#include "../command.h"

#include <grp.h>
#include <pwd.h>
#include <dirent.h>
#include <ftw.h>
#include <limits.h>

#define FILE_COLOR      ANSCII BLACK COLOR
#define DIR_COLOR       ANSCII BOLD NEXT NORMAL BLUE COLOR
#define DIR_COLOR_EXEC  ANSCII BACKGROUND GREEN  NEXT NORMAL BLACK COLOR
#define LINK_COLOR      ANSCII BOLD NEXT HIGHLIGHT TURQUOISE COLOR
#define SET_UID_COLOR   ANSCII BACKGROUND RED NEXT NORMAL WHITE COLOR
#define SET_GID_COLOR   ANSCII BACKGROUND YELLOW NEXT NORMAL BLACK COLOR
#define EXEC_COLOR      ANSCII BOLD NEXT NORMAL GREEN COLOR
#define BLK_COLOR       ANSCII BOLD NEXT NORMAL YELLOW COLOR

static struct {
    bool hidden;
    bool hide_dot;
    bool more_info;
    bool one_column;
    bool recurse;
    enum When colored;
} flags;

struct FileInfo {
    struct passwd* usr;
    struct group* grp;
    char name[PATH_MAX];
    char date[13];
    char mode[11];
    char size[5];
    int links;
    bool set_uid;
    bool set_gid;
    bool exec;
    unsigned char type;
};

struct FileListInfo {
    int max_link;
    int max_usr;
    int max_grp;
    int max_size;
    int max_name;
    int total_len;
};

static DIR* get_directory(char* path) {
    DIR* d = opendir(path);
    if (d == NULL) {
        if (errno == ENOTDIR) {
            printf("\x1b[0m%s is a a file\n", path);
        } else {
            printf("\x1b[0merror: failed to open directory '%s': %s\n", path, strerror(errno));
        }
    }
    return d;
}

static void append_path(char buf[PATH_MAX], const char* dir_path, const char* file_path) {
    size_t dir_len = strlen(dir_path);
    size_t file_len = strlen(file_path);

    memcpy(buf, dir_path, dir_len);
    if (buf[dir_len-1] != '/') {
        buf[dir_len] = '/';
        dir_len++;
    }
    memcpy(buf + dir_len, file_path, file_len);
    buf[dir_len + file_len] = '\0';
}

static bool get_file_info(const char* file_path, const char* dir_path, struct FileInfo* info) {

    uid_t uid = getuid();
    gid_t gid = getgid();

    char buf[PATH_MAX];
    append_path(buf, dir_path, file_path);
        
    struct stat s;
    memset(&s, 0, sizeof(struct stat));

    if (lstat(buf, &s) < 0) {
        printf("\x1b[0merror: failed to read file '%s': %s\n", buf, strerror(errno));
        return false;
    }
     
    int ty = (s.st_mode & S_IFMT) >> 12;
    
    info->set_uid = false;
    info->set_gid = false;
    info->exec = false;
    info->name[0] = '\0';

    switch (ty) {
        case DT_BLK:
            info->mode[0] = 'b';
            break;
        case DT_CHR:
            info->mode[0] = 'c';
            break;
        case DT_DIR:
            info->mode[0] = 'd';
            break;
        case DT_FIFO:
            info->mode[0] = 'f';
            break;
        case DT_LNK:
            info->mode[0] = 'l';
            break;
        case DT_SOCK:
            info->mode[0] = 's';
            break;
        case DT_UNKNOWN:
            info->mode[0] = 'u';
            break;
        case DT_WHT:
            info->mode[0] = 'w';
            break;
        default:
            info->mode[0] = '-';
            break;
    }
    
    info->mode[1] = (s.st_mode & S_IRUSR) ? 'r' : '-';
    info->mode[2] = (s.st_mode & S_IWUSR) ? 'w' : '-';
    if (s.st_mode & S_IXUSR) {
        if (s.st_mode & S_ISUID) {
            info->mode[3] = 's';
            info->set_uid = true;
        } else {
            info->mode[3] = 'x';
        }
        if (!info->exec) info->exec = s.st_uid == uid;
    } else {
        info->mode[3] = '-';
    }

    info->mode[4] = (s.st_mode & S_IRGRP) ? 'r' : '-';
    info->mode[5] = (s.st_mode & S_IWGRP) ? 'w' : '-';
    if (s.st_mode & S_IXGRP) {
        if (s.st_mode & S_ISGID) {
            info->mode[6] = 's';
            info->set_gid = true;
        } else {
            info->mode[6] = 'x';
        }
        if (!info->exec) info->exec = s.st_gid == gid;
    } else {
        info->mode[6] = '-';
    }

    info->mode[7] = (s.st_mode & S_IROTH) ? 'r' : '-';
    info->mode[8] = (s.st_mode & S_IWOTH) ? 'w' : '-';
    if (s.st_mode & S_IXOTH) {
        info->mode[9] = 'x';
        info->exec = true;
    } else {
        info->mode[9] = '-';
    }

