#include "../../unity/unity.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

/* We rely on the program's static globals and the target function being
   visible here due to textual inclusion into the same translation unit. */

/* Helper to construct a line with given fields. Allocates memory for the
   fields and their contents. */
static void build_line(struct line *ln, const char *const *vals, const idx_t *lens, idx_t n)
{
    memset(ln, 0, sizeof(*ln));
    ln->nfields = n;
    ln->nfields_allocated = n;
    if (n == 0) {
        ln->fields = NULL;
        return;
    }
    ln->fields = (struct field *)malloc(sizeof(struct field) * n);
    for (idx_t i = 0; i < n; ++i) {
        idx_t L = lens ? lens[i] : (idx_t)strlen(vals[i]);
        char *buf = (char *)malloc((size_t)L);
        if (L > 0) {
            memcpy(buf, vals[i], (size_t)L);
        }
        ln->fields[i].beg = buf;
        ln->fields[i].len = L;
    }
}

/* Helper to free memory allocated by build_line. */
static void free_line(struct line *ln)
{
    if (!ln) return;
    for (idx_t i = 0; i < ln->nfields; ++i) {
        free(ln->fields[i].beg);
        ln->fields[i].beg = NULL;
        ln->fields[i].len = 0;
    }
    free(ln->fields);
    ln->fields = NULL;
    ln->nfields = 0;
    ln->nfields_allocated = 0;
}

/* Capture stdout output produced by calling prfields(line, join_field, autocount).
   Returns a malloc'd NUL-terminated string on success, or NULL on failure. */
static char *capture_prfields_output(struct line const *line, idx_t join_field, idx_t autocount)
{
    char *result = NULL;
    FILE *tmp = tmpfile();
    if (!tmp) {
        return NULL;
    }

    int out_fd = fileno(stdout);
    int saved_fd = dup(out_fd);
    if (saved_fd < 0) {
        fclose(tmp);
        return NULL;
    }

    int tmp_fd = fileno(tmp);

    /* Redirect stdout to tmp. */
    fflush(stdout);
    if (dup2(tmp_fd, out_fd) < 0) {
        close(saved_fd);
        fclose(tmp);
        return NULL;
    }

    /* Call the target function while stdout is redirected. */
    prfields(line, join_field, autocount);

    /* Flush and read back the captured output. */
    fflush(stdout);
    long size = 0;
    if (fseek(tmp, 0, SEEK_END) == 0) {
        long endpos = ftell(tmp);
        if (endpos >= 0) {
            size = endpos;
            (void)fseek(tmp, 0, SEEK_SET);
        }
    }

    if (size < 0) size = 0;
    result = (char *)malloc((size_t)size + 1);
    if (!result) {
        /* Restore stdout before returning. */
        dup2(saved_fd, out_fd);
        close(saved_fd);
        fclose(tmp);
        return NULL;
    }

    if (size > 0) {
        size_t rd = fread(result, 1, (size_t)size, tmp);
        result[rd] = '\0';
        if (rd != (size_t)size) {
            /* Restore stdout and report failure. */
            dup2(saved_fd, out_fd);
            close(saved_fd);
            fclose(tmp);
            free(result);
            return NULL;
        }
    } else {
        result[0] = '\0';
    }

    /* Restore stdout. */
    dup2(saved_fd, out_fd);
    close(saved_fd);
    fclose(tmp);
    return result;
}

void setUp(void) {
    /* Default settings before each test. */
    autoformat = false;
    output_separator = " ";
    output_seplen = 1;
    empty_filler = NULL;
}

void tearDown(void) {
    /* Nothing persistent to clean up across tests. */
}

/* Test: basic behavior, skip the join field in the middle. */
static void test_prfields_basic_skip_join_middle(void)
{
    const char *vals[] = { "A", "B", "C" };
    struct line ln;
    build_line(&ln, vals, NULL, 3);

    output_separator = ",";
    output_seplen = (idx_t)strlen(output_separator);
    autoformat = false;
    empty_filler = NULL;

    char *out = capture_prfields_output(&ln, (idx_t)1, (idx_t)0);
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_EQUAL_STRING(",A,C", out);

    free(out);
    free_line(&ln);
}

/* Test: join_field out of range (greater than number of fields) -> no skip, all printed. */
static void test_prfields_join_field_out_of_range_high(void)
{
    const char *vals[] = { "A", "B", "C" };
    struct line ln;
    build_line(&ln, vals, NULL, 3);

    output_separator = ",";
    output_seplen = 1;
    autoformat = false;

