unsql.js

// @ts-check
const { colors, handleError, handleQueryDebug } = require("./helpers/console.helper")
const { prepSelect, prepWhere, prepJoin, prepOrderBy, patchGroupBy, patchLimit, prepEncryption, isVariable } = require("./helpers/main.helper")
const { prepName } = require("./helpers/name.helper")

/**
 * UnSQL is JavaScript based library to interact with structured databases (MySQL). It provides clean and easy interface for interaction for faster and smooth developers' experience.
 * @class
 * @alias UnSQL
 * @classdesc All model classes shall extend using UnSQL base class to access advanced functionalities
 * @namespace UnSQL
 * @author Siddharth Tiwari <dev.unsql@gmail.com>
 */
class UnSQL {

    /**
     * config is a static property object, used to declare configurations relating to a model class
     * @type {import("./defs/types").ConfigObject} (required) defines configurations for this model class
     * @static
     * @public
     * @memberof UnSQL
     */
    static config = {
        table: '',
        safeMode: true,
        devMode: false
    }

    static _variableCount = 0
    static isMySQL = false
    static isPostgreSQL = false
    static isSQLite = false

    /**
     * Find method
     * @method find
     * @description find method is used to fetch records from the database table
     * 
     * @param {Object} findParam (optional)
     * @param {string} [findParam.alias] (optional) local reference name for table mapped to this model
     * @param {import("./defs/types").SelectObject} [findParam.select] (optional) limits columns to be extracted, accepts an array of value(s), column name(s), wrapper methods etc
     * @param {import("./defs/types").JoinObject} [findParam.join] (optional) enables association of child table(s) to this model class
     * @param {import("./defs/types").WhereObject} [findParam.where] (optional) filter record(s) based on conditions
     * @param {'and'|'or'} [findParam.junction] (optional) defines the clause ('and'|'or') used to connect conditions inside 'where' and 'having' property
     * @param {string[]} [findParam.groupBy] (optional) groups record(s) based on single (or list of) column(s)
     * @param {import("./defs/types").HavingObject} [findParam.having] (optional) similar to 'where', filters record(s) additionally allows filter using aggregate methods
     * @param {{[column:string]:('asc'|'desc')}} [findParam.orderBy] (optional) re-order extracted record(s) based on single (or list of) column(s)
     * @param {number} [findParam.limit] (optional) limits the number of record(s) to be fetched
     * @param {number} [findParam.offset] (optional) sets the starting index for records to be fetched
     * @param {import("./defs/types").EncryptionConfig} [findParam.encryption] (optional) defines query level encryption configurations
     * @param {import("./defs/types").DebugTypes} [findParam.debug] (optional) enables different debug modes
     * @param {Object} [findParam.session] (optional)
     * 
     * @returns {Promise<{success:false, error?:object}|{success:true, result?:object[], insertId?:number, changes?:number}>} Promise resolving with two parameters: boolean 'success' and either 'error' or 'result'
     * 
     * @static
     * @memberof UnSQL
     */
    static async find({ alias = undefined, select = [], join = [], where = {}, junction = 'and', groupBy = [], having = {}, orderBy = {}, limit = undefined, offset = undefined, encryption = {}, debug = false, session = undefined } = {}) {

        const defaultResp = handleDefaults(this)
        if (!defaultResp?.success) return defaultResp
        patchDefaults(this)
        const values = []
        const sqlParts = []

        try {
            sqlParts.push(`SELECT ${prepSelect({ alias, select, values, encryption, ctx: this })} FROM ${this?.isMySQL ? '??' : `"${this.config?.table}"`}`)
            if (this.isMySQL) values.push(this.config?.table)
            if (alias) {
                if (this.isMySQL) values.push(alias)
                sqlParts.push(this?.isMySQL ? '??' : `"${alias}"`)
            }
            if (join.length) sqlParts.push(prepJoin({ alias, join, values, encryption, ctx: this }))
            if (Object.keys(where).length > 0) sqlParts.push(`WHERE ${prepWhere({ alias, where, junction, values, encryption, ctx: this })}`)
            if (groupBy.length) sqlParts.push(patchGroupBy({ groupBy, alias, values, ctx: this }))
            if (Object.keys(having).length > 0) sqlParts.push(`HAVING ${prepWhere({ alias, where: having, junction, values, encryption, ctx: this })}`)
            if (Object.keys(orderBy).length > 0) sqlParts.push(prepOrderBy({ alias, orderBy, values, ctx: this }))
            if (typeof limit === 'number') sqlParts.push(patchLimit(limit, values, this))
            if (typeof offset === 'number') sqlParts.push(patchLimit(offset, values, this, 'OFFSET'))

            const debugMessage = 'Fetched records in'
            return await handleExecutions[this?.config?.dialect]({ sql: sqlParts.join(' '), values, encryption, debug, session, config: this.config, debugMessage, methodType: 'all' })

