#include "agent_log.h"

#include "core/io/file_access.h"
#include "core/io/json.h"
#include "core/os/os.h"
#include "core/os/time.h"
#include "core/string/print_string.h"

// Forward declaration for SSE push.
#include "modules/agent_api/agent_server.h"

AgentLog *AgentLog::singleton = nullptr;

AgentLog::AgentLog() {
	singleton = this;

	// Register error handler to capture push_error/push_warning.
	error_handler.errfunc = _error_handler;
	error_handler.userdata = this;
	add_error_handler(&error_handler);

	// Register print handler to capture print() calls.
	print_handler.printfunc = _print_handler;
	print_handler.userdata = this;
	add_print_handler(&print_handler);
}

AgentLog::~AgentLog() {
	remove_error_handler(&error_handler);
	remove_print_handler(&print_handler);
	disable_file_sink();
	singleton = nullptr;
}

void AgentLog::_bind_methods() {
	ClassDB::bind_method(D_METHOD("log_trace", "category", "message", "data"), &AgentLog::log_trace, DEFVAL(Dictionary()));
	ClassDB::bind_method(D_METHOD("log_debug", "category", "message", "data"), &AgentLog::log_debug, DEFVAL(Dictionary()));
	ClassDB::bind_method(D_METHOD("log_info", "category", "message", "data"), &AgentLog::log_info, DEFVAL(Dictionary()));
	ClassDB::bind_method(D_METHOD("log_warn", "category", "message", "data"), &AgentLog::log_warn, DEFVAL(Dictionary()));
	ClassDB::bind_method(D_METHOD("log_error", "category", "message", "data"), &AgentLog::log_error, DEFVAL(Dictionary()));
	ClassDB::bind_method(D_METHOD("log_fatal", "category", "message", "data"), &AgentLog::log_fatal, DEFVAL(Dictionary()));
	ClassDB::bind_method(D_METHOD("get_entries", "count", "min_level", "category", "since_msec"), &AgentLog::get_entries, DEFVAL(100), DEFVAL(LEVEL_TRACE), DEFVAL(""), DEFVAL(0));
	ClassDB::bind_method(D_METHOD("get_entry_count"), &AgentLog::get_entry_count);
	ClassDB::bind_method(D_METHOD("set_min_level", "level"), &AgentLog::set_min_level);
	ClassDB::bind_method(D_METHOD("get_min_level"), &AgentLog::get_min_level);
	ClassDB::bind_method(D_METHOD("enable_file_sink", "path"), &AgentLog::enable_file_sink);
	ClassDB::bind_method(D_METHOD("disable_file_sink"), &AgentLog::disable_file_sink);
	ClassDB::bind_method(D_METHOD("clear"), &AgentLog::clear);

	BIND_ENUM_CONSTANT(LEVEL_TRACE);
	BIND_ENUM_CONSTANT(LEVEL_DEBUG);
	BIND_ENUM_CONSTANT(LEVEL_INFO);
	BIND_ENUM_CONSTANT(LEVEL_WARN);
	BIND_ENUM_CONSTANT(LEVEL_ERROR);
	BIND_ENUM_CONSTANT(LEVEL_FATAL);
}

// --- Logging Methods ---

void AgentLog::log_trace(const String &p_category, const String &p_message, const Dictionary &p_data) {
	log_message(LEVEL_TRACE, p_category, p_message, p_data);
}

void AgentLog::log_debug(const String &p_category, const String &p_message, const Dictionary &p_data) {
	log_message(LEVEL_DEBUG, p_category, p_message, p_data);
}

void AgentLog::log_info(const String &p_category, const String &p_message, const Dictionary &p_data) {
	log_message(LEVEL_INFO, p_category, p_message, p_data);
}

void AgentLog::log_warn(const String &p_category, const String &p_message, const Dictionary &p_data) {
	log_message(LEVEL_WARN, p_category, p_message, p_data);
}

void AgentLog::log_error(const String &p_category, const String &p_message, const Dictionary &p_data) {
	log_message(LEVEL_ERROR, p_category, p_message, p_data);
}

void AgentLog::log_fatal(const String &p_category, const String &p_message, const Dictionary &p_data) {
	log_message(LEVEL_FATAL, p_category, p_message, p_data);
}

void AgentLog::log_message(Level p_level, const String &p_category, const String &p_message, const Dictionary &p_data) {
	if (p_level < min_level) {
		return;
	}

	LogEntry entry;
	entry.timestamp_msec = OS::get_singleton()->get_ticks_msec();
	entry.level = p_level;
	entry.category = p_category;
	entry.message = p_message;
	entry.data = p_data;

	_write_entry(entry);
}

void AgentLog::_write_entry(const LogEntry &p_entry) {
	LogEntry entry = p_entry;

