package store

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

	"steward/internal/model"
)

func scanHistory(sc interface{ Scan(...any) error }) (*model.HistoryEntry, error) {
	e := &model.HistoryEntry{}
	var t, changes string
	var uid, revertOf, revertedBy sql.NullInt64
	if err := sc.Scan(&e.ID, &t, &uid, &e.Username, &e.Via, &e.Description, &changes, &revertOf, &revertedBy); err != nil {
		return nil, err
	}
	e.Time = parseTS(t)
	e.UserID, e.RevertOf, e.RevertedBy = uid.Int64, revertOf.Int64, revertedBy.Int64
	if err := json.Unmarshal([]byte(changes), &e.Changes); err != nil {
		return nil, err
	}
	return e, nil
}

const historyCols = `id, time, user_id, username, via, description, changes, revert_of, reverted_by`

// ListHistory lists entries, newest first; before > 0 pages back.
func (s *Store) ListHistory(ctx context.Context, limit int, before int64) ([]*model.HistoryEntry, error) {
	if limit <= 0 || limit > 500 {
		limit = 100
	}
	q := `SELECT ` + historyCols + ` FROM history`
	var args []any
	if before > 0 {
		q += ` WHERE id < ?`
		args = append(args, before)
	}
	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.HistoryEntry{}
	for rows.Next() {
		e, err := scanHistory(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, e)
	}
	return out, rows.Err()
}

// GetHistory loads one entry.
func (s *Store) GetHistory(ctx context.Context, id int64) (*model.HistoryEntry, error) {
	e, err := scanHistory(s.db.QueryRowContext(ctx, `SELECT `+historyCols+` FROM history WHERE id = ?`, id))
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	return e, err
}