import { hasVal, toUpper } from './util'

import { exprToSQL, orderOrPartitionByToSQL } from './expr'

import { overToSQL } from './over'

function windowSpecificationToSQL(windowSpec) {

const {

name,

partitionby,

orderby,

window_frame_clause: windowFrame,

} = windowSpec

const result = [

name,

orderOrPartitionByToSQL(partitionby, 'partition by'),

orderOrPartitionByToSQL(orderby, 'order by'),

toUpper(windowFrame),

]

return result.filter(hasVal).join(' ')

}

function asWindowSpecToSQL(asWindowSpec) {

if (typeof asWindowSpec === 'string') return asWindowSpec

const { window_specification: windowSpec } = asWindowSpec

return `(${windowSpecificationToSQL(windowSpec)})`

}

function namedWindowExprToSQL(namedWindowExpr) {

const { name, as_window_specification: asWindowSpec } = namedWindowExpr

return `${name} AS ${asWindowSpecToSQL(asWindowSpec)}`

}

function namedWindowExprListToSQL(namedWindowExprInfo) {

const { expr } = namedWindowExprInfo

return expr.map(namedWindowExprToSQL).join(', ')

}

function isConsiderNullsInArgs(fnName) {

// position of IGNORE/RESPECT NULLS varies by function

switch (fnName) {

case 'NTH_VALUE':

case 'LEAD':

case 'LAG':

return false

default:

return true

}

}

function constructArgsList(expr) {

const { args, name, consider_nulls = '' } = expr

const argsList = args ? exprToSQL(args).join(', ') : ''

// cover Syntax from FN_NAME(...args [RESPECT NULLS]) [RESPECT NULLS]

const isConsidernulls = isConsiderNullsInArgs(name)

const result = [name, '(', argsList, !isConsidernulls && ')', consider_nulls && ' ', consider_nulls, isConsidernulls && ')']

return result.filter(hasVal).join('')

}

function windowFuncToSQL(expr) {

const { over } = expr

const str = constructArgsList(expr)

const overStr = overToSQL(over)

return [str, overStr].filter(hasVal).join(' ')

}

export {

asWindowSpecToSQL,

namedWindowExprToSQL,

namedWindowExprListToSQL,

windowFuncToSQL,

windowSpecificationToSQL,

}