	{
		MutexLock lock(buffer_mutex);
		entry.id = next_id++;
		ring_buffer[write_pos] = entry;
		write_pos = (write_pos + 1) % RING_BUFFER_SIZE;
		if (entry_count < RING_BUFFER_SIZE) {
			entry_count++;
		}
	}

	// Write to file sink.
	if (file_sink_enabled) {
		_write_to_file(entry);
	}

	// Push to SSE clients via AgentServer.
	AgentServer *server = AgentServer::get_singleton();
	if (server && server->is_running()) {
		Dictionary dict = _entry_to_dict(entry);
		server->push_sse("logs", "log", JSON::stringify(dict));
	}
}

void AgentLog::_write_to_file(const LogEntry &p_entry) {
	if (file_sink.is_null()) {
		return;
	}
	Dictionary dict = _entry_to_dict(p_entry);
	String line = JSON::stringify(dict) + "\n";
	file_sink->store_string(line);
	file_sink->flush();
}

// --- Error/Print Hooks ---

void AgentLog::_error_handler(void *p_self, const char *p_func, const char *p_file, int p_line, const char *p_error, const char *p_errorexp, bool p_editor_notify, ErrorHandlerType p_type) {
	AgentLog *self = static_cast<AgentLog *>(p_self);

	Level level;
	String category = "engine";
	switch (p_type) {
		case ERR_HANDLER_ERROR:
			level = LEVEL_ERROR;
			break;
		case ERR_HANDLER_WARNING:
			level = LEVEL_WARN;
			break;
		default:
			level = LEVEL_INFO;
			break;
	}

	String message = String::utf8(p_error);
	if (p_errorexp && p_errorexp[0]) {
		message += ": " + String::utf8(p_errorexp);
	}

	Dictionary data;
	data["function"] = String::utf8(p_func);
	data["file"] = String::utf8(p_file);
	data["line"] = p_line;

	self->log_message(level, category, message, data);
}

void AgentLog::_print_handler(void *p_self, const String &p_string, bool p_error, bool p_rich) {
	AgentLog *self = static_cast<AgentLog *>(p_self);

	// Don't re-log our own output.
	if (p_string.begins_with("AgentLog:") || p_string.begins_with("AgentServer:")) {
		return;
	}

	Level level = p_error ? LEVEL_ERROR : LEVEL_DEBUG;
	self->log_message(level, "print", p_string, Dictionary());
}

// --- Query ---

Array AgentLog::get_entries(int p_count, Level p_min_level, const String &p_category, uint64_t p_since_msec) {
	Array result;
	MutexLock lock(buffer_mutex);

	int start = (entry_count < RING_BUFFER_SIZE) ? 0 : write_pos;
	int count = entry_count;

	// Walk the ring buffer from newest to oldest.
	for (int i = count - 1; i >= 0 && result.size() < p_count; i--) {
		int idx = (start + i) % RING_BUFFER_SIZE;
		const LogEntry &entry = ring_buffer[idx];

		if (entry.level < p_min_level) {
			continue;
		}
		if (!p_category.is_empty() && entry.category != p_category) {
			continue;
		}
		if (p_since_msec > 0 && entry.timestamp_msec < p_since_msec) {
			break; // Entries are ordered by time.
		}

		result.push_back(_entry_to_dict(entry));
	}

	return result;
}

// --- File Sink ---

void AgentLog::enable_file_sink(const String &p_path) {
	disable_file_sink();
	file_sink = FileAccess::open(p_path, FileAccess::WRITE);
	if (file_sink.is_valid()) {
		file_sink_enabled = true;
		file_sink_path = p_path;
	}
}

void AgentLog::disable_file_sink() {
	file_sink_enabled = false;
	file_sink.unref();
}

void AgentLog::clear() {
	MutexLock lock(buffer_mutex);
	write_pos = 0;
	entry_count = 0;
}

// --- Utilities ---

String AgentLog::_level_string(Level p_level) {
	switch (p_level) {
		case LEVEL_TRACE: return "trace";
		case LEVEL_DEBUG: return "debug";
		case LEVEL_INFO: return "info";
		case LEVEL_WARN: return "warn";
		case LEVEL_ERROR: return "error";
		case LEVEL_FATAL: return "fatal";
		default: return "unknown";
	}
}

Dictionary AgentLog::_entry_to_dict(const LogEntry &p_entry) {
	Dictionary dict;
	dict["id"] = p_entry.id;
	dict["timestamp_msec"] = p_entry.timestamp_msec;
	dict["level"] = _level_string(p_entry.level);
	dict["category"] = p_entry.category;
	dict["message"] = p_entry.message;
	if (!p_entry.data.is_empty()) {
		dict["data"] = p_entry.data;
	}
	return dict;
}