//*****************************************************************
//
//	$file: scanner.cpp $
//	$author: Martin Fouilleul $
//	$date: 24/12/2017 $
//
//*****************************************************************

/*
------------------------------------------------------------------------------
This software is available under 2 licenses -- choose whichever you prefer.
------------------------------------------------------------------------------
ALTERNATIVE A - MIT License
Copyright (c) 2017 Martin Fouilleul
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
------------------------------------------------------------------------------
ALTERNATIVE B - Public Domain (www.unlicense.org)
This is free and unencumbered software released into the public domain.
Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
software, either in source code form or as a compiled binary, for any purpose,
commercial or non-commercial, and by any means.
In jurisdictions that recognize copyright laws, the author or authors of this
software dedicate any and all copyright interest in the software to the public
domain. We make this dedication for the benefit of the public at large and to
the detriment of our heirs and successors. We intend this dedication to be an
overt act of relinquishment in perpetuity of all present and future rights to
this software under copyright law.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
------------------------------------------------------------------------------
*/

#include<stdio.h>
#include<strings.h>

#include"scanner.h"

static int mode = MODE_TEXT;

const int MAX_LOOK_AHEAD = 15;

bool LookAhead(FILE* input, const char* string)
{
	char buffer[MAX_LOOK_AHEAD+1];
	int len = strlen(string);
	int count = 0;


	while(count<len && count<MAX_LOOK_AHEAD)
	{
		buffer[count] = getc(input);
		if(buffer[count] != string[count])
		{
			break;
		}
		count++;
	}
	if(count != len)
	{
		//NOTE(martin): push back characters and return false
		for(int i=count;i>=0;i--)
		{
			ungetc(buffer[i], input);
		}
		return(false);
	}
	else
	{
		return(true);
	}
}

char Peek(FILE* input)
{
	char c = getc(input);
	ungetc(c, input);
	return(c);
}

void CharacterToken(FILE* input, token* t)
{
	t->type = CHAR;
	t->c = getc(input);
}

void MarkupCharToken(markup_type type, token* t)
{
	t->type = MARKUP;
	t->markup.type = type;
	t->markup.value = 0;
}

void SymbolToken(symbol_code code, token* t)
{
	t->type = SYMBOL;
	t->symbol.code = code;
}


void EndlToken(FILE* input, token* t)
{
	getc(input);
	t->type = ENDL;
}

void AttributedMarkupToken(FILE* input, markup_type type, token* t)
{
	t->type = MARKUP;
	t->markup.type = type;
	int count = 0;
	char c;
	while(((c = getc(input)) != EOF) && count < MAX_MARKUP_TAG_LENGTH)
	{
		if(c==']')
		{
			t->markup.text[count] = '\0';
			return;
		}
		t->markup.text[count] = c;
		count++;
	}
	//error
	return;
}

void BlockToken(FILE* input, token* t)
{
	t->type = MARKUP;

