#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>

#define EXIT_LOGFILE_HANDLING 2
#define EXIT_LUAFILE_HANDLING 3

void trim(char *string) {
    if (strlen(string) > 0 && string[strlen(string) - 1] == '\n') {
        string[strlen(string) - 1] = '\0';
        trim(string);
    }
}

int luaFilterCall(lua_State *L, char *line, size_t len) {
    int filter;

    lua_getglobal(L, "filter");
    lua_pushlstring(L, line, len);
    if (lua_pcall(L, 1, 1, 0) != 0) {
        fprintf(stderr, "Error running LUA function 'filter': %s\n", lua_tostring(L, -1));
        exit(EXIT_LUAFILE_HANDLING);
    }

    if (!lua_isboolean(L, -1)) {
        fprintf(stderr, "LUA function 'filter' did not return a boolean");
        exit(EXIT_LUAFILE_HANDLING);
    }

    filter = lua_toboolean(L, -1);
    lua_pop(L, 1);

    return filter;
}

const char* luaFormatCall(lua_State *L, char *line, size_t len, size_t *formatLen) {
    lua_getglobal(L, "format");
    lua_pushlstring(L, line, len);
    if (lua_pcall(L, 1, 1, 0) != 0) {
        fprintf(stderr, "Error running LUA function 'format': %s\n", lua_tostring(L, -1));
        exit(EXIT_LUAFILE_HANDLING);
    }

    if (!lua_isstring(L, -1)) {
        fprintf(stderr, "LUA function 'format' did not return a string\n");
        exit(EXIT_LUAFILE_HANDLING);
    }

    return lua_tolstring(L, -1 , formatLen);
}

static int luaColor(lua_State *L) {
    size_t strLen, colorLen;
    const char *str, *color;
    str = luaL_checklstring(L, 1, &strLen);
    color = luaL_checklstring(L, 2, &colorLen);
    int retLen = strLen + colorLen + 7;
    char ret[retLen];
    sprintf(ret, "\033[%sm%s\033[0m", color, str);
    
    lua_pushlstring(L, ret, retLen);

    return 1;
}

int main(int argc, char *argv[]) {
    if (argc != 3) {
        fprintf(stderr, "Usage: %s <lua file> <log file>\n", argv[0]);
        return 1;
    }

    int status;
    char *logfile = argv[2];
    char *luafile = argv[1];
    char *line = NULL;
    size_t len = 0;
    ssize_t bytesRead;
    FILE *fp;
    lua_State *L;
    L = luaL_newstate();
    luaL_openlibs(L);

    fp = fopen(logfile, "r");
    if (errno) {
        fprintf(stderr, "Error opening file %s: %s\n", logfile, strerror(errno));
        return EXIT_LOGFILE_HANDLING;
    }

    status = luaL_dofile(L, luafile);
    if (status) {
        fprintf(stderr, "Error reading LUA file %s: %s\n", luafile, lua_tostring(L, -1));
        return EXIT_LUAFILE_HANDLING;
    }

    lua_pushcfunction(L, luaColor);
    lua_setglobal(L, "color");

    while ((bytesRead = getline(&line, &len, fp)) != -1) {
        size_t formatLen;
        const char *formatLine;
        
        trim(line);

        if (luaFilterCall(L, line, bytesRead)) {
            continue;
        }

        formatLine = luaFormatCall(L, line, bytesRead, &formatLen);
        printf("%s\n", formatLine);
    }
    if (errno) {
        fprintf(stderr, "Error reading file %s: %s\n", logfile, strerror(errno));
        return EXIT_LOGFILE_HANDLING;
    }

    free(line);
    lua_close(L);

    fclose(fp);
}