#include <sys/mman.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include <stdint.h>
#include <stdio.h>

#include "package.h"
#include "extract.h"

#define MMAPSIZE (100*1024*1024)
#define BUFSIZE (1024*1024)

int copy_file(const char *src, const char *dst, uint32_t l) {
    int sfd = -1, dfd = -1, r = -1;
    uint32_t m;
    off_t o;
    void *src_p, *dst_p;
    void *buf = NULL;

    if ((sfd = open(src, O_RDONLY)) < 0) {
        fprintf(stderr, "open(%s, O_RDONLY): %s\n", src, strerror(errno));
        goto finish;
    }

    if ((dfd = open(dst, O_RDWR|O_TRUNC|O_CREAT, 0666)) < 0) {
        fprintf(stderr, "open(%s, O_WRONLY): %s\n", dst, strerror(errno));
        goto finish;
    }

    if (ftruncate(dfd, l) < 0) {
        fprintf(stderr, "ftruncate(): %s\n", strerror(errno));
        goto finish;
    }

    o = 0;
    m = l < MMAPSIZE ? l : MMAPSIZE;

    while (l > 0) {
        if ((src_p = mmap(NULL, m, PROT_READ, MAP_SHARED, sfd, o)) == MAP_FAILED)
            break;
        
        if ((dst_p = mmap(NULL, m, PROT_READ|PROT_WRITE, MAP_SHARED, dfd, o)) == MAP_FAILED) {
            munmap(src_p, m);
            break;
        }
        
        memcpy(dst_p, src_p, m);

        munmap(src_p, m);
        munmap(dst_p, m);
        
        o += m;
        l -= m;
        m = l < MMAPSIZE ? l : MMAPSIZE;
    }

    if (l > 0) {
        fprintf(stderr, "mmap() failed: %s\n", strerror(errno));

        if (!(buf = malloc(BUFSIZE)))
            goto finish;

        for (;;) {
            ssize_t r;

            if ((m = read(sfd, buf, BUFSIZE)) < 0) {
                fprintf(stderr, "read(): %s\n", strerror(errno));
                goto finish;
            }

            if (!m)
                break;
                
            if ((r = write(dfd, buf, m)) < 0) {
                fprintf(stderr, "write(): %s\n", strerror(errno));
                goto finish;
            }
        }
    }

    
    r = 0;

finish:
    
    if (sfd >= 0)
        close(sfd);

    if (dfd >= 0)
        close(dfd);

    return r;
}

static int cb(struct package *p, const char *name, const char *path, void *u) {
    struct stat st;
    uint32_t size;

    if (stat(path, &st) < 0) {
        if (errno == ENOENT)
            size = 0;
        else {
            fprintf(stderr, "stat(%s) failed: %s\n", path, strerror(errno));
            return -1;
        }
    } else
        size = (uint32_t) st.st_size;

    if (size)
        return copy_file(path, name, size);

    return 0;
}

int extract(struct syrep_db_context *context) {
    return package_foreach(context->package, cb, NULL);
}