#ifndef WYRM_SIEVE_H
#define WYRM_SIEVE_H

	//	wyrm-sieve.dna - Copyright (C) 2004 wyrmwif@bigfoot.com.  All rights reserved.

	#include "wyrmwif.h"
	int Wyrmsieve_Init(Intr intr);
	int Wyrmsieve_SafeInit(Intr intr);

#endif

		

static const char COPYRIGHT[] = "wyrm-sieve.dna - Copyright (C) 2004 SM Ryan.  All rights reserved.";

#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include "wyrm-sieve.h"
#include "wyrm-io.h"

static char *number(int n) {
	char b[50],*c;
	sprintf(b,"%d",n);
	c = nheap(strlen(b)+1,char);
	strcpy(c,b);
	return c;
}

static char *increment(char *n) {
	char *digit = n+strlen(n); int carry = 1;
	while (carry) {
		if (digit==n) {
			char *n1 = nheap(1+strlen(n)+1,char);
			*n1 = '1'; strcpy(n1+1,n);
			carry = 0;
			dispose(n); n = n1;
		}else if (*--digit=='9') {
			*digit = '0';
			carry = 1;
		}else {
			*digit += 1;
			carry = 0;
		}
	}
	return n;
}

static int decrement(Intr intr,char *n) {
	char *digit = n+strlen(n); int borrow = 1;
	int zero = 1;
	while (borrow) {
		if (digit==n) {
			rprintf(intr,"Attempted to decrement zero."); return TCL_ERROR;
		}else if (*--digit=='0') {
			*digit = '9';
			borrow = 1;
		}else {
			*digit -= 1;
			borrow = 0;
		}
	}
	while (*n && zero) zero = *n++=='0';
	return zero ? TCL_BREAK : TCL_CONTINUE;
}

static char *readline(Tcl_Channel A) {
	char *buffer = 0; int n = 0,m = 0,ch;
	for (;;) {
		int ch = cgetc(A);
		switch (ch) {
			case EOF: case ERR: if (buffer==0) return 0;
			case '\n': ch = 0;
		}
		if (n+1>=m) {m = 2*(n+1); buffer = reheap(m,char,buffer);}
		buffer[n++] = ch;
		if (!ch) break;
	}
	return buffer;
}

static void writeline(Tcl_Channel B,char *n) {
	cputs(B,n); cputc(B,'\n');
}

static int sieveStep(Intr intr,Tcl_Channel A,Tcl_Channel B) {
	int isprime = 1;
	while (1) {
		char *prime = readline(A);
		char *counter = readline(A);
		if (!prime) break;
		if (prime && !counter) return -1;
		writeline(B,prime);
		switch (decrement(intr,counter)) {
			case TCL_BREAK:
				writeline(B,prime);
				isprime = 0;
				break;
			case TCL_CONTINUE:
				writeline(B,counter);
				break;
			default:
				dispose(prime); dispose(counter);
				return TCL_ERROR;
		}
		dispose(prime); dispose(counter);
	}
	return isprime ? TCL_BREAK : TCL_CONTINUE;
}

static void addPrime(char *current,Tcl_Channel PR,Tcl_Channel B) {
	if (PR) writeline(PR,current);
	writeline(B,current);
	writeline(B,current);
}

static int sieveCommand(ClientData clientData,Intr intr,int N,Tcl_Obj *const P[]) {
	chars limit = 0; bool restart = false; int rc;
	Tcl_Channel A = 0,B = 0,PR = chstdout;
	Obj tmp = 0;
	Obj Apath = incr(Tcl_NewStringObj("A.sve",-1));
	Obj Bpath = incr(Tcl_NewStringObj("B.sve",-1));
	chars current = 0;
	while (++P,--N>0) {
		chars p = Tcl_GetString(*P);
		if (isdigit(p[0])) {
			limit = p;
			limit = strcpy(nheap(strlen(limit)+1,char),limit);
		}else if (strbegins("-t",p) && N>0) {
			tmp = P[1]; P++,N--;
		}else if (strbegins("-o",p) && N>0) {
			chars pr = Tcl_GetString(P[1]); P++,N--;
			if (streq(pr,"none")) {
				PR = 0;
			}else {
				int mood; PR = Tcl_GetChannel(intr,pr,&mood);
				if (!PR) {
					rprintf(intr,"not a channel: %{y}s",pr);
					goto error;
				}
				if (!(TCL_WRITABLE&mood)) {
					rprintf(intr,"not a writable channel: %{y}s",pr);
					goto error;
				}
			}
		}else {
			rprintf(intr,"unrecognised option: %s",p);
			return TCL_ERROR;
		}
	}
	if (tmp) {
		Obj L,E[2];
		E[0] = tmp; E[1] = Apath; L = incr(Tcl_NewListObj(2,E)); decr(Apath);
		Apath = incr(Tcl_FSJoinPath(L,-1)); decr(L);
		E[0] = tmp; E[1] = Bpath; L = incr(Tcl_NewListObj(2,E)); decr(Bpath);
		Bpath = incr(Tcl_FSJoinPath(L,-1)); decr(L);
	}
	
