#include "agent_analytics.h"

#include "core/config/engine.h"
#include "core/io/file_access.h"
#include "core/io/json.h"
#include "core/os/os.h"
#include "core/string/print_string.h"
#include "core/math/math_funcs.h"

AgentAnalytics *AgentAnalytics::singleton = nullptr;

AgentAnalytics::AgentAnalytics() {
	singleton = this;
}

AgentAnalytics::~AgentAnalytics() {
	singleton = nullptr;
}

void AgentAnalytics::_bind_methods() {
	// Event tracking.
	ClassDB::bind_method(D_METHOD("capture", "event", "properties"), &AgentAnalytics::capture, DEFVAL(Dictionary()));
	ClassDB::bind_method(D_METHOD("identify", "distinct_id", "properties"), &AgentAnalytics::identify, DEFVAL(Dictionary()));
	ClassDB::bind_method(D_METHOD("screen", "screen_name", "properties"), &AgentAnalytics::screen, DEFVAL(Dictionary()));
	ClassDB::bind_method(D_METHOD("start_session", "distinct_id"), &AgentAnalytics::start_session, DEFVAL(""));
	ClassDB::bind_method(D_METHOD("end_session"), &AgentAnalytics::end_session);
	ClassDB::bind_method(D_METHOD("get_session_id"), &AgentAnalytics::get_session_id);

	// Feature flags.
	ClassDB::bind_method(D_METHOD("is_feature_enabled", "key", "context"), &AgentAnalytics::is_feature_enabled, DEFVAL(Dictionary()));
	ClassDB::bind_method(D_METHOD("get_feature_flag", "key", "default"), &AgentAnalytics::get_feature_flag, DEFVAL(Variant()));
	ClassDB::bind_method(D_METHOD("set_feature_flag", "key", "enabled", "value", "rollout", "description"), &AgentAnalytics::set_feature_flag, DEFVAL(Variant()), DEFVAL(100.0f), DEFVAL(""));
	ClassDB::bind_method(D_METHOD("remove_feature_flag", "key"), &AgentAnalytics::remove_feature_flag);
	ClassDB::bind_method(D_METHOD("get_all_flags"), &AgentAnalytics::get_all_flags);
	ClassDB::bind_method(D_METHOD("load_flags_from_file", "path"), &AgentAnalytics::load_flags_from_file, DEFVAL("res://feature_flags.json"));
	ClassDB::bind_method(D_METHOD("save_flags_to_file", "path"), &AgentAnalytics::save_flags_to_file, DEFVAL("res://feature_flags.json"));

	// A/B testing.
	ClassDB::bind_method(D_METHOD("get_experiment_group", "experiment_key", "groups"), &AgentAnalytics::get_experiment_group);
	ClassDB::bind_method(D_METHOD("get_experiment_results", "experiment_key"), &AgentAnalytics::get_experiment_results);

	// Funnels.
	ClassDB::bind_method(D_METHOD("define_funnel", "name", "steps"), &AgentAnalytics::define_funnel);
	ClassDB::bind_method(D_METHOD("get_funnel_stats", "name"), &AgentAnalytics::get_funnel_stats);

	// Query.
	ClassDB::bind_method(D_METHOD("get_events", "count", "event_name", "since_msec"), &AgentAnalytics::get_events, DEFVAL(100), DEFVAL(""), DEFVAL(0));
	ClassDB::bind_method(D_METHOD("get_event_count", "event_name"), &AgentAnalytics::get_event_count, DEFVAL(""));
	ClassDB::bind_method(D_METHOD("get_event_counts_by_name"), &AgentAnalytics::get_event_counts_by_name);

	// Config.
	ClassDB::bind_method(D_METHOD("enable_file_sink", "path"), &AgentAnalytics::enable_file_sink, DEFVAL("user://analytics.jsonl"));
	ClassDB::bind_method(D_METHOD("disable_file_sink"), &AgentAnalytics::disable_file_sink);
	ClassDB::bind_method(D_METHOD("set_remote_endpoint", "endpoint", "api_key"), &AgentAnalytics::set_remote_endpoint);
	ClassDB::bind_method(D_METHOD("disable_remote"), &AgentAnalytics::disable_remote);
	ClassDB::bind_method(D_METHOD("set_distinct_id", "id"), &AgentAnalytics::set_distinct_id);
	ClassDB::bind_method(D_METHOD("get_distinct_id"), &AgentAnalytics::get_distinct_id);

	// Super properties.
	ClassDB::bind_method(D_METHOD("set_super_property", "key", "value"), &AgentAnalytics::set_super_property);
	ClassDB::bind_method(D_METHOD("remove_super_property", "key"), &AgentAnalytics::remove_super_property);
	ClassDB::bind_method(D_METHOD("clear_super_properties"), &AgentAnalytics::clear_super_properties);
	ClassDB::bind_method(D_METHOD("clear"), &AgentAnalytics::clear);
}

