package database

import (
	"context"
	"fmt"
	"net"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"

	"github.com/rqlite/gorqlite"
	"go.uber.org/zap"

	"git.debros.io/DeBros/network/pkg/config"
)

// RQLiteManager manages an RQLite node instance
type RQLiteManager struct {
	config     *config.DatabaseConfig
	dataDir    string
	logger     *zap.Logger
	cmd        *exec.Cmd
	connection *gorqlite.Connection
}

// NewRQLiteManager creates a new RQLite manager
func NewRQLiteManager(cfg *config.DatabaseConfig, dataDir string, logger *zap.Logger) *RQLiteManager {
	return &RQLiteManager{
		config:  cfg,
		dataDir: dataDir,
		logger:  logger,
	}
}

// Start starts the RQLite node
func (r *RQLiteManager) Start(ctx context.Context) error {
	// Create data directory
	rqliteDataDir := filepath.Join(r.dataDir, "rqlite")
	if err := os.MkdirAll(rqliteDataDir, 0755); err != nil {
		return fmt.Errorf("failed to create RQLite data directory: %w", err)
	}

	// Determine advertise host based on configuration
	advertiseHost := "127.0.0.1" // default
	mode := strings.ToLower(r.config.AdvertiseMode)
	switch mode {
	case "localhost":
		advertiseHost = "127.0.0.1"
		r.logger.Info("Using localhost for RQLite advertising (dev mode)")
	case "ip":
		if ip, err := r.getExternalIP(); err == nil && ip != "" {
			advertiseHost = ip
			r.logger.Info("Using external IP for RQLite advertising (forced)", zap.String("ip", ip))
		} else {
			r.logger.Warn("Failed to get external IP, falling back to localhost", zap.Error(err))
		}
	default: // auto
		if ip, err := r.getExternalIP(); err == nil && ip != "" {
			advertiseHost = ip
			r.logger.Info("Using external IP for RQLite advertising (auto)", zap.String("ip", ip))
		} else {
			r.logger.Info("No external IP found, using localhost for RQLite advertising (auto)")
		}
	}

	// Build RQLite command
	args := []string{
		"-http-addr", fmt.Sprintf("0.0.0.0:%d", r.config.RQLitePort),
		"-raft-addr", fmt.Sprintf("0.0.0.0:%d", r.config.RQLiteRaftPort),
		// Auth disabled for testing
	}

	// Always set advertised addresses explicitly to avoid 0.0.0.0 announcements
	args = append(args, "-http-adv-addr", fmt.Sprintf("%s:%d", advertiseHost, r.config.RQLitePort))
	args = append(args, "-raft-adv-addr", fmt.Sprintf("%s:%d", advertiseHost, r.config.RQLiteRaftPort))

	// Add join address if specified (for non-bootstrap or secondary bootstrap nodes)
	if r.config.RQLiteJoinAddress != "" {
		r.logger.Info("Joining RQLite cluster", zap.String("join_address", r.config.RQLiteJoinAddress))

		// Normalize join address to host:port for rqlited -join
		joinArg := r.config.RQLiteJoinAddress
		if strings.HasPrefix(joinArg, "http://") {
			joinArg = strings.TrimPrefix(joinArg, "http://")
		} else if strings.HasPrefix(joinArg, "https://") {
			joinArg = strings.TrimPrefix(joinArg, "https://")
		}

		// Test connectivity (HTTP status) on the leader's HTTP port derived from join host
		if err := r.testJoinAddress(joinArg); err != nil {
			r.logger.Warn("Join target connectivity test failed, but will still attempt to join",
				zap.String("join_address", r.config.RQLiteJoinAddress),
				zap.Error(err))
		} else {
			r.logger.Info("Join target is reachable, proceeding with cluster join")
		}

		// Always add the join parameter in host:port form - let rqlited handle the rest
		args = append(args, "-join", joinArg)
	} else {
		r.logger.Info("No join address specified - starting as new cluster")
	}

	// Add data directory as positional argument
	args = append(args, rqliteDataDir)

	r.logger.Info("Starting RQLite node",
		zap.String("data_dir", rqliteDataDir),
		zap.Int("http_port", r.config.RQLitePort),
		zap.Int("raft_port", r.config.RQLiteRaftPort),
		zap.String("join_address", r.config.RQLiteJoinAddress),
		zap.String("advertise_host", advertiseHost),
		zap.Strings("full_args", args),
	)

	// Start RQLite process
	r.cmd = exec.CommandContext(ctx, "rqlited", args...)
	r.cmd.Stdout = os.Stdout
	r.cmd.Stderr = os.Stderr

	if err := r.cmd.Start(); err != nil {
		return fmt.Errorf("failed to start RQLite: %w", err)
	}

	// Wait for RQLite to be ready
	if err := r.waitForReady(ctx); err != nil {
		r.cmd.Process.Kill()
		return fmt.Errorf("RQLite failed to become ready: %w", err)
	}

	// Create connection
	conn, err := gorqlite.Open(fmt.Sprintf("http://localhost:%d", r.config.RQLitePort))
	if err != nil {
		r.cmd.Process.Kill()
		return fmt.Errorf("failed to connect to RQLite: %w", err)
	}
	r.connection = conn

