/*
 * Copyright (c) 2006 Rene Scharfe
 */
#include <time.h>
#include "cache.h"
#include "commit.h"
#include "blob.h"
#include "tree.h"
#include "quote.h"
#include "builtin.h"

static const char zip_tree_usage[] =
"git-zip-tree [-0|...|-9] <tree-ish> [ <base> ]";

static int zip_date;
static int zip_time;

static unsigned char *zip_dir;
static unsigned int zip_dir_size;

static unsigned int zip_offset;
static unsigned int zip_dir_offset;
static unsigned int zip_dir_entries;

#define ZIP_DIRECTORY_MIN_SIZE  (1024 * 1024)

struct zip_local_header {
        unsigned char magic[4];
        unsigned char version[2];
        unsigned char flags[2];
        unsigned char compression_method[2];
        unsigned char mtime[2];
        unsigned char mdate[2];
        unsigned char crc32[4];
        unsigned char compressed_size[4];
        unsigned char size[4];
        unsigned char filename_length[2];
        unsigned char extra_length[2];
};

struct zip_dir_header {
        unsigned char magic[4];
        unsigned char creator_version[2];
        unsigned char version[2];
        unsigned char flags[2];
        unsigned char compression_method[2];
        unsigned char mtime[2];
        unsigned char mdate[2];
        unsigned char crc32[4];
        unsigned char compressed_size[4];
        unsigned char size[4];
        unsigned char filename_length[2];
        unsigned char extra_length[2];
        unsigned char comment_length[2];
        unsigned char disk[2];
        unsigned char attr1[2];
        unsigned char attr2[4];
        unsigned char offset[4];
};

struct zip_dir_trailer {
        unsigned char magic[4];
        unsigned char disk[2];
        unsigned char directory_start_disk[2];
        unsigned char entries_on_this_disk[2];
        unsigned char entries[2];
        unsigned char size[4];
        unsigned char offset[4];
        unsigned char comment_length[2];
};

static void copy_le16(unsigned char *dest, unsigned int n)
{
        dest[0] = 0xff & n;
        dest[1] = 0xff & (n >> 010);
}

static void copy_le32(unsigned char *dest, unsigned int n)
{
        dest[0] = 0xff & n;
        dest[1] = 0xff & (n >> 010);
        dest[2] = 0xff & (n >> 020);
        dest[3] = 0xff & (n >> 030);
}

static void *zlib_deflate(void *data, unsigned long size,
                          unsigned long *compressed_size)
{
        z_stream stream;
        unsigned long maxsize;
        void *buffer;
        int result;

        memset(&stream, 0, sizeof(stream));
        deflateInit(&stream, zlib_compression_level);
        maxsize = deflateBound(&stream, size);
        buffer = xmalloc(maxsize);

        stream.next_in = data;
        stream.avail_in = size;
        stream.next_out = buffer;
        stream.avail_out = maxsize;

        do {
                result = deflate(&stream, Z_FINISH);
        } while (result == Z_OK);

        if (result != Z_STREAM_END) {
                free(buffer);
                return NULL;
        }

        deflateEnd(&stream);
        *compressed_size = stream.total_out;

        return buffer;
}

static char *construct_path(const char *base, int baselen,
                            const char *filename, int isdir, int *pathlen)
{
        int filenamelen = strlen(filename);
        int len = baselen + filenamelen;
        char *path, *p;

        if (isdir)
                len++;
        p = path = xmalloc(len + 1);

        memcpy(p, base, baselen);
        p += baselen;
        memcpy(p, filename, filenamelen);
        p += filenamelen;
        if (isdir)
                *p++ = '/';
        *p = '\0';

        *pathlen = len;

        return path;
}

static int write_zip_entry(const unsigned char *sha1,
                           const char *base, int baselen,
                           const char *filename, unsigned mode, int stage)
{
        struct zip_local_header header;
        struct zip_dir_header dirent;
        unsigned long compressed_size;
        unsigned long uncompressed_size;
        unsigned long crc;
        unsigned long direntsize;
        unsigned long size;
        int method;
        int result = -1;
        int pathlen;
        unsigned char *out;
        char *path;
        char type[20];
        void *buffer = NULL;
        void *deflated = NULL;

        crc = crc32(0, Z_NULL, 0);

        path = construct_path(base, baselen, filename, S_ISDIR(mode), &pathlen);
        if (pathlen > 0xffff) {
                error("path too long (%d chars, SHA1: %s): %s", pathlen,
                      sha1_to_hex(sha1), path);
                goto out;
        }

        if (S_ISDIR(mode)) {
                method = 0;
                result = READ_TREE_RECURSIVE;
                out = NULL;
                uncompressed_size = 0;
                compressed_size = 0;
        } else if (S_ISREG(mode)) {
                method = zlib_compression_level == 0 ? 0 : 8;
                result = 0;
                buffer = read_sha1_file(sha1, type, &size);
                if (!buffer)
                        die("cannot read %s", sha1_to_hex(sha1));
                crc = crc32(crc, buffer, size);
                out = buffer;
                uncompressed_size = size;
                compressed_size = size;
        } else {
                error("unsupported file mode: 0%o (SHA1: %s)", mode,
                      sha1_to_hex(sha1));
                goto out;
        }

        if (method == 8) {
                deflated = zlib_deflate(buffer, size, &compressed_size);
                if (deflated && compressed_size - 6 < size) {
                        /* ZLIB --> raw compressed data (see RFC 1950) */
                        /* CMF and FLG ... */
                        out = (unsigned char *)deflated + 2;
                        compressed_size -= 6;   /* ... and ADLER32 */
                } else {
                        method = 0;
                        compressed_size = size;
                }
        }

