#include "PolishNotationParser.h"
#include "MemoryData.h"

#include <iostream>

Instruction::Instruction(const char* str, unsigned argc, void (*exec)(Memory&)) : name(str), argc(argc), exec(exec) {}

Atom::Atom(bool (*isAtomChar)(char), MemoryData* (*absorb)(ifstream&)) : isAtomChar(isAtomChar), absorb(absorb) {}

void PNParser::addInstr(Instruction i) {
	this->instr.push_back(i);
}

void PNParser::addAtom(Atom a) {
	this->atoms.push_back(a);
}

bool isSpacing(char ch) {
	return ch == ' ' || ch == '\t' || ch == EOF;
}

void skipSpacing(ifstream& inFile) {
	while(isSpacing(inFile.peek()))
		inFile.get();
}

void PNParser::evaluateFunction(Memory& mem, Function* func, ifstream& inFile) {
	if (func->scopeEnd < 0) {
		instr[func->scopeStart].exec(mem);
		delete func;
		return;
	}

	for (auto i = func->argumentNames.rbegin(); i != func->argumentNames.rend(); ++i) {
		mem.vars.push_back(new Name(*i));
		mem.vars.push_back(mem.work.top());
		mem.work.pop();
	}
	mem.scopeVars.push(func->argumentNames.size());

	this->parseScope(inFile, mem, func->scopeStart, func->scopeEnd);
}

void PNParser::pushToWork(Memory& mem, MemoryData* data, ifstream& inFile) {
	if (data->get_type() == MemoryData::TFunc) {
		Function* func = static_cast<Function*>(data);
		mem.work.push(data);
		mem.work.push(new Int(func->argumentNames.size()));
		return;
	}

	// We keep the amount of required arguments and the function
	// on the top of the stack at all times
	Int* argc = static_cast<Int*>(mem.work.top());
	mem.work.pop();
	Function* func = static_cast<Function*>(mem.work.top());
	mem.work.pop();

	mem.work.push(data);
	argc->value--;

	while (argc->value == 0) {
		delete argc;
		evaluateFunction(mem, func, inFile);
		
		if (mem.work.size() == 1) return;

		data = mem.work.top();
		mem.work.pop();
		argc = static_cast<Int*>(mem.work.top());
		mem.work.pop();
		func = static_cast<Function*>(mem.work.top());
		mem.work.pop();

		mem.work.push(data);
		argc->value--;
	}

	mem.work.push(func);
	mem.work.push(argc);
}

void PNParser::parseScope(ifstream& inFile, Memory& mem, int start, int end) {
	mem.scopeVars.push(0);
	bool absorbed = false;
	while (start < inFile.tellg() && inFile.tellg() < end && inFile.peek() != EOF) {
		skipSpacing(inFile);

		/* If value is an atom */

		for (Atom& a : this->atoms) {
			if (a.isAtomChar(inFile.peek())) {
				pushToWork(mem, a.absorb(inFile), inFile);
				absorbed = true;
				break;
			}
		}

		if (absorbed) { absorbed = false; continue; }

		/* If value is a built-in function */

		string name;
		while (!isSpacing(inFile.peek()))
			name.push_back(inFile.get());

		for (int i = instr.size() - 1; i >= 0; i--) {
			if (instr[i].name == name) {
				list<string> temp;
				temp.resize(instr[i].argc);
				pushToWork(mem, new Function(temp, i, -1), inFile);
				absorbed = true;
				break;
			}
		}

		if (absorbed) { absorbed = false; continue; }

		/* If value is a variable */

		Name* cname;
		for (auto i = ++mem.vars.rbegin(); i != mem.vars.rend(); ++(++i)) {
			cname = static_cast<Name*>(*i);
			if (cname->value == name) {
				MemoryData* value = new MemoryData(*static_cast<MemoryData*>(*(--i)));
				pushToWork(mem, value, inFile);
				break;
			}
		}
	}
	cout << mem.vars.size();
	// cout << static_cast<Int*>(mem.work.top())->value << endl;

	for (int i = mem.scopeVars.top(); i > 0; i--) {
		delete mem.vars.back();
		mem.vars.pop_back();
		delete mem.vars.back();
		mem.vars.pop_back();
	}
	mem.scopeVars.pop();
}

void PNParser::parse(ifstream& inFile, Memory& mem) {
	parseScope(inFile, mem, -1, 100000); // global scope
}