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

#include <dirent.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <errno.h>
#include <unistd.h>

static struct {
    bool recurse;
    bool preserve;
    bool sym_link;
    bool hard_link;
    bool verbose;
} flags;

static void help(void) {
    printf("Usage: cp [-rplsv] SOURCE... DEST\n\n");
    printf("Copy SOURCEs to DEST\n\n");
    printf("\t-R,-r\tRecurse\n");
    printf("\t-p\tPreserve file attributes if possible\n");
    printf("\t-l,-s\tCreate (sym)links\n");
    printf("\t-v\tVerbose\n");
}

static int short_arg(char c, char* next) {
    UNUSED(next);
    switch (c) {
        case 'R':
        case 'r':
            flags.recurse = true;
            break;
        case 'p':
            flags.preserve = true;
            break;
        case 'l':
            flags.hard_link = true;
            flags.sym_link = false;
            break;
        case 's':
            flags.sym_link = true;
            flags.hard_link = false;
            break;
        case 'v':
            flags.verbose = true;
            break;
        default:
            return ARG_INVALID;
    }
    return ARG_UNUSED;
}

static bool copy_file(char* from, char* to) {
    #define BS 1024
    
    FILE *from_f, *to_f;
    char buf[BS];
    int read;

    from_f = get_file_s(from, "r");
    if (from_f == NULL) { return false; }

    to_f = get_file_s(to, "w");
    if (to_f == NULL) { fclose(from_f); return false; }


    while ((read = fread(buf, 1, BS, from_f)) > 0) {
        fwrite(buf, 1, read, to_f);
    }

    if (flags.verbose) {
        output("copied '%s'", from);
    }

    return true;
}

static bool symlink_file(char* from, char* to) {
    if (symlink(from, to) < 0) {
        error_s("failed to symlink '%s'", from);
        return false;
    } else if (flags.verbose) {
        output("symlinked '%s'", from);
    }
    return true;
}

static bool hardlink_file(char* from, char* to) {
    if (link(from, to) < 0) {
        error_s("failed to hardlink '%s'", from);
        return false;
    } else if (flags.verbose) {
        output("hardlinked '%s'", from);
    }
    return true;
}

static void run_copy(struct stat* s) {

    char* from = get_path_buffer();
    char* to = get_path_buffer_2();

    bool result;
    if (flags.sym_link) {
        result = symlink_file(from, to);
    } else if (flags.hard_link) {
        result = hardlink_file(from, to);
    } else {
        result = copy_file(from, to);
    }

    if (!result) return;
    if (!flags.preserve) return;

    if (chmod(to, s->st_mode) < 0) {
        error_s("cannot chmod '%s'", to);
        return;
    }

    if (chown(to, s->st_uid, s->st_gid) < 0) {
        error_s("cannot chown '%s'", to);
        return;
    }
}

static void cp_file(char* path);
    
static void cp_directory(struct stat* s) {
    
    DIR* d;
    struct dirent* file;

    if (!flags.recurse) {
        error_s("-r not specified; omitting directory '%s'", get_path_buffer());
        return;
    }

    if (mkdir(get_path_buffer_2(), s->st_mode) < 0 && errno != EEXIST) {
        error_s("cannot create directory '%s'", get_path_buffer_2());
        return;
    }

    d = opendir(get_path_buffer());

    if (d == NULL) {
        error_s("cannot open directory '%s'", get_path_buffer());
        return;
    }

    while ((file = readdir(d)) != NULL) {
        if (is_dot_dir(file->d_name)) continue;
        cp_file(file->d_name);
    }
}

static char* get_file_name(char* path) {
    int last = 0;
    int i = 0;
    
    if (path[0] == '\0') return path;
    
    while (true) {
        if (path[i+1] == '\0') break;
        if (path[i] == '/') {
            last = i;
        }
        i++;
    }

    if (last == 0) return path;
    else return path + last + 1;
}

static void cp_file(char* path) {
    
    int save = push_path_buffer(path);
    int save2 = push_path_buffer_2(get_file_name(path));
    
    struct stat s;
    if (lstat(get_path_buffer(), &s) < 0) {
        pop_path_buffer(save);
        error_s("cannot stat '%s'", get_path_buffer());
        return;
    }

    if (S_ISDIR(s.st_mode)) {
        cp_directory(&s);
    } else {
        run_copy(&s);
    }
    
    pop_path_buffer(save);
    pop_path_buffer_2(save2);
}

COMMAND(cp_main) {

    int start, i;
    struct stat s;

    flags.hard_link = false;
    flags.sym_link = false;
    flags.preserve = false;
    flags.recurse = false;
    flags.verbose = false;

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

    if (argc - start < 2) {
        global_help(help);
    }

    /* only when 2 args and first is a file, the 2nd will be a file */
    if (argc - start == 2) {
        struct stat s;
        if (lstat(argv[start], &s) < 0) {
            error("cannot stat '%s'", argv[start]);
        }
        push_path_buffer(argv[argc-2]);
        push_path_buffer_2(argv[argc-1]);
        if (!S_ISDIR(s.st_mode)) {
            run_copy(&s);
        } else {
            cp_directory(&s);
        }
        return EXIT_SUCCESS;
    }
 
    /* push directory */
    push_path_buffer_2(argv[argc-1]);

    if (lstat(get_path_buffer_2(), &s) < 0) {
        error("target: '%s'", get_path_buffer_2());
    }

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

    return EXIT_SUCCESS;
}