#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

#include <fcntl.h>
#include <io.h>

#define NO_MAIN 1
#include "gzip_nop.c"

#define READ_PIPE 0
#define WRITE_PIPE 1

// Tests that passing a randomly-generated byte stream through the "gzip"
// function, then passing the gzipped output back through the "gunzip" program,
// results in the same randomly-generated byte stream.
//
// This test uses Windows-specific API calls, and is not portable to other
// systems.
int main(void) {
    // Generate original random byte stream
    uint8_t input_buffer[UINT16_MAX + 256] = {0};
    for (size_t i = 0; i < sizeof(input_buffer); i++) {
        input_buffer[i] = rand();
    }

    int input_pipe[2];
    int gzipped_pipe[2];
    int output_pipe[2];

    assert(_pipe(input_pipe, sizeof(input_buffer) + 256, _O_BINARY) != -1);
    assert(_pipe(gzipped_pipe, sizeof(input_buffer) + 256, _O_BINARY) != -1);
    assert(_pipe(output_pipe, sizeof(input_buffer) + 256, _O_BINARY) != -1);

    assert(write(input_pipe[WRITE_PIPE], input_buffer, sizeof(input_buffer)) ==
           sizeof(input_buffer));
    assert(close(input_pipe[WRITE_PIPE]) != -1);

    FILE *input_stream = fdopen(input_pipe[READ_PIPE], "rb");
    assert(input_stream != NULL);

    FILE *gzipped_stream = fdopen(gzipped_pipe[WRITE_PIPE], "wb");
    assert(gzipped_stream != NULL);

    // Apply GZIP to original randomly-generated byte stream
    gzip(input_stream, gzipped_stream);
    assert(fclose(gzipped_stream) != EOF);

    // Run external gunzip program to decompress the gzipped byte stream
    char command_buffer[256];
    int len = snprintf(command_buffer, sizeof(command_buffer),
                       "gzip --decompress --stdout <&%d >&%d",
                       gzipped_pipe[READ_PIPE], output_pipe[WRITE_PIPE]);
    assert(len > 0 && (size_t)len < sizeof(command_buffer));
    assert(system(command_buffer) == EXIT_SUCCESS);

    uint8_t output_buffer[sizeof(input_buffer) + 256] = {0};
    len = read(output_pipe[READ_PIPE], output_buffer, sizeof(output_buffer));

    // Assert that the decompressed byte stream is identical to the original
    // randomly-generated byte stream
    int got = len, want = sizeof(input_buffer);
    if (got != want) {
        fprintf(stderr, "Output length = %d, want %d", got, want);
        exit(EXIT_FAILURE);
    }

    for (int i = 0; i < len; i++) {
        uint8_t got = input_buffer[i], want = output_buffer[i];
        if (got != want) {
            fprintf(stderr, "Output[%d] = %x, want %x", i, got, want);
            exit(EXIT_FAILURE);
        }
    }

    return EXIT_SUCCESS;
}