        } catch (error) {
            handleError(debug, error)
            return { success: false, error: error.sqlMessage || error.message || error }
        }
    }

    /**
     * @method save
     * @description save method used in insert / update / upsert record(s) in the database table
     * @param {Object} saveParam (optional)
     * @param {string} [saveParam.alias] (optional) local reference name for table mapped to this model
     * @param {Object|Array<object>} saveParam.data object / array of objects to be inserted into the database table
     * @param {import("./defs/types").WhereObject} [saveParam.where] (optional) used to filter records to be updated
     * @param {'and'|'or'} [saveParam.junction] (optional) defines default behavior that is used to join different 'child properties' inside 'where' property, default value is 'and'
     * @param {Array<string>} [saveParam.groupBy] (optional) allows to group result based on single (or list of) column(s)
     * @param {import("./defs/types").HavingObject} [saveParam.having] (optional) allows to perform comparison on the group of records, accepts nested conditions as object along with aggregate method wrappers viz. {sum:...}, {avg:...}, {min:...}, {max:...} etc
     * @param {Object} [saveParam.upsert] (optional) object data to be updated in case of 'duplicate key entry' found in the database
     * @param {{[column:string]:{secret?:string, iv?:string, sha?:import("./defs/types").EncryptionSHAs} }} [saveParam.encrypt] (optional) define encryption overrides for column(s)
     * @param {import("./defs/types").EncryptionConfig} [saveParam.encryption] (optional) defines query level encryption configurations
     * @param {import("./defs/types").DebugTypes} [saveParam.debug] (optional) enables various debug mode
     * @param {Object} [saveParam.session] (optional) enables various debug mode
     * @returns {Promise<{success:boolean, error?:*, result?:*}>} Promise resolving with two parameters: boolean 'success' and either 'error' or 'result'
     * @static
     * @memberof UnSQL
     */
    static async save({ alias = undefined, data = [], where = {}, junction = 'and', groupBy = [], having = {}, upsert = {}, encrypt = {}, encryption = {}, debug, session }) {

        patchDefaults(this)

        const defaultResp = handleDefaults(this)

        if (!defaultResp?.success) return defaultResp

        if (Array.isArray(data) && (Object.keys(where).length || Object.keys(having).length || groupBy.length)) {
            return { success: false, error: 'Invalid combination to update multiple records, only single object inside "data" property can be passed while updating records, array of objects detected' }
        }

        if (!Object.keys(where).length && !Object.keys(having).length && this?.config?.dialect != 'mysql') data = Array.isArray(data) ? data : [data]

        const values = []
        const sqlParts = []

        sqlParts.push(`${Object.keys(where).length ? 'UPDATE' : `INSERT ${Object.keys(upsert).length > 0 && this?.config?.dialect === 'sqlite' ? 'OR REPLACE ' : ''}INTO`} ${this?.isMySQL ? '??' : `"${this.config?.table}"`}`)
        if (this.isMySQL) values.push(this.config?.table)
        if (alias) {
            if (this.isMySQL) values.push(alias)
            sqlParts.push(this?.isMySQL ? '??' : `"${alias}"`)
        }

        try {

            switch (true) {
                // handle if data is array of json object(s)
                case Array.isArray(data): {

                    const columnPlaceholders = []
                    const valuePlaceholders = []
                    const columnNames = new Set()
                    const dataLength = data.length

                    console.info(colors.cyan, (dataLength > 1000 ? 'Large dataset detected, p' : 'P') + 'lease wait while UnSQL prepares query for each record, this might take few seconds...', colors.reset)

