package structs

import (
	"errors"
	"fmt"

	"github.com/hashicorp/consul/api"
	multierror "github.com/hashicorp/go-multierror"
)

// TxnKVOp is used to define a single operation on the KVS inside a
// transaction
type TxnKVOp struct {
	Verb   api.KVOp
	DirEnt DirEntry
}

// TxnKVResult is used to define the result of a single operation on the KVS
// inside a transaction.
type TxnKVResult *DirEntry

// TxnKVOp is used to define a single operation on an Intention inside a
// transaction.
type TxnIntentionOp IntentionRequest

// TxnOp is used to define a single operation inside a transaction. Only one
// of the types should be filled out per entry.
type TxnOp struct {
	KV        *TxnKVOp
	Intention *TxnIntentionOp
}

// TxnOps is a list of operations within a transaction.
type TxnOps []*TxnOp

// TxnRequest is used to apply multiple operations to the state store in a
// single transaction
type TxnRequest struct {
	Datacenter string
	Ops        TxnOps
	WriteRequest
}

func (r *TxnRequest) RequestDatacenter() string {
	return r.Datacenter
}

// TxnReadRequest is used as a fast path for read-only transactions that don't
// modify the state store.
type TxnReadRequest struct {
	Datacenter string
	Ops        TxnOps
	QueryOptions
}

func (r *TxnReadRequest) RequestDatacenter() string {
	return r.Datacenter
}

// TxnError is used to return information about an error for a specific
// operation.
type TxnError struct {
	OpIndex int
	What    string
}

// Error returns the string representation of an atomic error.
func (e TxnError) Error() string {
	return fmt.Sprintf("op %d: %s", e.OpIndex, e.What)
}

// TxnErrors is a list of TxnError entries.
type TxnErrors []*TxnError

// TxnResult is used to define the result of a given operation inside a
// transaction. Only one of the types should be filled out per entry.
type TxnResult struct {
	KV TxnKVResult
}

// TxnResults is a list of TxnResult entries.
type TxnResults []*TxnResult

// TxnResponse is the structure returned by a TxnRequest.
type TxnResponse struct {
	Results TxnResults
	Errors  TxnErrors
}

// Error returns an aggregate of all errors in this TxnResponse.
func (r TxnResponse) Error() error {
	var errs error
	for _, err := range r.Errors {
		errs = multierror.Append(errs, errors.New(err.Error()))
	}
	return errs
}

// TxnReadResponse is the structure returned by a TxnReadRequest.
type TxnReadResponse struct {
	TxnResponse
	QueryMeta
}