        /* make sure we have enough free space in the dictionary */
        direntsize = sizeof(struct zip_dir_header) + pathlen;
        while (zip_dir_size < zip_dir_offset + direntsize) {
                zip_dir_size += ZIP_DIRECTORY_MIN_SIZE;
                zip_dir = xrealloc(zip_dir, zip_dir_size);
        }

        copy_le32(dirent.magic, 0x02014b50);
        copy_le16(dirent.creator_version, 0);
        copy_le16(dirent.version, 20);
        copy_le16(dirent.flags, 0);
        copy_le16(dirent.compression_method, method);
        copy_le16(dirent.mtime, zip_time);
        copy_le16(dirent.mdate, zip_date);
        copy_le32(dirent.crc32, crc);
        copy_le32(dirent.compressed_size, compressed_size);
        copy_le32(dirent.size, uncompressed_size);
        copy_le16(dirent.filename_length, pathlen);
        copy_le16(dirent.extra_length, 0);
        copy_le16(dirent.comment_length, 0);
        copy_le16(dirent.disk, 0);
        copy_le16(dirent.attr1, 0);
        copy_le32(dirent.attr2, 0);
        copy_le32(dirent.offset, zip_offset);
        memcpy(zip_dir + zip_dir_offset, &dirent, sizeof(struct zip_dir_header));
        zip_dir_offset += sizeof(struct zip_dir_header);
        memcpy(zip_dir + zip_dir_offset, path, pathlen);
        zip_dir_offset += pathlen;
        zip_dir_entries++;

        copy_le32(header.magic, 0x04034b50);
        copy_le16(header.version, 20);
        copy_le16(header.flags, 0);
        copy_le16(header.compression_method, method);
        copy_le16(header.mtime, zip_time);
        copy_le16(header.mdate, zip_date);
        copy_le32(header.crc32, crc);
        copy_le32(header.compressed_size, compressed_size);
        copy_le32(header.size, uncompressed_size);
        copy_le16(header.filename_length, pathlen);
        copy_le16(header.extra_length, 0);
        write_or_die(1, &header, sizeof(struct zip_local_header));
        zip_offset += sizeof(struct zip_local_header);
        write_or_die(1, path, pathlen);
        zip_offset += pathlen;
        if (compressed_size > 0) {
                write_or_die(1, out, compressed_size);
                zip_offset += compressed_size;
        }

out:
        free(buffer);
        free(deflated);
        free(path);

        return result;
}

static void write_zip_trailer(const unsigned char *sha1)
{
        struct zip_dir_trailer trailer;

        copy_le32(trailer.magic, 0x06054b50);
        copy_le16(trailer.disk, 0);
        copy_le16(trailer.directory_start_disk, 0);
        copy_le16(trailer.entries_on_this_disk, zip_dir_entries);
        copy_le16(trailer.entries, zip_dir_entries);
        copy_le32(trailer.size, zip_dir_offset);
        copy_le32(trailer.offset, zip_offset);
        copy_le16(trailer.comment_length, sha1 ? 40 : 0);

        write_or_die(1, zip_dir, zip_dir_offset);
        write_or_die(1, &trailer, sizeof(struct zip_dir_trailer));
        if (sha1)
                write_or_die(1, sha1_to_hex(sha1), 40);
}

static void dos_time(time_t *time, int *dos_date, int *dos_time)
{
        struct tm *t = localtime(time);

        *dos_date = t->tm_mday + (t->tm_mon + 1) * 32 +
                    (t->tm_year + 1900 - 1980) * 512;
        *dos_time = t->tm_sec / 2 + t->tm_min * 32 + t->tm_hour * 2048;
}

int cmd_zip_tree(int argc, const char **argv, const char *prefix)
{
        unsigned char sha1[20];
        struct tree *tree;
        struct commit *commit;
        time_t archive_time;
        char *base;
        int baselen;

        git_config(git_default_config);

        if (argc > 1 && argv[1][0] == '-') {
                if (isdigit(argv[1][1]) && argv[1][2] == '\0') {
                        zlib_compression_level = argv[1][1] - '0';
                        argc--;
                        argv++;
                }
        }

        switch (argc) {
        case 3:
                base = strdup(argv[2]);
                baselen = strlen(base);
                break;
        case 2:
                base = strdup("");
                baselen = 0;
                break;
        default:
                usage(zip_tree_usage);
        }

        if (get_sha1(argv[1], sha1))
                die("Not a valid object name %s", argv[1]);

        commit = lookup_commit_reference_gently(sha1, 1);
        archive_time = commit ? commit->date : time(NULL);
        dos_time(&archive_time, &zip_date, &zip_time);

        zip_dir = xmalloc(ZIP_DIRECTORY_MIN_SIZE);
        zip_dir_size = ZIP_DIRECTORY_MIN_SIZE;

        tree = parse_tree_indirect(sha1);
        if (!tree)
                die("not a tree object");

        if (baselen > 0) {
                write_zip_entry(tree->object.sha1, "", 0, base, 040777, 0);
                base = xrealloc(base, baselen + 1);
                base[baselen] = '/';
                baselen++;
                base[baselen] = '\0';
        }
        read_tree_recursive(tree, base, baselen, 0, NULL, write_zip_entry);
        write_zip_trailer(commit ? commit->object.sha1 : NULL);

        free(zip_dir);
        free(base);

        return 0;
}