package core

import "time"

// stampLayout is the one canonical on-disk timestamp format.
//
// It is deliberately fixed-width: exactly three fractional digits and a literal
// trailing Z. The columns it feeds are compared as TEXT by SQLite, so
// lexicographic order MUST equal chronological order for every ORDER BY, MAX,
// and `run_after <= ?` / `expires_at < ?` comparison to be correct.
//
// time.RFC3339Nano cannot be used for writes because it trims trailing zeros,
// which makes the fraction width vary: ".5Z" sorts after ".55Z" as a string
// even though 500ms is earlier than 550ms. That is wrong even when a column is
// written 100% by Go; it is not a cross-format problem.
//
// The layout also matches SQLite's own default
// strftime('%Y-%m-%dT%H:%M:%fZ','now'), which emits exactly three fractional
// digits and a Z. Matching it byte-for-byte means rows written by Go and rows
// written by a column DEFAULT compare correctly against each other.
const stampLayout = "2006-01-02T15:04:05.000Z"

// Stamp formats t as the canonical database timestamp.
func Stamp(t time.Time) string {
	return t.UTC().Format(stampLayout)
}

// Now returns the current time as the canonical database timestamp.
func Now() string {
	return Stamp(time.Now())
}