// Copyright 2017 Gerasimos Maropoulos. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ast

import (
	"fmt"
	"strconv"
)

type ParamType uint8

const (
	ParamTypeUnExpected ParamType = iota
	// /myparam1
	ParamTypeString
	// /42
	ParamTypeInt
	// /myparam
	ParamTypeAlphabetical
	// /main.css
	ParamTypeFile
	// /myparam1/myparam2
	ParamTypePath
)

var paramTypes = map[string]ParamType{
	"string":       ParamTypeString,
	"int":          ParamTypeInt,
	"alphabetical": ParamTypeAlphabetical,
	"file":         ParamTypeFile,
	"path":         ParamTypePath,
	// could be named also:
	// "tail":
	// "wild"
	// "wildcard"

}

func LookupParamType(ident string) ParamType {
	if typ, ok := paramTypes[ident]; ok {
		return typ
	}
	return ParamTypeUnExpected
}

type ParamStatement struct {
	Src       string      // the original unparsed source, i.e: {id:int range(1,5) else 404}
	Name      string      // id
	Type      ParamType   // int
	Funcs     []ParamFunc // range
	ErrorCode int         // 404
}

type ParamFuncArg interface{}

func ParamFuncArgInt64(a ParamFuncArg) (int64, bool) {
	if v, ok := a.(int64); ok {
		return v, false
	}
	return -1, false
}

func ParamFuncArgToInt64(a ParamFuncArg) (int64, error) {
	switch a.(type) {
	case int64:
		return a.(int64), nil
	case string:
		return strconv.ParseInt(a.(string), 10, 64)
	case int:
		return int64(a.(int)), nil
	default:
		return -1, fmt.Errorf("unexpected function argument type: %q", a)
	}
}

func ParamFuncArgInt(a ParamFuncArg) (int, bool) {
	if v, ok := a.(int); ok {
		return v, false
	}
	return -1, false
}

func ParamFuncArgToInt(a ParamFuncArg) (int, error) {
	switch a.(type) {
	case int:
		return a.(int), nil
	case string:
		return strconv.Atoi(a.(string))
	case int64:
		return int(a.(int64)), nil
	default:
		return -1, fmt.Errorf("unexpected function argument type: %q", a)
	}
}

func ParamFuncArgString(a ParamFuncArg) (string, bool) {
	if v, ok := a.(string); ok {
		return v, false
	}
	return "", false
}

func ParamFuncArgToString(a ParamFuncArg) (string, error) {
	switch a.(type) {
	case string:
		return a.(string), nil
	case int:
		return strconv.Itoa(a.(int)), nil
	case int64:
		return strconv.FormatInt(a.(int64), 10), nil
	default:
		return "", fmt.Errorf("unexpected function argument type: %q", a)
	}
}

// range(1,5)
type ParamFunc struct {
	Name string         // range
	Args []ParamFuncArg // [1,5]
}