package main

import (
	"bytes"
	"fmt"
	"go/format"
	"io/ioutil"
	"path/filepath"
	"runtime"
	"strings"
	"text/template"
)

type opType struct {
	Op                    string
	Code                  string
	HeadToPtrHead         func() string
	HeadToNPtrHead        func() string
	HeadToAnonymousHead   func() string
	HeadToOmitEmptyHead   func() string
	HeadToStringTagHead   func() string
	HeadToOnlyHead        func() string
	PtrHeadToHead         func() string
	FieldToEnd            func() string
	FieldToOmitEmptyField func() string
	FieldToStringTagField func() string
}

func (t opType) IsHeadToPtrHead() bool {
	return t.Op != t.HeadToPtrHead()
}

func (t opType) IsHeadToNPtrHead() bool {
	return t.Op != t.HeadToNPtrHead()
}

func (t opType) IsHeadToAnonymousHead() bool {
	return t.Op != t.HeadToAnonymousHead()
}

func (t opType) IsHeadToOmitEmptyHead() bool {
	return t.Op != t.HeadToOmitEmptyHead()
}

func (t opType) IsHeadToStringTagHead() bool {
	return t.Op != t.HeadToStringTagHead()
}

func (t opType) IsPtrHeadToHead() bool {
	return t.Op != t.PtrHeadToHead()
}

func (t opType) IsHeadToOnlyHead() bool {
	return t.Op != t.HeadToOnlyHead()
}

func (t opType) IsFieldToEnd() bool {
	return t.Op != t.FieldToEnd()
}

func (t opType) IsFieldToOmitEmptyField() bool {
	return t.Op != t.FieldToOmitEmptyField()
}

func (t opType) IsFieldToStringTagField() bool {
	return t.Op != t.FieldToStringTagField()
}

func createOpType(op, code string) opType {
	return opType{
		Op:                    op,
		Code:                  code,
		HeadToPtrHead:         func() string { return op },
		HeadToNPtrHead:        func() string { return op },
		HeadToAnonymousHead:   func() string { return op },
		HeadToOmitEmptyHead:   func() string { return op },
		HeadToStringTagHead:   func() string { return op },
		HeadToOnlyHead:        func() string { return op },
		PtrHeadToHead:         func() string { return op },
		FieldToEnd:            func() string { return op },
		FieldToOmitEmptyField: func() string { return op },
		FieldToStringTagField: func() string { return op },
	}
}

func _main() error {
	tmpl, err := template.New("").Parse(`// Code generated by cmd/generator. DO NOT EDIT!
package json

import (
  "strings"
)

type codeType int

const (
{{- range $index, $type := .CodeTypes }}
  code{{ $type }} codeType = {{ $index }}
{{- end }}
)

var opTypeStrings = [{{ .OpLen }}]string{
{{- range $type := .OpTypes }}
    "{{ $type.Op }}",
{{- end }}
}

type opType int

const (
{{- range $index, $type := .OpTypes }}
  op{{ $type.Op }} opType = {{ $index }}
{{- end }}
)

func (t opType) String() string {
  if int(t) >= {{ .OpLen }} {
    return ""
  }
  return opTypeStrings[int(t)]
}

func (t opType) codeType() codeType {
  if strings.Contains(t.String(), "Struct") {
    if strings.Contains(t.String(), "End") {
      return codeStructEnd
    }
    return codeStructField
  }
  if strings.Contains(t.String(), "ArrayHead") {
    return codeArrayHead
  }
  if strings.Contains(t.String(), "ArrayElem") {
    return codeArrayElem
  }
  if strings.Contains(t.String(), "SliceHead") {
    return codeSliceHead
  }
  if strings.Contains(t.String(), "SliceElem") {
    return codeSliceElem
  }
  if strings.Contains(t.String(), "MapHead") {
    return codeMapHead
  }
  if strings.Contains(t.String(), "MapKey") {
    return codeMapKey
  }
  if strings.Contains(t.String(), "MapValue") {
    return codeMapValue
  }
  if strings.Contains(t.String(), "MapEnd") {
    return codeMapEnd
  }

