#include <platform.h>
#include <diagnose.h>
#include <logging.h>

#if defined(__MINGW32__) || !defined(LMDB)

int diagnose_main(
    ARG_UNUSED int argc, ARG_UNUSED const char *const *const argv)
{
    Log(LOG_LEVEL_ERR,
        "cf-check diagnose not available on this platform/build");
    return 1;
}

size_t diagnose_files(
    ARG_UNUSED const Seq *filenames,
    ARG_UNUSED Seq **corrupt,
    ARG_UNUSED bool foreground,
    ARG_UNUSED bool validate,
    ARG_UNUSED bool test_write)
{
    Log(LOG_LEVEL_INFO,
        "database diagnosis not available on this platform/build");
    return 0;
}

#else

#include <stdio.h>
#include <lmdump.h>
#include <lmdb.h>
#include <sys/wait.h>
#include <signal.h>
#include <utilities.h>
#include <sequence.h>
#include <alloc.h>
#include <string_lib.h>
#include <unistd.h>
#include <validate.h>
#include <openssl/rand.h>

/* NOTE: Must be in sync with LMDB_MAXSIZE in libpromises/dbm_lmdb.c. */
#ifndef LMDB_MAXSIZE
#define LMDB_MAXSIZE    104857600
#endif

#define CF_CHECK_CREATE_STRING(name) \
  #name,

static const char *CF_CHECK_STR[] = {
    CF_CHECK_RUN_CODES(CF_CHECK_CREATE_STRING)
};

static bool code_is_errno(int r)
{
    return (r > CF_CHECK_MAX);
}

// Better strerror, returns NULL if it doesn't know.
static const char *strerror_or_null(int r)
{
    const char *strerror_string = strerror(r);
    if (strerror_string == NULL)
    {
        return NULL;
    }

    const char *unknown = "Unknown error";
    if (strncmp(strerror_string, unknown, strlen(unknown)) == 0)
    {
        return NULL;
    }

    return strerror_string;
}

static int errno_to_code(int r)
{
    assert(r != 0);
    return r + CF_CHECK_MAX;
}

static int code_to_errno(int r)
{
    assert(code_is_errno(r));
    return r - CF_CHECK_MAX;
}

static const char *CF_CHECK_STRING(int code)
{
    static char unknown[1024];
    if (code <= 0 || code < CF_CHECK_MAX)
    {
        return CF_CHECK_STR[code];
    }
    else if (code_is_errno(code)) // code > CF_CHECK_MAX
    {
        code = code_to_errno(code);
        const char *str = strerror_or_null(code);
        if (str == NULL)
        {
            str = "Unknown";
        }
        snprintf(unknown, sizeof(unknown), "SYSTEM_ERROR %d - %s", code, str);
        return unknown;
    }
    return CF_CHECK_STR[CF_CHECK_UNKNOWN];
}

int signal_to_cf_check_code(int sig)
{
    switch (sig)
    {
    case SIGHUP:
        return CF_CHECK_SIGNAL_HANGUP;
    case SIGINT:
        return CF_CHECK_SIGNAL_INTERRUPT;
    case SIGQUIT:
        return CF_CHECK_SIGNAL_QUIT;
    case SIGILL:
        return CF_CHECK_SIGNAL_ILLEGAL_INSTRUCTION;
    case SIGTRAP:
        return CF_CHECK_SIGNAL_TRACE_TRAP;
    case SIGABRT:
        return CF_CHECK_SIGNAL_ABORT;
    case SIGFPE:
        return CF_CHECK_SIGNAL_FLOATING_POINT_EXCEPTION;
    case SIGKILL:
        return CF_CHECK_SIGNAL_KILL;
    case SIGBUS:
        return CF_CHECK_SIGNAL_BUS_ERROR;
    case SIGSEGV:
        return CF_CHECK_SIGNAL_SEGFAULT;
    case SIGSYS:
        return CF_CHECK_SIGNAL_NON_EXISTENT_SYSCALL;
    case SIGPIPE:
        return CF_CHECK_SIGNAL_INVALID_PIPE;
    case SIGALRM:
        return CF_CHECK_SIGNAL_TIMER_EXPIRED;
    case SIGTERM:
        return CF_CHECK_SIGNAL_TERMINATE;
    case SIGURG:
        return CF_CHECK_SIGNAL_URGENT_SOCKET_CONDITION;
    case SIGSTOP:
        return CF_CHECK_SIGNAL_STOP;
    case SIGTSTP:
        return CF_CHECK_SIGNAL_KEYBOARD_STOP;
    case SIGCONT:
        return CF_CHECK_SIGNAL_CONTINUE;
    case SIGCHLD:
        return CF_CHECK_SIGNAL_CHILD_STATUS_CHANGE;
    case SIGTTIN:
        return CF_CHECK_SIGNAL_BACKGROUND_READ_ATTEMPT;
    case SIGTTOU:
        return CF_CHECK_SIGNAL_BACKGROUND_WRITE_ATTEMPT;
    case SIGIO:
        return CF_CHECK_SIGNAL_IO_POSSIBLE_ON_DESCRIPTOR;
    case SIGXCPU:
        return CF_CHECK_SIGNAL_CPU_TIME_EXCEEDED;
    case SIGXFSZ:
        return CF_CHECK_SIGNAL_FILE_SIZE_EXCEEDED;
    case SIGVTALRM:
        return CF_CHECK_SIGNAL_VIRTUAL_TIME_ALARM;
    case SIGPROF:
        return CF_CHECK_SIGNAL_PROFILING_TIMER_ALARM;
    case SIGWINCH:
        return CF_CHECK_SIGNAL_WINDOW_SIZE_CHANGE;
    // Some signals are present on OS X / BSD but not Ubuntu 14, omitting:
    // case SIGEMT:
    //     return CF_CHECK_SIGNAL_EMULATE_INSTRUCTION;
    // case SIGINFO:
    //     return CF_CHECK_SIGNAL_STATUS_REQUEST;
    default:
        break;
    }
    return CF_CHECK_SIGNAL_OTHER;
}

