import log4js from "logger";
import nodemailer from "nodemailer";

const logger = log4js.getLogger("COMMENT_NOTIFY");
const EMAIL_REGEX = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;

type NotifyGlobalConfig = {
  enabled: boolean;
  fromEmail: string;
  smtpHost: string;
  smtpPort: number;
  smtpSecure: boolean;
  smtpUser: string;
  smtpPass: string;
};

type ReceiverProfile = {
  email: string | null;
  username: string | null;
  nickname: string | null;
};

export type ReceiverTarget =
  | { kind: "user"; userId: number }
  | { kind: "guest"; email: string };

export type NotifyDeps = {
  getParentReceiver: (parentId: number) => Promise<ReceiverTarget | null>;
  getGlobalConfig: () => Promise<NotifyGlobalConfig>;
  getReceiverNotifyEnabled: (userId: number) => Promise<boolean>;
  getReceiverProfile: (userId: number) => Promise<ReceiverProfile | null>;
  sendMail: (input: { toEmail: string; fromEmail: string; replyBody: string }) => Promise<void>;
};

function hasValue(value: string): boolean {
  return value.trim().length > 0;
}

function getReason(error: unknown): string {
  if (error instanceof Error && hasValue(error.message)) {
    return error.message;
  }
  if (typeof error === "string" && hasValue(error)) {
    return error;
  }
  return "unknown";
}

function getStack(error: unknown): string {
  if (error instanceof Error && hasValue(error.stack ?? "")) {
    return error.stack ?? "";
  }
  return "";
}

function isValidEmail(value: string): boolean {
  return EMAIL_REGEX.test(value.trim());
}

function isSmtpConfigReady(config: NotifyGlobalConfig): boolean {
  return (
    config.enabled &&
    hasValue(config.fromEmail) &&
    hasValue(config.smtpHost) &&
    hasValue(config.smtpUser) &&
    hasValue(config.smtpPass) &&
    Number.isInteger(config.smtpPort) &&
    config.smtpPort >= 1 &&
    config.smtpPort <= 65535
  );
}

async function defaultGetParentReceiver(parentId: number): Promise<ReceiverTarget | null> {
  const { dbGlobal } = await import("drizzle-pkg/lib/db");
  const { postComments } = await import("drizzle-pkg/lib/schema/content");
  const { eq } = await import("drizzle-orm");

  const [parent] = await dbGlobal
    .select({
      authorUserId: postComments.authorUserId,
      guestEmail: postComments.guestEmail,
      guestIsAnonymous: postComments.guestIsAnonymous,
    })
    .from(postComments)
    .where(eq(postComments.id, parentId))
    .limit(1);

  if (!parent) {
    return null;
  }
  if (parent.authorUserId != null) {
    return { kind: "user", userId: parent.authorUserId };
  }
  if (!parent.guestIsAnonymous && parent.guestEmail && hasValue(parent.guestEmail) && isValidEmail(parent.guestEmail)) {
    return { kind: "guest", email: parent.guestEmail.trim() };
  }
  return null;
}

async function defaultGetGlobalConfig(): Promise<NotifyGlobalConfig> {
  const { getGlobalConfigValue } = await import("../config");

  return {
    enabled: await getGlobalConfigValue("commentEmailNotifyEnabled"),
    fromEmail: await getGlobalConfigValue("commentMailFromEmail"),
    smtpHost: await getGlobalConfigValue("commentSmtpHost"),
    smtpPort: await getGlobalConfigValue("commentSmtpPort"),
    smtpSecure: await getGlobalConfigValue("commentSmtpSecure"),
    smtpUser: await getGlobalConfigValue("commentSmtpUser"),
    smtpPass: await getGlobalConfigValue("commentSmtpPass"),
  };
}

async function defaultGetReceiverNotifyEnabled(userId: number): Promise<boolean> {
  const { getMergedConfigValue } = await import("../config");
  return getMergedConfigValue(userId, "commentNotifyEnabled");
}

