/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013, 2014 Damien P. George
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include "py/mpconfig.h"
#include "py/misc.h"
#include "py/runtime.h"

#if MICROPY_DEBUG_VERBOSE // print debugging info
#define DEBUG_PRINT (1)
#else // don't print debugging info
#define DEBUG_PRINT (0)
#define DEBUG_printf(...) (void)0
#endif

// Fixed empty map. Useful when need to call kw-receiving functions
// without any keywords from C, etc.
const mp_map_t mp_const_empty_map = {
 .all_keys_are_qstrs = 0,
 .is_fixed = 1,
 .is_ordered = 1,
 .used = 0,
 .alloc = 0,
 .table = NULL,
};

// This table of sizes is used to control the growth of hash tables.
// The first set of sizes are chosen so the allocation fits exactly in a
// 4-word GC block, and it's not so important for these small values to be
// prime. The latter sizes are prime and increase at an increasing rate.
STATIC const uint16_t hash_allocation_sizes[] = {
 0, 2, 4, 6, 8, 10, 12, // +2
 17, 23, 29, 37, 47, 59, 73, // *1.25
 97, 127, 167, 223, 293, 389, 521, 691, 919, 1223, 1627, 2161, // *1.33
 3229, 4831, 7243, 10861, 16273, 24407, 36607, 54907, // *1.5
};

STATIC size_t get_hash_alloc_greater_or_equal_to(size_t x) {
 for (size_t i = 0; i < MP_ARRAY_SIZE(hash_allocation_sizes); i++) {
 if (hash_allocation_sizes[i] >= x) {
 return hash_allocation_sizes[i];
 }
 }
 // ran out of primes in the table!
 // return something sensible, at least make it odd
 return (x + x / 2) | 1;
}

/******************************************************************************/
/* map */

void mp_map_init(mp_map_t *map, size_t n) {
 if (n == 0) {
 map->alloc = 0;
 map->table = NULL;
 } else {
 map->alloc = n;
 map->table = m_new0(mp_map_elem_t, map->alloc);
 }
 map->used = 0;
 map->all_keys_are_qstrs = 1;
 map->is_fixed = 0;
 map->is_ordered = 0;
}

void mp_map_init_fixed_table(mp_map_t *map, size_t n, const mp_obj_t *table) {
 map->alloc = n;
 map->used = n;
 map->all_keys_are_qstrs = 1;
 map->is_fixed = 1;
 map->is_ordered = 1;
 map->table = (mp_map_elem_t *)table;
}

// Differentiate from mp_map_clear() - semantics is different
void mp_map_deinit(mp_map_t *map) {
 if (!map->is_fixed) {
 m_del(mp_map_elem_t, map->table, map->alloc);
 }
 map->used = map->alloc = 0;
}

void mp_map_clear(mp_map_t *map) {
 if (!map->is_fixed) {
 m_del(mp_map_elem_t, map->table, map->alloc);
 }
 map->alloc = 0;
 map->used = 0;
 map->all_keys_are_qstrs = 1;
 map->is_fixed = 0;
 map->table = NULL;
}

STATIC void mp_map_rehash(mp_map_t *map) {
 size_t old_alloc = map->alloc;
 size_t new_alloc = get_hash_alloc_greater_or_equal_to(map->alloc + 1);
 DEBUG_printf("mp_map_rehash(%p): " UINT_FMT " -> " UINT_FMT "\n", map, old_alloc, new_alloc);
 mp_map_elem_t *old_table = map->table;
 mp_map_elem_t *new_table = m_new0(mp_map_elem_t, new_alloc);
 // If we reach this point, table resizing succeeded, now we can edit the old map.
 map->alloc = new_alloc;
 map->used = 0;
 map->all_keys_are_qstrs = 1;
 map->table = new_table;
 for (size_t i = 0; i < old_alloc; i++) {
 if (old_table[i].key != MP_OBJ_NULL && old_table[i].key != MP_OBJ_SENTINEL) {
 mp_map_lookup(map, old_table[i].key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = old_table[i].value;
 }
 }
 m_del(mp_map_elem_t, old_table, old_alloc);
}

// MP_MAP_LOOKUP behaviour:
// - returns NULL if not found, else the slot it was found in with key,value non-null
// MP_MAP_LOOKUP_ADD_IF_NOT_FOUND behaviour:
// - returns slot, with key non-null and value=MP_OBJ_NULL if it was added
// MP_MAP_LOOKUP_REMOVE_IF_FOUND behaviour:
// - returns NULL if not found, else the slot if was found in with key null and value non-null
mp_map_elem_t *mp_map_lookup(mp_map_t *map, mp_obj_t index, mp_map_lookup_kind_t lookup_kind) {
 // If the map is a fixed array then we must only be called for a lookup
 assert(!map->is_fixed || lookup_kind == MP_MAP_LOOKUP);