int lmdb_errno_to_cf_check_code(int r)
{
    switch (r)
    {
    case 0:
        return CF_CHECK_OK;
    // LMDB-specific error codes:
    case MDB_KEYEXIST:
        return CF_CHECK_LMDB_KEY_EXISTS;
    case MDB_NOTFOUND:
        return CF_CHECK_LMDB_KEY_NOT_FOUND;
    case MDB_PAGE_NOTFOUND:
        return CF_CHECK_LMDB_PAGE_NOT_FOUND;
    case MDB_CORRUPTED:
        return CF_CHECK_LMDB_CORRUPT_PAGE;
    case MDB_PANIC:
        return CF_CHECK_LMDB_PANIC_FATAL_ERROR;
    case MDB_VERSION_MISMATCH:
        return CF_CHECK_LMDB_VERSION_MISMATCH;
    case MDB_INVALID:
        return CF_CHECK_LMDB_INVALID_DATABASE;
    case MDB_MAP_FULL:
        return CF_CHECK_LMDB_MAP_FULL;
    case MDB_DBS_FULL:
        return CF_CHECK_LMDB_DBS_FULL;
    case MDB_READERS_FULL:
        return CF_CHECK_LMDB_READERS_FULL;
    case MDB_TLS_FULL:
        return CF_CHECK_LMDB_TLS_KEYS_FULL;
    case MDB_TXN_FULL:
        return CF_CHECK_LMDB_TRANSACTION_FULL;
    case MDB_CURSOR_FULL:
        return CF_CHECK_LMDB_CURSOR_STACK_TOO_DEEP;
    case MDB_PAGE_FULL:
        return CF_CHECK_LMDB_PAGE_FULL;
    case MDB_MAP_RESIZED:
        return CF_CHECK_LMDB_MAP_RESIZE_BEYOND_SIZE;
    case MDB_INCOMPATIBLE:
        return CF_CHECK_LMDB_INCOMPATIBLE_OPERATION;
    case MDB_BAD_RSLOT:
        return CF_CHECK_LMDB_INVALID_REUSE_OF_READER_LOCKTABLE_SLOT;
    case MDB_BAD_TXN:
        return CF_CHECK_LMDB_BAD_OR_INVALID_TRANSACTION;
    case MDB_BAD_VALSIZE:
        return CF_CHECK_LMDB_WRONG_KEY_OR_VALUE_SIZE;
    // cf-check specific error codes:
    case CF_CHECK_ERRNO_VALIDATE_FAILED:
        return CF_CHECK_VALIDATE_FAILED;
    // Doesn't exist in earlier versions of LMDB:
    // case MDB_BAD_DBI:
    //     return CF_CHECK_LMDB_BAD_DBI;
    default:
        break;
    }
    const int s = errno_to_code(r);
    if (s == CF_CHECK_UNKNOWN)
    {
        return CF_CHECK_LMDUMP_UNKNOWN_ERROR;
    }
    return s;
}

