// Package corecfg manages the user's core (mihomo/clash) configuration:
// import, export, edit, reset, show, and applying a subscription to produce
// the final generated config file.
package corecfg

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"gopkg.in/yaml.v3"

	"gitea.epss.net.cn/klesh/ss/internal/automation"
	"gitea.epss.net.cn/klesh/ss/internal/editor"
	"gitea.epss.net.cn/klesh/ss/internal/model"
	"gitea.epss.net.cn/klesh/ss/internal/storage"
	"gitea.epss.net.cn/klesh/ss/internal/subscription"
	"gitea.epss.net.cn/klesh/ss/internal/yamlutil"
	"gitea.epss.net.cn/klesh/ss/templates"
)

// Manager manages user configuration with import, export, and edit operations.
type Manager struct {
	SubscriptionManager *subscription.Manager
	Storage             *storage.Manager
	ConfigFile          string
	GeneratedPath       string
	SubscriptionName    string
}

// New creates a CoreConfigManager. configFile/outputFile/subscriptionName may
// be empty to use the defaults (mirrors CoreConfigManager.__init__).
func New(subMgr *subscription.Manager, configFile, outputFile, subscriptionName string) (*Manager, error) {
	m := &Manager{
		SubscriptionManager: subMgr,
		Storage:             subMgr.Storage,
		SubscriptionName:    subscriptionName,
	}

	if configFile != "" {
		abs, err := resolvePath(configFile)
		if err != nil {
			return nil, err
		}
		m.ConfigFile = abs
	} else {
		m.ConfigFile = filepath.Join(subMgr.Storage.ConfigDir, "config", "core-config.yaml")
	}

	if outputFile != "" {
		abs, err := resolvePath(outputFile)
		if err != nil {
			return nil, err
		}
		m.GeneratedPath = abs
	} else {
		m.GeneratedPath = filepath.Join(subMgr.Storage.ConfigDir, "generated_config.yaml")
	}

	return m, nil
}

func resolvePath(p string) (string, error) {
	if strings.HasPrefix(p, "~") {
		home, err := os.UserHomeDir()
		if err != nil {
			return "", err
		}
		p = filepath.Join(home, strings.TrimPrefix(p, "~"))
	}
	return filepath.Abs(p)
}

func (m *Manager) ensureConfigExists() bool {
	if _, err := os.Stat(m.ConfigFile); err == nil {
		return true
	}

	if err := os.MkdirAll(filepath.Dir(m.ConfigFile), 0o755); err != nil {
		fmt.Printf("❌ Failed to create config directory: %v\n", err)
		return false
	}
	if err := os.WriteFile(m.ConfigFile, templates.DefaultCoreConfig, 0o644); err != nil {
		fmt.Printf("❌ Failed to create default config: %v\n", err)
		return false
	}
	fmt.Printf("✅ Created default config at: %s\n", m.ConfigFile)
	return true
}

// LoadConfig loads configuration from the YAML file as a raw map.
func (m *Manager) LoadConfig() map[string]interface{} {
	raw, err := os.ReadFile(m.ConfigFile)
	if err != nil {
		return map[string]interface{}{}
	}

	var data map[string]interface{}
	if err := yamlutil.Unmarshal(raw, &data); err != nil {
		fmt.Printf("Warning: Failed to load config: %v\n", err)
		return map[string]interface{}{}
	}
	if data == nil {
		return map[string]interface{}{}
	}
	return data
}

// SaveConfig writes configuration to the YAML file.
func (m *Manager) SaveConfig(config map[string]interface{}) bool {
	out, err := yaml.Marshal(config)
	if err != nil {
		fmt.Printf("Error: Failed to save config: %v\n", err)
		return false
	}
	if err := os.MkdirAll(filepath.Dir(m.ConfigFile), 0o755); err != nil {
		fmt.Printf("Error: Failed to create config directory: %v\n", err)
		return false
	}
	if err := os.WriteFile(m.ConfigFile, out, 0o644); err != nil {
		fmt.Printf("Error: Failed to save config: %v\n", err)
		return false
	}
	return true
}

// ImportConfig imports configuration from a YAML file, validating it before
// persisting.
func (m *Manager) ImportConfig(sourcePath string) bool {
	raw, err := os.ReadFile(sourcePath)
	if err != nil {
		fmt.Printf("❌ Source file not found: %s\n", sourcePath)
		return false
	}

	var data map[string]interface{}
	if err := yamlutil.Unmarshal(raw, &data); err != nil {
		fmt.Printf("❌ Invalid YAML: %v\n", err)
		return false
	}
	if data == nil {
		fmt.Println("❌ Invalid YAML format")
		return false
	}

	if err := validateConfigMap(data); err != nil {
		fmt.Printf("❌ Failed to import: %v\n", err)
		return false
	}

	m.SaveConfig(data)
	fmt.Printf("✅ Imported configuration from: %s\n", sourcePath)
	return true
}