async function defaultGetReceiverProfile(userId: number): Promise<ReceiverProfile | null> {
  const { dbGlobal } = await import("drizzle-pkg/lib/db");
  const { users } = await import("drizzle-pkg/lib/schema/auth");
  const { eq } = await import("drizzle-orm");

  const [user] = await dbGlobal
    .select({
      email: users.email,
      username: users.username,
      nickname: users.nickname,
    })
    .from(users)
    .where(eq(users.id, userId))
    .limit(1);
  return user ?? null;
}

async function defaultSendMail(input: { toEmail: string; fromEmail: string; replyBody: string }): Promise<void> {
  const { getGlobalConfigValue } = await import("../config");

  const smtpHost = await getGlobalConfigValue("commentSmtpHost");
  const smtpPort = await getGlobalConfigValue("commentSmtpPort");
  const smtpSecure = await getGlobalConfigValue("commentSmtpSecure");
  const smtpUser = await getGlobalConfigValue("commentSmtpUser");
  const smtpPass = await getGlobalConfigValue("commentSmtpPass");

  const transporter = nodemailer.createTransport({
    host: smtpHost,
    port: smtpPort,
    secure: smtpSecure,
    connectionTimeout: 10_000,
    greetingTimeout: 10_000,
    socketTimeout: 15_000,
    auth: {
      user: smtpUser,
      pass: smtpPass,
    },
  });

  await transporter.sendMail({
    from: input.fromEmail,
    to: input.toEmail.trim(),
    subject: "[Person Panel] 你收到一条评论回复",
    text: `你收到了一条新的评论回复。\n\n回复内容：\n${input.replyBody}\n`,
  });
}

function getDefaultDeps(): NotifyDeps {
  return {
    getParentReceiver: defaultGetParentReceiver,
    getGlobalConfig: defaultGetGlobalConfig,
    getReceiverNotifyEnabled: defaultGetReceiverNotifyEnabled,
    getReceiverProfile: defaultGetReceiverProfile,
    sendMail: defaultSendMail,
  };
}

export async function notifyReplyCommentCreated(
  input: {
    postId: number;
    postOwnerUserId: number;
    commentId: number;
    parentId: number | null;
    actorUserId: number | null;
    actorGuestEmail?: string | null;
    replyBody: string;
  },
  deps: NotifyDeps = getDefaultDeps(),
): Promise<void> {
  let receiverUserId: number | null = null;
  let receiverEmail: string | null = null;
  try {
    const receiverTarget =
      input.parentId == null ? ({ kind: "user", userId: input.postOwnerUserId } as const) : await deps.getParentReceiver(input.parentId);
    if (receiverTarget == null) {
      return;
    }

    const globalConfig = await deps.getGlobalConfig();
    if (!isSmtpConfigReady(globalConfig)) {
      return;
    }

    if (receiverTarget.kind === "user") {
      receiverUserId = receiverTarget.userId;
      if (input.actorUserId != null && input.actorUserId === receiverUserId) {
        return;
      }

      const receiverNotifyEnabled = await deps.getReceiverNotifyEnabled(receiverUserId);
      if (!receiverNotifyEnabled) {
        return;
      }

      const receiver = await deps.getReceiverProfile(receiverUserId);
      if (!receiver?.email || !hasValue(receiver.email)) {
        return;
      }
      if (!isValidEmail(receiver.email)) {
        return;
      }
      receiverEmail = receiver.email.trim();
    } else {
      receiverEmail = receiverTarget.email.trim();
      const actorGuestEmail = input.actorGuestEmail?.trim();
      if (actorGuestEmail && receiverEmail.toLowerCase() === actorGuestEmail.toLowerCase()) {
        return;
      }
    }

    await deps.sendMail({
      toEmail: receiverEmail,
      fromEmail: globalConfig.fromEmail,
      replyBody: input.replyBody,
    });
  } catch (error) {
    logger.warn("failed to send reply comment notify email", {
      postId: input.postId,
      commentId: input.commentId,
      receiverUserId,
      receiverEmail,
      reason: getReason(error),
      stack: getStack(error),
    });
  }
}