package config

import (
	"context"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"sync"
	"syscall"
	"time"
)

// RuntimeConfig provides dynamic configuration with assignment override support
type RuntimeConfig struct {
	mu   sync.RWMutex
	base *Config // Base configuration from environment
	over *Config // Override configuration from assignment
}

// AssignmentConfig represents configuration received from WHOOSH assignment
type AssignmentConfig struct {
	Role                  string            `json:"role,omitempty"`
	Model                 string            `json:"model,omitempty"`
	PromptUCXL           string            `json:"prompt_ucxl,omitempty"`
	Specialization       string            `json:"specialization,omitempty"`
	Capabilities         []string          `json:"capabilities,omitempty"`
	Environment          map[string]string `json:"environment,omitempty"`
	BootstrapPeers       []string          `json:"bootstrap_peers,omitempty"`
	JoinStaggerMS        int               `json:"join_stagger_ms,omitempty"`
	DialsPerSecond       int               `json:"dials_per_second,omitempty"`
	MaxConcurrentDHT     int               `json:"max_concurrent_dht,omitempty"`
	AssignmentID         string            `json:"assignment_id,omitempty"`
	ConfigEpoch          int64             `json:"config_epoch,omitempty"`
}

// NewRuntimeConfig creates a new runtime configuration manager
func NewRuntimeConfig(baseConfig *Config) *RuntimeConfig {
	return &RuntimeConfig{
		base: baseConfig,
		over: &Config{}, // Empty override initially
	}
}

// Get retrieves a configuration value with override precedence
func (rc *RuntimeConfig) Get(key string) interface{} {
	rc.mu.RLock()
	defer rc.mu.RUnlock()

	// Check override first, then base
	if value := rc.getFromConfig(rc.over, key); value != nil {
		return value
	}
	return rc.getFromConfig(rc.base, key)
}

// getFromConfig extracts a value from a config struct by key
func (rc *RuntimeConfig) getFromConfig(cfg *Config, key string) interface{} {
	if cfg == nil {
		return nil
	}

	switch key {
	case "agent.role":
		if cfg.Agent.Role != "" {
			return cfg.Agent.Role
		}
	case "agent.specialization":
		if cfg.Agent.Specialization != "" {
			return cfg.Agent.Specialization
		}
	case "agent.capabilities":
		if len(cfg.Agent.Capabilities) > 0 {
			return cfg.Agent.Capabilities
		}
	case "agent.models":
		if len(cfg.Agent.Models) > 0 {
			return cfg.Agent.Models
		}
	case "agent.default_reasoning_model":
		if cfg.Agent.DefaultReasoningModel != "" {
			return cfg.Agent.DefaultReasoningModel
		}
	case "v2.dht.bootstrap_peers":
		if len(cfg.V2.DHT.BootstrapPeers) > 0 {
			return cfg.V2.DHT.BootstrapPeers
		}
	}

	return nil
}

// GetString retrieves a string configuration value
func (rc *RuntimeConfig) GetString(key string) string {
	if value := rc.Get(key); value != nil {
		if str, ok := value.(string); ok {
			return str
		}
	}
	return ""
}

// GetStringSlice retrieves a string slice configuration value
func (rc *RuntimeConfig) GetStringSlice(key string) []string {
	if value := rc.Get(key); value != nil {
		if slice, ok := value.([]string); ok {
			return slice
		}
	}
	return nil
}

// GetInt retrieves an integer configuration value
func (rc *RuntimeConfig) GetInt(key string) int {
	if value := rc.Get(key); value != nil {
		if i, ok := value.(int); ok {
			return i
		}
	}
	return 0
}

// LoadAssignment loads configuration from WHOOSH assignment endpoint
func (rc *RuntimeConfig) LoadAssignment(ctx context.Context) error {
	assignURL := os.Getenv("ASSIGN_URL")
	if assignURL == "" {
		return nil // No assignment URL configured
	}

	// Build assignment request URL with task identity
	params := url.Values{}
	if taskSlot := os.Getenv("TASK_SLOT"); taskSlot != "" {
		params.Set("slot", taskSlot)
	}
	if taskID := os.Getenv("TASK_ID"); taskID != "" {
		params.Set("task", taskID)
	}
	if clusterID := os.Getenv("CHORUS_CLUSTER_ID"); clusterID != "" {
		params.Set("cluster", clusterID)
	}

	fullURL := assignURL
	if len(params) > 0 {
		fullURL += "?" + params.Encode()
	}

	// Fetch assignment with timeout
	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
	defer cancel()

	req, err := http.NewRequestWithContext(ctx, "GET", fullURL, nil)
	if err != nil {
		return fmt.Errorf("failed to create assignment request: %w", err)
	}

	client := &http.Client{Timeout: 10 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("assignment request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("assignment request failed with status %d", resp.StatusCode)
	}

	// Parse assignment response
	var assignment AssignmentConfig
	if err := json.NewDecoder(resp.Body).Decode(&assignment); err != nil {
		return fmt.Errorf("failed to decode assignment response: %w", err)
	}

