import { mkdir, readFile, rename, writeFile } from "node:fs/promises";
import { dirname, join } from "node:path";
import os from "node:os";

const MAX_OUTBOX_RECORDS = 500;
const MAX_APP_LOG_RECORDS = 120;
const RETRYABLE_STATUS_CODES = new Set([408, 409, 425, 429, 500, 502, 503, 504]);
const outboxWriteQueues = new Map();

function reliableOutboxPriority(record) {
  switch (record?.kind) {
    case "task.complete":
      return 0;
    case "task.progress":
      return 10;
    case "app.log":
      return 30;
    default:
      return 20;
  }
}

function recordCreatedMs(record) {
  const value = Date.parse(record?.createdAt || "");
  return Number.isFinite(value) ? value : 0;
}

function parseRecordBody(record) {
  if (!record || record.body == null) {
    return {};
  }
  if (typeof record.body === "object") {
    return record.body;
  }
  if (typeof record.body !== "string") {
    return {};
  }
  try {
    const parsed = JSON.parse(record.body);
    return parsed && typeof parsed === "object" ? parsed : {};
  } catch {
    return {};
  }
}

function taskProgressCoalescingKey(record) {
  if (record?.kind !== "task.progress") {
    return "";
  }
  const body = parseRecordBody(record);
  const taskId = typeof body.taskId === "string" ? body.taskId.trim() : "";
  if (taskId) {
    return taskId;
  }
  const url = typeof record.url === "string" ? record.url : "";
  const match = url.match(/\/master-agent\/tasks\/([^/]+)\/progress(?:\?|$)/);
  return match ? decodeURIComponent(match[1]) : "";
}

function taskCompletionCoalescingKey(record) {
  if (record?.kind !== "task.complete") {
    return "";
  }
  const body = parseRecordBody(record);
  const taskId = typeof body.taskId === "string" ? body.taskId.trim() : "";
  if (taskId) {
    return taskId;
  }
  const url = typeof record.url === "string" ? record.url : "";
  const match = url.match(/\/master-agent\/tasks\/([^/]+)\/complete(?:\?|$)/);
  return match ? decodeURIComponent(match[1]) : "";
}

function appLogCoalescingKey(record) {
  if (record?.kind !== "app.log") {
    return "";
  }
  const body = parseRecordBody(record);
  const category = typeof body.category === "string" ? body.category.trim() : "";
  const message = typeof body.message === "string" ? body.message.trim() : "";
  if (!category && !message) {
    return "";
  }
  const projectId = typeof body.projectId === "string" ? body.projectId.trim() : "";
  return [record.url || "", projectId, category, message].join("|");
}

function orderReliableOutboxRecordsForReplay(records) {
  return [...records].sort((left, right) => {
    const priorityDiff = reliableOutboxPriority(left) - reliableOutboxPriority(right);
    if (priorityDiff !== 0) return priorityDiff;
    return recordCreatedMs(left) - recordCreatedMs(right);
  });
}

function compactReliableOutboxRecords(records) {
  const active = records.filter((record) => record && record.id && record.status !== "sent");
  const completionTaskKeys = new Set(
    active.map(taskCompletionCoalescingKey).filter(Boolean),
  );
  const progressByTask = new Map();
  const retained = [];
  for (const record of active) {
    const progressKey = taskProgressCoalescingKey(record);
    if (!progressKey) {
      retained.push(record);
      continue;
    }
    if (completionTaskKeys.has(progressKey)) {
      continue;
    }
    const previous = progressByTask.get(progressKey);
    if (!previous || recordCreatedMs(record) >= recordCreatedMs(previous)) {
      progressByTask.set(progressKey, record);
    }
  }
  const keyedAppLogs = new Map();
  const unkeyedAppLogs = [];
  for (const record of retained.filter((item) => item.kind === "app.log")) {
    const appLogKey = appLogCoalescingKey(record);
    if (!appLogKey) {
      unkeyedAppLogs.push(record);
      continue;
    }
    const previous = keyedAppLogs.get(appLogKey);
    if (!previous || recordCreatedMs(record) >= recordCreatedMs(previous)) {
      keyedAppLogs.set(appLogKey, record);
    }
  }
  const appLogs = [...keyedAppLogs.values(), ...unkeyedAppLogs]
    .sort((left, right) => recordCreatedMs(right) - recordCreatedMs(left))
    .slice(0, MAX_APP_LOG_RECORDS);
  const compacted = [
    ...retained.filter((record) => record.kind !== "app.log"),
    ...progressByTask.values(),
    ...appLogs,
  ];
  if (compacted.length <= MAX_OUTBOX_RECORDS) {
    return compacted.sort((left, right) => recordCreatedMs(left) - recordCreatedMs(right));
  }
  const taskCompletions = compacted.filter((record) => record.kind === "task.complete");
  const remainingBudget = Math.max(0, MAX_OUTBOX_RECORDS - taskCompletions.length);
  const otherRecords = compacted
    .filter((record) => record.kind !== "task.complete")
    .sort((left, right) => {
      const priorityDiff = reliableOutboxPriority(left) - reliableOutboxPriority(right);
      if (priorityDiff !== 0) return priorityDiff;
      return recordCreatedMs(right) - recordCreatedMs(left);
    })
    .slice(0, remainingBudget);
  return [...taskCompletions, ...otherRecords].sort(
    (left, right) => recordCreatedMs(left) - recordCreatedMs(right),
  );
}

