#include <stdlib.h>
#include <assert.h>
#include <stdio.h>

#include "cmark_ctype.h"
#include "config.h"
#include "parser.h"
#include "cmark.h"
#include "node.h"
#include "references.h"
#include "utf8.h"
#include "scanners.h"
#include "inlines.h"
#include "houdini.h"
#include "buffer.h"
#include "debug.h"

#define CODE_INDENT 4
#define peek_at(i, n) (i)->data[n]

static void
S_parser_feed(cmark_parser *parser, const unsigned char *buffer, size_t len,
              bool eof);

static void
S_process_line(cmark_parser *parser, const unsigned char *buffer,
               size_t bytes);

static cmark_node* make_block(cmark_node_type tag, int start_line, int start_column)
{
	cmark_node* e;

	e = (cmark_node *)calloc(1, sizeof(*e));
	if(e != NULL) {
		e->type = tag;
		e->open = true;
		e->start_line = start_line;
		e->start_column = start_column;
		e->end_line = start_line;
		cmark_strbuf_init(&e->string_content, 32);
	}

	return e;
}

// Create a root document node.
static cmark_node* make_document()
{
	cmark_node *e = make_block(NODE_DOCUMENT, 1, 1);
	return e;
}

cmark_parser *cmark_parser_new(int options)
{
	cmark_parser *parser = (cmark_parser*)malloc(sizeof(cmark_parser));
	cmark_node *document = make_document();
	cmark_strbuf *line = (cmark_strbuf*)malloc(sizeof(cmark_strbuf));
	cmark_strbuf *buf  = (cmark_strbuf*)malloc(sizeof(cmark_strbuf));
	cmark_strbuf_init(line, 256);
	cmark_strbuf_init(buf, 0);

	parser->refmap = cmark_reference_map_new();
	parser->root = document;
	parser->current = document;
	parser->line_number = 0;
	parser->curline = line;
	parser->last_line_length = 0;
	parser->linebuf = buf;
	parser->options = options;

	return parser;
}

void cmark_parser_free(cmark_parser *parser)
{
	cmark_strbuf_free(parser->curline);
	free(parser->curline);
	cmark_strbuf_free(parser->linebuf);
	free(parser->linebuf);
	cmark_reference_map_free(parser->refmap);
	free(parser);
}

static cmark_node*
finalize(cmark_parser *parser, cmark_node* b);

// Returns true if line has only space characters, else false.
static bool is_blank(cmark_strbuf *s, int offset)
{
	while (offset < s->size) {
		switch (s->ptr[offset]) {
		case '\n':
			return true;
		case ' ':
			offset++;
			break;
		default:
			return false;
		}
	}

	return true;
}

static inline bool can_contain(cmark_node_type parent_type, cmark_node_type child_type)
{
	return ( parent_type == NODE_DOCUMENT ||
	         parent_type == NODE_BLOCK_QUOTE ||
	         parent_type == NODE_ITEM ||
	         (parent_type == NODE_LIST && child_type == NODE_ITEM) );
}

static inline bool accepts_lines(cmark_node_type block_type)
{
	return (block_type == NODE_PARAGRAPH ||
	        block_type == NODE_HEADER ||
	        block_type == NODE_CODE_BLOCK);
}

static void add_line(cmark_node* node, cmark_chunk *ch, int offset)
{
	assert(node->open);
	cmark_strbuf_put(&node->string_content, ch->data + offset, ch->len - offset);
}

static void remove_trailing_blank_lines(cmark_strbuf *ln)
{
	int i;

	for (i = ln->size - 1; i >= 0; --i) {
		unsigned char c = ln->ptr[i];

		if (c != ' ' && c != '\t' && c != '\r' && c != '\n')
			break;
	}

	if (i < 0) {
		cmark_strbuf_clear(ln);
		return;
	}

	i = cmark_strbuf_strchr(ln, '\n', i);
	if (i >= 0)
		cmark_strbuf_truncate(ln, i);
}

// Check to see if a node ends with a blank line, descending
// if needed into lists and sublists.
static bool ends_with_blank_line(cmark_node* node)
{
	cmark_node *cur = node;
	while (cur != NULL) {
		if (cur->last_line_blank) {
			return true;
		}
		if (cur->type == NODE_LIST || cur->type == NODE_ITEM) {
			cur = cur->last_child;
		} else {
			cur = NULL;
		}
	}
	return false;
}

