// +build none

// This file generates runtimetypes.go from the AST of the TinyGo runtime
// package. This type information is necessary to avoid having to compile the
// runtime to compile any package.

package main

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/token"
	"io"
	"io/ioutil"
	"os"
	"strings"

	"golang.org/x/tools/go/packages"
)

// The list of runtime types known by the compiler.
var runtimeTypes = []string{
	// panic, recover
	"_defer",
	// strings
	"_string", "stringIterator",
	// map
	"hashmap", "hashmapBucket", "hashmapIterator",
	// channel
	"channel", "channelBlockedList", "chanSelectState",
	// interface
	"_interface", "interfaceMethodInfo", "typecodeID", "structField", "typeInInterface",
	// func
	"funcValue", "funcValueWithSignature",
}

// The list of runtime calls known to the compiler.
var runtimeCalls = []string{
	// panic, recover
	"_panic", "_recover",
	"nilPanic", "lookupPanic", "slicePanic", "chanMakePanic", "negativeShiftPanic",
	// string
	"stringEqual", "stringLess",
	"stringConcat",
	"stringFromBytes", "stringToBytes",
	"stringFromRunes", "stringToRunes",
	"stringFromUnicode",
	"stringNext",
	// complex
	"complex64div", "complex128div",
	// slice
	"sliceAppend", "sliceCopy",
	// memory
	"alloc", "trackPointer",
	// print builtin
	"printbool",
	"printint8", "printuint8",
	"printint16", "printuint16",
	"printint32", "printuint32",
	"printint64", "printuint64",
	"printfloat32", "printfloat64",
	"printcomplex64", "printcomplex128",
	"printstring", "printspace", "printnl",
	"printptr", "printmap", "printitf",
	// hashmap
	"hashmapMake", "hashmapLen", "hashmapNext",
	"hashmapStringGet", "hashmapStringSet", "hashmapStringDelete",
	"hashmapInterfaceGet", "hashmapInterfaceSet", "hashmapInterfaceDelete",
	"hashmapBinaryGet", "hashmapBinarySet", "hashmapBinaryDelete",
	// channel, concurrency
	"tryChanSelect", "chanMake", "chanSend", "chanRecv", "chanClose", "chanSelect",
	"deadlock",
	// interface, reflect
	"interfaceEqual", "interfaceImplements", "interfaceMethod",
	"typeAssert", "interfaceTypeAssert",
	// func
	"getFuncPtr",
}

// makeDefs generates runtimetypes.go and writes it out after formatting it.
func makeDefs() error {
	// Load the runtime package.
	pkgs, err := packages.Load(&packages.Config{
		Mode:       packages.NeedSyntax,
		BuildFlags: []string{"-tags=gc.extalloc"},
	}, "../src/runtime")
	if err != nil {
		return err
	}
	if len(pkgs) != 1 {
		return fmt.Errorf("expected 1 package, got %d", len(pkgs))
	}
	runtimePkg := pkgs[0]
	if len(runtimePkg.Errors) != 0 {
		return runtimePkg.Errors[0]
	}

	// Start creating the new Go file.
	buf := &bytes.Buffer{}
	buf.WriteString(`// Autogenerated by mkruntimetypes.go, DO NOT EDIT.

package compiler

// This file contains definitions for runtime types and functions, so that the
// runtime package can be compiled independently of other packages.

import (
	"go/token"
	"go/types"
	"strconv"
)

// getRuntimeType constructs a new runtime type with the given name. The types
// constructed here must match the types in the runtime package.
func (c *compilerContext) getRuntimeType(name string) types.Type {
	if c.program != nil {
		return c.program.ImportedPackage("runtime").Type(name).Type()
	}
	if typ, ok := c.runtimeTypes[name]; ok {
		// This type was already created.
		return typ
	}

	typeName := types.NewTypeName(token.NoPos, c.runtimePkg, name, nil)
	named := types.NewNamed(typeName, nil, nil)

