/*
   * 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"
  
  // 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 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
  
  // 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
      10,                 // set so that the first dynamically allocated pool is twice this size; must be <= the len (just below)
      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
      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) {
          qstr_pool_t *pool = m_new_obj_var_maybe(qstr_pool_t, const char*, MP_STATE_VM(last_pool)->alloc * 2);
          if (pool == NULL) {
              QSTR_EXIT();
              m_malloc_fail(MP_STATE_VM(last_pool)->alloc * 2);
          }
          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 = MP_STATE_VM(last_pool)->alloc * 2;
          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) {
      assert(len < (1 << (8 * MICROPY_QSTR_BYTES_IN_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
  
          // 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';
          q = qstr_add(q_ptr);
      }
      QSTR_EXIT();
      return q;
  }
  
  mp_uint_t qstr_hash(qstr q) {
      return Q_GET_HASH(find_qstr(q));
  }
  
  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