void report_mdb_error(const char *db_file, const char *op, int rc)
{
    Log(LOG_LEVEL_ERR, "%s: %s error(%d): %s\n",
        db_file, op, rc, mdb_strerror(rc));
}

static int diagnose(const char *path, bool temporary_redirect, bool validate)
{
    // At this point we are already forked, we just need to decide 2 things:
    // * Should output be redirected (to prevent spam)?
    // * Which inner diagnose / validation function should be called?
    int ret;
    if (validate)
    {
        // --validate has meaningful output, so we don't want to redirect
        // regardless of whether it's foreground or forked.
        ret = CFCheck_Validate(path);
    }
    else if (temporary_redirect)
    {
        // --no-fork mode: temporarily redirect output to /dev/null & restore
        // Only done when necessary as it might not be so portable (/dev/fd)
        int saved_stdout = dup(STDOUT_FILENO);
        FILE *const f_result = freopen("/dev/null", "w", stdout);
        if (f_result == NULL)
        {
            return errno;
        }
        assert(f_result == stdout);
        ret = lmdump(LMDUMP_VALUES_ASCII, path);

        fflush(stdout);
        dup2(saved_stdout, STDOUT_FILENO);
    }
    else
    {
        // Normal mode: redirect to /dev/null permanently (forked process)
        FILE *const f_result = freopen("/dev/null", "w", stdout);
        if (f_result == NULL)
        {
            return errno;
        }
        assert(f_result == stdout);
        fclose(f_result);
        ret = lmdump(LMDUMP_VALUES_ASCII, path);
    }
    return lmdb_errno_to_cf_check_code(ret);
}

static int diagnose_write(const char *path)
{
    MDB_env *env = NULL;
    MDB_txn *txn = NULL;
    MDB_dbi dbi;
    bool close_dbi = false;
    MDB_cursor *cursor = NULL;

    /* We need to initialize these to NULL here so that we can safely call
     * free() on them in cleanup. */
    MDB_val new_key, new_data;
    new_key.mv_data = NULL;
    new_data.mv_data = NULL;

    int ret = 0;
    int rc;

    Log(LOG_LEVEL_INFO, "Trying to write data into '%s'", path);

    rc = mdb_env_create(&env);
    if (rc != MDB_SUCCESS)
    {
        ret = rc;
        report_mdb_error(path, "mdb_env_create", rc);
        goto cleanup;
    }

    rc = mdb_env_open(env, path, MDB_NOSUBDIR, 0600);
    if (rc != MDB_SUCCESS)
    {
        ret = rc;
        report_mdb_error(path, "mdb_env_open", rc);
        goto cleanup;
    }

    rc = mdb_txn_begin(env, NULL, 0, &txn);
    if (rc != MDB_SUCCESS)
    {
        ret = rc;
        report_mdb_error(path, "mdb_txn_begin", rc);
        goto cleanup;
    }

    rc = mdb_dbi_open(txn, NULL, 0, &dbi);
    if (rc != MDB_SUCCESS)
    {
        ret = rc;
        report_mdb_error(path, "mdb_dbi_open", rc);
        goto cleanup;
    }
    else
    {
        close_dbi = true;
    }

    rc = mdb_cursor_open(txn, dbi, &cursor);
    if (rc != MDB_SUCCESS)
    {
        ret = rc;
        report_mdb_error(path, "mdb_cursor_open", rc);
        goto cleanup;
    }

    MDB_val key, data;
    rc = mdb_cursor_get(cursor, &key, &data, MDB_NEXT);
    /* MDB_NOTFOUND => no more data */
    if (rc == MDB_NOTFOUND)
    {
        Log(LOG_LEVEL_INFO,
            "'%s' is empty, no data to use as a template, cannot test writing",
            path);
        ret = 0;
        goto cleanup;
    }
    else if (rc != MDB_SUCCESS)
    {
        report_mdb_error(path, "mdb_cursor_get", rc);
        ret = rc;
        goto cleanup;
    }
    /* else */
    new_key.mv_size = key.mv_size;
    new_data.mv_size = data.mv_size;
    new_key.mv_data = xmalloc(new_key.mv_size);
    new_data.mv_data = xmalloc(new_data.mv_size);

