// Copyright (C) MongoDB, Inc. 2017-present.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0

package bson

import "bytes"

// Marshal converts a BSON type to bytes.
//
// The value can be any one of the following types:
//
//   - bson.Marshaler
//   - io.Reader
//   - []byte
//   - bson.Reader
//   - any map with string keys
//   - a struct (possibly with tags)
//
// In the case of a struct, the lowercased field name is used as the key for each exported
// field but this behavior may be changed using a struct tag. The tag may also contain flags to
// adjust the marshalling behavior for the field. The tag formats accepted are:
//
//     "[<key>][,<flag1>[,<flag2>]]"
//
//     `(...) bson:"[<key>][,<flag1>[,<flag2>]]" (...)`
//
// The following flags are currently supported:
//
//     omitempty  Only include the field if it's not set to the zero value for the type or to
//                empty slices or maps.
//
//     minsize    Marshal an integer of a type larger than 32 bits value as an int32, if that's
// 				  feasible while preserving the numeric value.
//
//     inline     Inline the field, which must be a struct or a map, causing all of its fields
//                or keys to be processed as if they were part of the outer struct. For maps,
//                keys must not conflict with the bson keys of other struct fields.
//
// An example:
//
//     type T struct {
//         A bool
//         B int    "myb"
//         C string "myc,omitempty"
//         D string `bson:",omitempty" json:"jsonkey"`
//         E int64  ",minsize"
//         F int64  "myf,omitempty,minsize"
//     }
func Marshal(value interface{}) ([]byte, error) {
	var out bytes.Buffer

	err := NewEncoder(&out).Encode(value)
	if err != nil {
		return nil, err
	}

	return out.Bytes(), nil
}

// Unmarshal converts bytes into a BSON type.
//
// The value can be any one of the following types:
//
//   - bson.Unmarshaler
//   - io.Writer
//   - []byte
//   - bson.Reader
//   - any map with string keys
//   - a struct (possibly with tags)
//
// In the case of struct values, only exported fields will be deserialized. The lowercased field
// name is used as the key for each exported field, but this behavior may be changed using a struct
// tag. The tag may also contain flags to adjust the unmarshaling behavior for the field. The tag
// formats accepted are:
//
//     "[<key>][,<flag1>[,<flag2>]]"
//
//     `(...) bson:"[<key>][,<flag1>[,<flag2>]]" (...)`
//
// The target field or element types of out may not necessarily match the BSON values of the
// provided data. The following conversions are made automatically:
//
//   - Numeric types are converted if at least the integer part of the value would be preserved
//     correctly
//
// If the value would not fit the type and cannot be converted, it is silently skipped.
//
// Pointer values are initialized when necessary.
func Unmarshal(in []byte, out interface{}) error {
	return NewDecoder(bytes.NewReader(in)).Decode(out)
}

// UnmarshalDocument converts bytes into a *bson.Document.
func UnmarshalDocument(bson []byte) (*Document, error) {
	return ReadDocument(bson)
}