//go:build tools

package main

import (
	"fmt"
	"go/ast"
	"log"
	"os"
	"path/filepath"
	"text/template"

	phpast "github.com/laytan/php-parser/pkg/ast"
	"golang.org/x/tools/go/packages"
)

type nodeType struct {
	// The type name.
	Name string
	// The function name.
	FuncName string
	// Map of field names to whether the field is an array or not.
	Traversable map[string]bool
}

type templData struct {
	Types []nodeType
}

var fileTempl = template.Must(
	template.New("").Parse(`// Code generated by "go generate go run traverser_gen.go"; DO NOT EDIT.

package traverser

import "github.com/laytan/php-parser/pkg/ast"
{{range $typ := .Types}}
func (t *Traverser) {{$typ.FuncName}}(n *ast.{{$typ.Name}}) {
    if !t.checkEntrance(n) {
        return
    }

    n.Accept(t.v)
{{range $name, $isArray := $typ.Traversable}}
{{- if $isArray}}
    for _, nn := range n.{{$name}} {
        nn.Accept(t)
    }
{{else}}
    t.Traverse(n.{{$name}})
{{end}}
{{- end}}
    t.leave(n)
}
{{end}}`),
)

func main() {
	ast := astOfFile("../../ast/node.go")
	nodeTypes := getNodeTypes(ast)

	file, err := os.Create("traverser_impl.go")
	if err != nil {
		panic(fmt.Errorf("open 'traverser_impl.go': %w", err))
	}

	fileTempl.Execute(file, templData{Types: nodeTypes})
}

func astOfFile(path string) *ast.File {
	nodesFile, err := filepath.Abs(path)
	if err != nil {
		panic(fmt.Errorf("getting '%s' absolute path: %w", path, err))
	}

	cfg := &packages.Config{
		Mode:  packages.NeedName | packages.NeedFiles | packages.NeedTypes | packages.NeedTypesInfo | packages.NeedSyntax,
		Tests: false,
	}
	pkgs, err := packages.Load(cfg, fmt.Sprintf("file=%s", nodesFile))
	if err != nil {
		panic(fmt.Errorf("loading '%s' package: %w", nodesFile, err))
	}

	if len(pkgs) == 0 {
		panic(fmt.Errorf("could not get any package for file '%s'", nodesFile))
	}

	pkg := pkgs[0]
	var syntax *ast.File
	for i, fn := range pkg.GoFiles {
		if fn == nodesFile {
			syntax = pkg.Syntax[i]
			break
		}
	}

	if syntax == nil {
		panic(fmt.Errorf("could not get ast of file: '%s'", nodesFile))
	}

	return syntax
}

func getNodeTypes(syntax *ast.File) []nodeType {
	types := []nodeType{}
	for _, decl := range syntax.Decls {
		typedDecl, ok := decl.(*ast.GenDecl)
		if !ok {
			log.Printf("%T not *ast.GenDecl", decl)
			continue
		}

		for _, spec := range typedDecl.Specs {
			typedSpec, ok := spec.(*ast.TypeSpec)
			if !ok {
				if _, ok := spec.(*ast.ImportSpec); !ok {
					log.Printf("%T not *ast.TypeSpec", spec)
				}
				continue
			}

			structType, ok := typedSpec.Type.(*ast.StructType)
			if !ok {
				log.Printf("%T not *ast.StructType", spec)
				continue
			}

			nType := nodeType{
				Name:        typedSpec.Name.String(),
				FuncName:    typedSpec.Name.String(),
				Traversable: map[string]bool{},
			}
			if funcName, ok := phpast.TypeToVisitorNameMap[typedSpec.Name.String()]; ok {
				nType.FuncName = funcName
			}

			for _, field := range structType.Fields.List {
				if traversable, isArray := checkType(field.Type); traversable {
					for _, n := range field.Names {
						nType.Traversable[n.String()] = isArray
					}
				}
			}

			types = append(types, nType)
		}
	}

	return types
}

func checkType(t ast.Expr) (traversable bool, isArray bool) {
	switch ft := t.(type) {
	case *ast.ArrayType:
		ok, _ := checkType(ft.Elt)
		return ok, true
	case *ast.Ident:
		switch ft.Name {
		case "Vertex":
			return true, false
		default:
			return false, false
		}
	default:
		return false, false
	}
}