import {
  Pool,
  PoolClient,
  PostgresError,
} from "https://deno.land/x/postgres@v0.16.1/mod.ts";
import {
  type QueryArguments,
  type QueryArrayResult,
  type QueryObjectResult,
} from "https://deno.land/x/postgres@v0.16.1/query/query.ts?s=QueryArguments";
import { config } from "@/config.ts";
import * as base64 from "$std/encoding/base64.ts";
import { log } from "@/log.ts";

import {
  type Identifiable,
  type Note,
  type Team,
  type Timestamped,
  type Token,
  type TokenDigest,
  type User,
} from "@/types.ts";

import { sha256 } from "https://denopkg.com/chiefbiiko/sha256@v1.0.0/mod.ts";

export { PostgresError };
export { type QueryObjectResult };

const pool = new Pool(config.postgres.url, 3, true);

async function dbOp<T>(op: (connection: PoolClient) => Promise<T>) {
  let result = null;
  let exception = null;
  try {
    const connection = await pool.connect();
    try {
      result = await op(connection);
    } catch (err) {
      log.error("Error querying database:", { ...err });
      exception = err;
    } finally {
      connection.release();
    }
  } catch (err) {
    exception = err;
    log.error("Error connecting to database:", err);
  }
  if (exception != null) throw exception;
  return result;
}

export async function queryObject<T>(
  sql: string,
  args?: QueryArguments,
): Promise<QueryObjectResult<T> | null> {
  return await dbOp(async (connection) => {
    const result = await connection.queryObject<T>({
      camelcase: true,
      text: sql.trim(),
      args,
    });
    log.debug(result);
    return result;
  });
}

export async function queryArray<T extends []>(
  sql: string,
  args?: QueryArguments,
): Promise<QueryArrayResult<T> | null> {
  return await dbOp(async (connection) =>
    await connection.queryArray<T>({
      text: sql.trim(),
      args,
    })
  );
}

export async function listNotes(): Promise<Note[] | null> {
  return someRows(
    await queryObject<Note & User>(
      'select u.username as user_username, u.display_name as user_display_name, n.* from note n left join "user" u on u.id = n.user_id order by n.created_at desc',
    ),
  );
}

export async function getNote(
  id: string | { id: string },
): Promise<Note | null> {
  const idVal = typeof id == "object" ? id.id : id;
  log.debug("getNote id =", JSON.stringify(idVal));
  return singleRow(
    await queryObject<Note>(
      "select * from note where id = $1",
      [idVal],
    ),
  );
}

type Ungenerated<T> = Omit<T, keyof Identifiable | keyof Timestamped>;

export async function createNote(
  { content, userId }: Ungenerated<Note>,
): Promise<Note | null> {
  return singleRow(
    await queryObject<Note>(
      "insert into note (content, user_id) values ($1, $2) returning *",
      [content, userId],
    ),
  );
}

export async function createUser(
  { username, passwordDigest }: Ungenerated<User>,
): Promise<[User | null, Team | null] | null> {
  const result = singleRow(
    await queryObject<{ teamId: string; userId: string }>(
      `
    with new_user as (
      insert into "user" (username, password_digest)
        values ($username, $passwordDigest)
        returning id as user_id
    ), new_team as (
      insert into "team" (display_name)
        values ($teamName)
        returning id as team_id
    )
    insert into "team_user" (user_id, team_id, status)
      values (
        (select user_id from new_user),
        (select team_id from new_team),
        'owner'
      ) returning user_id, team_id
    `,
      { username, passwordDigest, teamName: `${username}'s First Team` },
    ),
  );
  if (!result) return null;
  const { userId, teamId } = result;
  return await Promise.all([
    getUser({ id: userId }),
    getTeam({ id: teamId }),
  ]);
}

const TOKEN_SIZE = 32;

export async function createToken(
  token: Omit<Ungenerated<Token>, "digest">,
): Promise<Token | null> {
  const intermediateToken: Partial<Token> = { ...token };
  if (!intermediateToken.bytes) {
    intermediateToken.bytes = new Uint8Array(TOKEN_SIZE);
    crypto.getRandomValues(intermediateToken.bytes);
  }
  if (!intermediateToken.digest) {
    const digest = sha256(intermediateToken.bytes);
    if (!(digest instanceof Uint8Array)) throw "token digest was non-brinary";
    intermediateToken.digest = digest;
  }
  log.debug(
    `intermediateToken bytes: ${base64.encode(intermediateToken.bytes)}`,
  );
  log.debug(
    `intermediateToken digest: ${base64.encode(intermediateToken.digest)}`,
  );
  if (!intermediateToken.data) intermediateToken.data = null;
  const result = singleRow(
    await queryObject<Token>(
      `
      insert into "user_token" (digest, user_id, data)
        values ($digest, $userId, $data)
        returning *
      `,
      intermediateToken,
    ),
  );
  if (result) return { ...intermediateToken, ...result };
  return null;
}

export async function deleteToken(
  token: TokenDigest,
) {
  const digest = sha256(base64.decode(token));
  return await queryObject(
    `
      delete from user_token where digest = $1
      `,
    [digest],
  );
}

export async function getToken(token: TokenDigest): Promise<Token | null> {
  const digest = sha256(base64.decode(token));
  return singleRow(
    await queryObject(
      `
      select * from user_token where digest = $1
      `,
      [digest],
    ),
  );
}

export async function getUser(
  { id, username }: Partial<User>,
): Promise<User | null> {
  if (!id && !username) throw "getUser called without id or username";
  const column = id ? "id" : "username";
  return singleRow(
    await queryObject<User>(
      `select * from "user" where "${column}" = $1`,
      [id || username],
    ),
  );
}

export async function getUserFromNonExpiredLoginToken(
  token: TokenDigest,
): Promise<User | null> {
  // TODO: if the token has expired, return a specific error?
  const digest = sha256(base64.decode(token));
  return singleRow(
    await queryObject<User>(
      `
      select u.* from "user_token" ut
        left join "user" u on u.id = ut.user_id
      where ut."digest" = $1
        and ut."data"->>'type' = 'login'
        and now() < (ut.created_at + '14 days'::interval)
      `,
      [digest],
    ),
  );
}

export async function getTeam(
  { id }: Partial<Team>,
): Promise<Team | null> {
  return singleRow(
    await queryObject<Team>(
      `select * from "team" where "id" = $1`,
      [id],
    ),
  );
}

function someRows<T>(result: { rows: T[] } | null): T[] | null {
  log.debug(result);
  if (!result || result.rows.length < 1) return null;
  else return result.rows;
}

function singleRow<T>(result: { rows: T[] } | null): T | null {
  if (!result || result.rows.length < 1) return null;
  else if (result.rows.length > 1) {
    log.error(
      "This singleRow result brought back more than 1 row:",
      result,
    );
    return null;
  } else return result.rows[0];
}