#include "grammar.h"
#include "private.h"
#include <regexp/regexp.h>
#include <regexp/format_string.h>
#include <bundles/bundles.h>
#include <oak/oak.h>

OAK_DEBUG_VAR(Parser);
OAK_DEBUG_VAR(Parser_Flow);

namespace parse
{
	std::vector< std::pair<scope::selector_t, rule_ptr> >& injected_grammars ()
	{
		static std::vector< std::pair<scope::selector_t, rule_ptr> > res;
		static bool needs_setup = true;
		if(needs_setup)
		{
			needs_setup = false;
			citerate(item, bundles::query(bundles::kFieldAny, NULL_STR, scope::wildcard, bundles::kItemTypeGrammar))
			{
				std::string injectionSelector = (*item)->value_for_field(bundles::kFieldGrammarInjectionSelector);
				if(injectionSelector != NULL_STR)
				{
					if(grammar_ptr grammar = parse_grammar(*item))
						res.push_back(std::make_pair(injectionSelector, grammar->seed()->rule));
				}
			}
		}
		return res;
	}

	size_t rule_t::rule_id_counter = 0;

	bool equal (stack_ptr lhs, stack_ptr rhs)
	{
		return lhs == rhs || lhs && rhs && *lhs == *rhs;
	}

	static bool pattern_is_format_string (std::string const& ptrn)
	{
		bool res = oak::contains(ptrn.begin(), ptrn.end(), '$');
		D(DBF_Parser, bug("%s: %s\n", ptrn.c_str(), BSTR(res)););
		return res;
	}

	static bool pattern_is_anchored (std::string const& ptrn)
	{
		bool escape = false;
		iterate(it, ptrn)
		{
			if(escape && strchr("AGz", *it))
			{
				D(DBF_Parser, bug("%s: %s\n", ptrn.c_str(), "YES"););
				return true;
			}
			escape = !escape && *it == '\\';
		}
		D(DBF_Parser, bug("%s: %s\n", ptrn.c_str(), "NO"););
		return false;
	}
	
	static regexp::pattern_t fix_anchor (regexp::pattern_t const& ptrn, size_t anchor, size_t offset, bool firstLine)
	{
		if(!pattern_is_anchored(to_s(ptrn)))
			return ptrn;

		bool escape = false;
		std::string newPatternString("");
		citerate(it, to_s(ptrn))
		{
			if(escape)
			{
				if(*it == 'A' && !firstLine)
				{
					newPatternString += NULL_STR; // we need something that can never match
				}
				else if(*it == 'G' && anchor != offset)
				{
					newPatternString += NULL_STR; // we need something that can never match
				}
				else if(*it == 'z')
				{
					newPatternString += "$(?!\n)(?<!\n)";
				}
				else
				{
					newPatternString += '\\';
					newPatternString += *it;
				}
				escape = false;
			}
			else if(*it == '\\')
			{
				escape = true;
			}
			else
			{
				newPatternString += *it;
			}
		}
		ASSERT(!escape);
		D(DBF_Parser, bug("%s → %s\n", to_s(ptrn).c_str(), newPatternString.c_str()););
		return newPatternString;
	}

	template <typename _OutputIter>
	_OutputIter escape_regexp (char const* it, char const* last, _OutputIter out)
	{
		DB(std::string tmp);
		DB(std::string org(it, last));
		static char const* special = "\\|([{}]).?*+^$";
		while(it != last)
		{
			if(strchr(special, *it))
			{
				DB(tmp += '\\');
				*out++ = '\\';
			}
			DB(tmp += *it);
			*out++ = *it++;
		}
		D(DBF_Parser, bug("%s → %s\n", org.c_str(), tmp.c_str()););
		return out;
	}

