package client

import (
	"bufio"
	"fmt"
	"net"
	"strings"
	"sync"
	"time"

	"github.com/rs/zerolog"
)

// AsteriskServer defines an Asterisk AMI endpoint
type AsteriskServer struct {
	Host    string `yaml:"host"`
	AMIPort int    `yaml:"amiPort"`
}

// AsteriskClient manages AMI connections to Asterisk servers
type AsteriskClient struct {
	servers []AsteriskServer
	user    string
	secret  string
	logger  zerolog.Logger
}

// NewAsteriskClient creates a new Asterisk AMI client
func NewAsteriskClient(servers []AsteriskServer, user, secret string, logger zerolog.Logger) *AsteriskClient {
	return &AsteriskClient{
		servers: servers,
		user:    user,
		secret:  secret,
		logger:  logger.With().Str("client", "asterisk").Logger(),
	}
}

// ReloadPJSIP sends a PJSIP reload command to all Asterisk servers
func (c *AsteriskClient) ReloadPJSIP() []ServerResult {
	return c.runOnAll("pjsip reload")
}

// ReloadDialplan sends a dialplan reload to all Asterisk servers
func (c *AsteriskClient) ReloadDialplan() []ServerResult {
	return c.runOnAll("dialplan reload")
}

// ReloadAll reloads both PJSIP and dialplan on all servers
func (c *AsteriskClient) ReloadAll() []ServerResult {
	results := c.runOnAll("core reload")
	return results
}

// GetChannelCount returns active channel count from each server
func (c *AsteriskClient) GetChannelCount() []ServerResult {
	return c.runOnAll("core show channels count")
}

// GetUptime returns uptime from each server
func (c *AsteriskClient) GetUptime() []ServerResult {
	return c.runOnAll("core show uptime")
}

// ServerResult holds the result from an AMI command on a single server
type ServerResult struct {
	Host    string `json:"host"`
	Success bool   `json:"success"`
	Output  string `json:"output"`
	Error   string `json:"error,omitempty"`
}

// runOnAll executes an AMI command on all Asterisk servers in parallel
func (c *AsteriskClient) runOnAll(command string) []ServerResult {
	var wg sync.WaitGroup
	results := make([]ServerResult, len(c.servers))

	for i, srv := range c.servers {
		wg.Add(1)
		go func(idx int, server AsteriskServer) {
			defer wg.Done()
			results[idx] = c.execAMI(server, command)
		}(i, srv)
	}

	wg.Wait()
	return results
}

// execAMI connects to a single Asterisk AMI server and executes a command
func (c *AsteriskClient) execAMI(server AsteriskServer, command string) ServerResult {
	addr := fmt.Sprintf("%s:%d", server.Host, server.AMIPort)
	result := ServerResult{Host: server.Host}

	conn, err := net.DialTimeout("tcp", addr, 5*time.Second)
	if err != nil {
		result.Error = fmt.Sprintf("connection failed: %v", err)
		c.logger.Warn().Str("host", server.Host).Err(err).Msg("AMI connection failed")
		return result
	}
	defer conn.Close()
	conn.SetDeadline(time.Now().Add(10 * time.Second))

	reader := bufio.NewReader(conn)

	// Read AMI banner
	banner, err := reader.ReadString('\n')
	if err != nil {
		result.Error = fmt.Sprintf("failed to read banner: %v", err)
		return result
	}
	if !strings.HasPrefix(banner, "Asterisk Call Manager") {
		result.Error = fmt.Sprintf("unexpected banner: %s", strings.TrimSpace(banner))
		return result
	}

	// Login
	loginMsg := fmt.Sprintf("Action: Login\r\nUsername: %s\r\nSecret: %s\r\n\r\n",
		c.user, c.secret)
	if _, err := conn.Write([]byte(loginMsg)); err != nil {
		result.Error = fmt.Sprintf("login write failed: %v", err)
		return result
	}

	// Read login response
	loginResp, err := readAMIResponse(reader)
	if err != nil {
		result.Error = fmt.Sprintf("login response failed: %v", err)
		return result
	}
	if !strings.Contains(loginResp, "Success") {
		result.Error = fmt.Sprintf("login failed: %s", loginResp)
		return result
	}

	// Execute command
	cmdMsg := fmt.Sprintf("Action: Command\r\nCommand: %s\r\n\r\n", command)
	if _, err := conn.Write([]byte(cmdMsg)); err != nil {
		result.Error = fmt.Sprintf("command write failed: %v", err)
		return result
	}

	// Read command response
	cmdResp, err := readAMIResponse(reader)
	if err != nil {
		result.Error = fmt.Sprintf("command response failed: %v", err)
		return result
	}

	// Logoff
	conn.Write([]byte("Action: Logoff\r\n\r\n"))

	result.Success = true
	result.Output = cmdResp
	c.logger.Debug().Str("host", server.Host).Str("command", command).Msg("AMI command executed")
	return result
}

// readAMIResponse reads a complete AMI response (terminated by blank line)
func readAMIResponse(reader *bufio.Reader) (string, error) {
	var lines []string
	for {
		line, err := reader.ReadString('\n')
		if err != nil {
			return strings.Join(lines, "\n"), err
		}
		trimmed := strings.TrimSpace(line)
		if trimmed == "" {
			break
		}
		lines = append(lines, trimmed)
	}
	return strings.Join(lines, "\n"), nil
}

// Health checks connectivity to all Asterisk servers
func (c *AsteriskClient) Health() error {
	for _, srv := range c.servers {
		addr := fmt.Sprintf("%s:%d", srv.Host, srv.AMIPort)
		conn, err := net.DialTimeout("tcp", addr, 3*time.Second)
		if err != nil {
			return fmt.Errorf("asterisk %s unreachable: %w", srv.Host, err)
		}
		conn.Close()
	}
	return nil
}

// Servers returns the configured server list
func (c *AsteriskClient) Servers() []AsteriskServer {
	return c.servers
}