/** \file tokenizer.c

    A specialized tokenizer for tokenizing the fish language. In the
    future, the tokenizer should be extended to support marks,
    tokenizing multiple strings and disposing of unused string
    segments.
*/

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <wchar.h>
#include <wctype.h>
#include <string.h>
#include <unistd.h>

#include "util.h"
#include "wutil.h"
#include "tokenizer.h"
#include "common.h"
#include "wildcard.h"

/**
   Error string for unexpected end of string
*/
#define EOL_ERROR L"Unexpected end of token"
/**
   Error string for mismatched parenthesis
*/
#define PARAN_ERROR L"Parenthesis mismatch"
/**
   Error string for invalid redirections
*/
#define REDIRECT_ERROR L"Invalid redirection"
/**
   Error string for invalid input
*/
#define INPUT_ERROR L"Invalid input"

/**
   Error string for when trying to pipe from fd 0
*/
#define PIPE_ERROR L"Can not use fd 0 as pipe output"

/**
  Characters that separate tokens. They are ordered by frequency of occurrence to increase parsing speed.
*/
#define SEP L" \n|\t;#\r<>^&"
/**
   Tests if the tokenizer buffer is large enough to hold contents of
   the specified length, and if not, reallocates the tokenizer buffer.

   \return 0 if the system could not provide the memory needed, and 1 otherwise.
*/

/**
   Maximum length of a string containing a file descriptor number
*/
#define FD_STR_MAX_LEN 16

const static wchar_t *tok_desc[] =
{
	L"Tokenizer not yet initialized",
	L"Tokenizer error",
	L"Invalid token",
	L"String",
	L"Pipe",
	L"End of command",
	L"Redirect output to file",
	L"Append output to file",
	L"Redirect input to file",
	L"Redirect to file descriptor",
	L"Run job in background",
	L"Comment"
}
;

/**
   Make sure the tokenizer buffer have room for a token of the specified size.
*/
static int check_size( tokenizer *tok, size_t len )
{
	if( tok->last_len <= len )
	{
		wchar_t *tmp;
		tok->last_len = len +1;
		tmp = realloc( tok->last, sizeof(wchar_t)*tok->last_len );
		if( tmp == 0 )
		{
			wperror( L"realloc" );
			return 0;
		}
		tok->last = tmp;
	}
	return 1;
}

/**
   Set the latest tokens string to be the specified error message
*/
static void tok_error( tokenizer *tok, const wchar_t *err )
{
	tok->last_type = TOK_ERROR;
	if( !check_size( tok, wcslen( err)+1 ))
	{
		if( tok->last != 0 )
			*tok->last=0;
		return;
	}

	wcscpy( tok->last, err );
}

void tok_init( tokenizer *tok, const wchar_t *b, int flags )
{
//	fwprintf( stderr, L"CREATE: \'%ls\'\n", b );
		

	memset( tok, 0, sizeof( tokenizer) );
	
	tok ->last = 0;
	tok ->last_len = 0;
	tok->accept_unfinished = flags & TOK_ACCEPT_UNFINISHED;
	tok->show_comments = flags & TOK_SHOW_COMMENTS;
	tok->has_next=1;
	

	/* 
	   Before we copy the buffer we need to check that it is not
	   null. But before that, we need to init the tokenizer far enough
	   so that errors can be properly flagged
	*/
	if( !b )
	{
		tok_error( tok, INPUT_ERROR );
		return;
	}

	tok->has_next = (*b != L'\0');
	tok->orig_buff = tok->buff = /*wcsdup*/(b);

	if( !tok->orig_buff )
	{
		die_mem();
		
	}
	
	if( tok->accept_unfinished )
	{
		int l = wcslen( tok->orig_buff );
		if( l != 0 )
		{
			if( tok->orig_buff[l-1] == L'\\' )
				tok->orig_buff[l-1] = L'\0';
		}
	}

	tok_next( tok );

}

void tok_destroy( tokenizer *tok )
{
	free( tok->last );
//	free( tok->orig_buff );
}

int tok_last_type( tokenizer *tok )
{
	return tok->last_type;
}

wchar_t *tok_last( tokenizer *tok )
{
	return tok->last;
}

int tok_has_next( tokenizer *tok )
{
/*	fwprintf( stderr, L"has_next is %ls \n", tok->has_next?L"true":L"false" );*/
	return 	tok->has_next;
}

/**
   Tests if this character can be a part of a string
*/

static int is_string_char( wchar_t c )
{
	if( !c ||  wcschr( SEP, c ) )
	{
		return 0;
	}
	return 1;
}

/**
   Quick test to catch the most common 'non-magical' characters, makes
   read_string slightly faster by adding a fast path for the most
   common characters. This is obviously not a suitable replacement for
   iswalpha.
*/
static int myal( wchar_t c )
{
	return (c>=L'a' && c<=L'z') || (c>=L'A'&&c<=L'Z');
}