// ExportConfig exports the current configuration to a YAML file.
func (m *Manager) ExportConfig(destinationPath string) bool {
	config := m.LoadConfig()

	if err := os.MkdirAll(filepath.Dir(destinationPath), 0o755); err != nil {
		fmt.Printf("❌ Failed to export: %v\n", err)
		return false
	}

	out, err := yaml.Marshal(config)
	if err != nil {
		fmt.Printf("❌ Failed to export: %v\n", err)
		return false
	}
	if err := os.WriteFile(destinationPath, out, 0o644); err != nil {
		fmt.Printf("❌ Failed to export: %v\n", err)
		return false
	}

	fmt.Printf("✅ Exported configuration to: %s\n", destinationPath)
	return true
}

// EditConfig opens the configuration in the system default editor, backing
// it up first and restoring on failure to open the editor.
func (m *Manager) EditConfig() bool {
	if !m.ensureConfigExists() {
		return false
	}

	backupPath := strings.TrimSuffix(m.ConfigFile, filepath.Ext(m.ConfigFile)) + ".yaml.backup"
	if _, err := os.Stat(m.ConfigFile); err == nil {
		if data, err := os.ReadFile(m.ConfigFile); err == nil {
			os.WriteFile(backupPath, data, 0o644)
		}
	}

	if !openInEditor(m.ConfigFile) {
		return false
	}

	m.LoadConfig()
	fmt.Println("✅ Configuration edited successfully")
	return true
}

// ResetConfig resets configuration to default values.
func (m *Manager) ResetConfig() bool {
	if err := os.MkdirAll(filepath.Dir(m.ConfigFile), 0o755); err != nil {
		fmt.Printf("❌ Failed to create config directory: %v\n", err)
		return false
	}
	if err := os.WriteFile(m.ConfigFile, templates.DefaultCoreConfig, 0o644); err != nil {
		fmt.Printf("❌ Failed to reset configuration: %v\n", err)
		return false
	}
	fmt.Println("✅ Configuration reset to default values")
	return true
}

// ShowConfig prints the current configuration.
func (m *Manager) ShowConfig() {
	config := m.LoadConfig()
	out, _ := yaml.Marshal(config)
	fmt.Println(string(out))
}

var essentialDefaults = map[string]interface{}{
	"port":                7890,
	"socks-port":          7891,
	"mixed-port":          7890,
	"allow-lan":           false,
	"mode":                "rule",
	"log-level":           "info",
	"external-controller": "127.0.0.1:9090",
	"ipv6":                true,
}

func defaultDNSConfig() map[string]interface{} {
	return map[string]interface{}{
		"enable":        true,
		"listen":        "0.0.0.0:53",
		"enhanced-mode": "fake-ip",
		"fake-ip-range": "198.18.0.1/16",
		"nameserver": []interface{}{
			"https://doh.pub/dns-query",
			"https://dns.alidns.com/dns-query",
		},
		"fallback": []interface{}{
			"https://1.1.1.1/dns-query",
			"https://8.8.8.8/dns-query",
		},
	}
}

// Apply applies every active (or the explicitly --subscription-selected)
// subscription to generate the final config file: merging all of them
// together (each proxy name prefixed with its source subscription's name to
// avoid collisions), merging that with user configuration, filling in
// essential defaults, running any `ssm:` automation rules, and finally
// executing any registered hooks.
func (m *Manager) Apply() bool {
	config := m.LoadConfig()

	// The "ssm" key is this tool's own automation metadata, not a real
	// mihomo/clash config key — pull it out before anything else touches
	// config, so it never leaks into the generated file.
	ssmRaw, hasSSM := config["ssm"]
	delete(config, "ssm")

	subs := m.resolveSubscriptions()
	if len(subs) == 0 {
		return false
	}

	subscriptionData, proxies, ok := m.mergeSubscriptions(subs)
	if !ok {
		return false
	}

	finalConfig := deepMerge(subscriptionData, config)

	for key, defaultValue := range essentialDefaults {
		if _, ok := finalConfig[key]; !ok {
			finalConfig[key] = defaultValue
		}
	}

	if _, ok := finalConfig["dns"]; !ok {
		finalConfig["dns"] = defaultDNSConfig()
	}