	// Apply assignment to override config
	if err := rc.applyAssignment(&assignment); err != nil {
		return fmt.Errorf("failed to apply assignment: %w", err)
	}

	fmt.Printf("📥 Loaded assignment: role=%s, model=%s, epoch=%d\n",
		assignment.Role, assignment.Model, assignment.ConfigEpoch)

	return nil
}

// LoadAssignmentFromFile loads configuration from a file (for config objects)
func (rc *RuntimeConfig) LoadAssignmentFromFile(filePath string) error {
	if filePath == "" {
		return nil // No file configured
	}

	data, err := ioutil.ReadFile(filePath)
	if err != nil {
		return fmt.Errorf("failed to read assignment file %s: %w", filePath, err)
	}

	var assignment AssignmentConfig
	if err := json.Unmarshal(data, &assignment); err != nil {
		return fmt.Errorf("failed to parse assignment file: %w", err)
	}

	if err := rc.applyAssignment(&assignment); err != nil {
		return fmt.Errorf("failed to apply file assignment: %w", err)
	}

	fmt.Printf("📁 Loaded assignment from file: role=%s, model=%s\n",
		assignment.Role, assignment.Model)

	return nil
}

// applyAssignment applies an assignment to the override configuration
func (rc *RuntimeConfig) applyAssignment(assignment *AssignmentConfig) error {
	rc.mu.Lock()
	defer rc.mu.Unlock()

	// Create new override config
	override := &Config{
		Agent: AgentConfig{
			Role:                  assignment.Role,
			Specialization:        assignment.Specialization,
			Capabilities:          assignment.Capabilities,
			DefaultReasoningModel: assignment.Model,
		},
		V2: V2Config{
			DHT: DHTConfig{
				BootstrapPeers: assignment.BootstrapPeers,
			},
		},
	}

	// Handle models array
	if assignment.Model != "" {
		override.Agent.Models = []string{assignment.Model}
	}

	// Apply environment variables from assignment
	for key, value := range assignment.Environment {
		os.Setenv(key, value)
	}

	rc.over = override

	return nil
}

// StartReloadHandler starts a signal handler for configuration reload (SIGHUP)
func (rc *RuntimeConfig) StartReloadHandler(ctx context.Context) {
	sigChan := make(chan os.Signal, 1)
	signal.Notify(sigChan, syscall.SIGHUP)

	go func() {
		for {
			select {
			case <-ctx.Done():
				return
			case <-sigChan:
				fmt.Println("🔄 Received SIGHUP, reloading configuration...")
				if err := rc.LoadAssignment(ctx); err != nil {
					fmt.Printf("⚠️ Failed to reload assignment: %v\n", err)
				} else {
					fmt.Println("✅ Configuration reloaded successfully")
				}
			}
		}
	}()
}

// GetBaseConfig returns the base configuration (from environment)
func (rc *RuntimeConfig) GetBaseConfig() *Config {
	rc.mu.RLock()
	defer rc.mu.RUnlock()
	return rc.base
}

// GetEffectiveConfig returns the effective merged configuration
func (rc *RuntimeConfig) GetEffectiveConfig() *Config {
	rc.mu.RLock()
	defer rc.mu.RUnlock()

	// Start with base config
	effective := *rc.base

	// Apply overrides
	if rc.over.Agent.Role != "" {
		effective.Agent.Role = rc.over.Agent.Role
	}
	if rc.over.Agent.Specialization != "" {
		effective.Agent.Specialization = rc.over.Agent.Specialization
	}
	if len(rc.over.Agent.Capabilities) > 0 {
		effective.Agent.Capabilities = rc.over.Agent.Capabilities
	}
	if len(rc.over.Agent.Models) > 0 {
		effective.Agent.Models = rc.over.Agent.Models
	}
	if rc.over.Agent.DefaultReasoningModel != "" {
		effective.Agent.DefaultReasoningModel = rc.over.Agent.DefaultReasoningModel
	}
	if len(rc.over.V2.DHT.BootstrapPeers) > 0 {
		effective.V2.DHT.BootstrapPeers = rc.over.V2.DHT.BootstrapPeers
	}

	return &effective
}

// GetAssignmentStats returns assignment statistics for monitoring
func (rc *RuntimeConfig) GetAssignmentStats() map[string]interface{} {
	rc.mu.RLock()
	defer rc.mu.RUnlock()

	hasOverride := rc.over.Agent.Role != "" ||
		rc.over.Agent.Specialization != "" ||
		len(rc.over.Agent.Capabilities) > 0 ||
		len(rc.over.V2.DHT.BootstrapPeers) > 0

	stats := map[string]interface{}{
		"has_assignment": hasOverride,
		"assign_url":     os.Getenv("ASSIGN_URL"),
		"task_slot":      os.Getenv("TASK_SLOT"),
		"task_id":        os.Getenv("TASK_ID"),
	}

	if hasOverride {
		stats["assigned_role"] = rc.over.Agent.Role
		stats["assigned_specialization"] = rc.over.Agent.Specialization
		stats["assigned_capabilities"] = rc.over.Agent.Capabilities
		stats["assigned_models"] = rc.over.Agent.Models
		stats["bootstrap_peers_count"] = len(rc.over.V2.DHT.BootstrapPeers)
	}

	return stats
}

// InitializeAssignmentFromEnv initializes assignment from environment variables
func (rc *RuntimeConfig) InitializeAssignmentFromEnv(ctx context.Context) error {
	// Try loading from assignment URL first
	if err := rc.LoadAssignment(ctx); err != nil {
		fmt.Printf("⚠️ Failed to load assignment from URL: %v\n", err)
	}

	// Try loading from file (for config objects)
	if assignFile := os.Getenv("ASSIGNMENT_FILE"); assignFile != "" {
		if err := rc.LoadAssignmentFromFile(assignFile); err != nil {
			fmt.Printf("⚠️ Failed to load assignment from file: %v\n", err)
		}
	}

	// Start reload handler for SIGHUP
	rc.StartReloadHandler(ctx)

	return nil
}