#include "args.h"
#include "command.h"
#include "lslib.h"

#include <stdlib.h>
#include <sys/types.h>
#include <pwd.h>
#include <unistd.h>
#include <dirent.h>
#include <errno.h>
#include <string.h>

enum method {
    ADD,
    SUB,
    SET
};

static struct {
    bool recurse;
    bool list_changed;
    bool verbose;
    bool quiet;
    enum method method;
    mode_t mode;
} flags;

static void help (void) {
    printf("Usage: chmod [-Rcvf] MODE[,MODE]... FILE...\n\n");
    printf("MODE is octal number (bit pattern sstrwxrwxrwx) or [ugoa]{+|-|=}[rwxXst]\n\n");
    printf("\t-R\tRecurse\n");
	printf("\t-c\tList changed files\n");
	printf("\t-v\tVerbose\n");
	printf("\t-f\tHide errors\n");
}

static int short_arg(char c, char* next) {
    UNUSED(next);
    switch (c) {
        case 'R':
            flags.recurse = true;
            break;
        case 'c':
            flags.list_changed = true;
            break;
        case 'v':
            flags.verbose = true;
            break;
        case 'f':
            flags.quiet = true;
            break;
        case 'r':
        case 'w':
        case 'x':
        case 'X':
        case 't':
        case 's':
            return ARG_IGNORE;
        default:
            return ARG_INVALID;
    }
    return ARG_UNUSED;
}

static void chmod_file(char* path) {
    int save;
    struct stat s;
    DIR* d;
    struct dirent* file;
    mode_t mode = 0;

    save = push_path_buffer(path);
    
    if (lstat(get_path_buffer(), &s) < 0) {
        if (!flags.quiet) {
            error_s("cannot stat '%s': %s", get_path_buffer(), strerror(errno));
        }
        pop_path_buffer(save);
        return;
    }

    if (flags.method == SET) {
        mode = flags.mode;;
    } else if (flags.method == ADD) {
        mode = s.st_mode | flags.mode;
    } else if (flags.method == SUB) {
        mode = s.st_mode & ~flags.mode;
    }
    
    if (chmod(get_path_buffer(), mode) < 0) {
        if (!flags.quiet) {
            error_s("cannot chmod '%s': %s", get_path_buffer(), strerror(errno));
        }
        pop_path_buffer(save);
        return;
    } else if (flags.list_changed) {
        printf("chmod: changed '%s' to %o\n", get_path_buffer(), mode);
    }

    if (!flags.recurse) {
        pop_path_buffer(save);
        return;
    }

    if (!S_ISDIR(s.st_mode)) {
        pop_path_buffer(save);
        return;
    }

    d = opendir(get_path_buffer());
    if (d == NULL) {
        if (!flags.quiet) {
            error_s("cannot open dir '%s': %s", get_path_buffer(), strerror(errno));
        }
        pop_path_buffer(save);
        return;
    }

    while ((file = readdir(d)) != NULL) {
        if (is_dot_dir(file->d_name)) continue;
        chmod_file(file->d_name);
    }
    
    closedir(d);
    pop_path_buffer(save);
}

static mode_t parse_mode(char** input) {
    mode_t mode = 00000;
    char* str = *input;

    switch (*str) {
        case '=':
            flags.method = SET;
            break;
        case '+':
            flags.method = ADD;
            break;
        case '-':
            flags.method = SUB;
            break;
        default:
            flags.method = SET;
            mode = get_mode(str);
            goto end;
    }

next:
    str++;
    switch (*str) {
        case 'r':
            mode |= 00444;
            goto next;
        case 'w':
            mode |= 00200;
            goto next;
        case 'x':
            mode |= 00111;
            goto next;
        case 'X':
            mode |= 00000;
            goto next;
        case 's':
            mode |= 06000;
            goto next;
        case 't':
            mode |= 01000;
            goto next;
        case '\0':
        case ',':
            goto end;
        default:
            error("invalid option: %c", *str);
    }

end:
    while (true) {
        
        if (*str == '\0') {
            *input = NULL;
            break;
        }

        if (*str == ',') {
            *input = ++str;
            break;
        }

        str++;
    }

    return mode;
}

COMMAND(chmod_cmd) {
    
    int start, i;
    
    flags.recurse = false;
    flags.list_changed = false;
    flags.verbose = false;
    flags.quiet = false;
    flags.mode = 0;

    start = parse_args(argc, argv, help, short_arg, NULL);

    if (argc - start < 1) {
        if (!flags.quiet) {
            error("no mode provided");
        } else {
            return EXIT_FAILURE;
        }
    }

    do {
        flags.mode |= parse_mode(&argv[start]);
    } while (argv[start] != NULL);

    if (argc - start < 2) {
        if (!flags.quiet) {
            error("no files passed");
        } else {
            return EXIT_FAILURE;
        }
    }

    for (i = start + 1; i < argc; i++) {
        chmod_file(argv[i]);
    }

    return EXIT_SUCCESS;
}