// Copyright (C) 2004-2024 Artifex Software, Inc.

//

// This file is part of MuPDF.

//

// MuPDF is free software: you can redistribute it and/or modify it under the

// terms of the GNU Affero General Public License as published by the Free

// Software Foundation, either version 3 of the License, or (at your option)

// any later version.

//

// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY

// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more

// details.

//

// You should have received a copy of the GNU Affero General Public License

// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>

//

// Alternative licensing terms are available from the licensor.

// For commercial licensing, see <https://www.artifex.com/> or contact

// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,

// CA 94129, USA, for further information.

#include "mupdf/fitz.h"

#include "html-imp.h"

#include <string.h>

#include <math.h>

#include <zlib.h> /* for crc32 */

enum { T, R, B, L };

typedef struct epub_chapter epub_chapter;

typedef struct epub_page epub_page;

typedef struct

{

  int max_chapters;

  int num_chapters;

  float layout_w;

  float layout_h;

  float layout_em;

  uint32_t css_sum;

  int use_doc_css;

  int *pages_in_chapter;

} epub_accelerator;

typedef struct

{

  fz_document super;

  fz_archive *zip;

  fz_html_font_set *set;

  int count;

  epub_chapter *spine;

  fz_outline *outline;

  char *dc_title, *dc_creator;

  float layout_w, layout_h, layout_em;

  epub_accelerator *accel;

  uint32_t css_sum;

  /* A common pattern of use is for us to open a document,

   * load a page, draw it, drop it, load the next page,

   * draw it, drop it etc. This means that the HTML for

   * a chapter might get thrown away between the drop and

   * the the next load (if the chapter is large, and the

   * store size is low). Accordingly, we store a handle

   * to the most recently used html block here, thus

   * ensuring that the stored copy won't be evicted. */

  fz_html *most_recent_html;

} epub_document;

struct epub_chapter

{

  epub_document *doc;

  char *path;

  int number;

  epub_chapter *next;

};

struct epub_page

{

  fz_page super;

  epub_chapter *ch;

  int number;

  fz_html *html;

};

static uint32_t

user_css_sum(fz_context *ctx)

{

  uint32_t sum = 0;

  const char *css = fz_user_css(ctx);

  sum = crc32(0, NULL, 0);

  if (css)

    sum = crc32(sum, (Byte*)css, (int)strlen(css));

  return sum;

}

static int dummy = 1;

struct encrypted {

  fz_archive super;

  fz_archive *chain;

  fz_tree *info;

};

static int has_encrypted_entry(fz_context *ctx, fz_archive *arch_, const char *name)

{

  struct encrypted *arch = (struct encrypted *)arch_;

  return fz_has_archive_entry(ctx, arch->chain, name);

}

static fz_stream *open_encrypted_entry(fz_context *ctx, fz_archive *arch_, const char *name)

{

  struct encrypted *arch = (struct encrypted *)arch_;

  if (fz_tree_lookup(ctx, arch->info, name))

    return NULL;

  return fz_open_archive_entry(ctx, arch->chain, name);

}

static fz_buffer *read_encrypted_entry(fz_context *ctx, fz_archive *arch_, const char *name)

{

  struct encrypted *arch = (struct encrypted *)arch_;

  if (fz_tree_lookup(ctx, arch->info, name))

    return NULL;

  return fz_read_archive_entry(ctx, arch->chain, name);

}

static void drop_encrypted_archive(fz_context *ctx, fz_archive *arch_)

{

  struct encrypted *arch = (struct encrypted *)arch_;

  fz_drop_tree(ctx, arch->info, NULL);

  fz_drop_archive(ctx, arch->chain);

}

static fz_archive *new_encrypted_archive(fz_context *ctx, fz_archive *chain, fz_tree *info)

{

  struct encrypted *arch;

  arch = fz_new_derived_archive(ctx, NULL, struct encrypted);

  arch->super.format = "encrypted";

  arch->super.has_entry = has_encrypted_entry;

  arch->super.read_entry = read_encrypted_entry;

  arch->super.open_entry = open_encrypted_entry;

  arch->super.drop_archive = drop_encrypted_archive;

  arch->chain = chain;

  arch->info = info;

  return &arch->super;

