/*
 *  runfile - rf
 *
 *  a no-dependancy, minimal
 *  POSIX C99 Make/justfile
 *  alternative to run commands.
 *
 *             czjstmax
 *   <jstmaxlol at
 *      disroot dot org>
 *
 *  check MAINTAINERS file
 */

#define _POSIX_C_SOURCE 200809L

#define RUNFILE_VER_MAJ 1
#define RUNFILE_VER_MIN 3
#define RUNFILE_VER_FIX 0

/*
 *> rfile version system
 * VER_MAX : anything that changes how rfile are written in the slightest
 *           between 0 and 999
 * VER_MIN : anything that varies the UX of the program (i.e. CLI flags)
 *           between 0 and 999
 * VER_FIX : optimizations, slight logic tweaks, anything that is not
 *            noticeable by the user but impacts the dev experience enough
 *            to be important. between 0 and 9999
 */

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdbool.h>
#include <wordexp.h>
#include <sys/wait.h>

#define MAX_VARS 128

typedef struct {
    char *key;
    char *val;
} var_t;

var_t vars[MAX_VARS];
size_t var_count = 0;

void usage();
void printBox(char *str);
char *expand_vars(char *input);

int main(int argc, char **argv)
{
    char *section = NULL;
    bool in_section = false;

    if (argc >= 2) {
        for (int i = 1; i < argc; i++) {
            if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
                usage();
                return 0;
            }
        }
    }

    FILE *f = fopen("rfile", "r");

    if (!f) {
        fprintf(stderr, "no rfile found.\n");
        return 1;
    }

    wordexp_t p;
    char *line = NULL;
    size_t len = 0;

    while (getline(&line, &len, f) != -1) {
        line[strcspn(line, "\n")] = '\0';
        char *cmd = line;

        while (isspace(*cmd))
            cmd++;

        if (*cmd == '\0')
            continue;
        else if (cmd[0] == '#') /* TODO: strchr() up to # and trim cmd to only skip
                                   the commented-out part to allow in-line comments */
            continue;
        #if defined(RF_EXTRAS) || defined(RF_EXTRA_MORE_COMMENTS)
        else if (strncmp(cmd, "// ", 3) == 0)
            continue;
        else if (strncmp(cmd, "-- ", 3) == 0)
            continue;
        #endif
        else if (strcmp(cmd, "}") == 0 || strcmp(line, "}") == 0) {
            in_section = false;

            free(section);
            section = NULL;

            continue;
        }
        if (cmd[0] == '@' && strchr(cmd, '=')) {
            char *eq = strchr(cmd, '=');

            *eq = '\0';

            char *key = cmd + 1; //skip '@'
            char *val = eq + 1;

            vars[var_count].key = strdup(key);
            vars[var_count].val = strdup(val);
            var_count++;

            continue;
        }

        char *brace = strchr(cmd, '{');
        if (brace) {
            *brace = '\0';

            size_t l = strlen(cmd);

            while (l > 0 && (cmd[l-1] == ' ' || cmd[l-1] == '\t')) {
                cmd[l-1] = '\0';
                l--;
            }

            free(section);
            section = strdup(cmd);
            in_section = true;

            continue;
        }

        bool matches =
            (argc == 1 && !in_section)
            || (argc > 1 && section && strcmp(argv[1], section) == 0);

        if (!matches)
            continue;

        if (strncmp(cmd, "@: ", 3) == 0) {
            printf("\n%s\n", cmd);
            continue;
        }
        else if (strncmp(cmd, "@:! ", 4) == 0) {
            printBox(cmd);
            continue;
        }

        char *expanded = expand_vars(cmd);

        #if !defined(RF_HIDDEN_CMD)
        printf("$ %s\n", expanded);
        #endif

        if (wordexp(expanded, &p, 0) != 0) {
            fprintf(stderr, "wordexp failed\n");
            continue;
        }

        pid_t pid = fork();
        if (pid == 0) {
            execvp(p.we_wordv[0], p.we_wordv);

            perror("failed to run command");

            fclose(f);
            _exit(1);
        }

        waitpid(pid, NULL, 0);
        wordfree(&p);
    }

    free(line);
    fclose(f);
    return 0;
}

void usage()
{
    printf(
        "runfile usage - version %d.%d.%d\n"
        "syn: rf [section]\n"
        , RUNFILE_VER_MAJ, RUNFILE_VER_MIN, RUNFILE_VER_FIX
    );
}

char *expand_vars(char *input)
{
    static char buf[8192];
    size_t bi = 0;

    for (size_t i = 0; input[i] && bi < sizeof(buf) - 1; i++) {

        if (input[i] == '@') {

            char name[128] = {0};
            size_t ni = 0;
            size_t j = i + 1;

            while (input[j] &&
                   !isspace(input[j]) &&
                   input[j] != '@' &&
                   ni < sizeof(name) - 1) {
                name[ni++] = input[j++];
            }

            name[ni] = '\0';

            const char *replacement = NULL;
            for (size_t v = 0; v < var_count; v++) {
                if (strcmp(vars[v].key, name) == 0) {
                    replacement = vars[v].val;
                    break;
                }
            }

            if (replacement) {
                size_t k = 0;
                while (replacement[k] && bi < sizeof(buf) - 1)
                    buf[bi++] = replacement[k++];
            }
            else {
                buf[bi++] = '@';
                for (size_t k = 0; name[k]; k++)
                    buf[bi++] = name[k];
            }

            i = j - 1;
            continue;
        }

        buf[bi++] = input[i];
    }

    buf[bi] = '\0';
    return buf;
}

void printBox(char *str)
{	
	printf("┌");
	for (size_t i = 0; i < strlen(str) + 2; ++i)
		printf("─");
	printf("┐\n");

	printf("│ %s │\n", str);

	printf("└");
	for (size_t i = 0; i < strlen(str) + 2; ++i)
		printf("─");
	printf("┘\n");
}