/*
 * 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 <assert.h>
#include <string.h>
#include <stdio.h>

#include "py/mpstate.h"
#include "py/qstr.h"
#include "py/gc.h"
#include "py/runtime.h"

// NOTE: we are using linear arrays to store and search for qstr's (unique strings, interned strings)
// ultimately we will replace this with a static hash table of some kind
// also probably need to include the length in the string data, to allow null bytes in the string

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

// A qstr is an index into the qstr pool.
// The data for a qstr contains (hash, length, data):
// - hash (configurable number of bytes)
// - length (configurable number of bytes)
// - data ("length" number of bytes)
// - 0円 terminated (so they can be printed using printf)

#if MICROPY_QSTR_BYTES_IN_HASH == 1
 #define Q_HASH_MASK (0xff)
 #define Q_GET_HASH(q) ((mp_uint_t)(q)[0])
 #define Q_SET_HASH(q, hash) do { (q)[0] = (hash); } while (0)
#elif MICROPY_QSTR_BYTES_IN_HASH == 2
 #define Q_HASH_MASK (0xffff)
 #define Q_GET_HASH(q) ((mp_uint_t)(q)[0] | ((mp_uint_t)(q)[1] << 8))
 #define Q_SET_HASH(q, hash) do { (q)[0] = (hash); (q)[1] = (hash) >> 8; } while (0)
#else
 #error unimplemented qstr hash decoding
#endif
#define Q_GET_ALLOC(q) (MICROPY_QSTR_BYTES_IN_HASH + MICROPY_QSTR_BYTES_IN_LEN + Q_GET_LENGTH(q) + 1)
#define Q_GET_DATA(q) ((q) + MICROPY_QSTR_BYTES_IN_HASH + MICROPY_QSTR_BYTES_IN_LEN)
#if MICROPY_QSTR_BYTES_IN_LEN == 1
 #define Q_GET_LENGTH(q) ((q)[MICROPY_QSTR_BYTES_IN_HASH])
 #define Q_SET_LENGTH(q, len) do { (q)[MICROPY_QSTR_BYTES_IN_HASH] = (len); } while (0)
#elif MICROPY_QSTR_BYTES_IN_LEN == 2
 #define Q_GET_LENGTH(q) ((q)[MICROPY_QSTR_BYTES_IN_HASH] | ((q)[MICROPY_QSTR_BYTES_IN_HASH + 1] << 8))
 #define Q_SET_LENGTH(q, len) do { (q)[MICROPY_QSTR_BYTES_IN_HASH] = (len); (q)[MICROPY_QSTR_BYTES_IN_HASH + 1] = (len) >> 8; } while (0)
#else
 #error unimplemented qstr length decoding
#endif

#if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
#define QSTR_ENTER() mp_thread_mutex_lock(&MP_STATE_VM(qstr_mutex), 1)
#define QSTR_EXIT() mp_thread_mutex_unlock(&MP_STATE_VM(qstr_mutex))
#else
#define QSTR_ENTER()
#define QSTR_EXIT()
#endif

// Initial number of entries for qstr pool, set so that the first dynamically
// allocated pool is twice this size. The value here must be <= MP_QSTRnumber_of.
#define MICROPY_ALLOC_QSTR_ENTRIES_INIT (10)

// this must match the equivalent function in makeqstrdata.py
mp_uint_t qstr_compute_hash(const byte *data, size_t len) {
 // djb2 algorithm; see http://www.cse.yorku.ca/~oz/hash.html
 mp_uint_t hash = 5381;
 for (const byte *top = data + len; data < top; data++) {
 hash = ((hash << 5) + hash) ^ (*data); // hash * 33 ^ data
 }
 hash &= Q_HASH_MASK;
 // Make sure that valid hash is never zero, zero means "hash not computed"
 if (hash == 0) {
 hash++;
 }
 return hash;
}

const qstr_pool_t mp_qstr_const_pool = {
 NULL, // no previous pool
 0, // no previous pool
 MICROPY_ALLOC_QSTR_ENTRIES_INIT,
 MP_QSTRnumber_of, // corresponds to number of strings in array just below
 {
 #ifndef NO_QSTR
#define QDEF(id, str) str,
 #include "genhdr/qstrdefs.generated.h"
#undef QDEF
 #endif
 },
};

