#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>

#include "luaradio.h"

/* Radio context */
struct luaradio {
    lua_State *L;
    char errmsg[1024];
};

luaradio_t *luaradio_new(void) {
    luaradio_t *radio;

    /* Allocate radio context */
    radio = calloc(1, sizeof(luaradio_t));
    if (radio == NULL)
        return NULL;

    /* Create a new Lua state */
    radio->L = luaL_newstate();
    if (radio->L == NULL) {
        free(radio);
        return NULL;
    }

    /* Open standard libraries */
    luaL_openlibs(radio->L);

    return radio;
}

static int lua_iscompositeblock(lua_State *L) {
    /* Check stack size */
    if (lua_gettop(L) < 1)
        return 0;

    /* Check instance of top element is CompositeBlock, i.e.,
     * call radio.class.isinstanceof(top, radio.CompositeBlock) */
    lua_getglobal(L, "radio");
    lua_getfield(L, -1, "CompositeBlock");
    lua_getfield(L, -2, "class");
    lua_getfield(L, -1, "isinstanceof");
    lua_pushvalue(L, 1);
    lua_pushvalue(L, 3);
    if (lua_pcall(L, 2, 1, 0) != 0)
        return 0;

    /* Check result is true */
    if (!(lua_isboolean(L, -1) && lua_toboolean(L, -1)))
        return 0;

    /* Pop off intermediate elements off the stack */
    lua_pop(L, 4);

    return 1;
}

static int _luaradio_traceback(lua_State *L) {
    /* Return error object directly, if it's not a string */
    if (!lua_isstring(L, 1))
        return 1;

    /* Create traceback appended to error string */
    luaL_traceback(L, L, lua_tostring(L, 1), 1);
    return 1;
}

int luaradio_load(luaradio_t *radio, const char *script) {
    /* Clear stack */
    lua_settop(radio->L, 0);

    /* Load radio module into global namespace */
    lua_pushcfunction(radio->L, _luaradio_traceback);
    lua_getglobal(radio->L, "require");
    lua_pushliteral(radio->L, "radio");
    if (lua_pcall(radio->L, 1, 1, 1) != 0)
        goto handle_error;
    /* Pop error handler */
    lua_remove(radio->L, 1);
    /* Set radio global to module */
    lua_setglobal(radio->L, "radio");

    /* Run script */
    lua_pushcfunction(radio->L, _luaradio_traceback);
    if (luaL_loadstring(radio->L, script) != 0)
        goto handle_error;
    if (lua_pcall(radio->L, 0, LUA_MULTRET, 1) != 0)
        goto handle_error;
    /* Pop error handler */
    lua_remove(radio->L, 1);

    /* Check instance of top element is CompositeBlock */
    if (!lua_iscompositeblock(radio->L)) {
        strncpy(radio->errmsg, "Script did not return a radio.CompositeBlock instance.", sizeof(radio->errmsg));
        lua_settop(radio->L, 0);
        return -1;
    }

    return 0;

    handle_error:
    /* Copy error message into context */
    strncpy(radio->errmsg, lua_tostring(radio->L, -1), sizeof(radio->errmsg));
    /* Clear stack */
    lua_settop(radio->L, 0);

    return -1;
}

int luaradio_start(luaradio_t *radio) {
    /* Check instance of top element is CompositeBlock */
    if (!lua_iscompositeblock(radio->L)) {
        strncpy(radio->errmsg, "No LuaRadio flow graph found to run.", sizeof(radio->errmsg));
        return -1;
    }

    /* Call top:start() */
    lua_pushcfunction(radio->L, _luaradio_traceback);
    lua_getfield(radio->L, -2, "start");
    lua_pushvalue(radio->L, -3);
    if (lua_pcall(radio->L, 1, 0, 2) != 0) {
        /* Copy error message into context */
        strncpy(radio->errmsg, lua_tostring(radio->L, -1), sizeof(radio->errmsg));
        /* Pop error and error handler off of stack */
        lua_pop(radio->L, 2);
        return -1;
    }
    /* Pop error handler */
    lua_remove(radio->L, 2);

    return 0;
}

int luaradio_status(luaradio_t *radio, bool *running) {
    /* Check instance of top element is CompositeBlock */
    if (!lua_iscompositeblock(radio->L)) {
        strncpy(radio->errmsg, "No LuaRadio flow graph found to check status of.", sizeof(radio->errmsg));
        return -1;
    }

