import type { QueryKey, UseQueryOptions } from '@tanstack/react-query'
import { Query } from 'components/grid/query/Query'
import type { Filter, SupaTable } from 'components/grid/types'
import { ImpersonationRole, wrapWithRoleImpersonation } from 'lib/role-impersonation'
import { useIsRoleImpersonationEnabled } from 'state/role-impersonation-state'
import { ExecuteSqlData, ExecuteSqlError, useExecuteSqlQuery } from '../sql/execute-sql-query'
import { formatFilterValue } from './utils'

type GetTableRowsCountArgs = {
  table?: SupaTable
  filters?: Filter[]
  enforceExactCount?: boolean
  impersonatedRole?: ImpersonationRole
}

export const THRESHOLD_COUNT = 50000
const COUNT_ESTIMATE_SQL = `
CREATE OR REPLACE FUNCTION pg_temp.count_estimate(
    query text
) RETURNS integer LANGUAGE plpgsql AS $$
DECLARE
    plan jsonb;
BEGIN
    EXECUTE 'EXPLAIN (FORMAT JSON)' || query INTO plan;
    RETURN plan->0->'Plan'->'Plan Rows';
END;
$$;
`.trim()

export const getTableRowsCountSqlQuery = ({
  table,
  filters = [],
  enforceExactCount = false,
}: GetTableRowsCountArgs) => {
  if (!table) return ``

  if (enforceExactCount) {
    const query = new Query()
    let queryChains = query.from(table.name, table.schema ?? undefined).count()
    filters
      .filter((x) => x.value && x.value !== '')
      .forEach((x) => {
        const value = formatFilterValue(table, x)
        queryChains = queryChains.filter(x.column, x.operator, value)
      })
    return `select (${queryChains.toSql().slice(0, -1)}), false as is_estimate;`
  } else {
    const selectQuery = new Query()
    let selectQueryChains = selectQuery.from(table.name, table.schema ?? undefined).select('*')
    filters
      .filter((x) => x.value && x.value != '')
      .forEach((x) => {
        const value = formatFilterValue(table, x)
        selectQueryChains = selectQueryChains.filter(x.column, x.operator, value)
      })
    const selectBaseSql = selectQueryChains.toSql()

    const countQuery = new Query()
    let countQueryChains = countQuery.from(table.name, table.schema ?? undefined).count()
    filters
      .filter((x) => x.value && x.value != '')
      .forEach((x) => {
        const value = formatFilterValue(table, x)
        countQueryChains = countQueryChains.filter(x.column, x.operator, value)
      })
    const countBaseSql = countQueryChains.toSql().slice(0, -1)

    const sql = `
${COUNT_ESTIMATE_SQL}

with approximation as (
    select reltuples as estimate
    from pg_class
    where oid = ${table.id}
)
select 
  case 
    when estimate = -1 then (select pg_temp.count_estimate('${selectBaseSql.replaceAll("'", "''")}'))
    when estimate > ${THRESHOLD_COUNT} then ${filters.length > 0 ? `pg_temp.count_estimate('${selectBaseSql.replaceAll("'", "''")}')` : 'estimate'}
    else (${countBaseSql})
  end as count,
  estimate = -1 or estimate > ${THRESHOLD_COUNT} as is_estimate
from approximation;
`.trim()

    return sql
  }
}

export type TableRowsCount = {
  count: number
  is_estimate?: boolean
}

export type TableRowsCountVariables = GetTableRowsCountArgs & {
  projectRef?: string
  connectionString?: string
  queryKey?: QueryKey
}

export type TableRowsCountData = TableRowsCount
export type TableRowsCountError = ExecuteSqlError

export const useTableRowsCountQuery = <TData extends TableRowsCountData = TableRowsCountData>(
  {
    projectRef,
    connectionString,
    queryKey,
    table,
    enforceExactCount,
    impersonatedRole,
    ...args
  }: TableRowsCountVariables,
  options: UseQueryOptions<ExecuteSqlData, TableRowsCountError, TData> = {}
) => {
  const isRoleImpersonationEnabled = useIsRoleImpersonationEnabled()

  return useExecuteSqlQuery(
    {
      projectRef,
      connectionString,
      sql: wrapWithRoleImpersonation(
        getTableRowsCountSqlQuery({ table, enforceExactCount, ...args }),
        { projectRef: projectRef ?? 'ref', role: impersonatedRole }
      ),
      queryKey: [
        ...(queryKey ?? []),
        {
          table: { name: table?.name, schema: table?.schema },
          enforceExactCount,
          impersonatedRole,
          ...args,
        },
      ],
      isRoleImpersonationEnabled,
    },
    {
      select(data) {
        return {
          count: data.result[0].count,
          is_estimate: data.result[0].is_estimate ?? false,
        } as TData
      },
      enabled: typeof projectRef !== 'undefined' && typeof table !== 'undefined',
      ...options,
    }
  )
}