/**
 * @file addons/app.c
 * @brief App addon.
 */

#include "../private_api.h"

#ifdef FLECS_APP

static
int flecs_default_run_action(
    ecs_world_t *world,
    ecs_app_desc_t *desc)
{
    if (desc->init) {
        desc->init(world);
    }

    int result = 0;
    if (desc->frames) {
        int32_t i;
        for (i = 0; i < desc->frames; i ++) {
            if ((result = ecs_app_run_frame(world, desc)) != 0) {
                break;
            }
        }
    } else {
        while ((result = ecs_app_run_frame(world, desc)) == 0) { }
    }

    /* Ensure quit flag is set on world, which can be used to determine if
     * world needs to be cleaned up. */
#ifndef __EMSCRIPTEN__
    ecs_quit(world);
#endif

    if (result == 1) {
        return 0; /* Normal exit */
    } else {
        return result; /* Error code */
    }
}

static
int flecs_default_frame_action(
    ecs_world_t *world,
    const ecs_app_desc_t *desc)
{
    return !ecs_progress(world, desc->delta_time);
}

static ecs_app_run_action_t run_action = flecs_default_run_action;
static ecs_app_frame_action_t frame_action = flecs_default_frame_action;
static ecs_app_desc_t ecs_app_desc;

/* Serve REST API from wasm image when running in emscripten */
#ifdef ECS_TARGET_EM
#include <emscripten.h>

ecs_http_server_t *flecs_wasm_rest_server = NULL;

EMSCRIPTEN_KEEPALIVE
char* flecs_explorer_request(const char *method, char *request, char *body) {
    ecs_assert(flecs_wasm_rest_server != NULL, ECS_INVALID_OPERATION,
        "wasm REST server is not initialized yet");

    ecs_http_reply_t reply = ECS_HTTP_REPLY_INIT;
    ecs_http_server_request(
        flecs_wasm_rest_server, method, request, body, &reply);
    if (reply.code == 200) {
        return ecs_strbuf_get(&reply.body);
    } else {
        char *body = ecs_strbuf_get(&reply.body);
        if (body) {
            return body;
        } else {
            return flecs_asprintf(
                "{\"error\": \"bad request\", \"status\": %d}", reply.code);
        }
    }
}
#endif

int ecs_app_run(
    ecs_world_t *world,
    ecs_app_desc_t *desc)
{
    ecs_app_desc = *desc;

#ifndef ECS_TARGET_EM
    if (ECS_NEQZERO(ecs_app_desc.target_fps)) {
        ecs_set_target_fps(world, ecs_app_desc.target_fps);
    }
    if (ecs_app_desc.threads) {
        ecs_set_threads(world, ecs_app_desc.threads);
    }
#endif

    /* REST server enables connecting to app with explorer */
    if (desc->enable_rest) {
#ifdef FLECS_REST
#ifdef ECS_TARGET_EM
        flecs_wasm_rest_server = ecs_rest_server_init(world, NULL);
        ecs_assert(flecs_wasm_rest_server != NULL, ECS_INTERNAL_ERROR, 
            "failed to create wasm REST server (unexpected error)");
#else
        ECS_IMPORT(world, FlecsRest);
        ecs_set(world, EcsWorld, EcsRest, {.port = desc->port });
#endif
#else
        ecs_warn("cannot enable remote API, REST addon not available");
#endif
    }

    /* Monitoring periodically collects statistics */
    if (desc->enable_stats) {
#ifdef FLECS_STATS
        ECS_IMPORT(world, FlecsStats);
#else
        ecs_warn("cannot enable monitoring, MONITOR addon not available");
#endif
    }

    return run_action(world, &ecs_app_desc);
}

int ecs_app_run_frame(
    ecs_world_t *world,
    const ecs_app_desc_t *desc)
{
    return frame_action(world, desc);
}

int ecs_app_set_run_action(
    ecs_app_run_action_t callback)
{
    if (run_action != flecs_default_run_action && run_action != callback) {
        ecs_err("run action already set");
        return -1;
    }

    run_action = callback;

    return 0;
}

int ecs_app_set_frame_action(
    ecs_app_frame_action_t callback)
{
    if (frame_action != flecs_default_frame_action && frame_action != callback) {
        ecs_err("frame action already set");
        return -1;
    }

    frame_action = callback;

    return 0;
}

#endif