  return codeOp
}

func (t opType) headToPtrHead() opType {
  if strings.Index(t.String(), "PtrHead") > 0 {
    return t
  }
  if strings.Index(t.String(), "PtrAnonymousHead") > 0 {
    return t
  }

  idx := strings.Index(t.String(), "Field")
  if idx == -1 {
    return t
  }
  suffix := "Ptr"+t.String()[idx+len("Field"):]

  const toPtrOffset = 12
  if strings.Contains(opType(int(t) + toPtrOffset).String(), suffix) {
    return opType(int(t) + toPtrOffset)
  }
  return t
}

func (t opType) headToNPtrHead() opType {
  if strings.Index(t.String(), "PtrHead") > 0 {
    return t
  }
  if strings.Index(t.String(), "PtrAnonymousHead") > 0 {
    return t
  }

  idx := strings.Index(t.String(), "Field")
  if idx == -1 {
    return t
  }
  suffix := "NPtr"+t.String()[idx+len("Field"):]

  const toPtrOffset = 24
  if strings.Contains(opType(int(t) + toPtrOffset).String(), suffix) {
    return opType(int(t) + toPtrOffset)
  }
  return t
}

func (t opType) headToAnonymousHead() opType {
  const toAnonymousOffset = 6
  if strings.Contains(opType(int(t) + toAnonymousOffset).String(), "Anonymous") {
    return opType(int(t) + toAnonymousOffset)
  }
  return t
}

func (t opType) headToOmitEmptyHead() opType {
  const toOmitEmptyOffset = 2
  if strings.Contains(opType(int(t) + toOmitEmptyOffset).String(), "OmitEmpty") {
    return opType(int(t) + toOmitEmptyOffset)
  }

  return t
}

func (t opType) headToStringTagHead() opType {
  const toStringTagOffset = 4
  if strings.Contains(opType(int(t) + toStringTagOffset).String(), "StringTag") {
    return opType(int(t) + toStringTagOffset)
  }
  return t
}

func (t opType) headToOnlyHead() opType {
  if strings.HasSuffix(t.String(), "Head") || strings.HasSuffix(t.String(), "HeadOmitEmpty") || strings.HasSuffix(t.String(), "HeadStringTag") {
    return t
  }

  const toOnlyOffset = 1
  if opType(int(t) + toOnlyOffset).String() == t.String() + "Only" {
    return opType(int(t) + toOnlyOffset)
  }
  return t
}

func (t opType) ptrHeadToHead() opType {
  idx := strings.Index(t.String(), "Ptr")
  if idx == -1 {
    return t
  }
  suffix := t.String()[idx+len("Ptr"):]

  const toPtrOffset = 12
  if strings.Contains(opType(int(t) - toPtrOffset).String(), suffix) {
    return opType(int(t) - toPtrOffset)
  }
  return t
}

func (t opType) fieldToEnd() opType {
  switch t {
{{- range $type := .OpTypes }}
{{- if $type.IsFieldToEnd }}
  case op{{ $type.Op }}:
    return op{{ call $type.FieldToEnd }}
{{- end }}
{{- end }}
  }
  return t
}

func (t opType) fieldToOmitEmptyField() opType {
  const toOmitEmptyOffset = 1
  if strings.Contains(opType(int(t) + toOmitEmptyOffset).String(), "OmitEmpty") {
    return opType(int(t) + toOmitEmptyOffset)
  }
  return t
}

func (t opType) fieldToStringTagField() opType {
  const toStringTagOffset = 2
  if strings.Contains(opType(int(t) + toStringTagOffset).String(), "StringTag") {
    return opType(int(t) + toStringTagOffset)
  }
  return t
}

