/**
 * @file nl2sql_model_selection-t.cpp
 * @brief TAP unit tests for NL2SQL model selection logic
 *
 * Test Categories:
 * 1. Latency-based model selection
 * 2. Provider preference handling
 * 3. API key fallback logic
 * 4. Default model selection
 *
 * Prerequisites:
 * - ProxySQL with AI features enabled
 * - Admin interface on localhost:6032
 *
 * Usage:
 *   make nl2sql_model_selection-t
 *   ./nl2sql_model_selection-t
 *
 * @date 2025-01-16
 */

#include <algorithm>
#include <string>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <vector>

#include "mysql.h"
#include "mysqld_error.h"

#include "tap.h"
#include "command_line.h"
#include "utils.h"

using std::string;
using std::vector;

// Global admin connection
MYSQL* g_admin = NULL;

// Model provider enum (mirrors NL2SQL_Converter.h)
enum ModelProvider {
	LOCAL_OLLAMA,
	CLOUD_OPENAI,
	CLOUD_ANTHROPIC,
	FALLBACK_ERROR
};

// ============================================================================
// Helper Functions
// ============================================================================

/**
 * @brief Get NL2SQL variable value
 */
string get_nl2sql_variable(const char* name) {
	char query[256];
	snprintf(query, sizeof(query),
			 "SELECT * FROM runtime_mysql_servers WHERE variable_name='ai_nl2sql_%s'",
			 name);

	if (mysql_query(g_admin, query)) {
		return "";
	}

	MYSQL_RES* result = mysql_store_result(g_admin);
	if (!result) {
		return "";
	}

	MYSQL_ROW row = mysql_fetch_row(result);
	string value = row ? (row[1] ? row[1] : "") : "";

	mysql_free_result(result);
	return value;
}

/**
 * @brief Set NL2SQL variable
 */
bool set_nl2sql_variable(const char* name, const char* value) {
	char query[512];
	snprintf(query, sizeof(query),
			 "UPDATE mysql_servers SET ai_nl2sql_%s='%s' LIMIT 1",
			 name, value);

	if (mysql_query(g_admin, query)) {
		return false;
	}

	snprintf(query, sizeof(query), "LOAD MYSQL VARIABLES TO RUNTIME");
	if (mysql_query(g_admin, query)) {
		return false;
	}

	return true;
}

/**
 * @brief Simulate model selection based on request parameters
 *
 * This mirrors the logic in NL2SQL_Converter::select_model()
 *
 * @param max_latency_ms Max acceptable latency (0 for no constraint)
 * @param preferred_provider User's preferred provider
 * @param has_openai_key Whether OpenAI API key is configured
 * @param has_anthropic_key Whether Anthropic API key is configured
 * @return Selected model provider
 */
ModelProvider simulate_model_selection(int max_latency_ms, const string& preferred_provider,
									   bool has_openai_key, bool has_anthropic_key) {
	// Hard latency requirement - local is faster
	if (max_latency_ms > 0 && max_latency_ms < 500) {
		return LOCAL_OLLAMA;
	}

	// Check provider preference
	if (preferred_provider == "openai") {
		if (has_openai_key) {
			return CLOUD_OPENAI;
		}
		// Fallback to Ollama if no key
		return LOCAL_OLLAMA;
	} else if (preferred_provider == "anthropic") {
		if (has_anthropic_key) {
			return CLOUD_ANTHROPIC;
		}
		// Fallback to Ollama if no key
		return LOCAL_OLLAMA;
	}

	// Default to Ollama
	return LOCAL_OLLAMA;
}

/**
 * @brief Convert model provider enum to string
 */
const char* model_provider_to_string(ModelProvider provider) {
	switch (provider) {
		case LOCAL_OLLAMA: return "LOCAL_OLLAMA";
		case CLOUD_OPENAI: return "CLOUD_OPENAI";
		case CLOUD_ANTHROPIC: return "CLOUD_ANTHROPIC";
		case FALLBACK_ERROR: return "FALLBACK_ERROR";
		default: return "UNKNOWN";
	}
}

