/*
   GoUtils - a library to assist with various Golang-related functions
   Copyright (C) 2020  Brent Saner

   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, or
   (at your option) any later version.

   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.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

package structutils

import (
	`reflect`
	`strings`
)

/*
	TagToBoolMap takes struct field `field` and tag name `tagName`,
	 optionally with options `opts`, and returns a map of the tag values.
	The tag value string is assumed to be in the form of:
		option[,option,option...]
	and returns a map[string]bool (map[option]true).

	If field does not have tag tagName, m will be nil.

	See the TagMap* constants for opts.
*/
func TagToBoolMap(field reflect.StructField, tagName string, opts ...tagMapOpt) (m map[string]bool) {

	var s string
	var optSplit []string
	var tagOpts map[tagMapOpt]bool = getTagMapOpts(opts)

	s = field.Tag.Get(tagName)

	if strings.TrimSpace(s) == "" {
		return
	}

	optSplit = strings.Split(s, ",")
	if optSplit == nil || len(optSplit) == 0 {
		return
	}
	m = make(map[string]bool)
	for _, o := range optSplit {
		if tagOpts[TagMapTrim] {
			o = strings.TrimSpace(o)
		}
		m[o] = true
	}

	return
}

/*
	TagToBoolMapWithValue is like TagToBoolMap but additionally assumes the first value is an "identifier".
	The tag value string is assumed to be in the form of:
		value,option[,option,option...]
	and returns a map[string]bool (map[option]true) with the value.
*/
func TagToBoolMapWithValue(field reflect.StructField, tagName string, opts ...tagMapOpt) (value string, m map[string]bool) {

	var s string
	var optSplit []string
	var tagOpts map[tagMapOpt]bool = getTagMapOpts(opts)

	s = field.Tag.Get(tagName)

	if strings.TrimSpace(s) == "" {
		return
	}

	optSplit = strings.Split(s, ",")
	if optSplit == nil || len(optSplit) == 0 {
		return
	}
	m = make(map[string]bool)
	for idx, o := range optSplit {
		if idx == 0 {
			if tagOpts[TagMapTrim] {
				o = strings.TrimSpace(o)
			}
			value = o
			continue
		}
		if tagOpts[TagMapTrim] {
			o = strings.TrimSpace(o)
		}
		m[o] = true
	}

	return
}

/*
	TagToMixedMap combines TagToBoolMap and TagToStringMap.
	It takes struct field `field` and tag name `tagName`,
	and returns all single-value options in mapBool, and all key/value options in mapString.

	If field does not have tag tagName, m will be nil.

	See the TagMap* constants for opts.
*/
func TagToMixedMap(field reflect.StructField, tagName string, opts ...tagMapOpt) (mapBool map[string]bool, mapString map[string]string) {

	var s string
	var valStr string
	var split []string
	var kvSplit []string
	var valSplit []string
	var k string
	var v string
	var tagOpts map[tagMapOpt]bool = getTagMapOpts(opts)

	s = field.Tag.Get(tagName)

	if strings.TrimSpace(s) == "" {
		return
	}

	split = strings.Split(s, ",")
	if split == nil || len(split) == 0 {
		return
	}
	mapBool = make(map[string]bool)
	mapString = make(map[string]string)
	for _, valStr = range split {
		if strings.Contains(valStr, "=") {
			kvSplit = strings.SplitN(valStr, "=", 2)
			if kvSplit == nil || len(kvSplit) == 0 {
				continue
			}
			k = valSplit[0]
			switch len(valSplit) {
			case 1:
				v = ""
			case 2:
				v = kvSplit[1]
			}
			if tagOpts[TagMapTrim] {
				k = strings.TrimSpace(k)
				v = strings.TrimSpace(v)
			}
			mapString[k] = v
		} else {
			if tagOpts[TagMapTrim] {
				valStr = strings.TrimSpace(valStr)
			}
			mapBool[valStr] = true
		}
	}

	return
}

/*
	TagToMixedMapWithValue combines TagToBoolMapWithValue and TagToStringMapWithValue.
	It takes struct field `field` and tag name `tagName`,
	and returns all single-value options in mapBool, and all key/value options in mapString
	along with the first single-value option as value..

	If field does not have tag tagName, m will be nil.