                    // loop over records
                    for (let i = 0; i < dataLength; i++) {
                        for (const column in data[i]) {
                            if (!columnNames.has(column)) {
                                columnPlaceholders.push(this.isMySQL ? '??' : `"${column}"`)
                                if (this.isMySQL) values.push(column)
                                columnNames.add(column)
                            }
                        }
                    } // main loop ends

                    sqlParts.push(`(${columnPlaceholders.join(', ')})`)

                    sqlParts.push('VALUES')

                    for (let i = 0; i < dataLength; i++) {
                        const row = []
                        for (const column of columnNames) {
                            if (typeof data[i][column] == 'object') {
                                if (this.isPostgreSQL) row.push(prepJsonbUpdate(column, data[i][column], (Object.keys(where).length || Object.keys(having).length)))
                                else if (this.isMySQL) {
                                    row.push('?')
                                    values.push(JSON.stringify(data[i][column]))
                                }
                                continue
                            }
                            row.push(this.isMySQL ? '?' : `$${this._variableCount++}`)
                            values.push(data[i][column] == 'null' || data[i][column] == null || data[i][column] == undefined || data[i][column] == 'undefined' ? null : data[i][column])
                        }
                        valuePlaceholders.push(`(${row.join(', ')})`)
                    }

                    sqlParts.push(valuePlaceholders.join(', '))
                    break
                }

                case typeof data === 'object': {

                    const entries = Object.entries(data)
                    const setEntries = []
                    for (let i = 0; i < entries.length; i++) {
                        const col = entries[i][0]
                        const val = entries[i][1]
                        const localSql = []
                        localSql.push(this.isMySQL ? '?? =' : `"${col}" =`)
                        if (this.isMySQL) values.push(col)
                        if (typeof val == 'object' && this.isPostgreSQL) {
                            localSql.push(prepJsonbUpdate(col, val, (Object.keys(where).length || Object.keys(having).length)))
                            continue
                        }
                        if (typeof val == 'object') values.push(JSON.stringify(val))
                        else values.push(val == 'null' || val == 'undefined' || val == undefined ? null : val)
                        if (encrypt[col]) {
                            localSql.push(prepEncryption({ placeholder: (this?.isPostgreSQL ? `$${this._variableCount++}` : '?'), col, ctx: this, encrypt, encryption, values }))
                            continue
                        }
                        localSql.push(this.isPostgreSQL ? `$${this._variableCount++}` : '?')
                        setEntries.push(localSql.join(' '))
                    }

                    sqlParts.push(`SET ${setEntries.join(', ')}`)

                    if (Object.keys(upsert).length) { // if upsert object is provided

                        const upsertEntries = Object.entries(upsert)
                        const duplicateEntries = []
                        for (let i = 0; i < upsertEntries.length; i++) {
                            const col = upsertEntries[i][0]
                            const val = upsertEntries[i][1]
                            const localSql = []
                            localSql.push(this.isMySQL ? '?? =' : `"${col}" =`)
                            if (this.isMySQL) values.push(col)
                            if (typeof val == 'object' && this.isPostgreSQL) {
                                localSql.push(prepJsonbUpdate(col, val, (Object.keys(where).length || Object.keys(having).length)))
                                continue
                            }
                            if (typeof val == 'object') values.push(JSON.stringify(val))
                            else values.push(val == 'null' || val == 'undefined' || val == undefined ? null : val)
                            if (encrypt[col]) {
                                localSql.push(prepEncryption({ placeholder: (this?.isPostgreSQL ? `$${this._variableCount++}` : '?'), col, ctx: this, encrypt, encryption, values }))
                                continue
                            }
                            localSql.push(this.isPostgreSQL ? `$${this._variableCount++}` : '?')
                            duplicateEntries.push(localSql.join(' '))
                        }

                        const conflictPrefix = {
                            mysql: 'ON DUPLICATE KEY UPDATE',
                            postgresql: 'ON CONFLICT DO UPDATE SET'
                        }
                        sqlParts.push(`${conflictPrefix[this?.config?.dialect] || ''} ${duplicateEntries.join(', ')}`)
                    }
                    if (Object.keys(where).length) sqlParts.push(`WHERE ${prepWhere({ alias, where, junction, values, encryption, ctx: this })}`)
                    if (groupBy.length > 0) sqlParts.push(patchGroupBy({ groupBy, alias, values, ctx: this }))
                    if (Object.keys(having).length) sqlParts.push(`HAVING ${prepWhere({ alias, where: having, junction, values, encryption, ctx: this })}`)

                    break
                }

                default:
                    return { success: false, error: "Invalid data type! Data argument accepts only object or array of objects" }
            }

            const debugMessage = `${(Object.keys(where).length > 0) || (Object.keys(having).length > 0) ? 'Updated' : 'Inserted'} records in`
            return await handleExecutions[this.config.dialect]({ sql: sqlParts.join(' '), values, encryption, debug, session, config: this?.config, debugMessage, methodType: 'run' })
        } catch (error) {
            return { success: false, error }
        }
    }


