// Package messagesvc
// Path: /internal/platform/services/messages
// File: service.go

package messagesvc

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"time"

	"synlotto-website/internal/logging"

	domain "synlotto-website/internal/domain/messages"

	"github.com/go-sql-driver/mysql"
)

// Service implements domain.Service.
type Service struct {
	DB      *sql.DB
	Dialect string // "postgres", "mysql", "sqlite"
	Now     func() time.Time
	Timeout time.Duration
}

func New(db *sql.DB, opts ...func(*Service)) *Service {
	s := &Service{
		DB:      db,
		Dialect: "mysql", // default; works with LastInsertId
		Now:     time.Now,
		Timeout: 5 * time.Second,
	}
	for _, opt := range opts {
		opt(s)
	}
	return s
}

// Ensure *Service satisfies the domain interface.
var _ domain.MessageService = (*Service)(nil)

func (s *Service) ListInbox(userID int64) ([]domain.Message, error) {
	ctx, cancel := context.WithTimeout(context.Background(), s.Timeout)
	defer cancel()

	q := `
		SELECT id, senderId, recipientId, subject, body, is_read, is_archived, created_at
		FROM user_messages
		WHERE recipientId = ? AND is_archived = FALSE
		ORDER BY created_at DESC`
	q = s.bind(q)

	rows, err := s.DB.QueryContext(ctx, q, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []domain.Message
	for rows.Next() {
		var m domain.Message
		if err := rows.Scan(&m.ID, &m.SenderId, &m.RecipientId, &m.Subject, &m.Body, &m.IsRead, &m.IsArchived, &m.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, m)
	}

	return out, rows.Err()
}

func (s *Service) ListArchived(userID int64) ([]domain.Message, error) {
	ctx, cancel := context.WithTimeout(context.Background(), s.Timeout)
	defer cancel()

	q := `
		SELECT id, senderId, recipientId, subject, body,
		       is_read, is_archived, created_at, archived_at
		FROM user_messages
		WHERE recipientId = ? AND is_archived = TRUE
		ORDER BY created_at DESC`
	q = s.bind(q)

	rows, err := s.DB.QueryContext(ctx, q, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []domain.Message
	for rows.Next() {
		var m domain.Message
		var archived sql.NullTime

		if err := rows.Scan(
			&m.ID,
			&m.SenderId,
			&m.RecipientId,
			&m.Subject,
			&m.Body,
			&m.IsRead,
			&m.IsArchived,
			&m.CreatedAt,
			&archived,
		); err != nil {
			return nil, err
		}

		if archived.Valid {
			t := archived.Time
			m.ArchivedAt = &t
		} else {
			m.ArchivedAt = nil
		}

		out = append(out, m)
	}

	return out, rows.Err()
}

func (s *Service) GetByID(userID, id int64) (*domain.Message, error) {
	ctx, cancel := context.WithTimeout(context.Background(), s.Timeout)
	defer cancel()

	q := `
		SELECT id, senderId, recipientId, subject, body, is_read, is_archived, created_at
		FROM user_messages
		WHERE recipientId = ? AND id = ?`
	q = s.bind(q)

	var m domain.Message
	err := s.DB.QueryRowContext(ctx, q, userID, id).
		Scan(&m.ID, &m.SenderId, &m.RecipientId, &m.Subject, &m.Body, &m.IsRead, &m.IsArchived, &m.CreatedAt)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	return &m, nil
}

func (s *Service) Create(senderID int64, in domain.CreateMessageInput) (int64, error) {
	ctx, cancel := context.WithTimeout(context.Background(), s.Timeout)
	defer cancel()

	// ✅ make sure this matches your current table/column names
	const q = `
		INSERT INTO user_messages
			(senderId, recipientId, subject, body, is_read, is_archived, created_at)
		VALUES
			(?, ?, ?, ?, 0, 0, CURRENT_TIMESTAMP)
	`

	// 👀 Log the SQL and arguments (truncate body in logs if you prefer)
	logging.Info("🧪 SQL Exec: %s | args: senderId=%d recipientId=%d subject=%q body_len=%d", compactSQL(q), senderID, in.RecipientID, in.Subject, len(in.Body))

	res, err := s.DB.ExecContext(ctx, q, senderID, in.RecipientID, in.Subject, in.Body)
	if err != nil {
		// Surface MySQL code/message (very helpful for FK #1452 etc.)
		var me *mysql.MySQLError
		if errors.As(err, &me) {
			wrapped := fmt.Errorf("insert user_messages: mysql #%d %s | args(senderId=%d, recipientId=%d, subject=%q, body_len=%d)",
				me.Number, me.Message, senderID, in.RecipientID, in.Subject, len(in.Body))
			logging.Info("❌ %v", wrapped)
			return 0, wrapped
		}
		wrapped := fmt.Errorf("insert user_messages: %w | args(senderId=%d, recipientId=%d, subject=%q, body_len=%d)",
			err, senderID, in.RecipientID, in.Subject, len(in.Body))
		logging.Info("❌ %v", wrapped)
		return 0, wrapped
	}

	id, err := res.LastInsertId()
	if err != nil {
		wrapped := fmt.Errorf("lastInsertId user_messages: %w", err)
		logging.Info("❌ %v", wrapped)
		return 0, wrapped
	}

	logging.Info("✅ Inserted message id=%d", id)
	return id, nil
}

func compactSQL(s string) string {
	out := make([]rune, 0, len(s))
	space := false
	for _, r := range s {
		if r == '\n' || r == '\t' || r == '\r' || r == ' ' {
			if !space {
				out = append(out, ' ')
				space = true
			}
			continue
		}
		space = false
		out = append(out, r)
	}
	return string(out)
}

func (s *Service) bind(q string) string {
	if s.Dialect != "postgres" {
		return q
	}
	n := 0
	out := make([]byte, 0, len(q)+8)
	for i := 0; i < len(q); i++ {
		if q[i] == '?' {
			n++
			out = append(out, '$')
			out = append(out, []byte(intToStr(n))...)
			continue
		}
		out = append(out, q[i])
	}
	return string(out)
}

func (s *Service) Archive(userID, id int64) error {
	ctx, cancel := context.WithTimeout(context.Background(), s.Timeout)
	defer cancel()

	q := `
        UPDATE user_messages
        SET is_archived = 1, archived_at = CURRENT_TIMESTAMP
        WHERE id = ? AND recipientId = ?
    `
	q = s.bind(q)

	res, err := s.DB.ExecContext(ctx, q, id, userID)
	if err != nil {
		return err
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return sql.ErrNoRows
	}
	return nil
}

func intToStr(n int) string {
	if n == 0 {
		return "0"
	}
	var b [12]byte
	i := len(b)
	for n > 0 {
		i--
		b[i] = byte('0' + n%10)
		n /= 10
	}
	return string(b[i:])
}

func (s *Service) Unarchive(userID, id int64) error {
	ctx, cancel := context.WithTimeout(context.Background(), s.Timeout)
	defer cancel()

	q := `
        UPDATE user_messages
        SET is_archived = 0, archived_at = NULL
        WHERE id = ? AND recipientId = ?
    `
	q = s.bind(q)

	res, err := s.DB.ExecContext(ctx, q, id, userID)
	if err != nil {
		return err
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return sql.ErrNoRows
	}
	return nil
}