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

/* The test file is included within the same translation unit as csplit.c,
   so we can reference its internal static symbols directly. */

/* Helpers to manage input/output for tests */

static void test_prepare_stdin(const char *data)
{
    int fds[2];
    if (pipe(fds) != 0) {
        /* Can't use Unity asserts if stdout is redirected, but it's not here. */
        TEST_FAIL_MESSAGE("pipe() failed");
    }

    /* Write all data and close write end to signal EOF */
    ssize_t len = (ssize_t)strlen(data);
    ssize_t written = 0;
    while (written < len) {
        ssize_t w = write(fds[1], data + written, len - written);
        if (w < 0) {
            close(fds[0]);
            close(fds[1]);
            TEST_FAIL_MESSAGE("write() to pipe failed");
        }
        written += w;
    }
    close(fds[1]);

    /* Replace stdin with read end of the pipe */
    if (dup2(fds[0], STDIN_FILENO) < 0) {
        close(fds[0]);
        TEST_FAIL_MESSAGE("dup2() failed");
    }
    close(fds[0]);
}

/* Remove files created by csplit for current prefix/suffix configuration. */
static void test_remove_created_files(void)
{
    /* delete_all_files is internal and deletes only on error if remove_files is set.
       We manually unlink created files here. */
    if (files_created > 0) {
        for (int i = files_created - 1; i >= 0; --i) {
            const char *name = make_filename(i);
            unlink(name);
        }
    }
    files_created = 0;
}

/* Read whole file into a malloc'ed buffer (null-terminated). Caller frees. */
static char *test_slurp_file(const char *path)
{
    FILE *fp = fopen(path, "rb");
    if (!fp) return NULL;
    if (fseek(fp, 0, SEEK_END) != 0) {
        fclose(fp);
        return NULL;
    }
    long sz = ftell(fp);
    if (sz < 0) {
        fclose(fp);
        return NULL;
    }
    if (fseek(fp, 0, SEEK_SET) != 0) {
        fclose(fp);
        return NULL;
    }
    char *buf = (char *)malloc((size_t)sz + 1);
    if (!buf) {
        fclose(fp);
        return NULL;
    }
    size_t n = fread(buf, 1, (size_t)sz, fp);
    fclose(fp);
    buf[n] = '\0';
    return buf;
}

/* Drain any remaining lines to fully free buffers and reset internal prev_buf. */
static void test_drain_all_input(void)
{
    struct cstring *ln;
    while ((ln = remove_line()) != NULL) {
        (void)ln;
    }
}

/* Minimal argv to satisfy any error path references (not used in success tests). */
static char *test_argv_storage[4] = { (char *)"csplit", (char *)"/dummy/", (char *)"%dummy%", NULL };

/* Common setup before each test. */
void setUp(void) {
    /* Reset output behavior to avoid stdout noise from counts */
    suppress_count = true;
    elide_empty_files = false;
    remove_files = false;
    suppress_matched = false;

    /* Filename generation setup */
    if (!filename_space) {
        filename_space = (char *)malloc(512);
        TEST_ASSERT_NOT_NULL_MESSAGE(filename_space, "malloc filename_space failed");
    }
    prefix = "tstpr_";
    suffix = NULL;
    digits = 2;

    /* Signals set to empty to avoid blocking issues */
    sigemptyset(&caught_signals);

    /* Input/buffer state reset */
    head = NULL;
    if (hold_area) { free(hold_area); hold_area = NULL; }
    hold_count = 0;
    have_read_eof = false;
    last_line_number = 0;
    current_line = 0;

    /* Output state reset */
    bytes_written = 0;
    output_stream = NULL;
    output_filename = NULL;
    files_created = 0;

    /* Argv context */
    global_argv = test_argv_storage;
}

/* Cleanup after each test. */
void tearDown(void) {
    /* Close any open output file cleanly */
    close_output_file();

    /* Drain any buffered input to reset internal state like prev_buf */
    test_drain_all_input();

    /* Remove any created files */
    test_remove_created_files();

    /* Reset key input state for safety */
    head = NULL;
    if (hold_area) { free(hold_area); hold_area = NULL; }
    hold_count = 0;
    have_read_eof = false;
    last_line_number = 0;
    current_line = 0;
}

/* Helpers to build control structures via existing parser */
static struct control *test_make_regexp_control(int argnum, const char *pattern_with_delims)
{
    /* extract_regexp sets ignore based on delimiter: '/' -> false, '%' -> true */
    struct control *p = extract_regexp(argnum, (pattern_with_delims[0] == '%'), pattern_with_delims);
    return p;
}

