/* ical.l */

/* disable unused functions so we don't
   get compiler warnings about them */

%option noyywrap nounput noinput

/* change our prefix from yy to ical */

%option prefix="ical"

/* use the pure parser calling convention */

%option reentrant bison-bridge bison-locations

%{
#include "ical.tab.h"

#define YY_EXIT_FAILURE ((void)yyscanner, EXIT_FAILURE)

/* XOPEN for strdup */
#define _XOPEN_SOURCE 600
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

/* seems like a bug that I have to do this, since flex
   should know prefix=ical and match bison's ICALSTYPE */
#define YYSTYPE ICALSTYPE
#define YYLTYPE ICALLTYPE

/* Helper function to convert string to uppercase for case-insensitive matching */
static char *str_toupper(const char *str) {
    char *result = strdup(str);
    if (!result) return NULL;
    for (int i = 0; result[i]; i++) {
        result[i] = toupper(result[i]);
    }
    return result;
}

%}

/* Lexer states for RFC 5545 content line parsing */
%x PARAM_STATE VALUE_STATE COMPONENT_STATE

/* Define patterns for RFC 5545 tokens */
ALPHA           [A-Za-z]
DIGIT           [0-9]
CRLF            \r?\n
WSP             [ \t]
IANA_TOKEN      ({ALPHA}|{DIGIT}|"-")+
X_NAME          "X-"[A-Za-z0-9-]*"-"?{IANA_TOKEN}
SAFE_CHAR       [ !#-+\--9<-~]
VALUE_CHAR      [ !-~]

%%

    /* Line folding - continuation lines start with whitespace (all states) */
<*>{CRLF}{WSP}+ {
    /* Update location - treat folded line as continuation */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_line++;
    yylloc->last_column = yyleng;
    
    /* Folded lines are treated as a single space */
    yylval->str = strdup(" ");
    return FOLDING_WS;
}

    /* INITIAL state: expecting property name at start of content line */

    /* Component BEGIN/END keywords - case insensitive */
(?i:"BEGIN") {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    /* After BEGIN, we expect a component name */
    BEGIN(COMPONENT_STATE);
    return BEGIN_TOKEN;
}

(?i:"END") {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    /* After END, we expect a component name */
    BEGIN(COMPONENT_STATE);
    return END_TOKEN;
}

    /* Component names - case insensitive */
(?i:"VCALENDAR") {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    yylval->str = str_toupper(yytext);
    return COMPONENT_NAME;
}

(?i:"VEVENT") {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    yylval->str = str_toupper(yytext);
    return COMPONENT_NAME;
}

(?i:"VTODO") {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    yylval->str = str_toupper(yytext);
    return COMPONENT_NAME;
}

(?i:"VJOURNAL") {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    yylval->str = str_toupper(yytext);
    return COMPONENT_NAME;
}

(?i:"VFREEBUSY") {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    yylval->str = str_toupper(yytext);
    return COMPONENT_NAME;
}

(?i:"VTIMEZONE") {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    yylval->str = str_toupper(yytext);
    return COMPONENT_NAME;
}

(?i:"VALARM") {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    yylval->str = str_toupper(yytext);
    return COMPONENT_NAME;
}

    /* Property names - only in INITIAL state at start of content line */
    /* X_NAME must come before IANA_TOKEN since it's more specific */
{X_NAME} {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    yylval->str = str_toupper(yytext);
    return PROPERTY_NAME;
}

{IANA_TOKEN} {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    yylval->str = str_toupper(yytext);
    return PROPERTY_NAME;
}

    /* Semicolon starts parameter parsing */
";" {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column++;
    
    BEGIN(PARAM_STATE);
    return ';';
}

    /* Colon starts value parsing */
":" {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column++;
    
