// SPEC: PJ2026-01060703 CI/CD branch follower controller scheduling.
// Responsibility: keep source discovery and active closeout ahead of unrelated followers.

import type { FollowerSpec, FollowerState, ParsedOptions } from "./cicd-types";

const ACTIVE_PHASES = new Set(["PendingTrigger", "Triggering", "Superseded"]);
const CLOSEOUT_PHASES = new Set(["ClosingOut"]);
const SOURCE_DISCOVERY_PHASES = new Set(["Observed", "Noop", "Succeeded", "Failed", "Blocked", "Skipped"]);

export function orderFollowersForControllerCloseout(
  followers: FollowerSpec[],
  stateByFollower: Record<string, Record<string, unknown>>,
): FollowerSpec[] {
  return followers
    .map((follower, index) => ({ follower, index, priority: followerPriority(stateByFollower[follower.id]) }))
    .sort((left, right) => left.priority - right.priority || left.index - right.index)
    .map((item) => item.follower);
}

export function shouldYieldAfterAutomaticTrigger(options: ParsedOptions, state: FollowerState): boolean {
  if (!options.inCluster || !options.confirm || options.wait || options.dryRun) return false;
  return state.phase === "Triggering" && state.inFlightJob !== null;
}

function followerPriority(state: Record<string, unknown> | undefined): number {
  if (state === undefined) return 1;
  const phase = typeof state.phase === "string" ? state.phase : null;
  if (typeof state.inFlightJob === "string" && state.inFlightJob.trim() !== "") return 0;
  if (phase !== null && ACTIVE_PHASES.has(phase)) return 0;
  if (isSourceDiscoveryCandidate(phase)) return 1;
  if (hasStoredSourceTargetMismatch(state)) return 2;
  if (hasUnfinishedObservedSource(state)) return 2;
  if (phase !== null && CLOSEOUT_PHASES.has(phase)) return 2;
  return 3;
}

function isSourceDiscoveryCandidate(phase: string | null): boolean {
  return phase === null || SOURCE_DISCOVERY_PHASES.has(phase);
}

function hasStoredSourceTargetMismatch(state: Record<string, unknown>): boolean {
  const observedSha = nestedString(state, "source", "observedSha");
  const targetSha = nestedString(state, "target", "targetSha");
  return observedSha !== null && targetSha !== null && observedSha !== targetSha;
}

function hasUnfinishedObservedSource(state: Record<string, unknown>): boolean {
  const observedSha = nestedString(state, "source", "observedSha");
  const lastSucceededSha = typeof state.lastSucceededSha === "string" ? state.lastSucceededSha : null;
  if (observedSha === null) return false;
  return lastSucceededSha === null || lastSucceededSha !== observedSha;
}

function nestedString(source: Record<string, unknown>, parentKey: string, childKey: string): string | null {
  const parent = source[parentKey];
  if (parent === null || typeof parent !== "object" || Array.isArray(parent)) return null;
  const value = (parent as Record<string, unknown>)[childKey];
  return typeof value === "string" && value.trim() !== "" ? value : null;
}