    info->mode[10] = '\0';

    info->usr = getpwuid(s.st_uid);
    info->grp = getgrgid(s.st_gid);
    info->links = s.st_nlink;
    info->type = ty;

    strcpy(info->name, file_path);

    print_file_size(s.st_size, info->size);
    print_date_time(s.st_mtim.tv_sec + s.st_mtim.tv_nsec / 1000000000, info->date);
    return true;
}

static char* get_file_color(struct FileInfo* info) {
    char* color;
    if (info->type == DT_DIR) {
        if (info->mode[8] == 'w') {
            color = DIR_COLOR_EXEC;
        } else {
            color = DIR_COLOR;
        }
    } else if (info->type == DT_LNK) {
        color = LINK_COLOR;
    } else if (
        info->type == DT_CHR || 
        info->type == DT_BLK ||
        info->type == DT_SOCK 
    ) {
        color = BLK_COLOR;
    } else {
        if (info->set_uid) {
            color = SET_UID_COLOR;
        } else if (info->set_gid) {
            color = SET_GID_COLOR;
        } else if (info->exec) {
            color = EXEC_COLOR;
        } else {
            color = FILE_COLOR;
        }
    }
    return color;
}

static void list_files(struct FileInfo* files, int file_len, struct FileListInfo info, const char* dir_path) {
    struct winsize w;
    ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);

    if (!isatty(1)) {
        flags.one_column = true;
        if (flags.colored == AUTO)
            flags.colored = NO;
    }

    char* color;
    const int column_width = info.max_name + 1;
    const int row_count = w.ws_col / column_width;

    for (int i = 0; i < file_len; i++) {
        struct FileInfo finfo = files[i];
        color = get_file_color(&finfo);
        if (flags.more_info) {
            printf("%s %*d %*s %*s %*s %s %s%s%s", 
                finfo.mode, 
                info.max_link,
                finfo.links,
                info.max_usr,
                finfo.usr->pw_name,
                info.max_grp,
                finfo.grp->gr_name, 
                info.max_size,
                finfo.size, 
                finfo.date,
                flags.colored != NO ? color : "",
                finfo.name,
                flags.colored != NO ? "\x1b[0m" : ""
            );
            if (finfo.type == DT_LNK) {
                char path[PATH_MAX];
                append_path(path, dir_path, finfo.name);

                char lnk[PATH_MAX];
                ssize_t n;
                if ((n = readlink(path, lnk, PATH_MAX)) != -1) {
                    printf(" -> %.*s\n", (int)n, lnk);
                } else {
                    putchar('\n');
                }
            
            } else {
                putchar('\n');
            }
        } else if (flags.one_column) {
            printf("%s%s%s\n", flags.colored != NO ? color : "", finfo.name, flags.colored != NO ? "\x1b[0m" : "");
        } else {
            if (info.total_len > w.ws_col) {
                if (i != 0 && i % row_count == 0) putchar('\n');
                printf("%s%*s%s", flags.colored != NO ? color : "", -column_width, 
                       finfo.name, flags.colored != NO ? "\x1b[0m" : "");
            } else {
                printf("%s%s%s  ", flags.colored != NO ? color : "", finfo.name,
                       flags.colored != NO ? "\x1b[0m" : "");
            }
        }
    }

    if (!flags.more_info) printf("\n");
}

static bool is_dot_dir(const char* path) {
    return streql(path, ".") || streql(path, "..");
}

static int num_places (int n) {
    int r = 1;
    if (n < 0) n = (n == INT_MIN) ? INT_MAX: -n;
    while (n > 9) {
        n /= 10;
        r++;
    }
    return r;
}

static void push_file(
    struct FileInfo** files, 
    struct FileListInfo* info, 
    int* size, int* capacity, 
    const char* file_path, 
    const char* dir_path
) {

    struct FileInfo finfo;
    if (!get_file_info(file_path, dir_path, &finfo)) return;

    if (*size == *capacity) {
        *capacity *= 2;
        *files = realloc(*files, sizeof(struct FileInfo) * *capacity);
    }
    int user_len = strlen(finfo.usr->pw_name);
    if (user_len > info->max_usr) info->max_usr = user_len;

    int group_len = strlen(finfo.grp->gr_name);
    if (group_len > info->max_grp) info->max_grp = group_len;

    int name_len = strlen(file_path);
    if (name_len > info->max_name) info->max_name = name_len;

    int size_len = strlen(finfo.size);
    if (size_len > info->max_size) info->max_size = size_len;

    int link_len = num_places(finfo.links);
    if (link_len > info->max_link) info->max_link = link_len;

    info->total_len += name_len + 2;

