/**
 * \file vspace.C
 * Copyright 1995-2002 the LyX Team
 * Read the file COPYING
 *
 * \author Matthias Ettrich
 */

#include <config.h>

#ifdef __GNUG__
#pragma implementation
#endif

#include "vspace.h"
#include "lengthcommon.h"
#include "lyx_main.h"
#include "buffer.h"
#include "lyxrc.h"
#include "lyxtext.h"
#include "BufferView.h"
#include "support/LAssert.h"

#include "support/lstrings.h"

#include <cstdio>


namespace {

/// used to return numeric values in parsing vspace
double number[4] = { 0, 0, 0, 0 };
/// used to return unit types in parsing vspace
LyXLength::UNIT unit[4] = { LyXLength::UNIT_NONE,
			    LyXLength::UNIT_NONE,
			    LyXLength::UNIT_NONE,
			    LyXLength::UNIT_NONE };

/// the current position in the number array
int number_index;
/// the current position in the unit array
int unit_index;

/// skip n characters of input
inline
void lyx_advance(string & data, string::size_type n)
{
	data.erase(0, n);
}

/// return true when the input is at the end
inline
bool isEndOfData(string const & data)
{
	return frontStrip(data).empty();
}

/**
 * nextToken -  return the next token in the input
 * @param data input string
 * @return a char representing the type of token returned
 *
 * The possible return values are : 
 * 	+	stretch indicator for glue length
 *	-	shrink indicator for glue length
 *	n	a numeric value (stored in number array)
 *	u	a unit type (stored in unit array)
 *	E	parse error
 */
char nextToken(string & data)
{
	data = frontStrip(data);
	if (data.empty())
		return '\0';
	else if (data[0] == '+') {
		lyx_advance(data, 1);
		return '+';
	} else if (prefixIs(data, "plus")) {
		lyx_advance(data, 4);
		return '+';
	} else if (data[0] == '-') {
		lyx_advance(data, 1);
		return '-';
	} else if (prefixIs(data, "minus")) {
		lyx_advance(data, 5);
		return '-';
	} else {
		string::size_type i = data.find_first_not_of("0123456789.");

		if (i != 0) {
			if (number_index > 3) return 'E';

			string buffer;
		
			// we have found some number
			if (i == string::npos) {
				buffer = data;
				i = data.size() + 1;
			} else
				buffer = data.substr(0, i);

			lyx_advance(data, i);

			if (isStrDbl(buffer)) {
				number[number_index] = strToDbl(buffer);
				++number_index;
				return 'n';
			} else return 'E';
		}
		
		i = data.find_first_not_of("abcdefghijklmnopqrstuvwxyz%");
		if (i != 0) {
			if (unit_index > 3) return 'E';

			string buffer;
		
			// we have found some alphabetical string
			if (i == string::npos) {
				buffer = data;
				i = data.size() + 1;
			} else
				buffer = data.substr(0, i);

			// possibly we have "mmplus" string or similar
			if (buffer.size() > 5 && (buffer.substr(2,4) == string("plus") || buffer.substr(2,5) == string("minus"))) {
				lyx_advance(data, 2);
				unit[unit_index] = unitFromString(buffer.substr(0, 2));
			} else {
				lyx_advance(data, i);
				unit[unit_index] = unitFromString(buffer);
			}

			if (unit[unit_index] != LyXLength::UNIT_NONE) {
				++unit_index;
				return 'u';
			} else return 'E';  // Error
		}
		return 'E';  // Error
	}
}


/// latex representation of a vspace
struct LaTeXLength {
	char const * pattern;
	int  plus_val_index;
	int  minus_val_index;
	int  plus_uni_index;
	int  minus_uni_index;
};


/// the possible formats for a vspace string
LaTeXLength table[] = {
	{ "nu",       0, 0, 0, 0 },
	{ "nu+nu",    2, 0, 2, 0 },
	{ "nu+nu-nu", 2, 3, 2, 3 },
	{ "nu+-nu",   2, 2, 2, 2 },
	{ "nu-nu",    0, 2, 0, 2 },
	{ "nu-nu+nu", 3, 2, 3, 2 },
	{ "nu-+nu",   2, 2, 2, 2 },
	{ "n+nu",     2, 0, 1, 0 },
	{ "n+n-nu",   2, 3, 1, 1 },
	{ "n+-nu",    2, 2, 1, 1 },
	{ "n-nu",     0, 2, 0, 1 },
	{ "n-n+nu",   3, 2, 1, 1 },
	{ "n-+nu",    2, 2, 1, 1 },
	{ "",         0, 0, 0, 0 }   // sentinel, must be empty
};


