/*
  Copyright 2011-2016 David Robillard <http://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.
*/

#ifndef SERD_INTERNAL_H
#define SERD_INTERNAL_H

#define _POSIX_C_SOURCE 200809L /* for posix_memalign and posix_fadvise */

#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "serd/serd.h"
#include "serd_config.h"

#if defined(HAVE_POSIX_FADVISE) && defined(HAVE_FILENO)
#   include <fcntl.h>
#endif

#define NS_XSD "http://www.w3.org/2001/XMLSchema#"
#define NS_RDF "http://www.w3.org/1999/02/22-rdf-syntax-ns#"

#define SERD_PAGE_SIZE 4096

#ifndef MIN
#    define MIN(a, b) (((a) < (b)) ? (a) : (b))
#endif

#if defined(__GNUC__)
#    define SERD_LOG_FUNC(fmt, arg1) __attribute__((format(printf, fmt, arg1)))
#else
#    define SERD_LOG_FUNC(fmt, arg1)
#endif

static const uint8_t replacement_char[] = { 0xEF, 0xBF, 0xBD };

/* File and Buffer Utilities */

static inline FILE*
serd_fopen(const char* path, const char* mode)
{
	FILE* fd = fopen(path, mode);
	if (!fd) {
		fprintf(stderr, "error: failed to open file %s (%s)\n",
		        path, strerror(errno));
		return NULL;
	}
#if defined(HAVE_POSIX_FADVISE) && defined(HAVE_FILENO)
	posix_fadvise(fileno(fd), 0, 0, POSIX_FADV_SEQUENTIAL);
#endif
	return fd;
}

static inline void*
serd_bufalloc(size_t size)
{
#ifdef HAVE_POSIX_MEMALIGN
	void* ptr;
	const int ret = posix_memalign(&ptr, SERD_PAGE_SIZE, size);
	return ret ? NULL : ptr;
#else
	return malloc(size);
#endif
}

/* Byte source */

typedef struct {
	const uint8_t* filename;
	unsigned       line;
	unsigned       col;
} Cursor;

typedef struct {
	SerdSource          read_func;    ///< Read function (e.g. fread)
	SerdStreamErrorFunc error_func;   ///< Error function (e.g. ferror)
	void*               stream;       ///< Stream (e.g. FILE)
	size_t              page_size;    ///< Number of bytes to read at a time
	Cursor              cur;          ///< Cursor for error reporting
	uint8_t*            file_buf;     ///< Buffer iff reading pages from a file
	const uint8_t*      read_buf;     ///< Pointer to file_buf or read_byte
	size_t              read_head;    ///< Offset into read_buf
	uint8_t             read_byte;    ///< 1-byte 'buffer' used when not paging
	bool                from_stream;  ///< True iff reading from `stream`
	bool                prepared;     ///< True iff prepared for reading
	bool                eof;          ///< True iff end of file reached
} SerdByteSource;

SerdStatus
serd_byte_source_open_file(SerdByteSource* source,
                           FILE*           file,
                           bool            bulk);

SerdStatus
serd_byte_source_open_string(SerdByteSource* source, const uint8_t* utf8);

SerdStatus
serd_byte_source_open_source(SerdByteSource*     source,
                             SerdSource          read_func,
                             SerdStreamErrorFunc error_func,
                             void*               stream,
                             const uint8_t*      name,
                             size_t              page_size);

SerdStatus
serd_byte_source_close(SerdByteSource* source);

SerdStatus
serd_byte_source_prepare(SerdByteSource* source);

SerdStatus
serd_byte_source_page(SerdByteSource* source);

static inline uint8_t
serd_byte_source_peek(SerdByteSource* source)
{
	assert(source->prepared);
	return source->read_buf[source->read_head];
}

static inline SerdStatus
serd_byte_source_advance(SerdByteSource* source)
{
	SerdStatus st = SERD_SUCCESS;

	switch (serd_byte_source_peek(source)) {
	case '\0': break;
	case '\n': ++source->cur.line; source->cur.col = 0; break;
	default:   ++source->cur.col;
	}

	if (source->from_stream) {
		source->eof = false;
		if (source->page_size > 1) {
			if (++source->read_head == source->page_size) {
				st = serd_byte_source_page(source);
			}
		} else {
			if (!source->read_func(&source->read_byte, 1, 1, source->stream)) {
				st = source->error_func(source->stream) ? SERD_ERR_UNKNOWN
				                                        : SERD_FAILURE;
			}
		}
	} else if (!source->eof) {
		++source->read_head; // Move to next character in string
	}

	return source->eof ? SERD_FAILURE : st;
}

/* Stack */

/** A dynamic stack in memory. */
typedef struct {
	uint8_t* buf;       ///< Stack memory
	size_t   buf_size;  ///< Allocated size of buf (>= size)
	size_t   size;      ///< Conceptual size of stack in buf
} SerdStack;