    rc = RAND_bytes((char *) new_key.mv_data, new_key.mv_size);
    if (rc != 1)
    {
        Log(LOG_LEVEL_ERR, "Failed to generate random key data");
        ret = -1;
        goto cleanup;
    }
    rc = RAND_bytes((char *) new_data.mv_data, new_data.mv_size);
    if (rc != 1)
    {
        Log(LOG_LEVEL_ERR, "Failed to generate random value data");
        ret = -1;
        goto cleanup;
    }
    rc = mdb_put(txn, dbi, &new_key, &new_data, 0);
    if (rc != MDB_SUCCESS)
    {
        report_mdb_error(path, "mdb_put", rc);
        Log(LOG_LEVEL_ERR, "Failed to write new data into '%s'", path);
        ret = rc;
        goto cleanup;
    }

    rc = mdb_txn_commit(txn);
    if (rc != MDB_SUCCESS)
    {
        report_mdb_error(path, "mdb_txn_commit", rc);
        Log(LOG_LEVEL_ERR, "Failed to commit new data into '%s'", path);
        ret = rc;
        goto cleanup;
    }
    txn = NULL;

    mdb_close(env, dbi);
    close_dbi = false;

    rc = mdb_txn_begin(env, NULL, 0, &txn);
    if (rc != MDB_SUCCESS)
    {
        ret = rc;
        report_mdb_error(path, "mdb_txn_begin", rc);
        goto cleanup;
    }

    rc = mdb_dbi_open(txn, NULL, 0, &dbi);
    if (rc != MDB_SUCCESS)
    {
        ret = rc;
        report_mdb_error(path, "mdb_dbi_open", rc);
        goto cleanup;
    }
    else
    {
        close_dbi = true;
    }

    rc = mdb_del(txn, dbi, &new_key, NULL);
    if (rc != MDB_SUCCESS)
    {
        report_mdb_error(path, "mdb_del", rc);
        Log(LOG_LEVEL_ERR, "Failed to delete new data from '%s'", path);
        ret = rc;
        goto cleanup;
    }

    rc = mdb_txn_commit(txn);
    if (rc != MDB_SUCCESS)
    {
        report_mdb_error(path, "mdb_txn_commit", rc);
        Log(LOG_LEVEL_ERR, "Failed to commit removal of new data from '%s'", path);
        ret = rc;
        goto cleanup;
    }
    txn = NULL;

    mdb_close(env, dbi);
    close_dbi = false;

  cleanup:
    free(new_key.mv_data);
    free(new_data.mv_data);

    if (cursor != NULL)
    {
        mdb_cursor_close(cursor);
    }
    if (close_dbi)
    {
        mdb_close(env, dbi);
    }
    if (txn != NULL)
    {
        mdb_txn_abort(txn);
    }
    if (env != NULL)
    {
        mdb_env_close(env);
    }

    ret = lmdb_errno_to_cf_check_code(ret);
    return ret;
}

static int fork_and_diagnose(const char *path, bool validate, bool test_write)
{
    const pid_t child_pid = fork();
    if (child_pid == 0)
    {
        // Child
        /* The second argument is 'temporary_redirect' and we require a
         * temporary redirect if we want to test writability because that
         * produces output. */
        int r = diagnose(path, test_write, validate);
        if ((r == CF_CHECK_OK) && test_write)
        {
            r = diagnose_write(path);
        }
        exit(r);
    }
    else
    {
        // Parent
        int status;
        pid_t pid = waitpid(child_pid, &status, 0);
        if (pid != child_pid)
        {
            return CF_CHECK_PID_ERROR;
        }
        if (WIFEXITED(status) && WEXITSTATUS(status) != CF_CHECK_OK)
        {
            return WEXITSTATUS(status);
        }
        if (WIFSIGNALED(status))
        {
            return signal_to_cf_check_code(WTERMSIG(status));
        }
    }
    return CF_CHECK_OK;
}

static char *follow_symlink(const char *path)
{
    char target_buf[4096] = { 0 };
    const ssize_t r = readlink(path, target_buf, sizeof(target_buf));
    if (r < 0)
    {
        return NULL;
    }
    if ((size_t) r >= sizeof(target_buf))
    {
        Log(LOG_LEVEL_ERR, "Symlink target path too long: %s", path);
        return NULL;
    }
    target_buf[r] = '\0';
    return xstrdup(target_buf);
}

bool lmdb_file_needs_rotation(const char *file, int *usage)
{
    struct stat sb;
    if (stat(file, &sb) == 0)
    {
        int usage_pct = (((float) sb.st_size) / LMDB_MAXSIZE) * 100;
        if (usage != NULL)
        {
            *usage = usage_pct;
        }
        return (usage_pct >= 95);
    }
    else
    {
        Log(LOG_LEVEL_ERR, "Failed to stat() '%s' when checking usage: %s", file, GetErrorStr());
        return false;
    }
}