	See the TagMap* constants for opts.
*/
func TagToMixedMapWithValue(field reflect.StructField, tagName string, opts ...tagMapOpt) (value string, mapBool map[string]bool, mapString map[string]string) {

	var s string
	var idx int
	var valStr string
	var split []string
	var kvSplit []string
	var valSplit []string
	var k string
	var v string
	var tagOpts map[tagMapOpt]bool = getTagMapOpts(opts)

	s = field.Tag.Get(tagName)

	if strings.TrimSpace(s) == "" {
		return
	}

	split = strings.Split(s, ",")
	if split == nil || len(split) == 0 {
		return
	}
	mapBool = make(map[string]bool)
	mapString = make(map[string]string)
	for idx, valStr = range split {
		if idx == 0 {
			if tagOpts[TagMapTrim] {
				valStr = strings.TrimSpace(valStr)
			}
			value = valStr
			continue
		}
		if strings.Contains(valStr, "=") {
			kvSplit = strings.SplitN(valStr, "=", 2)
			if kvSplit == nil || len(kvSplit) == 0 {
				continue
			}
			k = valSplit[0]
			switch len(valSplit) {
			case 1:
				v = ""
			case 2:
				v = kvSplit[1]
			}
			if tagOpts[TagMapTrim] {
				k = strings.TrimSpace(k)
				v = strings.TrimSpace(v)
			}
			mapString[k] = v
		} else {
			if tagOpts[TagMapTrim] {
				valStr = strings.TrimSpace(valStr)
			}
			mapBool[valStr] = true
		}
	}

	return
}

/*
	TagToStringMap takes struct field `field` and tag name `tagName`,
	 optionally with options `opts`, and returns a map of the tag values.
	The tag value string is assumed to be in the form of:
		key=value[,key=value,key=value...]
	and returns a map[string]string (map[key]value).
	It is proccessed in order; later duplicate keys overwrite previous ones.

	If field does not have tag tagName, m will be nil.

	If only a key is provided with no value, the value in the map will be an empty string.
	(e.g. "foo,bar=baz" => map[string]string{"foo": "", "bar: "baz"}

	See the TagMap* constants for opts.
*/
func TagToStringMap(field reflect.StructField, tagName string, opts ...tagMapOpt) (m map[string]string) {

	var s string
	var kvSplit []string
	var valSplit []string
	var k string
	var v string
	var tagOpts map[tagMapOpt]bool = getTagMapOpts(opts)

	s = field.Tag.Get(tagName)

	if strings.TrimSpace(s) == "" {
		return
	}

	kvSplit = strings.Split(s, ",")
	if kvSplit == nil || len(kvSplit) == 0 {
		return
	}
	for _, kv := range kvSplit {
		valSplit = strings.SplitN(kv, "=", 2)
		if valSplit == nil || len(valSplit) == 0 {
			continue
		}
		k = valSplit[0]
		switch len(valSplit) {
		case 1:
			v = ""
		case 2:
			v = valSplit[1]
			// It's not possible to have more than 2.
		}
		if m == nil {
			m = make(map[string]string)
		}
		if tagOpts[TagMapTrim] {
			k = strings.TrimSpace(k)
			v = strings.TrimSpace(v)
		}
		m[k] = v
	}

	return
}

/*
	TagToStringMapWithValue is like TagToStringMap but additionally assumes the first value is an "identifier".
	The tag value string is assumed to be in the form of:
		value,key=value[,key=value,key=value...]
	and returns a map[string]string (map[key]value) with the value.
*/
func TagToStringMapWithValue(field reflect.StructField, tagName string, opts ...tagMapOpt) (value string, m map[string]string) {

	var s string
	var kvSplit []string
	var valSplit []string
	var k string
	var v string
	var tagOpts map[tagMapOpt]bool = getTagMapOpts(opts)

	s = field.Tag.Get(tagName)

	if strings.TrimSpace(s) == "" {
		return
	}

	kvSplit = strings.Split(s, ",")
	if kvSplit == nil || len(kvSplit) == 0 {
		return
	}
	for idx, kv := range kvSplit {
		if idx == 0 {
			if tagOpts[TagMapTrim] {
				kv = strings.TrimSpace(kv)
			}
			value = kv
			continue
		}
		valSplit = strings.SplitN(kv, "=", 2)
		if valSplit == nil || len(valSplit) == 0 {
			continue
		}
		k = valSplit[0]
		switch len(valSplit) {
		case 1:
			v = ""
		case 2:
			v = valSplit[1]
			// It's not possible to have more than 2.
		}
		if m == nil {
			m = make(map[string]string)
		}
		if tagOpts[TagMapTrim] {
			k = strings.TrimSpace(k)
			v = strings.TrimSpace(v)
		}
		m[k] = v
	}

	return
}

func getTagMapOpts(opts []tagMapOpt) (optMap map[tagMapOpt]bool) {

	optMap = make(map[tagMapOpt]bool)

	if opts == nil {
		return
	}

	return
}