package v1

import (
	"bufio"
	"encoding/json"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"strings"
	"time"

	"github.com/gorilla/mux"
	"gopkg.in/yaml.v3"

	"github.com/wild-cloud/wild-central/internal/config"
	"github.com/wild-cloud/wild-central/internal/storage"
)

// DnsmasqStatus returns the status of the dnsmasq service
func (api *API) DnsmasqStatus(w http.ResponseWriter, r *http.Request) {
	status, err := api.dnsmasq.GetStatus()
	if err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to get dnsmasq status: %v", err))
		return
	}

	// Always return 200 OK with status in body - let client handle inactive status
	respondJSON(w, http.StatusOK, status)
}

// DnsmasqGetConfig returns the current dnsmasq configuration
func (api *API) DnsmasqGetConfig(w http.ResponseWriter, r *http.Request) {
	configContent, err := api.dnsmasq.ReadConfig()
	if err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to read dnsmasq config: %v", err))
		return
	}

	respondJSON(w, http.StatusOK, map[string]any{
		"config_file": api.dnsmasq.GetConfigPath(),
		"content":     configContent,
	})
}

// DnsmasqRestart restarts the dnsmasq service
func (api *API) DnsmasqRestart(w http.ResponseWriter, r *http.Request) {
	if err := api.dnsmasq.RestartService(); err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to restart dnsmasq: %v", err))
		return
	}

	// Broadcast SSE event
	api.broadcastDnsmasqEvent("dnsmasq:restart", "dnsmasq service restarted")

	respondJSON(w, http.StatusOK, map[string]string{
		"message": "dnsmasq service restarted successfully",
	})
}

// DnsmasqGenerate generates the dnsmasq configuration from global config.
// Query param ?overwrite=true will write the config and restart the service.
// Instance-specific DNS records are managed via service registration (not here).
func (api *API) DnsmasqGenerate(w http.ResponseWriter, r *http.Request) {
	overwrite := r.URL.Query().Get("overwrite") == "true"

	// Load global config
	globalConfigPath := api.getGlobalConfigPath()
	globalCfg, err := config.LoadGlobalConfig(globalConfigPath)
	if err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to load global config: %v", err))
		return
	}

	// Generate dnsmasq config
	configContent := api.dnsmasq.GenerateMainConfig(globalCfg)

	if overwrite {
		// Check if this is the first time dnsmasq is being started
		status, err := api.dnsmasq.GetStatus()
		isFirstStart := err != nil || status.Status != "active"

		// Update main dnsmasq configuration
		slog.Info("updating dnsmasq main configuration")

		// Write the main config
		tempFile := api.dnsmasq.GetConfigPath() + ".tmp"
		if err := os.WriteFile(tempFile, []byte(configContent), 0644); err != nil {
			respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to write temp config: %v", err))
			return
		}

		// Validate the config
		if err := api.dnsmasq.ValidateConfig(tempFile); err != nil {
			os.Remove(tempFile)
			respondError(w, http.StatusInternalServerError, fmt.Sprintf("Config validation failed: %v", err))
			return
		}

		// Install the new config
		if err := os.Rename(tempFile, api.dnsmasq.GetConfigPath()); err != nil {
			os.Remove(tempFile)
			respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to install config: %v", err))
			return
		}

		// Reload dnsmasq
		if err := api.dnsmasq.ReloadService(); err != nil {
			respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to reload dnsmasq: %v", err))
			return
		}

		// Configure system DNS to use local dnsmasq on first start
		if isFirstStart {
			if err := api.dnsmasq.ConfigureSystemDNS(); err != nil {
				slog.Error("failed to configure system DNS", "error", err)
			}
		}

		// Broadcast SSE event
		api.broadcastDnsmasqEvent("dnsmasq:config", "dnsmasq configuration updated and applied")

		respondJSON(w, http.StatusOK, map[string]any{
			"message": "dnsmasq configuration generated and applied successfully",
			"config":  configContent,
		})
	} else {
		respondJSON(w, http.StatusOK, map[string]any{
			"message": "dnsmasq configuration generated (preview mode)",
			"config":  configContent,
		})
	}
}

// DnsmasqWriteConfig writes custom config content to the dnsmasq config file
func (api *API) DnsmasqWriteConfig(w http.ResponseWriter, r *http.Request) {
	var req struct {
		Content string `json:"content"`
	}