/**
 * @param[in]  filenames  DB files to diagnose/check
 * @param[out] corrupt    place to store the resulting sequence of corrupted
 *                        files or %NULL (to only get the number of corrupted
 *                        files)
 * @param[in]  foreground whether to run in foreground or fork (safer)
 * @param[in]  test_write whether to test writing into the DB
 * @return                the number of the corrupted files
 */
size_t diagnose_files(
    const Seq *filenames,
    Seq **corrupt,
    bool foreground,
    bool validate,
    bool test_write)
{
    size_t corruptions = 0;
    const size_t length = SeqLength(filenames);

    if (corrupt != NULL)
    {
        *corrupt = SeqNew(length, free);
    }

    for (size_t i = 0; i < length; ++i)
    {
        const char *filename = SeqAt(filenames, i);
        const char *symlink = NULL; // Only initialized because of gcc warning
        int r = 0; // Only initialized because of LGTM alert
        char *symlink_target = follow_symlink(filename);
        bool broken_symlink_handled = false;
        if (symlink_target != NULL)
        {
            symlink = filename;
            // If the LMDB file path is a symlink
            filename = symlink_target;
            if (access(symlink_target, F_OK) != 0)
            {
                // Symlink target file does not exist
                r = CF_CHECK_OK_DOES_NOT_EXIST;
                broken_symlink_handled = true;
            }
            // If this is not the case, continue repair as normal,
            // using the symlink target instead of the symlink in diagnose
            // and repair functions
        }
        if (broken_symlink_handled)
        {
            // The LMDB database was a broken symlink,
            // we don't need to do anything, agent will recreate it.
        }
        else if (foreground)
        {
            r = diagnose(filename, true, validate);
            if ((r == CF_CHECK_OK) && test_write)
            {
                r = diagnose_write(filename);
            }
        }
        else
        {
            r = fork_and_diagnose(filename, validate, test_write);
        }

        if (symlink_target != NULL)
        {
            int usage;
            bool needs_rotation = lmdb_file_needs_rotation(symlink_target, &usage);
            Log(LOG_LEVEL_INFO,
                "Status of '%s' -> '%s': %s [%d%% usage%s]\n",
                symlink,
                symlink_target,
                CF_CHECK_STRING(r),
                usage,
                needs_rotation ? ", needs rotation" : "");
        }
        else
        {
            int usage;
            bool needs_rotation = lmdb_file_needs_rotation(filename, &usage);
            Log(LOG_LEVEL_INFO,
                "Status of '%s': %s [%d%% usage%s]\n",
                filename,
                CF_CHECK_STRING(r),
                usage,
                needs_rotation ? ", needs rotation" : "");
        }


        if (r != CF_CHECK_OK && r != CF_CHECK_OK_DOES_NOT_EXIST)
        {
            ++corruptions;
            if (corrupt != NULL)
            {
                SeqAppend(*corrupt, xstrdup(filename));
            }
        }
        free(symlink_target);
    }
    if (corruptions == 0)
    {
        Log(LOG_LEVEL_INFO, "All %zu databases healthy", length);
    }
    else
    {
        Log(LOG_LEVEL_ERR,
            "Problems detected in %zu/%zu databases",
            corruptions,
            length);
    }
    return corruptions;
}

int diagnose_main(int argc, const char *const *const argv)
{
    size_t offset = 1;
    bool foreground = false;
    bool validate = false;
    bool test_write = false;
    for (int i = offset; i < argc && argv[i][0] == '-'; ++i)
    {
        if (StringMatchesOption(argv[i], "--no-fork", "-F"))
        {
            foreground = true;
            offset += 1;
        }
        else if (StringMatchesOption(argv[i], "--validate", "-v"))
        {
            validate = true;
            offset += 1;
        }
        else if (StringMatchesOption(argv[i], "--test-write", "-w"))
        {
            test_write = true;
            offset += 1;
        }
        else
        {
            assert(argv[i][0] == '-'); // For-loop condition
            Log(LOG_LEVEL_ERR, "Unrecognized option: '%s'", argv[i]);
            return 2;
        }
    }
    Seq *files = argv_to_lmdb_files(argc, argv, offset);
    if (files == NULL || SeqLength(files) == 0)
    {
        Log(LOG_LEVEL_ERR, "No database files to diagnose");
        return 1;
    }
    const int ret = diagnose_files(files, NULL, foreground, validate, test_write);
    SeqDestroy(files);
    return ret;
}

#endif