#include "ModuleCache.h"
#include "module.h"
#include "printutils.h"
#include "openscad.h"

#include "boosty.h"
#include <boost/format.hpp>
#include <boost/filesystem.hpp>
#include <boost/foreach.hpp>

#include <stdio.h>
#include <fstream>
#include <sstream>
#include <time.h>
#include <sys/stat.h>

//#include "parsersettings.h"
/*!
	FIXME: Implement an LRU scheme to avoid having an ever-growing module cache
*/

ModuleCache *ModuleCache::inst = NULL;

/*!
	Reevaluate the given file and recompile if necessary.
	Returns NULL on any error (e.g. compile error or file not found)

	The given filename must be absolute.
*/
FileModule *ModuleCache::evaluate(const std::string &filename)
{
	FileModule *lib_mod = NULL;
	bool found = false;
	if (this->entries.find(filename) != this->entries.end()) {
		found = true;
		lib_mod = this->entries[filename].module;
	}
  
	// Don't try to recursively evaluate - if the file changes
	// during evaluation, that would be really bad.
	if (lib_mod && lib_mod->isHandlingDependencies()) return lib_mod;

	// Create cache ID
	struct stat st;
	memset(&st, 0, sizeof(struct stat));
	bool valid = (stat(filename.c_str(), &st) == 0);

	// If file isn't there, just return and let the cache retain the old module
	if (!valid) return NULL;

	// If the file is present, we'll always cache some result
	std::string cache_id = str(boost::format("%x.%x") % st.st_mtime % st.st_size);

	cache_entry &entry = this->entries[filename];
	// Initialize entry, if new
	if (!found) {
		entry.module = NULL;
		entry.cache_id = cache_id;
	}
  
	bool shouldCompile = true;
	if (found) {
		// Files should only be recompiled if the cache ID changed
		if (entry.cache_id == cache_id) {
			shouldCompile = false;
			// Recompile if includes changed
			if (lib_mod && lib_mod->includesChanged()) {
				lib_mod = NULL;
				shouldCompile = true;
			}
		}
	}

#ifdef DEBUG
	// Causes too much debug output
	//if (!shouldCompile) PRINTB("Using cached library: %s (%p)", filename % lib_mod);
#endif

	// If cache lookup failed (non-existing or old timestamp), compile module
	if (shouldCompile) {
#ifdef DEBUG
		if (found) {
			PRINTB("Recompiling cached library: %s (%s)", filename % cache_id);
		}
		else {
			PRINTB("Compiling library '%s'.", filename);
		}
#endif

		std::stringstream textbuf;
		{
			std::ifstream ifs(filename.c_str());
			if (!ifs.is_open()) {
				PRINTB("WARNING: Can't open library file '%s'\n", filename);
				return NULL;
			}
			textbuf << ifs.rdbuf();
		}
		textbuf << "\n" << commandline_commands;
		
		print_messages_push();
		
		FileModule *oldmodule = lib_mod;
		
		std::string pathname = boosty::stringy(fs::path(filename).parent_path());
		lib_mod = dynamic_cast<FileModule*>(parse(textbuf.str().c_str(), pathname.c_str(), false));
		PRINTB_NOCACHE("  compiled module: %p", lib_mod);
		
		// We defer deletion so we can ensure that the new module won't
		// have the same address as the old
		if (oldmodule) delete oldmodule;
		entry.module = lib_mod;
		entry.cache_id = cache_id;
		
		print_messages_pop();
	}
	
	if (lib_mod) lib_mod->handleDependencies();

	return lib_mod;
}

void ModuleCache::clear()
{
	this->entries.clear();
}

FileModule *ModuleCache::lookup(const std::string &filename)
{
	return isCached(filename) ? this->entries[filename].module : NULL;
}

bool ModuleCache::isCached(const std::string &filename)
{
	return this->entries.find(filename) != this->entries.end();
}