#include "git-compat-util.h"

#include "line-range.h"

#include "xdiff-interface.h"

#include "strbuf.h"

#include "userdiff.h"

/*

 * Parse one item in the -L option

 *

 * 'begin' is applicable only to relative range anchors. Absolute anchors

 * ignore this value.

 *

 * When parsing "-L A,B", parse_loc() is called once for A and once for B.

 *

 * When parsing A, 'begin' must be a negative number, the absolute value of

 * which is the line at which relative start-of-range anchors should be

 * based. Beginning of file is represented by -1.

 *

 * When parsing B, 'begin' must be the positive line number immediately

 * following the line computed for 'A'.

 */

static const char *parse_loc(const char *spec, nth_line_fn_t nth_line,

			     void *data, long lines, long begin, long *ret)

{

	char *term;

	const char *line;

	long num;

	int reg_error;

	regex_t regexp;

	regmatch_t match[1];

	/* Allow "-L <something>,+20" to mean starting at <something>

	 * for 20 lines, or "-L <something>,-5" for 5 lines ending at

	 * <something>.

	 */

	if (1 <= begin && (spec[0] == '+' || spec[0] == '-')) {

		num = strtol(spec + 1, &term, 10);

		if (term != spec + 1) {

			if (!ret)

				return term;

			if (num == 0)

				die("-L invalid empty range");

			if (spec[0] == '-')

				num = 0 - num;

			if (0 < num)

				*ret = begin + num - 2;

			else if (!num)

				*ret = begin;

			else

				*ret = begin + num > 0 ? begin + num : 1;

			return term;

		}

		return spec;

	}

	num = strtol(spec, &term, 10);

	if (term != spec) {

		if (ret) {

			if (num <= 0)

				die("-L invalid line number: %ld", num);

			*ret = num;

		}

		return term;

	}

	if (begin < 0) {

		if (spec[0] != '^')

			begin = -begin;

		else {

			begin = 1;

			spec++;

		}

	}

	if (spec[0] != '/')

		return spec;

	/* it could be a regexp of form /.../ */

	for (term = (char *) spec + 1; *term && *term != '/'; term++) {

		if (*term == '\\')

			term++;

	}

	if (*term != '/')

		return spec;

	/* in the scan-only case we are not interested in the regex */

	if (!ret)

		return term+1;

	/* try [spec+1 .. term-1] as regexp */

	*term = 0;

	begin--; /* input is in human terms */

	line = nth_line(data, begin);

	if (!(reg_error = regcomp(&regexp, spec + 1, REG_NEWLINE)) &&

	    !(reg_error = regexec(&regexp, line, 1, match, 0))) {

		const char *cp = line + match[0].rm_so;

		const char *nline;

		while (begin++ < lines) {

			nline = nth_line(data, begin);

			if (line <= cp && cp < nline)

				break;

			line = nline;

		}

		*ret = begin;

		regfree(&regexp);

		*term++ = '/';

		return term;

	}

	else {

		char errbuf[1024];

		regerror(reg_error, &regexp, errbuf, 1024);

		die("-L parameter '%s' starting at line %ld: %s",

		    spec + 1, begin + 1, errbuf);

	}

}

static int match_funcname(xdemitconf_t *xecfg, const char *bol, const char *eol)

{

	if (xecfg) {

		char buf[1];

		return xecfg->find_func(bol, eol - bol, buf, 1,

					xecfg->find_func_priv) >= 0;

	}

	if (bol == eol)

		return 0;

	if (isalpha(*bol) || *bol == '_' || *bol == '$')

		return 1;

	return 0;

}

static const char *find_funcname_matching_regexp(xdemitconf_t *xecfg, const char *start,

						 regex_t *regexp)

{

	int reg_error;

	regmatch_t match[1];

	while (1) {

		const char *bol, *eol;

		reg_error = regexec(regexp, start, 1, match, 0);

		if (reg_error == REG_NOMATCH)

			return NULL;

		else if (reg_error) {

			char errbuf[1024];

			regerror(reg_error, regexp, errbuf, 1024);

			die("-L parameter: regexec() failed: %s", errbuf);

