// This file contains most of the magic that extracts "context
// information" from the unstructered layout-oriented stuff in an
// MathArray.

#include <algorithm>

#include "math_charinset.h"
#include "math_deliminset.h"
#include "math_diffinset.h"
#include "math_exfuncinset.h"
#include "math_exintinset.h"
#include "math_funcinset.h"
#include "math_fracinset.h"
#include "math_matrixinset.h"
#include "math_mathmlstream.h"
#include "math_scriptinset.h"
#include "math_stringinset.h"
#include "math_symbolinset.h"
#include "Lsstream.h"
#include "debug.h"


std::ostream & operator<<(std::ostream & os, MathArray const & ar)
{
	NormalStream ns(os);	
	ns << ar;
	return os;
}


// define a function for tests
typedef bool TestItemFunc(MathInset *);

// define a function for replacing subexpressions
typedef MathInset * ReplaceArgumentFunc(const MathArray & ar);



// try to extract a super/subscript 
// modify iterator position to point behind the thing
bool extractScript(MathArray & ar,
	MathArray::iterator & pos, MathArray::iterator last)
{
	// nothing to get here
	if (pos == last)
		return false;

	// is this a scriptinset?
	if (!(*pos)->asScriptInset())
		return false;

	// it is a scriptinset, use it.
	ar.push_back(*pos);
	++pos;
	return true;
}


// try to extract an "argument" to some function.
// returns position behind the argument
MathArray::iterator extractArgument(MathArray & ar,
	MathArray::iterator pos, MathArray::iterator last, string const & = "")
{
	// nothing to get here
	if (pos == last)
		return pos;

	// something deliminited _is_ an argument
	if ((*pos)->asDelimInset()) {
		ar.push_back(*pos);
		return pos + 1;
	}

	// always take the first thing, no matter what it is
	ar.push_back(*pos);

	// go ahead if possible
	++pos;
	if (pos == last)
		return pos;

	// if the next item is a subscript, it most certainly belongs to the
	// thing we have
	extractScript(ar, pos, last);
	if (pos == last)
		return pos;

	// but it might be more than that.
	// FIXME: not implemented
	//for (MathArray::iterator it = pos + 1; it != last; ++it) {
	//	// always take the first thing, no matter
	//	if (it == pos) {
	//		ar.push_back(*it);
	//		continue;
	//	}
	//}
	return pos;
}


MathScriptInset const * asScript(MathArray::const_iterator it)
{
	if (it->nucleus()->asScriptInset())
		return 0;
	++it;
	if (!it->nucleus())
		return 0;
	return it->nucleus()->asScriptInset();
}



// returns sequence of char with same code starting at it up to end
// it might be less, though...
MathArray::const_iterator charSequence(MathArray::const_iterator it,
	MathArray::const_iterator end, string & s, MathTextCodes & c)
{
	MathCharInset const * p = (*it)->asCharInset();
	c = p->code();
	for (; it != end; ++it) {
		p = (*it)->asCharInset();
		if (!p || p->code() != c)
			break;
		s += p->getChar();
	}
	return it;
}


void extractStrings(MathArray & ar)
{
	//lyxerr << "\nStrings from: " << ar << "\n";
	for (MathArray::size_type i = 0; i < ar.size(); ++i) {
		MathArray::iterator it = ar.begin() + i;
		if (!(*it)->asCharInset())
			continue;

		// create proper string inset
		MathStringInset * p = new MathStringInset;
		MathArray::const_iterator
			jt = charSequence(it, ar.end(), p->str_, p->code_);

		// clean up
		(*it).reset(p);
		ar.erase(i + 1, jt - ar.begin());
	}
	//lyxerr << "\nStrings to: " << ar << "\n";
}