	if( LookAhead(input, "[c]"))
	{
		t->markup.type = CODE_INLINE_START;
		mode = MODE_CODE_INLINE;
	}
	else if(LookAhead(input, "[m]"))
	{
		t->markup.type = MATHS_INLINE_START;
		mode = MODE_MATHS_INLINE;
	}
	else if(LookAhead(input, "[/c]"))
	{
		t->markup.type = CODE_INLINE_STOP;
		mode = MODE_TEXT;
	}
	else if(LookAhead(input, "[/m]"))
	{
		t->markup.type = MATHS_INLINE_STOP;
		mode = MODE_TEXT;
	}
	else if(LookAhead(input, "[code="))
	{
		AttributedMarkupToken(input, CODE_BLOCK_START, t);
		mode = MODE_CODE_BLOCK;
	}
	else if(LookAhead(input, "[code]"))
	{
		t->markup.type = CODE_BLOCK_START;
		mode = MODE_CODE_BLOCK;
	}
	else if(LookAhead(input, "[html]"))
	{
		t->markup.type = HTML_BLOCK_START;
		mode = MODE_HTML;
	}
	else if(LookAhead(input, "[/code]"))
	{
		t->markup.type = CODE_BLOCK_STOP;
		mode = MODE_TEXT;
	}
	else if(LookAhead(input, "[/html]"))
	{
		t->markup.type = HTML_BLOCK_STOP;
		mode = MODE_TEXT;
	}
	else if(LookAhead(input, "[maths]"))
	{
		t->markup.type = MATHS_BLOCK_START;
		mode = MODE_MATHS_BLOCK;
	}
	else if(LookAhead(input, "[/maths]"))
	{
		t->markup.type = MATHS_BLOCK_STOP;
		mode = MODE_TEXT;
	}
	else if(LookAhead(input, "[url="))
	{
		AttributedMarkupToken(input, URL_START, t);
	}
	else if(LookAhead(input, "[/url]"))
	{
		t->markup.type = URL_STOP;
	}
	else if(LookAhead(input, "[img="))
	{
		AttributedMarkupToken(input, IMG, t);
	}
	else
	{
		//TODO(martin): should issue a warning ?
		CharacterToken(input, t);
	}
}

void RepeatableMarkupToken(FILE* input, char m, markup_type type, token* t)
{
	char c;
	int count = 0;
	while((c = getc(input)) == m)
	{
		count++;
	}
	ungetc(c, input);

	t->type = MARKUP;
	t->markup.type = type;
	t->markup.value = count;
}

void LessToken(FILE* input, token* t)
{
	t->html.text[0] = getc(input);
	char c = Peek(input);
	if(   c == '!'
	   || (c >= 'A' && c <= 'Z')
	   || (c >= 'a' && c <= 'z')
	   || c == '/')
	{
		bool quotes = false;
		bool dquotes = false;
		int count = 1;
		while(((c = getc(input)) != EOF) && (count < MAX_HTML_TAG_LENGTH))
		{
			t->html.text[count] = c;

			if(c == '>' && !quotes && !dquotes)
			{
				count++;
				break;
			}
			else if(c == '\'' && !dquotes)
			{
				quotes = !quotes;
			}
			else if(c == '\"' && !quotes)
			{
				dquotes = !dquotes;
			}
			count++;
		}
		if(count >= MAX_HTML_TAG_LENGTH || c == EOF)
		{
			//issue an error
		}
		else
		{
			t->type = HTML_TAG;
			t->html.text[count] = '\0';
		}
	}
	else if(c == '-')
	{
		while(c == '-')
		{
			c = getc(input);
		}
		ungetc(c, input);
		t->type = SYMBOL;
		t->symbol.code = LARR;

	}
	else
	{
		ungetc(t->html.text[0], input);
		CharacterToken(input, t);
	}
}

void EscapeToken(FILE* input, token* t)
{
	getc(input);
	t->type = SYMBOL;