// Break out of all containing lists
static int break_out_of_lists(cmark_parser *parser, cmark_node ** bptr)
{
	cmark_node *container = *bptr;
	cmark_node *b = parser->root;
	// find first containing NODE_LIST:
	while (b && b->type != NODE_LIST) {
		b = b->last_child;
	}
	if (b) {
		while (container && container != b) {
			container = finalize(parser, container);
		}
		finalize(parser, b);
		*bptr = b->parent;
	}
	return 0;
}


static cmark_node*
finalize(cmark_parser *parser, cmark_node* b)
{
	int firstlinelen;
	int pos;
	cmark_node* item;
	cmark_node* subitem;
	cmark_node* parent;

	parent = b->parent;

	assert(b->open);  // shouldn't call finalize on closed blocks
	b->open = false;

	if (parser->curline->size == 0) {
		// end of input - line number has not been incremented
		b->end_line = parser->line_number;
		b->end_column = parser->last_line_length;
	} else if (b->type == NODE_DOCUMENT ||
	           (b->type == NODE_CODE_BLOCK && b->as.code.fenced) ||
	           (b->type == NODE_HEADER && b->as.header.setext)) {
		b->end_line = parser->line_number;
		b->end_column = parser->curline->size -
		                (parser->curline->ptr[parser->curline->size - 1] == '\n' ?
		                 1 : 0);
	} else {
		b->end_line = parser->line_number - 1;
		b->end_column = parser->last_line_length;
	}

	switch (b->type) {
	case NODE_PARAGRAPH:
		while (cmark_strbuf_at(&b->string_content, 0) == '[' &&
		       (pos = cmark_parse_reference_inline(&b->string_content, parser->refmap))) {

			cmark_strbuf_drop(&b->string_content, pos);
		}
		if (is_blank(&b->string_content, 0)) {
			// remove blank node (former reference def)
			cmark_node_free(b);
		}
		break;

	case NODE_CODE_BLOCK:
		if (!b->as.code.fenced) { // indented code
			remove_trailing_blank_lines(&b->string_content);
			cmark_strbuf_putc(&b->string_content, '\n');
		} else {

			// first line of contents becomes info
			firstlinelen = cmark_strbuf_strchr(&b->string_content, '\n', 0);

			cmark_strbuf tmp = GH_BUF_INIT;
			houdini_unescape_html_f(
			    &tmp,
			    b->string_content.ptr,
			    firstlinelen
			);
			cmark_strbuf_trim(&tmp);
			cmark_strbuf_unescape(&tmp);
			b->as.code.info = cmark_chunk_buf_detach(&tmp);

			cmark_strbuf_drop(&b->string_content, firstlinelen + 1);
		}
		b->as.code.literal = cmark_chunk_buf_detach(&b->string_content);
		break;

	case NODE_HTML:
		b->as.literal = cmark_chunk_buf_detach(&b->string_content);
		break;

	case NODE_LIST: // determine tight/loose status
		b->as.list.tight = true; // tight by default
		item = b->first_child;

		while (item) {
			// check for non-final non-empty list item ending with blank line:
			if (item->last_line_blank && item->next) {
				b->as.list.tight = false;
				break;
			}
			// recurse into children of list item, to see if there are
			// spaces between them:
			subitem = item->first_child;
			while (subitem) {
				if (ends_with_blank_line(subitem) &&
				    (item->next || subitem->next)) {
					b->as.list.tight = false;
					break;
				}
				subitem = subitem->next;
			}
			if (!(b->as.list.tight)) {
				break;
			}
			item = item->next;
		}

		break;

	default:
		break;
	}
	return parent;
}

// Add a node as child of another.  Return pointer to child.
static cmark_node* add_child(cmark_parser *parser, cmark_node* parent,
                             cmark_node_type block_type, int start_column)
{
	assert(parent);