MathInset * singleItem(MathArray & ar)
{
	return ar.size() == 1 ? ar.begin()->nucleus() : 0;
}


void extractMatrices(MathArray & ar)
{
	lyxerr << "\nMatrices from: " << ar << "\n";
	for (MathArray::iterator it = ar.begin(); it != ar.end(); ++it) {
		MathDelimInset * del = (*it)->asDelimInset();
		if (!del)
			continue;
		MathInset * arr = singleItem(del->cell(0));
		if (!arr || !arr->asArrayInset())
			continue;
		*it = MathAtom(new MathMatrixInset(*(arr->asArrayInset())));
	}
	lyxerr << "\nMatrices to: " << ar << "\n";
}


// convert this inset somehow to a string
bool extractString(MathInset * p, string & str)
{
	if (!p)
		return false;
	if (p->getChar()) {
		str = string(1, p->getChar());
		return true;
	}
	if (p->asStringInset()) {
		str = p->asStringInset()->str();
		return true;
	}
	return false;
}


// convert this inset somehow to a number
bool extractNumber(MathArray const & ar, int & i)
{
	string s;
	MathTextCodes c;
	charSequence(ar.begin(), ar.end(), s, c);
	std::istringstream is(s);
	is >> i;
	return is;
}


bool testString(MathInset * p, const string & str)
{
	string s;
	return extractString(p, s) && str == s;
}


// search end of nested sequence
MathArray::iterator endNestSearch(
	MathArray::iterator it,
	MathArray::iterator last,
	TestItemFunc testOpen,
	TestItemFunc testClose
)
{
	for (int level = 0; it != last; ++it) {
		if (testOpen(it->nucleus()))
			++level;
		if (testClose(it->nucleus()))
			--level;
		if (level == 0)
			break;
	}
	return it;
}


// replace nested sequences by a real Insets
void replaceNested(
	MathArray & ar,
	TestItemFunc testOpen,
	TestItemFunc testClose,
	ReplaceArgumentFunc replaceArg
)
{
	// use indices rather than iterators for the loop  because we are going
	// to modify the array.
	for (MathArray::size_type i = 0; i < ar.size(); ++i) {
		// check whether this is the begin of the sequence
		MathArray::iterator it = ar.begin() + i;
		if (!testOpen(it->nucleus()))
			continue;

		// search end of sequence
		MathArray::iterator jt = endNestSearch(it, ar.end(), testOpen, testClose);
		if (jt == ar.end())
			continue;

		// create a proper inset as replacement
		MathInset * p = replaceArg(MathArray(it + 1, jt));

		// replace the original stuff by the new inset
		ar.erase(it + 1, jt + 1);
		(*it).reset(p);
	}
} 



//
// split scripts into seperate super- and subscript insets. sub goes in
// front of super... 
//

void splitScripts(MathArray & ar)
{
	lyxerr << "\nScripts from: " << ar << "\n";
	for (MathArray::size_type i = 0; i < ar.size(); ++i) {
		MathArray::iterator it = ar.begin() + i;

		// is this script inset?
		MathScriptInset * p = (*it)->asScriptInset();
		if (!p)
			continue;

		// no problem if we don't have both...
		if (!p->hasUp() || !p->hasDown())
			continue;

		// create extra script inset and move superscript over
		MathScriptInset * q = new MathScriptInset;
		q->ensure(true); 
		q->up().data_.swap(p->up().data_);
		p->removeScript(true);

		// insert new inset behind
		++i;
		ar.insert(i, MathAtom(q)); 
	}
	lyxerr << "\nScripts to: " << ar << "\n";
}



//
// search deliminiters
//

bool testOpenParan(MathInset * p)
{
	return testString(p, "(");
}


bool testCloseParan(MathInset * p)
{
	return testString(p, ")");
}


MathInset * replaceDelims(const MathArray & ar)
{
	MathDelimInset * del = new MathDelimInset("(", ")");
	del->cell(0) = ar;
	return del;
}


// replace '('...')' sequences by a real MathDelimInset
void extractDelims(MathArray & ar)
{
	lyxerr << "\nDelims from: " << ar << "\n";
	replaceNested(ar, testOpenParan, testCloseParan, replaceDelims);
	lyxerr << "\nDelims to: " << ar << "\n";
}



