package backup

import (
	"context"
	"fmt"
	"log"
	"strings"
	"sync"
	"time"

	"gitea.dooplex.hu/admin/felhom-controller/internal/config"
	"gitea.dooplex.hu/admin/felhom-controller/internal/monitor"
)

// Manager orchestrates database dumps and restic backups.
type Manager struct {
	cfg    *config.Config
	restic *ResticManager
	logger *log.Logger
	pinger *monitor.Pinger

	mu              sync.Mutex
	lastDBDump      *DBDumpStatus
	lastBackup      *BackupStatus
	running         bool
	snapshotHistory []SnapshotRecord // ring buffer, last 20 entries
	lastCheckTime   time.Time
	lastCheckOK     bool

	// Cached status for page rendering (refreshed periodically)
	cachedStatus *FullBackupStatus
	cacheTime    time.Time

	// AfterBackup is called after a backup completes to refresh the cache.
	// Set by main.go to avoid circular import with scheduler.
	AfterBackup func()
}

// SnapshotRecord combines restic snapshot metadata with our run stats.
type SnapshotRecord struct {
	SnapshotID   string        `json:"snapshot_id"`
	Time         time.Time     `json:"time"`
	FilesNew     int           `json:"files_new"`
	FilesChanged int           `json:"files_changed"`
	DataAdded    string        `json:"data_added"`
	Duration     time.Duration `json:"duration"`
	Success      bool          `json:"success"`
	HasStats     bool          `json:"has_stats"` // false for historical entries loaded from restic
}

// FullBackupStatus contains everything the backup page needs.
type FullBackupStatus struct {
	Enabled bool
	Running bool

	// DB Dumps
	LastDBDump    *DBDumpStatus
	DumpFiles     []DumpFileInfo
	DiscoveredDBs []DiscoveredDB

	// Restic
	LastBackup      *BackupStatus
	SnapshotHistory []SnapshotRecord
	RepoStats       *RepoStats

	// Schedule
	DBDumpSchedule string
	ResticSchedule string
	PruneSchedule  string
	NextDBDump     time.Time
	NextBackup     time.Time
	Retention      config.RetentionConfig

	// Repository health
	RepoPath      string
	BackupPaths   []string
	LastCheckTime time.Time
	LastCheckOK   bool

	// Remote (placeholder)
	RemoteEnabled bool
}

// DBDumpStatus holds the last DB dump result.
type DBDumpStatus struct {
	LastRun  time.Time
	Results  []DumpResult
	Success  bool
	Duration time.Duration
}

// BackupStatus holds the last backup result.
type BackupStatus struct {
	LastRun   time.Time
	Snapshot  *SnapshotResult
	Success   bool
	Duration  time.Duration
	RepoStats *RepoStats
}

// NewManager creates a new backup manager.
func NewManager(cfg *config.Config, pinger *monitor.Pinger, logger *log.Logger) *Manager {
	return &Manager{
		cfg:    cfg,
		restic: NewResticManager(cfg, logger),
		logger: logger,
		pinger: pinger,
	}
}

// RunDBDumps discovers and dumps all databases.
func (m *Manager) RunDBDumps(ctx context.Context) error {
	start := time.Now()
	m.logger.Printf("[INFO] Starting database dump run")

	dbs, err := DiscoverDatabases(ctx, m.logger)
	if err != nil {
		m.logger.Printf("[ERROR] Database discovery failed: %v", err)
		return err
	}

	if len(dbs) == 0 {
		m.logger.Printf("[INFO] No database containers found")
		m.mu.Lock()
		m.lastDBDump = &DBDumpStatus{
			LastRun:  time.Now(),
			Success:  true,
			Duration: time.Since(start),
		}
		m.mu.Unlock()
		return nil
	}

	m.logger.Printf("[INFO] Discovered %d database(s): %s", len(dbs), dbNames(dbs))

	results := DumpAll(ctx, dbs, m.cfg.Paths.DBDumpDir, m.logger)

	// Check results
	allOK := true
	var summary []string
	var totalSize int64
	for _, r := range results {
		if r.Error != nil {
			allOK = false
			summary = append(summary, fmt.Sprintf("FAIL %s: %v", r.DB.ContainerName, r.Error))
			m.logger.Printf("[ERROR] DB dump failed for %s: %v", r.DB.ContainerName, r.Error)
		} else {
			totalSize += r.Size
			summary = append(summary, fmt.Sprintf("OK %s (%s)", r.DB.ContainerName, formatBytes(r.Size)))
		}
	}

	duration := time.Since(start)
	m.mu.Lock()
	m.lastDBDump = &DBDumpStatus{
		LastRun:  time.Now(),
		Results:  results,
		Success:  allOK,
		Duration: duration,
	}
	m.mu.Unlock()