    /**
     * @method delete
     * @description delete method is used to remove record(s) from the database table
     * 
     * @param {Object} deleteParam delete query object definition
     * @param {string} [deleteParam.alias] (optional) local alias name for the database table
     * @param {import("./defs/types").WhereObject} [deleteParam.where] (optional) filter record(s) to be updated
     * @param {'and'|'or'} [deleteParam.junction] (optional) defines default behavior that is used to join different 'child properties' inside 'where' property, default value is 'and'
     * @param {Array<string>} [deleteParam.groupBy] (optional) allows to group result based on single (or list of) column(s)
     * @param {import("./defs/types").HavingObject} [deleteParam.having] (optional) allows to perform comparison on the group of records, accepts nested conditions as object along with aggregate method wrappers viz. {sum:...}, {avg:...}, {min:...}, {max:...} etc
     * @param {import("./defs/types").EncryptionConfig} [deleteParam.encryption] (optional) defines query level encryption configurations
     * @param {import("./defs/types").DebugTypes} [deleteParam.debug] (optional) enables various debug mode
     * @param {Object} [deleteParam.session] (optional) global session reference for transactions and rollback
     * 
     * @returns {Promise<{success:boolean, error?:object, result?:object}>} Promise resolving with two parameters: boolean 'success' and either 'error' or 'result'
     * 
     * @static
     * @memberof UnSQL
     */
    static async delete({ alias = undefined, where = {}, junction = 'and', groupBy = [], having = {}, debug = false, encryption = undefined, session = undefined } = {}) {

        patchDefaults(this)

        const defaultResp = handleDefaults(this)

        if (!defaultResp.success) return defaultResp

        // handle delete all if safe mode is active
        if (!Object.keys(where).length && this?.config?.safeMode) {
            console.error(colors.red + `Delete all records from database table in 'safeMode' is prohibited!` + colors.reset)
            return { success: false, error: `Delete all is disabled in 'safeMode' (default 'true') inside 'config' property of '${this.name}' model class` }
        }

        const values = []
        const sqlParts = [`DELETE FROM ${(this?.isMySQL ? '??' : `"${this?.config?.table}"`)}`]
        if (this.isMySQL) values.push(this.config?.table)
        if (alias) {
            if (this.isMySQL) values.push(alias)
            sqlParts.push(this?.isMySQL ? '??' : `"${alias}"`)
        }

        if (Object.keys(where).length) sqlParts.push(`WHERE ${prepWhere({ alias, where, junction, values, encryption, ctx: this })}`)

        if (groupBy.length > 0) sqlParts.push(patchGroupBy({ groupBy, alias, values, ctx: this }))

        if (Object.keys(having).length) sqlParts.push(`HAVING ${prepWhere({ alias, where: having, junction, values, encryption, ctx: this })}`)

        const debugMessage = `Removed record(s) from '${this?.config?.table}' table`
        return await handleExecutions[this.config.dialect]({ sql: sqlParts.join(' '), values, encryption, debug, session, config: this.config, debugMessage, methodType: 'run' })
    }

    /**
     * @method rawQuery
     * @description rawQuery method is used to execute raw SQL query on the database
     * @param {Object} rawQueryParams
     * @param {string} rawQueryParams.sql (required) SQL query to be executed
     * @param {Array<any>|Object} [rawQueryParams.values] (optional) values to be interpolated in the query
     * @param {import("./defs/types").EncryptionConfig} [rawQueryParams.encryption] (optional) enables debug mode
     * @param {import("./defs/types").DebugTypes} [rawQueryParams.debug] (optional) enables debug mode
     * @param {boolean} [rawQueryParams.multiQuery] (optional) flag if sql contains multiple queries (only in 'mysql'), default is false
     * @param {Object} [rawQueryParams.session] (optional) global session reference for transactions and rollback
     * @param {'run'|'all'|'exec'} [rawQueryParams.methodType=all] (optional) used only with 'sqlite'
     * @returns {Promise<{success:boolean, error?:object, result?:object}>} Promise resolving with two parameters: boolean 'success' and either 'error' or 'result'
     */
    static async rawQuery({ sql = '', values = [], debug = false, encryption = undefined, session = undefined, multiQuery = false, methodType = 'all' }) {
        const debugMessage = `Executed raw query in`
        return await handleExecutions[this?.config?.dialect || 'mysql']({ sql, values, encryption, debug, session, config: this.config, methodType, multiQuery, debugMessage })
    }