function normalizeTimeoutMs(value, fallback = 5_000) {
  const numeric = Number(value);
  if (!Number.isFinite(numeric) || numeric <= 0) {
    return fallback;
  }
  return Math.max(50, Math.min(60_000, Math.round(numeric)));
}

function normalizeDurationBudgetMs(value) {
  const numeric = Number(value);
  if (!Number.isFinite(numeric) || numeric <= 0) {
    return 0;
  }
  return Math.max(50, Math.min(60_000, Math.round(numeric)));
}

function nowIso() {
  return new Date().toISOString();
}

function randomId(prefix) {
  return `${prefix}-${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 10)}`;
}

export function resolveReliableOutboxPath(config = {}) {
  if (config.reliableOutboxPath) {
    return String(config.reliableOutboxPath);
  }
  return join(os.homedir(), ".boss-agent", `${config.deviceId || "device"}-outbox.json`);
}

async function readOutboxRecords(outboxPath) {
  try {
    const parsed = JSON.parse(await readFile(outboxPath, "utf8"));
    return Array.isArray(parsed?.records) ? parsed.records : [];
  } catch {
    return [];
  }
}

async function writeOutboxRecords(outboxPath, records) {
  await mkdir(dirname(outboxPath), { recursive: true });
  const compacted = compactReliableOutboxRecords(records);
  const tmpPath = `${outboxPath}.${process.pid}.${Date.now()}.tmp`;
  await writeFile(
    tmpPath,
    JSON.stringify({ version: 1, updatedAt: nowIso(), records: compacted }, null, 2),
  );
  await rename(tmpPath, outboxPath);
}

async function mutateOutboxRecords(outboxPath, mutator) {
  const run = async () => {
    const records = await readOutboxRecords(outboxPath);
    const result = await mutator(records);
    await writeOutboxRecords(outboxPath, result.records);
    return result.value;
  };
  const previous = outboxWriteQueues.get(outboxPath) || Promise.resolve();
  const next = previous.then(run, run);
  outboxWriteQueues.set(outboxPath, next.catch(() => null));
  return await next;
}

export async function appendReliableOutboxRecord(outboxPath, input) {
  const record = {
    id: input.id || randomId(input.kind || "outbox"),
    kind: input.kind,
    url: input.url,
    method: input.method || "POST",
    headers: input.headers || {},
    body: input.body,
    requestTimeoutMs: input.requestTimeoutMs,
    status: "pending",
    attemptCount: 0,
    createdAt: nowIso(),
    lastAttemptAt: undefined,
    lastError: undefined,
  };
  return await mutateOutboxRecords(outboxPath, async (records) => ({
    records: [...records, record],
    value: record,
  }));
}

export async function markReliableOutboxRecordSent(outboxPath, recordId) {
  await mutateOutboxRecords(outboxPath, async (records) => ({
    records: records.filter((record) => record.id !== recordId),
    value: undefined,
  }));
}

function shouldRetry(status) {
  if (!status) return true;
  return RETRYABLE_STATUS_CODES.has(status);
}

async function updateReliableOutboxRecordFailure(outboxPath, recordId, detail) {
  await mutateOutboxRecords(outboxPath, async (records) => ({
    records: records.map((record) => {
      if (record.id !== recordId) return record;
      return {
        ...record,
        attemptCount: Number(record.attemptCount || 0) + 1,
        lastAttemptAt: nowIso(),
        lastError: String(detail || "OUTBOX_SEND_FAILED").slice(0, 240),
      };
    }),
    value: undefined,
  }));
}