	static std::string expand_back_references (std::string const& ptrn, regexp::match_t const& m)
	{
		bool escape = false;
		std::string res;
		iterate(it, ptrn)
		{
			if(escape && isdigit(*it))
			{
				int i = digittoint(*it);
				if(!m.empty(i))
					escape_regexp(m.buffer() + m.begin(i), m.buffer() + m.end(i), back_inserter(res));
				escape = false;
				continue;
			}

			if(escape)
				res += '\\';
			if(!(escape = !escape && *it == '\\'))
				res += *it;
		}
		D(DBF_Parser, bug("%s → %s\n", ptrn.c_str(), res.c_str()););
		return res;
	}

	bool stack_t::operator== (stack_t const& rhs) const
	{
		if(*rule != *rhs.rule || scope != rhs.scope)
			return false;
		if(while_pattern != rhs.while_pattern || end_pattern != rhs.end_pattern)
			return false;
		if((!parent && rhs.parent) || (parent && (!rhs.parent || *parent != *rhs.parent)))
			return false;
		return true;
	}

	bool stack_t::operator!= (stack_t const& rhs) const
	{
		return !(*this == rhs);
	}

	struct ranked_match_t
	{
		rule_ptr rule;
		regexp::match_t match;
		size_t rank;

		WATCH_LEAKS(ranked_match_t);

		bool operator< (ranked_match_t const& rhs) const
		{
			return match.begin() == rhs.match.begin() ? rank < rhs.rank : match.begin() < rhs.match.begin();
		}
	};

	static scope::scope_t create_scope (scope::scope_t const& current_scope, std::string const& format_string, regexp::match_t const& match)
	{
		return current_scope.append(pattern_is_format_string(format_string) ? format_string::expand(format_string, match.captures()) : format_string);
	}

	static void apply_captures (scope::scope_t scope, regexp::match_t const& m, repository_ptr const& captures, std::map<size_t, scope::scope_t>& res, bool firstLine)
	{
		if(!captures)
			return;

		std::multimap<std::pair<size_t, ssize_t>, rule_ptr> rules;

		repository_t::const_iterator ruleIter = captures->begin();
		std::multimap<std::string, std::pair<size_t, size_t> >::const_iterator indexIter = m.capture_indices().begin();
		while(ruleIter != captures->end() && indexIter != m.capture_indices().end())
		{
			if(ruleIter->first == indexIter->first)
				rules.insert(std::make_pair(std::make_pair(indexIter->second.first, -(indexIter->second.second - indexIter->second.first)), ruleIter->second));

			if(ruleIter->first < indexIter->first)
					++ruleIter;
			else	++indexIter;
		}

		std::vector< std::pair<size_t, scope::scope_t> > stack;
		iterate(it, rules)
		{
			size_t from = it->first.first;
			for(; !stack.empty() && stack.back().first <= from; stack.pop_back())
				scope = res[stack.back().first] = stack.back().second;

			size_t to = it->first.first - it->first.second;
			stack.push_back(std::make_pair(to, scope));

			rule_ptr const& rule = it->second;
			if(rule->scope_string != NULL_STR)
				scope = res[from] = create_scope(scope, rule->scope_string, m);

			if(!rule->children.empty())
			{
				D(DBF_Parser, bug("re-parse: ‘%.*s’ (range %zu-%zu)\n", (int)(to - from), m.buffer() + from, from, to););
				parse::stack_ptr stack(new parse::stack_t(rule, scope));
				stack->anchor = from;
				parse(m.buffer(), m.buffer() + to, stack, res, firstLine, from);
			}
		}

		for(; !stack.empty(); stack.pop_back())
			scope = res[stack.back().first] = stack.back().second;
	}

	static size_t collect_children (rule_ptr const& base, char const* first, char const* last, size_t anchor, size_t i, bool firstLine, std::vector<rule_ptr> const& children, std::set<ranked_match_t>& res, std::map<size_t, regexp::match_t>& match_cache, std::set<size_t>& unique, size_t rank = 0);