#ifdef MICROPY_QSTR_EXTRA_POOL
extern const qstr_pool_t MICROPY_QSTR_EXTRA_POOL;
#define CONST_POOL MICROPY_QSTR_EXTRA_POOL
#else
#define CONST_POOL mp_qstr_const_pool
#endif

void qstr_init(void) {
 MP_STATE_VM(last_pool) = (qstr_pool_t *)&CONST_POOL; // we won't modify the const_pool since it has no allocated room left
 MP_STATE_VM(qstr_last_chunk) = NULL;

 #if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
 mp_thread_mutex_init(&MP_STATE_VM(qstr_mutex));
 #endif
}

STATIC const byte *find_qstr(qstr q) {
 // search pool for this qstr
 // total_prev_len==0 in the final pool, so the loop will always terminate
 qstr_pool_t *pool = MP_STATE_VM(last_pool);
 while (q < pool->total_prev_len) {
 pool = pool->prev;
 }
 return pool->qstrs[q - pool->total_prev_len];
}

// qstr_mutex must be taken while in this function
STATIC qstr qstr_add(const byte *q_ptr) {
 DEBUG_printf("QSTR: add hash=%d len=%d data=%.*s\n", Q_GET_HASH(q_ptr), Q_GET_LENGTH(q_ptr), Q_GET_LENGTH(q_ptr), Q_GET_DATA(q_ptr));

 // make sure we have room in the pool for a new qstr
 if (MP_STATE_VM(last_pool)->len >= MP_STATE_VM(last_pool)->alloc) {
 size_t new_alloc = MP_STATE_VM(last_pool)->alloc * 2;
 #ifdef MICROPY_QSTR_EXTRA_POOL
 // Put a lower bound on the allocation size in case the extra qstr pool has few entries
 new_alloc = MAX(MICROPY_ALLOC_QSTR_ENTRIES_INIT, new_alloc);
 #endif
 qstr_pool_t *pool = m_new_obj_var_maybe(qstr_pool_t, const char *, new_alloc);
 if (pool == NULL) {
 QSTR_EXIT();
 m_malloc_fail(new_alloc);
 }
 pool->prev = MP_STATE_VM(last_pool);
 pool->total_prev_len = MP_STATE_VM(last_pool)->total_prev_len + MP_STATE_VM(last_pool)->len;
 pool->alloc = new_alloc;
 pool->len = 0;
 MP_STATE_VM(last_pool) = pool;
 DEBUG_printf("QSTR: allocate new pool of size %d\n", MP_STATE_VM(last_pool)->alloc);
 }

 // add the new qstr
 MP_STATE_VM(last_pool)->qstrs[MP_STATE_VM(last_pool)->len++] = q_ptr;

 // return id for the newly-added qstr
 return MP_STATE_VM(last_pool)->total_prev_len + MP_STATE_VM(last_pool)->len - 1;
}

qstr qstr_find_strn(const char *str, size_t str_len) {
 // work out hash of str
 mp_uint_t str_hash = qstr_compute_hash((const byte *)str, str_len);

 // search pools for the data
 for (qstr_pool_t *pool = MP_STATE_VM(last_pool); pool != NULL; pool = pool->prev) {
 for (const byte **q = pool->qstrs, **q_top = pool->qstrs + pool->len; q < q_top; q++) {
 if (Q_GET_HASH(*q) == str_hash && Q_GET_LENGTH(*q) == str_len && memcmp(Q_GET_DATA(*q), str, str_len) == 0) {
 return pool->total_prev_len + (q - pool->qstrs);
 }
 }
 }

