#include "stat.h"
/* du [dir]: disk usage per entry, and a total, in 256-byte blocks.
 *
 * Blocks, not bytes, for two reasons: it is the unit df(1) and the filesystem
 * itself use, and bytes overflow - /bin alone is 52 programs x 16 KiB, which
 * wraps a 16-bit counter (it printed 32768).
 *
 * Recurses by re-opendir'ing: the kernel keeps ONE "directory being listed"
 * (wListDir), so walking into a child loses the parent's cursor - the parent
 * has to be re-opened and re-indexed on the way back up. With 32 inodes and
 * shallow trees that costs nothing. */

#define MAXDEPTH 3

static unsigned int total; /* 256-byte blocks */

static void pad(unsigned int n, unsigned char w) {
    unsigned char d = 1;
    unsigned int v = n;
    while (v >= 10) {
        v = v / 10;
        d++;
    }
    while (d++ < w) putc(' ');
    putu(n);
}

/* sum one directory, printing each entry; returns its byte total */
static unsigned int walk(char *path, unsigned char depth) {
    char name[16];
    char child[40];
    struct gstat st;
    unsigned int sum = 0;
    unsigned char i, j, k;

    for (i = 0;; i++) {
        if (opendir(path)) return sum; /* re-open: flist has one cursor */
        if (!flist(i, name)) break;
        name[15] = 0;
        j = 0;
        for (k = 0; path[k] && j < 30; k++) child[j++] = path[k];
        if (j && child[j - 1] != '/') child[j++] = '/';
        for (k = 0; name[k] && j < 38; k++) child[j++] = name[k];
        child[j] = 0;
        if (!gstat(child, &st)) continue;
        if (st.type == ST_DIR && depth < MAXDEPTH) {
            sum += walk(child, (unsigned char)(depth + 1));
        } else {
            {
                unsigned int blk = (unsigned int)((st.size + 255) / 256);
                sum += blk;
                pad(blk, 6);
            }
            putc(' ');
            puts(child);
            nl();
        }
    }
    pad(sum, 6);
    putc(' ');
    puts(path);
    nl();
    return sum;
}

void main(void) {
    char dir[32];
    char *argv[4];
    unsigned char argc = argv_parse(argv, 4);
    unsigned char i, j, have = 0;

    /* copy the argument before gstat's static request block lands on $A000 */
    for (i = 0; i < argc; i++)
        if (argv[i][0] != '-') {
            for (j = 0; argv[i][j] && j < 31; j++) dir[j] = argv[i][j];
            dir[j] = 0;
            have = 1;
            break;
        }
    if (!have) {
        dir[0] = '/';
        dir[1] = 0;
    }
    total = walk(dir, 0);
}