/*
 * Copyright (c) 2003-2012, John Wiegley.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of New Artisans LLC nor the names of its
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <system.hh>

#include "format.h"
#include "scope.h"
#include "pstream.h"

namespace ledger {

format_t::elision_style_t format_t::default_style         = TRUNCATE_TRAILING;
bool                      format_t::default_style_changed = false;

void format_t::element_t::dump(std::ostream& out) const
{
  out << "Element: ";

  switch (type) {
  case STRING: out << " STRING"; break;
  case EXPR:   out << "   EXPR"; break;
  }

  out << "  flags: 0x" << std::hex << int(flags());
  out << "  min: ";
  out << std::right;
  out.width(2);
  out << std::dec << int(min_width);
  out << "  max: ";
  out << std::right;
  out.width(2);
  out << std::dec << int(max_width);

  switch (type) {
  case STRING:
    out << "   str: '" << boost::get<string>(data) << "'" << std::endl;
    break;
  case EXPR:
    out << "  expr: "   << boost::get<expr_t>(data) << std::endl;
    break;
  }
}

namespace {
  expr_t parse_single_expression(const char *& p, bool single_expr = true)
  {
    string temp(p);
    ptristream str(const_cast<char *&>(p));
    expr_t expr;
    expr.parse(str, single_expr ? PARSE_SINGLE : PARSE_PARTIAL, temp);
    if (str.eof()) {
      expr.set_text(p);
      p += std::strlen(p);
    } else {
      assert(str.good());
      istream_pos_type pos = str.tellg();
      expr.set_text(string(p, p + long(pos)));
      p += long(pos) - 1;

      // Don't gobble up any whitespace
      const char * base = p;
      while (p >= base && std::isspace(*p))
        p--;
    }
    return expr;
  }
}

format_t::element_t * format_t::parse_elements(const string& fmt,
                                               const optional<format_t&>& tmpl)
{
  std::auto_ptr<element_t> result;

  element_t * current = NULL;

  char   buf[1024];
  char * q = buf;

  for (const char * p = fmt.c_str(); *p; p++) {
    if (*p != '%' && *p != '\\') {
      *q++ = *p;
      continue;
    }

    if (! result.get()) {
      result.reset(new element_t);
      current = result.get();
    } else {
      current->next.reset(new element_t);
      current = current->next.get();
    }

    if (q != buf) {
      current->type  = element_t::STRING;
      current->data = string(buf, q);
      q = buf;

      current->next.reset(new element_t);
      current = current->next.get();
    }

    if (*p == '\\') {
      p++;
      current->type = element_t::STRING;
      switch (*p) {
      case 'b':  current->data = string("\b");  break;
      case 'f':  current->data = string("\f");  break;
      case 'n':  current->data = string("\n");  break;
      case 'r':  current->data = string("\r");  break;
      case 't':  current->data = string("\t");  break;
      case 'v':  current->data = string("\v");  break;
      case '\\': current->data = string("\\");  break;
      default:   current->data = string(1, *p); break;
      }
      continue;
    }

    ++p;
    while (*p == '-') {
      switch (*p) {
      case '-':
        current->add_flags(ELEMENT_ALIGN_LEFT);
        break;
      }
      ++p;
    }

    std::size_t num = 0;
    while (*p && std::isdigit(*p)) {
      num *= 10;
      num += static_cast<std::size_t>(*p++ - '0');
    }
    current->min_width = num;

    if (*p == '.') {
      ++p;
      num = 0;
      while (*p && std::isdigit(*p)) {
        num *= 10;
        num += static_cast<std::size_t>(*p++ - '0');
      }
      current->max_width = num;
      if (current->min_width == 0)
        current->min_width = current->max_width;
    }

    switch (*p) {
    case '%':
      current->type = element_t::STRING;
      current->data = string("%");
      break;

    case '$': {
      if (! tmpl)
        throw_(format_error, _("Prior field reference, but no template"));

      p++;
      if (*p == '0' || (! std::isdigit(*p) &&
                        *p != 'A' && *p != 'B' && *p != 'C' &&
                        *p != 'D' && *p != 'E' && *p != 'F'))
        throw_(format_error, _("%$ field reference must be a digit from 1-9"));

      int         index     = std::isdigit(*p) ? *p - '0' : (*p - 'A' + 10);
      element_t * tmpl_elem = tmpl->elements.get();

      for (int i = 1; i < index && tmpl_elem; i++) {
        tmpl_elem = tmpl_elem->next.get();
        while (tmpl_elem && tmpl_elem->type != element_t::EXPR)
          tmpl_elem = tmpl_elem->next.get();
      }

      if (! tmpl_elem)
        throw_(format_error, _("%$ reference to a non-existent prior field"));