    (*files)[*size] = finfo;
    (*size)++;
}

static bool recurse_directory(char* path) {
    DIR* d;
    struct dirent* file;
    bool first = true;

    d = get_directory(path);
    if (d == NULL) return false;
    

    int capacity = 8;
    int size = 0;
    struct FileInfo* files = malloc(sizeof(struct FileInfo) * capacity);
    struct FileListInfo info;
    memset(&info, 0, sizeof(struct FileListInfo));

    while((file = readdir(d)) != NULL) {
        if (file->d_type == DT_DIR) continue;
        if (!flags.hidden && prefix(".", file->d_name)) continue;
        if (is_dot_dir(file->d_name)) continue;
        if (first) {
            if (flags.colored == NO)
                printf("\n%s:\n", path);
            else
                printf("\n%s%s:%s\n", DIR_COLOR, path, FILE_COLOR);
            first = false;
        }
        push_file(&files, &info, &size, &capacity, file->d_name, path);
    }
    
    list_files(files, size, info, path);
    free(files);

    if (!flags.more_info) printf("\n");

    closedir(d);

    d = get_directory(path);
    if (d == NULL) return false;
    
    while((file = readdir(d)) != NULL) {
        if (file->d_type != DT_DIR) continue;
        if (!flags.hidden && prefix(".", file->d_name)) continue;
        if (is_dot_dir(file->d_name)) continue;
        char buf[PATH_MAX];
        append_path(buf, path, file->d_name);
        recurse_directory(buf);
    }

    closedir(d);

    return true;
}

static bool list_directory(char* path) {
    if (flags.recurse) {
        return recurse_directory(path);
    }

    DIR* d = get_directory(path);
    if (d == NULL) return false;

    int capacity = 8;
    int size = 0;
    struct FileInfo* files = malloc(sizeof(struct FileInfo) * capacity);
    struct FileListInfo info;
    memset(&info, 0, sizeof(struct FileListInfo));
    
    struct dirent* file;
    while ((file = readdir(d)) != NULL) {
        if (!flags.hidden && prefix(".", file->d_name)) continue;
        if (flags.hide_dot && is_dot_dir(file->d_name)) continue;
        push_file(&files, &info, &size, &capacity, file->d_name, path);
    }

    if (size > 0) list_files(files, size, info, path);
    free(files);
    
    closedir(d);
    return true;
}

static bool is_dir(const char* path) {
    struct stat s;
    if (stat(path, &s) < 0) return false;
    return S_ISDIR(s.st_mode);
}

static void list_file_args(int start, int argc, char** argv) {
    int capacity = 8;
    int size = 0;
    struct FileInfo* files = malloc(sizeof(struct FileInfo) * capacity);
    struct FileListInfo info;
    memset(&info, 0, sizeof(struct FileListInfo));
    
    for (int i = start; i < argc; i++) {
        if (is_dir(argv[i])) continue;
        push_file((struct FileInfo**) &files, &info, &size, &capacity, argv[i], ".");
    }
    
    if (size > 0) list_files(files, size, info, ".");

    free(files);
}

static void help(void) {
    printf("Usage: ls [FILE]...\n\n");
    printf("List directory contents\n\n");
    printf("\t-1\tOne column output\n");
    printf("\t-l\tLong format\n");
    printf("\t-a\tInclude names starting with .\n");
    printf("\t-A\tLike -a but without . and ..\n");
    printf("\t-R\tRecurse\n");
}

static int short_arg(char c, char* next) {
    UNUSED(next);
    switch (c) {
        case 'R':
            flags.recurse = true;
            break;
        case '1':
            flags.one_column = true;
            break;
        case 'A':
            flags.hide_dot = true;
            flags.hidden = true;
            break;
        case 'a':
            flags.hidden = true;
            break;
        case 'l':
            flags.more_info = true;
            break;
        default:
            error("error: unkown option -%c", c);
    }
    return ARG_UNUSED;
}

static int long_arg(char* cur, char* next) {
    UNUSED(next);
    if (prefix("--color=", cur)) {
        char* arg = cur + 8;
        if (streql("yes", arg) || streql("always", arg)) {
            flags.colored = YES;
        } else if (streql("auto", arg)) {
            flags.colored = AUTO;
        } else if (streql("no", arg) || streql("never", arg)) {
            flags.colored = NO;
        } else {
            error("error: invalid color options: %s", arg);
        }
    } else {
        return ARG_IGNORE;
    }
    return ARG_UNUSED;
}

COMMAND(ls) {

    flags.hidden = false;
    flags.more_info = false;
    flags.hide_dot = false;
    flags.one_column = false;
    flags.recurse = false;
    flags.colored = AUTO;

    int start = parse_args(argc, argv, help, short_arg, long_arg);

    if (argc - start == 0) {
        list_directory(".");
        return EXIT_SUCCESS;
    }

    list_file_args(start, argc, argv); 

    bool titled = argc - start > 1;
    for (int i = start; i < argc; i++) {
        if (!is_dir(argv[i])) continue;
        if (titled && !flags.recurse) {
            if (flags.colored != NO) 
                printf("\n%s%s:%s\n", DIR_COLOR, argv[i], FILE_COLOR);
            else
                printf("\n%s:\n", argv[i]);
        }
        if (list_directory(argv[i]) && i + 1 != argc)
            if (titled && !flags.recurse) printf("\n");
    }

    return EXIT_SUCCESS;
}