}

static void

epub_parse_encryption(fz_context *ctx, epub_document *doc, fz_xml *root)

{

  fz_tree *info = NULL;

  fz_xml *edata;

  for (edata = fz_xml_find_down(root, "EncryptedData"); edata; edata = fz_xml_find_next(edata, "EncryptedData"))

  {

    fz_xml *cdata = fz_xml_find_down(edata, "CipherData");

    fz_xml *cref = fz_xml_find_down(cdata, "CipherReference");

    char *uri = fz_xml_att(cref, "URI");

    if (uri)

    {

      // TODO: Support reading EncryptedKey and EncryptionMethod to decrypt content.

      info = fz_tree_insert(ctx, info, uri, &dummy);

    }

  }

  if (info)

  {

    doc->zip = new_encrypted_archive(ctx, doc->zip, info);

  }

}

static fz_html *epub_get_laid_out_html(fz_context *ctx, epub_document *doc, epub_chapter *ch);

static int count_laid_out_pages(fz_html *html)

{

  if (html->tree.root->s.layout.b > 0)

    return ceilf(html->tree.root->s.layout.b / html->page_h);

  return 1;

}

static void

invalidate_accelerator(fz_context *ctx, epub_accelerator *acc)

{

  int i;

  for (i = 0; i < acc->max_chapters; i++)

    acc->pages_in_chapter[i] = -1;

}

static int count_chapter_pages(fz_context *ctx, epub_document *doc, epub_chapter *ch)

{

  epub_accelerator *acc = doc->accel;

  int use_doc_css = fz_use_document_css(ctx);

  if (use_doc_css != acc->use_doc_css || doc->css_sum != acc->css_sum)

  {

    acc->use_doc_css = use_doc_css;

    acc->css_sum = doc->css_sum;

    invalidate_accelerator(ctx, acc);

  }

  if (ch->number < acc->num_chapters && acc->pages_in_chapter[ch->number] != -1)

    return acc->pages_in_chapter[ch->number];

  fz_drop_html(ctx, epub_get_laid_out_html(ctx, doc, ch));

  return acc->pages_in_chapter[ch->number];

}

static fz_link_dest

epub_resolve_link(fz_context *ctx, fz_document *doc_, const char *dest)

{

  epub_document *doc = (epub_document*)doc_;

  epub_chapter *ch;

  int i;

  const char *s = strchr(dest, '#');

  size_t n = s ? (size_t)(s - dest) : strlen(dest);

  if (s && s[1] == 0)

    s = NULL;

  for (i = 0, ch = doc->spine; ch; ++i, ch = ch->next)

  {

    if (!strncmp(ch->path, dest, n) && ch->path[n] == 0)

    {

      if (s)

      {

        float y;

        fz_html *html = epub_get_laid_out_html(ctx, doc, ch);

        int ph = html->page_h;

        /* Search for a matching fragment */

        y = fz_find_html_target(ctx, html, s+1);

        fz_drop_html(ctx, html);

        if (y >= 0)

        {

          int page = y / ph;

          return fz_make_link_dest_xyz(i, page, 0, y - page * ph, 0);

        }

        return fz_make_link_dest_none();

      }

      return fz_make_link_dest_xyz(i, 0, 0, 0, 0);

    }

  }

  return fz_make_link_dest_none();

}

static void

epub_layout(fz_context *ctx, fz_document *doc_, float w, float h, float em)

{

  epub_document *doc = (epub_document*)doc_;

  uint32_t css_sum = user_css_sum(ctx);

  int use_doc_css = fz_use_document_css(ctx);

  if (doc->layout_w == w && doc->layout_h == h && doc->layout_em == em && doc->css_sum == css_sum)

    return;

  doc->layout_w = w;

  doc->layout_h = h;

  doc->layout_em = em;

  if (doc->accel == NULL)

    return;

  /* When we load the saved accelerator, doc->accel

   * can be populated with different values than doc.