      *current = *tmpl_elem;
      break;
    }

    case '(':
    case '{': {
      bool format_amount = *p == '{';
      if (format_amount) p++;

      current->type = element_t::EXPR;
      current->data = parse_single_expression(p, ! format_amount);

      // Wrap the subexpression in calls to justify and scrub
      if (format_amount) {
        if (! *p || *(p + 1) != '}')
          throw_(format_error, _("Expected closing brace"));
        else
          p++;

        expr_t::ptr_op_t op = boost::get<expr_t>(current->data).get_op();

        expr_t::ptr_op_t amount_op;
        expr_t::ptr_op_t colorize_op;
        if (op->kind == expr_t::op_t::O_CONS) {
          amount_op   = op->left();
          colorize_op = op->has_right() ? op->right() : NULL;
        } else {
          amount_op = op;
        }

        expr_t::ptr_op_t scrub_node(new expr_t::op_t(expr_t::op_t::IDENT));
        scrub_node->set_ident("scrub");

        expr_t::ptr_op_t call1_node(new expr_t::op_t(expr_t::op_t::O_CALL));
        call1_node->set_left(scrub_node);
        call1_node->set_right(amount_op);

        expr_t::ptr_op_t arg1_node(new expr_t::op_t(expr_t::op_t::VALUE));
        expr_t::ptr_op_t arg2_node(new expr_t::op_t(expr_t::op_t::VALUE));
        expr_t::ptr_op_t arg3_node(new expr_t::op_t(expr_t::op_t::VALUE));

        arg1_node->set_value(current->min_width > 0 ?
                             long(current->min_width) : -1);
        arg2_node->set_value(current->max_width > 0 ?
                             long(current->max_width) : -1);
        arg3_node->set_value(! current->has_flags(ELEMENT_ALIGN_LEFT));

        current->min_width = 0;
        current->max_width = 0;

        expr_t::ptr_op_t args1_node(new expr_t::op_t(expr_t::op_t::O_CONS));
        args1_node->set_left(arg2_node);
        args1_node->set_right(arg3_node);

        expr_t::ptr_op_t args2_node(new expr_t::op_t(expr_t::op_t::O_CONS));
        args2_node->set_left(arg1_node);
        args2_node->set_right(args1_node);

        expr_t::ptr_op_t args3_node(new expr_t::op_t(expr_t::op_t::O_CONS));
        args3_node->set_left(call1_node);
        args3_node->set_right(args2_node);

        expr_t::ptr_op_t seq1_node(new expr_t::op_t(expr_t::op_t::O_SEQ));
        seq1_node->set_left(args3_node);

        expr_t::ptr_op_t justify_node(new expr_t::op_t(expr_t::op_t::IDENT));
        justify_node->set_ident("justify");

        expr_t::ptr_op_t call2_node(new expr_t::op_t(expr_t::op_t::O_CALL));
        call2_node->set_left(justify_node);
        call2_node->set_right(seq1_node);

        string prev_expr = boost::get<expr_t>(current->data).text();

        if (colorize_op) {
          expr_t::ptr_op_t ansify_if_node(new expr_t::op_t(expr_t::op_t::IDENT));
          ansify_if_node->set_ident("ansify_if");

          expr_t::ptr_op_t args4_node(new expr_t::op_t(expr_t::op_t::O_CONS));
          args4_node->set_left(call2_node);
          args4_node->set_right(colorize_op);

          expr_t::ptr_op_t seq2_node(new expr_t::op_t(expr_t::op_t::O_SEQ));
          seq2_node->set_left(args4_node);

          expr_t::ptr_op_t call3_node(new expr_t::op_t(expr_t::op_t::O_CALL));
          call3_node->set_left(ansify_if_node);
          call3_node->set_right(seq2_node);

          current->data = expr_t(call3_node);
        } else {
          current->data = expr_t(call2_node);
        }

        boost::get<expr_t>(current->data).set_text(prev_expr);
      }
      break;
    }

    default:
      throw_(format_error, _("Unrecognized formatting character: %1") << *p);
    }
  }

  if (q != buf) {
    if (! result.get()) {
      result.reset(new element_t);
      current = result.get();
    } else {
      current->next.reset(new element_t);
      current = current->next.get();
    }
    current->type = element_t::STRING;
    current->data = string(buf, q);
  }

