package store

import (
	"database/sql"
	"embed"
	"encoding/json"
	"fmt"
	"io/fs"
	"sort"
	"strings"
	"time"

	"github.com/inou-ai/messaging-center/internal/core"
	_ "github.com/mattn/go-sqlite3"
)

//go:embed migrations/*.sql
var migrations embed.FS

// Store provides database operations.
type Store struct {
	db *sql.DB
}

// New creates a new Store and runs migrations.
func New(dbPath string) (*Store, error) {
	db, err := sql.Open("sqlite3", dbPath+"?_journal_mode=WAL&_foreign_keys=on")
	if err != nil {
		return nil, fmt.Errorf("open database: %w", err)
	}

	s := &Store{db: db}
	if err := s.migrate(); err != nil {
		db.Close()
		return nil, fmt.Errorf("migrate: %w", err)
	}

	return s, nil
}

// Close closes the database connection.
func (s *Store) Close() error {
	return s.db.Close()
}

// migrate runs all SQL migrations in order.
func (s *Store) migrate() error {
	// Create migrations table
	_, err := s.db.Exec(`
		CREATE TABLE IF NOT EXISTS migrations (
			id INTEGER PRIMARY KEY,
			name TEXT NOT NULL UNIQUE,
			applied_at DATETIME DEFAULT CURRENT_TIMESTAMP
		)
	`)
	if err != nil {
		return fmt.Errorf("create migrations table: %w", err)
	}

	// Get applied migrations
	rows, err := s.db.Query("SELECT name FROM migrations")
	if err != nil {
		return fmt.Errorf("query migrations: %w", err)
	}
	applied := make(map[string]bool)
	for rows.Next() {
		var name string
		if err := rows.Scan(&name); err != nil {
			rows.Close()
			return err
		}
		applied[name] = true
	}
	rows.Close()

	// Get migration files
	entries, err := fs.ReadDir(migrations, "migrations")
	if err != nil {
		return fmt.Errorf("read migrations dir: %w", err)
	}

	// Sort by name
	var files []string
	for _, e := range entries {
		if !e.IsDir() && strings.HasSuffix(e.Name(), ".sql") {
			files = append(files, e.Name())
		}
	}
	sort.Strings(files)

	// Apply unapplied migrations
	for _, name := range files {
		if applied[name] {
			continue
		}

		data, err := migrations.ReadFile("migrations/" + name)
		if err != nil {
			return fmt.Errorf("read migration %s: %w", name, err)
		}

		tx, err := s.db.Begin()
		if err != nil {
			return fmt.Errorf("begin transaction: %w", err)
		}

		if _, err := tx.Exec(string(data)); err != nil {
			tx.Rollback()
			return fmt.Errorf("execute migration %s: %w", name, err)
		}

		if _, err := tx.Exec("INSERT INTO migrations (name) VALUES (?)", name); err != nil {
			tx.Rollback()
			return fmt.Errorf("record migration %s: %w", name, err)
		}

		if err := tx.Commit(); err != nil {
			return fmt.Errorf("commit migration %s: %w", name, err)
		}
	}

	return nil
}

// DB returns the underlying database connection.
func (s *Store) DB() *sql.DB {
	return s.db
}

// CreateMessage inserts a new message.
func (s *Store) CreateMessage(m *core.Message) error {
	raw, _ := json.Marshal(m.Raw)
	from, _ := json.Marshal(m.From)
	to, _ := json.Marshal(m.To)

	_, err := s.db.Exec(`
		INSERT INTO messages (id, source, direction, from_contact, to_contact, timestamp, type, subject, body, body_html, status, raw, created_at, updated_at)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
	`, m.ID, m.Source, m.Direction, from, to, m.Timestamp, m.Type, m.Subject, m.Body, m.BodyHTML, m.Status, raw, m.CreatedAt, m.UpdatedAt)
	return err
}