// --- Event Tracking ---

void AgentAnalytics::capture(const String &p_event, const Dictionary &p_properties) {
	AnalyticsEvent evt;
	evt.timestamp_msec = OS::get_singleton()->get_ticks_msec();
	evt.event_name = p_event;
	evt.distinct_id = current_distinct_id;
	evt.properties = p_properties;

	// Merge super properties.
	for (const Variant &key : super_properties.keys()) {
		if (!evt.properties.has(key)) {
			evt.properties[key] = super_properties[key];
		}
	}

	// Add session info.
	if (!current_session_id.is_empty()) {
		evt.properties["$session_id"] = current_session_id;
	}

	{
		MutexLock lock(events_mutex);
		evt.id = next_event_id++;
		events.push_back(evt);
		if (events.size() > EVENT_BUFFER_SIZE) {
			events.remove_at(0);
		}
	}

	// Update funnel tracking.
	for (KeyValue<String, Funnel> &kv : funnels) {
		Array steps = kv.value.steps;
		for (int i = 0; i < steps.size(); i++) {
			if (String(steps[i]) == p_event) {
				String step_key = vformat("step_%d_%s", i, p_event);
				int count = kv.value.step_counts.has(step_key) ? (int)kv.value.step_counts[step_key] : 0;
				kv.value.step_counts[step_key] = count + 1;
			}
		}
	}

	// Write to file sink.
	if (file_sink_enabled) {
		_write_event_to_file(evt);
	}

	// Send to remote.
	if (remote_enabled) {
		_send_event_to_remote(evt);
	}
}

void AgentAnalytics::identify(const String &p_distinct_id, const Dictionary &p_properties) {
	current_distinct_id = p_distinct_id;
	Dictionary props = p_properties;
	props["$set"] = p_properties;
	capture("$identify", props);
}

void AgentAnalytics::alias(const String &p_alias, const String &p_distinct_id) {
	Dictionary props;
	props["alias"] = p_alias;
	props["distinct_id"] = p_distinct_id;
	capture("$create_alias", props);
}

void AgentAnalytics::screen(const String &p_screen_name, const Dictionary &p_properties) {
	Dictionary props = p_properties;
	props["$screen_name"] = p_screen_name;
	capture("$screen", props);
}

// --- Session ---

void AgentAnalytics::start_session(const String &p_distinct_id) {
	if (!p_distinct_id.is_empty()) {
		current_distinct_id = p_distinct_id;
	}
	current_session_id = _generate_session_id();
	session_start = OS::get_singleton()->get_ticks_msec();

	Dictionary props;
	props["$session_id"] = current_session_id;
	capture("$session_start", props);
}

void AgentAnalytics::end_session() {
	if (current_session_id.is_empty()) {
		return;
	}

	Dictionary props;
	props["$session_id"] = current_session_id;
	props["$session_duration_ms"] = OS::get_singleton()->get_ticks_msec() - session_start;
	capture("$session_end", props);

	current_session_id = "";
}

// --- Feature Flags ---

bool AgentAnalytics::is_feature_enabled(const String &p_key, const Dictionary &p_context) {
	MutexLock lock(flags_mutex);
	if (!feature_flags.has(p_key)) {
		return false;
	}

	const FeatureFlag &flag = feature_flags[p_key];
	if (!flag.enabled) {
		return false;
	}

	// Rollout percentage check.
	if (flag.rollout_percentage < 100.0f) {
		// Deterministic hash based on distinct_id + flag key for consistent assignment.
		String hash_input = current_distinct_id + ":" + p_key;
		uint32_t hash = hash_input.hash();
		float percentage = (float)(hash % 10000) / 100.0f;
		if (percentage >= flag.rollout_percentage) {
			return false;
		}
	}

	// Condition evaluation.
	if (!flag.conditions.is_empty()) {
		return _evaluate_flag_conditions(flag, p_context);
	}

	return true;
}

Variant AgentAnalytics::get_feature_flag(const String &p_key, const Variant &p_default) {
	MutexLock lock(flags_mutex);
	if (!feature_flags.has(p_key)) {
		return p_default;
	}
	const FeatureFlag &flag = feature_flags[p_key];
	if (!flag.enabled) {
		return p_default;
	}
	return flag.value.get_type() != Variant::NIL ? flag.value : p_default;
}

void AgentAnalytics::set_feature_flag(const String &p_key, bool p_enabled, const Variant &p_value, float p_rollout, const String &p_description) {
	MutexLock lock(flags_mutex);
	FeatureFlag flag;
	flag.key = p_key;
	flag.enabled = p_enabled;
	flag.value = p_value;
	flag.rollout_percentage = p_rollout;
	flag.description = p_description;
	feature_flags[p_key] = flag;