} // namespace anon

const char * stringFromUnit(int unit)
{
	if (unit < 0 || unit >= num_units)
		return 0;
	return unit_name[unit];
}


bool isValidGlueLength(string const & data, LyXGlueLength * result)
{
	// This parser is table-driven.  First, it constructs a "pattern"
	// that describes the sequence of tokens in "data".  For example,
	// "n-nu" means: number, minus sign, number, unit.  As we go along,
	// numbers and units are stored into static arrays.  Then, "pattern"
	// is searched in the "table".  If it is found, the associated
	// table entries tell us which number and unit should go where
	// in the LyXLength structure.  Example: if "data" has the "pattern"
	// "nu+nu-nu", the associated table entries are "2, 3, 2, 3".
	// That means, "plus_val" is the second number that was seen
	// in the input, "minus_val" is the third number, and "plus_uni"
	// and "minus_uni" are the second and third units, respectively.
	// ("val" and "uni" are always the first items seen in "data".)
	// This is the most elegant solution I could find -- a straight-
	// forward approach leads to very long, tedious code that would be
	// much harder to understand and maintain. (AS)

	if (data.empty())
		return true;
	string buffer = frontStrip(data);

	// To make isValidGlueLength recognize negative values as
	// the first number this little hack is needed:
	int val_sign = 1; // positive as default
	switch (buffer[0]) {
	case '-':
		lyx_advance(buffer, 1);
		val_sign = -1;
		break;
	case '+':
		lyx_advance(buffer, 1);
		// fall through
	default:
		// no action
		break;
	}
	// end of hack
	
	int  pattern_index = 0;
	int  table_index = 0;
	char pattern[20];

	number_index = 1;
	unit_index = 1;  // entries at index 0 are sentinels

	// construct "pattern" from "data"
	while (!isEndOfData (buffer)) {
		if (pattern_index > 20) return false;
		pattern[pattern_index] = nextToken (buffer);
		if (pattern[pattern_index] == 'E') return false;
		++pattern_index;
	}
	pattern[pattern_index] = '\0';

	// search "pattern" in "table"
	table_index = 0;
	while (compare(pattern, table[table_index].pattern)) {
		++table_index;
		if (!*table[table_index].pattern)
			return false;
	}
	
	// Get the values from the appropriate places.  If an index
	// is zero, the corresponding array value is zero or UNIT_NONE,
	// so we needn't check this.
	if (result) {
		result->len_.value  (number[1] * val_sign);
		result->len_.unit   (unit[1]);
		result->plus_.value (number[table[table_index].plus_val_index]);
		result->plus_.unit  (unit  [table[table_index].plus_uni_index]);
		result->minus_.value(number[table[table_index].minus_val_index]);
		result->minus_.unit (unit  [table[table_index].minus_uni_index]);
	}
	return true;
}


bool isValidLength(string const & data, LyXLength * result)
{
	// This is a trimmed down version of isValidGlueLength.
	// The parser may seem overkill for lengths without
	// glue, but since we already have it, using it is
	// easier than writing something from scratch.
	if (data.empty())
		return true;

	string   buffer = data;
	int      pattern_index = 0;
	char     pattern[3];

	// To make isValidLength recognize negative values
	// this little hack is needed:
	int val_sign = 1; // positive as default
	switch (buffer[0]) {
	case '-':
		lyx_advance(buffer, 1);
		val_sign = -1;
		break;
	case '+':
		lyx_advance(buffer, 1);
		// fall through
	default:
		// no action
		break;
	}
	// end of hack
	
	number_index = unit_index = 1;  // entries at index 0 are sentinels

	// construct "pattern" from "data"
	while (!isEndOfData (buffer)) {
		if (pattern_index > 2)
			return false;
		pattern[pattern_index] = nextToken (buffer);
		if (pattern[pattern_index] == 'E')
			return false;
		++pattern_index;
	}
	pattern[pattern_index] = '\0';

	// only the most basic pattern is accepted here
	if (compare(pattern, "nu") != 0) return false;		
	
	// It _was_ a correct length string.
	// Store away the values we found.
	if (result) {
		result->val_  = number[1] * val_sign;
		result->unit_ = unit[1];
	}
	return true;
}