    /**
     * export record(s) from the table
     * @method export
     * @description This method exports record(s) (filtered/un-filtered) from the database table in form of the 'Json Array' into a json file
     * @param {Object} exportParam
     * @param {string|UnSQL} [exportParam.target] (optional) name of the file dynamically created '.json' file or reference to a valid UnSQL model class, defaults to the table name of exporting model class
     * @param {string} [exportParam.directory] (optional) rename default export directory
     * @param {import("./defs/types").SelectObject} [exportParam.select] (optional) limit column(s) to be extracted
     * @param {string} [exportParam.alias] (optional) local reference name to the exporting model
     * @param {import("./defs/types").JoinObject} [exportParam.join] (optional) join child table(s)
     * @param {import("./defs/types").WhereObject} [exportParam.where] (optional) filter record(s) using condition(s)
     * @param {string[]} [exportParam.groupBy] (optional) group record(s) based on column(s)
     * @param {import("./defs/types").HavingObject} [exportParam.having] (optional) filter record(s) using condition(s)/aggregate wrappers
     * @param {{[key:string]:'asc'|'desc'}} [exportParam.orderBy] (optional) 
     * @param {number} [exportParam.limit] (optional) limit record(s) to be extracted
     * @param {number} [exportParam.offset] (optional) set starting index
     * @param {{[column:string]:import("./defs/types").EncryptionConfig}} [exportParam.encrypt] (optional) set starting index
     * @param {import("./defs/types").EncryptionConfig} [exportParam.encryption] (optional) set encryption configuration
     * @param {'append'|'override'} [exportParam.mode] (optional) set writing mode
     * @param {import("./defs/types").DebugTypes} [exportParam.debug] (optional) set debug mode
     * @returns {Promise<{success: boolean, message?: string, error?: *}>} Promise resolving with two parameters: boolean 'success' and either 'error' or 'result'
     * @static
     * @memberof UnSQL
     */
    static async export({ target = this?.config?.table, directory = 'exports_unsql', select = ['*'], alias = undefined, join = [], where = {}, groupBy = [], having = {}, orderBy = {}, limit = undefined, offset = undefined, encrypt = undefined, encryption = undefined, mode = 'append', debug = false } = {}) {

        patchDefaults(this)
        const defaultResp = handleDefaults(this)

        if (!defaultResp.success) return defaultResp
        if (!this?.config?.devMode) return { success: false, error: `[Action Denied]: Record(s) can only be exported from '${this?.name}' model if inside 'config', 'devMode' is set to 'true' (currently '${this?.config?.devMode}')` }
        if (Object.getPrototypeOf(target) === UnSQL && !target['config']?.devMode) return { success: false, error: `[Action Denied]: Record(s) can only be exported from '${target['name']}' model if inside 'config', 'devMode' is set to 'true' (currently '${target['config']?.devMode}')` }

        const result = await this.find({ alias, select, join, where, groupBy, having, orderBy, limit, offset, debug, encryption })

        if (!result.success) {
            console.error(colors.red, result.error?.sqlMessage || result.error?.message, colors.reset)
            return result
        }

        switch (true) {

            case (Object.getPrototypeOf(target) === UnSQL): { // export to 'model' class
                const cloned = await target['save']({ data: result.result, encrypt, encryption, debug })
                if (!cloned.success) {
                    console.error(colors.red, cloned.error?.sqlMessage || cloned.error?.message, colors.reset)
                    return cloned
                }
                return { success: true, message: `${result?.result?.length} records exported to '${target['name']}' model` }
            }

            case typeof target === 'string': { // export to '.json' file
                const path = require('path')
                const dir = path.join(path.dirname(require.main?.filename || ''), directory)

                const fs = require('fs/promises')
                await fs.mkdir(dir, { recursive: true })

                if (mode === 'override')
                    await fs.writeFile(path.join(dir, `${target}.json`), JSON.stringify(result.result))
                else
                    await fs.appendFile(path.join(dir, `${target}.json`), JSON.stringify(result.result))

                return { success: true, message: `${result?.result?.length} records exported from '${this?.name}' model into '${directory}/${target}.json' file` }
            }

            default:
                return { success: false, error: "Invalid Input! 'target' property can either be 'string' or a valid UnSQL model class" }
        }