	// Track the flag change.
	Dictionary props;
	props["flag_key"] = p_key;
	props["enabled"] = p_enabled;
	props["rollout"] = p_rollout;
	capture("$feature_flag_changed", props);
}

void AgentAnalytics::remove_feature_flag(const String &p_key) {
	MutexLock lock(flags_mutex);
	feature_flags.erase(p_key);
}

Array AgentAnalytics::get_all_flags() const {
	Array result;
	for (const KeyValue<String, FeatureFlag> &kv : feature_flags) {
		Dictionary dict;
		dict["key"] = kv.value.key;
		dict["enabled"] = kv.value.enabled;
		dict["value"] = kv.value.value;
		dict["rollout_percentage"] = kv.value.rollout_percentage;
		dict["description"] = kv.value.description;
		result.push_back(dict);
	}
	return result;
}

bool AgentAnalytics::load_flags_from_file(const String &p_path) {
	if (!FileAccess::exists(p_path)) {
		return false;
	}

	Ref<FileAccess> file = FileAccess::open(p_path, FileAccess::READ);
	if (file.is_null()) {
		return false;
	}

	Variant parsed = JSON::parse_string(file->get_as_text());
	if (parsed.get_type() != Variant::DICTIONARY) {
		return false;
	}

	Dictionary data = parsed;
	MutexLock lock(flags_mutex);

	for (const Variant &key : data.keys()) {
		Dictionary flag_data = data[key];
		FeatureFlag flag;
		flag.key = key;
		flag.enabled = flag_data.get("enabled", false);
		flag.value = flag_data.get("value", Variant());
		flag.rollout_percentage = flag_data.get("rollout_percentage", 100.0f);
		flag.description = flag_data.get("description", "");
		feature_flags[String(key)] = flag;
	}

	print_line(vformat("AgentAnalytics: Loaded %d feature flags from '%s'", data.size(), p_path));
	return true;
}

bool AgentAnalytics::save_flags_to_file(const String &p_path) {
	Ref<FileAccess> file = FileAccess::open(p_path, FileAccess::WRITE);
	if (file.is_null()) {
		return false;
	}

	Dictionary data;
	MutexLock lock(flags_mutex);
	for (const KeyValue<String, FeatureFlag> &kv : feature_flags) {
		Dictionary flag_dict;
		flag_dict["enabled"] = kv.value.enabled;
		flag_dict["value"] = kv.value.value;
		flag_dict["rollout_percentage"] = kv.value.rollout_percentage;
		flag_dict["description"] = kv.value.description;
		data[kv.key] = flag_dict;
	}

	file->store_string(JSON::stringify(data, "\t"));
	return true;
}

// --- A/B Testing ---

String AgentAnalytics::get_experiment_group(const String &p_experiment_key, const Array &p_groups) {
	if (experiment_groups.has(p_experiment_key)) {
		return experiment_groups[p_experiment_key];
	}

	if (p_groups.is_empty()) {
		return "";
	}

	// Deterministic assignment based on distinct_id + experiment key.
	String hash_input = current_distinct_id + ":" + p_experiment_key;
	uint32_t hash = hash_input.hash();
	int group_idx = hash % p_groups.size();
	String group = p_groups[group_idx];

	experiment_groups[p_experiment_key] = group;

	// Track assignment.
	Dictionary props;
	props["experiment"] = p_experiment_key;
	props["group"] = group;
	capture("$experiment_assigned", props);

	return group;
}

Dictionary AgentAnalytics::get_experiment_results(const String &p_experiment_key) {
	Dictionary results;
	results["experiment"] = p_experiment_key;

	// Count events per group.
	Dictionary group_counts;
	MutexLock lock(events_mutex);
	for (const AnalyticsEvent &evt : events) {
		if (evt.properties.has("experiment") && String(evt.properties["experiment"]) == p_experiment_key) {
			String group = evt.properties.get("group", "unknown");
			int count = group_counts.has(group) ? (int)group_counts[group] : 0;
			group_counts[group] = count + 1;
		}
	}

	results["group_counts"] = group_counts;
	return results;
}

// --- Funnels ---

void AgentAnalytics::define_funnel(const String &p_name, const Array &p_steps) {
	Funnel funnel;
	funnel.name = p_name;
	funnel.steps = p_steps;
	funnels[p_name] = funnel;
}

Dictionary AgentAnalytics::get_funnel_stats(const String &p_name) {
	Dictionary result;
	if (!funnels.has(p_name)) {
		result["error"] = "Funnel not found";
		return result;
	}

	const Funnel &funnel = funnels[p_name];
	result["name"] = funnel.name;
	result["steps"] = funnel.steps;
	result["step_counts"] = funnel.step_counts;