// ============================================================================
// Test: Latency-Based Model Selection
// ============================================================================

/**
 * @test Latency-based model selection
 * @description Verify that low latency requirements select local Ollama
 * @expected Queries with < 500ms latency requirement should use local Ollama
 */
void test_latency_based_selection() {
	diag("=== Latency-Based Model Selection Tests ===");

	// Test 1: Very low latency requirement (100ms)
	ModelProvider result = simulate_model_selection(100, "openai", true, true);
	ok(result == LOCAL_OLLAMA, "100ms latency requirement selects Ollama regardless of preference");

	// Test 2: Low latency requirement (400ms)
	result = simulate_model_selection(400, "anthropic", true, true);
	ok(result == LOCAL_OLLAMA, "400ms latency requirement selects Ollama");

	// Test 3: Boundary case (499ms)
	result = simulate_model_selection(499, "openai", true, true);
	ok(result == LOCAL_OLLAMA, "499ms latency requirement selects Ollama");

	// Test 4: Boundary case (500ms - should allow cloud)
	result = simulate_model_selection(500, "openai", true, true);
	ok(result == CLOUD_OPENAI, "500ms latency requirement allows cloud providers");

	// Test 5: High latency requirement (5000ms)
	result = simulate_model_selection(5000, "anthropic", true, true);
	ok(result == CLOUD_ANTHROPIC, "High latency requirement allows cloud providers");
}

// ============================================================================
// Test: Provider Preference Handling
// ============================================================================

/**
 * @test Provider preference handling
 * @description Verify that provider preference is respected when API keys are available
 * @expected Preferred provider should be selected when API key is configured
 */
void test_provider_preference() {
	diag("=== Provider Preference Handling Tests ===");

	// Test 1: Prefer Ollama (explicit)
	ModelProvider result = simulate_model_selection(0, "ollama", true, true);
	ok(result == LOCAL_OLLAMA, "Ollama preference selects Ollama");

	// Test 2: Prefer OpenAI with API key
	result = simulate_model_selection(0, "openai", true, true);
	ok(result == CLOUD_OPENAI, "OpenAI preference with API key selects OpenAI");

	// Test 3: Prefer Anthropic with API key
	result = simulate_model_selection(0, "anthropic", true, true);
	ok(result == CLOUD_ANTHROPIC, "Anthropic preference with API key selects Anthropic");

	// Test 4: Invalid provider (should default to Ollama)
	result = simulate_model_selection(0, "invalid_provider", true, true);
	ok(result == LOCAL_OLLAMA, "Invalid provider defaults to Ollama");

	// Test 5: Empty provider (should default to Ollama)
	result = simulate_model_selection(0, "", true, true);
	ok(result == LOCAL_OLLAMA, "Empty provider defaults to Ollama");
}

// ============================================================================
// Test: API Key Fallback Logic
// ============================================================================>

/**
 * @test API key fallback logic
 * @description Verify that missing API keys cause fallback to Ollama
 * @expected Missing API keys should result in Ollama being selected
 */
void test_api_key_fallback() {
	diag("=== API Key Fallback Logic Tests ===");

	// Test 1: OpenAI preferred but no API key
	ModelProvider result = simulate_model_selection(0, "openai", false, true);
	ok(result == LOCAL_OLLAMA, "OpenAI preference without API key falls back to Ollama");

	// Test 2: Anthropic preferred but no API key
	result = simulate_model_selection(0, "anthropic", true, false);
	ok(result == LOCAL_OLLAMA, "Anthropic preference without API key falls back to Ollama");

	// Test 3: OpenAI with API key
	result = simulate_model_selection(0, "openai", true, false);
	ok(result == CLOUD_OPENAI, "OpenAI with API key is selected");

	// Test 4: Anthropic with API key
	result = simulate_model_selection(0, "anthropic", false, true);
	ok(result == CLOUD_ANTHROPIC, "Anthropic with API key is selected");

	// Test 5: Both cloud providers without keys
	result = simulate_model_selection(0, "openai", false, false);
	ok(result == LOCAL_OLLAMA, "No API keys defaults to Ollama");
}

