package config

import (
	"encoding/json"
	"log"
	"os"
	"sync"
	"time"
)

// CredentialType represents supported DNS provider types
type CredentialType string

const (
	CredentialAliDNS     CredentialType = "alidns"
	CredentialCloudflare CredentialType = "cloudflare"
	CredentialDNSPod     CredentialType = "dnspod"
)

// CredentialField describes a single field of a credential type
type CredentialField struct {
	Key      string `json:"key"`
	Label    string `json:"label"`
	Type     string `json:"type"` // text, password
	Required bool   `json:"required"`
}

// CredentialTypeMeta returns field definitions for each provider type
func CredentialTypeMeta(ctype CredentialType) []CredentialField {
	switch ctype {
	case CredentialAliDNS:
		return []CredentialField{
			{Key: "ali_key", Label: "AccessKey ID", Type: "text", Required: true},
			{Key: "ali_secret", Label: "AccessKey Secret", Type: "password", Required: true},
		}
	case CredentialCloudflare:
		return []CredentialField{
			{Key: "cf_api_token", Label: "API Token", Type: "password", Required: true},
		}
	case CredentialDNSPod:
		return []CredentialField{
			{Key: "dnspod_id", Label: "ID", Type: "text", Required: true},
			{Key: "dnspod_key", Label: "Key", Type: "password", Required: true},
		}
	default:
		return nil
	}
}

// Credential holds saved DNS provider credentials
type Credential struct {
	ID       uint           `json:"id"`
	Name     string         `json:"name"`      // user-friendly name
	Type     CredentialType `json:"type"`       // alidns, cloudflare, dnspod
	Data     string         `json:"data"`       // JSON string of key-value pairs
	Masked   string         `json:"masked"`     // masked display version of data
	CreatedAt time.Time     `json:"created_at"`
	UpdatedAt time.Time     `json:"updated_at"`
}

// CredentialStore manages credential persistence
type CredentialStore struct {
	mu     sync.RWMutex
	data   map[uint]*Credential
	path   string
	nextID uint
}

var CredStore *CredentialStore

// InitCredentialStore initializes the credential store
func InitCredentialStore(cfg *Config) {
	CredStore = &CredentialStore{
		data: make(map[uint]*Credential),
		path: cfg.DataDir + "/credentials.json",
	}

	if err := CredStore.Load(); err != nil {
		log.Printf("No existing credential store: %v, starting fresh", err)
	}

	log.Println("Credential store initialized successfully")
}

// Load reads credentials from JSON file
func (s *CredentialStore) Load() error {
	s.mu.Lock()
	defer s.mu.Unlock()

	data, err := os.ReadFile(s.path)
	if err != nil {
		return err
	}

	var creds []*Credential
	if err := json.Unmarshal(data, &creds); err != nil {
		return err
	}

	s.data = make(map[uint]*Credential)
	s.nextID = 0
	for _, c := range creds {
		s.data[c.ID] = c
		if c.ID >= s.nextID {
			s.nextID = c.ID + 1
		}
	}
	return nil
}

func (s *CredentialStore) save() error {
	creds := make([]*Credential, 0, len(s.data))
	for _, c := range s.data {
		creds = append(creds, c)
	}
	data, err := json.MarshalIndent(creds, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(s.path, data, 0600)
}

// GetAll returns all credentials
func (s *CredentialStore) GetAll() []*Credential {
	s.mu.RLock()
	defer s.mu.RUnlock()
	result := make([]*Credential, 0, len(s.data))
	for _, c := range s.data {
		clone := *c
		clone.Data = "" // don't expose secrets in list
		result = append(result, &clone)
	}
	// Sort by ID descending (newest first)
	for i := 0; i < len(result)-1; i++ {
		for j := i + 1; j < len(result); j++ {
			if result[i].ID < result[j].ID {
				result[i], result[j] = result[j], result[i]
			}
		}
	}
	return result
}

// GetByID returns a credential with secrets (for internal use)
func (s *CredentialStore) GetByID(id uint) *Credential {
	s.mu.RLock()
	defer s.mu.RUnlock()
	c := s.data[id]
	if c == nil {
		return nil
	}
	clone := *c
	return &clone
}

// Create adds a new credential
func (s *CredentialStore) Create(cred *Credential) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	cred.ID = s.nextID
	s.nextID++
	now := time.Now()
	cred.CreatedAt = now
	cred.UpdatedAt = now
	cred.Masked = maskCredentialData(cred.Type, cred.Data)

	s.data[cred.ID] = cred
	return s.save()
}

// Update modifies an existing credential, keeping data if masked
func (s *CredentialStore) Update(cred *Credential) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	existing, ok := s.data[cred.ID]
	if !ok {
		return nil
	}

	// If data is masked, keep the existing one
	if cred.Data == "********" {
		cred.Data = existing.Data
	}

	cred.CreatedAt = existing.CreatedAt
	cred.UpdatedAt = time.Now()
	cred.Masked = maskCredentialData(cred.Type, cred.Data)

	s.data[cred.ID] = cred
	return s.save()
}

// Delete removes a credential
func (s *CredentialStore) Delete(id uint) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	delete(s.data, id)
	return s.save()
}

// maskCredentialData creates a masked version for API display
func maskCredentialData(ctype CredentialType, dataJSON string) string {
	var raw map[string]string
	if err := json.Unmarshal([]byte(dataJSON), &raw); err != nil {
		return "{}"
	}
	masked := make(map[string]string)
	for k, v := range raw {
		if len(v) > 4 {
			masked[k] = v[:4] + "****"
		} else {
			masked[k] = "****"
		}
	}
	b, _ := json.Marshal(masked)
	return string(b)
}

// GetDataMap parses the credential data JSON into a map
func (c *Credential) GetDataMap() map[string]string {
	result := make(map[string]string)
	json.Unmarshal([]byte(c.Data), &result)
	return result
}