/* Return last created filename (or NULL if none). */
static const char *test_last_filename(void)
{
    if (files_created <= 0) return NULL;
    return make_filename(files_created - 1);
}

/* Tests */

static void test_process_regexp_match_no_offset_writes_preceding_lines(void)
{
    /* Input: lines before, match, after */
    const char *input = "one\nfoo\nbar\n";
    test_prepare_stdin(input);

    /* Build control for /foo/ (no offset, not ignore) */
    test_argv_storage[1] = (char *)"/foo/";
    struct control *p = test_make_regexp_control(1, "/foo/");

    /* Run */
    process_regexp(p, 0);

    /* Verify one file created containing only lines before the match */
    TEST_ASSERT_EQUAL_INT(1, files_created);
    const char *fname = test_last_filename();
    TEST_ASSERT_NOT_NULL(fname);
    char *content = test_slurp_file(fname);
    TEST_ASSERT_NOT_NULL_MESSAGE(content, "Failed to read output file");
    TEST_ASSERT_EQUAL_STRING("one\n", content);
    free(content);
}

static void test_process_regexp_positive_offset_includes_matching_line(void)
{
    const char *input = "a\nfoo\nc\n";
    test_prepare_stdin(input);

    /* /foo/+1 should include the matching line as well */
    test_argv_storage[1] = (char *)"/foo/+1";
    struct control *p = test_make_regexp_control(1, "/foo/+1");

    process_regexp(p, 0);

    TEST_ASSERT_EQUAL_INT(1, files_created);
    const char *fname = test_last_filename();
    TEST_ASSERT_NOT_NULL(fname);
    char *content = test_slurp_file(fname);
    TEST_ASSERT_NOT_NULL(content);
    TEST_ASSERT_EQUAL_STRING("a\nfoo\n", content);
    free(content);
}

static void test_process_regexp_ignore_true_creates_no_files(void)
{
    const char *input = "a\nfoo\nb\n";
    test_prepare_stdin(input);

    /* %foo% -> ignore the section (no output file should be created) */
    test_argv_storage[2] = (char *)"%foo%";
    struct control *p = test_make_regexp_control(2, "%foo%");

    process_regexp(p, 0);

    TEST_ASSERT_EQUAL_INT(0, files_created);
    /* And no file to check */
}

static void test_process_regexp_negative_offset_writes_up_to_before_previous_line(void)
{
    const char *input = "a\nb\nc\nd\n";
    test_prepare_stdin(input);

    /* /c/-1: cut 1 line before the match "c", so only "a\n" is written */
    test_argv_storage[1] = (char *)"/c/-1";
    struct control *p = test_make_regexp_control(1, "/c/-1");

    process_regexp(p, 0);

    TEST_ASSERT_EQUAL_INT(1, files_created);
    const char *fname = test_last_filename();
    TEST_ASSERT_NOT_NULL(fname);
    char *content = test_slurp_file(fname);
    TEST_ASSERT_NOT_NULL(content);
    TEST_ASSERT_EQUAL_STRING("a\n", content);
    free(content);
}

static void test_process_regexp_suppress_matched_skips_matched_line(void)
{
    const char *input = "before\nmatch\nafter\n";
    test_prepare_stdin(input);

    suppress_matched = true;

    test_argv_storage[1] = (char *)"/match/";
    struct control *p = test_make_regexp_control(1, "/match/");

    process_regexp(p, 0);

    /* File should contain only "before\n" */
    TEST_ASSERT_EQUAL_INT(1, files_created);
    const char *fname = test_last_filename();
    TEST_ASSERT_NOT_NULL(fname);
    char *content = test_slurp_file(fname);
    TEST_ASSERT_NOT_NULL(content);
    TEST_ASSERT_EQUAL_STRING("before\n", content);
    free(content);

    /* The matched line should be suppressed; next line should be "after\n" */
    struct cstring *next = remove_line();
    TEST_ASSERT_NOT_NULL(next);
    TEST_ASSERT_EQUAL_INT_MESSAGE((int)strlen("after\n"), (int)next->len, "Unexpected next line length");
    TEST_ASSERT_EQUAL_INT(0, strncmp(next->str, "after\n", next->len));
}

/* Unity main */
int main(void)
{
    UNITY_BEGIN();
    RUN_TEST(test_process_regexp_match_no_offset_writes_preceding_lines);
    RUN_TEST(test_process_regexp_positive_offset_includes_matching_line);
    RUN_TEST(test_process_regexp_ignore_true_creates_no_files);
    RUN_TEST(test_process_regexp_negative_offset_writes_up_to_before_previous_line);
    RUN_TEST(test_process_regexp_suppress_matched_skips_matched_line);
    return UNITY_END();
}