/*
 * revdep - reverse dependency checker for rawnix
 * lang.c - detect packages with stale Python versioned paths
 *
 * Copyright (c) 2025 zorz@gmx.com
 * Licensed under the BSD 2-Clause License. See revdep.h.
 *
 * On a Python major version bump (e.g. 3.13 → 3.14), packages that
 * installed files into /usr/lib/python3.13/ become silently broken:
 * their .py and .so files are unreachable at the new path.  ELF
 * inspection cannot detect this because Python extension modules are
 * dlopen()'d at runtime using constructed path strings, not DT_NEEDED.
 *
 * Strategy:
 *   1. Find the installed "python3" package in the db and parse its
 *      major.minor version string (e.g. "3.14" from "3.14.2").
 *   2. For every file owned by every other package, check whether the
 *      path contains /usr/lib/pythonX.Y/ where X.Y ≠ installed version.
 *   3. Report those packages as broken.
 */

#define _POSIX_C_SOURCE 200809L

#include "revdep.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* prefix we scan for */
#define PY_PREFIX      "/usr/lib/python"
#define PY_PREFIX_LEN  (sizeof(PY_PREFIX) - 1)

/*
 * py_installed_version()
 *
 * Walk pkgs looking for a package named "python3".
 * Return a newly allocated "X.Y" string, or NULL if not found.
 */
char *
py_installed_version(const pkgvec_t *pkgs)
{
	size_t i;
	const char *ver;
	char *up, *dot2;
	char buf[32];
	size_t len;

	if (!pkgs)
		return NULL;

	for (i = 0; i < pkgs->count; i++) {
		if (strcmp(pkgs->items[i]->name, "python3") != 0)
			continue;

		/* the db has "3.14.2-1": version-release */
		up = pkg_upstream_version(pkgs->items[i]->version);
		if (!up)
			return NULL;
		ver = up;

		/* copy up to the second dot: "3.14.2" → "3.14" */
		dot2 = strchr(ver, '.');
		if (!dot2)
			return up;             /* no dot: use as-is */

		dot2 = strchr(dot2 + 1, '.');
		if (dot2)
			len = (size_t)(dot2 - ver);
		else
			len = strlen(ver);

		if (len >= sizeof(buf))
			len = sizeof(buf) - 1;

		memcpy(buf, ver, len);
		buf[len] = '\0';
		free(up);
		return xstrdup(buf);
	}

	return NULL;   /* python3 not installed */
}

/*
 * py_check_file()
 *
 * Return true if `path` is under /usr/lib/pythonX.Y/ and X.Y
 * does NOT match `installed`.
 *
 * Examples:
 *   path=/usr/lib/python3.13/site-packages/xcbgen/__init__.py
 *   installed="3.14"  →  stale, return true
 *
 *   path=/usr/lib/python3.14/site-packages/foo.py
 *   installed="3.14"  →  current, return false
 */
static bool
py_check_file(const char *path, const char *installed)
{
	const char *p, *slash;
	size_t verlen;
	char pathver[32];

	if (!path || !installed)
		return false;

	/* fast prefix check */
	if (strncmp(path, PY_PREFIX, PY_PREFIX_LEN) != 0)
		return false;

	/* p now points to the version string in the path */
	p = path + PY_PREFIX_LEN;

	/* find the next slash — that delimits the version component */
	slash = strchr(p, '/');
	if (!slash)
		return false;

	verlen = (size_t)(slash - p);
	if (verlen == 0 || verlen >= sizeof(pathver))
		return false;

	memcpy(pathver, p, verlen);
	pathver[verlen] = '\0';

	/* stale if version differs from installed */
	return strcmp(pathver, installed) != 0;
}

/*
 * py_check_package()
 *
 * Returns true if the package has at least one file under a stale
 * /usr/lib/pythonX.Y/ directory.  Prints details at appropriate
 * verbosity levels (matching the ELF checker style).
 */
bool
py_check_package(const pkg_t *pkg, const char *installed)
{
	size_t i;
	bool broken = false;

	if (!pkg || !installed || pkg->ignore)
		return false;

	for (i = 0; i < pkg->files.count; i++) {
		const char *path = pkg->files.items[i];

		if (!py_check_file(path, installed))
			continue;

		if (!broken) {
			msg(V_FILES, "  %s: stale python path\n", pkg->name);
			broken = true;
		}
		msg(V_DETAIL, "  %s: %s (expects python%s)\n",
		    pkg->name, path, installed);
	}

	return broken;
}

/* -------------------------------------------------------------------- */
/*  Perl versioned path checker                                         */
/*                                                                      */
/*  Same problem as Python: on a Perl major version bump, packages      */
/*  with files under /usr/lib/perl5/site_perl/5.X.Y/ become stale.     */
/* -------------------------------------------------------------------- */

#define PERL_PREFIX     "/usr/lib/perl5/site_perl/"
#define PERL_PREFIX_LEN (sizeof(PERL_PREFIX) - 1)

/*
 * perl_installed_version()
 *
 * Find the "perl" package in the db and return its version string
 * (e.g. "5.40.0").  The caller should compare the full X.Y.Z since
 * Perl ABI paths include all three components.
 */
char *
perl_installed_version(const pkgvec_t *pkgs)
{
	size_t i;

	if (!pkgs)
		return NULL;

	for (i = 0; i < pkgs->count; i++) {
		if (strcmp(pkgs->items[i]->name, "perl") != 0)
			continue;
		/* the db has "5.40.1-1"; site_perl uses "5.40.1" */
		return pkg_upstream_version(pkgs->items[i]->version);
	}

	return NULL;
}

/*
 * perl_check_file()
 *
 * Return true if path is under /usr/lib/perl5/site_perl/X.Y.Z/ and
 * X.Y.Z does NOT match installed.
 */
static bool
perl_check_file(const char *path, const char *installed)
{
	const char *p, *slash;
	size_t verlen;
	char pathver[32];

	if (!path || !installed)
		return false;

	if (strncmp(path, PERL_PREFIX, PERL_PREFIX_LEN) != 0)
		return false;

	p = path + PERL_PREFIX_LEN;

	slash = strchr(p, '/');
	if (!slash)
		return false;

	verlen = (size_t)(slash - p);
	if (verlen == 0 || verlen >= sizeof(pathver))
		return false;

	memcpy(pathver, p, verlen);
	pathver[verlen] = '\0';

	return strcmp(pathver, installed) != 0;
}

/*
 * perl_check_package()
 *
 * Returns true if the package has at least one file under a stale
 * /usr/lib/perl5/site_perl/X.Y.Z/ directory.
 */
bool
perl_check_package(const pkg_t *pkg, const char *installed)
{
	size_t i;
	bool broken = false;

	if (!pkg || !installed || pkg->ignore)
		return false;

	for (i = 0; i < pkg->files.count; i++) {
		const char *path = pkg->files.items[i];

		if (!perl_check_file(path, installed))
			continue;

		if (!broken) {
			msg(V_FILES, "  %s: stale perl path\n", pkg->name);
			broken = true;
		}
		msg(V_DETAIL, "  %s: %s (expects perl%s)\n",
		    pkg->name, path, installed);
	}

	return broken;
}