	// Calculate conversion rates.
	Array conversions;
	for (int i = 0; i < funnel.steps.size(); i++) {
		String step_key = vformat("step_%d_%s", i, String(funnel.steps[i]));
		int count = funnel.step_counts.has(step_key) ? (int)funnel.step_counts[step_key] : 0;

		Dictionary step_info;
		step_info["step"] = funnel.steps[i];
		step_info["count"] = count;
		if (i > 0) {
			String prev_key = vformat("step_%d_%s", i - 1, String(funnel.steps[i - 1]));
			int prev_count = funnel.step_counts.has(prev_key) ? (int)funnel.step_counts[prev_key] : 0;
			step_info["conversion_rate"] = prev_count > 0 ? (float)count / (float)prev_count * 100.0f : 0.0f;
		}
		conversions.push_back(step_info);
	}
	result["conversions"] = conversions;

	return result;
}

// --- Query ---

Array AgentAnalytics::get_events(int p_count, const String &p_event_name, uint64_t p_since_msec) {
	Array result;
	MutexLock lock(events_mutex);

	for (int i = events.size() - 1; i >= 0 && result.size() < p_count; i--) {
		const AnalyticsEvent &evt = events[i];

		if (!p_event_name.is_empty() && evt.event_name != p_event_name) {
			continue;
		}
		if (p_since_msec > 0 && evt.timestamp_msec < p_since_msec) {
			break;
		}

		Dictionary dict;
		dict["id"] = evt.id;
		dict["timestamp_msec"] = evt.timestamp_msec;
		dict["event"] = evt.event_name;
		dict["distinct_id"] = evt.distinct_id;
		dict["properties"] = evt.properties;
		result.push_back(dict);
	}

	return result;
}

int AgentAnalytics::get_event_count(const String &p_event_name) {
	MutexLock lock(events_mutex);
	if (p_event_name.is_empty()) {
		return events.size();
	}

	int count = 0;
	for (const AnalyticsEvent &evt : events) {
		if (evt.event_name == p_event_name) {
			count++;
		}
	}
	return count;
}

Dictionary AgentAnalytics::get_event_counts_by_name() {
	Dictionary result;
	MutexLock lock(events_mutex);

	for (const AnalyticsEvent &evt : events) {
		int count = result.has(evt.event_name) ? (int)result[evt.event_name] : 0;
		result[evt.event_name] = count + 1;
	}

	return result;
}

// --- Config ---

void AgentAnalytics::enable_file_sink(const String &p_path) {
	file_sink_path = p_path;
	file_sink_enabled = true;
}

void AgentAnalytics::disable_file_sink() {
	file_sink_enabled = false;
}

void AgentAnalytics::set_remote_endpoint(const String &p_endpoint, const String &p_api_key) {
	remote_endpoint = p_endpoint;
	remote_api_key = p_api_key;
	remote_enabled = true;
}

void AgentAnalytics::disable_remote() {
	remote_enabled = false;
}

void AgentAnalytics::set_super_property(const String &p_key, const Variant &p_value) {
	super_properties[p_key] = p_value;
}

void AgentAnalytics::remove_super_property(const String &p_key) {
	super_properties.erase(p_key);
}

void AgentAnalytics::clear_super_properties() {
	super_properties.clear();
}

void AgentAnalytics::clear() {
	MutexLock lock(events_mutex);
	events.clear();
	next_event_id = 1;
}

// --- Private ---

void AgentAnalytics::_write_event_to_file(const AnalyticsEvent &p_event) {
	Ref<FileAccess> file = FileAccess::open(file_sink_path, FileAccess::READ_WRITE);
	if (file.is_null()) {
		file = FileAccess::open(file_sink_path, FileAccess::WRITE);
	}
	if (file.is_null()) {
		return;
	}

	file->seek_end();

	Dictionary dict;
	dict["id"] = p_event.id;
	dict["timestamp_msec"] = p_event.timestamp_msec;
	dict["event"] = p_event.event_name;
	dict["distinct_id"] = p_event.distinct_id;
	dict["properties"] = p_event.properties;

	file->store_string(JSON::stringify(dict) + "\n");
}

void AgentAnalytics::_send_event_to_remote(const AnalyticsEvent &p_event) {
	// HTTP POST to remote endpoint.
	// For now, this is a stub. Full implementation would use HTTPClient.
	// Events can be batched for efficiency.
}

bool AgentAnalytics::_evaluate_flag_conditions(const FeatureFlag &p_flag, const Dictionary &p_context) {
	// Simple condition evaluation: check if context matches all conditions.
	for (const Variant &key : p_flag.conditions.keys()) {
		if (!p_context.has(key)) {
			return false;
		}
		if (p_context[key] != p_flag.conditions[key]) {
			return false;
		}
	}
	return true;
}

String AgentAnalytics::_generate_session_id() {
	return vformat("session_%d_%d", OS::get_singleton()->get_ticks_msec(), Math::rand() % 10000);
}