    BEGIN(VALUE_STATE);
    return ':';
}

    /* PARAM_STATE: parsing parameters between ; and : */
<PARAM_STATE>{
    /* Parameter names - X_NAME must come before IANA_TOKEN */
    {X_NAME} {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = str_toupper(yytext);
        return PROPERTY_NAME;  /* Reuse token for param names */
    }
    
    {IANA_TOKEN} {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = str_toupper(yytext);
        return PROPERTY_NAME;  /* Reuse token for param names */
    }

    /* Quoted parameter values */
    \"([^"]|\\\")*\" {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        /* Remove quotes and handle escaped quotes */
        size_t len = strlen(yytext);
        char *unquoted = malloc(len - 1);
        if (!unquoted) return PARAM_VALUE;
        
        strncpy(unquoted, yytext + 1, len - 2);
        unquoted[len - 2] = '\0';
        
        /* Handle escaped quotes - replace \" with " */
        char *src = unquoted, *dst = unquoted;
        while (*src) {
            if (*src == '\\' && *(src + 1) == '"') {
                *dst++ = '"';
                src += 2;
            } else {
                *dst++ = *src++;
            }
        }
        *dst = '\0';
        
        yylval->str = unquoted;
        return PARAM_VALUE;
    }

    /* Unquoted parameter values - SAFE-CHAR per RFC excluding = ; : , " */
    [ !#-+\--9<>?@A-Z\[\\\]^_`a-z{|}~]+ {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = strdup(yytext);
        return PARAM_VALUE;
    }
    
    "=" {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column++;
        
        return '=';
    }
    
    "," {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column++;
        
        return ',';
    }
    
    ";" {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column++;
        
        return ';';
    }
    
    ":" {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column++;
        
        BEGIN(VALUE_STATE);
        return ':';
    }
}

    /* COMPONENT_STATE: parsing component name after BEGIN: or END: */
<COMPONENT_STATE>{
    ":" {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column++;
        
        /* Stay in COMPONENT_STATE - we expect a component name next */
        return ':';
    }
    
    /* Component names in COMPONENT_STATE */
    (?i:"VCALENDAR") {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = str_toupper(yytext);
        return COMPONENT_NAME;
    }

    (?i:"VEVENT") {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = str_toupper(yytext);
        return COMPONENT_NAME;
    }

    (?i:"VTODO") {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = str_toupper(yytext);
        return COMPONENT_NAME;
    }

    (?i:"VJOURNAL") {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = str_toupper(yytext);
        return COMPONENT_NAME;
    }

    (?i:"VFREEBUSY") {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = str_toupper(yytext);
        return COMPONENT_NAME;
    }

    (?i:"VTIMEZONE") {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = str_toupper(yytext);
        return COMPONENT_NAME;
    }

    (?i:"VALARM") {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = str_toupper(yytext);
        return COMPONENT_NAME;
    }
}

    /* VALUE_STATE: parsing property value after : until CRLF */
<VALUE_STATE>{
    /* Property value - VALUE-CHAR per RFC (any textual character) */
    [ !-~]+ {
        /* Update location */
        yylloc->first_line = yylloc->last_line;
        yylloc->first_column = yylloc->last_column;
        yylloc->last_column += yyleng;
        
        yylval->str = strdup(yytext);
        return PARAM_VALUE;  /* Reuse token for property values */
    }
}

    /* CRLF - end of content line, reset to INITIAL state */
<*>{CRLF} {
    /* Update location - newline resets column and increments line */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_line++;
    yylloc->last_column = 1;
    
    /* Reset to INITIAL state for next content line */
    BEGIN(INITIAL);
    return CRLF;
}

    /* Whitespace within lines - ignore in all states */
<*>{WSP}+ {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column += yyleng;
    
    /* Ignore whitespace within content lines */
}

    /* Everything else */
<*>. {
    /* Update location */
    yylloc->first_line = yylloc->last_line;
    yylloc->first_column = yylloc->last_column;
    yylloc->last_column++;
    
    return *yytext;
}

%%