 // not found; return null qstr
 return 0;
}

qstr qstr_from_str(const char *str) {
 return qstr_from_strn(str, strlen(str));
}

qstr qstr_from_strn(const char *str, size_t len) {
 QSTR_ENTER();
 qstr q = qstr_find_strn(str, len);
 if (q == 0) {
 // qstr does not exist in interned pool so need to add it

 // check that len is not too big
 if (len >= (1 << (8 * MICROPY_QSTR_BYTES_IN_LEN))) {
 QSTR_EXIT();
 mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("name too long"));
 }

 // compute number of bytes needed to intern this string
 size_t n_bytes = MICROPY_QSTR_BYTES_IN_HASH + MICROPY_QSTR_BYTES_IN_LEN + len + 1;

 if (MP_STATE_VM(qstr_last_chunk) != NULL && MP_STATE_VM(qstr_last_used) + n_bytes > MP_STATE_VM(qstr_last_alloc)) {
 // not enough room at end of previously interned string so try to grow
 byte *new_p = m_renew_maybe(byte, MP_STATE_VM(qstr_last_chunk), MP_STATE_VM(qstr_last_alloc), MP_STATE_VM(qstr_last_alloc) + n_bytes, false);
 if (new_p == NULL) {
 // could not grow existing memory; shrink it to fit previous
 (void)m_renew_maybe(byte, MP_STATE_VM(qstr_last_chunk), MP_STATE_VM(qstr_last_alloc), MP_STATE_VM(qstr_last_used), false);
 MP_STATE_VM(qstr_last_chunk) = NULL;
 } else {
 // could grow existing memory
 MP_STATE_VM(qstr_last_alloc) += n_bytes;
 }
 }

 if (MP_STATE_VM(qstr_last_chunk) == NULL) {
 // no existing memory for the interned string so allocate a new chunk
 size_t al = n_bytes;
 if (al < MICROPY_ALLOC_QSTR_CHUNK_INIT) {
 al = MICROPY_ALLOC_QSTR_CHUNK_INIT;
 }
 MP_STATE_VM(qstr_last_chunk) = m_new_maybe(byte, al);
 if (MP_STATE_VM(qstr_last_chunk) == NULL) {
 // failed to allocate a large chunk so try with exact size
 MP_STATE_VM(qstr_last_chunk) = m_new_maybe(byte, n_bytes);
 if (MP_STATE_VM(qstr_last_chunk) == NULL) {
 QSTR_EXIT();
 m_malloc_fail(n_bytes);
 }
 al = n_bytes;
 }
 MP_STATE_VM(qstr_last_alloc) = al;
 MP_STATE_VM(qstr_last_used) = 0;
 }

 // allocate memory from the chunk for this new interned string's data
 byte *q_ptr = MP_STATE_VM(qstr_last_chunk) + MP_STATE_VM(qstr_last_used);
 MP_STATE_VM(qstr_last_used) += n_bytes;

 // store the interned strings' data
 mp_uint_t hash = qstr_compute_hash((const byte *)str, len);
 Q_SET_HASH(q_ptr, hash);
 Q_SET_LENGTH(q_ptr, len);
 memcpy(q_ptr + MICROPY_QSTR_BYTES_IN_HASH + MICROPY_QSTR_BYTES_IN_LEN, str, len);
 q_ptr[MICROPY_QSTR_BYTES_IN_HASH + MICROPY_QSTR_BYTES_IN_LEN + len] = '0円';
 q = qstr_add(q_ptr);
 }
 QSTR_EXIT();
 return q;
}

mp_uint_t qstr_hash(qstr q) {
 const byte *qd = find_qstr(q);
 return Q_GET_HASH(qd);
}

size_t qstr_len(qstr q) {
 const byte *qd = find_qstr(q);
 return Q_GET_LENGTH(qd);
}

const char *qstr_str(qstr q) {
 const byte *qd = find_qstr(q);
 return (const char *)Q_GET_DATA(qd);
}

const byte *qstr_data(qstr q, size_t *len) {
 const byte *qd = find_qstr(q);
 *len = Q_GET_LENGTH(qd);
 return Q_GET_DATA(qd);
}

