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

/* Globals from cut.c are visible since this file is included into cut.c */
extern struct field_range_pair *frp;

/* Helper: build selection ranges and set frp.
   'pairs' is an array of {lo, hi} with 'count' entries.
   Returns the allocated array to be freed by the caller. */
static struct field_range_pair* set_frp_from_pairs(const uintmax_t (*pairs)[2], size_t count) {
  struct field_range_pair *arr = (struct field_range_pair*) malloc(sizeof(*arr) * (count + 1));
  if (!arr) return NULL;
  for (size_t i = 0; i < count; i++) {
    arr[i].lo = pairs[i][0];
    arr[i].hi = pairs[i][1];
  }
  /* Sentinel to ensure no stepping beyond valid ranges. */
  arr[count].lo = UINTMAX_MAX;
  arr[count].hi = UINTMAX_MAX;
  frp = arr;
  return arr;
}

/* Helper: run cut_fields on provided input string with given configuration,
   capturing stdout and returning the captured output in a malloc'ed string.
   The caller must free the returned string.
   out_delim_str==NULL => use default (input delimiter). */
static char* run_cut_fields_capture(
    const char *input,
    const uintmax_t (*pairs)[2], size_t npairs,
    unsigned char in_delim,
    const char *out_delim_str,
    bool only_delimited)
{
  /* Configure globals used by cut_fields. */
  suppress_non_delimited = only_delimited;

  /* Set input delimiter. */
  delim = in_delim;

  /* Configure default and actual output delimiter. */
  output_delimiter_default[0] = delim;
  if (out_delim_str == NULL) {
    output_delimiter_string = output_delimiter_default;
    output_delimiter_length = 1;
  } else {
    output_delimiter_string = (char*)out_delim_str;
    output_delimiter_length = strlen(out_delim_str);
  }

  /* Ensure line delimiter is standard newline for these tests. */
  line_delim = '\n';

  /* Set selection ranges. */
  struct field_range_pair *local_frp = set_frp_from_pairs(pairs, npairs);
  if (!local_frp) {
    /* Allocation failure – return a copy of empty string to avoid NULL. */
    char *empty = (char*)malloc(1);
    if (empty) empty[0] = '\0';
    return empty;
  }

  /* Prepare input stream. */
  FILE *in = tmpfile();
  if (!in) {
    free(local_frp);
    char *empty = (char*)malloc(1);
    if (empty) empty[0] = '\0';
    return empty;
  }
  if (input && *input) {
    fwrite(input, 1, strlen(input), in);
  }
  fflush(in);
  fseek(in, 0, SEEK_SET);

  /* Capture stdout to a temporary file. */
  fflush(stdout);
  int saved_stdout_fd = dup(fileno(stdout));
  FILE *cap = tmpfile();
  if (cap == NULL) {
    fclose(in);
    free(local_frp);
    char *empty = (char*)malloc(1);
    if (empty) empty[0] = '\0';
    return empty;
  }
  dup2(fileno(cap), fileno(stdout));
  clearerr(stdout);

  /* Call target function. */
  cut_fields(in);

  /* Stop capturing and restore stdout. */
  fflush(stdout);
  dup2(saved_stdout_fd, fileno(stdout));
  close(saved_stdout_fd);

  /* Read captured output into a buffer. */
  fflush(cap);
  fseek(cap, 0, SEEK_END);
  long sz = ftell(cap);
  if (sz < 0) sz = 0;
  fseek(cap, 0, SEEK_SET);
  char *out = (char*)malloc((size_t)sz + 1);
  if (!out) {
    out = (char*)malloc(1);
    if (out) out[0] = '\0';
  } else {
    size_t nread = fread(out, 1, (size_t)sz, cap);
    out[nread] = '\0';
  }

