/* SPDX-License-Identifier: Apache-2.0 */
/*
 * A Schcom client, and the test for the compositor.
 *
 * Draws a flat rectangle of a known colour at a known position and commits it.
 * Both of those are chosen so the result can be checked from outside the
 * machine: `make schcom-shot` screendumps the framebuffer and a script on the
 * host asserts the pixel at a given coordinate. That is the same oracle
 * pattern the SchFS round-trip uses -- something with no connection to the code
 * under test has to agree that it worked.
 *
 *   schcom-demo [--colour 0xRRGGBB] [--at X Y] [--size W H] [--wait SECONDS]
 */

#define _GNU_SOURCE
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/shm.h>
#include <sys/socket.h>
#include <sys/un.h>

#include "proto.h"

static int
read_all(int fd, void *buf, size_t n)
{
    unsigned char *p = buf;
    while (n) {
        ssize_t r = read(fd, p, n);
        if (r == 0) return -1;
        if (r < 0) { if (errno == EINTR) continue; return -1; }
        p += r; n -= (size_t)r;
    }
    return 0;
}

int
main(int argc, char **argv)
{
    uint32_t colour = 0x00C04020;
    int32_t  at_x = 100, at_y = 80;
    uint32_t w = 240, h = 160;
    int      wait_s = 3;

    for (int i = 1; i < argc; i++) {
        if (!strcmp(argv[i], "--colour") && i + 1 < argc)
            colour = (uint32_t)strtoul(argv[++i], NULL, 0);
        else if (!strcmp(argv[i], "--at") && i + 2 < argc) {
            at_x = atoi(argv[++i]); at_y = atoi(argv[++i]);
        } else if (!strcmp(argv[i], "--size") && i + 2 < argc) {
            w = (uint32_t)atoi(argv[++i]); h = (uint32_t)atoi(argv[++i]);
        } else if (!strcmp(argv[i], "--wait") && i + 1 < argc)
            wait_s = atoi(argv[++i]);
    }

    int fd = socket(AF_UNIX, SOCK_STREAM, 0);
    if (fd < 0) { perror("socket"); return 1; }

    struct sockaddr_un addr;
    memset(&addr, 0, sizeof addr);
    addr.sun_family = AF_UNIX;
    strncpy(addr.sun_path, SCHCOM_SOCKET_PATH, sizeof addr.sun_path - 1);
    if (connect(fd, (struct sockaddr *)&addr, sizeof addr) < 0) {
        fprintf(stderr, "schcom-demo: connect %s: %s\n",
                SCHCOM_SOCKET_PATH, strerror(errno));
        return 1;
    }

    /* Handshake first: the compositor accepts nothing else before it. */
    struct schcom_hello hello;
    memset(&hello, 0, sizeof hello);
    hello.hdr.op     = SCHCOM_OP_HELLO;
    hello.hdr.length = sizeof hello;
    hello.hdr.serial = 1;
    hello.version    = SCHCOM_VERSION;
    if (write(fd, &hello, sizeof hello) != (ssize_t)sizeof hello) {
        perror("write hello"); return 1;
    }

    struct schcom_hello ack;
    if (read_all(fd, &ack, sizeof ack) < 0 || ack.hdr.op != SCHCOM_OP_HELLO_ACK) {
        fprintf(stderr, "schcom-demo: no hello ack\n");
        return 1;
    }
    printf("schcom-demo: connected, protocol v%u\n", ack.version);

    struct schcom_create_surface req;
    memset(&req, 0, sizeof req);
    req.hdr.op     = SCHCOM_OP_CREATE_SURFACE;
    req.hdr.length = sizeof req;
    req.hdr.serial = 2;
    req.width = w; req.height = h;
    req.x = at_x;  req.y = at_y;
    if (write(fd, &req, sizeof req) != (ssize_t)sizeof req) {
        perror("write create"); return 1;
    }

    struct schcom_surface surf;
    if (read_all(fd, &surf, sizeof surf) < 0) {
        fprintf(stderr, "schcom-demo: no reply to create\n");
        return 1;
    }
    if (surf.hdr.op != SCHCOM_OP_SURFACE) {
        fprintf(stderr, "schcom-demo: create refused (op %u)\n", surf.hdr.op);
        return 1;
    }
    if (surf.handle_kind != SCHCOM_HANDLE_SHMID) {
        fprintf(stderr, "schcom-demo: unexpected handle kind %u\n", surf.handle_kind);
        return 1;
    }

    void *pix = shmat((int)surf.handle, NULL, 0);
    if (pix == (void *)-1) { perror("shmat"); return 1; }

    printf("schcom-demo: surface %u, %ux%u stride %u\n",
           surf.hdr.surface, surf.width, surf.height, surf.stride);

    /* Draw: a solid block with a one-pixel border, so a test can tell "the
     * buffer arrived" from "the buffer arrived at the wrong offset". */
    for (uint32_t y = 0; y < surf.height; y++) {
        uint32_t *row = (uint32_t *)((unsigned char *)pix + (size_t)y * surf.stride);
        for (uint32_t x = 0; x < surf.width; x++) {
            int edge = (x == 0 || y == 0 || x == surf.width - 1 || y == surf.height - 1);
            row[x] = edge ? 0x00FFFFFF : colour;
        }
    }

    struct schcom_commit commit;
    memset(&commit, 0, sizeof commit);
    commit.hdr.op      = SCHCOM_OP_COMMIT;
    commit.hdr.length  = sizeof commit;
    commit.hdr.serial  = 3;
    commit.hdr.surface = surf.hdr.surface;
    commit.width = surf.width; commit.height = surf.height;
    if (write(fd, &commit, sizeof commit) != (ssize_t)sizeof commit) {
        perror("write commit"); return 1;
    }
    printf("schcom-demo: committed 0x%06X at %d,%d\n", colour, at_x, at_y);
    fflush(stdout);

    /* Stay alive: the surface belongs to this connection, and the compositor
     * drops it when the client goes. Exiting immediately would erase the very
     * thing the screenshot is meant to catch. */
    sleep(wait_s);
    return 0;
}