import {
  Pool,
  PoolClient,
  PostgresError,
  Transaction,
  type TransactionOptions,
} 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 * as base64 from "$std/encoding/base64.ts";
import { log } from "@/log.ts";

import { type PostgresConfig } from "@/config.ts";
import {
  type Display,
  type Note,
  type Playlist,
  type Team,
  type TeamUser,
  type Token,
  type TokenDigest,
  type Ungenerated,
  type User,
} from "@/types.ts";

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

export { PostgresError };
export { type QueryObjectResult };

let pool: Pool;

export function initDatabaseConnectionPool({ url }: PostgresConfig) {
  pool = new Pool(url, 3, true);
  testDbConnection();
}

export async function testDbConnection(): Promise<boolean> {
  try {
    await dbOp((conn) => conn.queryObject("select 1"));
    log.info("Successfully connected to database");
    return true;
  } catch (e) {
    log.critical("Failed to connect to database:", e);
    return false;
  }
}

type QueryResult<T> = { rows: T[] } | null;

class NoRowsError<T> extends Error {
  result: QueryResult<T>;

  constructor(result: QueryResult<T>) {
    const message = `No rows in query result: ${result}`;
    super(message);
    this.result = result;
  }
}

class TooManyRowsError<T> extends Error {
  result: QueryResult<T>;

  constructor(result: QueryResult<T>) {
    const message = `Too many rows in query result: ${result}`;
    super(message);
    this.result = result;
  }
}

function someRows<T>(result: QueryResult<T>): T[] {
  if (!result || result.rows.length < 1) {
    throw new NoRowsError(result);
  } else {
    return result.rows;
  }
}

function singleRow<T>(result: QueryResult<T>): T {
  if (!result || result.rows.length < 1) throw new NoRowsError(result);
  else if (result.rows.length > 1) throw new TooManyRowsError(result);
  else return result.rows[0];
}

export async function dbOp<T>(
  op: (connection: PoolClient) => Promise<T>,
): Promise<T> {
  let result: T | null = 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.critical("Error connecting to database:", err);
  }
  if (exception != null) throw exception;
  if (result == null) {
    throw "Database operation failed to properly load a result";
  }
  return result;
}

export async function queryObject<T>(
  sql: string,
  args?: QueryArguments,
  connection?: PoolClient | Transaction,
): Promise<QueryObjectResult<T> | null> {
  console.debug(`queryObject: ${sql}`);
  if (!connection) {
    return await dbOp(async (connection) => {
      return await queryObject(sql, args, connection);
    });
  } else {
    const result = await connection.queryObject<T>({
      camelcase: true,
      text: sql.trim(),
      args,
    });
    log.debug("queryObject Result:", result);
    return result;
  }
}

export async function queryArray<T extends []>(
  sql: string,
  args?: QueryArguments,
  connection?: PoolClient,
): Promise<QueryArrayResult<T> | null> {
  console.debug(`queryArray: ${sql}`);
  if (!connection) {
    return await dbOp(async (connection) => {
      return await queryArray<T>(sql, args, connection);
    });
  } else {
    const result = await connection.queryArray<T>({
      text: sql.trim(),
      args,
    });
    log.debug("queryArray Result:", result);
    return result;
  }
}

export async function listNotes(): Promise<(Note & User)[]> {
  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> {
  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],
    ),
  );
}

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 createTeamUser(
  { teamId, userId, status }: TeamUser,
  transaction?: Transaction,
): Promise<TeamUser | null> {
  return singleRow(
    await queryObject<TeamUser>(
      `
      insert into "team_user" (user_id, team_id, status)
        values (
          $userId,
          $teamId,
          $status
        ) returning *`,
      { userId, teamId, status },
      transaction,
    ),
  );
}

export async function createTeam(
  data: {
    team: Ungenerated<Team>;
    creator?: User;
  },
  transaction?: Transaction,
): Promise<Team> {
  console.debug("createTeam tx:", transaction);
  if (!transaction) {
    return await wrapWithTransaction<Team>(
      "createTeam",
      (t) => createTeam(data, t),
    );
  } else {
    try {
      const { team: { displayName }, creator } = data;
      const team = singleRow(
        await queryObject<Team>(
          `insert into "team" (display_name) values ($displayName) returning *`,
          { displayName },
          transaction,
        ),
      );
      if (creator) {
        await createTeamUser(
          { teamId: team.id, userId: creator.id, status: "owner" },
          transaction,
        );
      }
      return team;
    } catch (e) {
      console.error("Error creating team:", e);
      throw e;
    }
  }
}