    }

    /**
     * Will reset the database table to initial state
     * @method reset
     * @param {Object} resetParam
     * @param {import("./defs/types").DebugTypes} [resetParam.debug] (optional) set debug mode
     * @returns {Promise<{success:boolean, message?:string, result?:*, error?:*}>} Promise resolving with two parameters: boolean 'success' and either 'error' or 'result'
     * @static
     * @memberof UnSQL
     */
    static async reset({ debug = false } = {}) {

        patchDefaults(this)

        const defaultResp = handleDefaults(this)

        if (!defaultResp.success) return defaultResp

        const sql = `TRUNCATE ${this?.isMySQL ? '??' : `"${this.config?.table}"`}`
        const values = []

        if (this.isMySQL) values.push(this.config.table)

        const debugMessage = `Reset '${this?.config?.table}' table record(s) in`
        return await handleExecutions[this.config.dialect]({ sql, values, debug, config: this?.config, debugMessage })
    }

}

/**
 * @function executeMySQL
 * @description executes the SQL query
 * @param {Object} options
 * @param {string} options.sql SQL query to be executed
 * @param {Array<any>} options.values values to be interpolated in the query
 * @param {import("./defs/types").DebugTypes} [options.debug] enables debug mode
 * @param {Object} [options.session] global session reference for transactions and rollback
 * @param {Object} [options.config] global configuration object
 * @param {string} [options.debugMessage] debug message to be displayed in console
 * @param {boolean} [options.multiQuery] flag if sql contains multiple queries (only in 'mysql'), default is false
 * @param {import("./defs/types").EncryptionConfig} [options.encryption] enables encryption
 * @returns {Promise<{success:false, error:*}|{success:true, result:*, meta?:*}>} Promise resolving with two parameters: boolean 'success' and either 'error' or 'results'
 */
const executeMySQL = async ({ sql, values, debug = false, session = undefined, config, encryption = undefined, multiQuery = false, debugMessage = '' }) => {
    const connection = await (session?.connection || config?.pool?.getConnection() || config?.connection)
    const isDebugging = debug === 'benchmark' || debug === 'benchmark-query' || debug === 'benchmark-error' || debug === true
    try {
        const statement = await connection.format(sql, values)
        handleQueryDebug(debug, sql, values, statement)
        if (!session) await connection?.beginTransaction()
        if ((encryption?.mode && encryption?.mode != config?.dbEncryptionMode) || (config?.encryption?.mode && config?.encryption?.mode != config?.dbEncryptionMode)) {
            try {
                const [encResp] = await connection.execute('SET block_encryption_mode = ?', [encryption?.mode || config?.encryption?.mode])
            } catch (error) {
                throw { message: `[Error]: ${error?.message} `, cause: `While setting encryption mode to: '${encryption?.mode || config?.encryption?.mode}'` }
            }
        }
        if (isDebugging) console.time(`${colors.blue}UnSQL benchmark:${colors.reset} ${colors.cyan}${debugMessage}${colors.reset}`)
        const [result, meta] = await connection[multiQuery ? 'query' : 'execute'](statement)
        if (!session) await connection?.commit()
        if (isDebugging) console.timeEnd(`${colors.blue}UnSQL benchmark:${colors.reset} ${colors.cyan}${debugMessage}${colors.reset}`)
        return { success: true, result, meta }
    } catch (error) {
        handleError(debug, error)
        if (connection && !session) await connection?.rollback()
        return { success: false, error }
    } finally {
        if (config?.pool && !session) await connection?.release()
    }
}