    char *out = capture_prfields_output(&ln, (idx_t)5, (idx_t)0);
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_EQUAL_STRING(",A,B,C", out);

    free(out);
    free_line(&ln);
}

/* Test: no fields present -> no output. */
static void test_prfields_no_fields_no_output(void)
{
    struct line ln;
    build_line(&ln, NULL, NULL, 0);

    output_separator = ",";
    output_seplen = 1;
    autoformat = false;

    char *out = capture_prfields_output(&ln, (idx_t)0, (idx_t)0);
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_EQUAL_STRING("", out);

    free(out);
    free_line(&ln);
}

/* Test: empty field replaced by empty_filler when printed (non-join field). */
static void test_prfields_empty_field_with_empty_filler(void)
{
    const char *vals[] = { "A", "", "C" };
    idx_t lens[] = { 1, 0, 1 }; /* explicit lengths to create an empty field */
    struct line ln;
    build_line(&ln, vals, lens, 3);

    output_separator = ",";
    output_seplen = 1;
    autoformat = false;
    empty_filler = "<E>";

    /* Use join_field = 0 so fields 1 and 2 are printed. */
    char *out = capture_prfields_output(&ln, (idx_t)0, (idx_t)0);
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_EQUAL_STRING(",<E>,C", out);

    free(out);
    free_line(&ln);
}

/* Test: autoformat extends beyond existing fields and uses empty_filler for missing ones. */
static void test_prfields_autoformat_extends_and_fills(void)
{
    const char *vals[] = { "A", "B" };
    struct line ln;
    build_line(&ln, vals, NULL, 2);

    output_separator = ",";
    output_seplen = 1;
    autoformat = true;
    empty_filler = "<E>";

    /* join_field = 0 -> print indices 1..3; ln has only index 1, so 2 and 3 use filler */
    char *out = capture_prfields_output(&ln, (idx_t)0, (idx_t)4);
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_EQUAL_STRING(",B,<E>,<E>", out);

    free(out);
    free_line(&ln);
}

/* Test: autoformat limits output to autocount even if there are more fields; join field skipped. */
static void test_prfields_autoformat_limits(void)
{
    const char *vals[] = { "A", "B", "C", "D" };
    struct line ln;
    build_line(&ln, vals, NULL, 4);

    output_separator = ",";
    output_seplen = 1;
    autoformat = true;
    empty_filler = NULL;

    /* nfields considered = 3 (autocount). join_field = 2 => print 0 and 1 only. */
    char *out = capture_prfields_output(&ln, (idx_t)2, (idx_t)3);
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_EQUAL_STRING(",A,B", out);

    free(out);
    free_line(&ln);
}

/* Test: custom multi-character separator honors output_seplen. */
static void test_prfields_custom_separator_multichar(void)
{
    const char *vals[] = { "X", "Y" };
    struct line ln;
    build_line(&ln, vals, NULL, 2);

    output_separator = "::";
    output_seplen = (idx_t)strlen(output_separator);
    autoformat = false;

    /* join_field = 1 => print only field 0 */
    char *out = capture_prfields_output(&ln, (idx_t)1, (idx_t)0);
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_EQUAL_STRING("::X", out);

    free(out);
    free_line(&ln);
}

/* Test: autoformat with missing fields and no empty_filler prints only separators for those fields. */
static void test_prfields_autoformat_no_empty_filler_only_separators(void)
{
    const char *vals[] = { "A" };
    struct line ln;
    build_line(&ln, vals, NULL, 1);

    output_separator = ",";
    output_seplen = 1;
    autoformat = true;
    empty_filler = NULL;

    /* join_field = 0; autocount=3 -> attempt to print fields 1 and 2 (both missing):
       separators appear, but no filler text. */
    char *out = capture_prfields_output(&ln, (idx_t)0, (idx_t)3);
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_EQUAL_STRING(",,", out);

    free(out);
    free_line(&ln);
}

int main(void)
{
    UNITY_BEGIN();
    RUN_TEST(test_prfields_basic_skip_join_middle);
    RUN_TEST(test_prfields_join_field_out_of_range_high);
    RUN_TEST(test_prfields_no_fields_no_output);
    RUN_TEST(test_prfields_empty_field_with_empty_filler);
    RUN_TEST(test_prfields_autoformat_extends_and_fills);
    RUN_TEST(test_prfields_autoformat_limits);
    RUN_TEST(test_prfields_custom_separator_multichar);
    RUN_TEST(test_prfields_autoformat_no_empty_filler_only_separators);
    return UNITY_END();
}