void qstr_pool_info(size_t *n_pool, size_t *n_qstr, size_t *n_str_data_bytes, size_t *n_total_bytes) {
 QSTR_ENTER();
 *n_pool = 0;
 *n_qstr = 0;
 *n_str_data_bytes = 0;
 *n_total_bytes = 0;
 for (qstr_pool_t *pool = MP_STATE_VM(last_pool); pool != NULL && pool != &CONST_POOL; pool = pool->prev) {
 *n_pool += 1;
 *n_qstr += pool->len;
 for (const byte **q = pool->qstrs, **q_top = pool->qstrs + pool->len; q < q_top; q++) {
 *n_str_data_bytes += Q_GET_ALLOC(*q);
 }
 #if MICROPY_ENABLE_GC
 *n_total_bytes += gc_nbytes(pool); // this counts actual bytes used in heap
 #else
 *n_total_bytes += sizeof(qstr_pool_t) + sizeof(qstr) * pool->alloc;
 #endif
 }
 *n_total_bytes += *n_str_data_bytes;
 QSTR_EXIT();
}

#if MICROPY_PY_MICROPYTHON_MEM_INFO
void qstr_dump_data(void) {
 QSTR_ENTER();
 for (qstr_pool_t *pool = MP_STATE_VM(last_pool); pool != NULL && pool != &CONST_POOL; pool = pool->prev) {
 for (const byte **q = pool->qstrs, **q_top = pool->qstrs + pool->len; q < q_top; q++) {
 mp_printf(&mp_plat_print, "Q(%s)\n", Q_GET_DATA(*q));
 }
 }
 QSTR_EXIT();
}
#endif

#if MICROPY_ROM_TEXT_COMPRESSION

#ifdef NO_QSTR

// If NO_QSTR is set, it means we're doing QSTR extraction.
// So we won't yet have "genhdr/compressed.data.h"

#else

// Emit the compressed_string_data string.
#define MP_COMPRESSED_DATA(x) STATIC const char *compressed_string_data = x;
#define MP_MATCH_COMPRESSED(a, b)
#include "genhdr/compressed.data.h"
#undef MP_COMPRESSED_DATA
#undef MP_MATCH_COMPRESSED

#endif // NO_QSTR

// This implements the "common word" compression scheme (see makecompresseddata.py) where the most
// common 128 words in error messages are replaced by their index into the list of common words.

// The compressed string data is delimited by setting high bit in the final char of each word.
// e.g. aaaa<0x80|a>bbbbbb<0x80|b>....
// This method finds the n'th string.
STATIC const byte *find_uncompressed_string(uint8_t n) {
 const byte *c = (byte *)compressed_string_data;
 while (n > 0) {
 while ((*c & 0x80) == 0) {
 ++c;
 }
 ++c;
 --n;
 }
 return c;
}

// Given a compressed string in src, decompresses it into dst.
// dst must be large enough (use MP_MAX_UNCOMPRESSED_TEXT_LEN+1).
void mp_decompress_rom_string(byte *dst, const mp_rom_error_text_t src_chr) {
 // Skip past the 0xff marker.
 const byte *src = (byte *)src_chr + 1;
 // Need to add spaces around compressed words, except for the first (i.e. transition from 1<->2).
 // 0 = start, 1 = compressed, 2 = regular.
 int state = 0;
 while (*src) {
 if ((byte) * src >= 128) {
 if (state != 0) {
 *dst++ = ' ';
 }
 state = 1;

 // High bit set, replace with common word.
 const byte *word = find_uncompressed_string(*src & 0x7f);
 // The word is terminated by the final char having its high bit set.
 while ((*word & 0x80) == 0) {
 *dst++ = *word++;
 }
 *dst++ = (*word & 0x7f);
 } else {
 // Otherwise just copy one char.
 if (state == 1) {
 *dst++ = ' ';
 }
 state = 2;

 *dst++ = *src;
 }
 ++src;
 }
 // Add null-terminator.
 *dst = 0;
}

#endif // MICROPY_ROM_TEXT_COMPRESSION