/*
  Copyright 2011-2020 David Robillard <d@drobilla.net>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include "reader.h"
#include "byte_source.h"
#include "stack.h"
#include "system.h"

#include "serd_internal.h"

#include <errno.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

SerdStatus
r_err(SerdReader* reader, SerdStatus st, const char* fmt, ...)
{
  va_list args;
  va_start(args, fmt);
  const Cursor* const cur = &reader->source.cur;
  const SerdError     e = {st, cur->filename, cur->line, cur->col, fmt, &args};
  serd_error(reader->error_sink, reader->error_handle, &e);
  va_end(args);
  return st;
}

void
set_blank_id(SerdReader* reader, Ref ref, size_t buf_size)
{
  SerdNode*   node   = deref(reader, ref);
  const char* prefix = reader->bprefix ? (const char*)reader->bprefix : "";
  node->n_bytes      = (size_t)snprintf(
    (char*)node->buf, buf_size, "%sb%u", prefix, reader->next_id++);
}

size_t
genid_size(SerdReader* reader)
{
  return reader->bprefix_len + 1 + 10 + 1; // + "b" + UINT32_MAX + \0
}

Ref
blank_id(SerdReader* reader)
{
  Ref ref = push_node_padded(reader, genid_size(reader), SERD_BLANK, "", 0);
  set_blank_id(reader, ref, genid_size(reader));
  return ref;
}

/** fread-like wrapper for getc (which is faster). */
static size_t
serd_file_read_byte(void* buf, size_t size, size_t nmemb, void* stream)
{
  (void)size;
  (void)nmemb;

  const int c = getc((FILE*)stream);
  if (c == EOF) {
    *((uint8_t*)buf) = 0;
    return 0;
  }
  *((uint8_t*)buf) = (uint8_t)c;
  return 1;
}

Ref
push_node_padded(SerdReader*  reader,
                 size_t       maxlen,
                 SerdNodeType type,
                 const char*  str,
                 size_t       n_bytes)
{
  void* mem = serd_stack_push_aligned(
    &reader->stack, sizeof(SerdNode) + maxlen + 1, sizeof(SerdNode));

  SerdNode* const node = (SerdNode*)mem;
  node->n_bytes        = n_bytes;
  node->flags          = 0;
  node->type           = type;
  node->buf            = NULL;

  char* buf = (char*)(node + 1);
  memcpy(buf, str, n_bytes + 1);

#ifdef SERD_STACK_CHECK
  reader->allocs                       = (Ref*)realloc(reader->allocs,
                                 sizeof(reader->allocs) * (++reader->n_allocs));
  reader->allocs[reader->n_allocs - 1] = ((char*)mem - reader->stack.buf);
#endif
  return (Ref)((char*)node - reader->stack.buf);
}

Ref
push_node(SerdReader*  reader,
          SerdNodeType type,
          const char*  str,
          size_t       n_bytes)
{
  return push_node_padded(reader, n_bytes, type, str, n_bytes);
}

SerdNode*
deref(SerdReader* reader, const Ref ref)
{
  if (ref) {
    SerdNode* node = (SerdNode*)(reader->stack.buf + ref);
    node->buf      = (char*)node + sizeof(SerdNode);
    return node;
  }
  return NULL;
}

Ref
pop_node(SerdReader* reader, Ref ref)
{
  if (ref && ref != reader->rdf_first && ref != reader->rdf_rest &&
      ref != reader->rdf_nil) {
#ifdef SERD_STACK_CHECK
    SERD_STACK_ASSERT_TOP(reader, ref);
    --reader->n_allocs;
#endif
    SerdNode* const node = deref(reader, ref);
    char* const     top  = reader->stack.buf + reader->stack.size;
    serd_stack_pop_aligned(&reader->stack, (size_t)(top - (char*)node));
  }
  return 0;
}