   * This is really useful as doc starts out with the

   * values being 0. If we've got the right values

   * already, then don't bin the data! */

  if (doc->accel->layout_w == w &&

    doc->accel->layout_h == h &&

    doc->accel->layout_em == em &&

    doc->accel->use_doc_css == use_doc_css &&

    doc->accel->css_sum == css_sum)

    return;

  doc->accel->layout_w = w;

  doc->accel->layout_h = h;

  doc->accel->layout_em = em;

  doc->accel->use_doc_css = use_doc_css;

  doc->accel->css_sum = css_sum;

  invalidate_accelerator(ctx, doc->accel);

}

static int

epub_count_chapters(fz_context *ctx, fz_document *doc_)

{

  epub_document *doc = (epub_document*)doc_;

  epub_chapter *ch;

  int count = 0;

  for (ch = doc->spine; ch; ch = ch->next)

    ++count;

  return count;

}

static int

epub_count_pages(fz_context *ctx, fz_document *doc_, int chapter)

{

  epub_document *doc = (epub_document*)doc_;

  epub_chapter *ch;

  int i;

  for (i = 0, ch = doc->spine; ch; ++i, ch = ch->next)

  {

    if (i == chapter)

    {

      return count_chapter_pages(ctx, doc, ch);

    }

  }

  return 0;

}

#define MAGIC_ACCELERATOR 0xacce1e7a

#define MAGIC_ACCEL_EPUB  0x62755065

#define ACCEL_VERSION     0x00010001

static void epub_load_accelerator(fz_context *ctx, epub_document *doc, fz_stream *accel)

{

  int v;

  float w, h, em;

  int num_chapters;

  epub_accelerator *acc = NULL;

  uint32_t css_sum;

  int use_doc_css;

  int make_new = (accel == NULL);

  fz_var(acc);

  if (accel)

  {

    /* Try to read the accelerator data. If we fail silently give up. */

    fz_try(ctx)

    {

      v = fz_read_int32_le(ctx, accel);

      if (v != (int32_t)MAGIC_ACCELERATOR)

      {

        make_new = 1;

        break;

      }

      v = fz_read_int32_le(ctx, accel);

      if (v != MAGIC_ACCEL_EPUB)

      {

        make_new = 1;

        break;

      }

      v = fz_read_int32_le(ctx, accel);

      if (v != ACCEL_VERSION)

      {

        make_new = 1;

        break;

      }

      w = fz_read_float_le(ctx, accel);

      h = fz_read_float_le(ctx, accel);

      em = fz_read_float_le(ctx, accel);

      css_sum = fz_read_uint32_le(ctx, accel);

      use_doc_css = fz_read_int32_le(ctx, accel);

      num_chapters = fz_read_int32_le(ctx, accel);

      if (num_chapters <= 0)

      {

        make_new = 1;

        break;

      }

      acc = fz_malloc_struct(ctx, epub_accelerator);

      acc->pages_in_chapter = Memento_label(fz_malloc_array(ctx, num_chapters, int), "accel_pages_in_chapter");

      acc->max_chapters = acc->num_chapters = num_chapters;

      acc->layout_w = w;

      acc->layout_h = h;

      acc->layout_em = em;

      acc->css_sum = css_sum;

      acc->use_doc_css = use_doc_css;

      for (v = 0; v < num_chapters; v++)

        acc->pages_in_chapter[v] = fz_read_int32_le(ctx, accel);

    }

    fz_catch(ctx)

    {

      if (acc)

        fz_free(ctx, acc->pages_in_chapter);

      fz_free(ctx, acc);

      /* Swallow the error and run unaccelerated */

      fz_rethrow_if(ctx, FZ_ERROR_SYSTEM);

      fz_report_error(ctx);

      make_new = 1;

    }

  }

  /* If we aren't given an accelerator to load (or the one we're given

   * is bad) create a blank stub and we can fill it out as we go. */

  if (make_new)

  {

    acc = fz_malloc_struct(ctx, epub_accelerator);

    acc->css_sum = doc->css_sum;

    acc->use_doc_css = fz_use_document_css(ctx);

  }

  doc->accel = acc;

}

static void

accelerate_chapter(fz_context *ctx, epub_document *doc, epub_chapter *ch, fz_html *html)

