import { accountHistory } from '../../investment-sync-plan';
import { confirmedOperationRanges, type OperationCoverage,
  type OperationInterval,
  operationIntervalsOverlap,
  operationsSyncPriority,
  planOperationRead,
  uncoveredOperationIntervals } from './operations-sync-plan';

const UNKNOWN_AS_OF_MS = 0;

type WorkState = {
  errorCode: null | string;
  id: string;
  intervals: OperationInterval[];
  priority: number;
  state: string;
};

type CoverageAccount = { accountId: string; openedOn: null | string };

// Pure derivation of the ledger read view: what was requested, what is
// confirmed, what is missing, and which sync work is currently relevant.
export function deriveReadCoverage(input: {
  accounts: CoverageAccount[];
  connectionMembershipAt: Date | null;
  coverage: OperationCoverage[];
  from: Date;
  instrumentUid?: string;
  movingEnd: boolean;
  now: Date;
  to: Date;
  work: WorkState[];
}) {
  const targets = input.accounts.flatMap((account) =>
    input.from < input.to
      ? [
          {
            accountId: account.accountId,
            from: input.from,
            to: input.to,
            instrumentUid: input.instrumentUid,
          },
        ]
      : [],
  );
  const plan = planOperationRead(targets, input.coverage, input.now, {
    movingEnd: input.movingEnd,
  });
  const confirmed = confirmedOperationRanges(plan.intervals, input.coverage);
  const missing = uncoveredOperationIntervals(
    plan.intervals,
    confirmed.map((range) => ({
      ...range,
      instrumentUid: input.instrumentUid,
    })),
  );
  const available = Boolean(input.connectionMembershipAt);
  const complete = available && !missing.length;
  const relevant = input.work.filter((work) =>
    work.intervals.some((interval) =>
      targets.some((target) => operationIntervalsOverlap(interval, target)),
    ),
  );
  const work =
    relevant.find((work) => work.state === 'running') ??
    relevant.find((work) => work.state === 'failed') ??
    null;
  const sources = input.coverage.filter((row) =>
    targets.some(
      (target) =>
        operationIntervalsOverlap(row, target) &&
        (!row.instrumentUid || row.instrumentUid === target.instrumentUid),
    ),
  );
  const lastSuccessfulAt =
    sources
      .map((row) => row.fetchedAt)
      .sort((a, b) => a.valueOf() - b.valueOf())[0] ??
      (complete ? input.connectionMembershipAt : null) ??
      null;
  const history = planOperationRead(
    accountHistory(input.accounts, input.now),
    input.coverage,
    input.now,
    { movingEnd: true },
  );
  const knownBoundary = input.accounts.every(
    (account) => account.openedOn !== null,
  );
  return {
    targets,
    plan,
    confirmed,
    missing,
    available,
    complete,
    work,
    lastSuccessfulAt,
    history,
    knownBoundary,
  };
}

export function coverageAsOf(
  plan: ReturnType<typeof planOperationRead>,
  accountIds: string[],
): null | string {
  if (
    accountIds.length &&
    accountIds.every((accountId) =>
      plan.intervals.some(
        (interval) =>
          interval.accountId === accountId && interval.asOf,
      ),
    )
  ) {
    return new Date(
      Math.min(
        ...accountIds.map((accountId) =>
          Math.max(
            ...plan.intervals
              .filter((interval) => interval.accountId === accountId)
              .map((interval) => interval.asOf?.valueOf() ?? UNKNOWN_AS_OF_MS),
          ),
        ),
      ),
    ).toISOString();
  }
  return null;
}

export function historyState(
  knownBoundary: boolean,
  history: ReturnType<typeof planOperationRead>,
  work: WorkState[],
  coverageCount: number,
): 'complete' | 'failed' | 'loading' | 'missing' | 'partial' {
  if (
    work.some(
      (work) => work.state === 'running' && work.priority > operationsSyncPriority.screen,
    )
  ) {
    return 'loading';
  }
  if (
    work.some(
      (work) => work.state === 'failed' && work.priority > operationsSyncPriority.screen,
    )
  ) {
    return 'failed';
  }
  if (
    knownBoundary &&
    history.intervals.every(
      (interval) => interval.availability === 'complete',
    )
  ) {
    return 'complete';
  }
  return coverageCount ? 'partial' : 'missing';
}

export function serializeRange(range: { accountId: string; from: Date; to: Date }) {
  return { accountId: range.accountId, from: range.from.toISOString(), to: range.to.toISOString() };
}