// GetMessage retrieves a message by ID.
func (s *Store) GetMessage(id string) (*core.Message, error) {
	var m core.Message
	var from, to, raw []byte

	err := s.db.QueryRow(`
		SELECT id, source, direction, from_contact, to_contact, timestamp, type, subject, body, body_html, status, raw, created_at, updated_at
		FROM messages WHERE id = ?
	`, id).Scan(&m.ID, &m.Source, &m.Direction, &from, &to, &m.Timestamp, &m.Type, &m.Subject, &m.Body, &m.BodyHTML, &m.Status, &raw, &m.CreatedAt, &m.UpdatedAt)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}

	json.Unmarshal(from, &m.From)
	json.Unmarshal(to, &m.To)
	m.Raw = raw

	// Load attachments
	attachments, err := s.GetAttachmentsByMessage(id)
	if err != nil {
		return nil, err
	}
	m.Attachments = attachments

	return &m, nil
}

// ListMessages retrieves messages with optional filters.
func (s *Store) ListMessages(f core.MessageFilter) ([]core.Message, error) {
	query := `SELECT id, source, direction, from_contact, to_contact, timestamp, type, subject, body, body_html, status, raw, created_at, updated_at FROM messages WHERE 1=1`
	args := []any{}

	if f.Source != "" {
		query += " AND source = ?"
		args = append(args, f.Source)
	}
	if f.Direction != "" {
		query += " AND direction = ?"
		args = append(args, f.Direction)
	}
	if f.Type != "" {
		query += " AND type = ?"
		args = append(args, f.Type)
	}
	if f.Since != nil {
		query += " AND timestamp >= ?"
		args = append(args, *f.Since)
	}
	if f.Until != nil {
		query += " AND timestamp <= ?"
		args = append(args, *f.Until)
	}

	query += " ORDER BY timestamp DESC"

	if f.Limit > 0 {
		query += fmt.Sprintf(" LIMIT %d", f.Limit)
	} else {
		query += " LIMIT 50"
	}
	if f.Offset > 0 {
		query += fmt.Sprintf(" OFFSET %d", f.Offset)
	}

	rows, err := s.db.Query(query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var messages []core.Message
	for rows.Next() {
		var m core.Message
		var from, to, raw []byte

		if err := rows.Scan(&m.ID, &m.Source, &m.Direction, &from, &to, &m.Timestamp, &m.Type, &m.Subject, &m.Body, &m.BodyHTML, &m.Status, &raw, &m.CreatedAt, &m.UpdatedAt); err != nil {
			return nil, err
		}

		json.Unmarshal(from, &m.From)
		json.Unmarshal(to, &m.To)
		m.Raw = raw

		messages = append(messages, m)
	}

	return messages, nil
}

// CreateAttachment inserts a new attachment.
func (s *Store) CreateAttachment(a *core.Attachment) error {
	_, err := s.db.Exec(`
		INSERT INTO attachments (id, message_id, type, filename, size, local_path, transcription, status)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?)
	`, a.ID, a.MessageID, a.Type, a.Filename, a.Size, a.LocalPath, a.Transcription, a.Status)
	return err
}

// GetAttachmentsByMessage retrieves all attachments for a message.
func (s *Store) GetAttachmentsByMessage(messageID string) ([]core.Attachment, error) {
	rows, err := s.db.Query(`
		SELECT id, message_id, type, filename, size, local_path, transcription, status
		FROM attachments WHERE message_id = ?
	`, messageID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var attachments []core.Attachment
	for rows.Next() {
		var a core.Attachment
		if err := rows.Scan(&a.ID, &a.MessageID, &a.Type, &a.Filename, &a.Size, &a.LocalPath, &a.Transcription, &a.Status); err != nil {
			return nil, err
		}
		attachments = append(attachments, a)
	}

	return attachments, nil
}

// CreateCommand inserts a new command.
func (s *Store) CreateCommand(c *core.Command) error {
	_, err := s.db.Exec(`
		INSERT INTO commands (id, type, payload, status, error, created_at, updated_at)
		VALUES (?, ?, ?, ?, ?, ?, ?)
	`, c.ID, c.Type, c.Payload, c.Status, c.Error, c.CreatedAt, c.UpdatedAt)
	return err
}

// GetCommand retrieves a command by ID.
func (s *Store) GetCommand(id string) (*core.Command, error) {
	var c core.Command

	err := s.db.QueryRow(`
		SELECT id, type, payload, status, error, created_at, updated_at
		FROM commands WHERE id = ?
	`, id).Scan(&c.ID, &c.Type, &c.Payload, &c.Status, &c.Error, &c.CreatedAt, &c.UpdatedAt)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}

	return &c, nil
}

// UpdateCommandStatus updates a command's status and error.
func (s *Store) UpdateCommandStatus(id, status, errMsg string) error {
	_, err := s.db.Exec(`
		UPDATE commands SET status = ?, error = ?, updated_at = ? WHERE id = ?
	`, status, errMsg, time.Now(), id)
	return err
}

// Ping checks database connectivity.
func (s *Store) Ping() error {
	return s.db.Ping()
}