/**
   Read the next token as a string
*/
static void read_string( tokenizer *tok )
{
	const wchar_t *start;
	int len;
	int mode=0;
	wchar_t prev;
	int do_loop=1;
	int paran_count=0;

	start = tok->buff;

	while( 1 )
	{
		
		if( !myal( *tok->buff ) )
		{
//			debug(1, L"%lc", *tok->buff );

		if( *tok->buff == L'\\' )
		{
			tok->buff++;
			if( *tok->buff == L'\0' )
			{
				tok_error( tok, EOL_ERROR );
				return;
			}
			tok->buff++;
			continue;
		}

		/*
		  The modes are as follows:

		  0: regular text
		  1: inside of subshell
		  2: inside of array brackets
		  3: inside of array brackets and subshell, like in '$foo[(ech'
		*/
		switch( mode )
		{
			case 0:
			{
				switch( *tok->buff )
				{
					case L'(':
					{
						paran_count=1;
						mode = 1;
						break;
					}
					
					case L'[':
					{
						if( tok->buff != start )
							mode=2;
						break;
					}

					case L'\'':
					case L'"':
					{
						
						wchar_t *end = quote_end( tok->buff );
						tok->last_quote = *tok->buff;
						if( end )
						{
							tok->buff=end;
						}
						else
						{
							tok->buff += wcslen( tok->buff );
							
							if( (!tok->accept_unfinished) )
							{
								tok_error( tok, EOL_ERROR );
								return;
							}
							do_loop = 0;
							
						}
						break;
					}

					default:
					{
						if( !is_string_char(*(tok->buff)) )
						{
							do_loop=0;
						}
					}
				}
				break;
			}
		
			case 3:
			case 1:
				switch( *tok->buff )
				{
					case L'\'':
					case L'\"':
					{
						wchar_t *end = quote_end( tok->buff );
						if( end )
						{
							tok->buff=end;
						}
						else
							do_loop = 0;
						break;
					}

					case L'(':
						paran_count++;
						break;
					case L')':
						paran_count--;
						if( paran_count == 0 )
						{
							mode--;
						}
						break;
					case L'\0':
						do_loop = 0;
						break;
				}
				break;
			case 2:
				switch( *tok->buff )
				{
					case L'(':
						paran_count=1;
						mode = 3;
						break;

					case L']':
						mode=0;
						break;

					case L'\0':
						do_loop = 0;
						break;
				}
				break;
		}
		}
		

		if( !do_loop )
			break;

		prev = *tok->buff;
		tok->buff++;
	}

	if( (!tok->accept_unfinished) && (mode!=0) )
	{
		tok_error( tok, PARAN_ERROR );
		return;
	}


	len = tok->buff - start;

	if( !check_size( tok, len ))
		return;

	memcpy( tok->last, start, sizeof(wchar_t)*len );
	tok->last[len] = L'\0';
	tok->last_type = TOK_STRING;
}

/**
   Read the next token as a comment.
*/
static void read_comment( tokenizer *tok )
{
	const wchar_t *start;
	int len;

	start = tok->buff;
	while( *(tok->buff)!= L'\n' && *(tok->buff)!= L'\0' )
		tok->buff++;

	len = tok->buff - start;
	if( !check_size( tok, len ))
		return;

	memcpy( tok->last, start, sizeof(wchar_t)*len );
	tok->last[len] = L'\0';
	tok->last_type = TOK_COMMENT;
}

/**
   Read a FD redirect.
*/
static void read_redirect( tokenizer *tok, int fd )
{
	int mode = -1;
	
	if( (*tok->buff == L'>') ||
		(*tok->buff == L'^') )
	{
		tok->buff++;
		if( *tok->buff == *(tok->buff-1) )
		{
			tok->buff++;
			mode = 1;
		}
		else
		{
			mode = 0;
		}

		if( *tok->buff == L'|' )
		{
			if( fd == 0 )
			{
				tok_error( tok, PIPE_ERROR );
				return;
			}
			check_size( tok, FD_STR_MAX_LEN );						
			tok->buff++;
			swprintf( tok->last, FD_STR_MAX_LEN, L"%d", fd );
			tok->last_type = TOK_PIPE;
			return;
		}
	}
	else if( *tok->buff == L'<' )
	{
		tok->buff++;
		mode = 2;
	}
	else
	{
		tok_error( tok, REDIRECT_ERROR);
	}
	
	if( !check_size( tok, 2 ))
	{
		return;
	}
	
	swprintf( tok->last, tok->last_len, L"%d", fd );
	
	if( *tok->buff == L'&' )
	{
		tok->buff++;
		tok->last_type = TOK_REDIRECT_FD;
	}
	else
	{
		tok->last_type = TOK_REDIRECT_OUT + mode;
	}
}