    /* Call top:status() */
    lua_pushcfunction(radio->L, _luaradio_traceback);
    lua_getfield(radio->L, -2, "status");
    lua_pushvalue(radio->L, -3);
    if (lua_pcall(radio->L, 1, 1, 2) != 0) {
        /* Copy error message into context */
        strncpy(radio->errmsg, lua_tostring(radio->L, -1), sizeof(radio->errmsg));
        /* Pop error and error handler off of stack */
        lua_pop(radio->L, 2);
        return -1;
    }
    /* Pop error handler */
    lua_remove(radio->L, 2);

    /* Extract boolean value under "running" key */
    lua_getfield(radio->L, -1, "running");
    *running = lua_toboolean(radio->L, -1);
    lua_pop(radio->L, 2);

    return 0;
}

int luaradio_wait(luaradio_t *radio, bool *success) {
    /* Check instance of top element is CompositeBlock */
    if (!lua_iscompositeblock(radio->L)) {
        strncpy(radio->errmsg, "No LuaRadio flow graph found to wait on.", sizeof(radio->errmsg));
        return -1;
    }

    /* Call top:wait() */
    lua_pushcfunction(radio->L, _luaradio_traceback);
    lua_getfield(radio->L, -2, "wait");
    lua_pushvalue(radio->L, -3);
    if (lua_pcall(radio->L, 1, 1, 2) != 0) {
        /* Copy error message into context */
        strncpy(radio->errmsg, lua_tostring(radio->L, -1), sizeof(radio->errmsg));
        /* Pop error and error handler off of stack */
        lua_pop(radio->L, 2);
        return -1;
    }

    /* Populate success */
    if (success) *success = lua_toboolean(radio->L, -1);

    /* Pop error handler and result */
    lua_pop(radio->L, 2);

    return 0;
}

int luaradio_stop(luaradio_t *radio, bool *success) {
    /* Check instance of top element is CompositeBlock */
    if (!lua_iscompositeblock(radio->L)) {
        strncpy(radio->errmsg, "No LuaRadio flow graph found to stop.", sizeof(radio->errmsg));
        return -1;
    }

    /* Call top:stop() */
    lua_pushcfunction(radio->L, _luaradio_traceback);
    lua_getfield(radio->L, -2, "stop");
    lua_pushvalue(radio->L, -3);
    if (lua_pcall(radio->L, 1, 1, 2) != 0) {
        /* Copy error message into context */
        strncpy(radio->errmsg, lua_tostring(radio->L, -1), sizeof(radio->errmsg));
        /* Pop error and error handler off of stack */
        lua_pop(radio->L, 2);
        return -1;
    }

    /* Populate success */
    if (success) *success = lua_toboolean(radio->L, -1);

    /* Pop error handler and result */
    lua_pop(radio->L, 2);

    return 0;
}

void luaradio_free(luaradio_t *radio) {
    /* Close Lua state */
    lua_close(radio->L);

    /* Free radio context */
    free(radio);
}

lua_State *luaradio_get_state(luaradio_t *radio) {
    if (radio == NULL)
        return NULL;

    return radio->L;
}

const char *luaradio_strerror(luaradio_t *radio) {
    if (radio == NULL)
        return "Memory allocation error.";

    return radio->errmsg;
}

const char *luaradio_version(void) {
    #define _STRINGIFY(s) #s
    #define STRINGIFY(s) _STRINGIFY(s)
    return "v" STRINGIFY(VERSION_MAJOR) "." STRINGIFY(VERSION_MINOR) "." STRINGIFY(VERSION_PATCH);
}

unsigned int luaradio_version_number(void) {
    return VERSION_MAJOR*10000 + VERSION_MINOR*100 + VERSION_PATCH;
}

const luaradio_version_t *luaradio_version_info(void) {
    static luaradio_version_t version = {
        .major = VERSION_MAJOR,
        .minor = VERSION_MINOR,
        .patch = VERSION_PATCH,
        .commit_id = VERSION_COMMIT,
    };
    return &version;
}