#define _GNU_SOURCE
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include <unity/unity.h>

#include "configcompare.h"

static char g_dir[256];

static void fresh_dir(void)
{
    strcpy(g_dir, "/tmp/xce_configcompare_XXXXXX");
    TEST_ASSERT_NOT_NULL(mkdtemp(g_dir));
}

static void cleanup_dir(void)
{
    char cmd[512];
    snprintf(cmd, sizeof(cmd), "rm -rf %s", g_dir);
    system(cmd);
}

/* Creates <root>/<name>/conf/ (a member's `workdir/name` directory, mirroring
 * conf_dir = "%s/%s", myconf->workdir, myconf->name in persist.c /
 * config_repl.c) and writes the resulting path into out_path. Does NOT touch
 * config_repl.c or persist.c -- these are hand-written fixture files so the
 * test exercises configcompare.c's OWN resolve-then-read logic, not a
 * different code path's. */
static void make_member_dir(const char* root, const char* name,
                            char out_path[512])
{
    snprintf(out_path, 512, "%s/%s", root, name);
    TEST_ASSERT_EQUAL_INT(0, mkdir(out_path, 0700));
    char conf_dir[560];
    snprintf(conf_dir, sizeof(conf_dir), "%s/conf", out_path);
    TEST_ASSERT_EQUAL_INT(0, mkdir(conf_dir, 0700));
}

static void write_conf_current(const char* member_path, const char* hexsuffix)
{
    char ptr_path[600];
    snprintf(ptr_path, sizeof(ptr_path), "%s/conf/current", member_path);
    FILE* f = fopen(ptr_path, "w");
    TEST_ASSERT_NOT_NULL(f);
    fprintf(f, "cluster.bin.%s\n", hexsuffix);
    fclose(f);
}

static void write_conf_blob(const char* member_path, const char* hexsuffix,
                            const uint8_t* bytes, size_t len)
{
    char blob_path[600];
    snprintf(blob_path, sizeof(blob_path), "%s/conf/cluster.bin.%s",
             member_path, hexsuffix);
    FILE* f = fopen(blob_path, "wb");
    TEST_ASSERT_NOT_NULL(f);
    if (len > 0)
        TEST_ASSERT_EQUAL_INT((int)len, (int)fwrite(bytes, 1, len, f));
    fclose(f);
}

/* Full happy-path member: dir + conf/current + the versioned blob it
 * points at. */
static void setup_member_ok(const char* root, const char* name,
                            const char* hexsuffix, const uint8_t* bytes,
                            size_t len, char out_path[512])
{
    make_member_dir(root, name, out_path);
    write_conf_current(out_path, hexsuffix);
    write_conf_blob(out_path, hexsuffix, bytes, len);
}

static void test_two_members_identical_config_reports_identical(void)
{
    fresh_dir();
    const uint8_t data[] = "identical config bytes for both members";

    char m0[512], m1[512];
    setup_member_ok(g_dir, "m0", "aaaaaaaaaaaa", data, sizeof(data) - 1, m0);
    setup_member_ok(g_dir, "m1", "bbbbbbbbbbbb", data, sizeof(data) - 1, m1);

    const char* paths[2] = { m0, m1 };
    configcompare_report_t rep;
    int rc = configcompare_paths(paths, 2, stdout, &rep);

    TEST_ASSERT_EQUAL_INT(0, rc);
    TEST_ASSERT_EQUAL_INT(1, rep.all_present);
    TEST_ASSERT_EQUAL_INT(1, rep.all_identical);
    TEST_ASSERT_EQUAL_INT(-1, rep.first_divergent_index);
    cleanup_dir();
}

static void test_two_members_differing_config_reports_divergent(void)
{
    fresh_dir();
    const uint8_t data0[] = "config bytes version A";
    const uint8_t data1[] = "config bytes version B, quite different";

    char m0[512], m1[512];
    setup_member_ok(g_dir, "m0", "aaaaaaaaaaaa", data0, sizeof(data0) - 1, m0);
    setup_member_ok(g_dir, "m1", "bbbbbbbbbbbb", data1, sizeof(data1) - 1, m1);

    const char* paths[2] = { m0, m1 };
    configcompare_report_t rep;
    int rc = configcompare_paths(paths, 2, stdout, &rep);

    TEST_ASSERT_EQUAL_INT(1, rc);
    TEST_ASSERT_EQUAL_INT(1, rep.all_present);
    TEST_ASSERT_EQUAL_INT(0, rep.all_identical);
    TEST_ASSERT_EQUAL_INT(1, rep.first_divergent_index);
    cleanup_dir();
}