SerdStatus
emit_statement(SerdReader* reader, ReadContext ctx, Ref o, Ref d, Ref l)
{
  SerdNode* graph = deref(reader, ctx.graph);
  if (!graph && reader->default_graph.buf) {
    graph = &reader->default_graph;
  }

  const SerdStatus st = !reader->statement_sink
                          ? SERD_SUCCESS
                          : reader->statement_sink(reader->handle,
                                                   *ctx.flags,
                                                   graph,
                                                   deref(reader, ctx.subject),
                                                   deref(reader, ctx.predicate),
                                                   deref(reader, o),
                                                   deref(reader, d),
                                                   deref(reader, l));

  *ctx.flags &= SERD_ANON_CONT | SERD_LIST_CONT; // Preserve only cont flags
  return st;
}

static SerdStatus
read_statement(SerdReader* reader)
{
  return read_n3_statement(reader);
}

static SerdStatus
read_doc(SerdReader* reader)
{
  return ((reader->syntax == SERD_NQUADS) ? read_nquadsDoc(reader)
                                          : read_turtleTrigDoc(reader));
}

SerdReader*
serd_reader_new(SerdSyntax syntax,
                void*      handle,
                void (*free_handle)(void*),
                SerdBaseSink      base_sink,
                SerdPrefixSink    prefix_sink,
                SerdStatementSink statement_sink,
                SerdEndSink       end_sink)
{
  SerdReader* me     = (SerdReader*)calloc(1, sizeof(SerdReader));
  me->handle         = handle;
  me->free_handle    = free_handle;
  me->base_sink      = base_sink;
  me->prefix_sink    = prefix_sink;
  me->statement_sink = statement_sink;
  me->end_sink       = end_sink;
  me->default_graph  = SERD_NODE_NULL;
  me->stack          = serd_stack_new(SERD_PAGE_SIZE);
  me->syntax         = syntax;
  me->next_id        = 1;
  me->strict         = true;

  me->rdf_first = push_node(me, SERD_URI, NS_RDF "first", 48);
  me->rdf_rest  = push_node(me, SERD_URI, NS_RDF "rest", 47);
  me->rdf_nil   = push_node(me, SERD_URI, NS_RDF "nil", 46);

  return me;
}

void
serd_reader_set_strict(SerdReader* reader, bool strict)
{
  reader->strict = strict;
}

void
serd_reader_set_error_sink(SerdReader*   reader,
                           SerdErrorSink error_sink,
                           void*         error_handle)
{
  reader->error_sink   = error_sink;
  reader->error_handle = error_handle;
}

void
serd_reader_free(SerdReader* reader)
{
  if (!reader) {
    return;
  }

  pop_node(reader, reader->rdf_nil);
  pop_node(reader, reader->rdf_rest);
  pop_node(reader, reader->rdf_first);
  serd_node_free(&reader->default_graph);

#ifdef SERD_STACK_CHECK
  free(reader->allocs);
#endif
  free(reader->stack.buf);
  free(reader->bprefix);
  if (reader->free_handle) {
    reader->free_handle(reader->handle);
  }
  free(reader);
}

void*
serd_reader_get_handle(const SerdReader* reader)
{
  return reader->handle;
}

void
serd_reader_add_blank_prefix(SerdReader* reader, const char* prefix)
{
  free(reader->bprefix);
  reader->bprefix_len = 0;
  reader->bprefix     = NULL;

  const size_t prefix_len = prefix ? strlen(prefix) : 0;
  if (prefix_len) {
    reader->bprefix_len = prefix_len;
    reader->bprefix     = (char*)malloc(reader->bprefix_len + 1);
    memcpy(reader->bprefix, prefix, reader->bprefix_len + 1);
  }
}

void
serd_reader_set_default_graph(SerdReader* reader, const SerdNode* graph)
{
  serd_node_free(&reader->default_graph);
  reader->default_graph = serd_node_copy(graph);
}

SerdStatus
serd_reader_read_file(SerdReader* reader, const char* uri)
{
  char* const path = serd_file_uri_parse(uri, NULL);
  if (!path) {
    return SERD_ERR_BAD_ARG;
  }