  return result.release();
}

string format_t::real_calc(scope_t& scope)
{
  std::ostringstream out_str;

  for (element_t * elem = elements.get(); elem; elem = elem->next.get()) {
    std::ostringstream out;
    string name;

    if (elem->has_flags(ELEMENT_ALIGN_LEFT))
      out << std::left;
    else
      out << std::right;

    switch (elem->type) {
    case element_t::STRING:
      if (elem->min_width > 0)
        out.width(static_cast<std::streamsize>(elem->min_width));
      out << boost::get<string>(elem->data);
      break;

    case element_t::EXPR: {
      expr_t& expr(boost::get<expr_t>(elem->data));
      try {

        expr.compile(scope);

        value_t value;
        if (expr.is_function()) {
          call_scope_t args(scope);
          args.push_back(long(elem->max_width));
          value = expr.get_function()(args);
        } else {
          value = expr.calc(scope);
        }
        DEBUG("format.expr", "value = (" << value << ")");

        if (elem->min_width > 0)
          value.print(out, static_cast<int>(elem->min_width), -1,
                      ! elem->has_flags(ELEMENT_ALIGN_LEFT));
        else
          out << value.to_string();
      }
      catch (const calc_error&) {
        string current_context = error_context();

        add_error_context(_("While calculating format expression:"));
        add_error_context(expr.context_to_str());

        if (! current_context.empty())
          add_error_context(current_context);
        throw;
      }
      break;
    }
    }

    if (elem->max_width > 0 || elem->min_width > 0) {
      unistring temp(out.str());
      string    result;

      if (elem->max_width > 0 && elem->max_width < temp.length()) {
        result = truncate(temp, elem->max_width);
      } else {
        result = temp.extract();
        if (elem->min_width > temp.length())
          for (std::size_t i = 0; i < elem->min_width - temp.length(); i++)
            result += " ";
      }
      out_str << result;
    } else {
      out_str << out.str();
    }
  }

  return out_str.str();
}

string format_t::truncate(const unistring&  ustr,
                          const std::size_t width,
                          const std::size_t account_abbrev_length)
{
  assert(width < 4095);

  const std::size_t len = ustr.length();
  if (width == 0 || len <= width)
    return ustr.extract();

  std::ostringstream buf;

  elision_style_t style = default_style;
  if (account_abbrev_length > 0 && ! default_style_changed)
    style = ABBREVIATE;

  switch (style) {
  case TRUNCATE_LEADING:
    // This method truncates at the beginning.
    buf << ".." << ustr.extract(len - (width - 2), width - 2);
    break;

  case TRUNCATE_MIDDLE:
    // This method truncates in the middle.
    buf << ustr.extract(0, (width - 2) / 2)
        << ".."
        << ustr.extract(len - ((width - 2) / 2 + (width - 2) % 2),
                        (width - 2) / 2 + (width - 2) % 2);
    break;

  case ABBREVIATE:
    if (account_abbrev_length > 0) {
      // The algorithm here is complex, but aims to preserve the most
      // information in the most useful places.
      //
      // Consider: You have an account name like
      // 'Assets:Banking:Check:Register'.  This account name, which is
      // 29 characters long, must be shortened to fit in 20.  How would
      // you shorten it?
      //
      // The approach taken below is to compute the difference, or 9
      // characters, and then distribute this difference semi-evenly
      // among first three segments of the account name, by taking
      // characters until the difference is gone.  Further, earlier
      // segments will give up more of their share of letters than later
      // segments, since the later segments usually contain more useful
      // information.

      // First, chop up the Unicode string into individual segments.
      std::list<string> parts;
      string::size_type beg = 0;
      string strcopy(ustr.extract());
      for (string::size_type pos = strcopy.find(':');
           pos != string::npos;
           beg = pos + 1, pos = strcopy.find(':', beg))
        parts.push_back(string(strcopy, beg, pos - beg));
      parts.push_back(string(strcopy, beg));

      DEBUG("format.abbrev", "Account name: " << strcopy);
      DEBUG("format.abbrev",
            "Must fit a " << len << " char string in " << width << " chars");

      // Figure out the lengths of all the parts.  The last part is
      // always displayed in full, while the former parts are
      // distributed, with the latter parts being longer than the
      // former, but with none shorter than account_abbrev_length.
      std::list<std::size_t> lens;
#if defined(DEBUG_ON)
      int index = 0;
#endif
      for (std::list<string>::iterator i = parts.begin();
           i != parts.end();
           i++) {
        std::size_t l = unistring(*i).length();
        DEBUG("format.abbrev",
              "Segment " << ++index << " is " << l << " chars wide");
        lens.push_back(l);
      }