 // Work out if we can compare just pointers
 bool compare_only_ptrs = map->all_keys_are_qstrs;
 if (compare_only_ptrs) {
 if (mp_obj_is_qstr(index)) {
 // Index is a qstr, so can just do ptr comparison.
 } else if (mp_obj_is_type(index, &mp_type_str)) {
 // Index is a non-interned string.
 // We can either intern the string, or force a full equality comparison.
 // We chose the latter, since interning costs time and potentially RAM,
 // and it won't necessarily benefit subsequent calls because these calls
 // most likely won't pass the newly-interned string.
 compare_only_ptrs = false;
 } else if (lookup_kind != MP_MAP_LOOKUP_ADD_IF_NOT_FOUND) {
 // If we are not adding, then we can return straight away a failed
 // lookup because we know that the index will never be found.
 return NULL;
 }
 }

 // if the map is an ordered array then we must do a brute force linear search
 if (map->is_ordered) {
 for (mp_map_elem_t *elem = &map->table[0], *top = &map->table[map->used]; elem < top; elem++) {
 if (elem->key == index || (!compare_only_ptrs && mp_obj_equal(elem->key, index))) {
 #if MICROPY_PY_COLLECTIONS_ORDEREDDICT
 if (MP_UNLIKELY(lookup_kind == MP_MAP_LOOKUP_REMOVE_IF_FOUND)) {
 // remove the found element by moving the rest of the array down
 mp_obj_t value = elem->value;
 --map->used;
 memmove(elem, elem + 1, (top - elem - 1) * sizeof(*elem));
 // put the found element after the end so the caller can access it if needed
 // note: caller must NULL the value so the GC can clean up (e.g. see dict_get_helper).
 elem = &map->table[map->used];
 elem->key = MP_OBJ_NULL;
 elem->value = value;
 }
 #endif
 return elem;
 }
 }
 #if MICROPY_PY_COLLECTIONS_ORDEREDDICT
 if (MP_LIKELY(lookup_kind != MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)) {
 return NULL;
 }
 if (map->used == map->alloc) {
 // TODO: Alloc policy
 map->alloc += 4;
 map->table = m_renew(mp_map_elem_t, map->table, map->used, map->alloc);
 mp_seq_clear(map->table, map->used, map->alloc, sizeof(*map->table));
 }
 mp_map_elem_t *elem = map->table + map->used++;
 elem->key = index;
 if (!mp_obj_is_qstr(index)) {
 map->all_keys_are_qstrs = 0;
 }
 return elem;
 #else
 return NULL;
 #endif
 }

 // map is a hash table (not an ordered array), so do a hash lookup

 if (map->alloc == 0) {
 if (lookup_kind == MP_MAP_LOOKUP_ADD_IF_NOT_FOUND) {
 mp_map_rehash(map);
 } else {
 return NULL;
 }
 }

 // get hash of index, with fast path for common case of qstr
 mp_uint_t hash;
 if (mp_obj_is_qstr(index)) {
 hash = qstr_hash(MP_OBJ_QSTR_VALUE(index));
 } else {
 hash = MP_OBJ_SMALL_INT_VALUE(mp_unary_op(MP_UNARY_OP_HASH, index));
 }

 size_t pos = hash % map->alloc;
 size_t start_pos = pos;
 mp_map_elem_t *avail_slot = NULL;
 for (;;) {
 mp_map_elem_t *slot = &map->table[pos];
 if (slot->key == MP_OBJ_NULL) {
 // found NULL slot, so index is not in table
 if (lookup_kind == MP_MAP_LOOKUP_ADD_IF_NOT_FOUND) {
 map->used += 1;
 if (avail_slot == NULL) {
 avail_slot = slot;
 }
 avail_slot->key = index;
 avail_slot->value = MP_OBJ_NULL;
 if (!mp_obj_is_qstr(index)) {
 map->all_keys_are_qstrs = 0;
 }
 return avail_slot;
 } else {
 return NULL;
 }
 } else if (slot->key == MP_OBJ_SENTINEL) {
 // found deleted slot, remember for later
 if (avail_slot == NULL) {
 avail_slot = slot;
 }
 } else if (slot->key == index || (!compare_only_ptrs && mp_obj_equal(slot->key, index))) {
 // found index
 // Note: CPython does not replace the index; try x={True:'true'};x[1]='one';x
 if (lookup_kind == MP_MAP_LOOKUP_REMOVE_IF_FOUND) {
 // delete element in this slot
 map->used--;
 if (map->table[(pos + 1) % map->alloc].key == MP_OBJ_NULL) {
 // optimisation if next slot is empty
 slot->key = MP_OBJ_NULL;
 } else {
 slot->key = MP_OBJ_SENTINEL;
 }
 // keep slot->value so that caller can access it if needed
 }
 return slot;
 }

 // not yet found, keep searching in this table
 pos = (pos + 1) % map->alloc;

 if (pos == start_pos) {
 // search got back to starting position, so index is not in table
 if (lookup_kind == MP_MAP_LOOKUP_ADD_IF_NOT_FOUND) {
 if (avail_slot != NULL) {
 // there was an available slot, so use that
 map->used++;
 avail_slot->key = index;
 avail_slot->value = MP_OBJ_NULL;
 if (!mp_obj_is_qstr(index)) {
 map->all_keys_are_qstrs = 0;
 }
 return avail_slot;
 } else {
 // not enough room in table, rehash it
 mp_map_rehash(map);
 // restart the search for the new element
 start_pos = pos = hash % map->alloc;
 }
 } else {
 return NULL;
 }
 }
 }
}