	// if 'parent' isn't the kind of node that can accept this child,
	// then back up til we hit a node that can.
	while (!can_contain(parent->type, block_type)) {
		parent = finalize(parser, parent);
	}

	cmark_node* child = make_block(block_type, parser->line_number, start_column);
	child->parent = parent;

	if (parent->last_child) {
		parent->last_child->next = child;
		child->prev = parent->last_child;
	} else {
		parent->first_child = child;
		child->prev = NULL;
	}
	parent->last_child = child;
	return child;
}


// Walk through node and all children, recursively, parsing
// string content into inline content where appropriate.
static void process_inlines(cmark_node* root, cmark_reference_map *refmap, int options)
{
	cmark_iter *iter = cmark_iter_new(root);
	cmark_node *cur;
	cmark_event_type ev_type;

	while ((ev_type = cmark_iter_next(iter)) != CMARK_EVENT_DONE) {
		cur = cmark_iter_get_node(iter);
		if (ev_type == CMARK_EVENT_ENTER) {
			if (cur->type == NODE_PARAGRAPH ||
			    cur->type == NODE_HEADER) {
				cmark_parse_inlines(cur, refmap, options);
			}
		}
	}

	cmark_iter_free(iter);
}

// Attempts to parse a list item marker (bullet or enumerated).
// On success, returns length of the marker, and populates
// data with the details.  On failure, returns 0.
static int parse_list_marker(cmark_chunk *input, int pos, cmark_list **dataptr)
{
	unsigned char c;
	int startpos;
	cmark_list *data;

	startpos = pos;
	c = peek_at(input, pos);

	if (c == '*' || c == '-' || c == '+') {
		pos++;
		if (!cmark_isspace(peek_at(input, pos))) {
			return 0;
		}
		data = (cmark_list *)calloc(1, sizeof(*data));
		if(data == NULL) {
			return 0;
		} else {
			data->marker_offset = 0; // will be adjusted later
			data->list_type = CMARK_BULLET_LIST;
			data->bullet_char = c;
			data->start = 1;
			data->delimiter = CMARK_PERIOD_DELIM;
			data->tight = false;
		}
	} else if (cmark_isdigit(c)) {
		int start = 0;

		do {
			start = (10 * start) + (peek_at(input, pos) - '0');
			pos++;
		} while (cmark_isdigit(peek_at(input, pos)));

		c = peek_at(input, pos);
		if (c == '.' || c == ')') {
			pos++;
			if (!cmark_isspace(peek_at(input, pos))) {
				return 0;
			}
			data = (cmark_list *)calloc(1, sizeof(*data));
			if(data == NULL) {
				return 0;
			} else {
				data->marker_offset = 0; // will be adjusted later
				data->list_type = CMARK_ORDERED_LIST;
				data->bullet_char = 0;
				data->start = start;
				data->delimiter = (c == '.' ? CMARK_PERIOD_DELIM : CMARK_PAREN_DELIM);
				data->tight = false;
			}
		} else {
			return 0;
		}

	} else {
		return 0;
	}

	*dataptr = data;
	return (pos - startpos);
}

// Return 1 if list item belongs in list, else 0.
static int lists_match(cmark_list *list_data, cmark_list *item_data)
{
	return (list_data->list_type == item_data->list_type &&
	        list_data->delimiter == item_data->delimiter &&
	        // list_data->marker_offset == item_data.marker_offset &&
	        list_data->bullet_char == item_data->bullet_char);
}

static cmark_node *finalize_document(cmark_parser *parser)
{
	while (parser->current != parser->root) {
		parser->current = finalize(parser, parser->current);
	}

	finalize(parser, parser->root);
	process_inlines(parser->root, parser->refmap, parser->options);

	return parser->root;
}

cmark_node *cmark_parse_file(FILE *f, int options)
{
	unsigned char buffer[4096];
	cmark_parser *parser = cmark_parser_new(options);
	size_t bytes;
	cmark_node *document;

	while ((bytes = fread(buffer, 1, sizeof(buffer), f)) > 0) {
		bool eof = bytes < sizeof(buffer);
		S_parser_feed(parser, buffer, bytes, eof);
		if (eof) {
			break;
		}
	}

	document = cmark_parser_finish(parser);
	cmark_parser_free(parser);
	return document;
}

cmark_node *cmark_parse_document(const char *buffer, size_t len, int options)
{
	cmark_parser *parser = cmark_parser_new(options);
	cmark_node *document;

