import crypto from "node:crypto";
import fs from "node:fs/promises";
import os from "node:os";
import path from "node:path";

import { getNostrRuntime } from "./runtime.js";

const STORE_VERSION = 2;
const PROFILE_STATE_VERSION = 1;

type NostrBusStateV1 = {
  version: 1;
  /** Unix timestamp (seconds) of the last processed event */
  lastProcessedAt: number | null;
  /** Gateway startup timestamp (seconds) - events before this are old */
  gatewayStartedAt: number | null;
};

type NostrBusState = {
  version: 2;
  /** Unix timestamp (seconds) of the last processed event */
  lastProcessedAt: number | null;
  /** Gateway startup timestamp (seconds) - events before this are old */
  gatewayStartedAt: number | null;
  /** Recent processed event IDs for overlap dedupe across restarts */
  recentEventIds: string[];
};

/** Profile publish state (separate from bus state) */
export type NostrProfileState = {
  version: 1;
  /** Unix timestamp (seconds) of last successful profile publish */
  lastPublishedAt: number | null;
  /** Event ID of the last published profile */
  lastPublishedEventId: string | null;
  /** Per-relay publish results from last attempt */
  lastPublishResults: Record<string, "ok" | "failed" | "timeout"> | null;
};

function normalizeAccountId(accountId?: string): string {
  const trimmed = accountId?.trim();
  if (!trimmed) return "default";
  return trimmed.replace(/[^a-z0-9._-]+/gi, "_");
}

function resolveNostrStatePath(
  accountId?: string,
  env: NodeJS.ProcessEnv = process.env
): string {
  const stateDir = getNostrRuntime().state.resolveStateDir(env, os.homedir);
  const normalized = normalizeAccountId(accountId);
  return path.join(stateDir, "nostr", `bus-state-${normalized}.json`);
}

function resolveNostrProfileStatePath(
  accountId?: string,
  env: NodeJS.ProcessEnv = process.env
): string {
  const stateDir = getNostrRuntime().state.resolveStateDir(env, os.homedir);
  const normalized = normalizeAccountId(accountId);
  return path.join(stateDir, "nostr", `profile-state-${normalized}.json`);
}

function safeParseState(raw: string): NostrBusState | null {
  try {
    const parsed = JSON.parse(raw) as Partial<NostrBusState> & Partial<NostrBusStateV1>;

    if (parsed?.version === 2) {
      return {
        version: 2,
        lastProcessedAt: typeof parsed.lastProcessedAt === "number" ? parsed.lastProcessedAt : null,
        gatewayStartedAt: typeof parsed.gatewayStartedAt === "number" ? parsed.gatewayStartedAt : null,
        recentEventIds: Array.isArray(parsed.recentEventIds)
          ? parsed.recentEventIds.filter((x): x is string => typeof x === "string")
          : [],
      };
    }

    // Back-compat: v1 state files
    if (parsed?.version === 1) {
      return {
        version: 2,
        lastProcessedAt: typeof parsed.lastProcessedAt === "number" ? parsed.lastProcessedAt : null,
        gatewayStartedAt: typeof parsed.gatewayStartedAt === "number" ? parsed.gatewayStartedAt : null,
        recentEventIds: [],
      };
    }

    return null;
  } catch {
    return null;
  }
}

export async function readNostrBusState(params: {
  accountId?: string;
  env?: NodeJS.ProcessEnv;
}): Promise<NostrBusState | null> {
  const filePath = resolveNostrStatePath(params.accountId, params.env);
  try {
    const raw = await fs.readFile(filePath, "utf-8");
    return safeParseState(raw);
  } catch (err) {
    const code = (err as { code?: string }).code;
    if (code === "ENOENT") return null;
    return null;
  }
}