  /* Cleanup. */
  fclose(cap);
  fclose(in);
  free(local_frp);

  return out;
}

void setUp(void) {
  /* Ensure a clean starting state for globals influenced by previous calls. */
  suppress_non_delimited = false;
  /* Default delimiters */
  delim = '\t';
  line_delim = '\n';
  output_delimiter_default[0] = delim;
  output_delimiter_string = output_delimiter_default;
  output_delimiter_length = 1;
}

void tearDown(void) {
  /* Release buffer possibly allocated by cut_fields. */
  if (field_1_buffer) {
    free(field_1_buffer);
    field_1_buffer = NULL;
    field_1_bufsize = 0;
  }
}

/* Test: Basic selection with default delimiter (TAB): select fields 2-3. */
void test_cut_fields_basic_selection_default_delim(void) {
  const char *input = "a\tb\tc\n1\t2\t3\n";
  const uintmax_t pairs[][2] = { {2,3} };
  char *out = run_cut_fields_capture(input, pairs, 1, '\t', NULL, false);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_STRING("b\tc\n2\t3\n", out);
  free(out);
}

/* Test: Non-delimited line without -s should be printed unchanged. */
void test_cut_fields_nondelimited_without_s(void) {
  const char *input = "abc\n";
  const uintmax_t pairs[][2] = { {2,2} }; /* select field 2 */
  char *out = run_cut_fields_capture(input, pairs, 1, ',', NULL, false);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_STRING("abc\n", out);
  free(out);
}

/* Test: Non-delimited line with -s should be suppressed entirely. */
void test_cut_fields_nondelimited_with_s(void) {
  const char *input = "abc\n";
  const uintmax_t pairs[][2] = { {1,1} }; /* select field 1 */
  char *out = run_cut_fields_capture(input, pairs, 1, ',', NULL, true);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_STRING("", out);
  free(out);
}

/* Test: Custom output delimiter between selected fields (select 1 and 3). */
void test_cut_fields_custom_output_delimiter(void) {
  const char *input = "a,b,c\nx,y,z\n";
  const uintmax_t pairs[][2] = { {1,1}, {3,3} };
  char *out = run_cut_fields_capture(input, pairs, 2, ',', ":", false);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_STRING("a:c\nx:z\n", out);
  free(out);
}

/* Test: Line has delimiters but not enough fields; output should be empty line(s). */
void test_cut_fields_missing_field_produces_empty_line(void) {
  const char *input = "a,b\nx,y\n";
  const uintmax_t pairs[][2] = { {3,3} }; /* third field does not exist */
  char *out = run_cut_fields_capture(input, pairs, 1, ',', NULL, false);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_STRING("\n\n", out);
  free(out);
}

/* Test: Input without trailing newline – ensure output is newline-terminated. */
void test_cut_fields_no_trailing_newline(void) {
  const char *input = "a,b,c";
  const uintmax_t pairs[][2] = { {2,2} }; /* select field 2 */
  char *out = run_cut_fields_capture(input, pairs, 1, ',', NULL, false);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_STRING("b\n", out);
  free(out);
}

/* Test: Empty selected field (adjacent delimiters) should yield empty output for that line. */
void test_cut_fields_empty_selected_field(void) {
  const char *input = "a,,c\n";
  const uintmax_t pairs[][2] = { {2,2} }; /* select empty field 2 */
  char *out = run_cut_fields_capture(input, pairs, 1, ',', NULL, false);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_STRING("\n", out);
  free(out);
}

int main(void) {
  UNITY_BEGIN();
  RUN_TEST(test_cut_fields_basic_selection_default_delim);
  RUN_TEST(test_cut_fields_nondelimited_without_s);
  RUN_TEST(test_cut_fields_nondelimited_with_s);
  RUN_TEST(test_cut_fields_custom_output_delimiter);
  RUN_TEST(test_cut_fields_missing_field_produces_empty_line);
  RUN_TEST(test_cut_fields_no_trailing_newline);
  RUN_TEST(test_cut_fields_empty_selected_field);
  return UNITY_END();
}