/*
uchunk - user-visible chunking: how a user's input-consuming loop experiences a presence/absence of qualifying input
         slight generalization of "eof handling"; we called many of these cases the "eof tests" while first devising them

Coverage criteria include when an input-provided chunk exactly fills a user-provided buffer,
because the double-boundary case of "this happens just before eof" is (white-box) uchunk-relevant.
But cases of input-provided chunks exceeding the user's buffer live under
manipulatorsInput#pre* and ../collections/string-io-istream-manip#pre*.

Test design with subprocesses and auxiliary inputs is cargo-culted from
configs/parseconfig, configs/usage and io/many_read.
If you're here to cargo-cult, start there.

*/

#ifdef __cplusplus
  #include <iostream>
  #include <iomanip>
  #include <cstring>
  using namespace std;
  #define TRYREAD(str)      tryread(sizeof(str)-1, str);
  #define DETECT_EOF( ... ) __VA_ARGS__
  #define POLL_EOF          if ( cin.fail() ) break;
  #define ECHO(stg, str)    cout << #stg << " \"" << str << "\"" << str[sizeof(str)-1] << endl
#elif defined __cforall
  #include <fstream.hfa>
  extern "C" {
    char* strcpy(char*, const char*);
  }
  #define DETECT_EOF( ... ) \
    try { \
      __VA_ARGS__ \
    } catch ( end_of_file * ) {}
  #define TRYREAD(str)      try {                                             \
                                  tryread(sizeof(str)-1, str);                \
                            }                                                 \
                            catch ( cstring_length* ) {                       \
                                /* never expected; just harness robustness */ \
                                sout | "cstring_length and " | nonl;          \
                            }
  #define POLL_EOF
  #define ECHO(stg, str)    sout | #stg | " \"" | str | "\"" | str[sizeof(str)-1]
#else
  #error no
#endif



//
// BEGIN: functions only used in child process
//
// Parent process does not use test.py-provided stdin.
// Parent process uses test.py-provided IN_DIR, from which it explicitly opens files.
// Each child process sees content from one such file on its stdin.
// The functions in this section echo, from this distinct child stdin, to parent-bridged stdout.
//

void subcaseHarness( void (*tryread)(size_t, char*) ) {
    char s[10];
    DETECT_EOF (
      for (bool first = true ;; ) {
          strcpy(s, "---");  // every time: restore "---"x
          s[9] = 'x';
          if (first) {
            ECHO(BGN, s);    // first time: show it
            first = false;
          }

          TRYREAD(s)
          POLL_EOF
          ECHO(GOT, s);
      }
    )
    ECHO(END, s);
}

void tryread_default(size_t sizeof_s, char *s) {
  #ifdef __cplusplus
    cin >> setw( sizeof_s ) >> s;
  #else
    sin | wdi( sizeof_s, s );
  #endif
}

void tryread_getline(size_t sizeof_s, char *s) {
  #ifdef __cplusplus
    cin.getline(s, sizeof_s);
  #else
    sin | getline( wdi( sizeof_s, s ) );
  #endif
}

//
// END: functions only used in child process
//


extern "C" {
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <fcntl.h>
	#include <unistd.h>
}

#ifdef SUBCASE_ISOLATION

    #define x(s) s
    #define TRYREAD_FUNCTION x(tryread_ ## x(SUBCASE_ISOLATION))

    #define MK_TRYREAD_FUNCTION(x) tryread_ ## x

    #define _MAKEDATA(n) tryread_ ## n
    #define MAKEDATA(n) _MAKEDATA(n)

    int main() {
        subcaseHarness( MAKEDATA(SUBCASE_ISOLATION) );
    }

#else 
    #define xstr(s) str(s)
    #define str(s) #s

    #include "../meta/fork+exec.hfa"

    void forkJoinSubcase( void (*tryread)(size_t, char*), const char* subcase_name, const char* aux_in_fname ) {
        printf("--- %s ---\n", subcase_name);
        int aux_in_fd = open(aux_in_fname, 0);
        if( aux_in_fd < 0 ) {
            printf("Failed to open file: %s\n", aux_in_fname);
            exit(1);
        }
        if ( pid_t child_pid = strict_fork() ) {
            // in parent
            do_wait(child_pid);
        } else {
            // in child
            dup2(aux_in_fd, 0);  // make stdin pull from aux
            subcaseHarness( tryread );
            exit(0);
        }
    }

    #define SUBCASE_( TRYREAD_FUNCTION, IN_FILE_SLUG ) forkJoinSubcase( TRYREAD_FUNCTION, (IN_FILE_SLUG), (xstr(IN_DIR) "manipulatorsInput-uchunk." IN_FILE_SLUG ".txt") )
    #define SUBCASE( MANIP, IN_FILE_SUFFIX ) SUBCASE_( tryread_ ## MANIP, #MANIP "." #IN_FILE_SUFFIX )

    int main() {

        SUBCASE( default, 1 );
        SUBCASE( default, 2 );
        SUBCASE( default, 3 );
        SUBCASE( default, 4 );
        SUBCASE( default, 5 );
        SUBCASE( default, 6 );
        SUBCASE( default, 7 );
        SUBCASE( default, 8 );
        SUBCASE( default, 9 );
        SUBCASE( default, 10 );
        SUBCASE( default, 11 );
        SUBCASE( default, 12 );
        SUBCASE( default, 13 );
        SUBCASE( default, 14 );

        SUBCASE( getline, 1 );
        SUBCASE( getline, 2 );
        SUBCASE( getline, 3 );
        SUBCASE( getline, 4 );
        SUBCASE( getline, 5 );
        SUBCASE( getline, 6 );
        SUBCASE( getline, 7 );
        SUBCASE( getline, 8 );
        SUBCASE( getline, 9 );
        SUBCASE( getline, 10 );
        SUBCASE( getline, 11 );
        SUBCASE( getline, 12 );
        SUBCASE( getline, 13 );
        SUBCASE( getline, 14 );

        return 0;
    }

    // not used
    static int true_main(const char * path, const char * env[]) { return 0; }


#endif