/**
 * patch defaults to config context
 * @function patchDefaults
 * @description patches default values to config context
 * @param {object} options 
 * @returns {Promise<{success:true, result:*}|{success:false, error:*}>} Promise resolving with two parameters: boolean 'success' and either 'error' or 'result'
 * @author Siddharth Tiwari <dev.unsql@gmail.com>
 */
const executePostgreSQL = async ({ sql, values, debug = false, config, session = undefined, debugMessage = '' }) => {
    const client = await (session?.connection || config?.pool?.connect())
    const isBenchmarking = debug === 'benchmark' || debug === 'benchmark-query' || debug === 'benchmark-error' || debug === true
    handleQueryDebug(debug, sql, values)
    try {
        if (!session) await client.query('BEGIN')
        if (isBenchmarking) console.time(`${colors.blue}UnSQL benchmark:${colors.reset} ${colors.cyan}${debugMessage}${colors.reset}`)
        const result = await client.query(sql, values)
        if (!session) await client.query('COMMIT')

        const payload = []
        const meta = []

        if (Array.isArray(result)) {
            for (let i = 0; i < result.length; i++) {
                const { rows, fields } = result[i]
                if (rows && rows.length) {
                    payload.push(...rows)
                    meta.push(fields)
                } else if (fields && fields.length) {
                    meta.push(fields)
                }
            }
        } else {
            payload.push(...result.rows)
            meta.push(result.fields)
        }
        if (isBenchmarking) console.timeEnd(`${colors.blue}UnSQL benchmark:${colors.reset} ${colors.cyan}${debugMessage}${colors.reset}`)
        return { success: true, result: payload }
    } catch (error) {
        if (!session) await client.query('ROLLBACK')
        handleError(debug, error)
        return { success: false, error: { ...error, message: error.message } }
    } finally {
        if (!session) await client.release()
    }
}

/**
 * executes sqlite queries
 * @function executeSqlite
 * @param {Object} options
 * @param {string} options.sql
 * @param {Array} options.values
 * @param {import("./defs/types").DebugTypes} [options.debug]
 * @param {import("./defs/types").ConfigObject} [options.config]
 * @param {'all'|'run'|'exec'} [options.methodType=all]
 * @param {string} [options.debugMessage]
 * @param {*} [options.session]
 * @returns {Promise<{success:boolean, result?:Array, insertId?:number, changes?:number, error?:*}>}
 */
async function executeSqlite({ sql, values, debug = false, config, methodType = 'all', session = undefined, debugMessage = '' }) {
    const db = await (session?.pool || config?.pool)
    handleQueryDebug(debug, sql, values)
    const isBenchmarking = debug === 'benchmark' || debug === 'benchmark-query' || debug === 'benchmark-error' || debug === true
    if (typeof db[methodType] != 'function') return { success: false, error: `Invalid method '${methodType}' detected!` }
    try {
        if (!session?.pool) await db.run('BEGIN TRANSACTION')
        if (isBenchmarking) console.time(`${colors.blue}UnSQL benchmark:${colors.reset} ${colors.cyan}${debugMessage}${colors.reset}`)
        const result = await db[methodType](sql, values) // execute query
        if (!session?.pool) await db.run('COMMIT')
        if (isBenchmarking) console.timeEnd(`${colors.blue}UnSQL benchmark:${colors.reset} ${colors.cyan}${debugMessage}${colors.reset}`)
        return {
            success: true,
            ...(methodType === 'all' && { result }),
            ...('lastID' in result && { insertId: result?.lastID }),
            ...('changes' in result && { changes: result?.changes })
        }
    } catch (error) {
        if (!session?.pool) await db.run('ROLLBACK')
        return { success: false, error: { ...error, message: error.message } }
    }
}

/**
 * patch defaults to config context
 * @function patchDefaults
 * @description patches default values to config context
 * @param {object} ctx 
 * @returns {void}
 * @author Siddharth Tiwari <dev.unsql@gmail.com>
 */
const patchDefaults = ctx => {
    if (!('devMode' in ctx.config)) ctx.config.devMode = false
    if (!('safeMode' in ctx.config)) ctx.config.safeMode = true
    if (!('dialect' in ctx.config)) ctx.config.dialect = 'mysql'
    if (!('dbEncryptionMode' in ctx.config)) ctx.config.dbEncryptionMode = 'unknown'
    ctx._variableCount = 1
    ctx.isMySQL = ctx?.config?.dialect === 'mysql'
    ctx.isPostgreSQL = ctx?.config?.dialect === 'postgresql'
    ctx.isSQLite = ctx?.config?.dialect === 'sqlite'
}

