/*
    Ousía
    Copyright (C) 2014, 2015  Benjamin Paaßen, Andreas Stöckel

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <core/common/Exceptions.hpp>
#include <core/common/Utils.hpp>
#include <core/model/Typesystem.hpp>

#include "ParserScope.hpp"

namespace ousia {

/* Class ParserScopeBase */

ParserScopeBase::ParserScopeBase() {}

ParserScopeBase::ParserScopeBase(const NodeVector<Node> &nodes) : nodes(nodes)
{
}

Rooted<Node> ParserScopeBase::resolve(const Rtti &type,
                                      const std::vector<std::string> &path,
                                      Logger &logger)
{
	// Go up the stack and try to resolve the
	for (auto it = nodes.rbegin(); it != nodes.rend(); it++) {
		std::vector<ResolutionResult> res = (*it)->resolve(type, path);

		// Abort if the object could not be resolved
		if (res.empty()) {
			continue;
		}

		// Log an error if the object is not unique
		if (res.size() > 1) {
			logger.error(std::string("The reference \"") +
			             Utils::join(path, ".") + ("\" is ambigous!"));
			logger.note("Referenced objects are:", SourceLocation{},
			            MessageMode::NO_CONTEXT);
			for (const ResolutionResult &r : res) {
				logger.note(Utils::join(r.path(), "."), *(r.node));
			}
		}
		return res[0].node;
	}
	return nullptr;
}

/* Class DeferredResolution */

DeferredResolution::DeferredResolution(const NodeVector<Node> &nodes,
                                       const std::vector<std::string> &path,
                                       const Rtti &type,
                                       ResolutionResultCallback resultCallback,
                                       Handle<Node> owner)
    : scope(nodes),
      resultCallback(resultCallback),
      path(path),
      type(type),
      owner(owner)
{
}

bool DeferredResolution::resolve(
    const std::unordered_multiset<const Node *> &ignore, Logger &logger)
{
	// Fork the logger to prevent error messages from being shown if we actively
	// ignore the resolution result
	LoggerFork loggerFork = logger.fork();
	Rooted<Node> res = scope.resolve(type, path, loggerFork);
	if (res != nullptr) {
		if (!ignore.count(res.get())) {
			loggerFork.commit();
			try {
				// Push the location onto the logger default location stack
				GuardedLogger loggerGuard(logger, *owner);
				resultCallback(res, owner, logger);
			}
			catch (LoggableException ex) {
				logger.log(ex);
			}
			return true;
		}
	} else {
		loggerFork.commit();
	}
	return false;
}

void DeferredResolution::fail(Logger &logger)
{
	try {
		resultCallback(nullptr, owner, logger);
	}
	catch (LoggableException ex) {
		logger.log(ex);
	}
}

/* Class ParserScope */

ParserScope::ParserScope(const NodeVector<Node> &nodes,
                         const std::vector<ParserFlagDescriptor> &flags)
    : ParserScopeBase(nodes), flags(flags), topLevelDepth(nodes.size())
{
}

ParserScope::ParserScope() : topLevelDepth(0) {}

bool ParserScope::checkUnwound(Logger &logger) const
{
	if (nodes.size() != topLevelDepth) {
		logger.error("Not all open elements have been closed!",
		             SourceLocation{}, MessageMode::NO_CONTEXT);
		logger.note("Still open elements are: ", SourceLocation{},
		            MessageMode::NO_CONTEXT);
		for (size_t i = topLevelDepth + 1; i < nodes.size(); i++) {
			logger.note(std::string("Element of interal type ") +
			                nodes[i]->type().name +
			                std::string(" defined here:"),
			            *nodes[i]);
		}
		return false;
	}
	return true;
}

ParserScope ParserScope::fork() { return ParserScope{nodes, flags}; }

bool ParserScope::join(const ParserScope &fork, Logger &logger)
{
	// Make sure the fork has been unwound
	if (!fork.checkUnwound(logger)) {
		return false;
	}

	// Insert the deferred resolutions of the fork into our own deferred
	// resolution list
	deferred.insert(deferred.end(), fork.deferred.begin(), fork.deferred.end());
	awaitingResolution.insert(fork.awaitingResolution.begin(),
	                          fork.awaitingResolution.end());
	return true;
}

void ParserScope::push(Handle<Node> node)
{
	const size_t currentDepth = nodes.size();
	if (currentDepth == topLevelDepth) {
		topLevelNodes.push_back(node);
	}
	nodes.push_back(node);
}

void ParserScope::pop()
{
	// Make sure pop is not called without an element on the stack
	const size_t currentDepth = nodes.size();
	if (currentDepth == topLevelDepth) {
		throw LoggableException{"No element here to end!"};
	}