//
//  VSpace class
//

VSpace::VSpace()
	: kind_(NONE), len_(), keep_(false)
{}


VSpace::VSpace(vspace_kind k)
	: kind_(k), len_(), keep_(false)
{}


VSpace::VSpace(LyXLength const & l)
	: kind_(LENGTH), len_(l), keep_(false)
{}


VSpace::VSpace(LyXGlueLength const & l)
	: kind_(LENGTH), len_(l), keep_(false)
{}


VSpace::VSpace(string const & data)
	: kind_(NONE), len_(), keep_(false)
{
	if (data.empty())
		return;
	double value;
	string input  = strip(data);

	string::size_type const length = input.length();

	if (length > 1 && input[length-1] == '*') {
		keep_ = true;
		input.erase(length - 1);
	}

	if      (prefixIs (input, "defskip"))    kind_ = DEFSKIP;
	else if (prefixIs (input, "smallskip"))  kind_ = SMALLSKIP;
	else if (prefixIs (input, "medskip"))    kind_ = MEDSKIP;
	else if (prefixIs (input, "bigskip"))    kind_ = BIGSKIP;
	else if (prefixIs (input, "vfill"))      kind_ = VFILL;
	else if (isValidGlueLength(input, &len_)) kind_ = LENGTH;
	else if (sscanf(input.c_str(), "%lf", &value) == 1) {
		// This last one is for reading old .lyx files
		// without units in added_space_top/bottom.
		// Let unit default to centimeters here.
		kind_ = LENGTH;
		len_  = LyXGlueLength(LyXLength(value, LyXLength::CM));
	}
}


VSpace::vspace_kind VSpace::kind() const
{
	return kind_;
}


LyXGlueLength VSpace::length() const
{
	return len_;
}


bool VSpace::keep() const
{
	return keep_;
}


void VSpace::setKeep(bool val)
{
	keep_ = val;
}


bool VSpace::operator==(VSpace const & other) const
{
	if (kind_ != other.kind_)
		return false;

	if (kind_ != LENGTH)
		return this->keep_ == other.keep_;

	if (len_ != other.len_)
		return false;

	return keep_ == other.keep_;
}


string const VSpace::asLyXCommand() const
{
	string result;
	switch (kind_) {
	case NONE:      break;
	case DEFSKIP:   result = "defskip";      break;
	case SMALLSKIP: result = "smallskip";    break;
	case MEDSKIP:   result = "medskip";      break;
	case BIGSKIP:   result = "bigskip";      break;
	case VFILL:     result = "vfill";        break;
	case LENGTH:    result = len_.asString(); break;
	}
	if (keep_ && kind_ != NONE && kind_ != DEFSKIP)
		result += '*';
	return result;
}


string const VSpace::asLatexCommand(BufferParams const & params) const
{
	string ret;

	switch (kind_) {
	case NONE:
		break;
	case DEFSKIP:
		ret = params.getDefSkip().asLatexCommand(params);
		break;
	case SMALLSKIP:
		ret = keep_ ? "\\vspace*{\\smallskipamount}"
			: "\\smallskip{}";
		break;
	case MEDSKIP:
		ret = keep_ ? "\\vspace*{\\medskipamount}"
			: "\\medskip{}";
		break;
	case BIGSKIP:
		ret = keep_ ? "\\vspace*{\\bigskipamount}"
			: "\\bigskip{}";
		break;
	case VFILL:
		ret = keep_ ? "\\vspace*{\\fill}"
			: "\\vfill{}";
		break;
	case LENGTH:
	{
		string const lenstr = len_.asLatexString();
		
		ret = keep_ ? "\\vspace*{" + lenstr + '}'
			: "\\vspace{" + lenstr + '}';
	}
	break;

	}
	
	return ret;
}



int VSpace::inPixels(BufferView * bv) const
{
	// Height of a normal line in pixels (zoom factor considered)
	int const default_height = bv->text->defaultHeight(); // [pixels]

	int retval = 0;
	
	switch (kind_) {
	case NONE:
		// Value for this is already set
		break;
	case DEFSKIP:
		retval = bv->buffer()->params.getDefSkip().inPixels(bv);
		break;
			
		// This is how the skips are normally defined by
		// LateX.  But there should be some way to change
		// this per document.
	case SMALLSKIP:
		retval = default_height / 4;
		break;
			
	case MEDSKIP:
		retval = default_height / 2;
		break;
			
	case BIGSKIP:
		retval = default_height;
		break;

	case VFILL:
		// leave space for the vfill symbol
		retval = 3 * default_height;
		break;
		
	case LENGTH: {
		int const default_width  = bv->workWidth();
		retval = len_.len().inPixels(default_width, default_height);
		break;
	}
		
	}
	return retval;
}