//
// search well-known functions
//


// replace 'f' '(...)' and 'f' '^n' '(...)' sequences by a real MathExFuncInset
// assume 'extractDelims' ran before
void extractFunctions(MathArray & ar)
{
	// we need at least two items...
	if (ar.size() <= 1)
		return;

	lyxerr << "\nFunctions from: " << ar << "\n";
	for (MathArray::size_type i = 0; i + 1 < ar.size(); ++i) {
		MathArray::iterator it = ar.begin() + i;
		MathArray::iterator jt = it + 1;

		string name;
		// is it a function?
		if ((*it)->asFuncInset()) { 
			// it certainly is if it is well known...
			name = (*it)->asFuncInset()->name();
	 	} else {
			// is this a user defined function?
			// it it probably not, if it doesn't have a name.
			if (!extractString((*it).nucleus(), name))
				continue;
			// it is not if it has no argument
			if (jt == ar.end())
				continue;
			// guess so, if this is followed by
			// a DelimInset with a single item in the cell
			MathDelimInset * del = (*jt)->asDelimInset();
			if (!del || del->cell(0).size() != 1)
				continue;
			// fall trough into main branch
		}

		// do we have an exponent like in
		// 'sin' '^2' 'x' -> 'sin(x)' '^2'
		MathArray exp;
		extractScript(exp, jt, ar.end());
	
		// create a proper inset as replacement
		MathExFuncInset * p = new MathExFuncInset(name);

		// jt points to the "argument". Get hold of this.
		MathArray::iterator st = extractArgument(p->cell(0), jt, ar.end());

		// replace the function name by a real function inset
		(*it).reset(p);
		
		// remove the source of the argument from the array
		ar.erase(it + 1, st);

		// re-insert exponent
		ar.insert(i + 1, exp);
		lyxerr << "\nFunctions to: " << ar << "\n";
	}
} 


//
// search integrals
//

bool testSymbol(MathInset * p, string const & name)
{
	return p->asSymbolInset() && p->asSymbolInset()->name() == name;
}


bool testIntSymbol(MathInset * p)
{
	return testSymbol(p, "int");
}


bool testIntDiff(MathInset * p)
{
	return testString(p, "d");
}


// replace '\int' ['_^'] x 'd''x'(...)' sequences by a real MathExIntInset
// assume 'extractDelims' ran before
void extractIntegrals(MathArray & ar)
{
	// we need at least three items...
	if (ar.size() <= 2)
		return;

	lyxerr << "\nIntegrals from: " << ar << "\n";
	for (MathArray::size_type i = 0; i + 1 < ar.size(); ++i) {
		MathArray::iterator it = ar.begin() + i;

		// is this a integral name?
		if (!testIntSymbol(it->nucleus()))
			continue;

		// search 'd'
		MathArray::iterator jt =
			endNestSearch(it, ar.end(), testIntSymbol, testIntDiff);

		// something sensible found?
		if (jt == ar.end())
			continue;

		// create a proper inset as replacement
		MathExIntInset * p = new MathExIntInset("int");

		// collect subscript if any
		MathArray::iterator st = it + 1;
		if (st != ar.end())
			if (MathScriptInset * sub = (*st)->asScriptInset()) 
				if (sub->hasDown()) {
					p->cell(2) = sub->down().data_;
					++st;
				}

		// collect superscript if any
		if (st != ar.end())
			if (MathScriptInset * sup = (*st)->asScriptInset()) 
				if (sup->hasUp()) {
					p->cell(3) = sup->up().data_;
					++st;
				}

		// core ist part from behind the scripts to the 'd'
		p->cell(0) = MathArray(st, jt);

		// use the "thing" behind the 'd' as differential
		MathArray::iterator tt = extractArgument(p->cell(1), jt + 1, ar.end());
		