	// Ping healthcheck
	uuid := m.cfg.Monitoring.PingUUIDs.DBDump
	body := fmt.Sprintf("DB dump: %d databases, %s total\n%s",
		len(results), formatBytes(totalSize), strings.Join(summary, "\n"))

	if allOK {
		m.pinger.Ping(uuid, body)
		m.logger.Printf("[INFO] DB dump completed: %d databases, %s total (%s)",
			len(results), formatBytes(totalSize), duration.Round(time.Millisecond))
	} else {
		m.pinger.Fail(uuid, body)
		return fmt.Errorf("some database dumps failed")
	}

	return nil
}

// RunBackup runs a restic backup snapshot.
func (m *Manager) RunBackup(ctx context.Context) error {
	start := time.Now()
	m.logger.Printf("[INFO] Starting restic backup")

	// Ensure repo is initialized
	if err := m.restic.EnsureInitialized(); err != nil {
		m.logger.Printf("[ERROR] Restic init failed: %v", err)
		m.pinger.Fail(m.cfg.Monitoring.PingUUIDs.Backup, fmt.Sprintf("Restic init failed: %v", err))
		return err
	}

	// Backup paths
	paths := []string{
		m.cfg.Paths.StacksDir,
		m.cfg.Paths.DBDumpDir,
		"/opt/docker/felhom-controller/controller.yaml",
	}
	tags := []string{"felhom", m.cfg.Customer.ID}

	result, err := m.restic.Snapshot(paths, tags)
	if err != nil {
		m.logger.Printf("[ERROR] Restic backup failed: %v", err)
		m.pinger.Fail(m.cfg.Monitoring.PingUUIDs.Backup, fmt.Sprintf("Backup failed: %v", err))

		m.mu.Lock()
		m.lastBackup = &BackupStatus{
			LastRun:  time.Now(),
			Success:  false,
			Duration: time.Since(start),
		}
		m.mu.Unlock()
		return err
	}

	// Prune check (weekly — Sunday)
	if shouldPrune(m.cfg.Backup.PruneSchedule) {
		m.logger.Printf("[INFO] Running weekly prune")
		if err := m.restic.Prune(m.cfg.Backup.Retention); err != nil {
			m.logger.Printf("[WARN] Restic prune failed: %v", err)
		}
		checkErr := m.restic.Check()
		if checkErr != nil {
			m.logger.Printf("[WARN] Restic check failed: %v", checkErr)
		}
		m.mu.Lock()
		m.lastCheckTime = time.Now()
		m.lastCheckOK = checkErr == nil
		m.mu.Unlock()
	}

	// Get stats
	stats, _ := m.restic.Stats()

	duration := time.Since(start)
	m.mu.Lock()
	m.lastBackup = &BackupStatus{
		LastRun:   time.Now(),
		Snapshot:  result,
		Success:   true,
		Duration:  duration,
		RepoStats: stats,
	}
	// Append to snapshot history
	m.appendSnapshotRecord(SnapshotRecord{
		SnapshotID:   result.SnapshotID,
		Time:         time.Now(),
		FilesNew:     result.FilesNew,
		FilesChanged: result.FilesChanged,
		DataAdded:    result.DataAdded,
		Duration:     duration,
		Success:      true,
		HasStats:     true,
	})
	m.mu.Unlock()

	body := fmt.Sprintf("Backup OK\nSnapshot: %s\nNew files: %d, Changed: %d\nData added: %s\nDuration: %s",
		result.SnapshotID, result.FilesNew, result.FilesChanged, result.DataAdded,
		duration.Round(time.Second))
	m.pinger.Ping(m.cfg.Monitoring.PingUUIDs.Backup, body)

	m.logger.Printf("[INFO] Restic backup completed: snapshot %s, %d new, %d changed, %s added (%s)",
		result.SnapshotID, result.FilesNew, result.FilesChanged, result.DataAdded,
		duration.Round(time.Millisecond))