	S_parser_feed(parser, (const unsigned char *)buffer, len, true);

	document = cmark_parser_finish(parser);
	cmark_parser_free(parser);
	return document;
}

void
cmark_parser_feed(cmark_parser *parser, const char *buffer, size_t len)
{
	S_parser_feed(parser, (const unsigned char *)buffer, len, false);
}

static void
S_parser_feed(cmark_parser *parser, const unsigned char *buffer, size_t len,
              bool eof)
{
	const unsigned char *end = buffer + len;

	while (buffer < end) {
		const unsigned char *eol
		    = (const unsigned char *)memchr(buffer, '\n',
		                                    end - buffer);
		size_t line_len;

		if (eol) {
			line_len = eol + 1 - buffer;
		} else if (eof) {
			line_len = end - buffer;
		} else {
			cmark_strbuf_put(parser->linebuf, buffer, end - buffer);
			break;
		}

		if (parser->linebuf->size > 0) {
			cmark_strbuf_put(parser->linebuf, buffer, line_len);
			S_process_line(parser, parser->linebuf->ptr,
			               parser->linebuf->size);
			cmark_strbuf_clear(parser->linebuf);
		} else {
			S_process_line(parser, buffer, line_len);
		}

		buffer += line_len;
	}
}

static void chop_trailing_hashtags(cmark_chunk *ch)
{
	int n, orig_n;

	cmark_chunk_rtrim(ch);
	orig_n = n = ch->len - 1;

	// if string ends in space followed by #s, remove these:
	while (n >= 0 && peek_at(ch, n) == '#')
		n--;

	// Check for a be a space before the final #s:
	if (n != orig_n && n >= 0 && peek_at(ch, n) == ' ') {
		ch->len = n;
		cmark_chunk_rtrim(ch);
	}
}

static void
S_process_line(cmark_parser *parser, const unsigned char *buffer, size_t bytes)
{
	cmark_node* last_matched_container;
	int offset = 0;
	int matched = 0;
	int lev = 0;
	int i;
	cmark_list *data = NULL;
	bool all_matched = true;
	cmark_node* container;
	bool blank = false;
	int first_nonspace;
	int indent;
	cmark_chunk input;
	bool maybe_lazy;

	utf8proc_detab(parser->curline, buffer, bytes);

	// Add a newline to the end if not present:
	// TODO this breaks abstraction:
	if (parser->curline->ptr[parser->curline->size - 1] != '\n') {
		cmark_strbuf_putc(parser->curline, '\n');
	}
	input.data = parser->curline->ptr;
	input.len = parser->curline->size;

	// container starts at the document root.
	container = parser->root;

	parser->line_number++;

	// for each containing node, try to parse the associated line start.
	// bail out on failure:  container will point to the last matching node.

	while (container->last_child && container->last_child->open) {
		container = container->last_child;

		first_nonspace = offset;
		while (peek_at(&input, first_nonspace) == ' ') {
			first_nonspace++;
		}

		indent = first_nonspace - offset;
		blank = peek_at(&input, first_nonspace) == '\n';

		if (container->type == NODE_BLOCK_QUOTE) {
			matched = indent <= 3 && peek_at(&input, first_nonspace) == '>';
			if (matched) {
				offset = first_nonspace + 1;
				if (peek_at(&input, offset) == ' ')
					offset++;
			} else {
				all_matched = false;
			}

		} else if (container->type == NODE_ITEM) {

			if (indent >= container->as.list.marker_offset +
			    container->as.list.padding) {
				offset += container->as.list.marker_offset +
				          container->as.list.padding;
			} else if (blank) {
				offset = first_nonspace;
			} else {
				all_matched = false;
			}

		} else if (container->type == NODE_CODE_BLOCK) {

			if (!container->as.code.fenced) { // indented
				if (indent >= CODE_INDENT) {
					offset += CODE_INDENT;
				} else if (blank) {
					offset = first_nonspace;
				} else {
					all_matched = false;
				}
			} else { // fenced
				matched = 0;
				if (indent <= 3 &&
				    (peek_at(&input, first_nonspace) ==
				     container->as.code.fence_char)) {
					matched = scan_close_code_fence(&input,
					                                first_nonspace);
				}
				if (matched >= container->as.code.fence_length) {
					// closing fence - and since we're at
					// the end of a line, we can return:
					all_matched = false;
					offset += matched;
					parser->current = finalize(parser, container);
					goto finished;
				} else {
					// skip opt. spaces of fence offset
					i = container->as.code.fence_offset;
					while (i > 0 &&
					       peek_at(&input, offset) == ' ') {
						offset++;
						i--;
					}
				}
			}
		} else if (container->type == NODE_HEADER) {