{

  epub_accelerator *acc = doc->accel;

  int p = count_laid_out_pages(html);

  if (ch->number < acc->num_chapters)

  {

    if (acc->pages_in_chapter[ch->number] != p && acc->pages_in_chapter[ch->number] != -1)

    {

      fz_warn(ctx, "Invalidating stale accelerator data.");

      invalidate_accelerator(ctx, doc->accel);

    }

    acc->pages_in_chapter[ch->number] = p;

    return;

  }

  if (ch->number >= acc->max_chapters)

  {

    int n = acc->max_chapters;

    int i;

    if (n == 0)

      n = 4;

    while (n <= ch->number)

      n *= 2;

    acc->pages_in_chapter = fz_realloc_array(ctx, acc->pages_in_chapter, n, int);

    for (i = acc->max_chapters; i < n; i++)

      acc->pages_in_chapter[i] = -1;

    acc->max_chapters = n;

  }

  acc->pages_in_chapter[ch->number] = p;

  if (acc->num_chapters < ch->number+1)

    acc->num_chapters = ch->number+1;

}

static void

epub_drop_page(fz_context *ctx, fz_page *page_)

{

  epub_page *page = (epub_page *)page_;

  fz_drop_html(ctx, page->html);

}

static epub_chapter *

epub_load_chapter(fz_context *ctx, epub_document *doc, const char *path, int i)

{

  epub_chapter *ch;

  ch = fz_malloc_struct(ctx, epub_chapter);

  fz_try(ctx)

  {

    ch->path = Memento_label(fz_strdup(ctx, path), "chapter_path");

    ch->number = i;

  }

  fz_catch(ctx)

  {

    fz_free(ctx, ch);

    fz_rethrow(ctx);

  }

  return ch;

}

static fz_html *

epub_parse_chapter(fz_context *ctx, epub_document *doc, epub_chapter *ch)

{

  fz_archive *zip = doc->zip;

  fz_buffer *buf;

  char base_uri[2048];

  fz_html *html;

  /* Look for one we made earlier */

  html = fz_find_html(ctx, doc, ch->number);

  if (html)

    return html;

  fz_dirname(base_uri, ch->path, sizeof base_uri);

  buf = fz_read_archive_entry(ctx, zip, ch->path);

  fz_try(ctx)

    html = fz_parse_html(ctx, doc->set, zip, base_uri, buf, fz_user_css(ctx), 1, 1, 0);

  fz_always(ctx)

    fz_drop_buffer(ctx, buf);

  fz_catch(ctx)

    fz_rethrow(ctx);

  return fz_store_html(ctx, html, doc, ch->number);

}

static fz_html *

epub_get_laid_out_html(fz_context *ctx, epub_document *doc, epub_chapter *ch)

{

  fz_html *html = epub_parse_chapter(ctx, doc, ch);

  fz_try(ctx)

  {

    fz_layout_html(ctx, html, doc->layout_w, doc->layout_h, doc->layout_em);

    accelerate_chapter(ctx, doc, ch, html);

  }

  fz_catch(ctx)

  {

    fz_drop_html(ctx, html);

    fz_rethrow(ctx);

  }

  fz_drop_html(ctx, doc->most_recent_html);

  doc->most_recent_html = fz_keep_html(ctx, html);

  return html;

}

static fz_rect

epub_bound_page(fz_context *ctx, fz_page *page_, fz_box_type box)

{

  epub_document *doc = (epub_document*)page_->doc;

  epub_page *page = (epub_page*)page_;

  epub_chapter *ch = page->ch;

  fz_rect bbox;

  fz_html *html = epub_get_laid_out_html(ctx, doc, ch);

  bbox.x0 = 0;

  bbox.y0 = 0;

  bbox.x1 = html->page_w + html->page_margin[L] + html->page_margin[R];

  bbox.y1 = html->page_h + html->page_margin[T] + html->page_margin[B];

  fz_drop_html(ctx, html);

  return bbox;

}

static void

epub_run_page(fz_context *ctx, fz_page *page_, fz_device *dev, fz_matrix ctm, fz_cookie *cookie)

{

  epub_page *page = (epub_page*)page_;

  fz_draw_html(ctx, dev, ctm, page->html, page->number);