/** An offset to start the stack at. Note 0 is reserved for NULL. */
#define SERD_STACK_BOTTOM sizeof(void*)

static inline SerdStack
serd_stack_new(size_t size)
{
	SerdStack stack;
	stack.buf       = (uint8_t*)calloc(size, 1);
	stack.buf_size  = size;
	stack.size      = SERD_STACK_BOTTOM;
	return stack;
}

static inline bool
serd_stack_is_empty(SerdStack* stack)
{
	return stack->size <= SERD_STACK_BOTTOM;
}

static inline void
serd_stack_free(SerdStack* stack)
{
	free(stack->buf);
	stack->buf      = NULL;
	stack->buf_size = 0;
	stack->size     = 0;
}

static inline uint8_t*
serd_stack_push(SerdStack* stack, size_t n_bytes)
{
	const size_t new_size = stack->size + n_bytes;
	if (stack->buf_size < new_size) {
		stack->buf_size += (stack->buf_size >> 1); // *= 1.5
		stack->buf = (uint8_t*)realloc(stack->buf, stack->buf_size);
	}
	uint8_t* const ret = (stack->buf + stack->size);
	stack->size = new_size;
	return ret;
}

static inline void
serd_stack_pop(SerdStack* stack, size_t n_bytes)
{
	assert(stack->size >= n_bytes);
	stack->size -= n_bytes;
}

static inline void*
serd_stack_push_aligned(SerdStack* stack, size_t n_bytes, size_t align)
{
	// Push one byte to ensure space for a pad count
	serd_stack_push(stack, 1);

	// Push padding if necessary
	const size_t pad = align - stack->size % align;
	if (pad > 0) {
		serd_stack_push(stack, pad);
	}

	// Set top of stack to pad count so we can properly pop later
	assert(pad < UINT8_MAX);
	stack->buf[stack->size - 1] = (uint8_t)pad;

	// Push requested space at aligned location
	return serd_stack_push(stack, n_bytes);
}

static inline void
serd_stack_pop_aligned(SerdStack* stack, size_t n_bytes)
{
	// Pop requested space down to aligned location
	serd_stack_pop(stack, n_bytes);

	// Get amount of padding from top of stack
	const uint8_t pad = stack->buf[stack->size - 1];

	// Pop padding and pad count
	serd_stack_pop(stack, pad + 1u);
}

/* Byte Sink */

typedef struct SerdByteSinkImpl {
	SerdSink sink;
	void*    stream;
	uint8_t* buf;
	size_t   size;
	size_t   block_size;
} SerdByteSink;

static inline SerdByteSink
serd_byte_sink_new(SerdSink sink, void* stream, size_t block_size)
{
	SerdByteSink bsink;
	bsink.sink       = sink;
	bsink.stream     = stream;
	bsink.size       = 0;
	bsink.block_size = block_size;
	bsink.buf        = ((block_size > 1)
	                    ? (uint8_t*)serd_bufalloc(block_size)
	                    : NULL);
	return bsink;
}

static inline void
serd_byte_sink_flush(SerdByteSink* bsink)
{
	if (bsink->block_size > 1 && bsink->size > 0) {
		bsink->sink(bsink->buf, bsink->size, bsink->stream);
		bsink->size = 0;
	}
}

static inline void
serd_byte_sink_free(SerdByteSink* bsink)
{
	serd_byte_sink_flush(bsink);
	free(bsink->buf);
	bsink->buf = NULL;
}

static inline size_t
serd_byte_sink_write(const void* buf, size_t len, SerdByteSink* bsink)
{
	if (len == 0) {
		return 0;
	} else if (bsink->block_size == 1) {
		return bsink->sink(buf, len, bsink->stream);
	}

	const size_t orig_len = len;
	while (len) {
		const size_t space = bsink->block_size - bsink->size;
		const size_t n     = MIN(space, len);

		// Write as much as possible into the remaining buffer space
		memcpy(bsink->buf + bsink->size, buf, n);
		bsink->size += n;
		buf          = (const uint8_t*)buf + n;
		len         -= n;

