#include "AFBClient.h"

#include <cassert>
#include <cctype>
#include <cerrno>
#include <cstdio>
#include <cstdlib>
#include <cstring>

#include <atomic>
#include <mutex>

#include <unistd.h>

#include <systemd/sd-event.h>

#include <json-c/json.h>

extern "C" {
#include <afb/afb-ws-client.h>
#include <afb/afb-wsj1.h>
}

#define UNUSED(x) (void)(x)

namespace {

constexpr const int token_maxlen = 20;
constexpr const char *const wmAPI = "winman";

#ifdef NDEBUG
#define TRACE()
#define TRACEN(N)
#else
#define CONCAT_(X, Y) X##Y
#define CONCAT(X, Y) CONCAT_(X, Y)

#define TRACE() \
    ScopeTrace __attribute__((unused)) CONCAT(trace_scope_, __LINE__)(__func__)
#define TRACEN(N) \
    ScopeTrace __attribute__((unused)) CONCAT(named_trace_scope_, __LINE__)(#N)

struct ScopeTrace {
    thread_local static int indent;
    char const *f{};
    ScopeTrace(char const *func) : f(func) {
        fprintf(stderr, "%*s%s -->\n", 2 * indent++, "", this->f);
    }
    ~ScopeTrace() { fprintf(stderr, "%*s%s <--\n", 2 * --indent, "", this->f); }
};
thread_local int ScopeTrace::indent = 0;
#endif

/* called when wsj1 receives a method invocation */
void onCall(void *closure, const char *api, const char *verb,
            struct afb_wsj1_msg *msg) {
    TRACE();
    UNUSED(closure);
    int rc;
    printf("ON-CALL %s/%s:\n%s\n", api, verb,
           json_object_to_json_string_ext(afb_wsj1_msg_object_j(msg),
                                          JSON_C_TO_STRING_PRETTY));
    fflush(stdout);
    rc = afb_wsj1_reply_error_s(msg, "\"unimplemented\"", nullptr);
    if (rc < 0)
        fprintf(stderr, "replying failed: %m\n");
}

/* called when wsj1 receives an event */
void onEvent(void *closure, const char *event, afb_wsj1_msg *msg) {
    TRACE();
    UNUSED(closure);
    printf("ON-EVENT %s:\n%s\n", event,
           json_object_to_json_string_ext(afb_wsj1_msg_object_j(msg),
                                          JSON_C_TO_STRING_PRETTY));
    fflush(stdout);
}

/* called when wsj1 hangsup */
void onHangup(void *closure, afb_wsj1 *wsj1) {
    TRACE();
    UNUSED(closure);
    UNUSED(wsj1);
    printf("ON-HANGUP\n");
    fflush(stdout);
    exit(0);
}

constexpr static struct afb_wsj1_itf itf = {
    onHangup, onCall, onEvent,
};

// XXX: I am not sure this is the right thing to do though...
std::recursive_mutex dispatch_mutex;

void dispatch_internal(struct sd_event *loop) {
    std::lock_guard<std::recursive_mutex> guard(dispatch_mutex);
    TRACE();
    sd_event_run(loop, -1);
}

/// object will be json_object_put
int api_call(struct sd_event *loop, struct afb_wsj1 *wsj1, const char *verb,
             json_object *object,
             std::function<void(bool, json_object *)> onReply) {
    TRACE();

    // We need to wrap the actual onReply call once in order to
    // *look* like a normal functions pointer (std::functions<>
    // with captures cannot convert to function pointers).
    // Alternatively we could setup a local struct and use it as
    // closure, but I think it is cleaner this way.
    int call_rc = 0;
    std::atomic<bool> returned;
    returned.store(false, std::memory_order_relaxed);
    std::function<void(bool, json_object *)> wrappedOnReply =
        [&returned, &call_rc, &onReply](bool ok, json_object *j) {
            TRACEN(wrappedOnReply);
            call_rc = ok ? 0 : -EINVAL;
            // We know it failed, but there may be an explanation in the
            // json object.
            {
                TRACEN(onReply);
                onReply(ok, j);
            }
            returned.store(true, std::memory_order_release);
        };

