/* SPDX-License-Identifier: Apache-2.0 */

/**
 * Copyright 2026 Thorsten Töpper
 *
 * For now working with gdbm, which is to my knowledge ported to every
 * important OS (GNU, BSD, UNIX (AIX, MacOS), Windows) and probably also
 * many of the less spread ones.
 *
 * This key value storage contains the processable filesystem entries,
 * meaning files and directories and whether they have been processed.
 *
 * The key is the path and fsentry name.
 *
 * The value a two byte char array with the first representing true or
 * false via 'T' or 'F', the second the type directory 'D', file 'F' or
 * '\0' if unknown.
 *
 * The unknown type should never show up.
 *
 * @file kv_manager.c
 *
 * vim:ts=4:sw=4:expandtab
 */
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <errno.h>

#include <gdbm.h>

#include "kv_manager.h"
#include "trace_macros.h"
#include "options.h"


/*=========== DEFINES, CONSTANTS AND TYPES ===========*/

/*=========== GLOBAL VARIABLES ===========*/
GDBM_FILE gdbf;

/*=========== FUNCTIONS ===========*/
bool add_b_t_wrapped(char *key, bool value, char type, bool keep_original_type);

/**
 * Open the key value storage used by the manager
 *
 * @param fname filename of the storage, for in-memory place it on a tmpfs
 *
 * @return  0 on success
 *         -1 on wrong filename
 *         -2 on already open gdbm file
 *         -3 on failure when opening or creating the db file
 */
int kv_open_storage(const char *fname) {
    if (fname == NULL || fname[0] == '\0') {
        LOGERR("ERROR: No valid filename\n");
        return false;
    }

    if (gdbf != NULL) {
        LOGERR("ERROR: Already a gdbm opened not switching\n");
        return false;
    }

    /* Currently CLOEXEC is obsolete, as no exec calls are planned */
    gdbf = gdbm_open(fname, 0, ((option_clean_kv) ? GDBM_NEWDB : GDBM_WRCREAT) | GDBM_CLOEXEC | GDBM_XVERIFY, 0644, NULL);
    if (gdbf == NULL) {
        LOGERR("ERROR: Failed to open gdbm db: %s\n",
                gdbm_strerror(gdbm_errno));
        return false;
    }
    return true;
}

/**
 * Close the currently storage
 *
 * @return true on success or if no storage was open
 */
bool kv_close_storage() {
    if (gdbf == NULL) {
        DBGTRC("DEBUG: No gdbm file open\n");
        return true;
    }
    if (gdbm_close(gdbf) != 0) {
        /* Both gdbm_errno and errno are set, communicate the generic one */
        LOGERR("ERROR: Failed to close gdbm file correctly: %s (errno: %d)\n",
                gdbm_strerror(gdbm_errno), errno);
        return false;
    }
    gdbf = NULL;
    return true;
}

/**
 * Local function to be wrapped by inserting/modifying ones.
 *
 * @param key keystring
 * @param state the bool part of the value
 * @param type the fs entry type of the value
 * @param keep_original_type bool whether the type parameter should be set or not.
 *
 * @return true on success
 *         false on failure
 */
bool add_b_t_wrapped(char *key, bool state, char type, bool keep_original_type) {
    datum k, v;
    int fcall_rc;
    char s[3] = { 0, 0, 0 };

    if (key == NULL || key[0] == '\0') {
        LOGERR("ERROR: No key given.\n");
        return false;
    }

    k.dptr = key;
    k.dsize = (int)strlen(key)+1;

    v = gdbm_fetch(gdbf, k);

    if ((v.dptr == NULL) && (gdbm_errno != GDBM_ITEM_NOT_FOUND)) {
        LOGERR("ERROR: Failed to check key existence for key '%s': %s\n",
                key, gdbm_strerror(gdbm_errno));
        return false;
    }

    if (v.dptr == NULL) {
        v.dptr = s;
        v.dsize = 3;
    }

    v.dptr[0] = (state) ? 'T' : 'F';
    if (!keep_original_type) {
        v.dptr[1] = type;
    }

    fcall_rc = gdbm_store(gdbf, k, v, GDBM_REPLACE);

    if (v.dptr != s)
        free(v.dptr);

    if (fcall_rc < 0) {
        LOGERR("ERROR: Failed store value for key '%s': %s\n",
                key, strerror(gdbm_errno));
        return false;
    }

    return true;
}


/**
 * Add the entry for the given key. Replaces already existing keys
 *
 * @param state boolean
 * @param type additional single byte information
 *
 * @return true on success
 *         false on failure
 */
bool kv_add_bool_type(char *key, bool state, char type) {
    return add_b_t_wrapped(key, state, type, false);
}