      // Determine the "overflow", or how many chars in excess we are.

      std::size_t overflow = len - width;
      DEBUG("format.abbrev",
            "There are " << overflow << " chars of overflow");

      // Walk through the first n-1 segments, and start subtracting
      // letters to decrease the overflow.  This is done in multiple
      // passes until the overflow is gone, or we cannot reduce any
      // further.  The calculation to find the amount to remove is:
      //
      //   overflow * (((len(segment) + counter) * iteration) /
      //               (len(string) - len(last_segment) - counter))
      //
      // Where:
      //   overflow - the amount that needs to be removed
      //   counter - starts at n-1 for the first segment, then
      //             decreases by one until it reaches 0 for the
      //             last segment (which is never shortened).
      //             This value is used to weight the shrinkage
      //             so that earlier segments shrink faster.
      //   iteration - starts at 1, increase by 1 for every
      //               iteration of the loop
      //
      // In the example above, we have this account name:
      //
      //   Assets:Banking:Check:Register
      //
      // Therefore, the amount to be removed from Assets is calculated as:
      //
      //   9 * (((6 + 3) * 1) / (29 - 8 - 3)) = ceil(4.5) = 5
      //
      // However, since removing 5 chars would make the length of the
      // segment shorter than the default minimum of 2, we can only
      // remove 4 chars from Assets to reduce the overflow.  And on it
      // goes.
      //
      // The final result will be: As:Ban:Chec:Register

      std::size_t iteration      = 1;
      std::size_t len_minus_last = len - lens.back();
      while (overflow > 0) {
        std::size_t overflow_at_start = overflow;
        DEBUG("format.abbrev",
              "Overflow starting at " << overflow << " chars");
#if defined(DEBUG_ON)
        index = 0;
#endif
        std::size_t counter = lens.size();
        for (std::list<std::size_t>::iterator i = lens.begin();
             i != lens.end();
             i++) {
          if (--counter == 0 || overflow == 0)
            break;
          DEBUG("format.abbrev", "Overflow is " << overflow << " chars");
          std::size_t adjust;
          if (overflow == 1)
            adjust = 1;
          else
            adjust = std::size_t
              (std::ceil(double(overflow) *
                         ((double(*i + counter*3) * double(iteration)) /
                          (double(len_minus_last) - double(counter)))));
          DEBUG("format.abbrev", "Weight calc: (" << overflow
                << " * (((" << *i << " + " << counter << ") * "
                << iteration << ") / (" << len_minus_last
                << " - " << counter << ")))");
          if (adjust == 0)
            adjust = 1;
          else if (adjust > overflow)
            adjust = overflow;
          DEBUG("format.abbrev", "The weighted part is " << adjust << " chars");
          std::size_t slack = *i - std::min(*i, account_abbrev_length);
          if (adjust > slack)
            adjust = slack;
          if (adjust > 0) {
            DEBUG("format.abbrev",
                  "Reducing segment " << ++index << " by " << adjust << " chars");
            (*i) -= adjust;
            DEBUG("format.abbrev",
                  "Segment " << index << " is now " << *i << " chars wide");
            overflow -= adjust;
            DEBUG("format.abbrev", "Overflow is now " << overflow << " chars");
          }
        }
        DEBUG("format.abbrev",
              "Overflow ending this time at " << overflow << " chars");
        if (overflow == overflow_at_start)
          break;
        iteration++;
      }

      assert(parts.size() == lens.size());

      std::list<string>::iterator      i = parts.begin();
      std::list<std::size_t>::iterator l = lens.begin();
      std::ostringstream               result;

      for (; i != parts.end() && l != lens.end(); i++, l++) {
        std::list<string>::iterator x = i;
        if (++x == parts.end()) {
          result << *i;
          break;
        }

        unistring temp(*i);
        if (temp.length() > *l)
          result << temp.extract(0, *l) << ":";
        else
          result << *i << ":";
      }

      if (overflow > 0) {
        // Even abbreviated its too big to show the last account, so
        // abbreviate all but the last and truncate at the beginning.
        unistring temp(result.str());
        assert(temp.length() > width - 2);
        buf << ".." << temp.extract(temp.length() - (width - 2), width - 2);
      } else {
        buf << result.str();
      }
      break;
    }
    // fall through...

  case TRUNCATE_TRAILING:
    // This method truncates at the end (the default).
    buf << ustr.extract(0, width - 2) << "..";
    break;
  }

  return buf.str();
}

} // namespace ledger