		// remove used parts
		ar.erase(it + 1, tt);
		(*it).reset(p);
	}
	lyxerr << "\nIntegrals to: " << ar << "\n";
}


//
// search sums
//

bool testSumSymbol(MathInset * p)
{
	return testSymbol(p, "sum");
}


bool testEqualSign(MathAtom const & at)
{
	return testString(at.nucleus(), "=");
}



// replace '\sum' ['_^'] f(x) sequences by a real MathExIntInset
// assume 'extractDelims' ran before
void extractSums(MathArray & ar)
{
	// we need at least two items...
	if (ar.size() <= 1)
		return;

	lyxerr << "\nSums from: " << ar << "\n";
	for (MathArray::size_type i = 0; i + 1< ar.size(); ++i) {
		MathArray::iterator it = ar.begin() + i;

		// is this a sum name?
		if (!testSumSymbol(it->nucleus()))
			continue;

		// create a proper inset as replacement
		MathExIntInset * p = new MathExIntInset("sum");

		// collect lower bound and summation index
		MathArray::iterator st = it + 1;
		if (st != ar.end())
			if (MathScriptInset * sub = (*st)->asScriptInset())
				if (sub->hasDown()) {
					// try to figure out the summation index from the subscript
					MathArray & ar = sub->down().data_;
					MathArray::iterator it =
						std::find_if(ar.begin(), ar.end(), &testEqualSign);
					if (it != ar.end()) {
						// we found a '=', use everything in front of that as index,
						// and everything behind as lower index
						p->cell(1) = MathArray(ar.begin(), it);
						p->cell(2) = MathArray(it + 1, ar.end());
					} else {
						// use everything as summation index, don't use scripts.
						p->cell(1) = ar;
					}
					++st;
				}

		// collect upper bound
		if (st != ar.end())
			if (MathScriptInset * sup = (*st)->asScriptInset())
				if (sup->hasUp()) {
					p->cell(3) = sup->up().data_;
					++st;
				}

		// use some  behind the script as core
		MathArray::iterator tt = extractArgument(p->cell(0), st, ar.end());

		// cleanup
		ar.erase(it + 1, tt);
		(*it).reset(p);
	}
	lyxerr << "\nSums to: " << ar << "\n";
}


//
// search differential stuff
//

// tests for 'd' or '\partial'
bool testDiffItem(MathAtom const & at)
{
	return testString(at.nucleus(), "d");
}


bool testDiffArray(MathArray const & ar)
{
	return ar.size() && testDiffItem(ar.front());
}


bool testDiffFrac(MathInset * p)
{
	MathFracInset * f = p->asFracInset();
	return f && testDiffArray(f->cell(0)) && testDiffArray(f->cell(1));
}


// is this something like ^number?
bool extractDiffExponent(MathArray::iterator it, int & i)
{
	if (!(*it)->asScriptInset())
		return false;

	string s;
	if (!extractString((*it).nucleus(), s))
		return false;
	std::istringstream is(s);
	is >> i;
	return is;
}


void extractDiff(MathArray & ar)
{
	lyxerr << "\nDiffs from: " << ar << "\n";
	for (MathArray::size_type i = 0; i < ar.size(); ++i) {
		MathArray::iterator it = ar.begin() + i;

		// is this a "differential fraction"?
		if (!testDiffFrac(it->nucleus()))
			continue;
		
		MathFracInset * f = (*it)->asFracInset();
		if (!f) {
			lyxerr << "should not happen\n";
			continue;
		}

		// create a proper diff inset
		MathDiffInset * diff = new MathDiffInset;

		// collect function, let jt point behind last used item
		MathArray::iterator jt = it + 1; 
		int n = 1; 
		MathArray & numer = f->cell(0);
		if (numer.size() > 1 && numer.at(1)->asScriptInset()) {
			// this is something like  d^n f(x) / d... or  d^n / d...
			// FIXME
			n = 1;	
			if (numer.size() > 2) 
				diff->cell(0) = MathArray(numer.begin() + 2, numer.end());
			else
				jt = extractArgument(diff->cell(0), jt, ar.end());
		} else {
			// simply d f(x) / d... or  d/d...
			if (numer.size() > 1) 
				diff->cell(0) = MathArray(numer.begin() + 1, numer.end());
			else
				jt = extractArgument(diff->cell(0), jt, ar.end());
		}