			// a header can never contain more than one line
			all_matched = false;

		} else if (container->type == NODE_HTML) {

			if (blank) {
				all_matched = false;
			}

		} else if (container->type == NODE_PARAGRAPH) {

			if (blank) {
				all_matched = false;
			}

		}

		if (!all_matched) {
			container = container->parent;  // back up to last matching node
			break;
		}
	}

	last_matched_container = container;

	// check to see if we've hit 2nd blank line, break out of list:
	if (blank && container->last_line_blank) {
		break_out_of_lists(parser, &container);
	}

	maybe_lazy = parser->current->type == NODE_PARAGRAPH;
	// try new container starts:
	while (container->type != NODE_CODE_BLOCK &&
	       container->type != NODE_HTML) {

		first_nonspace = offset;
		while (peek_at(&input, first_nonspace) == ' ')
			first_nonspace++;

		indent = first_nonspace - offset;
		blank = peek_at(&input, first_nonspace) == '\n';

		if (indent >= CODE_INDENT) {
			if (!maybe_lazy && !blank) {
				offset += CODE_INDENT;
				container = add_child(parser, container, NODE_CODE_BLOCK, offset + 1);
				container->as.code.fenced = false;
				container->as.code.fence_char = 0;
				container->as.code.fence_length = 0;
				container->as.code.fence_offset = 0;
				container->as.code.info = cmark_chunk_literal("");
			} else { // indent > 4 in lazy line
				break;
			}

		} else if (peek_at(&input, first_nonspace) == '>') {

			offset = first_nonspace + 1;
			// optional following character
			if (peek_at(&input, offset) == ' ')
				offset++;
			container = add_child(parser, container, NODE_BLOCK_QUOTE, offset + 1);

		} else if ((matched = scan_atx_header_start(&input, first_nonspace))) {

			offset = first_nonspace + matched;
			container = add_child(parser, container, NODE_HEADER, offset + 1);

			int hashpos = cmark_chunk_strchr(&input, '#', first_nonspace);
			int level = 0;

			while (peek_at(&input, hashpos) == '#') {
				level++;
				hashpos++;
			}
			container->as.header.level = level;
			container->as.header.setext = false;

		} else if ((matched = scan_open_code_fence(&input, first_nonspace))) {

			container = add_child(parser, container, NODE_CODE_BLOCK, first_nonspace + 1);
			container->as.code.fenced = true;
			container->as.code.fence_char = peek_at(&input, first_nonspace);
			container->as.code.fence_length = matched;
			container->as.code.fence_offset = first_nonspace - offset;
			container->as.code.info = cmark_chunk_literal("");
			offset = first_nonspace + matched;

		} else if ((matched = scan_html_block_tag(&input, first_nonspace))) {

			container = add_child(parser, container, NODE_HTML, first_nonspace + 1);
			// note, we don't adjust offset because the tag is part of the text

		} else if (container->type == NODE_PARAGRAPH &&
		           (lev = scan_setext_header_line(&input, first_nonspace)) &&
		           // check that there is only one line in the paragraph:
		           cmark_strbuf_strrchr(&container->string_content, '\n',
		                                cmark_strbuf_len(&container->string_content) - 2) < 0) {

			container->type = NODE_HEADER;
			container->as.header.level = lev;
			container->as.header.setext = true;
			offset = input.len - 1;

		} else if (!(container->type == NODE_PARAGRAPH && !all_matched) &&
		           (matched = scan_hrule(&input, first_nonspace))) {

			// it's only now that we know the line is not part of a setext header:
			container = add_child(parser, container, NODE_HRULE, first_nonspace + 1);
			container = finalize(parser, container);
			offset = input.len - 1;