	// Refresh cache so the page shows updated data immediately
	if m.AfterBackup != nil {
		m.AfterBackup()
	}

	return nil
}

// RunFullBackup runs DB dumps followed by restic backup.
func (m *Manager) RunFullBackup(ctx context.Context) error {
	m.mu.Lock()
	if m.running {
		m.mu.Unlock()
		return fmt.Errorf("backup already in progress")
	}
	m.running = true
	m.mu.Unlock()

	defer func() {
		m.mu.Lock()
		m.running = false
		m.mu.Unlock()
	}()

	// Step 1: DB dumps
	if err := m.RunDBDumps(ctx); err != nil {
		m.logger.Printf("[WARN] DB dump had errors, continuing with backup anyway")
	}

	// Step 2: Restic backup
	return m.RunBackup(ctx)
}

// GetStatus returns the current backup status.
func (m *Manager) GetStatus() (*DBDumpStatus, *BackupStatus) {
	m.mu.Lock()
	defer m.mu.Unlock()
	return m.lastDBDump, m.lastBackup
}

// GetRepoStats returns repository statistics.
func (m *Manager) GetRepoStats() (*RepoStats, error) {
	return m.restic.Stats()
}

// IsRunning returns whether a backup is currently in progress.
func (m *Manager) IsRunning() bool {
	m.mu.Lock()
	defer m.mu.Unlock()
	return m.running
}

func shouldPrune(schedule string) bool {
	loc, err := time.LoadLocation("Europe/Budapest")
	if err != nil {
		loc = time.UTC
	}
	now := time.Now().In(loc)

	switch strings.ToLower(schedule) {
	case "weekly":
		return now.Weekday() == time.Sunday
	case "daily":
		return true
	default:
		return now.Weekday() == time.Sunday
	}
}

// appendSnapshotRecord adds a record to the ring buffer (max 20). Caller must hold m.mu.
func (m *Manager) appendSnapshotRecord(rec SnapshotRecord) {
	m.snapshotHistory = append(m.snapshotHistory, rec)
	if len(m.snapshotHistory) > 20 {
		m.snapshotHistory = m.snapshotHistory[len(m.snapshotHistory)-20:]
	}
}

// LoadSnapshotHistory populates the snapshot history from restic on startup.
func (m *Manager) LoadSnapshotHistory() {
	snapshots, err := m.restic.ListSnapshots(20)
	if err != nil {
		m.logger.Printf("[WARN] Could not load snapshot history: %v", err)
		return
	}

	m.mu.Lock()
	defer m.mu.Unlock()

	for _, s := range snapshots {
		m.snapshotHistory = append(m.snapshotHistory, SnapshotRecord{
			SnapshotID: s.ID,
			Time:       s.Time,
			HasStats:   false, // historical — no delta stats available
			Success:    true,
		})
	}
	if len(m.snapshotHistory) > 20 {
		m.snapshotHistory = m.snapshotHistory[len(m.snapshotHistory)-20:]
	}
	m.logger.Printf("[INFO] Loaded %d historical snapshots", len(m.snapshotHistory))
}

// RefreshCache updates the cached full status. Called by scheduler every 5 minutes
// and after each backup run.
func (m *Manager) RefreshCache(nextDBDump, nextBackup time.Time) {
	status := &FullBackupStatus{
		Enabled: m.cfg.Backup.Enabled,

		DBDumpSchedule: m.cfg.Backup.DBDumpSchedule,
		ResticSchedule: m.cfg.Backup.ResticSchedule,
		PruneSchedule:  m.cfg.Backup.PruneSchedule,
		NextDBDump:     nextDBDump,
		NextBackup:     nextBackup,
		Retention:      m.cfg.Backup.Retention,

		RepoPath: m.cfg.Backup.ResticRepo,
		BackupPaths: []string{
			m.cfg.Paths.StacksDir,
			m.cfg.Paths.DBDumpDir,
			"/opt/docker/felhom-controller/controller.yaml",
		},
	}

	// Expensive calls (outside lock)
	if stats, err := m.restic.Stats(); err == nil {
		status.RepoStats = stats
	}
	if files, err := ListDumpFiles(m.cfg.Paths.DBDumpDir); err == nil {
		status.DumpFiles = files
	}
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	if dbs, err := DiscoverDatabases(ctx, m.logger); err == nil {
		status.DiscoveredDBs = dbs
	}

