// Seat-durable goal state persistence (Q7b: survives /new, /resume, restarts).
// The state file lives beside the pi agent home: $PI_CODING_AGENT_DIR/goal-state.json
// for fleet seats, ~/.pi/agent/goal-state.json for operator sessions.
//
// NG-7 INCARNATION FENCING (Mercer F1, board T129): the seat-level file was
// ONE shared mutable object — two incarnations of a seat (marcie + marcie-2)
// inherited and rewrote each other's goal state on session_start. State is
// now FENCED per process-launch incarnation identity (mosaic-core
// lib/incarnation.ts — the same identity the R6 journal keys on; NOT
// PI_SESSION_ID, which is session identity):
//
//   <agentDir>/goal-state.<incarnationId>.json
//
// Migration (NG-7 remediation F4): an existing unfenced goal-state.json has
// an UNKNOWN OWNER — for the live canary case it is legacy AND ACTIVE (a
// previous incarnation's focus), and velma B1 forbids a fresh incarnation
// inheriting another incarnation's active focus. So the legacy file is
// QUARANTINED, never claimed: atomically renamed aside with its bytes
// preserved (goal-state.legacy.json, then .legacy.1.json, .legacy.2.json…),
// and the resolving incarnation starts FRESH. Nobody inherits an active
// focus; nobody loses the evidence.

import { existsSync, mkdirSync, readFileSync, renameSync, writeFileSync, unlinkSync } from "node:fs";
import { randomUUID } from "node:crypto";
import { dirname, join } from "node:path";
import { homedir } from "node:os";
import { initialState, type GoalState } from "./state.ts";
import { incarnationIdentity } from "../../mosaic-core/lib/incarnation.ts";

export const LEGACY_STATE_FILENAME = "goal-state.json";

/** Pi agent home for the current process (seat dir for fleet seats, ~/.pi/agent otherwise). */
export function agentStateDir(env: NodeJS.ProcessEnv = process.env): string {
  const dir = env.PI_CODING_AGENT_DIR;
  if (dir && dir.trim() !== "") return dir;
  return join(homedir(), ".pi", "agent");
}

export function stateFilePath(dir: string = agentStateDir()): string {
  return join(dir, LEGACY_STATE_FILENAME);
}

/** The incarnation-fenced state file for a given agent dir + incarnation. */
export function fencedStateFilePath(dir: string, incarnationId: string): string {
  return join(dir, `goal-state.${incarnationId}.json`);
}

export interface ResolveIO {
  existsSync(path: string): boolean;
  renameSync(from: string, to: string): void;
}

function defaultResolveIO(): ResolveIO {
  return { existsSync, renameSync };
}

/** First free quarantine slot for the unknown-owner legacy file. */
export function quarantinePath(dir: string, io: ResolveIO): string {
  const first = join(dir, "goal-state.legacy.json");
  if (!io.existsSync(first)) return first;
  for (let n = 1; ; n++) {
    const candidate = join(dir, `goal-state.legacy.${n}.json`);
    if (!io.existsSync(candidate)) return candidate;
  }
}

/**
 * Resolve the state path for THIS process incarnation, quarantining any
 * unknown-owner legacy state (bytes preserved; the resolver starts fresh).
 * Inject `incarnationId` and `io` for tests; production callers take the
 * defaults.
 */
export function resolveStatePath(
  dir: string = agentStateDir(),
  opts: { incarnationId?: string; io?: ResolveIO } = {},
): string {
  const io = opts.io ?? defaultResolveIO();
  const incarnationId = opts.incarnationId ?? incarnationIdentity();
  const fenced = fencedStateFilePath(dir, incarnationId);
  if (io.existsSync(fenced)) return fenced;
  const legacy = join(dir, LEGACY_STATE_FILENAME);
  if (io.existsSync(legacy)) {
    try {
      io.renameSync(legacy, quarantinePath(dir, io)); // atomic, bytes preserved
    } catch {
      // raced by a sibling incarnation or fs trouble: start fresh rather
      // than ever reading a file another incarnation may still rewrite
      return fenced;
    }
  }
  return fenced;
}