	if(LookAhead(input, "star"))
	{
		t->symbol.code = STAR;
	}
	else if(LookAhead(input, "lowstar"))
	{
		t->symbol.code = LOSTAR;
	}
	else if(LookAhead(input, "minus"))
	{
		SymbolToken(SUBSTRACT, t);
	}
	else if(LookAhead(input, "div"))
	{
		t->symbol.code = DIVIDE;
	}
	else if(LookAhead(input, "cdot"))
	{
		t->symbol.code = CDOT;
	}
	else if(LookAhead(input, "times"))
	{
		t->symbol.code = MULTIPLY;
	}
	else if(LookAhead(input, "otimes"))
	{
		t->symbol.code = OTIMES;
	}
	else if(LookAhead(input, "leq"))
	{
		t->symbol.code = LEQ;
	}
	else if(LookAhead(input, "geq"))
	{
		t->symbol.code = GEQ;
	}
	else if(LookAhead(input, "inf"))
	{
		t->symbol.code = INF;
	}
	else if(LookAhead(input, "larr"))
	{
		t->symbol.code = LARR;
	}
	else if(LookAhead(input, "rarr"))
	{
		t->symbol.code = RARR;
	}
	else if(LookAhead(input, "vec"))
	{
		MarkupCharToken(VECTOR, t);
	}
	else if(LookAhead(input, "sqrt"))
	{
		MarkupCharToken(SQRT, t);
	}
	else if(LookAhead(input, "frac"))
	{
		MarkupCharToken(FRACTION, t);
	}
	else if(LookAhead(input, "nsum"))
	{
		MarkupCharToken(NSUM, t);
	}
	else if(LookAhead(input, "nprod"))
	{
		MarkupCharToken(NPRODUCT, t);
	}
	else if(LookAhead(input, "alpha"))
	{
		t->symbol.code = ALPHA;
	}
	else if(LookAhead(input, "beta"))
	{
		t->symbol.code = BETA;
	}
	else if(LookAhead(input, "gamma"))
	{
		t->symbol.code = GAMMA;
	}
	else if(LookAhead(input, "delta"))
	{
		t->symbol.code = DELTA;
	}
	else if(LookAhead(input, "epsilon"))
	{
		t->symbol.code = EPSILON;
	}
	else if(LookAhead(input, "zeta"))
	{
		t->symbol.code = ZETA;
	}
	else if(LookAhead(input, "eta"))
	{
		t->symbol.code = ETA;
	}
	else if(LookAhead(input, "theta"))
	{
		t->symbol.code = THETA;
	}
	else if(LookAhead(input, "iota"))
	{
		t->symbol.code = IOTA;
	}
	else if(LookAhead(input, "kappa"))
	{
		t->symbol.code = KAPPA;
	}
	else if(LookAhead(input, "lambda"))
	{
		t->symbol.code = LAMBDA;
	}
	else if(LookAhead(input, "mu"))
	{
		t->symbol.code = MU;
	}
	else if(LookAhead(input, "nu"))
	{
		t->symbol.code = NU;
	}
	else if(LookAhead(input, "xi"))
	{
		t->symbol.code = XI;
	}
	else if(LookAhead(input, "omicron"))
	{
		t->symbol.code = OMICRON;
	}
	else if(LookAhead(input, "pi"))
	{
		t->symbol.code = PI;
	}
	else if(LookAhead(input, "rho"))
	{
		t->symbol.code = RHO;
	}
	else if(LookAhead(input, "sigma"))
	{
		t->symbol.code = SIGMA;
	}
	else if(LookAhead(input, "tau"))
	{
		t->symbol.code = TAU;
	}
	else if(LookAhead(input, "upsilon"))
