package store

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"time"

	"housecarl/internal/model"
)

const changesetCols = `id, user_id, username, via, description, status, ops, created_at, updated_at, history_id`

func scanChangeset(sc interface{ Scan(...any) error }) (*model.Changeset, error) {
	cs := &model.Changeset{}
	var uid, hid sql.NullInt64
	var ops, created, updated string
	if err := sc.Scan(&cs.ID, &uid, &cs.Username, &cs.Via, &cs.Description, &cs.Status, &ops, &created, &updated, &hid); err != nil {
		return nil, err
	}
	cs.UserID, cs.HistoryID = uid.Int64, hid.Int64
	cs.CreatedAt, cs.UpdatedAt = parseTS(created), parseTS(updated)
	if err := json.Unmarshal([]byte(ops), &cs.Ops); err != nil {
		return nil, err
	}
	if cs.Ops == nil {
		cs.Ops = []model.Op{}
	}
	return cs, nil
}

// CreateChangeset saves a new changeset and sets its ID.
func (s *Store) CreateChangeset(ctx context.Context, cs *model.Changeset) error {
	now := time.Now()
	cs.CreatedAt, cs.UpdatedAt = now, now
	if cs.Ops == nil {
		cs.Ops = []model.Op{}
	}
	ops, _ := json.Marshal(cs.Ops)
	res, err := s.db.ExecContext(ctx, `INSERT INTO changesets (user_id, username, via, description, status, ops, created_at, updated_at)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?)`, nullID(cs.UserID), cs.Username, cs.Via, cs.Description, cs.Status, string(ops), ts(now), ts(now))
	if err != nil {
		return err
	}
	cs.ID, err = res.LastInsertId()
	return err
}

// GetChangeset loads one changeset.
func (s *Store) GetChangeset(ctx context.Context, id int64) (*model.Changeset, error) {
	cs, err := scanChangeset(s.db.QueryRowContext(ctx, `SELECT `+changesetCols+` FROM changesets WHERE id = ?`, id))
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	return cs, err
}

// ListChangesets lists changesets, newest first: of a status ("" any),
// and of a user (0 anyone's).
func (s *Store) ListChangesets(ctx context.Context, status string, userID int64, limit int) ([]*model.Changeset, error) {
	if limit <= 0 || limit > 500 {
		limit = 100
	}
	q := `SELECT ` + changesetCols + ` FROM changesets WHERE 1=1`
	var args []any
	if status != "" {
		q += ` AND status = ?`
		args = append(args, status)
	}
	if userID != 0 {
		q += ` AND user_id = ?`
		args = append(args, userID)
	}
	q += ` ORDER BY id DESC LIMIT ?`
	args = append(args, limit)
	rows, err := s.db.QueryContext(ctx, q, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := []*model.Changeset{}
	for rows.Next() {
		cs, err := scanChangeset(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, cs)
	}
	return out, rows.Err()
}

// UpdateChangeset saves a changeset's description, status, operations and
// history entry.
func (s *Store) UpdateChangeset(ctx context.Context, cs *model.Changeset) error {
	cs.UpdatedAt = time.Now()
	ops, _ := json.Marshal(cs.Ops)
	res, err := s.db.ExecContext(ctx, `UPDATE changesets SET description = ?, status = ?, ops = ?, updated_at = ?, history_id = ? WHERE id = ?`,
		cs.Description, cs.Status, string(ops), ts(cs.UpdatedAt), nullID(cs.HistoryID), cs.ID)
	if err != nil {
		return err
	}
	if n, _ := res.RowsAffected(); n == 0 {
		return ErrNotFound
	}
	return nil
}

func nullID(id int64) any {
	if id == 0 {
		return nil
	}
	return id
}