export async function wrapWithTransaction<T>(
  transactionName: string,
  callback: (transaction: Transaction) => Promise<T>,
  transactionOptions?: TransactionOptions,
): Promise<T> {
  const result = await dbOp<T>(async (connection) => {
    try {
      const transaction = connection.createTransaction(
        transactionName,
        transactionOptions,
      );
      try {
        await transaction.begin();
        console.debug(
          `started ${transactionName} tx with options ${
            JSON.stringify(transactionOptions)
          }:`,
          transaction,
        );
        const result: T = await callback(transaction);
        await transaction.commit();
        return result;
      } catch (e) {
        await transaction.rollback();
        console.error("Failed to complete transaction:", e);
        throw e;
      }
    } catch (e) {
      console.error("Failed to create transaction");
      throw e;
    }
  });
  if (!result) throw "Failed to finish transactional database operation";
  return result;
}

export async function createUser(
  data: Ungenerated<User>,
  transaction?: Transaction,
): Promise<User> {
  if (!transaction) {
    return await wrapWithTransaction<User>(
      "createUser",
      (t) => createUser(data, t),
    );
  } else {
    try {
      const { username, passwordDigest } = data;
      const user = singleRow(
        await queryObject<User>(
          `insert into "user" (username, password_digest)
            values ($username, $passwordDigest)
            returning *`,
          { username, passwordDigest },
          transaction,
        ),
      );
      await createTeam({
        team: { displayName: `${username}'s Team` },
        creator: user,
      }, transaction);

      return user;
    } catch (e) {
      console.error("Error creating user:", e);
      throw e;
    }
  }
}

const TOKEN_SIZE = 32;

export async function createToken(
  token: Omit<Ungenerated<Token>, "digest">,
): Promise<Token> {
  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: ${base64.encode(intermediateToken.digest)}`,
  );
  if (!intermediateToken.data) intermediateToken.data = null;
  const result = singleRow(
    await queryObject<Token>(
      `
      insert into "token" (digest, user_id, data)
        values ($digest, $userId, $data)
        returning *
      `,
      intermediateToken,
    ),
  );
  return { ...intermediateToken, ...result };
}

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

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

export async function getUser(
  idOrUsername: { id: string } | { username: string } | string,
): Promise<User> {
  if (typeof idOrUsername == "string") {
    try {
      return singleRow(
        await queryObject<User>(
          `select * from "user" where "id" = $1`,
          [idOrUsername],
        ),
      );
    } catch (_) {
      return singleRow(
        await queryObject<User>(
          `select * from "user" where "username" = $1`,
          [idOrUsername],
        ),
      );
    }
  } else {
    const column = "id" in idOrUsername ? "id" : "username";
    return singleRow(
      await queryObject<User>(
        `select * from "user" where "${column}" = $1`,
        [(idOrUsername as { id?: string; username?: string })[column]],
      ),
    );
  }
}

// TODO: refresh token?

export async function getUserFromNonExpiredLoginToken(
  token: TokenDigest,
): Promise<User> {
  // TODO: if the token has expired, return a specific error?
  const digest = sha256(base64.decode(token));
  return singleRow(
    await queryObject<User>(
      `select u.* from "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> {
  return singleRow(
    await queryObject<Team>(
      `select * from "team" where "id" = $1`,
      [id],
    ),
  );
}

export async function getUserTeams(
  { id }: Partial<User>,
): Promise<Team[]> {
  return someRows(
    await queryObject<Team>(
      `select t.* from "team" t
        left join "team_user" tu on t.id = tu.team_id
       where tu."user_id" = $1`,
      [id],
    ),
  );
}
export async function getTeamUsers(
  { id }: Partial<Team>,
): Promise<User[]> {
  return someRows(
    await queryObject<User>(
      `select u.* from "user" u
        left join "team_user" tu on u.id = tu.user_id
       where tu."team_id" = $1`,
      [id],
    ),
  );
}

// export async function createDisplay(display: Ungenerated<Display>, transaction?: Transaction) {
//   display
// }