// Package sqliteutil holds small helpers shared by the SQLite repositories:
// timestamp conversion and dynamic IN-lists.
package sqliteutil

import (
	"database/sql"
	"strconv"
	"strings"
	"time"
)

// TimeLayout matches the SQLite column defaults produced by strftime with %f.
const TimeLayout = "2006-01-02T15:04:05.000Z"

// FormatTime renders a time in the canonical TEXT format used by the schema.
func FormatTime(t time.Time) string { return t.UTC().Format(TimeLayout) }

// ParseTime parses a canonical timestamp, tolerating the RFC3339 variants the
// driver may return. An empty or unparseable value yields the zero time.
func ParseTime(s string) time.Time {
	if s == "" {
		return time.Time{}
	}
	if t, err := time.Parse(TimeLayout, s); err == nil {
		return t
	}
	if t, err := time.Parse(time.RFC3339Nano, s); err == nil {
		return t
	}
	return time.Time{}
}

// ParseNullTime converts a nullable TEXT timestamp into *time.Time.
func ParseNullTime(ns sql.NullString) *time.Time {
	if !ns.Valid || ns.String == "" {
		return nil
	}
	t := ParseTime(ns.String)
	return &t
}

// Placeholders returns an IN-list placeholder group of n items starting at
// index start, e.g. Placeholders(3, 2) -> "$3,$4".
func Placeholders(start, n int) string {
	parts := make([]string, n)
	for i := 0; i < n; i++ {
		parts[i] = "$" + strconv.Itoa(start+i)
	}
	return strings.Join(parts, ",")
}