  FILE* fd = serd_fopen(path, "rb");
  if (!fd) {
    serd_free(path);
    return SERD_ERR_UNKNOWN;
  }

  SerdStatus ret = serd_reader_read_file_handle(reader, fd, path);
  fclose(fd);
  free(path);
  return ret;
}

static SerdStatus
skip_bom(SerdReader* me)
{
  if (serd_byte_source_peek(&me->source) == 0xEF) {
    serd_byte_source_advance(&me->source);
    if (serd_byte_source_peek(&me->source) != 0xBB ||
        serd_byte_source_advance(&me->source) ||
        serd_byte_source_peek(&me->source) != 0xBF ||
        serd_byte_source_advance(&me->source)) {
      r_err(me, SERD_ERR_BAD_SYNTAX, "corrupt byte order mark\n");
      return SERD_ERR_BAD_SYNTAX;
    }
  }

  return SERD_SUCCESS;
}

SerdStatus
serd_reader_start_stream(SerdReader* reader,
                         FILE*       file,
                         const char* name,
                         bool        bulk)
{
  return serd_reader_start_source_stream(reader,
                                         bulk ? (SerdSource)fread
                                              : serd_file_read_byte,
                                         (SerdStreamErrorFunc)ferror,
                                         file,
                                         name,
                                         bulk ? SERD_PAGE_SIZE : 1);
}

SerdStatus
serd_reader_start_source_stream(SerdReader*         reader,
                                SerdSource          read_func,
                                SerdStreamErrorFunc error_func,
                                void*               stream,
                                const char*         name,
                                size_t              page_size)
{
  return serd_byte_source_open_source(
    &reader->source, read_func, error_func, stream, name, page_size);
}

static SerdStatus
serd_reader_prepare(SerdReader* reader)
{
  SerdStatus st = serd_byte_source_prepare(&reader->source);
  if (st == SERD_SUCCESS) {
    st = skip_bom(reader);
  } else if (st == SERD_FAILURE) {
    reader->source.eof = true;
  } else {
    r_err(reader, st, "read error: %s\n", strerror(errno));
  }
  return st;
}

SerdStatus
serd_reader_read_chunk(SerdReader* reader)
{
  SerdStatus st = SERD_SUCCESS;
  if (!reader->source.prepared) {
    st = serd_reader_prepare(reader);
  } else if (reader->source.eof) {
    st = serd_byte_source_advance(&reader->source);
  }

  if (peek_byte(reader) == 0) {
    // Skip leading null byte, for reading from a null-delimited socket
    eat_byte_safe(reader, 0);
  }

  return st ? st : read_statement(reader);
}

SerdStatus
serd_reader_end_stream(SerdReader* reader)
{
  return serd_byte_source_close(&reader->source);
}

SerdStatus
serd_reader_read_file_handle(SerdReader* reader, FILE* file, const char* name)
{
  return serd_reader_read_source(reader,
                                 (SerdSource)fread,
                                 (SerdStreamErrorFunc)ferror,
                                 file,
                                 name,
                                 SERD_PAGE_SIZE);
}

SerdStatus
serd_reader_read_source(SerdReader*         reader,
                        SerdSource          source,
                        SerdStreamErrorFunc error,
                        void*               stream,
                        const char*         name,
                        size_t              page_size)
{
  SerdStatus st = serd_reader_start_source_stream(
    reader, source, error, stream, name, page_size);

  if (st || (st = serd_reader_prepare(reader))) {
    serd_reader_end_stream(reader);
    return st;
  }

  if ((st = read_doc(reader))) {
    serd_reader_end_stream(reader);
    return st;
  }

  return serd_reader_end_stream(reader);
}

SerdStatus
serd_reader_read_string(SerdReader* reader, const char* utf8)
{
  serd_byte_source_open_string(&reader->source, utf8);

  SerdStatus st = serd_reader_prepare(reader);
  if (!st) {
    st = read_doc(reader);
  }

  serd_byte_source_close(&reader->source);

  return st;
}