    // make the actual call, use wrappedOnReply as closure
    int rc = afb_wsj1_call_j(
        wsj1, wmAPI, verb, object,
        [](void *closure, afb_wsj1_msg *msg) {
            TRACEN(callClosure);
            auto *onReply =
                reinterpret_cast<std::function<void(bool, json_object *)> *>(
                    closure);
            (*onReply)(!!afb_wsj1_msg_is_reply_ok(msg),
                       afb_wsj1_msg_object_j(msg));
        },
        &wrappedOnReply);

    if (rc < 0) {
        fprintf(
            stderr, "calling %s/%s(%s) failed: %m\n", wmAPI, verb,
            json_object_to_json_string_ext(object, JSON_C_TO_STRING_PRETTY));
        // Call the reply handler regardless with a NULL json_object*
        onReply(false, nullptr);
    } else {
        // We need to dispatch until "returned" got set, this is necessary
        // if events get triggered by the call (and would be dispatched before
        // the actual call-reply).
        while (!returned.load(std::memory_order_consume)) {
            dispatch_internal(loop);
        }

        // return the actual API call result
        rc = call_rc;
    }

    return rc;
}

}  // namespace

//       _                 ___                 _
//   ___| | __ _ ___ ___  |_ _|_ __ ___  _ __ | |
//  / __| |/ _` / __/ __|  | || '_ ` _ \| '_ \| |
// | (__| | (_| \__ \__ \  | || | | | | | |_) | |
//  \___|_|\__,_|___/___/ |___|_| |_| |_| .__/|_|
//                                      |_|
class AFBClient::Impl {
    friend class AFBClient;

    // This is the AFBClient interface impl
    int init(int port, char const *token);
    int dispatch();

    // WM API
    int requestSurface(const char *label);
    int activateSurface(const char *label);
    int deactivateSurface(const char *label);
    int endDraw(const char *label);

    void set_event_handler(enum EventType et,
                           std::function<void(char const *label)> f);

    Impl();
    ~Impl();

    struct afb_wsj1 *wsj1;
    struct sd_event *loop;
};

AFBClient::Impl::Impl() : wsj1{}, loop{} { TRACE(); }

AFBClient::Impl::~Impl() {
    TRACE();
    afb_wsj1_unref(wsj1);
    sd_event_unref(loop);
    loop = nullptr;
}

int AFBClient::Impl::init(int port, char const *token) {
    TRACE();
    char *uribuf = nullptr;
    int rc = -1;

    if (!token || strlen(token) > token_maxlen) {
        fprintf(stderr, "Token is invalid\n");
        rc = -EINVAL;
        goto fail;
    }

    for (char const *p = token; *p; p++) {
        if (!isalnum(*p)) {
            fprintf(stderr, "Token is invalid\n");
            rc = -EINVAL;
            goto fail;
        }
    }

    if (port < 1 && port > 0xffff) {
        fprintf(stderr, "Port is invalid\n");
        rc = -EINVAL;
        goto fail;
    }

    /* get the default event loop */
    rc = sd_event_default(&loop);
    if (rc < 0) {
        fprintf(stderr, "Connection to default event loop failed: %s\n",
                strerror(-rc));
        goto fail;
    }

    asprintf(&uribuf, "ws://localhost:%d/api?token=%s", port, token);

    /* connect the websocket wsj1 to the uri given by the first argument */
    wsj1 = afb_ws_client_connect_wsj1(
        loop, uribuf, const_cast<struct afb_wsj1_itf *>(&itf), nullptr);
    if (wsj1 == nullptr) {
        sd_event_unref(loop);
        fprintf(stderr, "Connection to %s failed: %m\n", uribuf);
        rc = -errno;
        goto fail;
    }

    return 0;

fail:
    return rc;
}

int AFBClient::Impl::dispatch() {
    std::lock_guard<std::recursive_mutex> guard(dispatch_mutex);
    return sd_event_run(loop, 1);
}

