package df

import (
	"bytes"
	"encoding/json"
	"fmt"
	"go/format"
	"io/ioutil"
	"os"
	"text/template"

	"github.com/iancoleman/strcase"
)

var backendTemplate = template.Must(template.New("").Parse(`// Code generated by legendsbrowser; DO NOT EDIT.
package model

import (
	"encoding/xml"
	"strconv"
	"fmt"
)

{{- range $name, $obj := $.Objects }}
type {{ $obj.Name }} struct {
	{{- range $fname, $field := $obj.Fields }}
	{{- if not (and (eq $fname "type") (not (not $obj.SubTypes))) }}
	{{ $field.TypeLine }}
	{{- end }}
	{{- end }}
	{{- if not (not $obj.SubTypes) }}
	Details any
	{{- end }}
}

{{- if $obj.Id }}
func (x *{{ $obj.Name }}) Id() int { return x.Id_ }
{{- end }}
{{- if $obj.Named }}
func (x *{{ $obj.Name }}) Name() string { return x.Name_ }
{{- end }}
{{- end }}

// Parser

func n(d []byte) int {
	v, _ := strconv.Atoi(string(d))
	return v
}

{{- range $name, $obj := $.Objects }}
{{- range $plus := $.Modes }}
func parse{{ $obj.Name }}{{ if $plus }}Plus{{ end }}(d *xml.Decoder, start *xml.StartElement{{ if $plus }}, obj *{{ $obj.Name }}{{ end }}) (*{{ $obj.Name }}, error) {
	var (
		{{- if not $plus }}
		obj = &{{ $obj.Name }}{}
		{{- end }}
		data []byte
	)
	{{- if $plus }}
	if obj == nil {
		obj = &{{ $obj.Name }}{}
	}
	{{- end }}

	{{- range $fname, $field := $obj.Fields }}
		{{ $field.Init $plus }}
	{{- end }}

	for {
		tok, err := d.Token()
		if err != nil {
			return nil, err
		}
		switch t := tok.(type) {
		case xml.StartElement:
			switch t.Name.Local {
			{{- range $fname, $field := $obj.Fields }}
			{{- if $field.Active $plus }}
			case "{{ $fname }}":
				{{ $field.StartAction $plus }}
			{{- end }}
			{{- end }}
			default:
				// fmt.Println("unknown field", t.Name.Local)
				d.Skip()
			}

		case xml.CharData:
			data = append(data, t...)

		case xml.EndElement:
			if t.Name.Local == start.Name.Local {
				return obj, nil
			}

			switch t.Name.Local {
			{{- range $fname, $field := $obj.Fields }}{{- if $field.Active $plus }}
			case "{{ $fname }}":
				{{- if and (eq $fname "type") (not (not $obj.SubTypes)) }}
		
				var err error
				switch string(data) {
				{{- range $sub := ($obj.ActiveSubTypes $plus) }}
				case "{{ $sub.Case }}":
					{{- if eq 1 (len $sub.Options) }}
					{{- if not $plus }}
					obj.Details, err = parse{{ $sub.Name }}(d, start)
					{{- else }}
					obj.Details, err = parse{{ $sub.Name }}Plus(d, start, obj.Details.(*{{ $sub.Name }}))
					{{- end }}
					{{- else }}
					switch details := obj.Details.(type) {
						{{- range $opt := $sub.Options }}
					case *{{ $opt}}:
						obj.Details, err = parse{{ $opt }}Plus(d, start, details)
						{{- end }}
					default:
						fmt.Println("unknown subtype option", obj.Details)
						d.Skip()
					}
					{{- end }}
				{{- end }}
				default:
					d.Skip()
				}
				if err != nil {
					return nil, err
				}
				return obj, nil
				
				{{- else }}
				{{ $field.EndAction }}
				{{- end }}
			{{- end }}{{- end }}
			default:
				// fmt.Println("unknown field", t.Name.Local)
			}
		}
	}
}
{{- end }}
{{- end }}
`))

func generateBackendCode(objects *Metadata) error {
	file, _ := json.MarshalIndent(objects, "", "  ")
	_ = ioutil.WriteFile("model.json", file, 0644)

	f, err := os.Create("../backend/model/model.go")
	if err != nil {
		return err
	}
	defer f.Close()

	var buf bytes.Buffer
	err = backendTemplate.Execute(&buf, struct {
		Objects *Metadata
		Modes   []bool
	}{
		Objects: objects,
		Modes:   []bool{false, true},
	})
	if err != nil {
		return err
	}
	p, err := format.Source(buf.Bytes())
	if err != nil {
		fmt.Println("WARN: could not format source", err)
		p = buf.Bytes()
	}
	_, err = f.Write(p)
	return err
}

func (f Field) TypeLine() string {
	n := f.Name

	if n == "Id" || n == "Name" {
		n = n + "_"
	}

	m := ""
	if f.Multiple {
		m = "[]"
	}
	t := f.Type
	if f.Type == "array" {
		t = "[]*" + *f.ElementType
	}
	if f.Type == "map" {
		t = "map[int]*" + *f.ElementType
	}
	if f.Type == "object" {
		t = "*" + *f.ElementType
	}
	j := fmt.Sprintf("`json:\"%s\" legend:\"%s\"`", strcase.ToLowerCamel(f.Name), f.Legend)
	return fmt.Sprintf("%s %s%s %s", n, m, t, j)
}

func (f Field) Init(plus bool) string {
	if !plus && f.Type == "map" {
		return fmt.Sprintf("obj.%s = make(map[int]*%s)", f.Name, *f.ElementType)
	}

	return ""
}

func (f Field) StartAction(plus bool) string {
	n := f.Name

	if n == "Id" || n == "Name" {
		n = n + "_"
	}

	if f.Type == "object" {
		p := fmt.Sprintf("v, _ := parse%s(d, &t)", *f.ElementType)
		if !f.Multiple {
			return fmt.Sprintf("%s\nobj.%s = v", p, n)
		} else {
			return fmt.Sprintf("%s\nobj.%s = append(obj.%s, v)", p, n, n)
		}
	}

	if f.Type == "array" || f.Type == "map" {
		gen := fmt.Sprintf("parse%s", *f.ElementType)

		if f.Type == "array" {
			return fmt.Sprintf("parseArray(d, &obj.%s, %s)", f.Name, gen)
		}

		if f.Type == "map" {
			if !plus {
				return fmt.Sprintf("parseMap(d, &obj.%s, %s)", f.Name, gen)
			} else {
				gen = fmt.Sprintf("parse%sPlus", *f.ElementType)
				return fmt.Sprintf("parseMapPlus(d, &obj.%s, %s)", f.Name, gen)
			}
		}
	}

	if f.Type == "int" || f.Type == "string" || f.Type == "bool" {
		return "data = nil"
	}

	return ""
}

func (f Field) EndAction() string {
	n := f.Name

	if n == "Id" || n == "Name" {
		n = n + "_"
	}

	if !f.Multiple {
		if f.Type == "int" {
			return fmt.Sprintf("obj.%s = n(data)", n)
		} else if f.Type == "string" {
			return fmt.Sprintf("obj.%s = string(data)", n)
		} else if f.Type == "bool" {
			return fmt.Sprintf("obj.%s = true", n)
		}
	} else {
		if f.Type == "int" {
			return fmt.Sprintf("obj.%s = append(obj.%s, n(data))", n, n)
		} else if f.Type == "string" {
			return fmt.Sprintf("obj.%s = append(obj.%s, string(data))", n, n)
		}
	}

	return ""
}