}

static fz_link *

epub_load_links(fz_context *ctx, fz_page *page_)

{

  epub_page *page = (epub_page*)page_;

  epub_chapter *ch = page->ch;

  return fz_load_html_links(ctx, page->html, page->number, ch->path);

}

static fz_bookmark

epub_make_bookmark(fz_context *ctx, fz_document *doc_, fz_location loc)

{

  epub_document *doc = (epub_document*)doc_;

  epub_chapter *ch;

  int i;

  for (i = 0, ch = doc->spine; ch; ++i, ch = ch->next)

  {

    if (i == loc.chapter)

    {

      fz_html *html = epub_get_laid_out_html(ctx, doc, ch);

      fz_bookmark mark = fz_make_html_bookmark(ctx, html, loc.page);

      fz_drop_html(ctx, html);

      return mark;

    }

  }

  return 0;

}

static fz_location

epub_lookup_bookmark(fz_context *ctx, fz_document *doc_, fz_bookmark mark)

{

  epub_document *doc = (epub_document*)doc_;

  epub_chapter *ch;

  int i;

  for (i = 0, ch = doc->spine; ch; ++i, ch = ch->next)

  {

    fz_html *html = epub_get_laid_out_html(ctx, doc, ch);

    int p = fz_lookup_html_bookmark(ctx, html, mark);

    fz_drop_html(ctx, html);

    if (p != -1)

      return fz_make_location(i, p);

  }

  return fz_make_location(-1, -1);

}

static fz_page *

epub_load_page(fz_context *ctx, fz_document *doc_, int chapter, int number)

{

  epub_document *doc = (epub_document*)doc_;

  epub_chapter *ch;

  int i;

  for (i = 0, ch = doc->spine; ch; ++i, ch = ch->next)

  {

    if (i == chapter)

    {

      epub_page *page = fz_new_derived_page(ctx, epub_page, doc_);

      page->super.bound_page = epub_bound_page;

      page->super.run_page_contents = epub_run_page;

      page->super.load_links = epub_load_links;

      page->super.drop_page = epub_drop_page;

      page->ch = ch;

      page->number = number;

      page->html = epub_get_laid_out_html(ctx, doc, ch);

      return (fz_page*)page;

    }

  }

  return NULL;

}

static void

epub_page_label(fz_context *ctx, fz_document *doc_, int chapter, int number, char *buf, size_t size)

{

  fz_snprintf(buf, size, "ch. %d, p. %d", chapter+1, number+1);

}

static void

epub_drop_accelerator(fz_context *ctx, epub_accelerator *acc)

{

  if (acc == NULL)

    return;

  fz_free(ctx, acc->pages_in_chapter);

  fz_free(ctx, acc);

}

static void

epub_drop_document(fz_context *ctx, fz_document *doc_)

{

  epub_document *doc = (epub_document*)doc_;

  epub_chapter *ch, *next;

  ch = doc->spine;

  while (ch)

  {

    next = ch->next;

    fz_free(ctx, ch->path);

    fz_free(ctx, ch);

    ch = next;

  }

  epub_drop_accelerator(ctx, doc->accel);

  fz_drop_archive(ctx, doc->zip);

  fz_drop_html_font_set(ctx, doc->set);

  fz_drop_outline(ctx, doc->outline);

  fz_free(ctx, doc->dc_title);

  fz_free(ctx, doc->dc_creator);

  fz_drop_html(ctx, doc->most_recent_html);

  fz_purge_stored_html(ctx, doc);

}

static const char *

rel_path_from_idref(fz_xml *manifest, const char *idref)

{

  fz_xml *item;

  if (!idref)

    return NULL;

  item = fz_xml_find_down(manifest, "item");

  while (item)

  {

    const char *id = fz_xml_att(item, "id");

    if (id && !strcmp(id, idref))

      return fz_xml_att(item, "href");

    item = fz_xml_find_next(item, "item");

  }

  return NULL;

}

static const char *

path_from_idref(char *path, fz_xml *manifest, const char *base_uri, const char *idref, int n)

