#!/bin/bash

# Copyright © 2012-2026 ScriptFanix
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# A copy of the GNU General Public License v3 is includded in the LICENSE file
# at the root of the project.

Update() {
#Update table set_key set_value [set_key set_value […]] <	where_key where_operator where_value
#								[where_key where_operator where_value
#								[…]]
	local			\
		table="$1"	\
		key		\
		argument	\
		operator	\
		value		\
		set_statement	\
		where_keys	\
		where_values	\
		what		\
		where_statement	\
		results
	shift
	# Parse positional args as alternating key/value for the SET clause
	what=key
	for argument
	do
		case $what in
			key)
				# Backtick-quote column name to handle reserved
				# words
				set_statement="${set_statement:+${set_statement},}\`$argument\`"
				what=value
			;;
			value)
				case $argument in
					'::AtOM:FT::'*)
						# Force-text: strip prefix and
						# quote as string
						argument="${argument//::AtOM:FT::/}"
						set_statement+=" = "'"'"${argument//\"/\"\"}"'"'
					;;
					'NULL')
						set_statement+=" = NULL"
					;;
					+([0-9])?(.+([0-9])))
						# Numeric value: store unquoted
						set_statement+=" = $argument"
					;;
					*)
						set_statement+=" = "'"'"${argument//\"/\"\"}"'"'
					;;
				esac
				what=key
			;;
		esac
	done
	# Build WHERE clause from stdin
	while read key operator value
	do
		(( ${#where_statement} )) && where_statement+=( "AND" )
		case $value in
			'NULL')
				where_statement+=( "$key is NULL" )
			;;
			+([0-9.]))
				# Numeric: compare without quotes
				where_statement+=( "$key $operator $value" )
			;;
			*)
				where_statement+=( "$key $operator "'"'"${value//\"/\"\"}"'"' )
			;;
		esac
	done
	echo	"UPDATE '$table' SET"		\
			"$set_statement"	\
		"WHERE"				\
			"${where_statement[@]}"	\
		";" >&3
}