	if hasSSM {
		ssmConfig, err := automation.ParseConfig(ssmRaw)
		if err != nil {
			fmt.Printf("❌ Invalid ssm automation config: %v\n", err)
		} else {
			for _, err := range automation.Apply(finalConfig, ssmConfig, proxies) {
				fmt.Printf("⚠️  ssm automation: %v\n", err)
			}
		}
	}

	out, err := yaml.Marshal(finalConfig)
	if err != nil {
		fmt.Printf("❌ Failed to apply configuration: %v\n", err)
		return false
	}
	if err := os.WriteFile(m.GeneratedPath, out, 0o644); err != nil {
		fmt.Printf("❌ Failed to apply configuration: %v\n", err)
		return false
	}

	names := make([]string, len(subs))
	for i, sub := range subs {
		names[i] = sub.Name
	}
	fmt.Printf("✅ Generated final configuration: %s\n", m.GeneratedPath)
	fmt.Printf("   Active subscription(s): %s\n", strings.Join(names, ", "))

	m.executeHooks(m.GeneratedPath)

	return true
}

// resolveSubscriptions returns the subscription(s) to apply: just the
// explicitly --subscription-selected one if set, otherwise every currently
// active subscription.
func (m *Manager) resolveSubscriptions() []*model.Subscription {
	if m.SubscriptionName != "" {
		sub, ok := m.SubscriptionManager.Data.Subscriptions[m.SubscriptionName]
		if !ok {
			fmt.Printf("❌ Subscription '%s' not found\n", m.SubscriptionName)
			return nil
		}
		return []*model.Subscription{sub}
	}
	subs := m.SubscriptionManager.Data.GetActiveSubscriptions()
	if len(subs) == 0 {
		fmt.Println("❌ No active subscription found")
		return nil
	}
	return subs
}

// mergeSubscriptions reads and parses every resolved subscription's
// downloaded YAML, prefixes each proxy's name with its source subscription's
// name (avoiding collisions when multiple subscriptions are merged), and
// deep-merges them all together (later subscriptions' scalar/map values win
// over earlier ones on conflicting keys; lists — notably "proxies" — are
// concatenated). Returns the combined data, the full proxy pool for ssm
// automation matching, and false if any resolved subscription's file is
// missing or invalid.
func (m *Manager) mergeSubscriptions(subs []*model.Subscription) (map[string]interface{}, []automation.ProxyRef, bool) {
	combined := map[string]interface{}{}
	var proxies []automation.ProxyRef
	var selectionGroups []map[string]interface{}

	for _, sub := range subs {
		filePath := sub.GetFilePath(m.Storage.ConfigDir)
		if _, err := os.Stat(filePath); err != nil {
			fmt.Printf("❌ Subscription file not found for '%s'. Please refresh the subscription first.\n", sub.Name)
			return nil, nil, false
		}

		content, err := os.ReadFile(filePath)
		if err != nil {
			fmt.Printf("❌ Failed to read subscription '%s': %v\n", sub.Name, err)
			return nil, nil, false
		}

		var data map[string]interface{}
		if err := yamlutil.Unmarshal(content, &data); err != nil {
			fmt.Printf("❌ Invalid YAML in subscription '%s': %v\n", sub.Name, err)
			return nil, nil, false
		}
		if data == nil {
			data = map[string]interface{}{}
		}

		proxies = append(proxies, automation.PrefixProxyNames(sub.Name, data)...)
		if group := popFirstProxyGroup(data); group != nil {
			selectionGroups = append(selectionGroups, group)
		}
		combined = deepMerge(combined, data)
	}

	combined["rules"] = dedupeMatchRule(combined["rules"])
	mergeProxySelection(combined, selectionGroups)

	return combined, proxies, true
}

// dedupeMatchRule drops every "MATCH,..." catch-all rule contributed by the
// merged subscriptions — each one covers all their own proxies, so once
// concatenated they'd shadow all subsequent subscriptions' rules — and
// appends a single "MATCH,all proxies" catch-all in their place.
func dedupeMatchRule(rulesRaw interface{}) interface{} {
	rules, ok := rulesRaw.([]interface{})
	if !ok {
		return rulesRaw
	}

	filtered := make([]interface{}, 0, len(rules)+1)
	for _, item := range rules {
		if line, ok := item.(string); ok && strings.HasPrefix(line, "MATCH,") {
			continue
		}
		filtered = append(filtered, item)
	}

	return append(filtered, "MATCH,all proxies")
}

func openInEditor(path string) bool {
	return editor.OpenFileInEditor(path)
}