	if (Tcl_FSAccess(Apath,0)<0 ||Tcl_FSAccess(Bpath,0)==0) {
		Tcl_FSRenameFile(Bpath,Apath);
	}
	A = Tcl_FSOpenFileChannel(intr,Apath,"r",0);
	if (A) {
		current = readline(A);
		if (current && limit) {
			chars t = strcpy(nheap(strlen(limit)+1,char),limit);
			current = increment(current);
			for (restart=true; restart; ) {
				char *prime = readline(A);
				char *counter = readline(A);
				if (!prime) break;
				dispose(prime);
				if (prime && !counter) restart = false;
				dispose(counter);
				switch (decrement(intr,t)) {
					case TCL_BREAK: restart = false;
					case TCL_CONTINUE: break;
					case TCL_ERROR: dispose(t);
					goto error;
				}
			}
			if (restart) {dispose(limit); limit = t;}
			else {dispose(t);}
		}else {
			restart = true;
		}
		if (!restart) dispose(current);
		Tcl_Close(intr,A); A = 0;
	}
	if (!restart) {
		Tcl_ResetResult(intr);
		A = Tcl_FSOpenFileChannel(intr,Apath,"w",0600);
		if (!A) {
			dispose(current); dispose(limit);
			return TCL_ERROR;
		}
		current = number(2);
		writeline(A,current);
		Tcl_Close(intr,A); A = 0;
	}
	while (1) {
		A = Tcl_FSOpenFileChannel(intr,Apath,"r",0); if (!A) goto error;
		B = Tcl_FSOpenFileChannel(intr,Bpath,"w",0600); if (!B) goto error;
		dispose(readline(A)); writeline(B,current);
		switch (sieveStep(intr,A,B)) {
			case TCL_BREAK:
				Tcl_SetResult(intr,current,TCL_VOLATILE);
				addPrime(current,PR,B);
				if (limit) {
					switch (decrement(intr,limit)) {
						case TCL_BREAK: goto okay;
						case TCL_ERROR: 
						goto error;
					}
				}
				break;
			case TCL_ERROR: 
			goto error;
		}
		current = increment(current);
		Tcl_Close(intr,A); A = 0;
		Tcl_Close(intr,B); B = 0;
		if (Tcl_FSDeleteFile(Apath)<0) {
			rprintf(intr,"failed to delete %{y}s",Apath);
			goto error;
		}
		if (Tcl_FSRenameFile(Bpath,Apath)<0) {
			rprintf(intr,"failed to rename %{y}s to %{y}s",Bpath,Apath);
			goto error;
		}
	}
okay:
	rc = TCL_OK;
exit:
	if (A) Tcl_Close(intr,A);
	if (B) Tcl_Close(intr,B);
	dispose(current); dispose(limit);
	decr(Apath); decr(Bpath);
	return rc;
error:
	rc = TCL_ERROR;
	goto exit;
}

int Wyrmsieve_Init(Intr intr) {
	Tcl_PkgProvide(intr,"wyrmsieve",VERSION);
	Tcl_PkgRequire(intr,"wyrmwif","1",0);
	Tcl_CreateObjCommand(intr,"::wyrm::sieve",sieveCommand,0,0);
	return Tcl_VarEval(intr,
			"namespace eval ::wyrm {namespace export sieve}\n",
			0);
}

int Wyrmsieve_SafeInit(Intr intr) {
	return rprintf(intr,"%!package not available in a safe interpretter",TCL_ERROR);
}