	// Remove all flags from the stack that were set for higher stack depths.
	size_t newLen = 0;
	for (ssize_t i = flags.size() - 1; i >= 0; i--) {
		if (flags[i].depth < currentDepth) {
			newLen = i + 1;
			break;
		}
	}
	flags.resize(newLen);

	// Remove the element from the stack
	nodes.pop_back();
}

NodeVector<Node> ParserScope::getTopLevelNodes() const { return topLevelNodes; }

Rooted<Node> ParserScope::getRoot() const { return nodes.front(); }

Rooted<Node> ParserScope::getLeaf() const { return nodes.back(); }

Rooted<Node> ParserScope::select(RttiSet types, int maxDepth)
{
	ssize_t minDepth = 0;
	if (maxDepth >= 0) {
		minDepth = static_cast<ssize_t>(nodes.size()) - (maxDepth + 1);
	}
	for (ssize_t i = nodes.size() - 1; i >= minDepth; i--) {
		if (nodes[i]->type().isOneOf(types)) {
			return nodes[i];
		}
	}
	return nullptr;
}

void ParserScope::setFlag(ParserFlag flag, bool value)
{
	// Fetch the current stack depth
	const size_t currentDepth = nodes.size();

	// Try to change the value of the flag if it was already set on the same
	// stack depth
	for (auto it = flags.rbegin(); it != flags.rend(); it++) {
		if (it->depth == currentDepth) {
			if (it->flag == flag) {
				it->value = value;
				return;
			}
		} else {
			break;
		}
	}

	// Insert a new element into the flags list
	flags.emplace_back(currentDepth, flag, value);
}

bool ParserScope::getFlag(ParserFlag flag)
{
	for (auto it = flags.crbegin(); it != flags.crend(); it++) {
		if (it->flag == flag) {
			return it->value;
		}
	}
	return false;
}

bool ParserScope::resolve(const Rtti &type,
                          const std::vector<std::string> &path,
                          Handle<Node> owner, Logger &logger,
                          ResolutionImposterCallback imposterCallback,
                          ResolutionResultCallback resultCallback)
{
	if (!resolve(type, path, owner, logger, resultCallback)) {
		resultCallback(imposterCallback(), owner, logger);
		return false;
	}
	return true;
}

bool ParserScope::resolve(const Rtti &type,
                          const std::vector<std::string> &path,
                          Handle<Node> owner, Logger &logger,
                          ResolutionResultCallback resultCallback)
{
	// Try to directly resolve the node
	Rooted<Node> res = ParserScopeBase::resolve(type, path, logger);
	if (res != nullptr && !awaitingResolution.count(res.get())) {
		try {
			resultCallback(res, owner, logger);
		}
		catch (LoggableException ex) {
			logger.log(ex, *owner);
		}
		return true;
	}

	// Mark the owner as "awaitingResolution", preventing it from being returned
	// as resolution result
	if (owner != nullptr) {
		awaitingResolution.insert(owner.get());
	}
	deferred.emplace_back(nodes, path, type, resultCallback, owner);
	return false;
}

bool ParserScope::resolveType(const std::vector<std::string> &path,
                              Handle<Node> owner, Logger &logger,
                              ResolutionResultCallback resultCallback)
{
	// Check whether the given path denotes an array, if yes recursively resolve
	// the inner type and wrap it in an array type (this allows multi
	// dimensional arrays).
	if (!path.empty()) {
		const std::string &last = path.back();
		if (last.size() >= 2 && last.substr(last.size() - 2, 2) == "[]") {
			// Type ends with "[]", remove this from the last element in the
			// list
			std::vector<std::string> p = path;
			p.back() = p.back().substr(0, last.size() - 2);

			// Resolve the rest of the type
			return resolveType(p, owner, logger,
			                   [resultCallback](Handle<Node> resolved,
			                                    Handle<Node> owner,
			                                    Logger &logger) {
				if (resolved != nullptr) {
					Rooted<ArrayType> arr{new ArrayType{resolved.cast<Type>()}};
					resultCallback(arr, owner, logger);
				} else {
					resultCallback(nullptr, owner, logger);
				}
			});
		}
	}

	// Requested type is not an array, call the usual resolve function
	return resolve(RttiTypes::Type, path, owner, logger, resultCallback);
}

bool ParserScope::resolveType(const std::string &name, Handle<Node> owner,
                              Logger &logger,
                              ResolutionResultCallback resultCallback)
{
	return resolveType(Utils::split(name, '.'), owner, logger, resultCallback);
}

bool ParserScope::resolveTypeWithValue(const std::vector<std::string> &path,
                                       Handle<Node> owner, Variant &value,
                                       Logger &logger,
                                       ResolutionResultCallback resultCallback)
{
	// Fork the parser scope -- constants need to be resolved in the same
	// context as this resolve call
	std::shared_ptr<ParserScope> scope = std::make_shared<ParserScope>(fork());

	return resolveType(
	    path, owner, logger,
	    [=](Handle<Node> resolved, Handle<Node> owner, Logger &logger) mutable {
		    // Abort if the lookup failed
		    if (resolved == nullptr) {
			    resultCallback(resolved, owner, logger);
			    return;
		    }