		}

		/* determine extent of line matched */

		bol = start+match[0].rm_so;

		eol = start+match[0].rm_eo;

		while (bol > start && *bol != '\n')

			bol--;

		if (*bol == '\n')

			bol++;

		while (*eol && *eol != '\n')

			eol++;

		if (*eol == '\n')

			eol++;

		/* is it a funcname line? */

		if (match_funcname(xecfg, (char*) bol, (char*) eol))

			return bol;

		start = eol;

	}

}

static const char *parse_range_funcname(

	const char *arg, nth_line_fn_t nth_line_cb,

	void *cb_data, long lines, long anchor, long *begin, long *end,

	const char *path, struct index_state *istate)

{

	char *pattern;

	const char *term;

	struct userdiff_driver *drv;

	xdemitconf_t *xecfg = NULL;

	const char *start;

	const char *p;

	int reg_error;

	regex_t regexp;

	if (*arg == '^') {

		anchor = 1;

		arg++;

	}

	assert(*arg == ':');

	term = arg+1;

	while (*term && *term != ':') {

		if (*term == '\\' && *(term+1))

			term++;

		term++;

	}

	if (term == arg+1)

		return NULL;

	if (!begin) /* skip_range_arg case */

		return term;

	pattern = xstrndup(arg+1, term-(arg+1));

	anchor--; /* input is in human terms */

	start = nth_line_cb(cb_data, anchor);

	drv = userdiff_find_by_path(istate, path);

	if (drv && drv->funcname.pattern) {

		const struct userdiff_funcname *pe = &drv->funcname;

		xecfg = xcalloc(1, sizeof(*xecfg));

		xdiff_set_find_func(xecfg, pe->pattern, pe->cflags);

	}

	reg_error = regcomp(&regexp, pattern, REG_NEWLINE);

	if (reg_error) {

		char errbuf[1024];

		regerror(reg_error, &regexp, errbuf, 1024);

		die("-L parameter '%s': %s", pattern, errbuf);

	}

	p = find_funcname_matching_regexp(xecfg, (char*) start, &regexp);

	if (!p)

		die("-L parameter '%s' starting at line %ld: no match",

		    pattern, anchor + 1);

	*begin = 0;

	while (p > nth_line_cb(cb_data, *begin))

		(*begin)++;

	if (*begin >= lines)

		die("-L parameter '%s' matches at EOF", pattern);

	*end = *begin+1;

	while (*end < lines) {

		const char *bol = nth_line_cb(cb_data, *end);

		const char *eol = nth_line_cb(cb_data, *end+1);

		if (match_funcname(xecfg, bol, eol))

			break;

		(*end)++;

	}

	regfree(&regexp);

	free(xecfg);

	free(pattern);

	/* compensate for 1-based numbering */

	(*begin)++;

	return term;

}

int parse_range_arg(const char *arg, nth_line_fn_t nth_line_cb,

		    void *cb_data, long lines, long anchor,

		    long *begin, long *end,

		    const char *path, struct index_state *istate)

{

	*begin = *end = 0;

	if (anchor < 1)

		anchor = 1;

	if (anchor > lines)

		anchor = lines + 1;

	if (*arg == ':' || (*arg == '^' && *(arg + 1) == ':')) {

		arg = parse_range_funcname(arg, nth_line_cb, cb_data,

					   lines, anchor, begin, end,

					   path, istate);

		if (!arg || *arg)

			return -1;

		return 0;

	}

	arg = parse_loc(arg, nth_line_cb, cb_data, lines, -anchor, begin);

	if (*arg == ',')

		arg = parse_loc(arg + 1, nth_line_cb, cb_data, lines, *begin + 1, end);

	if (*arg)

		return -1;

	if (*begin && *end && *end < *begin) {

		SWAP(*end, *begin);

	}

	return 0;

}

const char *skip_range_arg(const char *arg, struct index_state *istate)

{

	if (*arg == ':' || (*arg == '^' && *(arg + 1) == ':'))

		return parse_range_funcname(arg, NULL, NULL,

					    0, 0, NULL, NULL,

					    NULL, istate);

	arg = parse_loc(arg, NULL, NULL, 0, -1, NULL);

	if (*arg == ',')

		arg = parse_loc(arg+1, NULL, NULL, 0, 0, NULL);

	return arg;

}