/******************************************************************************/
/* set */

#if MICROPY_PY_BUILTINS_SET

void mp_set_init(mp_set_t *set, size_t n) {
 set->alloc = n;
 set->used = 0;
 set->table = m_new0(mp_obj_t, set->alloc);
}

STATIC void mp_set_rehash(mp_set_t *set) {
 size_t old_alloc = set->alloc;
 mp_obj_t *old_table = set->table;
 set->alloc = get_hash_alloc_greater_or_equal_to(set->alloc + 1);
 set->used = 0;
 set->table = m_new0(mp_obj_t, set->alloc);
 for (size_t i = 0; i < old_alloc; i++) {
 if (old_table[i] != MP_OBJ_NULL && old_table[i] != MP_OBJ_SENTINEL) {
 mp_set_lookup(set, old_table[i], MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
 }
 }
 m_del(mp_obj_t, old_table, old_alloc);
}

mp_obj_t mp_set_lookup(mp_set_t *set, mp_obj_t index, mp_map_lookup_kind_t lookup_kind) {
 // Note: lookup_kind can be MP_MAP_LOOKUP_ADD_IF_NOT_FOUND_OR_REMOVE_IF_FOUND which
 // is handled by using bitwise operations.

 if (set->alloc == 0) {
 if (lookup_kind & MP_MAP_LOOKUP_ADD_IF_NOT_FOUND) {
 mp_set_rehash(set);
 } else {
 return MP_OBJ_NULL;
 }
 }
 mp_uint_t hash = MP_OBJ_SMALL_INT_VALUE(mp_unary_op(MP_UNARY_OP_HASH, index));
 size_t pos = hash % set->alloc;
 size_t start_pos = pos;
 mp_obj_t *avail_slot = NULL;
 for (;;) {
 mp_obj_t elem = set->table[pos];
 if (elem == MP_OBJ_NULL) {
 // found NULL slot, so index is not in table
 if (lookup_kind & MP_MAP_LOOKUP_ADD_IF_NOT_FOUND) {
 if (avail_slot == NULL) {
 avail_slot = &set->table[pos];
 }
 set->used++;
 *avail_slot = index;
 return index;
 } else {
 return MP_OBJ_NULL;
 }
 } else if (elem == MP_OBJ_SENTINEL) {
 // found deleted slot, remember for later
 if (avail_slot == NULL) {
 avail_slot = &set->table[pos];
 }
 } else if (mp_obj_equal(elem, index)) {
 // found index
 if (lookup_kind & MP_MAP_LOOKUP_REMOVE_IF_FOUND) {
 // delete element
 set->used--;
 if (set->table[(pos + 1) % set->alloc] == MP_OBJ_NULL) {
 // optimisation if next slot is empty
 set->table[pos] = MP_OBJ_NULL;
 } else {
 set->table[pos] = MP_OBJ_SENTINEL;
 }
 }
 return elem;
 }

 // not yet found, keep searching in this table
 pos = (pos + 1) % set->alloc;

 if (pos == start_pos) {
 // search got back to starting position, so index is not in table
 if (lookup_kind & MP_MAP_LOOKUP_ADD_IF_NOT_FOUND) {
 if (avail_slot != NULL) {
 // there was an available slot, so use that
 set->used++;
 *avail_slot = index;
 return index;
 } else {
 // not enough room in table, rehash it
 mp_set_rehash(set);
 // restart the search for the new element
 start_pos = pos = hash % set->alloc;
 }
 } else {
 return MP_OBJ_NULL;
 }
 }
 }
}

mp_obj_t mp_set_remove_first(mp_set_t *set) {
 for (size_t pos = 0; pos < set->alloc; pos++) {
 if (mp_set_slot_is_filled(set, pos)) {
 mp_obj_t elem = set->table[pos];
 // delete element
 set->used--;
 if (set->table[(pos + 1) % set->alloc] == MP_OBJ_NULL) {
 // optimisation if next slot is empty
 set->table[pos] = MP_OBJ_NULL;
 } else {
 set->table[pos] = MP_OBJ_SENTINEL;
 }
 return elem;
 }
 }
 return MP_OBJ_NULL;
}

void mp_set_clear(mp_set_t *set) {
 m_del(mp_obj_t, set->table, set->alloc);
 set->alloc = 0;
 set->used = 0;
 set->table = NULL;
}

#endif // MICROPY_PY_BUILTINS_SET

#if defined(DEBUG_PRINT) && DEBUG_PRINT
void mp_map_dump(mp_map_t *map) {
 for (size_t i = 0; i < map->alloc; i++) {
 if (map->table[i].key != MP_OBJ_NULL) {
 mp_obj_print(map->table[i].key, PRINT_REPR);
 } else {
 DEBUG_printf("(nil)");
 }
 DEBUG_printf(": %p\n", map->table[i].value);
 }
 DEBUG_printf("---\n");
}
#endif