{

  const char *rel_path = rel_path_from_idref(manifest, idref);

  if (!rel_path)

  {

    path[0] = 0;

    return NULL;

  }

  fz_strlcpy(path, base_uri, n);

  fz_strlcat(path, "/", n);

  fz_strlcat(path, rel_path, n);

  return fz_cleanname(fz_urldecode(path));

}

static fz_outline *

epub_parse_ncx_imp(fz_context *ctx, epub_document *doc, fz_xml *node, char *base_uri)

{

  char path[2048];

  fz_outline *outline, *head, **tailp;

  head = NULL;

  tailp = &head;

  node = fz_xml_find_down(node, "navPoint");

  while (node)

  {

    char *text = fz_xml_text(fz_xml_down(fz_xml_find_down(fz_xml_find_down(node, "navLabel"), "text")));

    char *content = fz_xml_att(fz_xml_find_down(node, "content"), "src");

    if (text && content)

    {

      fz_strlcpy(path, base_uri, sizeof path);

      fz_strlcat(path, "/", sizeof path);

      fz_strlcat(path, content, sizeof path);

      fz_urldecode(path);

      fz_cleanname(path);

      fz_try(ctx)

      {

        *tailp = outline = fz_new_outline(ctx);

        tailp = &(*tailp)->next;

        outline->title = Memento_label(fz_strdup(ctx, text), "outline_title");

        outline->uri = Memento_label(fz_strdup(ctx, path), "outline_uri");

        outline->page = fz_make_location(-1, -1);

        outline->down = epub_parse_ncx_imp(ctx, doc, node, base_uri);

        outline->is_open = 1;

      }

      fz_catch(ctx)

      {

        fz_drop_outline(ctx, head);

        fz_rethrow(ctx);

      }

    }

    node = fz_xml_find_next(node, "navPoint");

  }

  return head;

}

static void

epub_parse_ncx(fz_context *ctx, epub_document *doc, const char *path)

{

  fz_archive *zip = doc->zip;

  fz_buffer *buf = NULL;

  fz_xml_doc *ncx = NULL;

  char base_uri[2048];

  fz_var(buf);

  fz_var(ncx);

  fz_try(ctx)

  {

    fz_dirname(base_uri, path, sizeof base_uri);

    buf = fz_read_archive_entry(ctx, zip, path);

    ncx = fz_parse_xml(ctx, buf, 0);

    doc->outline = epub_parse_ncx_imp(ctx, doc, fz_xml_find_down(fz_xml_root(ncx), "navMap"), base_uri);

  }

  fz_always(ctx)

  {

    fz_drop_buffer(ctx, buf);

    fz_drop_xml(ctx, ncx);

  }

  fz_catch(ctx)

    fz_rethrow(ctx);

}

static char *

find_metadata(fz_context *ctx, fz_xml *metadata, char *key)

{

  char *text = fz_xml_text(fz_xml_down(fz_xml_find_down(metadata, key)));

  if (text)

    return fz_strdup(ctx, text);

  return NULL;

}

static fz_buffer *

read_container_and_prefix(fz_context *ctx, fz_archive *zip, char *prefix, size_t prefix_len)

{

  int n = fz_count_archive_entries(ctx, zip);

  int i;

  prefix[0] = 0;

  /* First off, look for the container.xml at the top level. */

  for (i = 0; i < n; i++)

  {

    const char *p = fz_list_archive_entry(ctx, zip, i);

    if (!strcmp(p, "META-INF/container.xml"))

      return fz_read_archive_entry(ctx, zip, "META-INF/container.xml");

  }

  /* If that failed, look for the first such file in a subdirectory. */

  for (i = 0; i < n; i++)

  {

    const char *p = fz_list_archive_entry(ctx, zip, i);

    size_t z = strlen(p);

    size_t z0 = sizeof("META-INF/container.xml")-1;

    if (z < z0)

      continue;

    if (!strcmp(p + z - z0, "META-INF/container.xml"))

    {

      if (z - z0 >= prefix_len)

      {

        fz_warn(ctx, "Ignoring %s as path too long.", p);

        continue;

      }

      memcpy(prefix, p, z-z0);

      prefix[z-z0] = 0;

      return fz_read_archive_entry(ctx, zip, p);

