#include "rc.h"

#define	onebyte(c)	     ((c&0x80)==0x00)
#define	twobyte(c)	     ((c&0xe0)==0xc0)
#define	threebyte(c)	 ((c&0xf0)==0xe0)
#define	fourbyte(c)	     ((c&0xf8)==0xf0)

// -----------------------------------------------------------------------
// globals

static int lastc, nextc=EOF, lastdol, lastword, doprompt = 1;
static char buf[8*1024];

// -----------------------------------------------------------------------
// utilities

static uchar nwordc[256] =
{
	1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

int
wordchr(int c)
{
	return !nwordc[c] && c!=EOF;
}


static uchar nquotec[256] =
{
	1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

int
quotechr(char c)
{
	return !nquotec[c] && c!=EOF;
}

static uchar nvarc[256] =
{
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};


int
varchr(char c)
{
    return !nvarc[c] && c!=EOF;
}

static
void
prompt(void)
{
    shell->cmd.line++;
    doprompt = 0;
}

/* lookahead one byte */
static
int
lookahead(void)
{
    int c;

    if(nextc != EOF)
        return nextc;
    if(shell->cmd.eof)
        return EOF;

    if(doprompt)
        prompt();

    c = rchr(shell->cmd.io);
    doprompt = c == '\n' || c == EOF;

    if(c == EOF)
        shell->cmd.eof++;

    return nextc = c;
}

/* consumes the lookahead */
static
int
advance(void)
{
    int c = lookahead();
    lastc = nextc, nextc = EOF;

    return c;
}

/* 
 * advance until we no longer hit horizontal space 
 * consumes all comments
 */ 
static
void
skipws(void)
{
    int c;
    for(;;) {
        c = lookahead();
        if(c=='#'){
            for(;;){
                c = lookahead();
                if(c=='\n' || c==EOF)
                    break;
                advance();
            }
        }
        if(c==' ' || c=='\t')
            advance();
        else 
            return;
    }
}

/* advance until we no longer hit any space */
void
skipnl(void)
{
    int c;
    for(;;) {
        skipws();
        if ((c = lookahead()) != '\n')
            return;
        advance();
    }
}

/* advance if next char is equal to c */
static
int
nextis(int c)
{
    if(lookahead()==c) {
        advance();
        return 1;
    }
    return 0;
}

/* functions to append to our write buffer */
static
char*
putbyte(char *s, int c)
{
    if(!s)
        return s;
    if(s == arrend(buf)){
        *s = 0;
        rcerror("out of buffer space");
        return nil;
    }
    *s++ = c;
    return s;
}

static
char*
putrune(char *s, int c)
{
    s = putbyte(s, c);
    if (onebyte(c))
        return s;
    if (twobyte(c))
        return putbyte(s, advance());
    if (threebyte(c)) {
        putbyte(s, advance());
        return putbyte(s, advance());
    }
    if (fourbyte(c)) {
        putbyte(s, advance());
        putbyte(s, advance());
        return putbyte(s, advance());
    }
    rcerror("malformed utf8 stream");
    return nil;
}

// -----------------------------------------------------------------------
// main exports

void
rcerror(char *fmt, ...)
{
    va_list args;

    pfmt(errio, "rc:");
    if (shell->cmd.io)
        pfmt(errio, "%s:%d ", shell->cmd.name, shell->cmd.line);

    va_start(args, fmt);
    vpfmt(errio, fmt, args);
    va_end(args);

    pfmt(errio, "\n");

    flush(&errio);
    lastword = lastdol = 0;
    while (lastc != '\n' && lastc != EOF)
        advance();
    /* for debugging only */
    abort();
}