		    // Fetch the type reference and the manager reference
		    Rooted<Type> type = resolved.cast<Type>();
		    Manager *mgr = &type->getManager();

		    // The type has been resolved, try to resolve magic values as
		    // constants and postpone calling the callback function until
		    // all magic values have been resolved
		    std::shared_ptr<bool> isAsync = std::make_shared<bool>(false);
		    std::shared_ptr<int> magicCount = std::make_shared<int>(0);
		    type->build(value, logger, [=](Variant &magicValue, bool isValid,
		                                   ManagedUid innerTypeUid) mutable {
			    // Fetch the inner type
			    Rooted<Type> innerType =
			        dynamic_cast<Type *>(mgr->getManaged(innerTypeUid));
			    if (innerType == nullptr) {
				    return;
			    }

			    // Fetch a pointer at the variant
			    Variant *magicValuePtr = &magicValue;

			    // Increment the number of encountered magic values
			    (*magicCount)++;

			    // Try to resolve the value as constant
			    std::string constantName = magicValue.asMagic();
			    scope->resolve<Constant>(constantName, owner, logger,
			                             [=](Handle<Node> resolved,
			                                 Handle<Node> owner,
			                                 Logger &logger) mutable {
				    if (resolved != nullptr) {
					    // Make sure the constant is of the correct inner type
					    Rooted<Constant> constant = resolved.cast<Constant>();
					    Rooted<Type> constantType = constant->getType();
					    if (constantType != innerType) {
						    logger.error(
						        std::string("Expected value of type \"") +
						            innerType->getName() +
						            std::string("\" but found constant \"") +
						            constant->getName() +
						            std::string(" of type \"") +
						            constantType->getName() + "\" instead.",
						        *owner);
					    } else if (!isValid) {
						    logger.error("Identifier \"" + constantName +
						                     "\" is not a valid " +
						                     innerType->getName(),
						                 *owner);
					    }

					    // Nevertheless, no matter what happened, set the value
					    // of the original magic variant to the given constant
					    *magicValuePtr = constant->getValue();
				    }

				    // Decrement the number of magic values, call the callback
				    // function if all magic values have been resolved
				    (*magicCount)--;
				    if ((*magicCount) == 0 && (*isAsync)) {
					    resultCallback(resolved, owner, logger);
				    }
				});
			});

		    // Now we are asynchronous
		    (*isAsync) = true;

		    // Directly call the callback function if there were no magic values
		    // involved
		    if ((*magicCount) == 0) {
			    resultCallback(resolved, owner, logger);
		    }
		});
}

bool ParserScope::resolveTypeWithValue(const std::string &name,
                                       Handle<Node> owner, Variant &value,
                                       Logger &logger,
                                       ResolutionResultCallback resultCallback)
{
	return resolveTypeWithValue(Utils::split(name, '.'), owner, value, logger,
	                            resultCallback);
}

bool ParserScope::performDeferredResolution(Logger &logger)
{
	// Repeat the resolution process as long as something has changed in the
	// last iteration (resolving a node may cause other nodes to be resolvable).
	while (true) {
		// Iterate over all deferred resolution processes,
		bool hasChange = false;
		for (auto it = deferred.begin(); it != deferred.end();) {
			if (it->resolve(awaitingResolution, logger)) {
				if (it->owner != nullptr) {
					awaitingResolution.erase(it->owner.get());
				}
				it = deferred.erase(it);
				hasChange = true;
			} else {
				it++;
			}
		}

		// Abort if nothing has changed in the last iteration
		if (!hasChange) {
			// In a last step, clear the "awaitingResolution" list to allow
			// cyclical dependencies to be resolved
			if (!awaitingResolution.empty()) {
				awaitingResolution.clear();
			} else {
				break;
			}
		}
	}

	// We were successful if there are no more deferred resolutions
	if (deferred.empty()) {
		return true;
	}

	// Output error messages for all elements for which resolution did not
	// succeed.
	for (auto &failed : deferred) {
		failed.fail(logger);
		logger.error(std::string("Could not resolve ") + failed.type.name +
		                 std::string(" \"") + Utils::join(failed.path, ".") +
		                 std::string("\""),
		             *failed.owner);
	}
	deferred.clear();
	return false;
}
}