#ifndef CST_OS_COMPAT_H
#define CST_OS_COMPAT_H

#include <stddef.h>
#include <time.h>

#ifdef __cplusplus
extern "C" {
#endif

#ifndef OS_PATH_MAX
#define OS_PATH_MAX 4096
#endif

/* --- path --- */
int os_path_is_abs(const char *p);
/* Join with native separator; out always uses '/' on Unix and '\\' on Win for
 * the joiner, but os_path_norm_slashes converts to '/' for comparisons. */
int os_path_join(char *out, size_t out_sz, const char *a, const char *b);
void os_path_norm_slashes(char *p);
int os_realpath(const char *path, char *out, size_t out_sz);
/* True if path is under root (after realpath/norm). Trailing slash rules apply. */
int os_path_under(const char *root, const char *path);

/* --- dirs / config --- */
int os_mkdir(const char *path, int mode);
int os_mkdir_p(const char *path, int mode);
int os_config_dir(char *out, size_t out_sz);
int os_temp_dir(char *out, size_t out_sz);
/* Create unique temp file; writes path into out; returns fd or -1. Caller closes. */
int os_mkstemp(char *out, size_t out_sz, const char *prefix);

/* Directory containing the running executable (for bundled busybox).
 * Call os_set_prog_path(argv[0]) early on Unix/Termux as fallback. */
void os_set_prog_path(const char *argv0);
int os_exe_dir(char *out, size_t out_sz);

/* Resolve shell interpreter path into out.
 * Order: CST_SHELL → <exe_dir>/busybox[.exe] → /bin/sh (Unix). */
int os_resolve_shell(char *out, size_t out_sz);

/* --- process --- */
typedef struct {
  char *out;
  size_t out_len;
  int exit_code;
} os_run_result_t;

void os_run_result_free(os_run_result_t *r);

/* Run argv[0..] (NULL-terminated) with cwd; capture stdout+stderr.
 * max_out caps captured bytes (0 = default 512KiB). */
int os_run_capture(const char *cwd, const char *const argv[], size_t max_out,
                   os_run_result_t *r);

/* Convenience: shell -c cmd via os_resolve_shell. */
int os_run_shell_c(const char *cwd, const char *cmd, size_t max_out,
                   os_run_result_t *r);

/* Child processes get stdin=/dev/null, their own process group, and are
 * killed after the timeout (CST_SHELL_TIMEOUT seconds, default 120) or when
 * *flag becomes non-zero. Exit code 124 = timeout, 130 = cancelled. */
void os_set_cancel_flag(volatile int *flag);
void os_set_run_timeout(int seconds);

/* Monotonic milliseconds (arbitrary epoch). */
double os_now_ms(void);

/* --- misc --- */
void os_localtime(const time_t *t, struct tm *out);
int os_getpid(void);
int os_chmod_private(const char *path); /* best-effort 0600; no-op/ok on Win */

#ifdef __cplusplus
}
#endif

#endif /* CST_OS_COMPAT_H */