/**
 * Key is stored with given boolean value. If a key already exists the value is changed
 * else a new key is inserted.
 *
 * @param key key to set
 * @param value value to set
 *
 * @return true on success
 *         false on failure
 */
bool kv_set_bool(char *key, bool value) {
    return add_b_t_wrapped(key, value, 0, true);
}

/**
 * Get the bool part of the stored information. CAUTION: First check separately whether key exists!
 *
 * @param key the key string
 * @return the bool part of the value
 */
bool kv_get_bool(char *key) {
    char *raw = kv_get_raw(key);
    bool rc;

    if (raw == NULL) {
        return false;
    }

    rc = (raw[0] == 'T') ? true : false;
    free(raw);
    return rc;
}

/**
 * Get the type part of the stored information. CAUTION: First check separately whether key exists!
 *
 * @param key the key string
 * @return the char represent the type
 */
char kv_get_type(char *key) {
    char rc;
    char *raw = kv_get_raw(key);

    if (raw == NULL) {
        return 0;
    }

    rc = raw[1];
    free(raw);
    return rc;
}


/**
 * Get the raw value. CAUTION: First check separately whether key exists!
 *
 * @param key the key string
 * @return NULL in case of error or no value stored
 *         pointer to a short array which needs to be freed after processment
 */
char *kv_get_raw(char *key) {
    datum k, v;

    if (key == NULL || key[0] == '\0') {
        LOGERR("ERROR: No key given.\n");
        return NULL;
    }

    k.dptr = key;
    k.dsize = (int)strlen(key)+1;

    v = gdbm_fetch(gdbf, k);

    if (v.dptr == NULL && gdbm_errno != GDBM_ITEM_NOT_FOUND) {
        LOGERR("ERROR: Failed to fetch value for key '%s': %s\n",
                key, gdbm_strerror(gdbm_errno));
    }

    return v.dptr;
}


/**
 * Simple check if there's data for the key
 *
 * @param key the keystring
 * @return bool whether entry exists
 */
bool kv_entry_exists(char *key) {
    datum k;

    if (key == NULL || key[0] == '\0') {
        LOGERR("ERROR: No key given.\n");
        return false;
    }

    k.dptr = key;
    k.dsize = (int)strlen(key)+1;

    if (gdbm_exists(gdbf, k) == 1) {
        return true;
    }
    if (gdbm_errno != GDBM_NO_ERROR) {
        LOGERR("ERROR: Failed to verify existence of entry for key '%s': %s\n",
                key, gdbm_strerror(gdbm_errno));
    }
    return false;
}

/**
 * Wrapper to get the first key from the storage
 * @return pointer to a key, needs to be freed manually
 *         NULL in case of error or an empty storage
 */
char *kv_first_key() {
    datum k;
    k = gdbm_firstkey(gdbf);
    if ((k.dptr == NULL) && (gdbm_errno != GDBM_ITEM_NOT_FOUND)) {
        LOGERR("ERROR: Request for first key failed: %s\n",
                gdbm_strerror(gdbm_errno));
    }
    return k.dptr;
}

/**
 * Wrapper to get the next key stored
 * @return pointer to the key
 *         NULL if the end has been reached or an error occured
 */
char *kv_next_key(char *key) {
    datum k, nk;

    if (key == NULL || key[0] == '\0') {
        LOGERR("ERROR: No valid key given\n");
        return NULL;
    }

    k.dptr = key;
    k.dsize = (int)strlen(key)+1;

    nk = gdbm_nextkey(gdbf, k);

    if ((nk.dptr == NULL) && (gdbm_errno != GDBM_ITEM_NOT_FOUND)) {
        LOGERR("ERROR: Request for next key after '%s' failed: %s\n",
                key, gdbm_strerror(gdbm_errno));
    }

    return nk.dptr;
}

/**
 * Dump the storage data to the given output stream in incomplete JSON format
 *
 * @param out the file stream, if NULL stdout is used
 */
void kv_dump(FILE *out) {
    datum k, nk, v;

    if (out == NULL) {
        out = stdout;
    }

    k = gdbm_firstkey(gdbf);
    while (k.dptr != NULL) {
        v = gdbm_fetch(gdbf, k);

        if (v.dptr != NULL) {
            fprintf(out, "{k='%s', v='%c%c'},\n", k.dptr, v.dptr[0], v.dptr[1]);
            free(v.dptr);
        } else {
            if (gdbm_errno == GDBM_ITEM_NOT_FOUND) {
                fprintf(out, "{k='%s', v=NULL},}\n", k.dptr);
            } else {
                LOGERR("ERROR: Failed to get value for '%s': %s\n",
                        k.dptr, gdbm_strerror(gdbm_errno));
            }
        }

        nk = gdbm_nextkey(gdbf, k);
        free (k.dptr);
        k = nk;
    }
}