import { sqlite } from './init.js'

const entriesPerPage = process.env.ENTRIES_PER_PAGE ?? 50

/**
 * This is a 'general' search function for the sqlite database...
 * 
 * @param {string} table The table to search in.
 * @param {string} matchField If not 'undefined' or 'null' match 'matchQuery' in this field.
 * @param {string} matchQuery The value to search for in 'matchField'.
 * @param {string} orderBy The field of which to order by, if 'null' or 'undefined' it is whatever sqlite sees as default.
 * @param {boolean} descending If true: sort in ascending order instead of ascending order.
 * @param {string} method If set to "all" it will give all results instead of only one.
 * @param {number} page The function paginates; this sets the page to look for.
 * 
 * @returns {Promise} Returns a promise which wither resolves with the data or rejects with an error.
 * 
 * @author BurnyLlama
 */
export default function searcher(table, matchField=undefined, matchQuery=undefined, orderBy=undefined, descending=false, method="get", page=1) {
    return new Promise(
        (resolve, reject) => {
            const pageCount = 
                method === "get" ? 0 :
                    parseInt(sqlite
                        .prepare(`
                            SELECT count(*) FROM $table
                            ${!matchField ?? "WHERE $matchField = $matchQuery"}
                        `)
                        .get({
                            table,
                            matchField, matchQuery
                        })
                    )

            if (method === "all" && page > pageCount)
                reject(`Page number too high! Page count: ${pageCount}`)

            const result = sqlite
                .prepare(`
                    SELECT * FROM $table
                    ${!matchField ?? "WHERE $matchField = $matchQuery"}
                    ${!orderBy ?? `"ORDER BY $orderBy" ${descending === true ? "DESC" : "ASC"}`}
                    ${method === "all" ? `LIMIT ${entriesPerPage * (page - 1)}, ${entriesPerPage}` : ""}
                `)
                [method === "all" ? "all" : "get"]({
                    table,
                    matchField, matchQuery,
                    orderBy
                })

            // This check should work?
            if ((typeof result === "object" && !result[0]) || (!result))
                reject("No search results found!")

            resolve({
                result,
                pageCount
            })
        }
    )
}