/* A member with no conf/current pointer file at all must be reported as
 * unreadable (read_rc != 0), never silently folded into "identical" or
 * "divergent" against the two members that DO agree. */
static void test_missing_conf_current_reported_unreadable_not_divergent(void)
{
    fresh_dir();
    const uint8_t data[] = "shared config bytes across the healthy members";

    char m0[512], m1[512], m2[512];
    setup_member_ok(g_dir, "m0", "aaaaaaaaaaaa", data, sizeof(data) - 1, m0);
    /* m1: conf/ dir exists but conf/current was never written. */
    make_member_dir(g_dir, "m1", m1);
    setup_member_ok(g_dir, "m2", "cccccccccccc", data, sizeof(data) - 1, m2);

    const char* paths[3] = { m0, m1, m2 };
    configcompare_report_t rep;
    int rc = configcompare_paths(paths, 3, stdout, &rep);

    TEST_ASSERT_LESS_THAN_INT(0, rc);
    TEST_ASSERT_EQUAL_INT(0, rep.read_rc[0]);
    TEST_ASSERT_NOT_EQUAL(0, rep.read_rc[1]);
    TEST_ASSERT_EQUAL_INT(0, rep.all_present);
    cleanup_dir();
}

/* A member whose conf/current points at a versioned file that does not
 * exist on disk gets the same "unreadable" treatment as a missing pointer
 * file -- neither is evidence of matching or mismatching configuration. */
static void test_current_points_to_missing_versioned_file_reported_unreadable(void)
{
    fresh_dir();
    const uint8_t data[] = "shared config bytes, dangling pointer case";

    char m0[512], m1[512];
    setup_member_ok(g_dir, "m0", "aaaaaaaaaaaa", data, sizeof(data) - 1, m0);
    /* m1: conf/current points at cluster.bin.dddddddddddd, but that
     * versioned file was never written. */
    make_member_dir(g_dir, "m1", m1);
    write_conf_current(m1, "dddddddddddd");

    const char* paths[2] = { m0, m1 };
    configcompare_report_t rep;
    int rc = configcompare_paths(paths, 2, stdout, &rep);

    TEST_ASSERT_LESS_THAN_INT(0, rc);
    TEST_ASSERT_EQUAL_INT(0, rep.read_rc[0]);
    TEST_ASSERT_NOT_EQUAL(0, rep.read_rc[1]);
    cleanup_dir();
}

/* Basic determinism sanity check: comparing the same two byte-identical
 * files twice in a row yields the same hash both times. */
static void test_repeated_comparison_of_identical_files_is_deterministic(void)
{
    fresh_dir();
    const uint8_t data[] = "deterministic hash check bytes, fixed content";

    char m0[512], m1[512];
    setup_member_ok(g_dir, "m0", "aaaaaaaaaaaa", data, sizeof(data) - 1, m0);
    setup_member_ok(g_dir, "m1", "bbbbbbbbbbbb", data, sizeof(data) - 1, m1);

    const char* paths[2] = { m0, m1 };
    configcompare_report_t rep1, rep2;
    int rc1 = configcompare_paths(paths, 2, NULL, &rep1);
    int rc2 = configcompare_paths(paths, 2, NULL, &rep2);

    TEST_ASSERT_EQUAL_INT(0, rc1);
    TEST_ASSERT_EQUAL_INT(0, rc2);
    TEST_ASSERT_EQUAL_INT(0, memcmp(rep1.sha256[0], rep2.sha256[0], 32));
    TEST_ASSERT_EQUAL_INT(0, memcmp(rep1.sha256[1], rep2.sha256[1], 32));
    cleanup_dir();
}

/* Fewer than two members means there is nothing to compare -- a negative
 * errno, not a degenerate "identical" verdict. */
static void test_n_less_than_2_returns_negative_errno(void)
{
    const char* one_path[1] = { "/tmp/xce_configcompare_irrelevant" };
    configcompare_report_t rep;

    int rc0 = configcompare_paths(NULL, 0, NULL, &rep);
    TEST_ASSERT_LESS_THAN_INT(0, rc0);

    int rc1 = configcompare_paths(one_path, 1, NULL, &rep);
    TEST_ASSERT_LESS_THAN_INT(0, rc1);
}

void test_configcompare(void)
{
    UnitySetTestFile(__FILE__);
    RUN_TEST(test_two_members_identical_config_reports_identical);
    RUN_TEST(test_two_members_differing_config_reports_divergent);
    RUN_TEST(test_missing_conf_current_reported_unreadable_not_divergent);
    RUN_TEST(test_current_points_to_missing_versioned_file_reported_unreadable);
    RUN_TEST(test_repeated_comparison_of_identical_files_is_deterministic);
    RUN_TEST(test_n_less_than_2_returns_negative_errno);
}