package database

import (
	"context"
	"database/sql"
	"fmt"
	"log/slog"
	"os"
	"path/filepath"
	"sync"

	"go.uber.org/fx"
	"gorm.io/driver/sqlite"
	"gorm.io/gorm"
	"sneak.berlin/go/webhooker/internal/config"
	"sneak.berlin/go/webhooker/internal/logger"
)

// nolint:revive // WebhookDBManagerParams is a standard fx naming convention
type WebhookDBManagerParams struct {
	fx.In
	Config *config.Config
	Logger *logger.Logger
}

// WebhookDBManager manages per-webhook SQLite database files for event storage.
// Each webhook gets its own dedicated database containing Events, Deliveries,
// and DeliveryResults. Database connections are opened lazily and cached.
type WebhookDBManager struct {
	dataDir string
	dbs     sync.Map // map[webhookID]*gorm.DB
	log     *slog.Logger
}

// NewWebhookDBManager creates a new WebhookDBManager and registers lifecycle hooks.
func NewWebhookDBManager(lc fx.Lifecycle, params WebhookDBManagerParams) (*WebhookDBManager, error) {
	m := &WebhookDBManager{
		dataDir: params.Config.DataDir,
		log:     params.Logger.Get(),
	}

	// Create data directory if it doesn't exist
	if err := os.MkdirAll(m.dataDir, 0750); err != nil {
		return nil, fmt.Errorf("creating data directory %s: %w", m.dataDir, err)
	}

	lc.Append(fx.Hook{
		OnStop: func(_ context.Context) error { //nolint:revive // ctx unused but required by fx
			return m.CloseAll()
		},
	})

	m.log.Info("webhook database manager initialized", "data_dir", m.dataDir)
	return m, nil
}

// dbPath returns the filesystem path for a webhook's database file.
func (m *WebhookDBManager) dbPath(webhookID string) string {
	return filepath.Join(m.dataDir, fmt.Sprintf("events-%s.db", webhookID))
}

// openDB opens (or creates) a per-webhook SQLite database and runs migrations.
func (m *WebhookDBManager) openDB(webhookID string) (*gorm.DB, error) {
	path := m.dbPath(webhookID)
	dbURL := fmt.Sprintf("file:%s?cache=shared&mode=rwc", path)

	sqlDB, err := sql.Open("sqlite", dbURL)
	if err != nil {
		return nil, fmt.Errorf("opening webhook database %s: %w", webhookID, err)
	}

	db, err := gorm.Open(sqlite.Dialector{
		Conn: sqlDB,
	}, &gorm.Config{})
	if err != nil {
		sqlDB.Close()
		return nil, fmt.Errorf("connecting to webhook database %s: %w", webhookID, err)
	}

	// Run migrations for event-tier models only
	if err := db.AutoMigrate(&Event{}, &Delivery{}, &DeliveryResult{}); err != nil {
		sqlDB.Close()
		return nil, fmt.Errorf("migrating webhook database %s: %w", webhookID, err)
	}

	m.log.Info("opened per-webhook database", "webhook_id", webhookID, "path", path)
	return db, nil
}

// GetDB returns the database connection for a webhook, creating the database
// file lazily if it doesn't exist. This handles both new webhooks and existing
// webhooks that were created before per-webhook databases were introduced.
func (m *WebhookDBManager) GetDB(webhookID string) (*gorm.DB, error) {
	// Fast path: already open
	if val, ok := m.dbs.Load(webhookID); ok {
		cachedDB, castOK := val.(*gorm.DB)
		if !castOK {
			return nil, fmt.Errorf("invalid cached database type for webhook %s", webhookID)
		}
		return cachedDB, nil
	}

	// Slow path: open/create the database
	db, err := m.openDB(webhookID)
	if err != nil {
		return nil, err
	}

	// Store it; if another goroutine beat us, close ours and use theirs
	actual, loaded := m.dbs.LoadOrStore(webhookID, db)
	if loaded {
		// Another goroutine created it first; close our duplicate
		if sqlDB, closeErr := db.DB(); closeErr == nil {
			sqlDB.Close()
		}
		existingDB, castOK := actual.(*gorm.DB)
		if !castOK {
			return nil, fmt.Errorf("invalid cached database type for webhook %s", webhookID)
		}
		return existingDB, nil
	}

	return db, nil
}

// CreateDB explicitly creates a new per-webhook database file and runs migrations.
// This is called when a new webhook is created.
func (m *WebhookDBManager) CreateDB(webhookID string) error {
	_, err := m.GetDB(webhookID)
	return err
}

// DBExists checks if a per-webhook database file exists on disk.
func (m *WebhookDBManager) DBExists(webhookID string) bool {
	_, err := os.Stat(m.dbPath(webhookID))
	return err == nil
}

// DeleteDB closes the connection and deletes the database file for a webhook.
// This performs a hard delete — the file is permanently removed.
func (m *WebhookDBManager) DeleteDB(webhookID string) error {
	// Close and remove from cache
	if val, ok := m.dbs.LoadAndDelete(webhookID); ok {
		if gormDB, castOK := val.(*gorm.DB); castOK {
			if sqlDB, err := gormDB.DB(); err == nil {
				sqlDB.Close()
			}
		}
	}

	// Delete the main DB file and WAL/SHM files
	path := m.dbPath(webhookID)
	for _, suffix := range []string{"", "-wal", "-shm"} {
		if err := os.Remove(path + suffix); err != nil && !os.IsNotExist(err) {
			return fmt.Errorf("deleting webhook database file %s%s: %w", path, suffix, err)
		}
	}

	m.log.Info("deleted per-webhook database", "webhook_id", webhookID)
	return nil
}

// CloseAll closes all open per-webhook database connections.
// Called during application shutdown.
func (m *WebhookDBManager) CloseAll() error {
	var lastErr error
	m.dbs.Range(func(key, value interface{}) bool {
		if gormDB, castOK := value.(*gorm.DB); castOK {
			if sqlDB, err := gormDB.DB(); err == nil {
				if closeErr := sqlDB.Close(); closeErr != nil {
					lastErr = closeErr
					m.log.Error("failed to close webhook database",
						"webhook_id", key,
						"error", closeErr,
					)
				}
			}
		}
		m.dbs.Delete(key)
		return true
	})
	return lastErr
}