package sqlite

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

	"github.com/google/uuid"

	"task/internal/ticket"
)

// TicketStore implements ticket.Store on SQLite.
type TicketStore struct {
	db *DB
}

// NewTicketStore returns a ticket store.
func NewTicketStore(db *DB) *TicketStore {
	return &TicketStore{db: db}
}

func scanTicket(scanner interface{ Scan(dest ...any) error }) (ticket.Ticket, error) {
	var t ticket.Ticket
	var created, updated, synced string
	var status string
	var number sql.NullInt64
	err := scanner.Scan(
		&t.ID, &t.Title, &t.Description, &status, &t.ProjectID,
		&created, &updated, &t.Source, &t.ExternalID, &t.ExternalURL, &synced,
		&number, &t.Key,
	)
	if err != nil {
		return ticket.Ticket{}, err
	}
	t.Status = ticket.Status(status)
	t.CreatedAt = parseTime(created)
	t.UpdatedAt = parseTime(updated)
	t.SyncedAt = parseTime(synced)
	if number.Valid {
		t.Number = int(number.Int64)
	}
	return t, nil
}

const ticketCols = `id, title, description, status, project_id, created_at, updated_at, source, external_id, external_url, synced_at, number, key`

// List returns tickets for a project.
func (s *TicketStore) List(projectID string) ([]ticket.Ticket, error) {
	rows, err := s.db.SQL.Query(`SELECT `+ticketCols+` FROM tickets WHERE project_id = ? ORDER BY updated_at DESC`, projectID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []ticket.Ticket
	for rows.Next() {
		t, err := scanTicket(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, t)
	}
	if out == nil {
		out = []ticket.Ticket{}
	}
	return out, rows.Err()
}

// Get finds a ticket by ID.
func (s *TicketStore) Get(id string) (ticket.Ticket, error) {
	row := s.db.SQL.QueryRow(`SELECT `+ticketCols+` FROM tickets WHERE id = ?`, id)
	t, err := scanTicket(row)
	if err == sql.ErrNoRows {
		return ticket.Ticket{}, fmt.Errorf("ticket %s: not found", id)
	}
	if err != nil {
		return ticket.Ticket{}, err
	}
	return t, nil
}

// Create inserts a ticket and assigns the next project key atomically.
func (s *TicketStore) Create(t ticket.Ticket) (ticket.Ticket, error) {
	if t.ProjectID == "" {
		return ticket.Ticket{}, fmt.Errorf("projectId is required")
	}
	if t.Title == "" {
		return ticket.Ticket{}, fmt.Errorf("title is required")
	}
	if t.ID == "" {
		t.ID = uuid.NewString()
	}
	if t.Status == "" {
		t.Status = ticket.StatusTodo
	}
	now := time.Now().UTC()
	if t.CreatedAt.IsZero() {
		t.CreatedAt = now
	}
	if t.UpdatedAt.IsZero() {
		t.UpdatedAt = now
	}

	tx, err := s.db.SQL.Begin()
	if err != nil {
		return ticket.Ticket{}, err
	}
	defer func() { _ = tx.Rollback() }()

	if t.Number == 0 || t.Key == "" {
		res, err := tx.Exec(`UPDATE projects SET ticket_seq = ticket_seq + 1 WHERE id = ?`, t.ProjectID)
		if err != nil {
			return ticket.Ticket{}, fmt.Errorf("create ticket: bump seq: %w", err)
		}
		n, _ := res.RowsAffected()
		if n == 0 {
			return ticket.Ticket{}, fmt.Errorf("create ticket: project %s not found", t.ProjectID)
		}
		var code string
		var seq int
		if err := tx.QueryRow(`SELECT code, ticket_seq FROM projects WHERE id = ?`, t.ProjectID).Scan(&code, &seq); err != nil {
			return ticket.Ticket{}, fmt.Errorf("create ticket: read seq: %w", err)
		}
		if code == "" {
			return ticket.Ticket{}, fmt.Errorf("create ticket: project %s has no code", t.ProjectID)
		}
		t.Number = seq
		t.Key = fmt.Sprintf("%s-%d", code, seq)
	}

	var number any
	if t.Number > 0 {
		number = t.Number
	}
	_, err = tx.Exec(`
		INSERT INTO tickets(`+ticketCols+`) VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?)`,
		t.ID, t.Title, t.Description, string(t.Status), t.ProjectID,
		formatTime(t.CreatedAt), formatTime(t.UpdatedAt), t.Source, t.ExternalID, t.ExternalURL, formatTime(t.SyncedAt),
		number, t.Key,
	)
	if err != nil {
		return ticket.Ticket{}, fmt.Errorf("create ticket: %w", err)
	}
	if err := tx.Commit(); err != nil {
		return ticket.Ticket{}, err
	}
	return t, nil
}