		// Flush page if buffer is full
		if (bsink->size == bsink->block_size) {
			bsink->sink(bsink->buf, bsink->block_size, bsink->stream);
			bsink->size = 0;
		}
	}
	return orig_len;
}

/* Character utilities */

/** Return true if `c` lies within [`min`...`max`] (inclusive) */
static inline bool
in_range(const uint8_t c, const uint8_t min, const uint8_t max)
{
	return (c >= min && c <= max);
}

/** RFC2234: ALPHA ::= %x41-5A / %x61-7A  ; A-Z / a-z */
static inline bool
is_alpha(const uint8_t c)
{
	return in_range(c, 'A', 'Z') || in_range(c, 'a', 'z');
}

/** RFC2234: DIGIT ::= %x30-39  ; 0-9 */
static inline bool
is_digit(const uint8_t c)
{
	return in_range(c, '0', '9');
}

/* RFC2234: HEXDIG ::= DIGIT / "A" / "B" / "C" / "D" / "E" / "F" */
static inline bool
is_hexdig(const uint8_t c)
{
	return is_digit(c) || in_range(c, 'A', 'F');
}

/* Turtle / JSON / C: XDIGIT ::= DIGIT / A-F / a-f */
static inline bool
is_xdigit(const uint8_t c)
{
	return is_hexdig(c) || in_range(c, 'a', 'f');
}

static inline bool
is_space(const char c)
{
	switch (c) {
	case ' ': case '\f': case '\n': case '\r': case '\t': case '\v':
		return true;
	default:
		return false;
	}
}

static inline bool
is_base64(const uint8_t c)
{
	return is_alpha(c) || is_digit(c) || c == '+' || c == '/' || c == '=';
}

static inline bool
is_windows_path(const uint8_t* path)
{
	return is_alpha(path[0]) && (path[1] == ':' || path[1] == '|')
		&& (path[2] == '/' || path[2] == '\\');
}

/* String utilities */

size_t
serd_substrlen(const uint8_t* str,
               size_t         len,
               size_t*        n_bytes,
               SerdNodeFlags* flags);

static inline int
serd_strncasecmp(const char* s1, const char* s2, size_t n)
{
	for (; n > 0 && *s2; s1++, s2++, --n) {
		if (toupper(*s1) != toupper(*s2)) {
			return ((*(const uint8_t*)s1 < *(const uint8_t*)s2) ? -1 : +1);
		}
	}
	return 0;
}

static inline uint32_t
utf8_num_bytes(const uint8_t c)
{
	if ((c & 0x80) == 0) {  // Starts with `0'
		return 1;
	} else if ((c & 0xE0) == 0xC0) {  // Starts with `110'
		return 2;
	} else if ((c & 0xF0) == 0xE0) {  // Starts with `1110'
		return 3;
	} else if ((c & 0xF8) == 0xF0) {  // Starts with `11110'
		return 4;
	}
	return 0;
}

/// Return the code point of a UTF-8 character with known length
static inline uint32_t
parse_counted_utf8_char(const uint8_t* utf8, size_t size)
{
	uint32_t c = utf8[0] & ((1u << (8 - size)) - 1);
	for (size_t i = 1; i < size; ++i) {
		const uint8_t in = utf8[i] & 0x3F;
		c = (c << 6) | in;
	}
	return c;
}

/// Parse a UTF-8 character, set *size to the length, and return the code point
static inline uint32_t
parse_utf8_char(const uint8_t* utf8, size_t* size)
{
	switch (*size = utf8_num_bytes(utf8[0])) {
	case 1: case 2: case 3: case 4:
		return parse_counted_utf8_char(utf8, *size);
	default:
		*size = 0;
		return 0;
	}
}

/* URI utilities */

static inline bool
chunk_equals(const SerdChunk* a, const SerdChunk* b)
{
	return a->len == b->len
		&& !strncmp((const char*)a->buf, (const char*)b->buf, a->len);
}

static inline size_t
uri_path_len(const SerdURI* uri)
{
	return uri->path_base.len + uri->path.len;
}

static inline uint8_t
uri_path_at(const SerdURI* uri, size_t i)
{
	if (i < uri->path_base.len) {
		return uri->path_base.buf[i];
	} else {
		return uri->path.buf[i - uri->path_base.len];
	}
}