const handleDefaults = ctx => {
    if (!ctx?.config && ('TABLE_NAME' in ctx) && ('POOL' in ctx)) return { success: false, error: `[UnSQL Version Conflict]: '${ctx?.name}' model class is using 'v1.x' class configuration with 'v2.x' to continue with 'v1.x' kindly switch the 'unsql' import to 'unsql/legacy'` }
    // handle if connection object is missing
    if (!ctx?.config?.pool && !ctx?.config?.connection) return { success: false, error: `[Missing]: Please provide${ctx?.isMySQL ? ` 'connection' or` : ''} 'pool' inside config(static property) of '${ctx?.name}' model class` }
    // handle if table name is missing
    if (!ctx?.config?.table) return { success: false, error: `[Required]: Missing 'table' name inside 'config' of '${ctx?.name}' model class` }
    return { success: true }
}

const handleExecutions = {
    mysql: executeMySQL,
    postgresql: executePostgreSQL,
    sqlite: executeSqlite
}

const prepJsonbUpdate = (col, value, isUpdate) => isUpdate ? `${col}:: jsonb || '${JSON.stringify(value)}':: jsonb` : `'${JSON.stringify(value)}':: jsonb`

/**
 * @class
 * @description provides various lifecycle methods to manage re-usable MySQL session (transactions)
 * @alias SessionManager
 * 
 * @returns {Promise<{success: boolean, error?: string, message?: string}>} Promise resolving with two parameters: boolean 'success' and either 'error' or 'message'
 * @author Siddharth Tiwari <dev.unsql@gmail.com>
 */
class SessionManager {

    /**
     * @constructor
     * @param {*} pool MySQL connection pool or connection object or PostgreSQL pool object
     * @param {'mysql'|'postgresql'|'sqlite'} [dialect='mysql'] 
     */
    constructor(pool, dialect = 'mysql') {
        this.pool = pool
        this.dialect = dialect
    }

    /**
     * @async
     * @method init
     * @description initiates transaction
     * @returns {Promise<void|{success: false, error?: *}|{success: true, message: string}>}
     * @memberof SessionManager
     */
    async init() {
        switch (this?.dialect) {
            case 'mysql':
                this.connection = await this?.pool?.getConnection() || this?.pool
                await this?.connection?.beginTransaction()
                break
            case 'postgresql':
                this.connection = await this?.pool?.connect()
                await this?.connection?.query('BEGIN')
                break
            case 'sqlite':
                this.connection = await this?.pool
                await this?.connection?.run('BEGIN')
                break
            default:
                return { success: false, error: 'Invalid dialect provided in config' }
        }
        return { success: true, message: 'Transaction initialized successfully!' }
    }

    /**
     * @async
     * @method rollback
     * @description rollbacks the changes, if 'false' is passed then session will not be closed
     * @param {boolean} [close=true]
     * @returns {Promise<void>}
     * @memberof SessionManager
     */
    async rollback(close = true) {
        if (this.dialect === 'mysql') await this?.connection?.rollback()
        else if (this.dialect === 'postgresql') await this?.connection?.query('ROLLBACK')
        else if (this.dialect === 'sqlite') await this?.connection?.run('ROLLBACK')
        if (close) await this.close()
    }

    /**
     * @async
     * @method commit
     * @description commits the changes, if 'false' is passed then session will not be closed
     * @param {boolean} [close=true]
     * @returns {Promise<void|{success: false, error: string}>}
     * @memberof SessionManager
    */
    async commit(close = true) {
        try {
            if (this.dialect === 'mysql') await this.connection.commit()
            else if (this.dialect === 'postgresql') await this.connection.query('COMMIT')
            else if (this.dialect === 'sqlite') await this.connection.run('COMMIT')
        } catch (error) {
            await this.rollback()
            return { success: false, error }
        } finally {
            if (close) await this.close()
        }
    }

    /**
     * @async
     * @method close
     * @description terminates the session and releases the connection
     * @returns {Promise<void>}
     * @memberof SessionManager
     */
    async close() {
        if (typeof this?.connection?.release === 'function') await this.connection?.release()
        delete this.connection
    }
}

module.exports = { UnSQL, SessionManager }
module.exports.default = UnSQL