// file      : bpkg/manifest-serializer.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
// license   : MIT; see accompanying LICENSE file

#include <bpkg/manifest-serializer>

#include <ostream>
#include <cassert>

using namespace std;

namespace bpkg
{
  using serialization = manifest_serialization;

  void manifest_serializer::
  next (const string& n, const string& v)
  {
    switch (s_)
    {
    case start:
      {
        if (!n.empty ())
          throw serialization (name_, "format version pair expected");

        if (v.empty ())
        {
          // End of manifests.
          //
          os_.flush ();
          s_ = end;
          break;
        }

        if (v != "1")
          throw serialization (name_, "unsupported format version " + v);

        os_ << ':';

        if (v != version_)
        {
          os_ << ' ' << v;
          version_ = v;
        }

        os_ << endl;
        s_ = body;
        break;
      }
    case body:
      {
        if (n.empty ())
        {
          if (!v.empty ())
            throw serialization (name_, "non-empty value in end pair");

          s_ = start;
          break;
        }

        check_name (n);

        os_ << n << ':';

        if (!v.empty ())
        {
          os_ << ' ';

          // Use the multi-line mode in any of the following cases:
          //
          // - name is too long (say longer than 37 (78/2 - 2) characters;
          //   we cannot start on the next line since that would start the
          //   multi-line mode)
          // - value contains newlines
          // - value contains leading/trailing whitespaces
          //
          if (n.size () > 37 ||
              v.find ('\n') != string::npos ||
              v.front () == ' ' || v.front () == '\t' ||
              v.back () == ' ' || v.back () == '\t')
          {
            os_ << "\\" << endl; // Multi-line mode introductor.

            // Chunk the value into fragments separated by newlines.
            //
            for (size_t i (0), p (v.find ('\n')); ; p = v.find ('\n', i))
            {
              if (p == string::npos)
              {
                // Last chunk.
                //
                write_value (0, v.c_str () + i, v.size () - i);
                break;
              }

              write_value (0, v.c_str () + i, p - i);
              os_ << endl;
              i = p + 1;
            }

            os_ << endl << "\\"; // Multi-line mode terminator.
          }
          else
            write_value (n.size () + 2, v.c_str (), v.size ());
        }

        os_ << endl;
        break;
      }
    case end:
      {
        throw serialization (name_, "serialization after eos");
      }
    }
  }

  void manifest_serializer::
  comment (const string& t)
  {
    if (s_ == end)
      throw serialization (name_, "serialization after eos");

    os_ << '#';

    if (!t.empty ())
      os_ << ' ' << t;

    os_ << endl;
  }

  void manifest_serializer::
  check_name (const string& n)
  {
    if (n[0] == '#')
      throw serialization (name_, "name starts with '#'");

    for (char c: n)
    {
      switch (c)
      {
      case ' ':
      case '\t':
      case '\n': throw serialization (name_, "name contains whitespace");
      case ':': throw serialization (name_, "name contains ':'");
      default: break;
      }
    }
  }

  void manifest_serializer::
  write_value (size_t cl, const char* s, size_t n)
  {
    char c ('\0');

    // The idea is to break on the 77th character (i.e., write it
    // on the next line) which means we have written 76 characters
    // on this line plus 2 for '\' and '\n', which gives us 78.
    //
    for (const char* e (s + n); s != e; s++, cl++)
    {
      c = *s;
      bool br (false); // Break the line.

      // If this is a whitespace, see if it's a good place to break the
      // line.
      //
      if (c == ' ' || c == '\t')
      {
        // Find the next whitespace (or the end) and see if it is a better
        // place.
        //
        for (const char* w (s + 1); ; w++)
        {
          if (w == e || *w == ' ' || *w == '\t')
          {
            // Is this whitespace past where we need to break? Also see
            // below the "hard" break case for why we use 78 at the end.
            //
            if (cl + static_cast<size_t> (w - s) > (w != e ? 77 : 78))
            {
              // Only break if this whitespace is close enough to
              // the end of the line.
              //
              br = (cl > 57);
            }

            break;
          }
        }
      }

      // Do we have to do a "hard" break (i.e., without a whitespace)?
      // If there is just one character left, then instead of writing
      // '\' and then the character on the next line, we might as well
      // write it on this line.
      //
      if (cl == (s + 1 != e ? 77 : 78))
        br = true;

      if (br)
      {
        os_ << '\\' << endl;
        cl = 0;
      }

      os_ << c;
    }

    // What comes next is always a newline. I the last character that
    // we have written is a backslash, escape it.
    //
    if (c == '\\')
      os_ << '\\';
  }

  // manifest_serialization
  //

  static string
  format (const string& n, const string& d)
  {
    string r;
    if (!n.empty ())
    {
      r += n;
      r += ": ";
    }
    r += "error: ";
    r += d;
    return r;
  }

  manifest_serialization::
  manifest_serialization (const string& n, const string& d)
      : runtime_error (format (n, d)), name (n), description (d)
  {
  }
}