		// collect denominator parts
		MathArray & denom = f->cell(1);
		for (MathArray::iterator dt = denom.begin(); dt != denom.end(); ) {
			// find the next 'd'
			MathArray::iterator et = std::find_if(dt + 1, denom.end(), &testDiffItem);

			// point before this
			MathArray::iterator st = et - 1;
			MathScriptInset * script = (*st)->asScriptInset();
			if (script && script->hasUp()) {
				// things like   d.../dx^n
				int mult = 1;
				if (extractNumber(script->up().data_, mult)) {
					lyxerr << "mult: " << mult << endl;
					for (int i = 0; i < mult; ++i)
						diff->addDer(MathArray(dt + 1, st));
				}
			} else {
				// just  d.../dx
				diff->addDer(MathArray(dt + 1, et));
			}
			dt = et;
		}

		// cleanup
		ar.erase(it + 1, jt);
		(*it).reset(diff);
	}
	lyxerr << "\nDiffs to: " << ar << "\n";
}

//
// combine searches
//

void extractStructure(MathArray & ar)
{
	splitScripts(ar);
	extractMatrices(ar);
	extractDelims(ar);
	extractFunctions(ar);
	extractIntegrals(ar);
	extractSums(ar);
	extractDiff(ar);
	extractStrings(ar);
}


void write(MathArray const & dat, WriteStream & wi)
{
	MathArray ar = dat;
	extractStrings(ar);
	for (MathArray::const_iterator it = ar.begin(); it != ar.end(); ++it) {
		wi.firstitem = (it == ar.begin());
		MathInset const * p = it->nucleus();
		if (it + 1 != ar.end()) {
			if (MathScriptInset const * q = asScript(it)) {
				q->write(p, wi);
				++it;
				continue;
			} 
		}
		p->write(wi);
	}
}


void normalize(MathArray const & ar, NormalStream & os)
{
	for (MathArray::const_iterator it = ar.begin(); it != ar.end(); ++it)
		(*it)->normalize(os);
}


void octavize(MathArray const & dat, OctaveStream & os)
{
	MathArray ar = dat;
	extractStructure(ar);
	for (MathArray::const_iterator it = ar.begin(); it != ar.end(); ++it) {
		MathInset const * p = it->nucleus();
		if (it + 1 != ar.end()) {
			if (MathScriptInset const * q = asScript(it)) {
				q->octavize(p, os);
				++it;	
				continue;
			}
		}
		p->octavize(os);
	}
}


void maplize(MathArray const & dat, MapleStream & os)
{
	MathArray ar = dat;
	extractStructure(ar);
	for (MathArray::const_iterator it = ar.begin(); it != ar.end(); ++it) {
		MathInset const * p = it->nucleus();
		if (it + 1 != ar.end()) {
			if (MathScriptInset const * q = asScript(it)) {
				q->maplize(p, os);
				++it;	
				continue;
			}
		}
		p->maplize(os);
	}
}


void mathmlize(MathArray const & dat, MathMLStream & os)
{
	MathArray ar = dat;
	extractStructure(ar);
	if (ar.size() == 0)
		os << "<mrow/>";
	else if (ar.size() == 1)
		os << ar.begin()->nucleus();
	else {
		os << MTag("mrow");
		for (MathArray::const_iterator it = ar.begin(); it != ar.end(); ++it) {
			MathInset const * p = it->nucleus();
			if (it + 1 != ar.end()) {
				if (MathScriptInset const * q = asScript(it)) {
					q->mathmlize(p, os);
					++it;	
					continue;
				}
			}
			p->mathmlize(os);
		}
		os << ETag("mrow");
	}
}