	{
		t->symbol.code = UPSILON;
	}
	else if(LookAhead(input, "phi"))
	{
		t->symbol.code = PHI;
	}
	else if(LookAhead(input, "chi"))
	{
		t->symbol.code = CHI;
	}
	else if(LookAhead(input, "psi"))
	{
		t->symbol.code = PSI;
	}
	else if(LookAhead(input, "omega"))
	{
		t->symbol.code = OMEGA;
	}
	else if(LookAhead(input, "Alpha"))
	{
		t->symbol.code = ALPHA_UPPER;
	}
	else if(LookAhead(input, "Beta"))
	{
		t->symbol.code = BETA_UPPER;
	}
	else if(LookAhead(input, "Gamma"))
	{
		t->symbol.code = GAMMA_UPPER;
	}
	else if(LookAhead(input, "Delta"))
	{
		t->symbol.code = DELTA_UPPER;
	}
	else if(LookAhead(input, "Epsilon"))
	{
		t->symbol.code = EPSILON_UPPER;
	}
	else if(LookAhead(input, "Zeta"))
	{
		t->symbol.code = ZETA_UPPER;
	}
	else if(LookAhead(input, "Eta"))
	{
		t->symbol.code = ETA_UPPER;
	}
	else if(LookAhead(input, "Theta"))
	{
		t->symbol.code = THETA_UPPER;
	}
	else if(LookAhead(input, "Iota"))
	{
		t->symbol.code = IOTA_UPPER;
	}
	else if(LookAhead(input, "Kappa"))
	{
		t->symbol.code = KAPPA_UPPER;
	}
	else if(LookAhead(input, "Lambda"))
	{
		t->symbol.code = LAMBDA_UPPER;
	}
	else if(LookAhead(input, "Mu"))
	{
		t->symbol.code = MU_UPPER;
	}
	else if(LookAhead(input, "Nu"))
	{
		t->symbol.code = NU_UPPER;
	}
	else if(LookAhead(input, "Xi"))
	{
		t->symbol.code = XI_UPPER;
	}
	else if(LookAhead(input, "Omicron"))
	{
		t->symbol.code = OMICRON_UPPER;
	}
	else if(LookAhead(input, "Pi"))
	{
		t->symbol.code = PI_UPPER;
	}
	else if(LookAhead(input, "Rho"))
	{
		t->symbol.code = RHO_UPPER;
	}
	else if(LookAhead(input, "Sigma"))
	{
		t->symbol.code = SIGMA_UPPER;
	}
	else if(LookAhead(input, "Tau"))
	{
		t->symbol.code = TAU_UPPER;
	}
	else if(LookAhead(input, "Upsilon"))
	{
		t->symbol.code = UPSILON_UPPER;
	}
	else if(LookAhead(input, "Phi"))
	{
		t->symbol.code = PHI_UPPER;
	}
	else if(LookAhead(input, "Chi"))
	{
		t->symbol.code = CHI_UPPER;
	}
	else if(LookAhead(input, "Psi"))
	{
		t->symbol.code = PSI_UPPER;
	}
	else if(LookAhead(input, "Omega"))
	{
		t->symbol.code = OMEGA_UPPER;
	}
	else if(LookAhead(input, "thin"))
	{
		t->symbol.code = THINSPACE;
	}
	else if(LookAhead(input, "b"))
	{
		MarkupCharToken(BOLD, t);
	}
	else if(LookAhead(input, "i"))
	{
		MarkupCharToken(ITALIC, t);
	}
	else if(LookAhead(input, "u"))
	{
		MarkupCharToken(UNDERLINE, t);
	}
	else if(LookAhead(input, "r"))
	{
		MarkupCharToken(REGULAR, t);
	}
	else
	{
		t->type = ESC;
		t->c =  getc(input);
	}
}