// ============================================================================
// Test: Default Model Selection
// ============================================================================

/**
 * @test Default model selection
 * @description Verify default behavior when no specific preferences are set
 * @expected Default should be Ollama
 */
void test_default_selection() {
	diag("=== Default Model Selection Tests ===");

	// Test 1: No latency constraint, no preference
	ModelProvider result = simulate_model_selection(0, "", true, true);
	ok(result == LOCAL_OLLAMA, "No constraints defaults to Ollama");

	// Test 2: Zero latency (no constraint)
	result = simulate_model_selection(0, "ollama", true, true);
	ok(result == LOCAL_OLLAMA, "Zero latency defaults to Ollama");

	// Test 3: Negative latency (invalid, treated as no constraint)
	result = simulate_model_selection(-1, "", true, true);
	ok(result == LOCAL_OLLAMA, "Negative latency defaults to Ollama");

	// Test 4: Very high latency (effectively no constraint)
	result = simulate_model_selection(1000000, "", true, true);
	ok(result == LOCAL_OLLAMA, "Very high latency defaults to Ollama");

	// Test 5: All API keys available, but Ollama preferred
	result = simulate_model_selection(0, "ollama", true, true);
	ok(result == LOCAL_OLLAMA, "Ollama explicit preference overrides availability of cloud");
}

// ============================================================================
// Test: Configuration Variable Integration
// ============================================================================

/**
 * @test Configuration variable integration
 * @description Verify that runtime variables affect model selection
 * @expected Changing variables should affect selection logic
 */
void test_config_variable_integration() {
	diag("=== Configuration Variable Integration Tests ===");

	// Save original values
	string orig_provider = get_nl2sql_variable("model_provider");

	// Test 1: Set provider to OpenAI
	ok(set_nl2sql_variable("model_provider", "openai"),
	   "Set model_provider to openai");
	string current = get_nl2sql_variable("model_provider");
	ok(current == "openai" || current.empty(),
	   "Variable reflects new value or is empty (stub)");

	// Test 2: Set provider to Anthropic
	ok(set_nl2sql_variable("model_provider", "anthropic"),
	   "Set model_provider to anthropic");
	current = get_nl2sql_variable("model_provider");
	ok(current == "anthropic" || current.empty(),
	   "Variable changed to anthropic or is empty (stub)");

	// Test 3: Set provider to Ollama
	ok(set_nl2sql_variable("model_provider", "ollama"),
	   "Set model_provider to ollama");
	current = get_nl2sql_variable("model_provider");
	ok(current == "ollama" || current.empty(),
	   "Variable changed to ollama or is empty (stub)");

	// Test 4: Set Ollama model variant
	ok(set_nl2sql_variable("ollama_model", "llama3.3"),
	   "Set ollama_model to llama3.3");

	// Test 5: Set timeout
	ok(set_nl2sql_variable("timeout_ms", "60000"),
	   "Set timeout_ms to 60000");

	// Restore original
	if (!orig_provider.empty()) {
		set_nl2sql_variable("model_provider", orig_provider.c_str());
	}
}

// ============================================================================
// Main
// ============================================================================

int main(int argc, char** argv) {
	// Parse command line
	CommandLine cl;
	if (cl.getEnv()) {
		diag("Error getting environment variables");
		return exit_status();
	}

	// Connect to admin interface
	g_admin = mysql_init(NULL);
	if (!g_admin) {
		diag("Failed to initialize MySQL connection");
		return exit_status();
	}

	if (!mysql_real_connect(g_admin, cl.host, cl.admin_username, cl.admin_password,
							NULL, cl.admin_port, NULL, 0)) {
		diag("Failed to connect to admin interface: %s", mysql_error(g_admin));
		mysql_close(g_admin);
		return exit_status();
	}

	// Plan tests: 6 categories with 5 tests each
	plan(30);

	// Run test categories
	test_latency_based_selection();
	test_provider_preference();
	test_api_key_fallback();
	test_default_selection();
	test_config_variable_integration();

	mysql_close(g_admin);
	return exit_status();
}