	// Fill in dynamic fields under lock
	m.mu.Lock()
	status.Running = m.running
	status.LastDBDump = m.lastDBDump
	status.LastBackup = m.lastBackup
	status.LastCheckTime = m.lastCheckTime
	status.LastCheckOK = m.lastCheckOK
	status.SnapshotHistory = make([]SnapshotRecord, len(m.snapshotHistory))
	copy(status.SnapshotHistory, m.snapshotHistory)
	m.cachedStatus = status
	m.cacheTime = time.Now()
	m.mu.Unlock()

	// Reverse so newest first
	for i, j := 0, len(status.SnapshotHistory)-1; i < j; i, j = i+1, j-1 {
		status.SnapshotHistory[i], status.SnapshotHistory[j] = status.SnapshotHistory[j], status.SnapshotHistory[i]
	}

	m.logger.Printf("[INFO] Backup status cache refreshed")
}

// GetFullStatus returns the cached backup status for page rendering.
// Returns instantly — no subprocess calls.
func (m *Manager) GetFullStatus(nextDBDump, nextBackup time.Time) *FullBackupStatus {
	m.mu.Lock()
	defer m.mu.Unlock()

	if m.cachedStatus != nil {
		// Update dynamic fields that don't need subprocess calls
		m.cachedStatus.Running = m.running
		m.cachedStatus.NextDBDump = nextDBDump
		m.cachedStatus.NextBackup = nextBackup
		m.cachedStatus.LastDBDump = m.lastDBDump
		m.cachedStatus.LastBackup = m.lastBackup
		// Update snapshot history
		m.cachedStatus.SnapshotHistory = make([]SnapshotRecord, len(m.snapshotHistory))
		copy(m.cachedStatus.SnapshotHistory, m.snapshotHistory)
		// Reverse so newest first
		for i, j := 0, len(m.cachedStatus.SnapshotHistory)-1; i < j; i, j = i+1, j-1 {
			m.cachedStatus.SnapshotHistory[i], m.cachedStatus.SnapshotHistory[j] = m.cachedStatus.SnapshotHistory[j], m.cachedStatus.SnapshotHistory[i]
		}

		// Synthesize LastBackup from snapshot history if not in memory (e.g., after restart)
		if m.cachedStatus.LastBackup == nil && len(m.cachedStatus.SnapshotHistory) > 0 {
			latest := m.cachedStatus.SnapshotHistory[0] // already reversed, newest first
			m.cachedStatus.LastBackup = &BackupStatus{
				LastRun: latest.Time,
				Success: latest.Success,
				Snapshot: &SnapshotResult{
					SnapshotID: latest.SnapshotID,
				},
			}
		}

		// Synthesize LastDBDump from DumpFiles on disk if not in memory
		if m.cachedStatus.LastDBDump == nil && len(m.cachedStatus.DumpFiles) > 0 {
			var results []DumpResult
			var latestTime time.Time
			for _, f := range m.cachedStatus.DumpFiles {
				results = append(results, DumpResult{
					DB:       DiscoveredDB{StackName: f.StackName, DBType: f.DBType, ContainerName: f.StackName},
					FilePath: f.FileName,
					Size:     f.Size,
				})
				if f.ModTime.After(latestTime) {
					latestTime = f.ModTime
				}
			}
			m.cachedStatus.LastDBDump = &DBDumpStatus{
				LastRun: latestTime,
				Results: results,
				Success: true,
			}
		}

		return m.cachedStatus
	}

	// No cache yet — return a minimal status (first page load before cache is populated)
	return &FullBackupStatus{
		Enabled:        m.cfg.Backup.Enabled,
		Running:        m.running,
		LastDBDump:     m.lastDBDump,
		LastBackup:     m.lastBackup,
		DBDumpSchedule: m.cfg.Backup.DBDumpSchedule,
		ResticSchedule: m.cfg.Backup.ResticSchedule,
		PruneSchedule:  m.cfg.Backup.PruneSchedule,
		NextDBDump:     nextDBDump,
		NextBackup:     nextBackup,
		Retention:      m.cfg.Backup.Retention,
		RepoPath:       m.cfg.Backup.ResticRepo,
		LastCheckTime:  m.lastCheckTime,
		LastCheckOK:    m.lastCheckOK,
		BackupPaths: []string{
			m.cfg.Paths.StacksDir,
			m.cfg.Paths.DBDumpDir,
			"/opt/docker/felhom-controller/controller.yaml",
		},
	}
}

func dbNames(dbs []DiscoveredDB) string {
	var names []string
	for _, db := range dbs {
		names = append(names, fmt.Sprintf("%s(%s)", db.ContainerName, db.DBType))
	}
	return strings.Join(names, ", ")
}