	// Make sure recursive types are only defined once.
	c.runtimeTypes[name] = named

	var fieldTypes []types.Type
	switch name {
`)
	err = makeTypeDefs(buf, runtimePkg)
	if err != nil {
		return err
	}
	buf.WriteString(`		default:
		panic("could not find runtime type: runtime." + name)
	}

	// Create the named struct type.
	var fields []*types.Var
	for i, t := range fieldTypes {
		// Field name doesn't matter: this type is only used to create a LLVM
		// struct type which don't have field names.
		fields = append(fields, types.NewField(token.NoPos, nil, "field"+strconv.Itoa(i), t, false))
	}
	named.SetUnderlying(types.NewStruct(fields, nil))
	return named
}

// getRuntimeFuncType constructs a new runtime function signature with the given
// name. The function signatures constructed here must match the functions in
// the runtime package.
func (c *compilerContext) getRuntimeFuncType(name string) *types.Signature {
	var params []*types.Var
	addParam := func(name string, typ types.Type) {
		params = append(params, types.NewParam(token.NoPos, c.runtimePkg, name, typ))
	}
	var results []*types.Var
	addResult := func(typ types.Type) {
		results = append(results, types.NewParam(token.NoPos, c.runtimePkg, "", typ))
	}
	switch name {
`)

	err = makeFuncDefs(buf, runtimePkg)
	if err != nil {
		return err
	}
	buf.WriteString(`	default:
		panic("unknown runtime call: runtime." + name)
	}
	return types.NewSignature(nil, types.NewTuple(params...), types.NewTuple(results...), false)
}
`)

	source, err := format.Source(buf.Bytes())
	if err != nil {
		// Fallback (useful for investigating errors).
		source = buf.Bytes()
	}
	err2 := ioutil.WriteFile("runtimetypes.go", source, 0666)
	if err2 != nil {
		return err2 // error from ioutil.WriteFile
	}
	return err // error from format.Source (if any)
}

// makeTypeDefs generates the switch body of the getRuntimeType function.
func makeTypeDefs(w io.Writer, runtimePkg *packages.Package) error {
	typeSpecs := map[string]*ast.TypeSpec{}
	for _, file := range runtimePkg.Syntax {
		for _, decl := range file.Decls {
			switch decl := decl.(type) {
			case *ast.GenDecl:
				if decl.Tok != token.TYPE {
					continue
				}
				for _, spec := range decl.Specs {
					typeSpec := spec.(*ast.TypeSpec)
					typeSpecs[typeSpec.Name.Name] = typeSpec
				}
			}
		}
	}

	for _, name := range runtimeTypes {
		typeSpec := typeSpecs[name]
		if typeSpec == nil {
			return fmt.Errorf("could not find type: %s", name)
		}
		fmt.Fprintf(w, "\tcase %#v:\n", typeSpec.Name.Name)
		if name == "channelBlockedList" {
			fmt.Fprintf(w, "\t\ttaskType := types.NewNamed(types.NewTypeName(token.NoPos, c.taskPkg, \"Task\", nil), nil, nil)\n")
		}
		fmt.Fprintf(w, "\t\tfieldTypes = []types.Type{\n")
		for _, field := range typeSpec.Type.(*ast.StructType).Fields.List {
			fieldType := getTypeFromExpr(field.Type, typeSpec.Name.Name)
			for _, ident := range field.Names {
				fmt.Fprintf(w, "\t\t\t%s, // %s\n", fieldType, ident.Name)
			}
		}
		fmt.Fprintf(w, "\t\t}\n")
	}
	return nil
}