	static size_t collect_rule (rule_ptr const& base, char const* first, char const* last, size_t anchor, size_t i, bool firstLine, rule_ptr rule, std::set<ranked_match_t>& res, std::map<size_t, regexp::match_t>& match_cache, std::set<size_t>& unique, size_t rank)
	{
		if(unique.find(rule->rule_id) != unique.end())
			return rank;

		unique.insert(rule->rule_id);
		while(rule && rule->include_string != NULL_STR)
		{
			std::string const& name = rule->include_string;
			if(rule = rule->include.lock())
			{
				if(unique.find(rule->rule_id) != unique.end())
					break;
				unique.insert(rule->rule_id);
			}
			else if(name == "$base")
			{
				rule = base;
				if(unique.find(rule->rule_id) != unique.end())
					break;
				unique.insert(rule->rule_id);
			}
			else
			{
				fprintf(stderr, "failed to resolve %s\n", name.c_str());
			}
		}

		if(!rule)
			return rank;

		if(rule->match_pattern)
		{
			D(DBF_Parser, bug("rule id %zu, pattern %s\n", rule->rule_id, to_s(rule->match_pattern).c_str()););
			std::map<size_t, regexp::match_t>::iterator it = match_cache.find(rule->rule_id);
			if(it != match_cache.end())
			{
				if(it->second)
					res.insert((ranked_match_t){ rule, it->second, ++rank });
			}
			else
			{
				regexp::match_t const& match = regexp::search(fix_anchor(rule->match_pattern, anchor, i, firstLine), first, last, first + i);
				if(!pattern_is_anchored(to_s(rule->match_pattern)))
					match_cache.insert(std::make_pair(rule->rule_id, match));
				if(match)
					res.insert((ranked_match_t){ rule, match, ++rank });
			}
		}
		else if(!rule->children.empty())
		{
			rank = collect_children(base, first, last, anchor, i, firstLine, rule->children, res, match_cache, unique, rank);
		}
		return rank;
	}

	static size_t collect_children (rule_ptr const& base, char const* first, char const* last, size_t anchor, size_t i, bool firstLine, std::vector<rule_ptr> const& children, std::set<ranked_match_t>& res, std::map<size_t, regexp::match_t>& match_cache, std::set<size_t>& unique, size_t rank)
	{
		iterate(it, children)
			rank = collect_rule(base, first, last, anchor, i, firstLine, *it, res, match_cache, unique, rank);
		return rank;
	}

	static void collect_rules (rule_ptr const& base, char const* first, char const* last, size_t i, bool firstLine, stack_ptr const& stack, std::set<ranked_match_t>& res, std::map<size_t, regexp::match_t>& match_cache)
	{
		res.clear();

		if(stack->end_pattern)
		{
			D(DBF_Parser, bug("end pattern: %s\n", to_s(stack->end_pattern).c_str()););
			if(regexp::match_t const& match = regexp::search(fix_anchor(stack->end_pattern, stack->anchor, i, firstLine), first, last, first + i))
				res.insert((ranked_match_t){ stack->rule, match, stack->apply_end_last ? SIZE_T_MAX : 0 });
		}

		std::set<size_t> unique;
		size_t rank = collect_children(base, first, last, stack->anchor, i, firstLine, stack->rule->children, res, match_cache, unique);

		for(stack_ptr node = stack; node; node = node->parent)
		{
			if(!node->rule->injections)
				continue;

			iterate(it, *node->rule->injections)
			{
				if(it->first == "." || scope::selector_t(it->first).does_match(stack->scope))
					collect_rule(base, first, last, stack->anchor, i, firstLine, it->second, res, match_cache, unique, rank);
			}
		}

		citerate(it, injected_grammars())
		{
			if(to_s(it->first) == "." || it->first.does_match(stack->scope))
				collect_children(base, first, last, stack->anchor, i, firstLine, it->second->children, res, match_cache, unique, rank);
		}
	}

	static bool has_cycle (size_t rule_id, size_t i, stack_ptr const& stack)
	{
		if(!stack->zw_begin_match || stack->anchor != i)
			return false;
		else if(rule_id == stack->rule->rule_id)
			return true;
		return stack->parent ? has_cycle(rule_id, i, stack->parent) : false;
	}

	stack_ptr parse (char const* first, char const* last, stack_ptr stack, std::map<size_t, scope::scope_t>& scopes, bool firstLine, size_t i)
	{
		D(DBF_Parser_Flow, bug("%.*s", (int)(last - first), first););