/* word is only modified in the event of a lexed word */
int
lex(Tree **node)
{
    int c;
    char *w = buf;
    /* 
     * NOTE: 
     * we inject tokens into the lexer based on context if last token = word:
     * if we see a (, then we interpret that as a subscript
     * otherwise, if the next character is the first char of a word, we return a ^ operator.
     */ 
    if(lastword){
        lastword=0;
        c = lookahead();
        if(c=='('){
            advance();
            return Tlparen;
        }
        if(quotechr(c))
            return Tcarot;
    }

    skipws();
    switch(c=advance()) {
    case EOF:
        lastdol = 0;
        return EOF;
    case '$':
        lastdol = 1;
        if(nextis('#'))
            return Tcount;
        if (nextis('"'))
            return Tquote;
        return Tdol;
    case '&':
        lastdol = 0;
        if(nextis('&'))
            return Tandand;
        return Tand;

    case '!':
        return Tbang;
    case '@':
        return Tsubshell;
    case '~':
        return Ttwiddle;

    case '|':
        lastdol = 0;
        if(nextis('|')){
            skipnl();
            return Toror;
        }
        (*node) = newtree();
        (*node)->type = Tpipe;
        (*node)->redir.fd[0] = 0;
        (*node)->redir.fd[1] = 1;
        goto redir;
    case '>':
        (*node) = newtree();
        (*node)->type = Tredir;
        if (nextis(c))
            (*node)->redir.type = Rappend;
        else
            (*node)->redir.type = Rwrite;
        (*node)->redir.fd[0] = 1;
        goto redir;
    case '<':
        (*node) = newtree();
        (*node)->type = Tredir;
        if(nextis(c))
            (*node)->redir.type = Rhere;
        else if(nextis('>'))
            (*node)->redir.type = Rrdwr;
        else
            (*node)->redir.type = Rread;
        (*node)->redir.fd[0] = 0;
        /* fallthrough */
    redir:
        if(nextis('[')) {
            c = advance();
            if(c < '0' || '9' < c) {
            redirerr:
                rcerror("incorrect redirection syntax");
                return EOF;
            }
            (*node)->redir.fd[0] = 0;
            do {
                (*node)->redir.fd[0] = 10*(*node)->redir.fd[0]+(c-'0');
                c = advance();
            } while('0'<=c && c<='9');

            if(c == '=') {
                if((*node)->type == Tredir)
                    (*node)->type = Tdup;
                c = advance();
                if('0'<=c && c<='9') {
                    (*node)->redir.type  = Rdupfd;
                    (*node)->redir.fd[1] = (*node)->redir.fd[0];
                    (*node)->redir.fd[0] = 0;
                    do {
                        (*node)->redir.fd[0] = 10*(*node)->redir.fd[0]+(c-'0');
                        c = advance();
                    } while('0'<=c && c<='9');
                } else {
                    if((*node)->type == Tpipe)
                        goto redirerr;
                    (*node)->redir.type = Rclose;
                }
            }
            if (c != ']'
            ||(*node)->type==Tdup && ((*node)->redir.type==Rhere || (*node)->redir.type==Rappend))
                goto redirerr;
        }
        if ((c = ((*node)->type)) == Tpipe)
            skipnl();
        return c;

    case '\'':
        lastdol  = 0;
        lastword = 1;
        for(;;){
            c = advance();
            if(c==EOF)
                break;
            if(c=='\''){
                if(lookahead()!='\'')
                    break;
                advance();
            }
            w = putrune(w, c);
        }
        *w = 0;
        *node = wordnode(buf);
        (*node)->quoted = 1;
        return Tword;
    }
    if (!wordchr(c)) {
        lastdol = 0;
        return c;
    }
    for(;;){
        if(c=='*'||c=='['||c=='?'||c==GLOB)
            w = putbyte(w, GLOB);
        w = putrune(w, c);
        c = lookahead();
        if(lastdol?!varchr(c):!wordchr(c))
            break;
        advance();
    }
    *w = 0;

    if ((c = kwlookup(buf)) == -1) {
        (*node) = wordnode(buf);
        (*node)->type = c = Tword;
        (*node)->quoted   = 0;
        lastword = 1;
    }

    lastdol  = 0;
    return c;
}