	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		respondError(w, http.StatusBadRequest, fmt.Sprintf("Invalid request: %v", err))
		return
	}

	if req.Content == "" {
		respondError(w, http.StatusBadRequest, "Config content is required")
		return
	}

	// Write the config directly using the dnsmasq config generator's WriteConfig
	configPath := api.dnsmasq.GetConfigPath()
	if err := writeConfigFile(configPath, req.Content); err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to write config: %v", err))
		return
	}

	// Broadcast SSE event
	api.broadcastDnsmasqEvent("dnsmasq:config", "dnsmasq configuration written")

	respondJSON(w, http.StatusOK, map[string]string{
		"message": "dnsmasq configuration written successfully",
	})
}

// writeConfigFile writes content to a file
func writeConfigFile(path, content string) error {
	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
		return fmt.Errorf("writing config: %w", err)
	}
	return nil
}

// updateDnsmasqConfig regenerates the main dnsmasq config from global config and restarts.
// Instance-specific DNS records are managed via service registration (not here).
func (api *API) updateDnsmasqConfig() error {
	globalConfigPath := api.getGlobalConfigPath()
	globalCfg, err := config.LoadGlobalConfig(globalConfigPath)
	if err != nil {
		return fmt.Errorf("loading global config: %w", err)
	}

	// Regenerate and write dnsmasq config with restart (no instance configs)
	return api.dnsmasq.UpdateConfig(globalCfg, nil, true)
}

// getGlobalConfigPath returns the path to the global config file
func (api *API) getGlobalConfigPath() string {
	return api.dataDir + "/config.yaml"
}

// DHCPLease represents an active DHCP lease from the dnsmasq leases file
type DHCPLease struct {
	Expiry   time.Time `json:"expiry"`
	MAC      string    `json:"mac"`
	IP       string    `json:"ip"`
	Hostname string    `json:"hostname"`
}

// DnsmasqDHCPLeases returns active DHCP leases from /var/lib/misc/dnsmasq.leases
func (api *API) DnsmasqDHCPLeases(w http.ResponseWriter, r *http.Request) {
	const leasesFile = "/var/lib/misc/dnsmasq.leases"

	f, err := os.Open(leasesFile)
	if err != nil {
		if os.IsNotExist(err) {
			respondJSON(w, http.StatusOK, map[string]any{"leases": []DHCPLease{}})
			return
		}
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to read leases file: %v", err))
		return
	}
	defer f.Close()

	var leases []DHCPLease
	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if line == "" {
			continue
		}
		// Format: <unix-expiry> <mac> <ip> <hostname> <client-id>
		parts := strings.Fields(line)
		if len(parts) < 4 {
			continue
		}
		var expiry time.Time
		if ts, err := time.Parse("1504605645", parts[0]); err == nil {
			expiry = ts
		}
		hostname := parts[3]
		if hostname == "*" {
			hostname = ""
		}
		leases = append(leases, DHCPLease{
			Expiry:   expiry,
			MAC:      parts[1],
			IP:       parts[2],
			Hostname: hostname,
		})
	}
	if err := scanner.Err(); err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to parse leases file: %v", err))
		return
	}

	respondJSON(w, http.StatusOK, map[string]any{"leases": leases})
}

// DnsmasqDHCPAddStatic adds a static DHCP lease to global config and regenerates dnsmasq
func (api *API) DnsmasqDHCPAddStatic(w http.ResponseWriter, r *http.Request) {
	var req config.DHCPStaticLease
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		respondError(w, http.StatusBadRequest, fmt.Sprintf("Invalid request: %v", err))
		return
	}
	if req.MAC == "" || req.IP == "" {
		respondError(w, http.StatusBadRequest, "mac and ip are required")
		return
	}

	globalConfigPath := api.getGlobalConfigPath()
	if err := api.addDHCPStaticLease(globalConfigPath, req); err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to add static lease: %v", err))
		return
	}

	if err := api.updateDnsmasqConfig(); err != nil {
		slog.Error("dnsmasq regeneration failed after adding static lease", "error", err)
	}

	respondJSON(w, http.StatusOK, map[string]string{"message": "Static lease added successfully"})
}