		} else if ((matched = parse_list_marker(&input, first_nonspace, &data))) {

			// compute padding:
			offset = first_nonspace + matched;
			i = 0;
			while (i <= 5 && peek_at(&input, offset + i) == ' ') {
				i++;
			}
			// i = number of spaces after marker, up to 5
			if (i >= 5 || i < 1 || peek_at(&input, offset) == '\n') {
				data->padding = matched + 1;
				if (i > 0) {
					offset += 1;
				}
			} else {
				data->padding = matched + i;
				offset += i;
			}

			// check container; if it's a list, see if this list item
			// can continue the list; otherwise, create a list container.

			data->marker_offset = indent;

			if (container->type != NODE_LIST ||
			    !lists_match(&container->as.list, data)) {
				container = add_child(parser, container, NODE_LIST,
				                      first_nonspace + 1);

				memcpy(&container->as.list, data, sizeof(*data));
			}

			// add the list item
			container = add_child(parser, container, NODE_ITEM,
			                      first_nonspace + 1);
			/* TODO: static */
			memcpy(&container->as.list, data, sizeof(*data));
			free(data);
		} else {
			break;
		}

		if (accepts_lines(container->type)) {
			// if it's a line container, it can't contain other containers
			break;
		}
		maybe_lazy = false;
	}

	// what remains at offset is a text line.  add the text to the
	// appropriate container.

	first_nonspace = offset;
	while (peek_at(&input, first_nonspace) == ' ')
		first_nonspace++;

	indent = first_nonspace - offset;
	blank = peek_at(&input, first_nonspace) == '\n';

	if (blank && container->last_child) {
		container->last_child->last_line_blank = true;
	}

	// block quote lines are never blank as they start with >
	// and we don't count blanks in fenced code for purposes of tight/loose
	// lists or breaking out of lists.  we also don't set last_line_blank
	// on an empty list item.
	container->last_line_blank = (blank &&
	                              container->type != NODE_BLOCK_QUOTE &&
	                              container->type != NODE_HEADER &&
	                              !(container->type == NODE_CODE_BLOCK &&
	                                container->as.code.fenced) &&
	                              !(container->type == NODE_ITEM &&
	                                container->first_child == NULL &&
	                                container->start_line == parser->line_number));

	cmark_node *cont = container;
	while (cont->parent) {
		cont->parent->last_line_blank = false;
		cont = cont->parent;
	}

	if (parser->current != last_matched_container &&
	    container == last_matched_container &&
	    !blank &&
	    parser->current->type == NODE_PARAGRAPH &&
	    cmark_strbuf_len(&parser->current->string_content) > 0) {

		add_line(parser->current, &input, offset);

	} else { // not a lazy continuation

		// finalize any blocks that were not matched and set cur to container:
		while (parser->current != last_matched_container) {
			parser->current = finalize(parser, parser->current);
			assert(parser->current != NULL);
		}

		if (container->type == NODE_CODE_BLOCK ||
		    container->type == NODE_HTML) {

			add_line(container, &input, offset);

		} else if (blank) {

			// ??? do nothing

		} else if (accepts_lines(container->type)) {

			if (container->type == NODE_HEADER &&
			    container->as.header.setext == false) {
				chop_trailing_hashtags(&input);
			}
			add_line(container, &input, first_nonspace);

		} else {
			// create paragraph container for line
			container = add_child(parser, container, NODE_PARAGRAPH, first_nonspace + 1);
			add_line(container, &input, first_nonspace);

		}

		parser->current = container;
	}
finished:
	parser->last_line_length = parser->curline->size -
	                           (parser->curline->ptr[parser->curline->size - 1] == '\n' ?
	                            1 : 0);
	;
	cmark_strbuf_clear(parser->curline);

}

cmark_node *cmark_parser_finish(cmark_parser *parser)
{
	if (parser->linebuf->size) {
		S_process_line(parser, parser->linebuf->ptr,
		               parser->linebuf->size);
		cmark_strbuf_clear(parser->linebuf);
	}

	finalize_document(parser);

	if (parser->options & CMARK_OPT_NORMALIZE) {
		cmark_consolidate_text_nodes(parser->root);
	}

	cmark_strbuf_free(parser->curline);

#if CMARK_DEBUG_NODES
	if (cmark_node_check(parser->root, stderr)) {
		abort();
	}
#endif
	return parser->root;
}