`)
	if err != nil {
		return err
	}
	codeTypes := []string{
		"Op",
		"ArrayHead",
		"ArrayElem",
		"SliceHead",
		"SliceElem",
		"MapHead",
		"MapKey",
		"MapValue",
		"MapEnd",
		"StructFieldRecursive",
		"StructField",
		"StructEnd",
	}
	primitiveTypes := []string{
		"int", "uint", "float32", "float64", "bool", "string", "bytes",
		"array", "map", "mapLoad", "slice", "struct", "MarshalJSON", "MarshalText", "recursive",
		"intString", "uintString",
		"intPtr", "uintPtr", "float32Ptr", "float64Ptr", "boolPtr", "stringPtr", "bytesPtr",
		"intNPtr", "uintNPtr", "float32NPtr", "float64NPtr", "boolNPtr", "stringNPtr", "bytesNPtr",
	}
	primitiveTypesUpper := []string{}
	for _, typ := range primitiveTypes {
		primitiveTypesUpper = append(primitiveTypesUpper, strings.ToUpper(string(typ[0]))+typ[1:])
	}
	opTypes := []opType{
		createOpType("End", "Op"),
		createOpType("Interface", "Op"),
		createOpType("Ptr", "Op"),
		createOpType("NPtr", "Op"),
		createOpType("SliceHead", "SliceHead"),
		createOpType("RootSliceHead", "SliceHead"),
		createOpType("SliceElem", "SliceElem"),
		createOpType("RootSliceElem", "SliceElem"),
		createOpType("SliceEnd", "Op"),
		createOpType("ArrayHead", "ArrayHead"),
		createOpType("ArrayElem", "ArrayElem"),
		createOpType("ArrayEnd", "Op"),
		createOpType("MapHead", "MapHead"),
		createOpType("MapHeadLoad", "MapHead"),
		createOpType("MapKey", "MapKey"),
		createOpType("MapValue", "MapValue"),
		createOpType("MapEnd", "Op"),
		createOpType("StructFieldRecursiveEnd", "Op"),
		createOpType("StructAnonymousEnd", "StructEnd"),
	}
	for _, typ := range primitiveTypesUpper {
		typ := typ
		opTypes = append(opTypes, createOpType(typ, "Op"))
	}
	for _, typ := range append(primitiveTypesUpper, "") {
		for _, ptrOrNot := range []string{"", "Ptr", "NPtr"} {
			for _, headType := range []string{"", "Anonymous"} {
				for _, opt := range []string{"", "OmitEmpty", "StringTag"} {
					for _, onlyOrNot := range []string{"", "Only"} {
						ptrOrNot := ptrOrNot
						headType := headType
						opt := opt
						typ := typ
						onlyOrNot := onlyOrNot

						op := fmt.Sprintf(
							"StructField%s%sHead%s%s%s",
							ptrOrNot,
							headType,
							opt,
							typ,
							onlyOrNot,
						)
						opTypes = append(opTypes, opType{
							Op:   op,
							Code: "StructField",
							HeadToPtrHead: func() string {
								return fmt.Sprintf(
									"StructFieldPtr%sHead%s%s%s",
									headType,
									opt,
									typ,
									onlyOrNot,
								)
							},
							HeadToNPtrHead: func() string {
								return fmt.Sprintf(
									"StructFieldNPtr%sHead%s%s%s",
									headType,
									opt,
									typ,
									onlyOrNot,
								)
							},
							HeadToAnonymousHead: func() string {
								return fmt.Sprintf(
									"StructField%sAnonymousHead%s%s%s",
									ptrOrNot,
									opt,
									typ,
									onlyOrNot,
								)
							},
							HeadToOmitEmptyHead: func() string {
								return fmt.Sprintf(
									"StructField%s%sHeadOmitEmpty%s%s",
									ptrOrNot,
									headType,
									typ,
									onlyOrNot,
								)
							},
							HeadToStringTagHead: func() string {
								return fmt.Sprintf(
									"StructField%s%sHeadStringTag%s%s",
									ptrOrNot,
									headType,
									typ,
									onlyOrNot,
								)
							},
							HeadToOnlyHead: func() string {
								switch typ {
								case "", "Array", "Map", "MapLoad", "Slice",
									"Struct", "Recursive", "MarshalJSON", "MarshalText",
									"IntString", "UintString":
									return op
								}
								return fmt.Sprintf(
									"StructField%s%sHead%s%sOnly",
									ptrOrNot,
									headType,
									opt,
									typ,
								)
							},
							PtrHeadToHead: func() string {
								return fmt.Sprintf(
									"StructField%sHead%s%s%s",
									headType,
									opt,
									typ,
									onlyOrNot,
								)
							},
							FieldToEnd:            func() string { return op },
							FieldToOmitEmptyField: func() string { return op },
							FieldToStringTagField: func() string { return op },
						})
					}
				}
			}
		}
	}
	for _, typ := range append(primitiveTypesUpper, "") {
		for _, opt := range []string{"", "OmitEmpty", "StringTag"} {
			opt := opt
			typ := typ