// Update replaces a ticket and bumps UpdatedAt. Number and Key are preserved from DB.
func (s *TicketStore) Update(t ticket.Ticket) error {
	if t.ID == "" || t.ProjectID == "" {
		return fmt.Errorf("id and projectId are required")
	}
	var created string
	var number sql.NullInt64
	var key string
	err := s.db.SQL.QueryRow(`SELECT created_at, number, key FROM tickets WHERE id = ? AND project_id = ?`, t.ID, t.ProjectID).
		Scan(&created, &number, &key)
	if err == sql.ErrNoRows {
		return fmt.Errorf("ticket %s: not found", t.ID)
	}
	if err != nil {
		return err
	}
	t.CreatedAt = parseTime(created)
	t.UpdatedAt = time.Now().UTC()
	if number.Valid {
		t.Number = int(number.Int64)
	}
	t.Key = key
	res, err := s.db.SQL.Exec(`
		UPDATE tickets SET title=?, description=?, status=?, project_id=?, created_at=?, updated_at=?,
			source=?, external_id=?, external_url=?, synced_at=?, number=?, key=?
		WHERE id=?`,
		t.Title, t.Description, string(t.Status), t.ProjectID, formatTime(t.CreatedAt), formatTime(t.UpdatedAt),
		t.Source, t.ExternalID, t.ExternalURL, formatTime(t.SyncedAt), nullInt(t.Number), t.Key, t.ID,
	)
	if err != nil {
		return err
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return fmt.Errorf("ticket %s: not found", t.ID)
	}
	return nil
}

func nullInt(n int) any {
	if n == 0 {
		return nil
	}
	return n
}

// MarkSynced sets SyncedAt = UpdatedAt without bumping UpdatedAt.
func (s *TicketStore) MarkSynced(id string) error {
	if id == "" {
		return fmt.Errorf("ticket id is required")
	}
	res, err := s.db.SQL.Exec(`UPDATE tickets SET synced_at = updated_at WHERE id = ?`, id)
	if err != nil {
		return err
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return fmt.Errorf("ticket %s: not found", id)
	}
	return nil
}

// Move relocates a ticket to another project and assigns a new key there.
func (s *TicketStore) Move(id, toProjectID string) (ticket.Ticket, error) {
	if id == "" {
		return ticket.Ticket{}, fmt.Errorf("ticket id is required")
	}
	if toProjectID == "" {
		return ticket.Ticket{}, fmt.Errorf("projectId is required")
	}

	tx, err := s.db.SQL.Begin()
	if err != nil {
		return ticket.Ticket{}, err
	}
	defer func() { _ = tx.Rollback() }()

	row := tx.QueryRow(`SELECT `+ticketCols+` FROM tickets WHERE id = ?`, id)
	t, err := scanTicket(row)
	if err == sql.ErrNoRows {
		return ticket.Ticket{}, fmt.Errorf("ticket %s: not found", id)
	}
	if err != nil {
		return ticket.Ticket{}, err
	}

	res, err := tx.Exec(`UPDATE projects SET ticket_seq = ticket_seq + 1 WHERE id = ?`, toProjectID)
	if err != nil {
		return ticket.Ticket{}, err
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return ticket.Ticket{}, fmt.Errorf("project %s: not found", toProjectID)
	}
	var code string
	var seq int
	if err := tx.QueryRow(`SELECT code, ticket_seq FROM projects WHERE id = ?`, toProjectID).Scan(&code, &seq); err != nil {
		return ticket.Ticket{}, err
	}
	t.ProjectID = toProjectID
	t.Number = seq
	t.Key = fmt.Sprintf("%s-%d", code, seq)
	t.UpdatedAt = time.Now().UTC()

	_, err = tx.Exec(`UPDATE tickets SET project_id=?, updated_at=?, number=?, key=? WHERE id=?`,
		toProjectID, formatTime(t.UpdatedAt), t.Number, t.Key, id)
	if err != nil {
		return ticket.Ticket{}, err
	}
	if err := tx.Commit(); err != nil {
		return ticket.Ticket{}, err
	}
	return t, nil
}

// Delete removes a ticket.
func (s *TicketStore) Delete(id string) error {
	res, err := s.db.SQL.Exec(`DELETE FROM tickets WHERE id = ?`, id)
	if err != nil {
		return err
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return fmt.Errorf("ticket %s: not found", id)
	}
	return nil
}