export async function sendReliableOutboxRecord(record, options = {}) {
  const timeoutMs = normalizeTimeoutMs(options.requestTimeoutMs ?? record.requestTimeoutMs);
  const controller = new AbortController();
  const timeout = setTimeout(() => {
    controller.abort(new Error("RELIABLE_OUTBOX_SEND_TIMEOUT"));
  }, timeoutMs);
  try {
    const response = await fetch(record.url, {
      method: record.method || "POST",
      headers: record.headers || {},
      body: typeof record.body === "string" ? record.body : JSON.stringify(record.body ?? {}),
      signal: controller.signal,
    });
    const body = await response.text();
    return {
      ok: response.ok,
      retryable: !response.ok && shouldRetry(response.status),
      status: response.status,
      body,
    };
  } catch (error) {
    if (controller.signal.aborted) {
      throw new Error("RELIABLE_OUTBOX_SEND_TIMEOUT");
    }
    throw error;
  } finally {
    clearTimeout(timeout);
  }
}

export async function postThroughReliableOutbox(config, recordInput) {
  if (config.reliableOutboxEnabled === false) {
    return await sendReliableOutboxRecord({
      ...recordInput,
      id: recordInput.id || randomId(recordInput.kind || "direct"),
      requestTimeoutMs: recordInput.requestTimeoutMs ?? config.reliableOutboxRequestTimeoutMs,
    });
  }

  const outboxPath = resolveReliableOutboxPath(config);
  const record = await appendReliableOutboxRecord(outboxPath, {
    ...recordInput,
    requestTimeoutMs: recordInput.requestTimeoutMs ?? config.reliableOutboxRequestTimeoutMs,
  });
  try {
    const result = await sendReliableOutboxRecord(record, {
      requestTimeoutMs: record.requestTimeoutMs ?? config.reliableOutboxRequestTimeoutMs,
    });
    if (result.ok || !result.retryable) {
      await markReliableOutboxRecordSent(outboxPath, record.id);
    } else {
      await updateReliableOutboxRecordFailure(outboxPath, record.id, result.body);
    }
    return result;
  } catch (error) {
    await updateReliableOutboxRecordFailure(
      outboxPath,
      record.id,
      error instanceof Error ? error.message : String(error),
    );
    return {
      ok: false,
      retryable: true,
      status: 0,
      body: error instanceof Error ? error.message : String(error),
    };
  }
}

export async function replayReliableOutbox(config, options = {}) {
  if (config.reliableOutboxEnabled === false) {
    return { attempted: 0, sent: 0, retained: 0 };
  }
  const outboxPath = resolveReliableOutboxPath(config);
  const records = (await readOutboxRecords(outboxPath)).filter(
    (record) => record?.status !== "sent",
  );
  const limit = Math.max(1, Math.min(Number(options.limit || 50), 100));
  const startedAt = Date.now();
  const maxDurationMs = normalizeDurationBudgetMs(options.maxDurationMs ?? config.reliableOutboxReplayBudgetMs);
  const requestTimeoutMs = options.requestTimeoutMs ?? config.reliableOutboxRequestTimeoutMs;
  let attempted = 0;
  let sent = 0;
  let stoppedByBudget = false;
  for (const record of orderReliableOutboxRecordsForReplay(records).slice(0, limit)) {
    if (maxDurationMs > 0 && Date.now() - startedAt >= maxDurationMs) {
      stoppedByBudget = true;
      break;
    }
    attempted += 1;
    try {
      const result = await sendReliableOutboxRecord(record, {
        requestTimeoutMs: record.requestTimeoutMs ?? requestTimeoutMs,
      });
      if (result.ok || !result.retryable) {
        await markReliableOutboxRecordSent(outboxPath, record.id);
        sent += 1;
      } else {
        await updateReliableOutboxRecordFailure(outboxPath, record.id, result.body);
      }
    } catch (error) {
      await updateReliableOutboxRecordFailure(
        outboxPath,
        record.id,
        error instanceof Error ? error.message : String(error),
      );
    }
  }
  const retained = (await readOutboxRecords(outboxPath)).length;
  return { attempted, sent, retained, stoppedByBudget };
}