			op := fmt.Sprintf(
				"StructField%s%s",
				opt,
				typ,
			)
			opTypes = append(opTypes, opType{
				Op:                  op,
				Code:                "StructField",
				HeadToPtrHead:       func() string { return op },
				HeadToNPtrHead:      func() string { return op },
				HeadToAnonymousHead: func() string { return op },
				HeadToOmitEmptyHead: func() string { return op },
				HeadToStringTagHead: func() string { return op },
				HeadToOnlyHead:      func() string { return op },
				PtrHeadToHead:       func() string { return op },
				FieldToEnd: func() string {
					switch typ {
					case "", "Array", "Map", "MapLoad", "Slice", "Struct", "Recursive":
						return op
					}
					return fmt.Sprintf(
						"StructEnd%s%s",
						opt,
						typ,
					)
				},
				FieldToOmitEmptyField: func() string {
					return fmt.Sprintf(
						"StructFieldOmitEmpty%s",
						typ,
					)
				},
				FieldToStringTagField: func() string {
					return fmt.Sprintf(
						"StructFieldStringTag%s",
						typ,
					)
				},
			})
		}
	}
	for _, typ := range append(primitiveTypesUpper, "") {
		for _, opt := range []string{"", "OmitEmpty", "StringTag"} {
			opt := opt
			typ := typ

			op := fmt.Sprintf(
				"StructEnd%s%s",
				opt,
				typ,
			)
			opTypes = append(opTypes, opType{
				Op:                    op,
				Code:                  "StructEnd",
				HeadToPtrHead:         func() string { return op },
				HeadToNPtrHead:        func() string { return op },
				HeadToAnonymousHead:   func() string { return op },
				HeadToOmitEmptyHead:   func() string { return op },
				HeadToStringTagHead:   func() string { return op },
				HeadToOnlyHead:        func() string { return op },
				PtrHeadToHead:         func() string { return op },
				FieldToEnd:            func() string { return op },
				FieldToOmitEmptyField: func() string { return op },
				FieldToStringTagField: func() string { return op },
			})
		}
	}
	var b bytes.Buffer
	if err := tmpl.Execute(&b, struct {
		CodeTypes []string
		OpTypes   []opType
		OpLen     int
	}{
		CodeTypes: codeTypes,
		OpTypes:   opTypes,
		OpLen:     len(opTypes),
	}); err != nil {
		return err
	}
	path := filepath.Join(repoRoot(), "encode_optype.go")
	buf, err := format.Source(b.Bytes())
	if err != nil {
		return err
	}
	return ioutil.WriteFile(path, buf, 0644)
}

func repoRoot() string {
	_, file, _, _ := runtime.Caller(0)
	relativePathFromRepoRoot := filepath.Join("cmd", "generator")
	return strings.TrimSuffix(filepath.Dir(file), relativePathFromRepoRoot)
}

func main() {
	if err := _main(); err != nil {
		panic(err)
	}
}