
    .uninit = uninit,
    .wait_events = wait_events,
    .wakeup = wakeup,
    .priv_size = sizeof(struct priv),
};