		// ==============================
		// = apply the ‘while’ patterns =
		// ==============================

		std::vector<stack_ptr> while_rules;
		for(stack_ptr node = stack; node->while_pattern; node = node->parent)
			while_rules.push_back(node);

		scope::scope_t scope = scopes[i] = while_rules.empty() ? stack->scope : while_rules.back()->parent->scope;
		D(DBF_Parser, bug("%s, offset %zu, %zu while rules\n", to_s(scope).c_str(), i, while_rules.size()););
		riterate(it, while_rules)
		{
			if(regexp::match_t const& m = regexp::search((*it)->while_pattern, first, last, first + i))
			{
				D(DBF_Parser_Flow, bug("while match %zu-%zu\n", m.begin(), m.end()););

				rule_ptr const& rule = (*it)->rule;
				if(rule->scope_string != NULL_STR)
					scope = scopes[m.begin()] = create_scope(scope, rule->scope_string, m);
				apply_captures(scope, m, rule->while_captures ?: rule->captures, scopes, firstLine);
				if(rule->content_scope_string != NULL_STR)
					scope = scopes[m.end()] = create_scope(scope, rule->content_scope_string, m);

				stack->anchor = i = m.end();
				continue;
			}

			stack = (*it)->parent;
			if(stack->while_pattern)
				stack->anchor = i;
			break;
		}

		// ======================
		// = Parse rest of line =
		// ======================

		rule_ptr base = stack->rule;
		for(stack_ptr node = stack; node; node = node->parent)
			base = node->rule;

		std::set<ranked_match_t> rules;
		std::map<size_t, regexp::match_t> match_cache;
		collect_rules(base, first, last, i, firstLine, stack, rules, match_cache);

		D(DBF_Parser, bug("%zu rules (out of %zu), parse: %.*s", rules.size(), stack->rule->children.size(), (int)(last - first - i), first + i););
		while(!rules.empty())
		{
			DB(
				D(DBF_Parser, bug("offset: %zu\n", i););
				iterate(it, rules)
					D(DBF_Parser, bug("\t%zu-%zu, %s\n", it->match.begin(), it->match.end(), to_s(it->rule->match_pattern).c_str()););
			)

			ranked_match_t m = *rules.begin();
			rules.erase(rules.begin());

			if(m.match.begin() < i)
			{
				regexp::pattern_t const& ptrn = m.rank == 0 || m.rank == SIZE_T_MAX ? stack->end_pattern : m.rule->match_pattern;
				if(m.match = regexp::search(fix_anchor(ptrn, stack->anchor, i, firstLine), first, last, first + i))
					rules.insert(m);
				continue;
			}

			i = m.match.end();
			D(DBF_Parser_Flow, bug("match %2zu-%2zu: %s\n", m.match.begin(), m.match.end(), m.rule->scope_string != NULL_STR ? m.rule->scope_string.c_str() : "(untitled)"););

			rule_ptr const& rule = m.rule;
			if(m.rank == 0 || m.rank == SIZE_T_MAX) // end-part of rule
			{
				scope = stack->scope;
				if(stack->rule->content_scope_string != NULL_STR)
					scope = scopes[m.match.begin()] = scope.parent();
				apply_captures(scope, m.match, rule->end_captures ?: rule->captures, scopes, firstLine);

				bool nothingMatched = stack->zw_begin_match && stack->anchor == i;