	// Wait for RQLite to establish leadership (for bootstrap nodes)
	if r.config.RQLiteJoinAddress == "" {
		if err := r.waitForLeadership(ctx); err != nil {
			r.cmd.Process.Kill()
			return fmt.Errorf("RQLite failed to establish leadership: %w", err)
		}
	}

	r.logger.Info("RQLite node started successfully")
	return nil
}

// waitForReady waits for RQLite to be ready to accept connections
func (r *RQLiteManager) waitForReady(ctx context.Context) error {
	url := fmt.Sprintf("http://localhost:%d/status", r.config.RQLitePort)
	client := &http.Client{Timeout: 2 * time.Second}

	for i := 0; i < 30; i++ {
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
		}

		resp, err := client.Get(url)
		if err == nil {
			resp.Body.Close()
			if resp.StatusCode == http.StatusOK {
				return nil
			}
		}

		time.Sleep(1 * time.Second)
	}

	return fmt.Errorf("RQLite did not become ready within timeout")
}

// waitForLeadership waits for RQLite to establish leadership (for bootstrap nodes)
func (r *RQLiteManager) waitForLeadership(ctx context.Context) error {
	r.logger.Info("Waiting for RQLite to establish leadership...")

	for i := 0; i < 30; i++ {
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
		}

		// Try a simple query to check if leadership is established
		if r.connection != nil {
			_, err := r.connection.QueryOne("SELECT 1")
			if err == nil {
				r.logger.Info("RQLite leadership established")
				return nil
			}
			r.logger.Debug("Waiting for leadership", zap.Error(err))
		}

		time.Sleep(1 * time.Second)
	}

	return fmt.Errorf("RQLite failed to establish leadership within timeout")
}

// GetConnection returns the RQLite connection
func (r *RQLiteManager) GetConnection() *gorqlite.Connection {
	return r.connection
}

// Stop stops the RQLite node
func (r *RQLiteManager) Stop() error {
	if r.connection != nil {
		r.connection.Close()
	}

	if r.cmd != nil && r.cmd.Process != nil {
		r.logger.Info("Stopping RQLite node")
		return r.cmd.Process.Kill()
	}

	return nil
}

// getExternalIP attempts to get the external IP address of this machine
func (r *RQLiteManager) getExternalIP() (string, error) {
	// Method 1: Try using `ip route get` to find the IP used to reach the internet
	if output, err := exec.Command("ip", "route", "get", "8.8.8.8").Output(); err == nil {
		lines := strings.Split(string(output), "\n")
		for _, line := range lines {
			if strings.Contains(line, "src") {
				parts := strings.Fields(line)
				for i, part := range parts {
					if part == "src" && i+1 < len(parts) {
						ip := parts[i+1]
						if net.ParseIP(ip) != nil {
							r.logger.Debug("Found external IP via ip route", zap.String("ip", ip))
							return ip, nil
						}
					}
				}
			}
		}
	}

	// Method 2: Get all network interfaces and find non-localhost, non-private IPs
	interfaces, err := net.Interfaces()
	if err != nil {
		return "", err
	}

	for _, iface := range interfaces {
		if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
			continue
		}

		addrs, err := iface.Addrs()
		if err != nil {
			continue
		}

		for _, addr := range addrs {
			var ip net.IP
			switch v := addr.(type) {
			case *net.IPNet:
				ip = v.IP
			case *net.IPAddr:
				ip = v.IP
			}

			if ip == nil || ip.IsLoopback() {
				continue
			}

			// Prefer public IPs over private IPs
			if ip.To4() != nil && !ip.IsPrivate() {
				r.logger.Debug("Found public IP", zap.String("ip", ip.String()))
				return ip.String(), nil
			}
		}
	}

	// Method 3: Fall back to private IPs if no public IP found
	for _, iface := range interfaces {
		if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
			continue
		}

		addrs, err := iface.Addrs()
		if err != nil {
			continue
		}

		for _, addr := range addrs {
			var ip net.IP
			switch v := addr.(type) {
			case *net.IPNet:
				ip = v.IP
			case *net.IPAddr:
				ip = v.IP
			}

			if ip == nil || ip.IsLoopback() {
				continue
			}

			// Use any IPv4 address
			if ip.To4() != nil {
				r.logger.Debug("Found private IP", zap.String("ip", ip.String()))
				return ip.String(), nil
			}
		}
	}

	return "", fmt.Errorf("no suitable IP address found")
}

// testJoinAddress tests if a join address is reachable
func (r *RQLiteManager) testJoinAddress(joinAddress string) error {
	// Determine the HTTP status URL to probe.
	// If joinAddress contains a scheme, use it directly. Otherwise treat joinAddress
	// as host:port (Raft) and probe the standard HTTP API port 5001 on that host.
	client := &http.Client{Timeout: 5 * time.Second}

	var statusURL string
	if strings.HasPrefix(joinAddress, "http://") || strings.HasPrefix(joinAddress, "https://") {
		statusURL = strings.TrimRight(joinAddress, "/") + "/status"
	} else {
		// Extract host from host:port
		host := joinAddress
		if idx := strings.Index(joinAddress, ":"); idx != -1 {
			host = joinAddress[:idx]
		}
		statusURL = fmt.Sprintf("http://%s:%d/status", host, 5001)
	}

	r.logger.Debug("Testing join target via HTTP", zap.String("url", statusURL))
	resp, err := client.Get(statusURL)
	if err != nil {
		return fmt.Errorf("failed to connect to leader HTTP at %s: %w", statusURL, err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("leader HTTP at %s returned status %d", statusURL, resp.StatusCode)
	}

	r.logger.Info("Leader HTTP reachable", zap.String("status_url", statusURL))
	return nil
}