export function loadState(path: string = stateFilePath()): GoalState {
  try {
    const parsed = JSON.parse(readFileSync(path, "utf8")) as Partial<GoalState>;
    if (parsed?.version !== 1 || typeof parsed.text !== "string" || !parsed.status) {
      return initialState();
    }
    return normalize(parsed as GoalState);
  } catch {
    return initialState();
  }
}

export function saveState(state: GoalState, path: string = stateFilePath()): void {
  mkdirSync(dirname(path), { recursive: true });
  const temporary = `${path}.${randomUUID()}.tmp`;
  try {
    writeFileSync(temporary, JSON.stringify(state, null, 2) + "\n", { encoding: "utf8", flag: "wx", mode: 0o600 });
    renameSync(temporary, path);
  } finally {
    if (existsSync(temporary)) unlinkSync(temporary);
  }
}

function normalize(state: GoalState): GoalState {
  const defaults = initialState();
  const maxChecks =
    Number.isInteger(state.maxChecks) && state.maxChecks >= 1
      ? state.maxChecks
      : defaults.maxChecks;
  const checks = Number.isInteger(state.checks) && state.checks >= 0 ? state.checks : 0;
  const maxNoProgressReports =
    Number.isInteger(state.maxNoProgressReports) && state.maxNoProgressReports >= 1
      ? state.maxNoProgressReports
      : defaults.maxNoProgressReports;
  const noProgressReports =
    Number.isInteger(state.noProgressReports) && state.noProgressReports >= 0
      ? state.noProgressReports
      : 0;
  const normalized: GoalState = {
    ...defaults,
    ...state,
    maxChecks,
    checks,
    maxNoProgressReports,
    noProgressReports,
    workEventSinceReport: state.workEventSinceReport === true,
  };
  const outcome = state.lastOutcome;
  delete normalized.lastOutcome;
  if (state.status === "none" && outcome?.status === "complete" &&
      typeof outcome.text === "string" && outcome.text.length > 0 &&
      typeof outcome.evidence === "string" && outcome.evidence.length > 0 &&
      typeof outcome.at === "string" && Number.isFinite(Date.parse(outcome.at))) {
    normalized.lastOutcome = { text: outcome.text, status: "complete", evidence: outcome.evidence.slice(0, 1000), at: outcome.at };
  }
  if (!["active", "paused", "blocked", "none"].includes(state.status)) {
    normalized.status = "paused";
    normalized.pausedReason = "invalid persisted status; inspect before /goal resume";
  }
  if (typeof normalized.pausedReason !== "string") delete normalized.pausedReason;
  if (state.waitTimeoutSeconds !== undefined) {
    const timeoutValid = Number.isInteger(state.waitTimeoutSeconds) && state.waitTimeoutSeconds >= 10 && state.waitTimeoutSeconds <= 86400;
    const wait = state.activeWait;
    const validTime = (value: unknown): value is number => typeof value === "number" && Number.isSafeInteger(value) && value > 0 && value <= 8640000000000000;
    const deadlineValid = !wait || (validTime(wait.deadlineAt) && wait.deadlineAt <= Date.now() + 86400000);
    const flagsValid = [state.waitWakeUsed, wait?.wakeSent, wait?.wakeObserved].every(value => value === undefined || typeof value === "boolean");
    const dispatchValid = !wait?.wakeSent || (validTime(wait.wakeDispatchedAt) &&
      typeof wait.wakeRequestId === "string" && wait.wakeRequestId.length > 0 && state.waitWakeUsed === true);
    if (!timeoutValid || !deadlineValid || !dispatchValid || !flagsValid) {
      return { ...normalized, status: state.status === "none" ? "none" : "paused", pausedReason: "invalid persisted wait state; inspect before /goal resume" };
    }
  }
  return normalized;
}