int AFBClient::Impl::requestSurface(const char *label) {
    TRACE();
    json_object *jp = json_object_new_object();
    json_object_object_add(jp, "drawing_name", json_object_new_string(label));
    int rc = -1;
    /* send the request */
    int rc2 = api_call(
        loop, wsj1, "request_surface", jp, [&rc](bool ok, json_object *j) {
            if (ok) {
                int id =
                    json_object_get_int(json_object_object_get(j, "response"));
                char *buf;
                asprintf(&buf, "%d", id);
                printf("setenv(\"QT_IVI_SURFACE_ID\", %s, 1)\n", buf);
                if (setenv("QT_IVI_SURFACE_ID", buf, 1) != 0) {
                    fprintf(stderr, "putenv failed: %m\n");
                    rc = -errno;
                } else {
                    rc = 0;  // Single point of success
                }
            } else {
                fprintf(stderr, "Could not get surface ID from WM: %s\n",
                        j ? json_object_to_json_string_ext(
                                j, JSON_C_TO_STRING_PRETTY)
                          : "no-info");
                rc = -EINVAL;
            }
        });

    return rc2 < 0 ? rc2 : rc;
}

int AFBClient::Impl::activateSurface(const char *label) {
    TRACE();
    json_object *j = json_object_new_object();
    json_object_object_add(j, "drawing_name", json_object_new_string(label));
    return api_call(loop, wsj1, "activate_surface", j, [](bool ok,
                                                          json_object *j) {
        if (!ok) {
            fprintf(
                stderr, "API Call activate_surface() failed: %s\n",
                j ? json_object_to_json_string_ext(j, JSON_C_TO_STRING_PRETTY)
                  : "no-info");
        }
    });
}

int AFBClient::Impl::deactivateSurface(const char *label) {
    TRACE();
    json_object *j = json_object_new_object();
    json_object_object_add(j, "drawing_name", json_object_new_string(label));
    return api_call(loop, wsj1, "deactivate_surface", j, [](bool ok,
                                                            json_object *j) {
        if (!ok) {
            fprintf(
                stderr, "API Call deactivate_surface() failed: %s\n",
                j ? json_object_to_json_string_ext(j, JSON_C_TO_STRING_PRETTY)
                  : "no-info");
        }
    });
}

int AFBClient::Impl::endDraw(const char *label) {
    TRACE();
    json_object *j = json_object_new_object();
    json_object_object_add(j, "drawing_name", json_object_new_string(label));
    return api_call(loop, wsj1, "enddraw", j, [](bool ok, json_object *j) {
        if (!ok) {
            fprintf(
                stderr, "API Call endDraw() failed: %s\n",
                j ? json_object_to_json_string_ext(j, JSON_C_TO_STRING_PRETTY)
                  : "no-info");
        }
    });
}

void AFBClient::Impl::set_event_handler(
    enum EventType et, std::function<void(char const *)> func) {
    UNUSED(et);
    UNUSED(func);
    TRACE();
    // XXX todo
}

//       _                    _    _____ ____   ____ _ _            _
//   ___| | __ _ ___ ___     / \  |  ___| __ ) / ___| (_) ___ _ __ | |_
//  / __| |/ _` / __/ __|   / _ \ | |_  |  _ \| |   | | |/ _ \ '_ \| __|
// | (__| | (_| \__ \__ \  / ___ \|  _| | |_) | |___| | |  __/ | | | |_
//  \___|_|\__,_|___/___/ /_/   \_\_|   |____/ \____|_|_|\___|_| |_|\__|
//
int AFBClient::init(int port, char const *token) {
    return this->d->init(port, token);
}

int AFBClient::dispatch() { return this->d->dispatch(); }

int AFBClient::requestSurface(const char *label) {
    return this->d->requestSurface(label);
}

int AFBClient::activateSurface(const char *label) {
    return this->d->activateSurface(label);
}

int AFBClient::deactivateSurface(const char *label) {
    return this->d->deactivateSurface(label);
}

int AFBClient::endDraw(const char *label) { return this->d->endDraw(label); }

void AFBClient::set_event_handler(enum EventType et,
                                  std::function<void(char const *label)> f) {
    return this->d->set_event_handler(et, std::move(f));
}

AFBClient &AFBClient::instance() {
    TRACE();
    static AFBClient obj;
    return obj;
}

AFBClient::AFBClient() : d(new Impl) {}

AFBClient::~AFBClient() { delete d; }