    }

  }

  return fz_read_archive_entry(ctx, zip, "META-INF/container.xml");

}

static void

epub_parse_header(fz_context *ctx, epub_document *doc)

{

  fz_archive *zip = doc->zip;

  fz_buffer *buf = NULL;

  fz_xml_doc *encryption_xml = NULL;

  fz_xml_doc *container_xml = NULL;

  fz_xml_doc *content_opf = NULL;

  fz_xml *container, *rootfiles, *rootfile;

  fz_xml *package, *manifest, *spine, *itemref, *metadata;

  char base_uri[2048];

  const char *full_path;

  const char *version;

  char ncx[2048], s[2048];

  char *prefixed_full_path = NULL;

  size_t prefix_len;

  epub_chapter **tailp;

  int i;

  fz_var(buf);

  fz_var(encryption_xml);

  fz_var(container_xml);

  fz_var(content_opf);

  fz_var(prefixed_full_path);

  fz_try(ctx)

  {

    /* parse META-INF/encryption.xml to figure out which entries are encrypted */

    /* parse META-INF/container.xml to find OPF */

    /* Reuse base_uri to read the prefix. */

    buf = read_container_and_prefix(ctx, zip, base_uri, sizeof(base_uri));

    container_xml = fz_parse_xml(ctx, buf, 0);

    fz_drop_buffer(ctx, buf);

    buf = NULL;

    /* Some epub files can be prefixed by a directory name. This (normally

     * empty!) will be in base_uri. */

    prefix_len = strlen(base_uri);

    {

      /* Further abuse base_uri to hold a temporary name. */

      const size_t z0 = sizeof("META-INF/encryption.xml")-1;

      if (sizeof(base_uri) <= prefix_len + z0)

        fz_throw(ctx, FZ_ERROR_FORMAT, "Prefix too long in epub");

      strcpy(base_uri + prefix_len, "META-INF/encryption.xml");

      if (fz_has_archive_entry(ctx, zip, base_uri))

      {

        fz_warn(ctx, "EPUB may be locked by DRM");

        buf = fz_read_archive_entry(ctx, zip, base_uri);

        encryption_xml = fz_parse_xml(ctx, buf, 0);

        fz_drop_buffer(ctx, buf);

        buf = NULL;

        epub_parse_encryption(ctx, doc, fz_xml_find(fz_xml_root(encryption_xml), "encryption"));

        zip = doc->zip;

      }

    }

    container = fz_xml_find(fz_xml_root(container_xml), "container");

    rootfiles = fz_xml_find_down(container, "rootfiles");

    rootfile = fz_xml_find_down(rootfiles, "rootfile");

    full_path = fz_xml_att(rootfile, "full-path");

    if (!full_path)

      fz_throw(ctx, FZ_ERROR_FORMAT, "cannot find root file in EPUB");

    fz_dirname(base_uri+prefix_len, full_path, sizeof(base_uri) - prefix_len);

    prefixed_full_path = fz_malloc(ctx, strlen(full_path) + prefix_len + 1);

    memcpy(prefixed_full_path, base_uri, prefix_len);

    strcpy(prefixed_full_path + prefix_len, full_path);

    /* parse OPF to find NCX and spine */

    buf = fz_read_archive_entry(ctx, zip, prefixed_full_path);

    content_opf = fz_parse_xml(ctx, buf, 0);

    fz_drop_buffer(ctx, buf);

    buf = NULL;

    package = fz_xml_find(fz_xml_root(content_opf), "package");

    version = fz_xml_att(package, "version");

    if (!version || strcmp(version, "2.0"))

      fz_warn(ctx, "unknown epub version: %s", version ? version : "<none>");

    metadata = fz_xml_find_down(package, "metadata");

    if (metadata)

    {

      doc->dc_title = Memento_label(find_metadata(ctx, metadata, "title"), "epub_title");

      doc->dc_creator = Memento_label(find_metadata(ctx, metadata, "creator"), "epub_creator");

    }

    manifest = fz_xml_find_down(package, "manifest");

    spine = fz_xml_find_down(package, "spine");