// makeFuncDefs generates the switch body of the getRuntimeFuncType function.
func makeFuncDefs(w io.Writer, runtimePkg *packages.Package) error {
	functions := map[string]*ast.FuncDecl{}
	for _, file := range runtimePkg.Syntax {
		for _, decl := range file.Decls {
			switch decl := decl.(type) {
			case *ast.FuncDecl:
				functions[decl.Name.Name] = decl
			default:
			}
		}
	}

	for _, name := range runtimeCalls {
		decl := functions[name]
		if decl == nil {
			return fmt.Errorf("could not find function: %s", name)
		}
		fmt.Fprintf(w, "\tcase %#v:\n", decl.Name.Name)
		for _, field := range decl.Type.Params.List {
			typeString := getTypeFromExpr(field.Type, "")
			for _, name := range field.Names {
				fmt.Fprintf(w, "\t\taddParam(%#v, %s)\n", name.Name, typeString)
			}
		}
		if decl.Type.Results != nil {
			for _, field := range decl.Type.Results.List {
				typeString := getTypeFromExpr(field.Type, "")
				for range field.Names {
					fmt.Fprintf(w, "\t\taddResult(%s)\n", typeString)
				}
				if len(field.Names) == 0 {
					fmt.Fprintf(w, "\t\taddResult(%s)\n", typeString)
				}
			}
		}
	}
	return nil
}

// getTypeFromExpr returns a string which is a piece of Go code that constructs
// the type (as given in ast.Expr) using the go/types package.
func getTypeFromExpr(typ ast.Expr, currentTypeName string) string {
	switch typ := typ.(type) {
	case *ast.Ident:
		if typ.Name == currentTypeName {
			// Assume a global named "named" which refers to the currently
			// created named type.
			return "named"
		}
		switch typ.Name {
		case "bool", "int", "int8", "int16", "int32", "int64", "uint", "uint8", "uint16", "uint32", "uint64", "uintptr", "float32", "float64", "complex64", "complex128", "string", "byte", "rune":
			// Built-in types.
			return fmt.Sprintf("types.Typ[types.%s]", strings.Title(typ.Name))
		case "chanState":
			// runtime.chanState is a named type, but that doesn't matter when
			// generating LLVM IR.
			return fmt.Sprintf("types.Typ[types.Uint8]")
		default:
			// Assume that we can simply get the type recursively.
			return fmt.Sprintf("c.getRuntimeType(%#v)", typ.Name)
		}
	case *ast.StarExpr:
		return fmt.Sprintf("types.NewPointer(%s)", getTypeFromExpr(typ.X, currentTypeName))
	case *ast.InterfaceType:
		if len(typ.Methods.List) != 0 {
			// Unimplemented: interfaces with methods.
			return "interface{?}"
		}
		return "types.NewInterfaceType(nil, nil)"
	case *ast.ArrayType:
		// Slices and arrays. Assume the array length is a numeric constant and
		// not a Go named constant for example.
		elementType := getTypeFromExpr(typ.Elt, currentTypeName)
		if typ.Len == nil {
			return fmt.Sprintf("types.NewSlice(%s)", elementType)
		}
		length := typ.Len.(*ast.BasicLit).Value
		return fmt.Sprintf("types.NewArray(%s, %s)", elementType, length)
	case *ast.SelectorExpr:
		s := typ.X.(*ast.Ident).Name + "." + typ.Sel.Name
		switch s {
		case "unsafe.Pointer":
			return "types.Typ[types.UnsafePointer]"
		case "task.Task":
			// Assume there is a variable taskType which refers to the task.Task
			// structure.
			return "taskType"
		default:
			return fmt.Sprintf("<unknown %s>", s)
		}
	case *ast.StructType:
		// Inline struct type.
		var fields string
		for _, field := range typ.Fields.List {
			fieldType := getTypeFromExpr(field.Type, currentTypeName)
			for _, ident := range field.Names {
				fields += fmt.Sprintf("\t\t\ttypes.NewField(token.NoPos, nil, %#v, %s, false),\n", ident.Name, fieldType)
			}
		}
		return fmt.Sprintf("types.NewStruct([]*types.Var{\n%s\t\t}, nil)", fields)
	default:
		// Dump the raw typ value, for debugging.
		return fmt.Sprintf("%#v", typ)
	}
}

func main() {
	err := makeDefs()
	if err != nil {
		fmt.Fprintln(os.Stderr, "could not create defs:", err)
		os.Exit(1)
	}
}