/**
   Return the index of the first differing character after the last root slash,
   or zero if `uri` is not under `root`.
*/
static inline size_t
uri_rooted_index(const SerdURI* uri, const SerdURI* root)
{
	if (!root || !root->scheme.len ||
	    !chunk_equals(&root->scheme, &uri->scheme) ||
	    !chunk_equals(&root->authority, &uri->authority)) {
		return 0;
	}

	bool         differ          = false;
	const size_t path_len        = uri_path_len(uri);
	const size_t root_len        = uri_path_len(root);
	size_t       last_root_slash = 0;
	for (size_t i = 0; i < path_len && i < root_len; ++i) {
		const uint8_t u = uri_path_at(uri, i);
		const uint8_t r = uri_path_at(root, i);

		differ = differ || u != r;
		if (r == '/') {
			last_root_slash = i;
			if (differ) {
				return 0;
			}
		}
	}

	return last_root_slash + 1;
}

/** Return true iff `uri` shares path components with `root` */
static inline bool
uri_is_related(const SerdURI* uri, const SerdURI* root)
{
	return uri_rooted_index(uri, root) > 0;
}

/** Return true iff `uri` is within the base of `root` */
static inline bool
uri_is_under(const SerdURI* uri, const SerdURI* root)
{
	const size_t index = uri_rooted_index(uri, root);
	return index > 0 && uri->path.len > index;
}

static inline bool
is_uri_scheme_char(const uint8_t c)
{
	switch (c) {
	case ':': case '+': case '-': case '.':
		return true;
	default:
		return is_alpha(c) || is_digit(c);
	}
}

/* Error reporting */

static inline void
serd_error(SerdErrorSink error_sink, void* handle, const SerdError* e)
{
	if (error_sink) {
		error_sink(handle, e);
	} else {
		fprintf(stderr, "error: %s:%u:%u: ", e->filename, e->line, e->col);
		vfprintf(stderr, e->fmt, *e->args);
	}
}

SERD_LOG_FUNC(3, 4)
int
r_err(SerdReader* reader, SerdStatus st, const char* fmt, ...);

/* Reader */

#ifdef SERD_STACK_CHECK
#    define SERD_STACK_ASSERT_TOP(reader, ref) \
            assert(ref == reader->allocs[reader->n_allocs - 1]);
#else
#    define SERD_STACK_ASSERT_TOP(reader, ref)
#endif

/* Reference to a node in the stack (we can not use pointers since the
   stack may be reallocated, invalidating any pointers to elements).
*/
typedef size_t Ref;

typedef struct {
	Ref                 graph;
	Ref                 subject;
	Ref                 predicate;
	Ref                 object;
	Ref                 datatype;
	Ref                 lang;
	SerdStatementFlags* flags;
} ReadContext;

struct SerdReaderImpl {
	void*             handle;
	void              (*free_handle)(void* ptr);
	SerdBaseSink      base_sink;
	SerdPrefixSink    prefix_sink;
	SerdStatementSink statement_sink;
	SerdEndSink       end_sink;
	SerdErrorSink     error_sink;
	void*             error_handle;
	Ref               rdf_first;
	Ref               rdf_rest;
	Ref               rdf_nil;
	SerdNode          default_graph;
	SerdByteSource    source;
	SerdStack         stack;
	SerdSyntax        syntax;
	unsigned          next_id;
	SerdStatus        status;
	uint8_t*          buf;
	uint8_t*          bprefix;
	size_t            bprefix_len;
	bool              strict;     ///< True iff strict parsing
	bool              seen_genid;
#ifdef SERD_STACK_CHECK
	Ref*              allocs;     ///< Stack of push offsets
	size_t            n_allocs;   ///< Number of stack pushes
#endif
};

Ref push_node_padded(SerdReader* reader,
                     size_t      maxlen,
                     SerdType    type,
                     const char* str,
                     size_t      n_bytes);

Ref push_node(SerdReader* reader,
              SerdType    type,
              const char* str,
              size_t      n_bytes);

size_t genid_size(SerdReader* reader);
Ref    blank_id(SerdReader* reader);
void   set_blank_id(SerdReader* reader, Ref ref, size_t buf_size);

SerdNode* deref(SerdReader* reader, Ref ref);

Ref pop_node(SerdReader* reader, Ref ref);

bool emit_statement(SerdReader* reader, ReadContext ctx, Ref o, Ref d, Ref l);

bool read_n3_statement(SerdReader* reader);
bool read_nquadsDoc(SerdReader* reader);
bool read_turtleTrigDoc(SerdReader* reader);

typedef enum {
	FIELD_NONE,
	FIELD_SUBJECT,
	FIELD_PREDICATE,
	FIELD_OBJECT,
	FIELD_GRAPH
} Field;

#endif  // SERD_INTERNAL_H