/* This entire file is licensed under MIT
 *
 * Copyright 2020 Sophie Winter
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include "mock-server.h"

#include <fcntl.h>
#include <sys/stat.h>

struct wl_display* display = NULL;

static void open_command_stream();

static const char* get_display_name() {
    const char* result = getenv("WAYLAND_DISPLAY");
    if (!result) {
        FATAL("WAYLAND_DISPLAY not set");
    }
    return result;
}

struct request_override_t {
    const struct wl_message* message;
    request_override_function_t function;
    struct wl_list link;
};

struct wl_list request_overrides;

void install_request_override(
    const struct wl_interface* interface,
    const char* name,
    request_override_function_t function
) {
    for (int i = 0; i < interface->method_count; i++) {
        if (strcmp(name, interface->methods[i].name) == 0) {
            struct request_override_t* override = calloc(1, sizeof(struct request_override_t));
            override->message = &interface->methods[i];
            override->function = function;
            wl_list_insert(&request_overrides, &override->link);
            return;
        }
    }
    FATAL_FMT("Interface %s does not have a request named %s", interface->name, name);
}

static int default_dispatcher(
    const void* data,
    void* resource,
    uint32_t opcode,
    const struct wl_message* message,
    union wl_argument* args
) {
    struct wl_resource* created = NULL;

    // If there is a new-id type argument, a resource needs to be created for it
    // See https://wayland.freedesktop.org/docs/html/apb.html#Client-structwl__message
    int arg = 0;
    for (const char* c = message->signature; *c; c++) {
        if (*c == 'n' && args[arg].n != 0) {
            created = wl_resource_create(
                wl_resource_get_client(resource),
                message->types[arg],
                wl_resource_get_version(resource),
                args[arg].n);
            use_default_impl(created);
            break;
        }
        if (*c >= 'a' && *c <= 'z')
            arg++;
    }

    struct request_override_t* override;
    wl_list_for_each(override, &request_overrides, link) {
        if (override->message == message) {
            override->function(resource, message, created, args);
            break;
        }
    }

    if (strcmp(message->name, "destroy") == 0) {
        wl_resource_destroy(resource);
    }
    return 0;
}

void use_default_impl(struct wl_resource* resource) {
    wl_resource_set_dispatcher(resource, default_dispatcher, NULL, NULL, NULL);
}

static void default_global_bind(struct wl_client* client, void* data, uint32_t version, uint32_t id) {
    struct wl_interface* interface = data;
    struct wl_resource* resource = wl_resource_create(client, interface, version, id);
    use_default_impl(resource);
};

void default_global_create(struct wl_display* display, const struct wl_interface* interface, int version) {
    wl_global_create(display, interface, version, (void*)interface, default_global_bind);
}

char type_code_at_index(const struct wl_message* message, int index) {
    int i = 0;
    for (const char* c = message->signature; *c; c++) {
        if (*c >= 'a' && *c <= 'z') {
            if (i == index)
                return *c;
            else
                i++;
        }
    }
    FATAL_FMT(".%s does not have an argument %d", message->name, index);
}

static void client_disconnect(struct wl_listener *listener, void *data) {
    wl_display_terminate(display);
}

static struct wl_listener client_disconnect_listener = {
    .notify = client_disconnect,
};

static void client_connect(struct wl_listener *listener, void *data) {
    struct wl_client* client = (struct wl_client*)data;
    wl_client_add_destroy_listener(client, &client_disconnect_listener);
}

static struct wl_listener client_connect_listener = {
    .notify = client_connect,
};


static void send_command_response(char* command) {
    const char* fifo_path = getenv("SERVER_TO_CLIENT_FIFO");
    ASSERT(fifo_path);
    int fd;
    ASSERT((fd = open(fifo_path, O_WRONLY)) >= 0);
    const char* argv[20] = {command};
    int argc = 1;
    while (*command) {
        if (*command == ' ') {
            *command = '\0';
            argv[argc] = command + 1;
            argc++;
        }
        command++;
    }
    const char* response = handle_command(argv);
    ASSERT(write(fd, response, strlen(response)) > 0);
    ASSERT(write(fd, "\n", 1) > 0);
    close(fd);
}

static int read_command_stream(int fd, uint32_t mask, void *data) {
#define BUFFER_SIZE 1024
    static char buffer[BUFFER_SIZE];
    static int length = 0;

    while (true) {
        ASSERT(length < BUFFER_SIZE);
        char* c = buffer + length;
        ssize_t bytes_read = read(fd, c, 1);
        if (bytes_read == -1) {
            return 0;
        } else if (bytes_read == 0) {
            close(fd);
            open_command_stream();
            return 0;
        } else if (*c == '\n') {
            *c = '\0';
            length = 0;
            send_command_response(buffer);
        } else {
            length++;
        }
    }

#undef BUFFER_SIZE
}

static void open_command_stream() {
    static struct wl_event_source* event_source = NULL;
    if (event_source) {
        wl_event_source_remove(event_source);
    }
    const char* fifo_path = getenv("CLIENT_TO_SERVER_FIFO");
    ASSERT(fifo_path);
    int fd;
    mkfifo(fifo_path, 0666);
    ASSERT((fd = open(fifo_path, O_RDONLY | O_NONBLOCK)) >= 0);
    event_source = wl_event_loop_add_fd(
        wl_display_get_event_loop(display),
        fd,
        WL_EVENT_READABLE,
        read_command_stream,
        NULL
    );
}

int main(int argc, const char** argv) {
    wl_list_init(&request_overrides);

    display = wl_display_create();
    if (wl_display_add_socket(display, get_display_name()) != 0) {
        FATAL_FMT("server failed to connect to Wayland display %s", get_display_name());
    }

    open_command_stream();

    wl_display_add_client_created_listener(display, &client_connect_listener);

    init();

    wl_display_run(display);
    wl_display_destroy(display);

    return 0;
}