void GetNextTokenInHTMLMode(FILE* input, token* t)
{
	char c = Peek(input);
	if(c==EOF)
	{
		t->type = ENDF;
		return;
	}
	if(c == '[')
	{
		t->type = MARKUP;
		if(LookAhead(input, "[/html]"))
		{
			t->markup.type = CODE_INLINE_STOP;
			mode = MODE_TEXT;
		}
		else
		{
			CharacterToken(input, t);
		}
	}
	else
	{
		CharacterToken(input, t);
	}
}

void GetNextTokenInCodeMode(FILE* input, token* t)
{
	char c = Peek(input);
	if(c==EOF)
	{
		t->type = ENDF;
		return;
	}
	if(c == '[')
	{
		t->type = MARKUP;
		if(LookAhead(input, "[/c]"))
		{
			t->markup.type = CODE_INLINE_STOP;
			mode = MODE_TEXT;
		}
		else if(LookAhead(input, "[/code]"))
		{
			t->markup.type = CODE_BLOCK_STOP;
			mode = MODE_TEXT;
		}
		else
		{
			CharacterToken(input, t);
		}
	}
	else
	{
		CharacterToken(input, t);
	}
}

void GetNextTokenInMathsMode(FILE* input, token* t)
{
	char c = Peek(input);
	if(c==EOF)
	{
		t->type = ENDF;
		return;
	}
	switch(c)
	{
		case ':':
			getc(input);
			MarkupCharToken(BOLD, t);
			break;
		case '*':
			getc(input);
			SymbolToken(MULTIPLY, t);
			break;
		case '-':
			getc(input);
			SymbolToken(SUBSTRACT, t);
			break;
		case '_':
			getc(input);
			MarkupCharToken(SUBSCRIPT, t);
			break;
		case '^':
			getc(input);
			MarkupCharToken(SUPERSCRIPT, t);
			break;
		case '\n':
			EndlToken(input, t);
			break;
		case '[':
			BlockToken(input, t);
			break;
		case '<':
			getc(input);
			c = Peek(input);
			if(c == '=')
			{
				getc(input);
				SymbolToken(LEQ, t);
			}
			else
			{
				ungetc('<', input);
				LessToken(input, t);
			}
			break;
		case '>':
			getc(input);
			c = Peek(input);
			if(c == '=')
			{
				getc(input);
				SymbolToken(GEQ, t);
			}
			else
			{
				ungetc('>', input);
				CharacterToken(input, t);
			}
			break;
		case '\\':
			EscapeToken(input, t);
			break;
		default:
			CharacterToken(input, t);
			break;
	}
}

void RepeatableHyphen(FILE* input, token* t)
{
	char c;
	int count = 1;
	while((c = getc(input)) == '-')
	{
		count++;
	}

	t->type = SYMBOL;
	if(c == '>')
	{
		t->symbol.code = RARR;
	}
	else
	{
		if(count <= 3)
		{
			t->symbol.code = EMDASH;
		}
		else
		{
			t->symbol.code = LINE;
		}
		ungetc(c, input);
	}
}

void LookAheadForList(FILE* input, token* t)
{
	char buffer[8];
	bool plain = false;
	int count = 0;
	while(count < 8)
	{
		char c = getc(input);
		buffer[count] = c;
		count++;

		if(c == '-')
		{
			if(LookAhead(input, " "))
			{
				t->type = MARKUP;
				t->markup.type = LIST;
				t->markup.value = count;
				return;
			}
			else if(count==1 && LookAhead(input, "-"))
			{
				RepeatableHyphen(input, t);
				return;
			}
			break;
		}
		else if(c != '\t')
		{
			break;
		}
	}

	for(int i=count-1;i>0;i--)
	{
		ungetc(buffer[i], input);
	}
	t->type = CHAR;
	t->c = buffer[0];
}

void GetNextTokenInTextMode(FILE* input, token* t)
{
	char c = Peek(input);
	if(c==EOF)
	{
		t->type = ENDF;
		return;
	}
	switch(c)
	{
		case '=':
			RepeatableMarkupToken(input, '=', SECTION, t);
			break;
		case '\t': case '-':
			LookAheadForList(input, t);
			break;
		case '_':
			getc(input);
			MarkupCharToken(UNDERLINE, t);
			break;
		case '*':
			getc(input);
			MarkupCharToken(BOLD, t);
			break;
		case '/':
			getc(input);
			MarkupCharToken(ITALIC, t);
			break;
		case '\n':
			EndlToken(input, t);
			break;
		case '[':
			BlockToken(input, t);
			break;
		case '<':
			LessToken(input, t);
			break;
		case '\\':
			return EscapeToken(input, t);
		default:
			CharacterToken(input, t);
			break;
	}
}

void GetNextToken(FILE* input, token* t)
{
	//NOTE(martin): finds the next token from input, effectively consumming characters
	//		if no token is found, those 'lookahead' characters are pushed back to the stream

	switch(mode)
	{
		case MODE_HTML:
			return(GetNextTokenInHTMLMode(input, t));

		case MODE_CODE_INLINE: case MODE_CODE_BLOCK:
			return(GetNextTokenInCodeMode(input, t));

		case MODE_MATHS_INLINE: case MODE_MATHS_BLOCK:
			return(GetNextTokenInMathsMode(input, t));

		case MODE_TEXT: default:
			GetNextTokenInTextMode(input, t);
	}
}

void ResetScanMode()
{
	mode = MODE_TEXT;
}