// DnsmasqDHCPDeleteStatic removes a static DHCP lease from global config and regenerates dnsmasq
func (api *API) DnsmasqDHCPDeleteStatic(w http.ResponseWriter, r *http.Request) {
	mac := mux.Vars(r)["mac"]
	if mac == "" {
		respondError(w, http.StatusBadRequest, "mac address is required")
		return
	}

	globalConfigPath := api.getGlobalConfigPath()
	if err := api.removeDHCPStaticLease(globalConfigPath, mac); err != nil {
		respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to remove static lease: %v", err))
		return
	}

	if err := api.updateDnsmasqConfig(); err != nil {
		slog.Error("dnsmasq regeneration failed after removing static lease", "error", err)
	}

	respondJSON(w, http.StatusOK, map[string]string{"message": "Static lease removed successfully"})
}

// addDHCPStaticLease adds or replaces a static lease entry in the global config file
func (api *API) addDHCPStaticLease(configPath string, lease config.DHCPStaticLease) error {
	data, err := os.ReadFile(configPath)
	if err != nil {
		return fmt.Errorf("reading config: %w", err)
	}

	var cfg map[string]any
	if err := yaml.Unmarshal(data, &cfg); err != nil {
		return fmt.Errorf("parsing config: %w", err)
	}
	if cfg == nil {
		cfg = make(map[string]any)
	}

	// Navigate/create the path cloud.dnsmasq.dhcp.staticLeases
	cloud := getOrCreateMap(cfg, "cloud")
	dnsmasqMap := getOrCreateMap(cloud, "dnsmasq")
	dhcpMap := getOrCreateMap(dnsmasqMap, "dhcp")

	leases, _ := dhcpMap["staticLeases"].([]any)

	// Replace existing entry with same MAC, or append
	newEntry := map[string]any{"mac": lease.MAC, "ip": lease.IP}
	if lease.Hostname != "" {
		newEntry["hostname"] = lease.Hostname
	}
	replaced := false
	for i, l := range leases {
		if m, ok := l.(map[string]any); ok {
			if m["mac"] == lease.MAC {
				leases[i] = newEntry
				replaced = true
				break
			}
		}
	}
	if !replaced {
		leases = append(leases, newEntry)
	}
	dhcpMap["staticLeases"] = leases

	out, err := yaml.Marshal(cfg)
	if err != nil {
		return fmt.Errorf("marshaling config: %w", err)
	}

	lockPath := configPath + ".lock"
	return storage.WithLock(lockPath, func() error {
		return storage.WriteFile(configPath, out, 0644)
	})
}

// removeDHCPStaticLease removes a static lease entry by MAC from the global config file
func (api *API) removeDHCPStaticLease(configPath string, mac string) error {
	data, err := os.ReadFile(configPath)
	if err != nil {
		return fmt.Errorf("reading config: %w", err)
	}

	var cfg map[string]any
	if err := yaml.Unmarshal(data, &cfg); err != nil {
		return fmt.Errorf("parsing config: %w", err)
	}

	cloud, _ := cfg["cloud"].(map[string]any)
	if cloud == nil {
		return nil
	}
	dnsmasqMap, _ := cloud["dnsmasq"].(map[string]any)
	if dnsmasqMap == nil {
		return nil
	}
	dhcpMap, _ := dnsmasqMap["dhcp"].(map[string]any)
	if dhcpMap == nil {
		return nil
	}

	leases, _ := dhcpMap["staticLeases"].([]any)
	var filtered []any
	for _, l := range leases {
		if m, ok := l.(map[string]any); ok {
			if m["mac"] != mac {
				filtered = append(filtered, l)
			}
		}
	}
	dhcpMap["staticLeases"] = filtered

	out, err := yaml.Marshal(cfg)
	if err != nil {
		return fmt.Errorf("marshaling config: %w", err)
	}

	lockPath := configPath + ".lock"
	return storage.WithLock(lockPath, func() error {
		return storage.WriteFile(configPath, out, 0644)
	})
}

// getOrCreateMap returns the map at key in parent, creating it if absent
func getOrCreateMap(parent map[string]any, key string) map[string]any {
	if v, ok := parent[key].(map[string]any); ok {
		return v
	}
	m := make(map[string]any)
	parent[key] = m
	return m
}