				stack = stack->parent;
				scope = scopes[m.match.end()] = stack->scope;
				D(DBF_Parser_Flow, bug("leaving, new scope %s\n", to_s(scope).c_str()););

				if(nothingMatched) // we left a begin/end rule but haven’t parsed any bytes, so we’re destined to repeat this mistake
				{
					fprintf(stderr, "*** no bytes parsed by rule ‘%s’, begin = ‘%s’, end = ‘%s’, position %zu for line: %.*s\n", rule->scope_string != NULL_STR ? rule->scope_string.c_str() : "(untitled)", rule->match_string.c_str(), rule->end_string.c_str(), i, (int)(last - first), first);
					break;
				}
			}
			else if(!rule->children.empty() || rule->while_string != NULL_STR || rule->end_string != NULL_STR) // begin-part of rule
			{
				if(m.match.empty() && has_cycle(rule->rule_id, i, stack))
				{
					fprintf(stderr, "*** no bytes matched and recursive include of rule ‘%s’, begin = ‘%s’, end = ‘%s’, position %zu for line: %.*s\n", rule->scope_string != NULL_STR ? rule->scope_string.c_str() : "(untitled)", rule->match_string.c_str(), rule->end_string.c_str(), i, (int)(last - first), first);
					break;
				}

				if(rule->scope_string != NULL_STR)
					scope = scopes[m.match.begin()] = create_scope(scope, rule->scope_string, m.match);
				apply_captures(scope, m.match, rule->begin_captures ?: rule->captures, scopes, firstLine);
				if(rule->content_scope_string != NULL_STR)
					scope = scopes[m.match.end()] = create_scope(scope, rule->content_scope_string, m.match);

				stack.reset(new stack_t(rule, scope, stack));
				stack->while_pattern  = rule->while_pattern;
				stack->end_pattern    = rule->end_pattern;
				stack->apply_end_last = rule->apply_end_last == "1";
				stack->anchor         = i;
				stack->zw_begin_match = m.match.empty();
				stack->parent->anchor = SIZE_T_MAX;

				if(!rule->while_pattern && rule->while_string != NULL_STR)
					stack->while_pattern = expand_back_references(rule->while_string, m.match);
				if(!rule->end_pattern && rule->end_string != NULL_STR)
					stack->end_pattern = expand_back_references(rule->end_string, m.match);
				
				D(DBF_Parser_Flow, bug("descending, new scope %s\n", to_s(scope).c_str()););
			}
			else // regular match-rule
			{
				if(m.match.empty())
				{
					fprintf(stderr, "*** no bytes parsed by rule ‘%s’, match = ‘%s’, position %zu for line: %.*s\n", rule->scope_string != NULL_STR ? rule->scope_string.c_str() : "(untitled)", rule->match_string.c_str(), i, (int)(last - first), first);
					continue; // do not re-apply since this matched zero characters
				}

				if(rule->scope_string != NULL_STR)
				{
					scope::scope_t const& newScope = create_scope(scope, rule->scope_string, m.match);
					scopes[m.match.begin()] = newScope;
					apply_captures(newScope, m.match, rule->captures, scopes, firstLine);
				}
				else
				{
					apply_captures(scope, m.match, rule->captures, scopes, firstLine);
				}
				scopes[m.match.end()] = scope;

				if(m.match = regexp::search(fix_anchor(m.rule->match_pattern, stack->anchor, i, firstLine), first, last, first + i))
					rules.insert(m);

				continue; // no context change, so skip finding rules for this context
			}

			D(DBF_Parser, bug("%zu rules before collecting\n", rules.size()););
			collect_rules(base, first, last, i, firstLine, stack, rules, match_cache);
			D(DBF_Parser, bug("%zu rules after collecting\n", rules.size()););
		}
		D(DBF_Parser_Flow, bug("line done (%zu rules)\n", rules.size()););
		stack->anchor = first + stack->anchor == last ? 0 : SIZE_T_MAX;
		return stack;
	}
}