export async function writeNostrBusState(params: {
  accountId?: string;
  lastProcessedAt: number;
  gatewayStartedAt: number;
  recentEventIds?: string[];
  env?: NodeJS.ProcessEnv;
}): Promise<void> {
  const filePath = resolveNostrStatePath(params.accountId, params.env);
  const dir = path.dirname(filePath);
  await fs.mkdir(dir, { recursive: true, mode: 0o700 });
  const tmp = path.join(
    dir,
    `${path.basename(filePath)}.${crypto.randomUUID()}.tmp`
  );
  const payload: NostrBusState = {
    version: STORE_VERSION,
    lastProcessedAt: params.lastProcessedAt,
    gatewayStartedAt: params.gatewayStartedAt,
    recentEventIds: (params.recentEventIds ?? []).filter((x): x is string => typeof x === "string"),
  };
  await fs.writeFile(tmp, `${JSON.stringify(payload, null, 2)}\n`, {
    encoding: "utf-8",
  });
  await fs.chmod(tmp, 0o600);
  await fs.rename(tmp, filePath);
}

/**
 * Determine the `since` timestamp for subscription.
 * Returns the later of: lastProcessedAt or gatewayStartedAt (both from disk),
 * falling back to `now` for fresh starts.
 */
export function computeSinceTimestamp(
  state: NostrBusState | null,
  nowSec: number = Math.floor(Date.now() / 1000)
): number {
  if (!state) return nowSec;

  // Use the most recent timestamp we have
  const candidates = [
    state.lastProcessedAt,
    state.gatewayStartedAt,
  ].filter((t): t is number => t !== null && t > 0);

  if (candidates.length === 0) return nowSec;
  return Math.max(...candidates);
}

// ============================================================================
// Profile State Management
// ============================================================================

function safeParseProfileState(raw: string): NostrProfileState | null {
  try {
    const parsed = JSON.parse(raw) as Partial<NostrProfileState>;

    if (parsed?.version === 1) {
      return {
        version: 1,
        lastPublishedAt:
          typeof parsed.lastPublishedAt === "number" ? parsed.lastPublishedAt : null,
        lastPublishedEventId:
          typeof parsed.lastPublishedEventId === "string" ? parsed.lastPublishedEventId : null,
        lastPublishResults:
          parsed.lastPublishResults && typeof parsed.lastPublishResults === "object"
            ? (parsed.lastPublishResults as Record<string, "ok" | "failed" | "timeout">)
            : null,
      };
    }

    return null;
  } catch {
    return null;
  }
}

export async function readNostrProfileState(params: {
  accountId?: string;
  env?: NodeJS.ProcessEnv;
}): Promise<NostrProfileState | null> {
  const filePath = resolveNostrProfileStatePath(params.accountId, params.env);
  try {
    const raw = await fs.readFile(filePath, "utf-8");
    return safeParseProfileState(raw);
  } catch (err) {
    const code = (err as { code?: string }).code;
    if (code === "ENOENT") return null;
    return null;
  }
}

export async function writeNostrProfileState(params: {
  accountId?: string;
  lastPublishedAt: number;
  lastPublishedEventId: string;
  lastPublishResults: Record<string, "ok" | "failed" | "timeout">;
  env?: NodeJS.ProcessEnv;
}): Promise<void> {
  const filePath = resolveNostrProfileStatePath(params.accountId, params.env);
  const dir = path.dirname(filePath);
  await fs.mkdir(dir, { recursive: true, mode: 0o700 });
  const tmp = path.join(
    dir,
    `${path.basename(filePath)}.${crypto.randomUUID()}.tmp`
  );
  const payload: NostrProfileState = {
    version: PROFILE_STATE_VERSION,
    lastPublishedAt: params.lastPublishedAt,
    lastPublishedEventId: params.lastPublishedEventId,
    lastPublishResults: params.lastPublishResults,
  };
  await fs.writeFile(tmp, `${JSON.stringify(payload, null, 2)}\n`, {
    encoding: "utf-8",
  });
  await fs.chmod(tmp, 0o600);
  await fs.rename(tmp, filePath);
}