import { isTransientGithubFailure } from './github-errors.ts'
import { collectBranchHistory, ingestMissingFromList } from './ingest.ts'
import { refreshIgnoreIndex } from './ignore-rules.ts'
import { getRepoSettings, ingestSummary } from './storage.ts'

/**
 * Ingest missing mainline commits into package storage, oldest gaps first.
 * Use this for the initial fill and whenever the graph is missing history.
 *
 * @param input - Optional batch size, page cap, and whether to refresh ignore rules
 * @returns How many commits were stored and whether more remain. Transient
 *   GitHub/Cloudflare failures return `deferred: true` instead of throwing so
 *   the five-minute job can retry on the next tick. The ingest deadline is
 *   measured from the start of this call so a slow history listing cannot
 *   spend a fresh 60s after the 90s platform budget is already gone. Listing
 *   itself stops at two thirds of the budget (`listingComplete: false`) and
 *   every GitHub request carries a bounded timeout.
 *
 * @example
 * import backfill from 'kody:@kentcdodds/lineage/backfill'
 *
 * const progress = await backfill({ limit: 50 })
 */
export default async function backfill(
	input: {
		limit?: number
		maxPages?: number
		refreshIgnore?: boolean
		deadlineMs?: number
	} = {},
) {
	const startedAt = Date.now()
	const budgetMs = input.deadlineMs ?? 70_000
	// Leave at least a third of the budget for ingest after listing.
	const listingDeadline = startedAt + Math.round(budgetMs * (2 / 3))
	if (input.refreshIgnore) {
		await refreshIgnoreIndex()
	}
	const repo = await getRepoSettings()
	let history
	try {
		history = await collectBranchHistory({
			maxPages: input.maxPages ?? 40,
			deadline: listingDeadline,
		})
	} catch (error) {
		if (!isTransientGithubFailure(error)) throw error
		const summary = await ingestSummary()
		return {
			ok: true,
			deferred: true,
			reason: error instanceof Error ? error.message : String(error),
			repo,
			listed: 0,
			ingested: 0,
			alreadyStored: 0,
			remaining: 1,
			errors: [],
			shas: [],
			done: false,
			ingest: summary,
		}
	}
	const chronological = [...history.items].reverse()
	const result = await ingestMissingFromList(chronological, {
		limit: input.limit ?? 80,
		deadlineMs: Math.max(0, startedAt + budgetMs - Date.now()),
	})
	const summary = await ingestSummary()
	return {
		ok: true,
		deferred: false,
		repo,
		listed: history.items.length,
		listingComplete: history.complete,
		...result,
		done: history.complete && result.remaining === 0 && result.errors.length === 0,
		ingest: summary,
	}
}