import fs from "node:fs"
import path from "node:path"
import { extractRowsFromSQLValues } from "./utils.js"

const SQL_DUMP_PATH = path.join(process.cwd(), "dump")
const SQL_OUTPUT_PATH = path.join(process.cwd(), "sql")

/**
 * @typedef {Record<string, number>} WikipediaPages
 *
 * Object to store pages from Wikipedia:
 * - Key: page title sanitized - The real title shown is this title with underscores (_) converted to spaces ( ).
 * - Value: page id.
 */

/**
 * Function to clean the `page.sql` file by:
 * - Removing all lines that don't start with `INSERT INTO...`.
 * - Filter by keeping rows where `page_namespace` (2nd column) is equal to 0, and where `page_is_redirect` (4th column) is equal to false (0).
 * - Only keep columns `page_id` (1st column) and `page_title` (3rd column).
 * @returns {Promise<WikipediaPages>}
 */
const cleanPagesSQL = async () => {
  /** @type {WikipediaPages} */
  const wikipediaPages = {}

  const INSERT_INTO_START_INPUT = "INSERT INTO `page` VALUES "
  const sqlInputPath = path.join(SQL_DUMP_PATH, "page.sql")
  const sqlInputStat = await fs.promises.stat(sqlInputPath)
  const sqlInputFileStream = fs.createReadStream(sqlInputPath, "utf-8")

  let isInsideInsert = false
  let current = ""
  let lastPercent = 0

  return await new Promise((resolve, reject) => {
    sqlInputFileStream
      .on("data", (dataInput) => {
        const bytesReadRatio = sqlInputFileStream.bytesRead / sqlInputStat.size
        const bytesReadPercent = bytesReadRatio * 100

        if (bytesReadPercent - lastPercent >= 1) {
          console.log(
            `Bytes read (${bytesReadPercent.toFixed(2)}%): ${sqlInputFileStream.bytesRead} / ${sqlInputStat.size}`,
          )
          lastPercent = bytesReadPercent
        }

        let data = current + dataInput

        if (!isInsideInsert) {
          const lines = data.split("\n").filter((line) => {
            return line.startsWith(INSERT_INTO_START_INPUT)
          })
          const [line] = lines
          if (line == null) {
            sqlInputFileStream.close()
            return reject(new Error(`No "${INSERT_INTO_START_INPUT}" found.`))
          }
          isInsideInsert = true
          const lineStripped = line.slice(INSERT_INTO_START_INPUT.length)
          data = lineStripped
        }

        const { rows, unCompleted } = extractRowsFromSQLValues(data)
        current = unCompleted

        for (const row of rows) {
          if (row.length !== 12) {
            sqlInputFileStream.close()
            console.error([row])
            return reject(new Error(`Invalid Row values.`))
          }

          const id = Number.parseInt(row[0] ?? "0", 10)
          const namespace = row[1] ?? ""
          const title = row[2] ?? ""
          const isRedirect = row[3] === "1"

          if (namespace === "0" && !isRedirect) {
            wikipediaPages[title] = id
          }
        }
      })
      .on("error", (error) => {
        return reject(error)
      })
      .on("close", () => {
        return resolve(wikipediaPages)
      })
  })
}

const wikipediaPages = await cleanPagesSQL()

const cleanPagesSQLWriteToFile = async () => {
  const sqlOutputPath = path.join(SQL_OUTPUT_PATH, "2-pages-inserts.sql")
  const INSERT_INTO_START_OUTPUT = "INSERT INTO pages VALUES "

  const wikipediaPagesString = Object.entries(wikipediaPages)
    .map(([title, id]) => {
      return `(${id},${title})`
    })
    .join(",")

  await fs.promises.writeFile(
    sqlOutputPath,
    `${INSERT_INTO_START_OUTPUT}${wikipediaPagesString};`,
    { encoding: "utf-8" },
  )
}

await cleanPagesSQLWriteToFile()