wchar_t tok_last_quote( tokenizer *tok )
{
	return tok->last_quote;
}

/**
   Test if a character is whitespace. Differs from iswspace in that it
   does not consider a newline to be whitespace.
*/
static int my_iswspace( wchar_t c )
{
	if( c == L'\n' )
		return 0;
	else
		return iswspace( c );
}


const wchar_t *tok_get_desc( int type )
{
	return tok_desc[type];
}


void tok_next( tokenizer *tok )
{
//	fwprintf( stderr, L"tok_next on %ls (prev=%ls)\n", tok->orig_buff, tok_desc[tok->last_type] );

	if( tok_last_type( tok ) == TOK_ERROR )
	{
		tok->has_next=0;	
		return;	
	}
	
	if( !tok->has_next )
	{
/*		wprintf( L"EOL\n" );*/
		tok->last_type = TOK_END;
		return;
	}

	while( my_iswspace(*(tok->buff) ) )
		tok->buff++;

	if( *tok->buff == L'#')
	{
		if( tok->show_comments )
		{
			tok->last_pos = tok->buff - tok->orig_buff;
			read_comment( tok );
			return;
		}
		else
		{
			while( *(tok->buff)!= L'\n' && *(tok->buff)!= L'\0' )
				tok->buff++;
		}

		while( my_iswspace(*(tok->buff) ) )
			tok->buff++;
	}

	tok->last_pos = tok->buff - tok->orig_buff;

	switch( *tok->buff )
	{

		case L'\0':
			tok->last_type = TOK_END;
			/*fwprintf( stderr, L"End of string\n" );*/
			tok->has_next = 0;
			break;
		case 13:
		case L'\n':
		case L';':
			tok->last_type = TOK_END;
			tok->buff++;
			break;
		case L'&':
			tok->last_type = TOK_BACKGROUND;
			tok->buff++;
			break;

		case L'|':
			check_size( tok, 2 );
			
			tok->last[0]=L'1';
			tok->last[1]=L'\0';			
			tok->last_type = TOK_PIPE;
			tok->buff++;
			break;

		case L'>':
			return read_redirect( tok, 1 );
		case L'<':
			return read_redirect( tok, 0 );
		case L'^':
			return read_redirect( tok, 2 );

		default:
		{
			
			if( iswdigit( *tok->buff ) )
			{				
				wchar_t *orig = tok->buff;
				int fd = 0;
				while( iswdigit( *tok->buff ) )
					fd = (fd*10) + (*(tok->buff++) - L'0');

				switch( *(tok->buff))
				{
					case L'^':
					case L'>':
					case L'<':
						read_redirect( tok, fd );
						return;
				}
				tok->buff = orig;				
			}
			read_string( tok );
		}
		
	}

}

wchar_t *tok_string( tokenizer *tok )
{
	return tok->orig_buff;
}

wchar_t *tok_first( const wchar_t *str )
{
	tokenizer t;
	wchar_t *res=0;

	tok_init( &t, str, 0 );
	
	switch( tok_last_type( &t ) )
	{
		case TOK_STRING:
//				fwprintf( stderr, L"Got token %ls\n", tok_last( &t ));
			res = wcsdup(tok_last( &t ));
			break;
		default:
			break;
	}

	tok_destroy( &t );
	return res;
}


int tok_get_pos( tokenizer *tok )
{
	return tok->last_pos;
}


void tok_set_pos( tokenizer *tok, int pos )
{
	tok->buff = tok->orig_buff + pos;
	tok->has_next = 1;
	tok_next( tok );
}


#ifdef TOKENIZER_TEST

/**
   This main function is used for compiling the tokenizer_test command, used for testing the tokenizer.
*/
int main( int argc, char **argv )
{
	tokenizer tok;
	int i;
	for ( i=1; i<argc; i++ )
	{
		wprintf( L"Tokenizing string %s\n", argv[i] );
		for( tok_init( &tok, str2wcs(argv[i]), 0 ); tok_has_next( &tok ); tok_next( &tok ) )
		{
			switch( tok_last_type( &tok ) )
 			{
				case TOK_INVALID:
					wprintf( L"Type: INVALID\n" );
					break;
				case TOK_STRING:
					wprintf( L"Type: STRING\t Value: %ls\n", tok_last( &tok ) );
					break;
				case TOK_PIPE:
					wprintf( L"Type: PIPE\n" );
					break;
				case TOK_END:
					wprintf( L"Type: END\n" );
					break;
				case TOK_ERROR:
					wprintf( L"Type: ERROR\n" );
					break;
				default:
					wprintf( L"Type: Unknown\n"  );
					break;
			}
		}
		tok_destroy( &tok );

	}
}

#endif